0001]The present invention is press-molded article of a material metal sheet by press molding: for Press device and a manufacturing method thereof for manufacturing (eg lower arm automobile).
BACKGROUND
[0002]In automobiles, the wheels attached to the vehicle body via a suspension device (suspension). One of members constituting the suspension device is a lower arm. Automotive lower arm (hereinafter, simply referred to as "lower arm") one end of is attached to the vehicle body via the (suspension member specifically) frame of the suspension. At the other end of the lower arm (specifically, wheel) wheel is mounted.
[0003]
　It shows an example of the lower arm in FIG. Press-molded article 1 shown in FIG. 1 includes a main body portion 2, and a protrusion 3. The body portion 2 is L-shaped or arcuate. Of both ends of the main body 2, one end portion (hereinafter, also referred to as a "first end portion") 2a is an end portion attached to the automobile body. The other end (hereinafter, also referred to as a "second end portion") 2b is an end portion attached to a car wheel. Incidentally, in FIG. 1 shows the side to be connected to the wheel by the symbol "WH" indicates a side to be connected to the vehicle body by the symbol "B".
[0004]
　Projections 3 protrudes to the outside of the curvature of the main body portion 2. In Figure 1, (in other words, approximately in the middle of the first end 2a and a second end portion 2b) approximately halfway the longitudinal direction of the body 2 projecting portion 3 is provided. Protrusion 3 is also a portion mounted to an automobile body.
[0005]
　Sectional shape of the body portion 2 and the projections 3 are both a groove shape. That is, the main body portion 2 and the protrusion 3 includes respectively, a top plate 4, the two vertical wall portions, namely 5a, two from among 5b and 5c, and. Vertical wall portion 5a, extending between the first end 2a and a second end 2b of the main body portion 2 of the main body 2 of the press-molded product 1. Vertical wall 5b extends between a first end 2a of the body portion 2 of the protruding portion 3. Vertical wall portion 5c extends between the projections 3 and the second end 2b of the main body portion 2. Hereinafter, the vertical wall portion indicates that the vertical wall portion 5a in FIG. 1, reference numeral is 5. Vertical wall 5, as shown in FIG. 1, the curved protruding portion 3 (hereinafter, simply referred to as "curved inside"). Top plate 4 is connected via the ridge portion 6 to the vertical wall 5. Ridge 6 is curved in top plate 4 side. Top plate 4 includes a rim portion 7 and concave portion 8. Edge 7 is adjacent to the ridge portion 6. Recesses 8, along the edge 7. The recess 8 has an inner wall surface 8c and the bottom surface 8b. Bottom 8b of recess 8 has an end 8a.
[0006]
　In Figure 1, the recess 8, the surface of the top plate 4 of the main body portion 2 is provided in the region of the protrusion 3 to the vicinity of the first end 2a and a second end 2b.
[0007]
　Such press-molded article 1 of the shape is manufactured material metal plate (blank) by press-forming. There is the following for the prior art relates to press forming press forming.
[0008]
　Japanese Patent 2007-144507 (Patent Document 1), the method for producing a press-molded article having excellent shape fixability is disclosed. When forming the vertical wall portion of the press-molded product, the vertical wall portion bent, for receiving the deformation by bending back, the vertical wall portion tends to warp (easier to spring back). In the manufacturing method of Patent Document 1 To solve this warp, the vertical wall portion is formed into a corrugated shape. Thus, warpage of the vertical wall portion (spring back) is suppressed, and is described in Patent Document 1.
CITATION
Patent Document
[0009]
Patent Document 1: JP 2007-144507 JP
Summary of the Invention
Problems that the Invention is to Solve
[0010]
　However, lowering the car underbody part as represented in the lower arm of the manufacturing method described in Patent Document 1 is applied to the production of (suspension components) and the like, (including fatigue resistance) components of the performance molded sometimes. In particular, underbody parts, because the cyclic loading is acted upon by vibrations caused during the running of the automobile, fatigue resistance is required.
[0011]
　Figure 2A ~ 2C are of the press-molded product used in the lower arm is a cross-sectional view showing an example of a typical manufacturing process. The case of producing a press-molded article 1 shown in FIG. 1 will be described. Figure 2A, in a general manufacturing process, a diagram illustrating a stage before the press molding. Figure 2B, in the general manufacturing process diagrams showing the steps in press molding. 2C is in a general production method is a diagram showing the steps in press molding ends.
[0012]
　When producing a press-molded article 1 shown in FIG. 1, as shown in FIG. 2A, the first die 101 and second die 102 is used as the upper die, punch 103 facing the upper die as a lower die is used. The first die 101 and second die 102 is disposed on the lower side of the upper holder 104. Punch 103 is supported by lower holder 105. Upper holder 104 is attached to a slide (not shown).
[0013]
　First, as shown in FIG. 2A, placing the blank S made of a metal plate or the like at a predetermined position of the punch 103. Blank S is provided with a recess 106 which is formed in advance by press molding. Blank S is provided with a recess having the same shape as the press-molded product of the recess as a final product. Thereafter, the slide (not shown) is lowered, the first die 101 and second die 102 also drops.
[0014]
　Next, as shown in Figure 2B, first, to sandwich the concave portion 106 of the blank S in the first die 101 and the punch 103. Thereafter, as shown in Figure 2C, the slide is further lowered, the molding of the second die 102 and the punch 103 is completed. That is, while restraining the recess 106 of the blank S by the first die 101 and the punch 103, and forming a vertical wall portion 107 by the second die 102 and the punch 103, the press-molded product 100 is obtained.
[0015]
　Figure 3 is an enlarged view of a ridge line near the press-molded product in Figure 2C. When the second die 102 reaches the molding bottom dead center, on the back side of the ridge portion 108 of the press-molded product 100 (punch 103 side in FIG. 3), compressive stress occurs. The first die 101 and second die 102 is releasing, the constraint is released, the restoring force acts in the direction of the arrow in FIG. 3, the press molded product 100 is to return to the shape before molding (hereinafter, this phenomenon is also referred to as spring back). Displacement by restoring force (hereinafter, referred to as the spring back amount) is large, on the back side of the ridge portion 108 of the press-molded product 100, a tensile stress remains occur on behalf of the compressive stress (hereinafter, the tensile stress remaining also referred to as a residual tensile stress). Press-molded product having a residual tensile stress, when the repeated load is loaded, cracks are likely to occur in a portion having a residual tensile stress. That is, the press-molded product is to have a residual tensile stress, fatigue resistance is lowered. In particular, fatigue resistance of the lower arm having a vertical wall portion 5 which is curved inwardly as shown in Figure 1, tends to decrease. For forming of the vertical wall portion 5 which is curved inwardly is stretch flangeability, compressive stress on the back side (inner side of the cross section) of the ridge portion 6 is likely to occur in the molding bottom dead center, because the spring back amount tends to be large .
