0001]The invention, of the press-molded product a manufacturing method and a manufacturing line. More particularly, to a manufacturing method and a manufacturing line of the press-molded product for use in an automobile.
BACKGROUND
[0002]Automobile frame parts (e.g., pillar) or the like is obtained a metal plate such as a steel plate by press molding. Frame parts of automobiles has a groove-shaped or hat-shaped cross-sectional shape for ensuring the strength. The frame components of an automobile may have a stepped portion in the top plate. Due to which such attachment of other components. Blank, when pressed into a part having a step portion in the top plate, may wrinkle is generated in the molded part. To suppress the occurrence of wrinkles, parts having a step portion in the top plate may be formed by drawing. Means an inclined region connecting the different regions of the height between the step portion, the angle of inclination is not limited to 90 °.
[0003]
　In recent years, the automobile, in order to improve the contributing fuel to the prevention of global warming, weight reduction of the vehicle body is required. In addition, the improvement of safety at the time of collision accident is required. These requirements, as a material of the frame parts and the like, tensile strength is high metal plate used.
[0004]
　However, it is likely to occur cracks when molded diaphragm a metal plate of high strength. Ductile metal plates of high strength is because low.
[0005]
　Method of suppressing production of wrinkles of the press-molded product is disclosed in JP 2014-240078 (Patent Document 1). Inhibiting the production method of the wrinkles and cracking of the press-molded product is disclosed in WO 2011/145679 (Patent Document 2).
[0006]
　Patent Document 1 discloses a method to suppress the occurrence of wrinkles is produced by draw-forming a press molded article is bent in an L-shape. In the manufacturing method of Patent Document 1, for press-forming while restraining the regions bent in L-shape pad. Thus, in a region that is bent in an L-shape, the occurrence of wrinkles can be suppressed, and is described in Patent Document 1.
[0007]
　Patent Document 2 discloses a method of manufacturing the bending of the press-formed product which is bent in an L-shape or T-shape. In the manufacturing method of Patent Document 2, while restraining a portion of the top plate portion of the press-molded product in the pad, forming a bent region of the press-molded product. Thus, in a region that is bent in an L-shape or T-shape, the occurrence of wrinkles can be suppressed, and are described in the patent document 2.
CITATION
Patent Document
[0008]
Patent Document 1: JP 2014-240078 Patent Publication
Patent Document 2: WO 2011/145679
Summary of the Invention
Problems that the Invention is to Solve
[0009]
　However, the production method disclosed in Patent Documents 1 and 2 is directed to a production of a press molded article is bent in an L-shape or the like. Therefore, Patent Documents 1 and 2, there is no disclosure of the production of the press-molded product having a step portion in the top plate.
[0010]
　An object of the present invention, even when producing a press-molded product having a step portion in the top plate using a metal plate of high strength and providing wrinkle, a manufacturing method and a manufacturing line cracking can be suppressed is there.
Means for Solving the Problems
[0011]
　Press-molded product produced by the production method of the embodiment of the present invention includes a top plate portion, and a vertical wall portion. Top plate portion has a stepped portion in the longitudinal direction. It stepped portion, extending from the end portion in the width direction, across at least a portion of the width direction. Vertical wall portion, adjacent to the top plate portion via a ridge portion on the end portion in the width direction there is a step portion of the top plate portion.
[0012]
　Method for manufacturing a press molded product of the present embodiment includes a first pressing step, a second press step. In the first press step, by using a first mold, molding the intermediate molded article from the workpiece. Intermediate molded article, and the step portion of the top plate portion, and a provisional vertical wall portion which at least part of the shape of the vertical wall portion adjacent the top plate is molded through the ridge portion, the ridge line portion of the provisional vertical wall portion having a provisional flange portion adjacent to the provisional vertical wall portion via the provisional ridge portion located on the end opposite the. In a second press step using the second die to obtain a press-molded product from the intermediate product. In a second press step, carrying out the molding of moving towards the provisional flange provisional ridge while restraining at least a portion of the top plate portion of the intermediate molded article.
[0013]
　Production line of the present embodiment includes a first pressing machine, and a second press located downstream of the first pressing machine, a. The first press machine includes a first punch, a first die, the first pad. The first punch has a first distal portion, the first punch wall, and a punch flat portion. The first end extends from the end portion in the width direction and has a stepped portion in the longitudinal direction across at least a portion of the width direction. The first punch wall, adjacent to the first end through the first punch shoulder at the end there is a step portion of the first distal portion. Punching the flat portion is adjacent to the first punch wall portion through the first punch wall and the punch bottom shoulder. The first die has first punch shoulder of the first punch, opposite the first punch walls and the punch flat portion. The first pad is opposed to the first end of the first punch. The second press includes a second punch, the second die, the second pad. The second punch includes a second distal portion, the second punch walls. The second tip is the same shape as the first tip. The second punch wall, adjacent to the second distal end portion through the second punch shoulder at the end of the step portion of the second distal portion is. The second die, facing the second punch shoulder of the second punch, and the second punch walls. The second pad is opposed to the second distal end of the second punch. Height of the second punching wall portion of the second press is greater than the height of the first punch wall portion of the first pressing machine. Note that the "height" in the present invention means the height direction of the size unless stated positional relationship.
Effect of the invention
[0014]
　According to the production method of the present invention, even when producing a press-molded product having a step portion in the top plate using a metal plate of high strength, wrinkles and cracks can be suppressed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015]
[1] Figure 1 is a perspective view of the press-molded product produced by the production method of this embodiment.
FIG. 2 is a diagram illustrating the size of wrinkles in the case of bending a press-molded product as shown in Figure 1 in a single step, the relationship between the shape of the step portion.
FIG. 3 is a diagram showing a press molding shape of the workpiece in the press forming early case in one step.
[4] FIG. 4 is a view showing the shape of the workpiece in the press forming metaphase in the case of press molding in one step.
FIG. 5 is a diagram showing a press molding workpiece shape at the time of press forming completes when in one step.
FIG. 6 is a stress acting on the micro-elements in the vertical wall just below the step portion (inclined portion) is a diagram schematically showing.
[7] FIG. 7 is a view showing the shape of the workpiece after the first step first completed in the case of press molding in two steps.
[8] FIG. 8 is a view showing the shape of the workpiece during press forming of the two steps first in the case of press molding in two steps.
