Technical field
[0001]
　The present invention, metal moldings and a method of manufacturing comprising a tubular portion having a slit, and a manufacturing apparatus and molds used therein.
Background technique
[0002]
　Tubular parts to automobile parts and household electrical products have been widely used. Therefore, development of a technology for producing a tubular component is promoted. Typical methods for producing tubular components a metal plate as material, UO molding is known (e.g. Patent Documents 1 and 2).
[0003]
　In recent years, in the automotive field, there is a need for a tubular part having a slit in the longitudinal direction. As a method for producing such a tubular part, a method of performing a plurality of times bending have been conventionally used. However, in the method, a problem that the molding of complex shaped parts is difficult, and there is a problem that the process is complicated. Therefore, applications of UO molding is expected. However, typical UO molding is a method for manufacturing a slit is not tubular part, the butted portion of the tubular part molded is welded. Therefore, only applying conventional UO molding, it is difficult to accurately produce a tubular part having a gap in the abutting portion.
[0004]
　Patent Document 3 discloses a method of forming a hollow profile in the longitudinal direction with a slot. FIG. 3 and FIG. 4 of Patent Document 3, a method of using a core (core 11) comprising a blade for forming a slot is disclosed. Manufacturing method of Patent Document 3, it is assumed that welding close the slot after molding. Therefore, the accuracy of the precision and welding shape before the interval of the slot is not considered. Further, if the material and thickness of the metal plate has changed to change the spring back amount, variations occur in the interval of the slot. Therefore, when changing the material and thickness of the metal plate, the mold of the correction is required in order to adjust the spacing of the slot.
[0005]
　In Patent Document 1, by bending a plate material, a method of cross-section forming a tubular member of rectangular is disclosed. Mold used in this method, the upper mold, the lower mold, and a side die. Side die is a die for pressing the sides of the plate so as to close the two edges facing each other. Tubular member formed in this way, part butt after molding is welded. Therefore, it not sufficiently considered for the control of the spacing between the two edges.　　　
[0006]
　Further, as the method for producing tubular components, it is also known roll forming (for example, Patent Document 4). However, the roll forming, the production of tubular parts having a complicated shape of irregular cross section tubes or the like in the longitudinal cross-sectional shape changes is difficult.
[0007]
　As bending of the metal plate, press brake processing is known (e.g. Patent Document 5). The bending by the press brake, it is also conceivable to mold the tubular part having a gap in the abutting portion. However, in the press brake processing, it is difficult to reduce the width of the gap of the butted portion.
[0008]
　Even in conventional UO forming, by a spring-back after forming, the abutting portions of the tubular part, there is a case where unintended gap is. However, in the conventional UO molding, it is very difficult to control the width of the gap of the butted portion.
[0009]
　Further, for example, as described in Patent Documents 2 and 3 may use a core at O ​​molding. In this case, by shortening than the cross-section perimeter of the mold the width of the metal plate, it is conceivable to shape the tubular part having a gap in the abutting portion. However, since the molding by simply bending in this way, there is a problem that the spring-back is large. Therefore, control of the gap distance also butted portion in this case is difficult.
[0010]
　Also, make the mold design by trial and error, using the mold, it is conceivable to a tubular part having a gap for molding by utilizing the spring-back to the butt portion. However, when considering mass production, material and thickness of the metal plate is slightly changed depending on the lot change. In that case, in order to change the spring back amount, variation in the shape of the interval and the tubular part of the gap of the butted portion. Therefore, at intervals of the gap of the butted portion is constant, it is difficult to continue mass production of good tubular part geometry accuracy. Furthermore, when changing the material and thickness of the metal plate, it is necessary to mold modified to adjust the width of the gap of the butted portion, it requires much time and labor, resulting in high cost the lead.
[0011]
　Patent Document 6, using UO molding technique, discloses a process for producing a hollow atypical material from the cut blanks. In the manufacturing method of Patent Document 6, forming a hollow atypical material closed by contact with each other the two opposite edges of the cut blanks. At this time, the circumferential length of the cut blanks, than the required molding length, longer by a predetermined excess length. The excess length is at least 1% to 10%. Patent Document 6, the area of ​​the hollow atypical material abuts the edge joint is disclosed to be compressed at least partially circumferentially. Further, Patent Document 6, it is described that to implement the above manufacturing method using UO molding techniques. However, Patent Document 6, how to implement the manufacturing method is not described in detail. That is, using the UO molding techniques, how to compress the hollow atypical material in the circumferential direction, it is not disclosed in patent document 6. Furthermore, the method of Patent Document 6 is not assumed to be arbitrarily control the width of the slit.
CITATION
Patent Literature
[0012]
Patent Document 1: JP 2001-191112 Patent Publication
Patent Document 2: JP 2004-25224 JP
Patent Document 3: WO 2005/002753 pamphlet
Patent Document 4: JP 2000-616 JP
Patent Document 5: JP open 2000-61551 JP
Patent Document 6: JP-T 2014-516801 Patent Publication
Summary of the Invention
Problems that the Invention is to Solve
[0013]
　In the above circumstances, one object of the present invention, by forming accurately metal molded article comprising a tubular portion having a slit is to provide a manufacturing method capable of controlling the spacing of the slits.
Means for Solving the Problems
[0014]
　The method of an embodiment of the present invention is a method of manufacturing the metal formed article comprising a tubular portion having a slit. This manufacturing method by deforming the (i) a metal plate, a step of cross-section to form a U-shaped portion is U-shaped, a (ii) 2 two ends of the U-shaped portion projecting portions by deforming the U-shaped portion with a mold having the protruding portion so as to sandwich, and forming said tubular portion having said slit. In the step of the (ii), is shorter than the sectional length LU of the cross-sectional circumferential length LH of the tubular portion and the U-shaped portion.
[0015]
　Metal formed article of an embodiment of the present invention is a metal molded article comprising a tubular portion having a slit. When representing the variation S of the plate thickness direction of the Vickers hardness in the cross section of the tubular portion by the following equation, the average value of the circumferential variation S is less than 0.4.
　S = (Bmax-Bmin) / Bmax
, where, Bmin is the minimum value of the thickness direction of the Vickers hardness in the cross-section. Bmax is the maximum value of the thickness direction of the Vickers hardness in the cross-section.
[0016]
　Manufacturing apparatus of one embodiment of the present invention is a manufacturing apparatus for manufacturing a metal molded article comprising a tubular portion having a slit. The manufacturing apparatus includes a die, a moving mechanism for moving the mold. The mold comprises a first mold including a protrusion for forming the slits, and a second mold. Each of the first and second mold, the first and second pressing surfaces for forming the cylindrical portion having a gap section is the slit to deform the U-shaped portion is U-shaped including. The mold has a configuration for pressing the cylindrical outer peripheral surface of such cross-sectional circumference of the tubular portion is shortened.
[0017]
　Mold of an embodiment of the present invention is a mold for manufacturing a metal molded article comprising a tubular portion having a slit. The mold comprises a first mold including a protrusion for forming the slits, and a second mold. Each of the first and second mold, the first and second pressing surfaces for forming the cylindrical portion having a gap section is the slit to deform the U-shaped portion is U-shaped including. The mold has a configuration for pressing the cylindrical outer peripheral surface of such cross-sectional circumference of the tubular portion is shortened.
Effect of the invention
[0018]
　According to the present invention, the metal formed article with high accuracy mold comprising a tubular portion having a slit, it is possible to control the spacing of the slits. According to the present invention, a metal molded article comprising a tubular portion in which slits are precisely formed is obtained. Furthermore, according to the present invention, preferably the manufacturing apparatus and molds used in the production process of the present invention is obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019]
[1] Figure 1 is an example of a cross section of a metal formed article of the present invention is shown schematically.
[Figure 2A] Figure 2A is a cross-sectional view schematically showing an example of one step of the manufacturing method of the present invention.
[Figure 2B] Figure 2B is a sectional view showing an example of a process subsequent to that in FIG. 2A schematically.
[Figure 2C] FIG 2C is a cross-sectional view schematically showing the U-shaped portion formed in the step of FIG. 2A and 2B.
[Figure 3A] Figure 3A is a cross-sectional view schematically showing an example of a mold used in the manufacturing method of the present invention.
[Figure 3B] Figure 3B is a cross-sectional view showing an example of a manufacturing process using a mold of FIG. 3A schematically.
FIG 3C] Figure 3C is a cross-sectional view showing an example of a process subsequent to the step of FIG. 3B.
[Figure 3D] Figure 3D is a cross-sectional view showing an example of a process subsequent to the step of FIG. 3C.
FIG 3E] Figure 3E is a sectional view showing an example of a process subsequent to FIG. 3D process.
FIG 3F] Figure 3F is a cross-sectional view schematically showing an example of a metal formed article manufactured in FIGS. 3B ~ Figure 3E steps.
[Figure 4A] Figure 4A is a cross-sectional view schematically showing an example of a mold used in the manufacturing method of the present invention.
[Figure 4B] Figure 4B is a cross-sectional view showing an example of a manufacturing process using a mold of Figure 4A schematically.
[Figure 4C] Figure 4C is a sectional view showing an example of a process subsequent to the step of FIG. 4B.
[FIG. 4D] FIG. 4D is a cross-sectional view showing an example of a process subsequent to the step of FIG. 4C.
[FIG. 4E] FIG. 4E is a cross-sectional view showing an example of a process subsequent to the step of FIG. 4D.
[FIG. 4F] FIG. 4F is a cross-sectional view schematically showing an example of a metal formed article produced by the process of FIG. 4B ~ Figure 4E.
[Figure 5A] Figure 5A is a cross-sectional view schematically showing an example of a mold used in the manufacturing method of the present invention.
[Figure 5B] Figure 5B is a cross-sectional view showing an example of a manufacturing process using a mold of Figure 5A schematically.
[Figure 5C] Figure 5C is a cross-sectional view showing an example of a process subsequent to the process of Figure 5B.
[Figure 5D] Figure 5D is a cross-sectional view showing an example of a process subsequent to the step of FIG. 5C.
FIG 5E] Figure 5E is a cross-sectional view showing an example of a process subsequent to the step of FIG. 5D.
FIG 5F] Figure 5F is a cross-sectional view schematically showing an example of a metal formed article produced by the process of FIG. 5B ~ Figure 5E.
[Figure 6A] Figure 6A is a cross-sectional view schematically showing an example of a mold used in the manufacturing method of the present invention.
[Figure 6B] Figure 6B is a cross-sectional view showing an example of a manufacturing process using a mold of Figure 6A schematically.
[Figure 6C] Figure 6C is a cross-sectional view showing an example of a process subsequent to the step of Figure 6B.
FIG 6D] FIG. 6D is a cross-sectional view showing an example of a process subsequent to the step of FIG. 6C.
FIG 6E] FIG 6E is a sectional view showing an example of a process subsequent to the step of FIG. 6D.
FIG 6F] FIG. 6F is a cross-sectional view schematically showing an example of a metal formed article produced by the process of FIG. 6B ~ Figure 6E.
[7] FIG. 7 is a sectional view showing in section schematically another example of a mold of the present invention.
[8] FIG. 8 is a sectional view showing an example of an example, and a tubular portion which is formed by it the other mold of the present invention.
FIG 9A] FIG 9A is a diagram schematically showing an example of a metal formed article of the present invention.
[FIG. 9B] FIG 9B is another example of a metal formed article of the present invention is a diagram schematically showing.
FIG 9C] FIG 9C are other diagrams schematically illustrating an example of a metal molded article of the present invention.
FIG 9D] FIG 9D are other diagrams schematically illustrating an example of a metal molded article of the present invention.
FIG 9E] FIG 9E are other diagrams schematically illustrating an example of a metal molded article of the present invention.
FIG 10A] FIG 10A shows one step of the manufacturing method of the tubular member of Comparative Example 1 is schematically shown.
[FIG. 10B] FIG 10B shows a process subsequent to FIG. 10A schematically.
FIG 11A] FIG 11A shows one step of the manufacturing method of the tubular member of Comparative Example 2 schematically.
FIG 11B] FIG 11B shows a process subsequent to FIG. 11A schematically.