[0016]
　If the production of the press-molded product such as a lower arm applying the manufacturing method of Patent Document 1, the residual stress of the ridge portion is not sufficiently reduced. Therefore, in the manufacturing method of Patent Document 1 is not sufficient to suppress the spring back which lowers the fatigue resistance of the press-molded product mentioned above.
[0017]
　Furthermore, the manufacturing method described in Patent Document 1 is directed to a part having a constant cross-section. Therefore, for example, such as lower arm, be applied to a part having a vertical wall portion which is curved in a top plate portion and the parts longitudinally with a recess (ridge portion), it can not be ensured excellent fatigue resistance.
[0018]
　The present invention has been made in view of the above circumstances. An object of the present invention is to provide a press device and a manufacturing method thereof for manufacturing a press molded article decrease in fatigue resistance is suppressed.
Means for Solving the Problems
[0019]
　Press device according to an embodiment of the present invention comprises a punch, a first die, a second die, the. Punch has a top surface, a side surface, and a punch shoulder connecting the top surface and the side surface, the. Punch shoulder is curved on the top side. The top surface recesses are formed. The first die is disposed opposite the recess in the punch. The first die has a convex portion having a shape corresponding to the recess. The convex portion having a shape corresponding to the recess, which means a convex portion concave shape is inverted. Strictly corresponding to the thickness of the blank, the convex portion than the concave portion is small. The second die is disposed adjacent to the first die. The second die has a concave shape corresponding to the punch shoulder and the side surface of the punch. The concave shape corresponding to the punch shoulder and the side surface of the punch means an inverted shape as the shape of the punch shoulder and the side surface of the punch. In the press molding, after the second die has reached the molding bottom dead center, the first die reaches the molding bottom dead center. To do so, the pressing device is mechanically or electrically controlling the movement of the first die and the second die.
[0020]
　If mechanical control, the press apparatus further includes an upper holder which is disposed above the first die and the second die, a first pressure member disposed between the upper holder and the first die, the upper comprising a second pressure member disposed between the holder and the second die, the. Edge adjacent to the first die extending from the second die concave is lower than the edge adjacent to the second die extending from the convex portion of the first die position. Therefore, in the press forming, after the second die has reached the molding bottom dead center, the first die reaches the molding bottom dead center.
[0021]
　Further, a portion of the first die may be disposed between the upper holder and the second pressure member. In this case, the pressing apparatus includes an upper holder which is disposed above the first die, a first pressure member disposed between the upper holder and the first die, the first die in the upper side of the second die first 2 and a second pressure member disposed between the dies. Edge adjacent to the first die extending from the second die concave is lower than the edge adjacent to the second die extending from the convex portion of the first die position. Therefore, in the press forming, after the second die has reached the molding bottom dead center, the first die reaches the molding bottom dead center. Pressure of the first pressure member is greater than pressure of the second member. When towards the pressure of the second member than the pressure of the first pressure member is larger it becomes impossible pressed at the first die.
[0022]
　When electrically controlled, the press device further comprises a control mechanism which controls the movement of the first die and second die. Control mechanism, to reach the first die to the molding bottom dead center after allowed to reach second die to the molding bottom dead center. Therefore, in the press forming, after the second die has reached the molding bottom dead center, the first die reaches the molding bottom dead center.
[0023]
　Press device according to an embodiment of the present invention comprises a punch, a first die, a second die and a third die. Punch has a top surface, a side surface, and a punch shoulder connecting the top surface and the side surface, the. Punch shoulder is curved on the top side. The top surface recess having a bottom surface and the inner wall surface is formed. The first die is disposed to face at least an inner wall surface of the concave portion of the punch. The first die has a convex portion having a shape corresponding to the inner wall surface of the recess. The convex portion having a shape corresponding to the inner wall surface, which means a convex portion which the inner wall surface and shape inverted. The second die is disposed adjacent to the first die. The second die has a concave shape corresponding to the punch shoulder and the side surface of the punch. The third die is disposed adjacent to the first die. The third die, the second die across the first die is disposed on the opposite side. In the press molding, after the third die has reached the molding bottom dead center, the second die reaches the molding bottom dead center. After the second die has reached the molding bottom dead center, the first die reaches the molding bottom dead center. To do so, the pressing device is mechanically or electrically controlling the first die, the movement of the second die and the third die.
[0024]
　If controlled mechanically, the press apparatus further includes an upper holder, a first pressing member, and a second pressure member, and the third pressing member, a. Upper holder is arranged on the upper side of the first die and the second die and the third die. The first pressure member is disposed between the upper holder and the first die. The second pressing member is disposed between the upper holder and the second die. The third pressure member is positioned between the upper holder and the third die. Punch side edge adjacent to the first die of the third die is lower than the edge adjacent to the first die extending from the second die concave position. Edge adjacent to the first die extending from the second die concave is lower than the edge adjacent to the second die extending from the convex portion of the first die position. Therefore, in the press forming after the third die has reached the molding bottom dead center, the second die reaches the molding bottom dead center. After the second die has reached the molding bottom dead center, the first die reaches the molding bottom dead center.
[0025]
　Further, a portion of the first die may be disposed between at least one upper holder of the second pressing member and third pressing member. In this case, the pressing apparatus includes an upper holder which is disposed above the first die and the second die, a first pressure member disposed between the upper holder and the first die, disposed on the upper side of the second die comprising a second pressure member being a third pressure member disposed above the third die, the. A second pressing member at least one of the third pressure member is positioned under the first die. Punch side edge adjacent to the first die of the third die is lower than the edge adjacent to the first die extending from the second die concave position. Edge adjacent to the first die extending from the second die concave is lower than the edge adjacent to the second die extending from the convex portion of the first die position. Therefore, in the press molding, the third die, the second die, reaches the molding bottom dead center in the order of the first die. Pressure of the first pressure member, greater than the sum of the pressure force of the second pressing member and third pressing member is disposed below the first die. Be due to the direction of the sum of the pressure force of the second pressing member and third pressing member is disposed below the first die than pressure of the first pressure member is large can not be pressed at the first die .