[9] FIG. 9 is a view showing the shape of the workpiece during the second step first completed in the case of press molding in two steps.
[10] FIG 10 is a diagram showing the magnitude of shear strain associated with the progress of the press forming.
[11] FIG 11 is a perspective view of an intermediate molded article obtained by the first pressing step.
[12] FIG 12 is a diagram showing a state before starting forming of the first pressing step.
[13] FIG 13 is a diagram showing a molding initial state of the first pressing step.
[14] FIG 14 is a diagram showing a state during molding completion of the first pressing step.
[15] FIG. 15 is a sectional view showing a first mold when carrying out the draw forming in a first pressing step.
[16] FIG 16 is a diagram showing a state before the start molding of the second pressing step.
[17] FIG 17 is a diagram showing a molding initial state of the second pressing step.
[18] FIG 18 is a diagram showing a state upon completion of the forming in the second pressing step.
[19] FIG 19 is a perspective view showing an intermediate product of the present invention embodiment.
[20] FIG 20 is a graph showing the results of the present invention and comparative examples.
[21] FIG 21 is a perspective view showing an example of the press-molded product of the present embodiment.
[22] FIG 22 is a perspective view showing an example of the press-molded product of the present embodiment.
[23] FIG 23 is a diagram showing a production line of the present embodiment.
DESCRIPTION OF THE INVENTION
[0016]
　Press-molded product produced by the production method of this embodiment includes a top plate portion, and a vertical wall portion. Top plate portion has a stepped portion in the longitudinal direction. It stepped portion, extending from the end portion in the width direction, across at least a portion of the width direction. Vertical wall portion, adjacent to the top plate portion via a ridge portion on the end portion in the width direction there is a step portion of the top plate portion.
[0017]
　Method for manufacturing a press molded product of the present embodiment includes a first pressing step, a second press step. In the first press step, by using a first mold, molding the intermediate molded article from the workpiece. Intermediate molded article, and the step portion of the top plate portion, and a provisional vertical wall portion which at least part of the shape of the vertical wall portion adjacent the top plate is molded through the ridge portion, the ridge line portion of the provisional vertical wall portion having a provisional flange portion adjacent to the provisional vertical wall portion via the provisional ridge portion located on the end opposite the. In a second press step using the second die to obtain a press-molded product from the intermediate product. In a second press step, carrying out the molding of moving towards the provisional flange provisional ridge while restraining at least a portion of the top plate portion of the intermediate molded article.
[0018]
　In the production method of the present embodiment, press molding the workpiece in two different steps. In one step th intermediate molded article is obtained which is molded to a part of the height of the press-molded product (Completed). Intermediate product is provided with a provisional flange portion. To mold the provisional flange portion to the intermediate molded article, to restrain the region corresponding to the provisional flange portion of the workpiece in the mold. As a result, the flow of material with the progress of the press molding can be suppressed in the provisional flange. Therefore, the intermediate molded article, compared with one pressing step only press molded article molded by the shear strain causes wrinkles is suppressed. From intermediate product obtained in the first step first, when forming the remaining part in two steps first, as compared with the case of forming only one pressing step, shear distortion of the press-molded product (Completed) is suppressed that. This is because shear strain occurring in the intermediate molded article is small. Thus, wrinkles are less likely to occur in the press-molded product.
[0019]
　The height of the provisional vertical wall adjacent to the top plate portion of the lower stepped portion of the intermediate product (step lower) is preferably not more than 50% of the height of the vertical wall portion of the press-molded product. As described above, shear strain increases with the progress of the press forming. Therefore, a forming height of 1 step eyes if lower than the forming height of the second step first, can effectively reduce the shear strain of the intermediate molded article obtained in the first step first. More preferably, in the first pressing step, the entire region of the ridge line portion of the press-molded product is molded.
[0020]
　Tensile strength is low workpiece is likely to plastically deform. It is an area wrinkles when press-molding by a high tensile strength workpiece mold, the tensile strength is press-molding the lower workpiece tensile strength is low workpiece is plastically deformed mold order to adapt to, wrinkle is unlikely to occur. In the press molding of the tensile strength is low workpiece wrinkle is often particularly no problem. On the other hand, high tensile strength workpiece is wrinkle is likely to occur since it is difficult to plastically deform. Therefore, the manufacturing method of the present embodiment is particularly effective when forming a workpiece of high strength. Specifically, in the above manufacturing method, the tensile strength of the workpiece is preferably at least 590 MPa. The tensile strength of the workpiece is more preferably not less than 980 MPa.
[0021]
　The greater the height of the step portion of the press-molded product, large wrinkles. In the above manufacturing method, the height H of the step portion of the press-molded product, even prone conditions wrinkles satisfying the formula (1) below with respect to the radius of curvature R of the ridge line portion of the press-molded product, it is possible to wrinkle molding without.
　H ≧ 0.4R (1)
[0022]
　Production line of the present embodiment includes a first pressing machine, and a second press located downstream of the first pressing machine, a.
[0023]
　The first press has a structure of the following (1) or (2).
[0024]
　(1) The first press machine includes a first punch, a first die, the first pad. The first punch has a first distal portion, the first punch wall, and a punch flat portion. The first end extends from the end portion in the width direction and has a stepped portion in the longitudinal direction across at least a portion of the width direction. The first punch wall, adjacent to the first end through the first punch shoulder at the end there is a step portion of the first distal portion. Punching the flat portion is adjacent to the first punch wall portion through the first punch wall and the punch bottom shoulder. The first die has first punch shoulder of the first punch, opposite the first punch walls and the punch flat portion. The first pad is opposed to the first end of the first punch. The first pad has a shape obtained by inverting the uneven shape of the first end. Note that the subsequent "facing" refers to as described above, the shape of the mold in addition to the positional relationship of the mold is inverted. That is, if the shape convex one mold, the shape of the other mold which faces are concave.
[0025]
　(2) the first pressing machine includes a first punch, blank holder, the first die. The first punch has a first distal portion, and a first punch wall. The first end extends from the end portion in the width direction and has a stepped portion in the longitudinal direction across at least a portion of the width direction. The first punch wall, adjacent to the first end through the first punch shoulder at the end there is a step portion of the first distal portion. Blank holder is adjacent to the first punch. The first die is opposite to the first punch and blank holder.