FIG 12A] FIG 12A is a first embodiment, the tubular member of Comparative Example 1 and Comparative Example 2 is a graph showing the strain distribution in the thickness direction.
[Figure 12B] Figure 12B is the tubular member of Examples 2-4 and Comparative Example 2 is a graph showing the strain distribution in the circumferential direction.
[13] FIG 13 is a graph showing the relationship between the circumferential average value and the reduction rate of the uniaxial compressive strength of variation S.
[Figure 14A] Figure 14A is one example of a manufacturing apparatus of the present invention, is a diagram showing an example of operation.
FIG 14B] FIG 14B is a diagram showing an example of the operation subsequent to FIG. 14A.
FIG 14C] FIG 14C is a diagram showing an example of the operation subsequent to FIG. 14B.
[FIG. 14D] FIG 14D is a diagram showing an example of the operation subsequent to FIG. 14C.
[Figure 15A] Figure 15A, another example of manufacturing apparatus of the present invention, is a diagram showing an example of operation.
[FIG. 15B] FIG 15B is a diagram showing an example of the operation subsequent to FIG. 15A.
[FIG. 15C] FIG 15C is a diagram showing an example of the operation subsequent to FIG. 15B.
FIG 15D] FIG 15D is a diagram showing an example of the operation subsequent to FIG. 15C.
DESCRIPTION OF THE INVENTION
[0020]
　Hereinafter, embodiments of the present invention will be described. As will be described by way of example embodiments of the present invention in the following description, the present invention is not limited to the examples described below. There is a case to illustrate specific numerical values ​​and materials in the following description, as long as the effect of the present invention are obtained, may be applied other numerical values ​​and materials.
[0021]
　(Method for producing a metal shaped article)
　producing process of the present invention is a method for producing a metal shaped article comprising a tubular portion having a slit. The matters described in the production method of the present invention, the present invention, metal moldings, can be applied to the manufacturing equipment, and mold.
[0022]
　Metal formed article may include a portion other than the tubular portion having a slit. Alternatively, a metal molded article may be constituted by only the tubular section having a slit. The metal molded article in this case is a molded article of tubular having a slit. It will be described later examples of the metal formed article to be produced. Production method of the present invention includes a step to be described below (i) and step (ii).
[0023]
　(Step (i))
　In the step (i), by deforming a metal plate, cross section form a U-shaped portion is U-shaped. There is no particular limitation to the step (i), it may be applied to U shaped to that used in conventional UO forming. As the method of U shaped it is not particularly limited as long as it cross-section can be molded a metal plate so that the U-shape. Examples of U molding, press molding include roll forming or the like. U molding may be carried out in multiple steps. Further, before the U shaped, machined to bend the end of the metal plate (work of so-called C molding) may be performed. Further, after the U shaped, it may be carried out trimming of the U-shaped portion (cutting).
[0024]
　In this specification, unless otherwise noted, the cross section of the tubular portion, means a circumferential cross-section of the tubular portion. In other words, the cross section of the tubular portion, the axial direction of the tubular portion (usually the longitudinal direction) means a section in a direction perpendicular to. U-shaped portion of the cross section, the cylindrical portion of the cross section is the same for the cross section of the pressing surface of the mold. Unless otherwise noted, the pressing surface of the die, of the mold, means a surface in contact with the outer peripheral surface of the cylindrical portion (or tubular portion). If the mold is composed of a plurality of members, the cross-sectional circumference of the pressing surface of the mold, means the sum of the cross-sectional length of the pressing surface of the plurality of members.
[0025]
　A metal plate which is molded by the manufacturing method of the present invention, the following may be referred to as "blank". Metal plate (blank) is not particularly limited as long as it can be molded. Examples of the metal plate include a steel sheet, for example, hot rolled steel sheets, cold-rolled steel sheet, and the like plated steel sheet. Further, examples of the metal plate include a metal plate obtained by connecting a plurality of metal plates (so-called tailored blanks) is. Tailored blanks, it may be one obtained by connecting a plurality of metal plates in the axial direction of the resulting tubular portion, or may be obtained by connecting a plurality of metal plates in the circumferential direction of the resulting tubular portion . Further, may also be used different thickness steel plate thickness differs depending on the location as a blank. Further, it may be used a so-called laminate blank. Examples of laminate, a superposition of the plurality of metal plates, and includes a superposition of non-metallic material in the metal plate. That is, the metal molded article may comprise a material other than the metal plate.
[0026]
　Metal plate (blank) is or thin metal plate may be a high-tensile steel plate (so-called high-tensile steel). Since these tend to spring back increases, the present invention is particularly useful. Examples of thin metal plates include those ratio of plate thickness for the equivalent diameter of the metal plate is 10% or less. Note that equivalent diameter is a value obtained by dividing the cross-sectional circumference of the tubular portion at 3.14. The tensile strength of the high-tensile steel is preferably at least 300 MPa, or may be a more 440 MPa (e.g. 490MPa or more and 780MPa or higher). There is no particular limitation to the upper limit of the tensile strength, it may be not more than 2000 MPa.
[0027]
　Material of the metal plate is not particularly limited as long as it can be molded. Examples of the material of the metal plate, Fe-based, Al-based, Cu-based, metal of Ti-based or the like.
[0028]
　There is no particular limitation on the thickness of the metal plate may be a moldable thickness. The thickness of the metal plate, the material of the metal plate, the shape of the metal formed article, is selected in consideration of the application of the metal formed article. In one example, the thickness of the metal plate is in the range of 0.4 ~ 5 mm (for example, a range within a scope and 1 ~ 3 mm of 0.5 ~ 3 mm) may be on.
[0029]
　The shape of the metal plate is selected according to the shape of the metal molded article of interest. As described below, in the manufacturing method of the present invention, the cross-sectional circumference LH of the tubular section is shorter than the sectional length LU of the U-shaped portion. Width W (length in the direction in which the circumferential direction in the tubular portion) of the portion to be the tubular portion of the metal plate is determined in consideration of the compressibility C which will be described later.
[0030]
　(Step (ii))
　In the step (ii), such that the two ends of the U-shaped portion to sandwich the protruding portion, by deforming the U-shaped part using a mold having a protruding portion, the slit a tubular portion having formed. In step (ii), the cross-sectional circumference LH of the tubular section is shorter than the LU sectional length of the U-shaped portion. Thereby, the metal plate constituting the tubular portion is compressed in the circumferential direction. As a result, the spring back of the tubular section is suppressed, it can be accurately controlled intervals of the slits. The gap between the two ends butted across the protrusions (two ends of the U-shaped portion) is slit. That is, the step (ii), a metal molded article comprising a tubular portion having a slit is produced. Of course, it may be further processed and the resulting metal molded article by step (ii).
[0031]
　The difference between the cross-sectional length LU of the cross-sectional circumferential length LH and the U-shaped portion of the tubular portion is preferably at least 0.2% of LU sectional length of the U-shaped portion. That is, the cross-sectional circumference LH sectional length LU and the tubular portion of the U-shaped portion, preferably satisfies 0.2 ≦ 100 × (LU-LH) / LU formula. If this difference is too small, the effect of suppressing the spring-back, and, the effect of forming a high precision tubular portion is not sufficiently obtained. Hereinafter, sometimes referred to as "100 × (LU-LH) / LU" the value of the compressibility of the tubular portion C (%). Compression ratio C of the tubular portion may be 0.5% or more.
[0032]
　From the viewpoint of suppressing buckling, the compression ratio C may be a 2%, may be less than 1%. By the compression ratio C and less than 1%, it can be further suppressed buckling. In particular, since the buckling easily occurs in the case where the thin metal plate, it is preferable that the compression ratio C and less than 1%. In a preferred example, 0.2 ≦ 100 × (LU-LH) / LU <1 expression is satisfied.
[0033]
　When the difference between the cross-sectional length LU of the cross-sectional circumferential length LH and the U-shaped portion of the tubular portion (LU-LH) is too large, (Orekomi metal plate) buckling or occurs, the upper and lower molds which may or metal plate sandwiched abutment. On the other hand, the thicker the metal plate, buckling even by increasing the compression ratio C is less likely to occur. Further, as the metal plate is thin, the effect obtained by the compression increases. In that respect, in consideration of the thickness of the metal plate, it is preferable to determine the difference between the cross-sectional length LU of the cross-sectional circumferential length LH and the U-shaped portion. For example, the thickness of the metal plate constituting the tubular portion when the t, the difference between the cross-sectional length LU of the cross-sectional circumferential length LH and the U-shaped portion of the tubular section may be less 8t. In this case, the difference between the cross-sectional length LU of the cross-sectional circumferential length LH and the U-shaped portion of the tubular portion may be more than 0.1 t.
[0034]
　In a preferred example, the compression ratio C is 0.2% or more, the difference between the cross-sectional circumferential length LH and cross-sectional length LU is less than 8t. In another preferred example, the compression ratio C is less than 2% 0.2%. A thin metal plate ratio of the plate thickness is not more than 5% of equivalent diameter of the metal plate (the equivalent diameter) Consider the case of using as a blank. In this case, the compression ratio C is preferably less than 1% of 0.2% or more (e.g. less than 0.2% 0.5%).
[0035]
　From the standpoint of preventing buckling, metal plate yield stress of (blank) sigma (MPa) and sheet thickness t (mm) may be determined compression rate C in consideration constituting the tubular portion. For example, the compression ratio C described above (%) may satisfy the following equation. In this case, as the lower limit of the compression ratio C, it may be employed any lower as described above. Although not limited to the thickness of the metal plate when satisfying the following formula may be in the aforementioned range (e.g. the range of 0.4 ~ 5 mm).
C ≦ (1500 / σ) × t
[0036]
　Step (ii) may comprise the following steps of (ii-1) and (ii-2). In step (ii-1), by deforming the U-shaped portion of two ends of the U-shaped section using a mold so as to sandwich the protruding portion, to form a tubular portion comprising a tubular portion. The cylindrical portion is a precursor of the finally obtained tubular portion in step (ii), it can be referred to as "first tubular portion" or "tubular portion precursors". In step (ii-2), by pressing the outer peripheral surface of the cylindrical portion in a state in which the two ends across the projections of the mold, to shorten the cross-sectional circumferential length LT of the cylindrical portion. The step (ii-2), the cross-sectional circumference LH of the tubular section is shorter than the LU sectional length of the U-shaped portion. That is, the step (ii-2), a metal plate constituting the tubular portion is compressed in the circumferential direction. After forming the cylindrical portion in the step (ii-1), by compressing the cylindrical portion in the circumferential direction in the step (ii-2), it is possible to perform stable compression. Specifically, it can be suppressed like buckling occurs during the formation of the tubular portion.
[0037]
　Three examples of step (ii) (Example (A), Example (B), and Example (C)) will be described below. Example (A) and Example (B) is an example including a step (ii-1) and (ii-2).
[0038]
　(Step (example ii) (A))
　a mold used in Example (A) (a), the following (a-1), has the structure of (a-2), and (a-3).
(A-1) mold (a) includes a first mold having a protruding portion and a second mold.
(A-2) first and second mold respectively, include first and second pressing surfaces for forming the cylindrical portion to deform the U-shaped portion.
(A-3) at least one mold selected from the first mold and the second mold can be separated into a plurality of mold members.
[0039]
　Respect to the configuration (a-3), both the first and second mold may be separable. Alternatively, only the first mold may be separable, only the second mold may be separable. If both the first and second mold are separable, the cross-sectional circumference LH tubular portion easier to fine-tune, as a result, the variation in the compressive stress acting on the tubular portion can be further reduced. As a result, it is possible to form more accurately slit. In an example where the first mold are separable, first mold can be separated into a first mold member and the second mold member. In this case, the projection portion may be constituted by a second protrusion included in the first projection and the second mold member included in the first mold member.
[0040]
　Example steps (A) (ii-1), to form the tubular portion by deforming the U-shaped part with a mold (a) in which a plurality of die member is separated. In the subsequent step (ii-2), it presses the outer peripheral surface of the cylindrical portion by approaching the plurality of die member, thereby shortening the cross-sectional circumferential length LT of the cylindrical portion. According to this structure, the metal plate constituting the tubular portion is compressed in the circumferential direction.