[0026]
　When electrically controlled, the press apparatus further includes a first die, a control mechanism which controls the movement of the second die and the third die. Control mechanism, after reaching the third die to the molding bottom dead center, to reach the second die to the molding bottom dead center. Thereafter, the control mechanism, to reach the first die to the molding bottom dead center. Therefore, in the press forming after the third die has reached the molding bottom dead center, the second die reaches the molding bottom dead center. After the second die has reached the molding bottom dead center, the first die reaches the molding bottom dead center.
[0027]
　Method for producing a press-molded product according to an embodiment of the present invention comprises a first step, a second step. Press-molded product is provided with a top plate portion, and a vertical wall portion, and a ridge line portion connecting the top plate portion and the vertical wall portion. Ridge is curved on the top plate side. The top plate recesses are formed. In the first step, the recess is pressed into the blank with a punch, and the first die, the. Punch has a shape corresponding to the overall shape of the press-molded product. The first die has a shape corresponding to the shape of at least the recess. The shape corresponding to the shape of the recess, means a protrusion recess shape is inverted. Recess of the top plate portion by the convex portion of the first die is molded. In the second step, the punch, and the second die, a vertical wall portion and a ridge portion in the blank using a press-molding. The second die is disposed adjacent to the first die. The second die has a shape corresponding to the shape of at least the vertical wall portion and a ridge portion. To correspond to the shape of the vertical wall portion and the ridge portion is meant to comprise a concave shape along the shape of the vertical wall portion and a ridge portion. The first step is terminated after the second step.
[0028]
　Method for producing a press-molded product according to an embodiment of the present invention comprises a first step, a second step. Press-molded product is provided with a top plate portion, and a vertical wall portion, and a ridge line portion connecting the top plate portion and the vertical wall portion. Ridge is curved on the top plate side. The top plate, the recess having a bottom surface and the inner wall surface is formed. In the first step, at least the inner wall surface in the blank press molded with a punch, and the first die, the. Punch has a shape corresponding to the overall shape of the press-molded product. The first die has a shape corresponding to the shape of the inner wall of at least the recess. In the second step, the punch, and the second die, a vertical wall portion and a ridge portion in the blank using a press-molding. The second die is disposed adjacent to the first die. The second die has a shape corresponding to the shape of at least the vertical wall portion and a ridge portion. In the first step and second step, to sandwich the blank using the punch, and a third die, the. The third die is provided with a shape corresponding to the shape of at least a portion of the bottom surface of the recess of the press-molded product. The first step is terminated after the second step.
Effect of the invention
[0029]
　The method of the pressing device and manufacturing the present invention can suppress a decrease in fatigue resistance of the press-molded product.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030]
[1] Figure 1 is a perspective view showing a shape example of a press-molded article holds the lower arm schematically.
[Figure 2A] Figure 2A, in a general manufacturing process, a diagram illustrating a stage before the press molding.
[Figure 2B] Figure 2B, in the general manufacturing process diagrams showing the steps in press molding.
[Figure 2C] Figure 2C, the general manufacturing process diagrams showing the steps in press molding ends.
FIG. 3 is an enlarged view of a ridge line near the press-molded product in Figure 2C.
[4] FIG. 4 is a sectional view showing a press apparatus of a first embodiment.
[Figure 5A] Figure 5A, in the first step and the second step of the first embodiment, and shows a stage before the press molding.
[Figure 5B] Figure 5B is the press molding process of the first embodiment, and shows a stage during the press forming.
[Figure 5C] Figure 5C, the first and second steps of the first embodiment, and shows the stage of press molding ends.
FIG. 6 is a sectional view enlarging a vicinity of the edge line portion of the lower arm in FIG 5C.
[Figure 7A] Figure 7A, in the first step and the second step of the second embodiment, showing the stage before the press molding.
[Figure 7B] Figure 7B, in the first step and the second step of the second embodiment, showing the steps in press molding.
[Figure 7C] Figure 7C, in the first step and the second step of the second embodiment, showing the steps in press molding ends.
FIG. 8 is that in FIG. 7A ~ 7C, a cross-sectional view showing an example of the first and second steps of the second embodiment using the different blanks.
[9] FIG. 9 is a sectional view showing a press apparatus of a third embodiment.
[10] FIG. 10 is an enlarged view of a punch shoulder near in FIG.
FIG 11A] FIG 11A, in the first step and the second step of the third embodiment and illustrating a stage before the press molding.
FIG 11B] FIG 11B, in the first step and the second step of the third embodiment, showing the steps in press molding.
FIG 11C] FIG 11C, in the first step and the second step of the third embodiment, showing the steps in press molding ends.
[12] FIG 12 is a sectional view showing a modification of the press apparatus of the first embodiment.
[13] FIG. 13 is a sectional view showing a modification of the press apparatus of the third embodiment.
[14] FIG 14 is a sectional view showing a modification of the press apparatus of the first embodiment.
[15] FIG. 15 is a sectional view showing a modification of the press apparatus of the third embodiment.
[16] FIG. 16 is a sectional view showing a modification of the press apparatus of the third embodiment.
DESCRIPTION OF THE INVENTION
[0031]
　Press device according to the present embodiment comprises a punch, a first die, a second die, the. Punch has a top surface, a side surface, and a punch shoulder connecting the top surface and the side surface, the. Punch shoulder is curved on the top side. Recesses are formed in the top surface. The first die is disposed opposite the recess in the punch. The first die has a convex portion having a shape corresponding to the recess. The second die is disposed adjacent to the first die. The second die has a concave shape corresponding to the punch shoulder and the side surface of the punch. In the press molding, after the second die has reached the molding bottom dead center, the first die reaches the molding bottom dead center. To do so, mechanically or electrically controlling the first die and the movement of the second die.
[0032]
　If mechanical control, the press apparatus further includes an upper holder which is disposed above the first die and the second die, a first pressure member disposed between the upper holder and the first die, the upper comprising a second pressure member disposed between the holder and the second die, the. Edge adjacent to the first die extending from the second die concave is lower than the edge adjacent to the second die extending from the convex portion of the first die position. Therefore, in the press forming, after the second die has reached the molding bottom dead center, the first die reaches the molding bottom dead center.