[0026]
　The second press includes a second punch, the second die, the second pad. The second punch includes a second distal portion, the second punch walls. The second tip is the same shape as the first tip. The second punch wall, adjacent to the second distal end portion through the second punch shoulder at the end of the step portion of the second distal portion is. The second die, facing the second punch shoulder of the second punch, and the second punch walls. The second pad is opposed to the second distal end of the second punch. Height of the second punching wall portion of the second press is greater than the height of the first punch wall portion of the first pressing machine.
[0027]
　[Press-molded article]
　FIG. 1 is a perspective view of the press-molded product produced by the production method of this embodiment. For illustration, on the fan to the top plate 2, and lower the fan to the flange portion 6. Press-molded product 1 includes a top plate portion 2, and a vertical wall portion 3. Top plate 2 has a longitudinal direction in the stepped portion 4, the stepped upper portion of the top plate 2a and the step bottom of the top plate 2c. Top plate 2a of the step upper leads a stepped portion 4. Stepped portion 4 leads the step bottom of the top plate portion 2c. Stepped portion 4 extends from the width direction of the end portion 2d of the top plate 2. In Figure 1, it shows a case where the step portion 4 exists over the entire width of the press-molded product 1. However, the stepped portion 4 may not be present in the entire region in the width direction of the press-molded product 1. Stepped portion 4 may Yokogire a portion of the width direction of at least press-molded article 1 (for example, FIG. 22). The end 2d of the top plate 2 there is a ridge portion 5. Contour of the ridge 5 is R configuration. In the following case will be described workpiece is a metal plate.
[0028]
　Vertical wall portion 3, adjacent to the top plate portion 2 via the ridge portion 5. Vertical wall portion 3 includes vertical wall 3a immediately below the stepped upper, the vertical wall portion 3b and the vertical wall portion 3c of the right under the stepped bottom just below the step portion. Vertical wall portion 3a immediately under the stepped top, adjacent to the top plate portion 2a of the step upper through the ridge 5. Vertical wall portion 3b immediately below the stepped portion, adjacent to the stepped portion 4 of the top plate portion 2 via the ridge portion 5. Vertical wall portion 3c of the right under the stepped bottom, adjacent to the top plate portion 2c of the step bottom through the ridge 5.
[0029]
　In Figure 1, it shows a case where the cross-sectional shape perpendicular to the longitudinal direction of the press-molded product 1 is hat-shaped. Thus, the press-molded product 1 is provided with a flange portion 6. However, the sectional shape of the press-molded article 1 may not be hat-shaped. Specifically, and piece hat shape with only one flange portion 6, the flange portion 6 may have a groove shape becomes all during molding vertical wall. Further, the press-molded product 1 may not be a hat-type or the like, may be of a half shape of the shape (see FIG. 21). The step portion 4 may not be across the top plate 2 (see FIG. 22). Further, may be the one stepped portion 4 of the press-molded product 1, 3, may be four there, the number of the stepped portion may be any number.
[0030]
　As shown in FIG. 1, wrinkles occur vertical wall portion 3b and the vertical wall portion 3c of the right under the stepped bottom just below one if only bending molding step the step portion of the press-molded article having a stepped portion 4 to the top plate 2 It's easy to do. It will be described later wrinkle mechanism of occurrence of. Further, generation of wrinkles of the press-molded product is related to the radius of curvature R of the height H and the press molded article ridge portion of the cross section of the stepped portion of the top plate. The greater the height H of the step portion of the top plate, large wrinkles. Smaller radius of curvature R of the cross section of the ridge portion, large wrinkles.
[0031]
　The present inventors, the relationship between the size of the radius of curvature R and wrinkles of the ridge line portion of the height H and the press molded product of the step portion of the top plate of the press-molded product was investigated by simulation.
[0032]
　Figure 2 is a diagram illustrating the size of the wrinkles in the case of bending a press-molded product as shown in Figure 1 only in one step. The vertical axis of FIG. 2 shows the difference △ 1 / [rho maximum value and the minimum value of the principal curvatures. 2, the horizontal axis represents the ratio H / R of the curvature radius R of the ridge line portion of the step portion of the top plate of the press-molded product height H and the press molded product. In the simulation shown in FIG. 2, it was variously changed the ratio H / R of the curvature radius R of the height H and the edge line portion of the press-molded product of the step portion of the top plate of the press-molded product as shown in Figure 1. Further, in the simulation shown in FIG. 2, as a workpiece, using JAC270DC and JSC980Y defined by the Japan Iron and Steel Federation Standards. Square marks in Fig. 2 shows the results of the JAC270DC, rhombic marks represent the results of JSC980Y.
[0033]
　In the simulation shown in FIG. 2, it was investigated principal curvatures 1 / [rho at any point of the vertical wall portion 3c of the right under the bottom step of the press-molded product. To calculate the difference △ 1 / ρ between the maximum value and the minimum value of the main curvature 1 / ρ, it was used as an index of evaluation of wrinkles. △ about 1 / ρ is large, indicating that the generated wrinkle is large. As shown in FIG. 2, the value of the ratio H / R is less than 0.4 △ 1 / ρ was not significant change. However, if the ratio H / R is 0.4 or more, △ 1 / value of ρ is increased and the wrinkle generation is, the ratio H / R is compared with the case of less than 0.4, was particularly noticeable. The main curvatures were calculated by the same method as in Example to be described later.
[0034]
　As described above, in order to suppress wrinkles generated in the vertical wall portion 3c of the right under the vertical wall portion 3b and the step bottom immediately below the stepped portion of the press-molded product drawing is suitable. However, since the easily cracked when draw forming a metal plate of high strength, it is not possible to mold the press-formed product shape as an object of the present invention only one drawing. Accordingly, the present inventors have also by press-forming by bending a metal plate of high strength, a manufacturing method capable of suppressing wrinkles generated in the vertical wall portion 3b and the vertical wall portion 3c of the right under the stepped bottom just below the step portion investigated.
[0035]
　The present inventors have found that the press-molded product having a step portion in the top plate (hereinafter, simply referred to as "press-molded product".) Was investigated size of wrinkles when molded in only one bending . Specifically, we investigated the shape of the workpiece in the press forming by simulation by FEM (Finite Element Method).