[0041]
　In a preferred example of embodiment (A), a mold (a) is moved only in the vertical direction in the step (ii-1), the mold in step (ii-2) (a) is moved only in the horizontal direction. For example, if only the upper die of the mold (a) is moved in the vertical direction (pressing direction) to move the upper die to a bottom dead center in the step (ii-1). Thereafter, in step (ii-2), a plurality of mold members are separated, it moved in the horizontal direction.
[0042]
　(Step (example ii) (B))
　Example (B) a mold used in (b), the following (b-1), has the structure of (b-2), and (b-3).
(B-1) mold (b) includes a first mold having a protruding portion and a second mold.
(B-2) first and second mold respectively, include first and second pressing surfaces for forming the cylindrical portion to deform the U-shaped portion.
(B-3) at least one mold selected from the first mold and the second mold includes a body portion and a relatively movable movable portion relative to the body portion.
[0043]
　Respect to the configuration (b-3), each of the first and second mold may comprise a movable portion. Alternatively, only the first mold may include a movable portion, only the second mold may comprise a movable portion. In one example, first and second mold each comprise first and second movable portion movable in the pressing direction (vertical direction). In that case, the first movable portion included in the first mold may include a protruding portion for forming a slit. In another example, at least one of the first and second mold includes first and second movable portion movable in a direction orthogonal to the pressing direction. First and second movable portion is disposed so as to face each other across the cylindrical portion. By pressing the outer peripheral surface of the cylindrical portion by the two movable portions (first and second movable portions), it can be compressed the cylindrical portion in the circumferential direction. Here, the pressing direction, the main body portion of the mold means in a direction to move the time of molding.
[0044]
　Example (B) of step (ii-1), to deform the U-shaped part using a mold in which a pressing surface of the movable portion does not protrude from the pressing surface of the main body portion. In the subsequent step of (ii-2) step, and presses the outer peripheral surface of the cylindrical portion by projecting the pressing surface of the movable portion from the pressing surface of the body portion, thereby shortening the cross-sectional circumferential length LT of the cylindrical portion . According to this structure, the metal plate constituting the tubular portion is compressed in the circumferential direction. In a typical process (ii-2), moving only movable portion without moving the main body portion.
[0045]
　(Step (ii example) (C))
　die used in Example (C) (c) has the following configuration.
(C-1) mold (c) includes a first mold having a protruding portion and a second mold.
(C-2) first and second mold respectively, include first and second pressing surfaces for forming the cylindrical portion to deform the U-shaped portion.
(C-3) cross-section perimeter of the mold pressing surface of (pressing surface of the first and second mold) is shorter than the sectional length LU of the U-shaped portion.
[0046]
　Unlike the mold (a) and the mold and (b), each of the first mold and the second mold constituting mold (c), an integral principle. However, it may be replaceable projections of the first mold. Example (C), to deform the U-shaped portion by only close the first mold and the second mold in step (ii), thereby forming a tubular portion having a slit. Example (C), the structure of the mold is simple, has the advantage of being easy to manufacture metal moldings.
[0047]
　In the production method of the present invention, the mold comprises a pressing surface corresponding to the outer peripheral surface of the tubular portion, and the cross section perimeter of the pressing surfaces may be shorter than the LU sectional length of the U-shaped portion. According to this configuration, by forming the tubular portion to press the outer peripheral surface of the U-shaped portion by the pressing surface of the die, the cross-sectional circumference LH of the tubular section than the cross-section length LU of the U-shaped portion It can be shortened. As described above, the mold (c) has the structure, with the structure as the mold (a) is also in principle. It said mold (b) may be have the construction or may not have. Note that the cross-sectional circumference of the pressing surface of the mold, means the sum of the cross-sectional length of the pressing surface of the plurality of members constituting the mold.
[0048]
　In case of using the mold (a) and (c), the case of forming a tubular portion having a slit by completely closing the mold, usually, cross-sectional circumference of the cross section circumference of the pressing surface of the mold and the tubular portion the length LH is considered not significantly different. In that case, in this specification, the cross-sectional circumference LH of the tubular section, it is possible to replace the cross-sectional circumference of the pressing surface of the mold. For example, in the formula and other formulas compression ratio C described above, the cross-sectional circumference LH of the tubular section, it is possible to replace the cross-sectional circumference of the pressing surface of the mold.
[0049]
　Step of the manufacturing method of the present invention (ii) is typically practiced without core, for example, the area of ​​most (e.g. the inner peripheral surface of the inner peripheral surface of the tubular portion (or the tubular portion) it may be carried out without using a core, such as contact with more than 50%) of. By performing the step (ii) without using a core, comprising a tubular portion is easily uniformly compressed in the circumferential direction. When using a core, interposed metal plate between the mold and the core are less likely to be compressed in the circumferential direction. However, if desired, may be used a core in the step (ii). By using a core, the circumferential direction of the cross-sectional shape can be stably formed a complex metal moldings. For example, in the case where θ angle shown in FIG. 1 to be described later exceeds 180 °, for the stable molding, it may be used a core. When using a core, the core may be arranged throughout the portion serving as the tubular portion may be disposed only on a part of the portion to be the tubular portion.
[0050]
　In the production method of the present invention, after the step (ii), it may be further processed metal formed article. For example, adding a projection or flat portion metal formed article may puncture the metal formed article.
[0051]
　Production method of the present invention is intended to produce a metal molded article comprising a tubular portion having a gap in the abutting portion. Therefore, in principle, after the step (ii), welding of the slit (portion abutting a gap) is not performed. However, a portion of the butt portion may be welded. For example, part of the butt portion is a gap (slit), if the other part does not have a gap, may be welded to part or all of the butt portion having no gap. In this case, it is preferable not to weld the butted portion with a gap. Incidentally, when assembling the product using a metal molded article, a part of the butt portion may be pre-welded.
[0052]
　(Metal molding)
　metal formed article of the present invention, includes a tubular portion having a slit. In one aspect, the tubular portion is a tubular portion having a gap in the abutting portion. Metal formed article of the present invention is manufactured by the manufacturing method of the present invention. It may be omitted from redundant explanation of the matters described elsewhere with respect to the metal formed article. The matters described for metal formed article of the present invention, the present invention can be applied to the manufacturing method, manufacturing apparatus, and mold.
[0053]
　Metal formed article of the present invention may comprise a portion other than the tubular portion having a slit. Alternatively, a metal molded article may be constituted by only the tubular section having a slit. The metal molded article in this case is a molded article of tubular having a slit. Slit is generally axially of the tubular portion (usually the longitudinal direction) are formed along the. Slits may be formed on the entire tubular portion may be formed only on a part of the tubular portion. In other words, metal molded articles, may have a slit over the entire length of the butted portion, only part of the butt portion may have a slit.
[0054]
　The shape of the tubular portion with slits, as long as they can be formed by the method of the present invention is not particularly limited. The shape of the cross section of the tubular portion is not particularly limited, circular, oval, or square, the shape of the vertically asymmetrical shape such as asymmetrical, it may be of various shapes. The tubular section may be a round tubular, it may be a square tubular.
[0055]
　Examples of the shape of the tubular portion, straight straight, curved bend, different-diameter pipe having an outer diameter different from the longitudinal direction, the cross-sectional shape in the longitudinal direction include different irregular cross section tube or the like. Specifically, examples of the tubular portion, 9A, 9B, 9C, includes a tube (tubular portion 1e) shown in FIGS. 9D and 9E,. In these tubes, the slits 3 in the abutting portion 2 is formed.
[0056]
　Tube shown in Figure 9A, the circumferential direction of the cross-sectional shape is a straight tube of circular. Tube shown in Figure 9B, the circumferential direction of the cross section is bent pipe is circular. Tube shown in FIG. 9C, the circumferential direction of the cross-sectional shape is trumpet-shaped cross-diameter tube is circular. Tube shown in FIG. 9D, the circumferential direction of the cross-sectional shape is irregular cross section tube that varies in a rectangular shape from a circular shape. Tube shown in Figure 9E, the circumferential direction of the cross-sectional shape is a tube in the form of a vertically asymmetrical and asymmetrical. Further, the tube shown in FIG. 9E is a tube formed by using a tailored blank that is spliced ​​to a different metal plate circumferentially.
[0057]
　Circumferential direction of the cross section tubes and in the form of asymmetrical tubes with tailored blank as illustrated in Figure 9E, it is difficult to mold in conventional UO forming. In contrast, by properly selecting the mold of the present invention, it is possible to mold the tube and of various shapes, a variety of blank.
[0058]
　Metal formed article of the present invention is obtained by molding a metal plate (blank). Therefore, the material of the metal formed article is the same as the material of the blank. In addition, the thickness of the metal formed article, approximately equal to the thickness of the blank. Therefore, (the thickness of the tubular section) the thickness of the metal formed article may be in the range exemplified as the plate thickness of the blank. Some of the physical properties of the metal formed article may vary from the physical properties of the blank in the machining process. In particular, a metal molded article of the present invention, since the tubular portion is compressed in the circumferential direction, whereby the physical properties are changed.
[0059]
　According to the production method of the present invention can produce metal molded article of the present invention. Metal formed article of the present invention, when representing a variation S of the plate thickness direction of the Vickers hardness in the cross section of the tubular section by the following equation, the average value of the circumferential variation S is less than 0.4 (0 or 0 it is less than .4).
　S = (Bmax-Bmin) / Bmax
, where, Bmin is the minimum value of the thickness direction of the Vickers hardness in the cross section of the tubular portion. Bmax is the maximum value of the thickness direction of the Vickers hardness in the cross-section.
[0060]
　The "circumferential direction of the mean value of the variation S" is the average value of the measured variation S for the three positions of one of the cross-section of the tubular portion (the circumferential direction of the cross section). Three positions to be measured, a first position of the slit near the tubular portion, the farthest the second position from the first position in the circumferential direction, the third position of the middle of the first position and the second position it is. Tubular portion is a circular tube, a case where the slit is positioned at the top of the tubular section. In this case, when the bottom of the tubular portion assuming 0 ° around the center of the tubular portion, first, respectively second, and third position is about 180 °, becomes 0 °, and 90 °. First position, the distance from the end facing the slits is set in a range of, for example, 5mm or less.
[0061]
　In the production method of the present invention, the cross-sectional circumference LH of the tubular section is shorter than the LU sectional length of the U-shaped portion. Therefore, it acts compressive stress throughout the thickness direction of the tubular portion, and is small variation in the compressive stresses acting in the circumferential direction of the tubular portion. Therefore, by forming the tubular portion in the manufacturing method of the present invention, in the entire cross section of the tubular portion can be increased Vickers hardness. As a result, in the entire area of ​​the cross section of the tubular portion, it is possible to reduce the variation in Vickers hardness. Reducing the variation in Vickers hardness is effective in improving the durability and reliability of the metal formed article having a tubular portion.
[0062]
　In a preferred example, all the variations S measured at three positions described above is less than 0.4 (e.g., less than 0.2). According to this arrangement, improvement in durability and reliability can be particularly expected.
[0063]
　(Method of measuring Vickers hardness)
　will be described below a method of measuring the Vickers hardness of the tubular portion. First, cutting the tubular portion in the circumferential direction and mechanically polishing the cut surface until a mirror surface. Next, in order to eliminate the influence of work hardening caused by mechanical polishing, chemical polishing or electrolytic polishing, to dissolve the cutting plane from the surface of the cut surface to a depth of 30 ~ 80 [mu] m. For cut surface thus obtained to measure the Vickers hardness.
[0064]
　Vickers hardness is measured according to the test method of Vickers hardness test of JIS Z 2244 of the Japanese Industrial Standards (JIS). The Vickers hardness test, to form a recess by pushing an indenter into a test piece, measuring the diagonal length of the indentation. When evaluating the variation S of the cut surface of the tubular section is measured by forming a plurality of recesses in the cutting plane. When the tubular part is made of steel, copper or a copper alloy, a distance 3d or between the centers of two adjacent depressions (the larger value in the diagonal length of d indentations) from the center of the depression specimen the distance to the edge of the (cut surface of the tubular portion) and more 2.5d. Tubular portion is light metal when made of (aluminum, aluminum alloys, titanium, titanium alloys, magnesium and magnesium alloy) is the distance between the centers of two adjacent recesses and 6d above, from the center of the depression of the specimen the distance to the edge and 3d above. These distances may be adjusted by the force pushing the measurement interval and indenter of Vickers hardness.