[0033]
　Further, a portion of the first die may be disposed between the upper holder and the second pressure member. In this case, the pressing apparatus includes an upper holder which is disposed above the first die, a first pressure member disposed between the upper holder and the first die, the first die in the upper side of the second die first 2 and a second pressure member disposed between the dies. Edge adjacent to the first die extending from the second die concave is lower than the edge adjacent to the second die extending from the convex portion of the first die position. Therefore, in the press forming, after the second die has reached the molding bottom dead center, the first die reaches the molding bottom dead center. Pressure of the first pressure member is greater than pressure of the second member. When towards the pressure of the second member than the pressure of the first pressure member is larger it becomes impossible pressed at the first die.
[0034]
　When electrically controlled, the press apparatus includes a control mechanism which controls the movement of the first die and second die. Control mechanism, to reach the first die to the molding bottom dead center after allowed to reach second die to the molding bottom dead center. Therefore, in the press forming, after the second die has reached the molding bottom dead center, the first die reaches the molding bottom dead center.
[0035]
　According to the press apparatus of the present embodiment, the molding of the first die is completed later than the molding of the second die. That is, after the second die has reached the molding bottom dead center, the first die reaches the molding bottom dead center. That is, after forming the vertical wall portion of the press-molded product, the recess is molded. Thus, when the blank (workpiece) is machined by the first die, the blank is drawn towards the concave punches. In this case, the material of the blank flows from the vertical wall portion side to the concave side. As the material flows into the concave side, since the direction of the tensile force to the back side of the ridge line portion of the press-molded product is loaded, compressive stress is reduced. As a result, the reduced amount of spring back of the vertical wall portion, the residual stress of the back side of the ridge portion is reduced than before. Accordingly, reduction of fatigue resistance of the lower arm 1 is prevented.
[0036]
　When viewed in cross section perpendicular to the longitudinal direction of the press-molded product, when manufacturing a press molded article having a vertical wall portion on one side only, can be applied following such press.
[0037]
　Press device according to the present embodiment comprises a punch, a first die, a second die, and a third die, the. Punch has a top surface, a side surface, and a punch shoulder connecting the top surface and the side surface, the. Punch shoulder is curved on the top side. Recess having a bottom surface and the inner wall surface on the top surface is formed. The first die is disposed to face at least an inner wall surface of the concave portion of the punch. The first die has a convex portion having a shape corresponding to the inner wall surface of the recess. The second die is disposed adjacent to the first die. The second die has a concave shape corresponding to the punch shoulder and the side surface of the punch. The third die is a neighbor of the first die and the second die across the first die is disposed on the opposite side. In the press molding, after the third die has reached the molding bottom dead center, the second die reaches the molding bottom dead center. After further second die has reached the molding bottom dead center, the first die reaches the molding bottom dead center. To do so, mechanically or electrically controlling the first die and the second die and the movement of the third die.
[0038]
　If mechanical control, the press apparatus further includes an upper holder which is disposed above the first die and the second die, a first pressure member disposed between the upper holder and the first die, the upper comprising a second pressure member disposed between the holder and the second die, and a third pressure member disposed between the upper holder and the third die, the. Punch side edge adjacent to the first die of the third die is lower than the edge adjacent to the first die extending from the second die concave position. Edge adjacent to the first die extending from the second die concave is lower than the edge adjacent to the second die extending from the convex portion of the first die position. Therefore, in the press molding, the third die, the second die, reaches the molding bottom dead center in the order of the first die.
[0039]
　Further, a portion of the first die may be disposed between at least one upper holder of the second pressing member and third pressing member. In this case, the pressing apparatus includes an upper holder which is disposed above the first die and the second die, a first pressure member disposed between the upper holder and the first die, disposed on the upper side of the second die comprising a second pressure member being a third pressure member disposed above the third die, the. A second pressing member at least one of the third pressure member is positioned under the first die. Punch side edge adjacent to the first die of the third die is lower than the edge adjacent to the first die extending from the second die concave position. Edge adjacent to the first die extending from the second die concave is lower than the edge adjacent to the second die extending from the convex portion of the first die position. Therefore, in the press molding, the third die, the second die, reaches the molding bottom dead center in the order of the first die. Pressure of the first pressure member, greater than the sum of the pressure force of the second pressing member and third pressing member is disposed below the first die. Be due to the direction of the sum of the pressure force of the second pressing member and third pressing member is disposed below the first die than pressure of the first pressure member is large can not be pressed at the first die .
[0040]
　When electrically controlled, the press apparatus includes a control mechanism for governing the first die, the movement of the second die and the third die. Control mechanism, the third die, the second die, in any case to reach the molding bottom dead center in the order of the first die, from the molding bottom dead center reaches the third die to the forming bottom dead center reaches the first die during the third die is in the molding bottom dead center. Between the molding bottom dead center reaches the second die to the forming bottom dead center reaches the first die, the second die is in the molding bottom dead center.
[0041]
　In the above pressing apparatus, the curvature radius of the punch shoulder cross-section, 2 mm or more, preferably 10mm or less. The maximum bending radius of the punch shoulder, 100 mm or more, and preferably 250mm or less. The width between the punch shoulder and the recess of the punch is preferably not 15mm or less. The depth of the concave portion of the punch, 3 mm or more, preferably 20mm or less.
[0042]
　Method for producing a press-molded product according to an embodiment of the present invention comprises a first step, a second step. Press-molded product is provided with a top plate portion, and a vertical wall portion, and a ridge line portion connecting the top plate portion and the vertical wall portion. Ridge is curved on the top plate side. The top plate recesses are formed. In the first step, the recess is pressed into the blank with a punch, and the first die, the. Punch has a shape corresponding to the overall shape of the press-molded product. The first die has a shape corresponding to the shape of at least the recess. The shape corresponding to the shape of the recess, means a protrusion recess shape is inverted. Recess of the top plate portion by the convex portion of the first die is molded. In the second step, the punch, and the second die, a vertical wall portion and a ridge portion in the blank using a press-molding. The second die is disposed adjacent to the first die. The second die has a shape corresponding to the shape of at least the vertical wall portion and a ridge portion. To correspond to the shape of the vertical wall portion and the ridge portion is meant to comprise a concave shape along the shape of the vertical wall portion and a ridge portion. The first step is terminated after the second step.