[0036]
　3 to 5 are diagrams showing a simulation result when molding a press molded article shown in FIG. 1 by bending by one step. FIGS. 3-4 shows the shape of the workpiece during press forming. Figure 3 shows a press-molding an early stage. Figure 4 shows a medium-term press molding. Figure 5 shows the steps in press molding is complete. In Figure 3-5, for ease of understanding, wherein a cross-sectional view of a mold in each stage.
[0037]
　3 and 4, more than meat occurs and constrained by the upper and lower molds to define a loose as region X. The region X is a region serving as a vertical wall portion 3c of the right under the vertical wall portion 3b and the step bottom just below the step portion at the molding bottom dead center (see FIG. 5). On the other hand, the vertical wall portion 3a immediately below the stepped upper does not correspond to the region X for more than meat has not occurred. Also, does not correspond to the region X for no flange portion is also too meat is a plate end. Wrinkles occur when a large meat more than in the region X. In particular, the vertical wall portion 3b immediately below the stepped portion is deformed to absorb the meat more than (shear deformation) wrinkles order is generated occurs at the time of molding tends.
[0038]
　6, the stress state acting on the vertical wall portion immediately below the stepped portion of the press-molded product of the present embodiment is a view schematically showing. During molding of the press-molded product, the microelements A of the vertical wall portion 3b immediately below the stepped portion, in order to absorb more than meat produced in the region X, the shear stress T12 acting in-plane direction of the workpiece. The shear stress T12 is decomposed and the compressive stress S1 and tensile stress S2 represents the main stress. When such stress is loaded, microelement A square is deformed into a parallelogram. In other words, microelement A is sheared. Therefore, the shear strain generated in the microelements A. The shear strain is one of the causes to deteriorate the wrinkles of the press-molded product.
[0039]
　The degree of wrinkles caused by too meat when press forming the hat shape of the press-molded product having a step portion, which depends on the width of the top plate portion. If the width of the top plate portion of the step lower W2 (see FIG. 1) is less than 3 times the radius of curvature R of the ridge line portion of (W2 ≦ 3R), wrinkles the width direction of the tensile stress of the press-molded product is effectively act less likely to occur. On the other hand, when the width W2 of the top plate portion is larger than 3 times the radius of curvature R of the ridge line portion of (W2> 3R), wrinkles are likely to occur. The radius of curvature R, in the ridge portion in the width direction end portion of the step portion, means the radius of curvature thickness center in the cross section perpendicular to the longitudinal direction.
[0040]
　The degree of wrinkles caused by too meat when press forming the hat shape of the press-molded product having a stepped portion is also dependent on the thickness of the workpiece. Thickness of the workpiece is because governing the flexural rigidity of the workpiece. As the plate thickness is thin wrinkle is likely to occur.
[0041]
　Furthermore, the extent of wrinkles caused by too meat when press forming the hat shape of the press-molded product having a stepped portion is also dependent on the yield strength of the workpiece. Meat-odd during press molding is because caused by out-of-plane deformation under elastic deformation. Wrinkles as the yield strength of the workpiece is high likely to occur.
[0042]
　The present inventors have decreased the shear distortion of the vertical wall portion 3b immediately below meat odd and the step portion of the region X that occurs during molding of the press-molded product 1, the vertical wall portion 3b immediately below the stepped portion of the press-molded product 1 and wrinkles generated in the vertical wall portion 3c of the right under the stepped lower studied a method of inhibiting, to give the following findings.
[0043]
　In order to suppress the occurrence of wrinkles, when forming the ridge portion at the end of the step portion is formed by out-of-plane deformation, it is essential to reduce as much as possible the elastic out-of-plane deformation. In other words, actively plastically deforming the ridge portion, it may be reduced as much as possible out-of-plane deformation that increases with the progress of the press molding.
[0044]
　Accordingly, the present inventors have found that separate the press-molding step of press-molded article 1 into a plurality. The present inventors have found that in the first pressing step, and the step portion of the press-molded product, and the ridge portion of the portion adjacent to the step portion, adjacent to the top plate portion via the ridge portion was vertical wall portion of the part a region adjacent to the stepped portion through the ridge portion of the provisional vertical wall shape is formed, it was found to be molded. Forming of the step portion, it is desirable to mold the entire region of the step portion along a ridge line portion, it is not necessary to mold the entire region of the step portions along the ridge line portion. Inhibiting effect of the wrinkles generated by molding the part of the area of ​​the step portion is. The present inventors have found that after the first pressing step has been found that forming the remaining portion in second and subsequent pressing step. After the first pressing step, since the mold once the release, it is possible to suppress the out-of-plane deformation that increases with the progress of the press molding. Wrinkles result, thin thickness, and / or the workpiece of high strength, has a step portion, and be formed into a press-molded article having a broad top plate width, due to too meat the occurrence can be suppressed.
[0045]
　Subsequently, the present inventors have found that in order to confirm the effect of the above-mentioned ideas, was simulated by FEM.
[0046]
　7 to 9 are diagrams showing the simulation results in the case of forming a press-molded article shown in FIG. 1 in two press forming. 7 to 9 show the shape of the workpiece during the forming of the vertical wall portion. In the simulation shown in FIGS. 7 to 9, shaped to the top plate portion and the ridge portion of the press-molded product shown in FIG. 1 in one step eyes were molded the rest in two steps first. Figure 7 is one step th press molding is completed, an intermediate molded article when the mold release. Figure 8 shows a state during press forming two step eyes. Figure 9 shows a press-molded product when the press molding of the second step first is completed. Further, the formed height of 7 to 9 is the same as the forming height of 3 to 5.
[0047]
　As shown in FIG. 7, the meat-odd workpiece region interim flange portion 16 of the intermediate molded article 11 Y (corresponding to the region X in FIG. 3) was smaller than in the case shown in FIG. Then, to obtain a press-molded article 1 by press-forming the intermediate molded article 11 is molded in one step first in two steps first. As shown in FIG. 9, wrinkles to be read from the main curvature of the vertical wall portion 3b and the step bottom directly below the vertical wall portion 3c immediately below the stepped portion of the press-molded product 1 is significantly compared to the press-molded article shown in FIG. 5 It was suppressed. This will be described with reference to FIG. 10.