[0065]
　For the first position described above, measuring the Vickers hardness at 5 points existing at equal intervals in the thickness direction of a straight line. Then, to determine the minimum value Bmin and maximum value Bmax of the Vickers hardness from the measured values ​​of the five points, obtaining the variation S as described above. For the second and third positions described above also obtains a variation S described above was similarly measured Vickers hardness. Then, by averaging the three variations S obtained, the average value of the circumferential variation S is obtained.
[0066]
　Metal formed article of the present invention can be utilized in various applications. Examples of the metal formed article applications, various vehicles (automobiles, railway vehicles, other vehicles) parts (underbody parts, body, structural materials, etc.), various machines, electronic equipment, parts appliances, various of transport (ship, aircraft), and the like parts.
[0067]
　(Manufacturing apparatus)
　manufacturing apparatus of the present invention is a manufacturing apparatus for manufacturing a metal molded article comprising a tubular portion having a slit. The production apparatus may be utilized in the production method of the present invention. This manufacturing apparatus can manufacture a metal formed article of the present invention. This manufacturing apparatus, in another aspect a press apparatus, the configurations that are not described below, may be applied the configuration of the known press machine. It may be omitted from redundant explanation of the matters described elsewhere with respect to the manufacturing apparatus. The matters described manufacturing apparatus of the present invention, the present invention can be applied production method, metal moldings, and the mold.
[0068]
　Manufacturing apparatus of the present invention comprises a mold, a moving mechanism for moving the mold. Mold includes a first mold and a second mold. The first mold includes a protrusion for forming the slit. The first and second mold section comprises a first and a second pressing surface to form a cylindrical portion having a gap to be slit to deform the U-shaped portion is U-shaped . Mold has a configuration for cross circumference LT of the cylindrical portion presses the outer peripheral surface of the cylindrical portion to be shorter.
[0069]
　Hereinafter, two examples of the manufacturing apparatus of the present invention (producing apparatus (a) and production equipment (b)) will be described.
[0070]
　(Manufacturing equipment (a))
　manufacturing equipment (a), the above-mentioned mold (a) is used. As described above, the mold (a), the following (a-1), has the structure of (a-2), and (a-3).
(A-1) mold (a) includes a first mold having a protruding portion and a second mold.
(A-2) first and second mold respectively, include first and second pressing surfaces for forming the cylindrical portion to deform the U-shaped portion.
(A-3) at least one mold selected from the first mold and the second mold can be separated into a plurality of mold members.
[0071]
　Moving mechanism of the manufacturing apparatus (a) includes a first moving mechanism and a second moving mechanism. The first moving mechanism is a first mold and a moving mechanism for approximating the second mold in a state in which a plurality of mold members are separated. Usually, the first moving mechanism in a state where a plurality of die member are separated, close to the first mold and the second mold is in contact with the first mold and the second mold make. Second moving mechanism is a moving mechanism for approximating plurality of mold members are separated. First moving mechanism corresponds to the step (ii-1) of the example described above (A). Second moving mechanism corresponds to the process of Example (A) (ii-2). According to the manufacturing apparatus (a), can be carried out step (ii) of the above-described example (A).
[0072]
　First die of the mold (a) may be separable into a first mold member and the second mold member. In that case, projections for forming the slits, may be constituted by the second protruding portions included in the first projection and the second mold member included in the first mold member .
[0073]
　(Manufacturing apparatus (b))
　production apparatus (b), the above-mentioned mold (b) is used. As described above, the mold (b), the following (b-1), has the structure of (b-2), and (b-3).
(B-1) mold (b) includes a first mold having a protruding portion and a second mold.
(B-2) first and second mold respectively, include first and second pressing surfaces for forming the cylindrical portion to deform the U-shaped portion.
(B-3) at least one mold selected from the first mold and the second mold includes a body portion and a relatively movable movable portion relative to the body portion.
[0074]
　Moving mechanism of the manufacturing apparatus (b) includes a first moving mechanism and a second moving mechanism. The first moving mechanism is a first mold and a moving mechanism for approximating the second mold. Usually, the first moving mechanism in a state where the pressing surface of the movable portion does not protrude from the pressing surface of the body portion, the first mold to the first mold and the second mold are in contact the to approach the second mold. Second moving mechanism is a moving mechanism for the pressing surface of the movable portion moves the movable portion so as to protrude from the pressing surface of the main body portion. First moving mechanism corresponds to the step (ii-1) of the example described above (B). Second moving mechanism corresponds to the step (ii-2) of Example (B). According to the manufacturing apparatus (b), it can be carried out step (ii) of the above-described example (B).
[0075]
　Whenever possible the above operation is not particularly limited to the configuration of the moving mechanism of the manufacturing apparatus (a) and (b), may be applied a known movement mechanism that is used in the press apparatus of the double-acting . For example, the moving mechanism of the manufacturing apparatus (a) and (b) respectively, may be combined with extension mechanism or a cam. Examples of the telescopic mechanism includes a gas cylinder, a hydraulic cylinder, a spring and the like.
[0076]
　A manufacturing apparatus for carrying out the step (ii) of the above-described example (C) is not particularly limited but using mold (c). Step of Example (C) (ii) may be performed in a general press.
[0077]
　(Mold)
　mold of the present invention is a mold for manufacturing a metal molded article comprising a tubular portion having a slit. This mold can be utilized in the manufacturing apparatus of the present invention. Further, the mold can be used for the production method of the present invention, specifically available in step (ii) of the manufacturing method of the present invention. By using this mold can be manufactured of metal molded article of the present invention. It may be omitted from redundant explanation of the matters described elsewhere with respect to the mold. The matters described for the mold of the present invention, the present invention can be applied production method, metal moldings, and the manufacturing apparatus.
[0078]
　Mold of the present invention includes a first mold including a protrusion for forming a slit, and a second mold. The first and second mold section comprises a first and a second pressing surface to form a cylindrical portion having a gap to be slit to deform the U-shaped portion is U-shaped . When the outer periphery of the cross-section to form a circular cylindrical portion (or tubular portion), a second pressing surface has a semi-cylindrical shape, the first pressing surface, except for the protrusion semicircle having a columnar shape.
[0079]
　Mold of the present invention has a structure for sectional circumference of the tubular portion presses the outer peripheral surface of the cylindrical portion to be shorter. In another aspect, the mold of the present invention has a structure for compressing a cylindrical portion in the circumferential direction. Examples of the mold of the invention includes the above-mentioned mold (a) and the mold (b).
[0080]
　The first mold is used as the upper die having a protrusion, the second mold may be used as the lower mold. Therefore, in this specification, read as upper mold a first mold, a second mold may be replaced with the lower mold. Also, read as the lower mold a first mold, a second mold may be read as an upper mold.
[0081]
　Protrusions have a formable shape slit. Along the axial direction of the tubular portion by using a first mold plate-like protrusions are arranged to form a slit along the axial direction of the tubular portion. In a typical example, the protrusion is a plate-like protruding portion, of the semicircular pressing surface of the upper die is provided on its uppermost position. In other words, in a typical example, the protrusion in the center of the cross section of the upper mold pressing surface (circumferential direction of the cross section) is provided. However, the protrusion is not limited to the central portion, it may be in a position shifted from the center. For example, in the case of forming a tubular portion of the asymmetric, the projection portion may be in a position shifted from the central portion. Protrusions position in the circumferential direction, may vary along the axial direction. The width of the protrusion may vary along the axial direction. By using projections which changes in the axial direction, a slit which changes in the axial direction.
[0082]
　The inner diameter of the tubular portion and Din, the thickness is taken as t, the width of the slit is at least t (Din-2t) may be less. If the width of the slit is less than t, there is a possibility that the strength of the protrusion of the mold is insufficient. If the width of the slit is larger than (Din-2t), there are cases where the effect of the invention is reduced.
[0083]
　The width of the protrusion is selected according to the width of the slit (gap of the butted portion). The width of the protrusion is preferably within ± 10% of the width of the slit.
[0084]
　As described above, in the mold (a), at least one mold selected from the first mold and the second mold is separable into a plurality of mold members. When the number of the die member is large, U-shaped portion between the mold member adjacent to the time of molding may become easily caught. Further, the number of die member is large, the structure of the mold and apparatus using the same is complicated. Therefore, in a preferred example of the case where the first mold is divided into a plurality of die member, the first mold is divided into two die member. Similarly, in a preferred example of a case where the second mold is divided into a plurality of die member, the second mold is divided into two die member.
[0085]
　If the first die and / or the second die is separable into a plurality of mold members, there is no particular limitation on the position of the separation. When the first mold is separable into a first mold member and a second mold member, protrusion, the first protrusion and the second metal contained in the first mold member it may be configured by the second protruding portion included in the mold member. That is, the first mold part of the protruding portion may be divided. According to this arrangement, the first and second protrusions can guide the two ends of the U-shaped section, that the ends of the U-shaped portion is inserted between the two mold members It can be prevented.
[0086]
　In the mold (a), by moving a plurality of die member separately, the cross-sectional circumference LH of the tubular section can be easily finely adjusted, it is possible to reduce the variation in the compressive stress acting on the tubular portion. Therefore, according to the mold (a), the spring-back can be effectively suppressed, as a result, can be formed accurately slit.
[0087]
　As described above, in the mold (b), at least one mold selected from the first mold and the second mold includes a body portion, movable relative movable portion relative to the body portion including the door.
[0088]
　In the mold (b), only the first mold may have a main body portion and a movable portion, only the second mold may have a main body portion and a movable portion. Alternatively, both the first and second mold respectively, may have a body portion and a movable portion. If each of both of the mold has a main body portion and the movable portion can increase the area of ​​the pressing surface of the movable portion, so that when compressing by pressing the cylindrical portion in the circumferential direction, stable It can be pressed Te.
[0089]
　Position the movable portion is disposed, it is as long as there is no particular limitation position capable of adjusting the cross-sectional circumference of the tubular section by moving the movable portion. For example, the movable portion may be disposed at a position corresponding to the top and bottom of the tubular portion may be disposed at positions corresponding to the two sides of the tubular section. The movable portion is preferably arranged so as to correspond to the two positions facing each other across the center of the tubular portion.
[0090]
　The movable portion is disposed at least in a region Example (B) of step (ii) is carried out. For example, the movable portion may be disposed over the entire length of the mold, it may be disposed only on a part of the mold.
[0091]
　When the first mold has a body portion and a movable portion, the number of the movable portion may be plural and may be one. When the movable portion is plural, as compared with the case the movable part is one, easily fine-tune the cross-sectional circumference of the tubular portion. Similarly, if the second mold having a body portion and a movable portion, the number of the movable portion may be plural and may be one. If the movable portion is plural, it may be arranged movable portion at both locations corresponding to the side position and a cylindrical portion corresponding to the top portion of the cylindrical portion (or bottom).
[0092]
　Moving part, so as to move relative to the main body portion, it can be moved by a cylinder or a cam mechanism or the like.
[0093]
　The mold of the present invention, protruding portions for forming the slit may be replaceable. For example, the above-mentioned mold (a), (b), and (c), the protrusions may be replaceable. Since the protruding portions easily depleted, you can lengthen the mold life by a replaceable projections. Further, by replacing the protruding portion, it becomes easy to adjust the width of the slit. When the physical properties of the metal plate (blank) (tensile strength, etc.) and thickness is changed, the amount of spring back is changed. Therefore, in the conventional method, it was necessary to change the entire mold each time a change in physical properties and thickness of the metal plate. However, by enabling exchange projections, it becomes easy to adjust the width of the slit without changing the entire mold.
[0094]
　Mold shape are designed properly depending on the shape of the tubular portion of interest. For example, as shown in FIG. 8, the circumferential direction of the cross-sectional shape of the pressing surface of the mold may be in the form of vertically asymmetrical, it may be in the form of asymmetrical. Circumferential direction of the cross-sectional shape of the pressing surface of the mold may be a constant over the axial direction, it may vary in the axial direction. The pressing surface of the die may be a straight axially may be bent in the axial direction.