[0043]
　When viewed in cross section perpendicular to the ridge of the press molded article, when manufacturing a press molded article having a vertical wall portion on one side only, it can be applied production method as follows.
[0044]
　Method for producing a press-molded product according to an embodiment of the present invention comprises a first step, a second step. Press-molded product is provided with a top plate portion, and a vertical wall portion, and a ridge line portion connecting the top plate portion and the vertical wall portion. Ridge is curved on the top plate side. The top plate, the recess having a bottom surface and the inner wall surface is formed. In the first step, at least the inner wall surface in the blank press molded with a punch, and the first die, the. Punch has a shape corresponding to the overall shape of the press-molded product. The first die has a shape corresponding to the shape of the inner wall of at least the recess. In the second step, the punch, and the second die, a vertical wall portion and a ridge portion in the blank using a press-molding. The second die is disposed adjacent to the first die. The second die has a shape corresponding to the shape of at least the vertical wall portion and a ridge portion. In the first step and second step, to sandwich the blank using the punch, and a third die, the. The third die is provided with a shape corresponding to the shape of at least a portion of the bottom surface of the recess of the press-molded product. The first step is terminated after the second step.
[0045]
　In the above manufacturing method, before the first step, as a blank, it may be prepared a blank having a shallow recess than the depth of the recess in a region corresponding to the recessed portion of the press-molded product.
[0046]
　In the above manufacturing method, the radius of curvature in the cross section of the ridge portion, 2 mm or more, preferably 10mm or less. The height of the vertical wall portion, 17 mm or more, preferably 35mm or less. Maximum curvature radius of the ridge portion, 100 mm or more, and preferably 250mm or less. Width between the ridge portion and the recess in the top plate portion is preferably not 15mm or less. The depth of the recess in the top plate portion, 3 mm or more, preferably 20mm or less.
[0047]
　The above method of preparation are particularly suitable for the production of chassis parts of a motor vehicle.
[0048]
　Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.
[0049]
　[First Embodiment]
　[press molded product]
　The press-molded product manufactured by the manufacturing method of the first embodiment will be described with reference to FIG. Press-molded product 1 includes a vertical wall 5, a top plate 4, a. Vertical wall 5 extends between the first end 2a and a second end 2b of the main body portion 2 of the main body 2 of the press-molded article 1 is curved inwardly. Top plate 4 leads through the ridge portion 6 to the vertical wall 5. The top plate 4, the recess 8 along the edge 7 adjacent the ridge portion 6 is formed. Such press-molded article 1 is applied to the lower arm. The following illustrates the case of manufacturing the lower arm shown in FIG. 1 as a press-molded product 1.
[0050]
　[Press device]
　will be described with reference to FIG. 4 for the press apparatus used in the manufacturing method of the first embodiment.
[0051]
　Figure 4 is a cross-sectional view of the pressing device of the first embodiment. Pressing device 10 is provided with a punch 13 as a lower die includes a first die 11 as an upper die and a second die 12. The punch 13, the overall shape of the lower arm 1 shown in FIG. 1 are formed. Punch 13 includes a top surface 14, a side surface 15, and a punch shoulder 16. Further, the top surface 14 also includes a region between the recess 17 and the punch shoulder 16. The top surface 14, the shape of the top plate 4 of the lower arm 1 shown in FIG. 1 are formed. That is, the top surface 14 has a recess 17. The side surface 15, the shape of the vertical wall portion 5 of the lower arm 1 shown in FIG. 1 are formed. Punch shoulder 16 connects the top surface 14 and side surface 15. The contour of the punch shoulder 16 is arcuate. Punch shoulder 16, the shape of the ridge portion 6 of the lower arm 1 shown in FIG. 1 are formed. Punch shoulder 16 is curved on the top surface 14 side. That is, the punch shoulder 16, forming a ridge portion 6 of the lower arm 1 curved inward (top plate 4 side) as shown in FIG.
[0052]
　The first die 11 faces the recess 17 of the punch 13. The first die 11 has a convex portion 18 having a shape corresponding to the recess 17 of the punch 13. That is, the shape of the convex portion 18 has a shape which the recess 17 has irregularities reversed. Strictly corresponding to the thickness of the blank, the projecting portion 18 is recess 17 smaller. In short, the first die 11, the shape of the recess 8 of the lower arm 1 at least as shown in FIG. 1 is formed.
[0053]
　The second die 12 is disposed adjacent to the first die 11. The second die 12 has a concave 19 having a shape corresponding to the punch shoulder 16 and the side surface 15 of the punch 13. That is, the shape of the concave 19 is shaped to punch shoulder 16 and the side 15 has irregularities reversed. Moreover, strictly corresponding to the thickness of the blank, the shape of the concave 19 is offset from the punch shoulder 16 and the side 15. In short, the second die 12, the shape of at least the vertical wall 5 and the ridge portion 6 of the lower arm 1 shown in FIG. 1 is formed.
[0054]
　The first die 11 and second die 12 is disposed on the lower side of the upper holder 20. Each between the first die 11 and second die 12 and the upper holder 20, the first pressing member 61 and the second pressing member 62 is provided. The first pressing member 61 and the second pressing member 62, a hydraulic cylinder, a gas cylinder, spring, rubber or the like. Upper holder 20 is attached to a slide (not shown). Punch 13 is fixed to the lower holder 21. Lower holder 21 is attached to a bolster plate (not shown). When the first pressing member 61 and the second pressing member 62 is in the unloaded condition (upper holder 20 is raised), the edge adjacent to the first die 11 extending from concave 19 of the second die 12, the It is lower than the edge adjacent to the second die 12 extending from the convex portion 18 of the first die 11 position. Therefore, it drops the upper holder 20, the second die 12 after reaching the molding bottom dead center, the first die 11 reaches the molding bottom dead center.
[0055]
　Pressing device 10 is not limited to the case shown in FIG. For modification will be described.
[0056]
　Figure 14 is a sectional view showing a modification of the press apparatus of the first embodiment. The difference from FIG. 4, the first die 11 is to the upper side of the second die 12, the second pressing member 62 at the upper side of the second die is between the first die 11 of the second die 12 it is. The second die 12 adjacent to the edge extending from the protrusion 18 of the first die 11 is arranged on the lower side of the first die 11. Also in this modification, when the first pressing member 61 and the second pressing member 62 is in the unloaded condition (upper holder 20 is raised), the first die 11 extending from concave 19 of the second die 12 adjacent edges 72 is at a position lower than the edge 71 adjacent to the second die 12 extending from the convex portion 18 of the first die 11. Therefore, it drops the upper holder 20, the second die 12 after reaching the molding bottom dead center, the first die 11 reaches the molding bottom dead center.