[0048]
　Figure 10 is a diagram showing the magnitude of the shear strain at any point of the vertical wall portion 3b immediately below the stepped portion with the progress of the press forming. The vertical axis of FIG. 10 shows the magnitude of the shear strain, the horizontal axis represents the formed height of the vertical wall portion 3a immediately below the stepped upper. Black circle in FIG. 10 shows the results obtained by molding in a single pressing step. White triangles in FIG. 10 shows a process first results of the results when molded in two pressing step. Black triangles in FIG. 10 shows a second step first results of the results when molded in two pressing step. Region A in FIG. 10, forming height represents the point about 10 mm, corresponds to the state of FIG. 3 and FIG. Region B in FIG. 10, forming height represents the point about 23 mm, which corresponds to the state shown in FIG. 4 and FIG. The area C in FIG. 10 corresponds to the state of FIG. 5 and FIG.
[0049]
　In the region A in FIG. 10, the shear against the shearing strain when molded in one pressing step (black circles) in the range of about 0.08, when molded in two pressing step (open triangle) strain is about 0.05. As described above, when molded by two pressing step, by molding the intermediate molded article comprising a provisional flange portion, because the shear strain is suppressed. Further press forming proceeds from the point of the area A, in the case of molding the case molded in one pressing step and two pressing step, changes in the magnitude of the shear strain is the same tendency. In short, as shown in a region A in FIG. 10, when forming the provisional flange portion, shear strain of the vertical wall portion 3b immediately below the stepped portion can be suppressed. As a result, shear strain of the final product can be suppressed. That is, the size of the wrinkles is suppressed.
[0050]
　Method for manufacturing a press molded product of the present embodiment has been completed based on the above findings. Hereinafter, a method for manufacturing a press molded product of the present embodiment.
[0051]
　Method for manufacturing a press molded product of the present embodiment includes a first pressing step and a second pressing step. In the first press step, by using a first mold, molding the intermediate molded article from the workpiece. In a second press step using the second die, molding the intermediate molded article molded in the first pressing step the press-molded product.
[0052]
　Intermediate molded article]
　FIG 11 is a perspective view of an intermediate molded article obtained by the first pressing step. Intermediate molded article 11 has a top wall 12, a ridgeline portion 15, and the provisional vertical wall portion 13, the provisional edge line portion 17, and a provisional flange portion 16. The top plate portion of the intermediate molded article 11 12 has the same shape as the top plate 2 of the press-molded product 1 (Completed) shown in FIG. Thus, the top wall 12 of the intermediate molded article 11 has a stepped portion 14. Ridge portion 15 at the end portion 12A in the width direction of the top plate 12.
[0053]
　Preliminary vertical wall portion 13 has a shape of at least part of the vertical wall portion of the press-molded product. In other words, provisional vertical wall 13 has the shape of a halfway of the vertical wall portion of the press-molded product. Preliminary vertical wall portion 13 is adjacent to top wall 12 via the ridge portion 15. Angle of provisional vertical wall portion 13 and the top plate portion 12 is perpendicular or obtuse for normally releasing. There is provisional ridge portion 17 at the end opposite to the ridge line portion 15 of the provisional vertical wall portion 13. Preliminary flange portion 16 is adjacent to the provisional vertical wall portion 13 through the interim ridge portion 17. As shown in FIG. 19, the intermediate molded article includes a top plate 2c of the step bottom of the press-molded article 1, the ridge portion adjacent to the stepped bottom of the top plate portion 2c, the stepped bottom through the ridge it may not have a provisional vertical wall portion adjacent the top plate 2c.
[0054]
　First mold]
　FIGS. 12 to 14 are sectional views showing a state in which the metal plate 25 is formed into the stepped portion 14 in the first press step stepwise. Of these figures, FIG. 12 shows the arrangement of the mold and the workpiece prior to the start forming. Figure 13 shows the molding initial state. Figure 14 shows a state during molding completed.
[0055]
　12-as shown in Figure 14, the first mold 20 includes a first punch 21 as the lower mold includes a first die 22 and the first pad 23 as the upper die. That is, the first punch 21 faces the first die 22 and the first pad 23. The first mold 20, for molding the metal plate 25 to the intermediate product 11 shown in FIG. 11.
[0056]
　The first punch 21 has a first tip portion 21a, the first punch wall portion 21b, and a punch flat portion 21c. The first end 21a extends in the width direction of the end portion of the first punch 21 has a stepped portion in the longitudinal direction across a portion of the width direction of at least the first punch 21. That is, the shape of the first tip portion 21a of the first punch 21 corresponds to the top plate portion of the intermediate molded article. The first punch wall portion 21b, adjacent to the first end 21a through a first punch shoulder 21d at the end there is a step portion of the first tip portion 21a. That is, the shape of the first punch wall portion 21b corresponds to the provisional vertical wall of the intermediate molded article. The first punch shoulder 21d is a shape corresponding to the ridge portions of the intermediate molded article. Punching the flat portion 21c is adjacent to the first punch wall portion 21b through the first punch wall portion 21b and the punch Sokokata 21e. That is, the shape of the punch flat portion 21c corresponds to the provisional flange portion of the intermediate molded article. The shape of the punch Sokokata 21e corresponds to the provisional ridge portion of the intermediate molded article.
[0057]
　The first die 22 includes first punch shoulder 21d of the first punch 21, facing the first punch wall portion 21b and the punch flat portion 21c. By the first die 22 and the first punch 21, a region other than the top plate portion of the intermediate molded article is molded.
[0058]
　The first pad 23 is opposed to the first end 21a of the first punch 21. By the first pad 23 and the first punch 21, the top plate portion of the intermediate molded article is molded. The first pad 23 is attached to the first die 22 via the pressure member 24. Pressure member 24 is, for example, springs, rubber, hydraulic cylinder or the like.
[0059]
　The first die 20 is disposed on the first pressing machine 51 (see FIG. 23). The first press 51 is bent forming the pad a metal plate 25. Hereinafter, a first mold for explaining the first pressing step by the first pressing machine installed.
[0060]
　First press step]
　As shown in FIGS. 12 to 14, in the first press step, as the workpiece (blank) using the metal plate 25. As the metal plate 25, for example, tensile strength or 590 MPa, preferably using the above high-strength steel sheet 980 MPa. Because high yield point of the workpiece of the intensity high, wrinkles are likely to occur. The manufacturing method of this embodiment is suitable for press forming of the workpiece in such a high intensity. As the metal plate 25 can plated steel, stainless steel, alloy steel plate, aluminum alloy plate, also possible to use copper alloy plate or the like. Not a metal plate but also the present invention to a plastic sheet softened can be applied.