[0095]
　Each of the first mold and the second mold may be a single-acting. Each of the first mold and the second mold may be double acting if necessary. Mold (a) and (b), at least one selected from the first and second mold is double-acting. By using a mold of double-acting, it is possible to finely adjust the cross-sectional circumference of the tubular portion, it is possible to reduce the variation in compressive stress acting on the cylindrical portion. Therefore, the spring back can particularly effectively suppressed, it is possible to improve especially the accuracy of shape of seniority moldings. If the mold is double acting, the manufacturing apparatus using the same, and mechanism for use in a press apparatus of the double-acting mechanism using such as a cylinder or a cam is used.
[0096]
　If the material and thickness of the metal plate is changed, the amount of spring back is changed accordingly. Therefore, in the molding method using the conventional mold, if the material and thickness of the metal plate is changed, it is necessary to change the mold accordingly. On the other hand, in the mold of the present invention, it is possible to vary the compression ratio of the tubular portion without changing the mold. For example, in a mold (a), it is possible to vary the compression ratio of the tubular portion by the distance between the plurality of mold members. In the mold (b), it is possible to vary the compression ratio of the tubular section by changing the movement amount of the movable portion. Therefore, in the mold of the present invention, even when the material and thickness of the metal plate is changed, without changing the mold, it is possible to control the spacing of the slits. Therefore, the mold of the present invention is suitable for mass production of the metal molded article of the present invention.
[0097]
　As described later, by using a mold of the present invention, the tubular portion, the variation in the hardness distribution in the dispersion and the circumferential direction of the hardness distribution in the sheet thickness direction can be reduced. Therefore, by using a mold of the present invention can be produced having a high fatigue strength metal formed article.
[0098]
　In the following, an example embodiment of the present invention will be described with reference to the drawings. In the following description, it may be omitted from redundant explanation are denoted by the same reference numerals to like parts.
[0099]
　(First Embodiment)
　In the first embodiment, an example of a metal formed article of the present invention. Metal formed article of the present invention, it includes a tubular portion having a slit. The cross section in a direction perpendicular to the axial direction of the tubular portion (the circumferential direction of the cross section), shown schematically in FIG. 1. Metal formed article 1 comprises a tubular portion 1e of the slit 3 is formed, typically composed of only the tubular portion 1e. In the slit 3, the two ends E1 and E2 are butted. In another aspect, the metal molded article 1 is a schematic closed cross-section part (tubular part having a substantially closed cross section). Here, "substantially closed cross-section" refers to a cross-section and there is a gap between the two ends which is abutted with the metal plate that is formed into a tubular shape. Substantially closed section part may have a gap over the entire length of the butted portion may have gaps in a part of the butt portion.
[0100]
　Here, assume two ends E1, E2 point separated by 3mm circumferentially along the tubular portion 1e from P1, P2. The point of intersection between the tangent line in the tangential and the point P2 at the point P1 and O. The angle θ formed by the line OP1 and the line OP2, is preferably 30 ° or more. If the angle θ is too small, almost no difference between the cross section of the U-shaped portion, the strength (bending strength) of the tubular portion after the molding may be lowered. A typical example is the angle θ of a 150 ° or more (e.g. 170 ° or higher). It is preferred that the angle θ is 180 ° or less. If the angle θ is too large, molding may become unstable.
[0101]
　(Second Embodiment)
　In the second embodiment, an example of a manufacturing method and the mold used therefor of the present invention. In the following embodiments, an example in the case of producing a metal molded article comprising only a tubular portion. Manufacturing method of the second embodiment includes a step (i) and step (ii).
[0102]
　Step a (i), schematically shown in FIGS. 2A and 2B. First, as shown in FIG. 2A, placing a metal plate (blank) 1a between the die 11 and the punch 12. Die 11 and punch 12 are mold for U shaped. Next, as shown in FIG. 2B, the metal plate 1a by press-forming, cross-section to form a U-shaped U-shaped portion 1b. As shown in FIG. 2C, U-shaped portion 1b has two ends E1 and E2.
[0103]
　In step (i), the width W of the portion to be the tubular portion (tubular portion 1e) of the metal plate, the magnitude relation between the cross-sectional length LU of the U-shaped portion 1b, various conditions (the shape of the tubular portion, It varies with step (i) conditions of). By their condition, when cross-sectional length LU is longer than the width W, it may be the case if the cross-sectional length LU is short, and they are equal than the width W. In the production method of the present invention, in step (ii), it is important that the cross-sectional circumference LH of the tubular section to form a tubular portion to be shorter than LU sectional length of the U-shaped portion. Therefore, there is no particular limitation on the relation between the width W and the sectional length LU in step (i).
[0104]
　Figure 3A, shows a mold used in the step (ii) of the second embodiment schematically. The die 20 of the second embodiment is an example of the above-mentioned mold (a). Mold 20 includes an upper die (first die) 21 and a lower mold (second mold) 22.
[0105]
　Upper die 21 has a plate-like projection 23 for forming the slit. Upper mold 21 includes a horizontal direction a first upper die can be separated (first mold member) 21a and a second upper die (second die member) 21b. Projection 23 is constituted by the second protruding portion 23b included in the first protruding portion 23a and the second upper die 21b included in the first upper die 21a. Lower mold 22 includes a horizontal direction the first lower mold can be separated (first mold member) 22a and a second lower mold (second mold member) 22b.
[0106]
　Upper die 21 has a first pressing surface 21p for forming the cylindrical portion 1d and presses the outer peripheral surface of the U-shaped portion 1b. The lower mold 22 has a first pressing surface 22p for by pressing the outer peripheral surface of the U-shaped portion 1b to form a tubular portion 1d (FIG. 3D). Protrusions 23 is a plate-like protrusion whose length is equal to or longer than the slit 3 formed. Sectional circumference of the whole pressing surface of the mold 20 (first pressing surface 21p and a second pressing surface 22p) is shorter than the LU sectional length of the U-shaped portion 1b.
[0107]
　For the next step (ii), will be described with reference to FIG. 3B ~ Figure 3E. Step of the second embodiment (ii) is a step of the above-described example (A), comprising the step (ii-1) and step (ii-2). According to step (ii), the U-shaped portion 1b, can be formed a tubular portion 1e having a slit.
[0108]
　In step (ii) of the second embodiment, first, as shown in FIG. 3B, placing the U-shaped portion 1b in the mold 20. Next, as shown in FIG. 3C and 3D, end E1 and the end portion of the U-shaped portion 1b E2 (Figure 2C see) and is U-shaped by using a mold 20 in a state of sandwiching the projecting portion 23 deforming the part 1b (step (ii-1)). Specifically, close both to the upper die 21 and lower die 22 are in contact, the outer peripheral surface of the U-shaped portion 1b is pressed by the pressing surface of the die 20. Step (ii-1) has a first upper die 21a and the second upper die 21b is separated in the horizontal direction, a first lower die 22a and the second lower die 22b is separated in the horizontal direction It is carried out in to that state. In this state, closer to each other by moving the upper die 21 and / or the lower mold 22 in the vertical direction. The step (ii-1), the tubular portion 1d is formed. In the process shown in FIG. 3C, the U-shaped portion 1c is deformed U-shaped part 1b. At this time, the two ends of the U-shaped portion 1c stops when the protrusion 23, a gap is generated between the two ends. The gap is the slit 3 of the tubular portion 1e. In the state of FIG. 3D, the end E1 and the end E2, we are opposed to each other across the protruding portion 23 (protruding portions 23a and 23b).
[0109]
　In the manufacturing method of the second embodiment, in the state of FIG. 3D, the cross-sectional circumferential length LT of the cross-section length and the cylindrical portion 1d of the U-shaped portion 1b may be substantially equal. This arrangement is a spacing between the first upper die 21a and the second upper die 21b, and can be realized by adjusting the distance between the first lower mold 22a and the second lower die 22b. According to this arrangement, when forming the cylindrical portion 1d by greatly deform the U-shaped portion 1b, it can be suppressed compressive force is applied in the circumferential direction. Therefore, it is possible to suppress the like buckling occurs during the formation of the tubular portion 1d. Here, the substantially equal, means that the difference between the length is a longer length, for example less than 0.1% (e.g., less than 0.05%).
[0110]
　Next, as shown in FIG. 3E, by the end E1 and E2 of the U-shaped portion 1b presses the outer peripheral surface of the cylindrical portion 1d in a state sandwiching the projecting portion 23, the cylindrical portion 1d the cross-sectional circumferential length LT shorter (step (ii-2)). Specifically, by closing the mold 20 which is divided, to reduce the cross-sectional circumferential length LT. More specifically, by moving the first upper die 21a and a second upper die 21b in the horizontal direction close to each other, the movement of the first lower die 22a and a second lower mold 22b in the horizontal direction It is to close them together. In the example shown in FIG. 3E, a first upper die 21a and the contacts second upper die 21b, a first lower die 22a and the second lower die 22b are brought close them until contact. That is, in the example shown in FIG. 3E, the pressing surface of the die 20 in a fully closed state corresponds to the outer peripheral surface of the tubular portion 1e. By shortening the cross-sectional circumferential length LT of the cylindrical portion 1d in the step (ii-2), the cross-sectional circumference LH tubular portion 1e can be made shorter than the LU sectional length of the U-shaped portion 1b. In this way, the tubular portion 1e (metal molding) as shown in FIG. 3F is obtained. The butted portion 2 of the tubular portion 1e, the slits 3 are formed.
[0111]
　In FIG. 3E, the die in the final stage of the molding shows the case completely closed. However, in the manufacturing method of the present invention, as long as the cross-sectional circumference LH tubular portion 1e becomes shorter than LU sectional length of the U-shaped portion 1b, it may die not completely closed at the final stage of molding. The extent Close the mold, it is possible to vary the compression ratio C as described above. Further, even when the thickness and physical properties of the metal plate 1a is changed, there is a case that can be supported by the extent Close the mold 20 in opening degree of the die 30 or, and 3E in FIG 3D. Therefore, even when the thickness and physical properties of the metal plate 1a is changed, it may be possible to produce the desired tubular portion 1e without changing the mold. Furthermore, the extent Close the mold 20 in FIG. 3E, it is also possible to vary the width of the slit 3.
[0112]
　When produced tubular components by conventional UO forming, in the inner peripheral side of the resulting tubular components act compressive stress, tensile stress acts in the outer peripheral side. Therefore, spring back increases, the control of springback is difficult. In contrast, in the manufacturing method of the present invention, the cross-sectional circumference LH tubular portion 1e shorter than the cross-section length LU of the U-shaped portion 1b. That is, in the manufacturing method of the present invention to obtain a tubular portion 1e compresses the tubular portion 1d in the circumferential direction. As a result, the tubular portion 1e, compressive stress acts on both the inner periphery side and the outer peripheral side. Therefore, the spring-back is suppressed, the slit 3 can be accurately formed.
[0113]
　In the production method of the present invention, to form a tubular portion 1e by compressing the cylindrical portion 1d in the circumferential direction. Therefore, the tubular portion 1e, compressive stress acts on both the inner periphery side and the outer peripheral side. Furthermore, the tubular portion 1e, the variation in the circumferential direction of the compressive stress can be reduced. As a result, the tubular portion 1e, the hardness distribution in the sheet thickness direction, and can reduce variations in the hardness distribution in the circumferential direction. Therefore, according to the present invention, it is possible to fatigue strength obtain high tubular portion.
[0114]
　In the manufacturing method of the second embodiment, all of the mold members existing around the cylindrical portion 1d are moved relative to compress the cylindrical portion 1d. Therefore, according to the manufacturing method and the mold of the second embodiment, it is possible to uniformly compress the cylindrical portion 1d in the circumferential direction. Therefore, the spring-back can be effectively suppressed, the shape accuracy of the tubular portion can be further enhanced.
[0115]
　(Third Embodiment)
　In the third embodiment, explaining another example of the manufacturing method and the mold used therefor of the present invention. Manufacturing method of the third embodiment includes a step (i) and step (ii). Step (i) is the same as process described in the second embodiment (i), without redundant description.