[0057]
　It explained another modification. Pressing device 10 is not limited to the case shown in FIG.
[0058]
　Figure 12 is a sectional view showing a modification of the press apparatus of the first embodiment. For example, the first die 11 and second die 12 may be respectively attached to the slide that moves individually. In this case, the slide is movable individually is first pressing member 61 and the second pressing member 62. Pressing device 10 further includes a control mechanism 23. Control mechanism 23 is a control computer, the first pressing member 61 and the second pressing member 62 issues an instruction, governs the movement of the first die 11 and second die 12. Control mechanism 23, to reach the second die 12 to the molding bottom dead center. Then, to reach the first die 11 to the molding bottom dead center.
[0059]
　[Production Method]
　The method for producing a lower arm 1 shown in FIG. 1 will be described with reference to the above mentioned pressing device. Manufacturing method of the first embodiment includes a preparation step, a blank positioning step, a first step and a second step. Hereinafter, the respective steps will be described.
[0060]
　[Preparation Step]
　In the preparation step, preparing a blank made of a metal plate. Blanks, for example, obtained by punching a metal plate (blanking). The metal plate, for example, steel, aluminum, an aluminum alloy or the like. If the metal plate is a steel plate, the manufacturing method of the first embodiment, the thickness t of the steel sheet, 1.8 mm or more, is particularly effective when it is 6.0mm or less. Thus blanks may be made by oneself, if the metal plate of suitable shape is sold may be blank buy it.
[0061]
　Blank arrangement step]
　In the blank positioning step, the blank prepared in the preparation step is disposed between the first die 11 and the punch 13 of the press. At this time, the end side of the blank is disposed between the second die 12 and the punch 13 of the press. End of the blank may be located between the second die 12 and the punch 13 of the press, it may protrude from between the second die 12 and the punch 13.
[0062]
　As described above, in a typical lower arm manufacturing method, in a state sandwiching the recess 106 by the first die 101 and the punch 103, the vertical wall portion 107 is formed by the second die 102 (FIGS. 2A ~ Figure 2C reference ). Specifically, when forming the vertical wall 107, the recess 106 is sandwiched between the first die 101 and the punch 103. Therefore, during the molding of the longitudinal wall portion 107, the material is less likely to flow into the recess 106 side. In such a general production method, when producing a lower arm comprising a vertical wall which is curved in a top plate portion and the inner having the recesses, fatigue resistance of the lower arm is lowered.
[0063]
　Therefore, in the manufacturing method of the first embodiment, in order to suppress a decrease in fatigue resistance of the lower arm, forming by pushing of the first die, performing press molding to end later than forming by pushing the second die .
[0064]
　First and second steps]
　FIGS 5A ~ 5C are directed to press molded article that consists as lower arm, a cross-sectional view for explaining an example of the first and second steps according to the manufacturing method of the first embodiment. Figure 5A, in the first step and the second step of the first embodiment, and shows a stage before the press molding. Figure 5B, in the first step and the second step of the first embodiment, and shows a stage during the press forming. Figure 5C, in the first step and the second step of the first embodiment, and shows the stage of press molding ends.
[0065]
　As shown in FIG. 5A, place the blank S in place of the pressing device 10. Thereafter, the slide (not shown) is lowered, first of all, the vertical wall portion 5 is formed by the second die 12 and the punch 13 (see FIG. 5B).
[0066]
　As shown in Figure 5B, when the processing of the blank S by the second die 12 is completed, the processing of the blank S by the first die 11 is not completed. Therefore, of the blank S, a region to be molded in the recess 8 of the lower arm 1, there is space SP between the punch bottom surface 13a. In this state, the slide is further lowered, and finally, the recess 8 is formed by the first die 11 (see FIG. 5C). Further, with the forming of the recess 8, the edge 7 is also formed.
[0067]
　When blank S is processed by the first die 11, minutes of the space SP exists, blank S is drawn toward the bottom surface 13a of the punch 13. In this case, the material of the blank S flows into the vertical wall 5 side into the recess 8 side (see FIG. 5C). The material into the recess 8 side flows, since the tensile force to the back side of the ridge portion 6 is loaded, the compression stress is reduced. With the reduction of compressive stresses, the restoring force of the vertical wall portion 5 is also reduced, after release, the spring-back amount of the vertical wall portion 5 is reduced. When the amount of spring back is reduced, the back side of the residual stress of the ridge portion 6, or remains in the compression direction, or even as residual stress acts in the pulling direction, a slight tensile stress, residual tensile stress is conventionally It can also be reduced. Accordingly, reduction of fatigue resistance of the lower arm 1 is prevented.
[0068]
　As shown in FIG. 5C, the machining of the blank S by the first die 11 is completed, the recess 8 is formed, the lower arm 1 shown in FIG. 1 is obtained.
[0069]
　Here, with reference to FIG. 6 will be described with the first die 11 dividing line and the second die 12.
[0070]
　Figure 6 is an enlarged cross-sectional view of a ridge portion 6 near the lower arm in FIG 5C. In the lower arm 1 of the first embodiment, the edge line section 6 refers to the region to the boundary P1 ~ boundary P2 in FIG. Boundary P1 is the boundary between the ridge portion 6 and the vertical wall portion 5. Boundary P2 is the boundary between the ridge portion 6 and the edge 7. Boundary P1 and the boundary P2 is the outline of the ridge portion 6. Edge 7, refers to a region to the boundary P2 ~ boundary P3. Boundary P3 is a boundary between the edge 7 and the recess 8. In FIG. 6, the contour of the end portion 8a of the recess 8, a case is an arc. In this case, the boundary P3 is one of the end portions 8a.