[0061]
　As shown in FIG. 12, to place a metal plate 25 at a predetermined position of the first punch 21. Metal plate 25 is disposed in contact with the first end 21a and the first punch shoulder 21d. The metal plate 25 is disposed between the punch flat portion 21c and the first die 22. Then, the first pad 23 and the first die 22 approaches the first punch 21. Then, to the state shown in FIG. 13.
[0062]
　As shown in FIG. 13, sandwiching the metal plate 25 and the first pad 23 by the first front end portion 21a of the first punch 21. The first pad 23 is desirably not press the portion to be molded into ridge portion of the metal plate 25. That is, it is preferable not to pinch the metal sheet 25 between the first pad 23 and the punch shoulder. That it is the occurrence of wrinkles can be suppressed. The first pad 23 is most desirable to suppress to the vicinity of the portion to be molded into ridge portion of the metal plate 25. When the first die 22 further approaches the first punch 21, the pushing begins to the first die 22 of the metal plate 25 by the first punch 21 begins the bending of the metal plate 25. Further when the first die 22 approaches the first punch 21, pushing the first punch 21 with respect to the first die 22 reaches the bottom dead center, to the state shown in FIG. 14.
[0063]
　As shown in FIG. 14, when it reaches the molding bottom dead center, the intermediate molded article 11 is obtained.
[0064]
　Referring to FIG. 11, in a first pressing step, by forming a provisional flange portion 16, and at the same time to restrain the meat-odd regions during molding interim vertical wall portions 13 X (see FIG. 3), molded under meat more than the area X can be crushed in a mold at dead center. As a result, it is possible to suppress the meat-odd regions X. Further, in the first pressing step, elastic recovery the workpiece by the intermediate molded article release occurs. It can be alleviated shear distortion of the vertical wall portion 3b immediately below the stepped portion by elastic recovery.
[0065]
　Forming height of the first vertical wall portion 3a of the step top immediately below the intermediate molded article to be molded by a press process, more than 50% of the forming height of the press-molded product is preferably a final finished product. That is, the height of the provisional vertical wall of the intermediate molded article is preferably not more than 50% of the height of the vertical wall portion of the press-molded product. The height of the vertical wall portion of the press-molded product, means the height of the vertical wall portion 3a immediately below the stepped upper. Particularly preferably, in the first pressing step, the entire region of the ridge line portion of the press-molded product is molded. As shown in region A of FIG. 10, the shear strain of the vertical wall portion 3a immediately below the stepped upper when forming the ridge portion of the press-molded product increases sharply. If molded intermediate product all regions have been formed corresponding to the ridge portions of the press-molded product in the first pressing step, because the shear strain can be largely suppressed. Most preferred are further provisional vertical wall portion adjacent to the step bottom of the top plate portion 2c is that unformed.
[0066]
　In the first pressing step described above has been described a case where bending a workpiece. However, the first press step is not limited to bending. In the first pressing step may be molded intermediate molded article by drawing.
[0067]
　Figure 15 is a sectional view showing a first mold when carrying out the draw forming in a first pressing step. The first mold 40 includes a first punch 41 and the blank holder 43 as the lower mold includes a first die 42 as an upper mold. That is, the first die 42, opposite to the first punch 41 and the blank holder 43. The first mold 40 for molding the metal plate 25 to the intermediate product 11 shown in FIG. 11.
[0068]
　The first punch 41 has a first tip portion 41a, a first punch wall portion 41b. The first end 41a extends in the width direction of the end portion of the first punch 41 has a stepped portion in the longitudinal direction across a portion of the width direction of at least the first punch 41. That is, the shape of the first tip portion 41a of the first punch 41 corresponds to the shape of the top plate portion of the intermediate molded article. The first punch wall portion 41b is adjacent to the first end 41a through a first punch shoulder 41d at the end there is a step portion of the first tip portion 41a. That is, the shape of the first punch wall portion 41b corresponds to the shape of the provisional vertical wall of the intermediate molded article. The shape of the first punch shoulder 41d corresponds to the shape of the ridge line portion of the intermediate molded article.
[0069]
　Blank holder 43 is disposed adjacent to the first punch 41. Blank holder 43, facing the first die 42. The blank holder 43 and the first die 42, the provisional flange portion of the intermediate molded article is molded. Thus, the shape of the blank holder 43 corresponds to the shape of the provisional flange portion of the intermediate molded article. Further, the blank holder 43 is attached to a press machine (not shown) via a pressure member 44. Pressure member 44 is, for example, springs, rubber, hydraulic cylinder or the like.
[0070]
　The first die 42, opposite to the first punch 41 and the blank holder 43. By the first die 42 and the first punch 41 and the blank holder 43, intermediate molded article is molded. Thus, the shape of the first die 42 corresponds to the shape of the intermediate molded article.
[0071]
　When a molded first pressing step is diaphragm, first, sandwiching the metal plate 25 by the blank holder 43 and the first die 42. Then, the first punch 41 intermediate product is pressed in the first die 42 is obtained.
[0072]
　In short, in the first pressing step, one of the mold of the first mold 40 shown in the first mold 20 or 15 shown in FIG. 12 can also be used.
[0073]
　Referring to FIG. 23, in the manufacturing method of this embodiment, after the first press step, carrying out the second pressing step. The second die 30 is placed on the second pressing machine 52. The following describes a second pressing step.
[0074]
　[Press molded article]
　press molded article obtained by the second pressing step is a press-molded product having a step portion in the top plate as shown in FIG.
[0075]
　Second mold]
　FIGS. 16 to 18 are sectional views showing a second pressing step in stages. Of these figures, FIG. 16 shows a state before start forming. Figure 17 shows the molding initial state. Figure 18 shows a state during molding completed.
[0076]
　As shown in FIGS. 16 to 18, the second die 30 is provided with a second punch 31 as a lower mold, a second die 32 and the second pad 33 as the upper die. That is, the second punch 31 faces the first die 32 and the first pad 33. The second mold 30 for molding the intermediate molded article 11 obtained in the first pressing step the press molded article 1 shown in FIG.