[0116]
　Figure 4A, shows a mold used in the third embodiment of step (ii) schematically. Mold 30 of the third embodiment is an example of the above-mentioned mold (b). Mold 30 includes an upper die (first die) 31 and a lower mold (second mold) 32.
[0117]
　The upper die 31 has a plate-like projection 33 for forming the slit 3. The upper die 31 includes a body portion 31a, and a relatively movable movable portion 31b with respect to the body portion 31a. The movable portion 31b is placed on top of the pressing surface 31ap of the main body portion 31a, including the projections 33. Lower mold 32 includes a body portion 32a, and a relatively movable movable portion 32b with respect to the body portion 32a. The movable portion 32b is disposed on the bottom of the pressing surface 32ap of the main body portion 32a. In the mold 30 of the third embodiment, both of the movable portions 31b and 32b is movable in the pressing direction (vertical direction). The movable portion 31b can be moved in the pressing direction integrally with the body portion 31a. The movable portion 32b can be moved in the pressing direction integrally with the body portion 32a.
[0118]
　In the mold of the present invention (b), in principle, a body portion and a movable portion can be moved in the pressing direction as a unit. Further, the mold of the present invention (b), in principle, the end face (end face facing the molding space) of the movable portion constitutes a part of the pressing surface, such as a roll is not disposed. Furthermore, the mold of the present invention (b), in principle, the movable portion in a state the first and second body portion is in the final position of the molding (dead point) is movable.
[0119]
　Each body portion 31a and the main body portion 32a, including the pressing surface 31ap and 32ap for forming the cylindrical portion 1d and presses the outer peripheral surface of the U-shaped portion 1b. Movable portions 31b and 32b, includes a pressing surface 31bp and 32bp presses the outer peripheral surface of the U-shaped portion 1b. The pressing surface 31ap and the pressing surface 31bp constituting the pressing surface 31p of the upper die 31. The pressing surface 32ap and the pressing surface 32 bp, constitute a pressing face 32p of the lower die 32. In one example described in the third embodiment, the cross-sectional circumference of the whole pressing surface is longer than the cross-sectional circumference LH tubular portion 1e. Sectional circumference of the whole pressing surface may be substantially equal to the LU sectional length of the U-shaped portion 1b.
[0120]
　For the next step (ii), will be described with reference to FIG. 4B ~ Figure 4E. Third embodiment of step (ii) is a step of the example described above (B), comprising the step (ii-1) and the step (ii-2). According to step (ii), the U-shaped portion 1b, can be formed a tubular portion 1e having a slit.
[0121]
　In step (ii) of the third embodiment, first, as shown in FIG. 4B, to place the U-shaped portion 1b in the mold 20. Next, as shown in FIG. And FIG. 4C 4D, the ends E1 and the end portion of the U-shaped portion 1b E2 (Figure 2C see) and by using the die 30 in a state of sandwiching the projecting portion 33 the U-shaped deforming the part 1b (step (ii-1)). Specifically, close both to the upper die 31 and lower die 32 are in contact, the outer peripheral surface of the U-shaped portion 1b is pressed by the pressing surface of the die 30. Step (ii-1) is the pressing surface 31bp and 32bp of the movable portion 31b and 32b is performed in a state that does not protrude from the pressing face 31p and 32p of the body portion. The step (ii-1), the tubular portion 1d is formed. That is, in the example shown in FIG. 4D, the pressing surfaces 31p and 32p corresponds to the outer peripheral surface of the cylindrical portion 1d. In the step of FIG. 4C, the U-shaped portion 1c is deformed U-shaped part 1b. At this time, the two ends of the U-shaped portion 1c stops when the protrusion 33, a gap is generated between the two ends. The gap is the slit 3 of the tubular portion 1e. In the state of FIG. 4D, the end E1 and the end E2, we are opposed to each other across the protruding portion 33.
[0122]
　In the manufacturing method of the third embodiment, the cross-sectional circumference of the whole pressing surface of the mold 30 may be equal cross-section, length LU substantially U-shaped portion 1b. In this case, when forming the cylindrical portion 1d by greatly deform the U-shaped portion 1b, it can be suppressed compressive force is applied in the circumferential direction. Therefore, it is possible to suppress the like buckling occurs during the formation of the tubular portion 1d.
[0123]
　Next, as shown in FIG. 4E, by the end E1 and E2 of the U-shaped portion 1b is in a state sandwiching the projecting portion 33 presses the outer peripheral surface of the cylindrical portion 1d, the cylindrical portion 1d shortening the cross-sectional circumferential length LT (step (ii-2)). Specifically, the pressing surface of the movable portion 31b and 32b, presses the outer peripheral surface of the cylindrical portion 1d by protrude from the pressing surface of the body portion 31a and 32a. In the third embodiment, of the cylindrical portion 1d, it presses the position opposing to the slit 3 to it from above and below. By shortening the cross-sectional circumferential length LT of the cylindrical portion 1d in the step (ii-2), the cross-sectional circumference LH tubular portion 1e shorter than LU sectional length of the U-shaped portion 1b. In this way, the tubular portion 1e (metal molding) as shown in FIG. 4F is obtained. The butted portion 2 of the tubular portion 1e, the slits 3 are formed.
[0124]
　Also in the manufacturing method of the third embodiment, the tubular portion 1e is formed by compressing the cylindrical portion 1d in the circumferential direction. Therefore, as described in the second embodiment, the slit 3 can be accurately formed. In the manufacturing method of the third embodiment, by changing the movement amount of the movable portion, it is possible to easily vary the compression ratio as described above. Therefore, even when the thickness and physical properties of the metal plate 1a is changed, it may be possible to the manufacturing method of the desired tubular portion 1e without changing the mold. Further, in the mold of the third embodiment, since it is possible to replace the protruding portion 33 by replacing the movable part 31b, it is easy replacement of the protrusion 33.
[0125]
　In the manufacturing method of the third embodiment, for compressing by pressing the cylindrical portion 1d by the movable portion, the cylindrical portion 1d is compressed in a state a small contact area between the cylindrical portion 1d mold 30. In this case, the compression force applied to the circumferential direction by the movable portion, easily applied to the whole of the cylindrical portion 1d. Therefore, according to the manufacturing method and the mold of the third embodiment, it is possible to uniformly compress the tubular portion 1d by the circumferential direction.
[0126]
　With reference to FIGS. 14A ~ FIG 14E, a description will be given of an example of manufacturing device be used in the step (ii) of the third embodiment. The manufacturing apparatus includes a first support base 141, a second support platform 142, telescopic mechanism 141a, and a telescopic mechanism 142a. The first support base 141, extension mechanism 141a and the movable portion 31b is disposed. Telescopic mechanism 141a is stretchable in the pressing direction, to press the body portion 31a. The second support bars 142, telescopic mechanism 142a and the movable portion 32b is disposed. Telescopic mechanism 142a is stretchable in the pressing direction, for supporting the main body portion 32a. Stretch mechanism limited to 141a and 142a is no gas cylinder, a hydraulic cylinder, it may be a spring.
[0127]
　In step (ii) of the third embodiment, first, as shown in FIG. 14A, placing the U-shaped portion 1b in the mold 30. Next, as shown in FIGS. 14B and 14C, closer to the first support base 141 and a second support platform 142. This performs the above-described steps (ii-1), to obtain a tubular portion 1d. Next, as shown in FIG. 14D, further closer to the first support base 141 while compressing the telescopic mechanism and a second support platform 142. Thus, as shown in FIG. 14D, the pressing surface of the movable portion 31b and 32b protrudes from the pressing surface of the body portion 31a and 32a, to press the outer peripheral surface of the cylindrical portion 1d. In this way, the step (ii-2) is performed.
[0128]
　In the apparatus shown in FIG. 14A, a mechanism closer to the first support base 141 and the second support bars 142 (not shown), and the expansion mechanism 141a and extension mechanism 142a in a state in which no stretching is, above manufacturing apparatus corresponding to the first moving mechanism (b). Also, a mechanism to approach the first support base 141 and a second support platform 142, a telescopic mechanism 141a and telescoping mechanism 142a of telescoping state corresponds to the second moving mechanism. Thus, in the mold (a) and (b), the same component members, may also serve as the first moving mechanism and a second moving mechanism. These moving mechanism may be achieved by using to suit the manufacturing apparatus of the present invention the moving mechanism of a known press machine.
[0129]
　(Fourth Embodiment)
　In the fourth embodiment, explaining another example of the manufacturing method and the mold used therefor of the present invention. Manufacturing method of the fourth embodiment includes a step (i) and step (ii). Step (i) is the same as process described in the second embodiment (i), without redundant description.
[0130]
　Figure 5A, shows a mold used in the step (ii) of the fourth embodiment schematically. Mold 30 of the fourth embodiment is an example of the above-mentioned mold (b). Mold 30 includes an upper die (first die) 31 and a lower mold (second mold) 32.
[0131]
　The upper die 31 has a plate-like projection 33 for forming the slit 3. The upper die 31 includes a body portion 31a, and two movable portions 31b can be moved relative to the main body portion 31a. The movable portion 31b is disposed at the bottom of the pressing surface of the main body portion 31a. Lower mold 32 includes a body portion 32a, and two movable portion 32b can be moved relative to the main body portion 32a. The movable portion 32b is disposed at the top of the pressing surface of the main body portion 32a. In the mold 30 of the fourth embodiment, both of the movable portions 32a and 32b is movable in the horizontal direction. The movable portion 31b can be moved in the vertical direction (pressing direction) integrally with the main body portion 31a. Similarly, the movable portion 32b can be moved in the vertical direction integrally with the body portion 32a.
[0132]
　Each body portion 31a and the main body portion 32a, including the pressing surface 31ap and 32ap for forming the cylindrical portion 1d and presses the outer peripheral surface of the U-shaped portion 1b. Movable portions 31b and 32b, includes a pressing surface 31bp and 32bp presses the outer peripheral surface of the U-shaped portion 1b. In one example described in the fourth embodiment, the cross-sectional circumference of the whole pressing surface is longer than the cross-sectional circumference LH tubular portion 1e. Sectional circumference of the whole pressing surface may be substantially equal to the LU sectional length of the U-shaped portion 1b.
[0133]
　For the next step (ii), will be described with reference to FIG. 5B ~ Figure 5E. Process of the fourth embodiment (ii) is a step of the example described above (B), comprising the step (ii-1) and the step (ii-2). According to step (ii), the U-shaped portion 1b, can be formed a tubular portion 1e having a slit.
[0134]
　In step (ii) of the fourth embodiment, first, as shown in FIG. 5B, placing the U-shaped portion 1b in the mold 30. Next, as shown in FIG. 5C and FIG. 5D, the end E1 and the end portion of the U-shaped portion 1b E2 (Figure 2C see) and by using the die 30 in a state of sandwiching the projecting portion 33 the U-shaped deforming the part 1b (step (ii-1)). Specifically, close both to the upper die 31 and lower die 32 are in contact, the outer peripheral surface of the U-shaped portion 1b is pressed by the pressing surface of the die 30. Step (ii-1) is the pressing surface 31bp and 32bp of the movable portion is performed in a state that does not protrude from the pressing surface 31ap and 32ap of the body portion. The step (ii-1), the tubular portion 1d is formed. In the process shown in FIG. 5C, the U-shaped portion 1c is deformed U-shaped part 1b. At this time, the two ends of the U-shaped portion 1c stops when the protrusion 33, a gap is generated between the two ends. The gap is the slit 3 of the tubular portion 1e. In the state of FIG. 5D, the end E1 and the end E2, we are opposed to each other across the protruding portion 33.
[0135]
　In the manufacturing method of the fourth embodiment, the cross-sectional circumference of the whole pressing surface of the mold 30 may be equal cross-section, length LU substantially U-shaped portion 1b. In this case, when forming the cylindrical portion 1d by greatly deform the U-shaped portion 1b, it can be suppressed compressive force is applied in the circumferential direction. Therefore, it is possible to suppress the like buckling occurs during the formation of the tubular portion 1d.