[0071]
　The first die 11 dividing line and the second die 12 is preferably provided between the perimeter P2 ~ boundary P3. The reason for this is as follows. The first die 11 dividing line and the second die 12, if the outer side (the vertical wall portion 5 side) from the boundary P2, the end of the first die 11 becomes sharp. As a result the first die 11 is easily damaged. Also, the first die 11 dividing line and the second die 12, if also the inner (concave 8 side) of the boundary P3, when the recess 8 is formed by the first die 11, the second die 12 and the punch frictional resistance by 13 increases. When the frictional resistance of the second die 12 and the punch 13 is large, the material is less likely to flow into the 8 side recess. As a result, the end portion of the second die 12 is sharp, the second die 12 is easily damaged.
[0072]
　[Second Embodiment]
　In the first embodiment, has been described a case blank S is flat. However, the blank S is not limited to the case is a flat plate. For example, the blank S is preliminarily may be an intermediate molded article formed is decorated press forming one step or more steps in the metal plate.
[0073]
　The second embodiment is blank S to be prepared in the preparing step, different from the first embodiment in that it has a recess. Other configurations of the manufacturing method of the second embodiment is the same as the first embodiment. Hereinafter, repeated description overlapping the first embodiment as appropriate.
[0074]
　[Preparation Step]
　In the preparation process of the second embodiment has a depressed portion, preparing a blank S made of a metal plate. Depression, before the first step and second step, advance is molded by press molding the material metal sheet. Recess of the blank S in the second embodiment is shallower than the depth of the recess of a product press-molded product. As described later, the space provided between the blank S and the punch bottom surface, in order to flow the material at the time of molding the recess.
[0075]
　FIGS 7A ~ 7C are directed to press molded article that consists as lower arm, a cross-sectional view for explaining an example of the first step and second step according to the production method of the second embodiment. FIG. 7A, in the first step and the second step of the second embodiment, showing the stage before the press molding. Figure 7B, in the first step and the second step of the second embodiment, showing the steps in press molding. Figure 7C, in the first step and the second step of the second embodiment, showing the steps in press molding ends.
[0076]
　As shown in FIG. 7A, in the second embodiment, the blank S is prepared in the preparing step has a recess 9a. Recess 9a is provided in a region corresponding to the recessed portion 8 of the lower arm 1. The depth of the recess 9a is shallower than the depth of the recess 8. Recess 9a is formed in the recess 8 by the first die 11 and the punch 13. In this case, in the first step and second step, forming amount of the blank S by the first die 11 is small. Therefore, defects such as cracks in the concave portion 8 of the lower arm 1 which is molded is less likely to occur. Even in this case, as shown in FIG. 7B, when the molding of the second die 12 is completed, the space SP is provided between the recess 9a and the punch bottom surface 13a of the blank S. While the first die 11 is machined blank S, in order to flow the material from the vertical wall portion 5 side to the recess 8 side (see Fig. 7C).
[0077]
　Figure 8 is that in FIG. 7A ~ 7C, a cross-sectional view showing an example of the first and second steps of the second embodiment using the different blanks. Figure 8 illustrates the step of press-molding of the second die has been completed. Blank S shown in FIG. 8 includes a raised portion 9b instead of the recess 9a. Ridges 9b are provided in the region corresponding to the recessed portion 8 of the lower arm 1. The height of the raised portion 9b is lower than the depth of the recess 8. Ridges 9b are formed in the recess 8 by the first die 11 and the punch 13. Even in this case, the space SP is provided between the ridges 9b and the punch bottom surface 13a of the blank S. Therefore, as in the case of the recess 9a, after release, the spring-back amount of the vertical wall portion 5 is reduced, and the decrease in the fatigue resistance of the lower arm 1 is prevented. The height of the depth and the raised portion 9b of the concavity 9a is the strength of the material, plate thickness is appropriately set in consideration of the ductility and the like.
[0078]
　[Third Embodiment]
　The third embodiment is basically the first embodiment. However, in the third embodiment in that the press-molded product having a vertical wall portion only one side is different from the first embodiment. Also, for producing such a press-molded product further to the press apparatus of the first embodiment, also that the third die is added differs from the first embodiment. Press-molded product produced by the process of the pressing device and manufacturing the third embodiment, for example, the reinforcing member (reinforcement) of the lower arm, a vehicle body frame component of an automobile. Hereinafter, a press molded article is a reinforcing member of the lower arm (hereinafter, simply referred to as "reinforcing member") describing the case where the.
[0079]
　[Press-molded article]
　reinforcing member manufactured by the manufacturing method of the third embodiment has only vertical wall portion 5a of the lower arm 1 shown in FIG. In other words, there is no vertical wall portion 5b and 5c of the lower arm 1 shown in FIG. Other configurations of the reinforcing member is the same as the lower arm 1 of the first embodiment. That is, as lower arm reinforcing member of the third embodiment is also shown in FIG. 1, it has a vertical wall portion and a ridge portion is curved inward. Reinforcing member of the third embodiment, for example, attached to the back side of the lower arm shown in FIG. The reinforcing member reinforces the ridge portion 6 near to the curvature of the lower arm shown in FIG. When producing such a reinforcing member in the conventional manufacturing method, similar to the lower arm as described above, the fatigue resistance of the reinforcing member tends to decrease.
[0080]
　[Press device]
　will be described with reference to FIG. 9 for the press apparatus used in the manufacturing method of the third embodiment.
[0081]
　Figure 9 is a cross-sectional view of a press apparatus according to the third embodiment. Pressing device 30 is provided with a punch 34 as a lower die includes a first die 31 as the upper die and the second die 32 and third die 33. The punch 34, the whole shape of the reinforcing member is formed. Punch 34 includes a top surface 35, a side surface 36, and a punch shoulder 37. The top surface 35, the shape of the top plate portion of the reinforcing member is formed. Sides 36, the shape of the vertical wall portion of the reinforcing member is formed. Punch shoulder 37 connects the top surface 35 and side surface 36. The contour of the punch shoulder 37 is arcuate. Punch shoulder 37, the shape of the ridge line portion of the reinforcing member is formed. Punch shoulder 37 is curved on the top surface 35 side along the extending direction of the punch 34 (the longitudinal direction of the reinforcing member). Thus, the ridge line portion of the reinforcing member molded is curved inward (top plate side).
[0082]
　Figure 10 is an enlarged view of a punch shoulder near in FIG. Here, the side surface 36 refers to the region to the boundary P4 ~ boundary P5. Boundary P4 indicates the lower end of the side surface 36 of the punch 34. Boundary P5 is a boundary between the side surface 36 and the punch shoulder 37 of the punch 34. Indicating the end of the contour of the punch shoulder 37. Boundary P6 is the boundary between the punch shoulder 37 and the top surface 35. Punch shoulder 37 is an area to the boundary P5 ~ boundary P6. Boundary P5 and border P6 is the contour of the punch shoulder 37. Top surface 35 shows a region of the third die side from the boundary P6 (left side in FIG. 10).