[0077]
　The second punch 31 has a second tip portion 31a, and a second punch wall portion 31b. Shape of the second tip portion 31a is the same as the shape of the first tip portion 21a of the first punch 21 of the first die 20 (see FIG. 12). That is, the shape of the second tip portion 31a corresponds to the shape of the top plate of the press-molded product. The second punch wall portion 31b is adjacent to the second distal end portion 31a via the second punch shoulder 31d at the end there is a step portion of the second tip portion 31a. That is, the shape of the second punch wall portion 31b corresponds to the shape of the vertical wall portion of the press-molded product. Shape of the second punch shoulder 31d corresponds to the shape of the ridge line portion of the press-molded product.
[0078]
　The second die 32, the second punch shoulder 31d of the second punch 31, facing the second punch wall portion 31b. By the second die 32 and the second punch 31, a region other than the top plate of the press-molded product is molded. Thus, the shape of the second die 32 corresponds to the shape of the second punch 31.
[0079]
　The second pad 33 is opposed to the second distal end portion 31a of the second punch 31. In the second pad 33 and the second punch 31, to sandwich the top plate portion of the intermediate molded article. Thus, the shape of the second pad 33 corresponds to the shape of the second tip portion 31a of the second punch 31. The second pad 33 is attached to the second die 32 via the pressure member 34. Pressure member 34 is, for example, springs, rubber, hydraulic cylinder or the like.
[0080]
　The second die 30 is placed on the second pressing machine, not shown. The second press machine, bending molding the intermediate molded article pad. Hereinafter, a second mold for explaining the second pressing step by the second pressing machine installed.
[0081]
　Second press process]
　as shown in FIG. 16, to place the intermediate molded article 11 molded by the first pressing step to the predetermined position of the second punch 31. Thereafter, the second pad 33 and the second die 32 approaches the second punch 31. Then, to the state shown in FIG. 17.
[0082]
　As shown in FIG. 17, the second pad 33 and the second punch 31 sandwich the top plate portion of the intermediate molded article 11. Thus, the intermediate molded article 11 is restrained. The second pad 33 and the second punch 31, to the entire area of ​​the top plate portion of the intermediate molded article 11 may be constrained, or in some areas. Region intermediate molded article 11 is constrained, wrinkles, is appropriately set in consideration of the dimensional accuracy of the molded article.
[0083]
　When the second die 32 is further closer to the second punch 31, the pushing begins to second die 32 of the intermediate molded article 11 by the second punch 31, the bending of the intermediate molded article 11 begins. In the second press step, the molding is moved toward the provisional ridge portion 17 of the intermediate molded article 11 to the provisional flange portion 16. That is, after the provisional flange 16 is bent in order order second die die shoulder, will be stretched between the second die 32 of the second punch 31. Accordingly, the provisional flange portion 16 is formed into a vertical wall 3 of the press-molded product 1. If it is further closer to the second die 32 to the second punch 31, pushing the second punch 31 for the second die 32 reaches the bottom dead center, to the state shown in FIG. 18.
[0084]
　As shown in FIG. 18, when it reaches the molding bottom dead center, the press-molded product 1 is obtained.
[0085]
　In a second press process, in order to mold the provisional flange portion 16 to the vertical wall portion 3 to move the provisional ridgeline portion between the provisional flange 16 provisionally vertical wall portion 13 to the flange side. Since the position of the provisional ridge portion which moves at the same height regardless of the shape of the top plate, the meat more than in the second pressing step is less likely to occur. Further, in the second press step when moving the provisional ridge portions, since the tension in the provisional vertical wall portion 13 occurs, the meat more than that produced in the first press step is reduced. Thus, wrinkles produced in the vertical wall portion 3b and the vertical wall portion 3c of the right under the stepped bottom just below the stepped portion of the press-molded product 1 can be suppressed.
[0086]
　The height H2 of the second punch wall portion 31b of the second pressing machine (second die 30) (see FIG. 16), the first punch wall portion of the first pressing machine (first mold 10, 30) 11b, greater than the height of 31b H1 (see FIG. 12). In other words, forming height of the second pressing step is greater than the formed height of the first pressing step. Intermediate molded article to be molded in the first pressing machine has a provisional flange portion. With the above configuration, it can be formed by suppressing the wrinkles high strength steel plate press-formed article, as shown in FIG.
[0087]
　After the second press step, or puncture the press-molded product may be carried out trimming step of excising unnecessary portions of the press-molded product.
[0088]
　Others The invention is not limited to the above embodiments, without departing from the scope of the present invention, it is needless to say various modifications are possible. For example, in the press forming apparatus of the above embodiment, comprises a punch as a lower mold, but a configuration in which a die and a pad as an upper mold, may be configured such that the arrangement of the upper and lower molds are inverted in the vertical Absent.
Example
[0089]
　In order to confirm the effect of suppressing wrinkles due to the manufacturing method of the present embodiment was conducted simulation by FEM. In the simulation, it was variously changed tensile strength of the workpiece. The simulation assumed a case of forming the shape of the press-molded product shown in FIG. As the present invention example, assuming a case of molding the press-formed product in two pressing step. As a comparative example, assuming a case of forming a press-formed product in a single pressing step. In the present invention example was carried out the second pressing step using a first pressing step, and the second mold with the workpiece which is a flat steel plate first mold.
[0090]
　Figure 19 is a perspective view showing an intermediate product of the present invention embodiment. In the first pressing step of the present invention example was molded intermediate product 11 shown in FIG. 19. Intermediate molded article 11 is provided, the top wall 12 has a stepped portion 14, the provisional vertical wall 13, and the provisional flange portion 16. In the second pressing step of the present invention example was molded intermediate product 11 in a press-molded product shown in FIG.
[0091]
　The dimensions of the press-molded product obtained by molding in the present invention will be described. Width W1 of the top plate portion of the step top of the press-molded product was 90 mm (see Figure 1). Width W2 of the top plate portion of the step bottom of the press-molded product was 80 mm. Forming height H1 of the top plate portion of the step top of the press-molded product was 40 mm. Forming height H2 of the top plate portion of the step bottom of the press-molded product was 35 mm. That is, the height H of the step portion was 5 mm. The radius of curvature R of the ridge line portion of the press-molded product was 6 mm.
[0092]
　Workpiece used in molding experiments of this example was used JAC270DC defined by the Japan Iron and Steel Federation Standards, JAC590R, the steel plate corresponding to JSC980Y and JAC1180Y. In other words, the tensile strength of JAC270DC was 270MPa. The tensile strength of the JAC590R was 590MPa. The tensile strength of the JSC980Y was 980MPa. The tensile strength of the JAC1180Y was 1180MPa.