[0136]
　Next, as shown in FIG. 5E, by the end E1 and E2 of the U-shaped portion 1b is in a state sandwiching the projecting portion 33 presses the outer peripheral surface of the cylindrical portion 1d, the cylindrical portion 1d shortening the cross-sectional circumferential length LT (step (ii-2)). Specifically, the pressing surface 31bp and 32bp of the movable portion 31b and 32b, presses the outer peripheral surface of the cylindrical portion 1d by protrude from the pressing surface 31ap and 32ap of the body portion 31a and 32b. In the fourth embodiment, to press the side surface of the cylindrical portion 1d from the left and right. The cross-sectional circumference LH tubular portion 1e shorter than LU sectional length of the U-shaped part 1b by the step (ii-2) to reduce the cross-sectional circumferential length LT of the cylindrical portion 1d. In this way, the tubular portion 1e (metal molding) as shown in FIG. 5F is obtained. The butted portion 2 of the tubular portion 1e, the slits 3 are formed.
[0137]
　In the manufacturing method of the fourth embodiment, the tubular portion 1e is formed by compressing the cylindrical portion 1d in the circumferential direction. Therefore, as described in the second and third embodiments, the slit 3 can be accurately formed. In the third and the manufacturing method of the fourth embodiment, by changing the movement amount of the movable portion, it is possible to easily vary the compression ratio as described above. Therefore, even when the thickness and physical properties of the metal plate 1a is slightly changed, it may be possible to the manufacturing method of the desired tubular portion 1e without changing the mold.
[0138]
　With reference to FIGS. 15A ~ FIG 15E, a description will be given of an example of manufacturing device be used in the step (ii) of the fourth embodiment. The manufacturing apparatus includes a first support platform 151,2 one telescopic mechanism 141a, 2 one shaft 153,2 single cam unit 154. Telescopic mechanism 141a and the shaft 153 is disposed in the first support base 151. Telescopic mechanism 141a is stretchable in the pressing direction, to press the body portion 31a.
[0139]
　In step (ii) of the fourth embodiment, first, as shown in FIG. 15A, placing the U-shaped portion 1b in the mold 30. Next, as shown in FIGS. 15B and 15C, push down the first support base 151. This performs the above-described steps (ii-1), to obtain a tubular portion 1d. Next, as shown in FIG. 15D, further depressing the first support base 151 while compressing the telescopic mechanism. In this case, the two shafts 153 are two cam unit 154 is moved, the movable portion 31b and 32b are moved by the cam unit 154. Thus, as shown in FIG. 15D, the pressing surface of the movable portion 31b and 32b protrudes from the pressing surface of the body portion 31a and 32a, to press the outer peripheral surface of the cylindrical portion 1d. In this way, the step (ii-2) is performed.
[0140]
　In the apparatus shown in FIG. 15A, a mechanism for moving the first support base 151 downwardly (not shown), and the expansion mechanism 141a in a state in which no stretching is first moving mechanism of the above-described production apparatus (b) It corresponds to. Moreover, mechanisms for moving the first support base 151 downward, the shaft 153 and the cam unit 154, constitutes the second moving mechanism. These moving mechanism may be achieved by using to suit the manufacturing apparatus of the present invention the moving mechanism of a known press machine.
[0141]
　(Fifth Embodiment)
　In the fifth embodiment, explaining another example of the manufacturing method and the mold used therefor of the present invention. Manufacturing method of the fifth embodiment includes a step (i) and step (ii). Step (i) is the same as process described in the second embodiment (i), without redundant description.
[0142]
　Figure 6A, shows a mold used in the step (ii) of the fifth embodiment schematically. Mold 20 of the fifth embodiment includes an upper die (first die) 21 and a lower mold (second mold) 22.
[0143]
　Upper die 21 has a plate-like projection 23 for forming the slit 3. Each of the first upper die 21 and the second lower mold 22, comprising a pushing surface 21p and 22p for forming the cylindrical portion 1d and presses the outer peripheral surface of the U-shaped portion 1b. In the die 20 of the fifth embodiment, the cross-sectional circumference of the whole pressing surface is shorter than the LU sectional length of the U-shaped portion 1b. By deforming the U-shaped part 1b by using the die 20, the cross-sectional circumference LH tubular portion 1e can be made shorter than the LU sectional length of the U-shaped portion 1b.
[0144]
　For the next step (ii), will be described with reference to FIG. 6B ~ Figure 6E. Process of the fifth embodiment (ii) is a step of the above-described example (C). In step (ii) of the fifth embodiment, first, as shown in FIG. 6B, placing the U-shaped portion 1b in the mold 20. Next, as shown in FIGS. 6C and FIG. 6D, deforming the U-shaped portion 1b and the end E1 and the end E2 of the U-shaped part 1b by using a mold 20 so as to sandwich the protruding portion 23 by, forming a cylindrical portion 1d. Specifically, close the upper mold 21 and the lower mold 22, the outer peripheral surface of the U-shaped portion 1b is pressed by the pressing surface of the die 20. In the process shown in FIG 6C, the U-shaped portion 1c is deformed U-shaped part 1b. At this time, the two ends of the U-shaped portion 1c stops when the protrusion 23, a gap is generated between the two ends. The gap is the slit 3 of the tubular portion 1e.
[0145]
　Figure 6D is a cross-sectional circumferential length LT of the cylindrical portion 1d is, shows an example of a state which is substantially the same as the cross-sectional length LU of the U-shaped portion 1b. For sectional circumference of the pressing surface of the mold 20 is shorter than the LU sectional length of the U-shaped portion 1b, at the stage of FIG. 6D, the upper die 21 and lower die 22 do not contact. That is, in the step of FIG. 6D, the mold 20 is not yet made closed.
[0146]
　Further brought close to the upper die 21 and lower die 22 from the stage of FIG. 6D, closing the mold 20 as shown in FIG 6E. For example, moving the upper mold 21 to the bottom dead center, contacting the upper mold 21 and the lower mold 22. In this process, the two ends E1 and the end E2 is the outer peripheral surface of the cylindrical portion 1d in a state of sandwiching the projecting portion 23 is pressed by the pressing surface of the die 20. Thus, shown in FIG. 6F, the tubular portion 1e having a slit 3 in the abutting portion 2 is formed. Sectional circumference of the pressing surface of the mold 20 is shorter than the LU sectional length of the U-shaped portion 1b. Therefore, cross-sectional circumference LH tubular portion 1e becomes shorter than LU sectional length of the U-shaped portion 1b. That is, in the step of FIG. 6E, the tubular portion 1e cylindrical portion 1d is compressed in the circumferential direction.
[0147]
　In the case where sectional circumference LH tubular portion 1e before closing the mold 20 completely becomes shorter than the sectional length LU of the U-shaped portion 1b is terminated molded before closing the mold 20 completely it is also possible to. In that case, by adjusting how close to what extent the upper mold 21 and the second lower mold 22, it is possible to adjust the compression ratio of the tubular portion 1e.
[0148]
　Also in the manufacturing method of the fifth embodiment, the tubular portion 1e is formed by compressing the cylindrical portion 1d in the circumferential direction. Therefore, as described in the second embodiment, the slit 3 can be accurately formed.
[0149]
　Mold of the present invention, protrusions may be replaceable. An example protrusions of the mold exchangeable shown in FIG. Mold 20 of FIG. 7 includes an upper mold (first mold) 21 and a lower mold (second mold) 22. Upper die 21 has a portion 24 which includes a protrusion 23. Portion 24 is inserted into the hole 25 of the upper die 21, and can exchange. Protrusion 23 is a portion of two ends of the U-shaped portion (an end portion E1 and E2) are in contact, is likely to occur wear or deformation. Therefore, it is preferable that the replaceable projection 23. Furthermore, by enabling exchange protrusions 23, the above-mentioned effects can be obtained.
[0150]
　In another aspect, the present invention provides a method for producing a substantially closed cross-section parts having a gap in the abutting portion. Hereinafter, the manufacturing method of this aspect is referred to as the production method (S). Manufacturing method (S) includes a first step and second step. In the first step, a metal plate formed into U-shape, to obtain a U shaped article. The U shaped article corresponds to the molded article comprising a U-shaped portion formed in step (i) above. In the second step, using a mold, the U shaped article was formed into a substantially closed cross section, shorter than the cross-sectional circumference substantially closed section part sectional circumferential length of the U shaped article. Mold used has a protrusion corresponding to the butted portion of the substantially closed section part has an adjustable mechanism section perimeter of the substantially closed cross section parts. Examples of the mold, above the mold (a), include (b) and (c). The first step and second step, respectively, correspond to the above-described steps (i) and (ii). Substantially closed cross-section parts having a gap, mentioned above, corresponds to a metal molded article comprising a tubular portion having a slit. By "substantially closed cross-section part" means a part having a substantially closed cross section. By "substantially closed cross-section" refers to cross a gap exists between the two ends which is abutted with the metal plate that is formed into a tubular shape. Substantially closed section part may have a gap over the entire length of the butted portion may have gaps in a part of the butt portion.
[0151]
　In the production method (S), cross-sectional circumference of the mold may be shorter than the cross-sectional circumferential length of the U shaped article. Here, the "cross-sectional circumference of the mold" refers to a cross-sectional circumference of the mold when fully closing the mold. The cross-sectional circumference of the mold when fully closing the mold by shortening than the cross-section perimeter of the U shaped article, the cross-sectional circumference substantially closed section parts can be made shorter than the cross-sectional circumference of the U shaped article . A mold having this configuration corresponds to the above-mentioned mold (a) and (c).
[0152]
　In the production method (S), and a upper and lower molds where the mold has said protruding portion, at least one of the upper mold and the lower mold may have a main body portion and a movable portion good. A mold having this configuration corresponds to the above-mentioned mold (b).
[0153]
　In another aspect, the present invention is to mold the U shaped article in a substantially closed cross section, to provide a mold for producing a substantially closed cross-section parts having a gap in the abutting portion. In the following, the mold is referred to as a mold (T1). Mold (T1) has an upper die having a protrusion corresponding to the butt portion of the substantially closed section part, and a lower mold. Mold (T1) has an adjustable mechanism section perimeter of the substantially closed cross section parts. Then, at least one of the upper mold and the lower mold is divided into a plurality. Mold (T1) corresponds to the above-mentioned mold (a). In the mold (T1), the protrusion of the upper die may be divided. An example of a mold having this configuration, a mold 20 shown in Figure 3A.
[0154]
　In another aspect, the present invention is to mold the U shaped article in a substantially closed section provides another mold for manufacturing a substantially closed cross-section parts having a gap in the abutting portion. In the following, it referred to as the die mold and (T2). Mold (T2) has an upper die having a protrusion corresponding to the butt portion of the substantially closed section part, and a lower mold. Mold (T2) has an adjustable mechanism section perimeter of the substantially closed cross section parts. Then, at least one of the upper die and the lower die has a body portion and a movable portion. Mold (T2) corresponds to the above-mentioned mold (b).
[0155]
　In the mold (T1) and (T2), the protrusion may be replaceable.
Example
[0156]
　Hereinafter, the present invention will be specifically described by examples.
[0157]
　[Example 1]
　In Example 1, to form a U shaped article (U-shaped part) by the manufacturing method shown in FIGS. 2A ~ 2B, the manufacturing method shown further in FIG. 3B ~ 3E, tubular member having a slit (metal molding) was prepared. A metal plate (blank) is, TS (tensile strength) at 590 MPa, the plate thickness using the hot rolled steel sheet 2.3 mm. The outer diameter of the tubular member is 50 mm, the length was 200 mm. The width of the upper mold of the protrusions was set to 5 mm.
[0158]
　[Example 2]
　In Example 2, using the same metal plate as that in Example 1, the manufacturing method shown in FIGS. 2A ~ 2B and FIGS. 4B ~ 4E, to prepare a tubular member having a slit. The width of the protrusion dimensions and the upper mold of the tubular member were the same as in Example 1.
[0159]
　[Example 3]
　In Example 3, using the same metal plate as that in Example 1, to form a U shaped article (U-shaped part) by the manufacturing method shown in FIGS. 2A ~ 2B, further FIG 5B ~ 5E by the manufacturing method shown in, to produce a tubular member having a slit. The width of the protrusion dimensions and the upper mold of the tubular member were the same as in Example 1.