[0093]
　It was investigated principal curvatures 1 / [rho at any point of the vertical wall portion 3c of the right under the stepped bottom of the present invention examples and comparative examples shaped press-molded product. To calculate the difference △ 1 / ρ between the maximum value and the minimum value of the main curvature 1 / ρ, it was used as an index of evaluation of wrinkles. △ 1 / [rho is the image data was collected using a formed article 3-dimensional shape measuring instrument (e.g. Steinbichler Optotechnik GmbH Co. COMET V, etc.) was calculated using an image processing software (e.g. JSOL Co. JSTAMP-NV, etc.) .
[0094]
　Figure 20 is a graph showing the results of the present invention and comparative examples. The vertical axis of FIG. 20 shows the difference △ 1 / [rho maximum value and the minimum value of the principal curvatures. Of the bar graph shown in FIG. 20, open bars indicate the results of the present invention example, hatched bars show the results of a comparative example.
[0095]
　As shown in FIG. 20, the tensile strength of the workpiece may be more 590 MPa, the inventive examples were significantly less △ 1 / [rho than the comparative example. That is, when the tensile strength of the workpiece is not less than 590 MPa, the inventive examples significantly in wrinkling compared with Comparative Example was suppressed. The tensile strength of the workpiece even when the 270MPa, △ 1 / ρ of the present invention example was smaller than the comparative example. Accordingly, the tensile strength of the workpiece even when less than 590 MPa, examples present invention could suppress wrinkles of the press-molded product.
DESCRIPTION OF SYMBOLS
[0096]
　　1 press-molded product
　　2 the top plate portion
　　3a stepped vertical wall portion of the upper right under
　　the vertical wall portion immediately below 3b stepped portion
　　vertical wall immediately below 3c step lower
　　4 stepped portion
　　5 ridge
　　6 flange portion
　11 intermediate product
　12 top plate ( intermediate molded article)
　13 provisional vertical wall portion
　14 stepped portion (intermediate
　product) 15 ridge portion (intermediate
　product) 16 provisional flange portion
　17 provisional ridge
　20 first die
　21 first punch
　22 first die
　23 first pad
　24 pressing member
　25 workpiece
　30 second mold
　31 second punch
　32 second die
　33 second pad
　51 first pressing machine
　52 second pressing machine

WE CLAIM

Extending from the end portion in the width direction, and a top plate portion having a step portion in the longitudinal direction across at least a portion of the width direction, the ridge portions on the end portion in the width direction in which the there is a step portion of the top plate a vertical wall portion adjacent to the top plate portion through a method for manufacturing a press molded article comprising,
　by using the first mold, and the step portion of the top plate portion, via the ridge portion a provisional vertical wall portion which at least part of the shape of the vertical wall portion is formed adjacent to the top plate portion Te, the provisional edge line portion located at the opposite end to the ridge line portion of the provisional vertical wall a first pressing step for molding the intermediate molded article from the workpiece with a provisional flange portion adjacent to the provisional vertical wall portion through,
　using a second mold, the top of the intermediate molded article formed to move toward the provisional ridge while restraining at least a portion of the plate portion to the provisional flange portion Wherein comprising a second pressing step of forming the intermediate product of the press molded product, a method for producing a press-molded article.
[Requested item 2]
　A method of press-molded product produced according to claim 1,
　the height of the adjacent said top plate portion of the lower of the step portion of the intermediate molded article has the provisional vertical wall portion of the press-molded product wherein 50% or less of the vertical wall portion of the height, the manufacturing method of the press-molded product.
[Requested item 3]
　A method of press-molded product produced according to claim 1,
　wherein in the first pressing step, the entire region of the ridge portion of the press-molded product is molded, the manufacturing method of the press-molded product.
[Requested item 4]
　A method of press-molded product produced according to any one of claims 1 to 3,
　the tensile strength of the workpiece is more 590 MPa, method of manufacturing press-molded product.
[Requested item 5]
　A method of press-molded product produced according to any one of claims 1 to 3,
　the tensile strength of the workpiece is more 980 MPa, method of manufacturing press-molded product.
[Requested item 6]
　A method of press-molded product produced according to any one of claims 1 to 5,
　the height H of the step portion of the press-molded article, the radius of curvature of the ridge line portion of the press-molded product It satisfies the following equation (1) with respect to R, the manufacturing method of the press-molded product.
　H ≧ 0.4R (1)
[Requested item 7]
　Extending from the end portion in the width direction, the first end having a step portion in the longitudinal direction across at least a portion of the width direction, the first punch shoulder in the end there is a step portion of the first distal portion the first punch wall portion adjacent to the first end through, and a first punch having a punching flat portion adjacent to the first punch wall portion through the first punch wall and the punch bottom shoulder,
　said said first punch shoulder of the first punch, the first first die facing the punch walls and the punch flat portion,
　including a first pad which faces the first end of the first punch, a first and press
　a second tip portion of the same shape as the first tip, a second adjacent to through a second punch shoulder in the end there is a step portion of the second tip and the second tip portion punch wall, a second punch having a
　second punch of the second punch shoulder, and Serial second second die facing the punch wall,
　the second pad facing the second end portion of the second punch, wherein the second pressing machine located downstream of the first pressing machine, with a
　height of the second punch wall portion of the second pressing machine it is greater than the height of the first punch wall portion of the first pressing machine, the production line.
[Requested item 8]
　Extending from the end portion in the width direction, the first end having a step portion in the longitudinal direction across at least a portion of the width direction, and the first punch shoulder in the end there is a step portion of the first distal portion the first punch wall portion adjacent to said first end via a first punch having a
　first blank holder adjacent to the punch,
　including a first die facing the first punch and the blank holder, the a first pressing machine,
　adjacent the second distal end of the same shape as the first tip and the second tip portion of the second punch and the second tip portion via a shoulder at the end there is a step portion to the second punch wall, a second punch having a
　second punch of the second punch shoulder, and a second die facing the second punch wall portion,
　facing the second end portion of the second punch wherein pads, and located downstream of the first pressing machine Comprising a second press machine, a
　height of the second punch wall portion of the second pressing machine is greater than the height of the first punch wall portion of the first pressing machine, the production line.