[0160]
　[Example 4]
　In Example 4, using the same metal plate as that in Example 1, to form a U shaped article (U-shaped part) by the manufacturing method shown in FIGS. 2A ~ 2B, further FIG 6B ~ 6E by the manufacturing method shown in, to produce a tubular member having a slit. The width of the protrusion dimensions and the upper mold of the tubular member were the same as in Example 1.
[0161]
　[Comparative Example 1]
　In Comparative Example 1, using the same metal plate as that in Example 1 was subjected to U formed by the method shown in FIGS. 2A ~ 2B. Thereafter, as shown in FIGS. 10A ~ 10B, by performing O molding using a mold having no projection portion (the upper die 51 and lower die 52) to produce a tubular member 50a. Sectional circumference of the pressing surface of the mold when fully closing the mold were the same as section length of the U shaped article (U-shaped portion).
[0162]
　[Comparative Example 2]
　using the same metal plate as that in Example 1 was subjected to U formed by the method shown in FIGS. 2A ~ 2B. Thereafter, as shown in FIGS. 11A ~ 11B, it was O molding using a mold having no projection part (upper die 51 and lower die 52) and the core 53. Thus, to produce a tubular member 50b having a slit. Sectional circumference of the pressing surface of the mold when fully closed the mold, was longer than the cross-sectional length of the U shaped article (U-shaped portion).
[0163]
　The compression ratio C of Example 1-4 was 0.99%. Compressibility C of Comparative Examples 1 and 2 was about 0%.
[0164]
　Evaluation
　Example 1, the tubular member of Comparative Example 1, and Comparative Example 2 were measured strain distribution in the thickness direction in the cross section. The measurement results are shown in Figure 12A. The vertical axis of FIG. 12A shows the absolute value of the distortion. As shown in FIG. 12A, a tubular member of the first embodiment, the absolute value of the distortion compared to the tubular member of Comparative Example 1 and 2 is large, the strain distribution in the thickness direction was small. The result is a tubular member of Example 1, suggesting that is applied almost uniformly compressive stress across the thickness direction.
[0165]
　Furthermore, the tubular member of Examples 2-4, and Comparative Example 2 were measured strain distribution in the circumferential direction in the cross section. The measurement results are shown in Figure 12B. The vertical axis of FIG. 12B shows the absolute value of the distortion. In FIG. 12B, the bottom of the cross-section of the tubular member and 0 °, the butt portion was 180 °. As shown in FIG. 12B, the tubular member of Examples 2-4, the absolute value of the distortion is larger than the tubular member of Comparative Example 2. The result is a tubular member of Examples 2-4, a large compressive stress around the whole circumference suggesting that has occurred.
[0166]
　As shown in FIGS. 12A and 12B, according to the manufacturing method of Examples 1-4, it is possible to make the compressive stress applied in the thickness direction and the circumferential direction of the tubular member to more evenly. Therefore, according to the manufacturing method of Examples 1-4, it can be suppressed springback, it is possible that the shape accuracy to produce high metal formed article.
[0167]
　The tubular member of Example 1, Comparative Example 1 and 2, the distribution of Vickers hardness was determined by using the result of the simulation by FEM (Finite Element Method). From the distribution to determine the variation S of the Vickers hardness in the plate thickness direction of the first position described above. Similarly, the second and third positions to determine the variation S of the Vickers hardness in the sheet thickness direction. As a result, the tubular member of the first embodiment, first, in the second, and the third one of the positions of, variation S was about 0.1. That is, in the tubular member of the first embodiment, the circumferential direction of the mean value of the variation S was about 0.1. The result is a tubular member of Example 1, the variation of Vickers hardness suggesting that less in any of the plate thickness direction and the circumferential direction. On the other hand, in Comparative Examples 1 and 2, first, in the second, and the third one of the positions of, variation S was about 0.7. That is, in the tubular member of Comparative Example 1 and 2, the circumferential direction of the mean value of the variation S was about 0.7.
[0168]
　The average value of the circumferential direction of the above-described variation S, the graph showing the relationship between the reduction rate of the uniaxial compressive strength, shown in Figure 13. Graph of FIG. 13 is a graph average value of the circumferential variation S is assumed plurality of round tube to be a predetermined value, it was obtained by simulating the results when subjected to uniaxial compression tests for their round tube it is. The vertical axis of the graph of FIG. 13 is a rate of decrease of the uniaxial compressive strength when the average value of the circumferential variation S is relative to the round tube is zero. Specifically, to simulate a uniaxial compression test for the round tube, the reduction rate of the uniaxial compressive strength of the other round tube uniaxial compressive strength as a measure of the time the result of obtaining (%), the graph of FIG. 13 It is shown in the vertical axis of.
[0169]
　For reference, in FIG. 13 shows two dotted lines represent the trend of change of the rate of decrease of the uniaxial compressive strength. As shown in FIG. 13, when the average value of the circumferential variation S is 0.4 or more, the reduction rate of the uniaxial compressive strength increased significantly. On the other hand, if the average value of the circumferential variation S is less than 0.4, the reduction rate of the uniaxial compressive strength was small. Results in Figure 13, the circumferential direction of the mean value of the variation S be less than 0.4 suggesting the importance.
[0170]
　In no conventional O molding compressing the metal plate in the circumferential direction (O molding of Comparative Example 1 and 2), it is difficult to spring back is large, to form good slit accuracy. On the other hand, according to the production method of the present invention can be formed with high accuracy the distance between the slits. Further, since the conventional O molding is a simple bending, less work hardening thickness center, the fatigue strength of the molded article obtained is low. In contrast, according to the production method of the present invention, a high fatigue strength metal formed article can be obtained. Further, in the conventional method for manufacturing a tubular member having a slit, or a tubular from bending a metal plate little by little, or to the tubular after adding the aperture to the metal plate had if necessary. Compared to such a conventional manufacturing method, according to the present invention, it is possible to reduce the number of steps, as a result, cost reduction can be realized.
Industrial Applicability
[0171]
　The present invention can be used a metal molded article comprising a tubular portion having a slit, and its manufacturing method. Furthermore, the present invention provides a manufacturing apparatus for manufacturing the shaped article, and can be used in a mold for use therein.
DESCRIPTION OF SYMBOLS
[0172]
　1 metal formed article
　1a metal plate
　1b, 1c U-shaped portion
　1d cylindrical portion
　1e tubular section
　2 abutting portion
　3 slits
　(clearances) 11 die
　12 punch
　20 and 30 the mold
　21, 31 the upper die
　21a first upper die
　21b the second upper die
　22 and 32 the lower mold
　22a first lower mold
　22b second lower mold
　23, 33 protrusion
　23a first projection
　23b second protrusions
　31a, 32a main body portion
　31b, 32 b movable portion
　E1 , E2 end

The scope of the claims
[Claim 1]
　A method of manufacturing a metal molded article comprising a tubular portion having a slit,
　by deforming the (i) a metal plate, a step of cross-section to form a U-shaped portion is U-shaped,
　(ii) by deforming the U-shaped portion of two ends of the U-shaped portion by using the mold having the protruding portion so as to sandwich the protruding portion, and forming the tubular portion having the slit hints,
　in the process of the (ii), is shorter than the sectional length LU of the cross-sectional circumferential length LH of the tubular portion and the U-shaped section, method for producing a metal shaped article.
[Claim 2]
　Wherein said cross-sectional length LU of the U-shaped portion and the cross-sectional circumferential length LH of the tubular
　portion, satisfy 0.2 ≦ 100 × (LU-LH ) / LU <1 expression, according to claim 1 Production method.
[Claim 3]
　The step of (ii) is
　by deforming the U-shaped portion with the mold so as to sandwich the (ii-1) the said two ends the protrusion of the U-shaped portion, said forming a tubular portion comprising a tubular portion,
　by pressing the outer peripheral surface of the cylindrical portion in (ii-2) a state where the two ends across the protruding portion, of the cylindrical portion and a step of shortening the cross-sectional circumferential length LT, the process according to claim 1 or 2.
[Claim 4]
　The mold comprises a first mold having the protruding portion, and a second die,
　wherein each first and second die, the tubular by deforming the U-shaped portion includes first and second pressing surface for forming a part,
　at least one mold selected from the first mold and the second mold is separable into a plurality of die members,
　wherein in (ii-1) step, to form the tubular portion by deforming the U-shaped portion by using the mold in which a plurality of mold members are separated,
　the (ii in step -2), presses the outer peripheral surface of the tubular portion by approaching the plurality of die member, thereby shortening the cross-sectional circumferential length LT of the cylindrical portion, according to claim 3 the method of production.
[Claim 5]
　The mold includes a pressing surface which corresponds to the outer peripheral surface of the tubular portion,
　the cross-sectional circumference of the pressing surface is less than the cross-sectional length LU of the U-shaped section, one of the claims 1 to 4, 1 the process according to claim.
[Claim 6]
　The mold comprises a first mold having the protruding portion, and a second die,
　wherein each first and second die, the tubular by deforming the U-shaped portion includes first and second pressing surface for forming a part,
　at least one mold selected from the first mold and the second mold includes a body portion, relative to the body portion and a relatively moving a movable unit,
　in the process of the (ii-1), wherein using the mold pressing surface of the movable portion is in a state not projecting from the pressing surface of the main body portion U forming said tubular portion by deforming the shaped part,
　in the process of the (ii-2), the tubular portion by projecting the said pressing surface of said movable portion from said pressing surface of said main body portion pressing the outer peripheral surface of, thereby shortening the cross-sectional circumferential length LT of the tubular portion, claim The method according to 3.
[Claim 7]
　A metal molded article comprising a tubular portion having a slit,
　a variation S of the plate thickness direction of the Vickers hardness in the cross section of the tubular portion when expressed by the following formula, the average value of the circumferential variation S 0 less than .4, metal moldings.
　S = (Bmax-Bmin) / Bmax
, where, Bmin is the minimum value of the thickness direction of the Vickers hardness in the cross-section. Bmax is the maximum value of the thickness direction of the Vickers hardness in the cross-section.
[8.]
　A manufacturing apparatus for manufacturing a metal molded article comprising a tubular portion having a slit,
　comprising: a mold, and a moving mechanism for moving the mold,
　the mold is for forming the slit a first mold including a protrusion, and a second die,
　wherein each first and second die, said cross section to deform the U-shaped portion is U-shaped slit includes first and second pressing surfaces for forming the cylindrical portion having a gap which becomes,
　the mold, the outer peripheral surface of the cylindrical portion of the cross section perimeter is the cylindrical portion to be shorter having a configuration for pressing, the manufacturing apparatus.
[Claim 9]
　The first mold and at least one mold selected from the second mold is separable into a plurality of die member,
　the moving mechanism, the state in which the plurality of die member are separated a first moving mechanism for approximating the second die and the first die,
　and a second moving mechanism for approximating said plurality of die member which separates, according to claim 8 of manufacturing equipment.
[Claim 10]
　The first mold and at least one mold selected from the second mold includes a body portion and a relatively movable movable portion relative to the body portion,
　the moving mechanism,
　a first moving mechanism for the movable portion to approach the second die and the first die in a state that does not protrude from the first and second pressing surface,
　so as to protrude from the pressing surface wherein and a second moving mechanism for moving the movable portion, the manufacturing apparatus according to claim 8.
[Claim 11]
　A mold for manufacturing a metal molded article comprising a tubular portion having a slit,
　comprising a first mold including a protrusion for forming the slits, and a second mold,
　the second each of the first and second mold includes first and second pressing surfaces for forming the cylindrical portion having a gap section is the slit to deform the U-shaped portion is U-shaped ,
　having the structure for pressing the outer peripheral surface of the cylindrical portion so that the cross section circumference of the cylindrical portion is short, the mold.
[Claim 12]
　The first mold and at least one mold selected from the second mold is separable into a plurality of die member die according to claim 11.
[Claim 13]
　Wherein the first mold is separable into a first mold member and a second mold member,
　said protrusion, said first protrusion included in the first mold member first is constituted by the second protruding portions included in the second mold member, the mold according to claim 12.
[Claim 14]
　The first mold and at least one mold selected from the second mold includes a body portion and a relatively movable movable portion relative to the body portion, according to claim 11 mold.
[Claim 15]
　The protrusions is exchangeable mold according to any one of claims 11 to 14.