[0083]
　Top surface 35 includes a flat portion 35a and the recess 35b. Flat portion 35a is a region of the boundary P6 ~ boundary P7. Boundary P7 is the boundary between the flat portion 35a and the recess 35b. Furthermore recess 35b has an inner wall surface 40 and bottom surface 39. The inner wall surface 40 is an area to the boundary P7 ~ P8. Contour of the end portions of the inner wall surface 40 is arcuate. That is, the boundary P7 and P8 is an end of the inner wall surface 40. The boundary P8 is a boundary between the inner wall surface 40 and bottom surface 39. The bottom surface of the concave portion 35b 39 is the area to the edge of the boundary P8 ~ punch 34.
[0084]
　The first die 31 is opposed at least the inner wall surface 40 and the pressing direction of the recess 35b of the punch 34. The first die 31 has a convex portion 41 having a shape corresponding to the inner wall surface 40 of the recess 35b of the punch 34. In other words, the first die 31 has a convex portion 41 which recesses 35b and irregularities are inverted punch 34. That is, the first die 31, the shape of the inner wall surface 8c of at least the reinforcing member (see FIG. 1) are formed. Here, the first die 31 may be opposed to the flat portion 35a and the pressing direction of the punch 34. The first die 31 is not opposed to the press direction to the punch shoulder 37. As described above, the end portion of the first die 31 is because the result fragile sharpened. The first die 31 may be opposed to the bottom surface 39 and the pressing direction of the punch 34. However, the first die 31 is not opposed to the pressing direction and the entire region of the bottom surface 39 of the punch 34. The third die 33 to be described later is to leave a region sandwiching the blank S.
[0085]
　The second die 32 is similar to the second die 12 of the first embodiment (see FIG. 4). That is, the second die 32 is disposed adjacent to the first die 31. The second die 32 has a concave 42 having a shape corresponding to the punch shoulder 37 and the side surface 36 of the punch 34. In other words, the second die 32 is provided with a concave 42 having a shape irregularity of the punch shoulder 37 and the side surface 36 of the punch 34 is inverted. That is, the second die 32, the shape of the vertical wall 5 and the ridge portion 6 of the at least reinforcing member (see FIG. 1) are formed.
[0086]
　As shown in FIG. 9, the third die 33 is disposed adjacent to the first die 31. The third die 33, the second die 32 across the first die 31 is arranged on the opposite side. The third die 33, the shape corresponding to the shape of at least a portion of the bottom surface of the concave portion of the reinforcing member is formed. The third die 33 is opposed to the bottom surface 39 of the punch 34. Region third die 33 faces the bottom surface 39 of the punch 34 is not particularly limited. Region third die 33 faces the bottom surface 39 of the punch 34 is appropriately set by the size of the first die 31. However, the third die 33 is not opposed to the press direction to the inner wall surface 40 of the punch 34. As described above, the inner wall surface of the punch 34 is opposed to the first die 31 and the press direction. Thus, the first die 31 is because it is possible to flow the material of the blank during the press forming.
[0087]
　The first die 31, the second die 32 and third die 33 is disposed on the lower side of the upper holder 43. The first die 31, respectively between the second die 32 and third die 33 and the upper holder 43, the first pressing member 61, the second pressing member 62 and the third pressing member 63 is provided. Upper holder 43 is attached to a slide (not shown). Punch 34 is fixed to the lower holder 44. Lower holder 44 is attached to a bolster plate (not shown) as in the first embodiment.
[0088]
　The first pressing member 61, when the second pressing member 62 and the third pressing member 63 is in the unloaded condition (upper holder 43 is raised), punch 34 adjacent to the first die 31 of the third die 33 side edge 73 is at a position lower than the edge 72 adjacent to the first die 31 extending from concave 42 of the second die 32. Difference in height between the edge each other, is greater than the difference in height between the bottom surface 39 of the flat portion 35a and the punch 34 of the punch 34. The first pressing member 61, when the second pressing member 62 and the third pressing member 63 is in the unloaded condition (upper holder 43 is raised), the first die 31 extending from concave 42 of the second die 32 adjacent the edge 72 is at a position lower than the adjacent edge 71 and the second die 32 extending from the protrusion 41 of the first die 31. Therefore, the upper holder 43 is lowered, the third die 33, the second die 32 reaches the molding bottom dead center in the order of the first die 31.
[0089]
　Pressing device 30 is not limited to the case shown in FIG. For modification will be described.
[0090]
　Figure 15 is a sectional view showing a modification of the press apparatus of the third embodiment. The difference from FIG. 9, the first die 31 is to the upper side of the second die 32, the second pressing member 62 at the upper side of the second die 32, between the first die 31 of the second die 32 is that there. The second die 32 is adjacent the edge 71 extending from the protrusion 41 of the first die 31 is arranged on the lower side of the first die 41. Also in this modification, the first pressure member 61, when the second pressing member 62 and the third pressing member 63 is in the unloaded condition (upper holder 43 is raised), the first die of the third die 33 punch 34 side edge 73 adjacent to 31 is in a position lower than the edge 72 adjacent to the first die 31 extending from concave 42 of the second die 32. Difference in height between the edge each other, is greater than the difference in height between the bottom surface 39 of the flat portion 35a and the punch 34 of the punch 34. The first pressing member 61, when the second pressing member 62 and the third pressing member 63 is in the unloaded condition (upper holder 43 is raised), the first die 31 extending from concave 42 of the second die 32 adjacent the edge 72 is at a position lower than the adjacent edge 71 and the second die 32 extending from the protrusion 41 of the first die 31. Therefore, the upper holder 43 is lowered, the third die 33, the second die 32 reaches the molding bottom dead center in the order of the first die 31.
[0091]
　Figure 16 is a sectional view showing a modification of the press apparatus of the third embodiment. As another example, as shown in FIG. 16, the first die 31 is to the upper of the third die 33, a third pressing member 63 at the upper side of the third die 33 includes a first die 31 third die it may be between 33.
[0092]
　It explained another modification. Pressing device 30 is not limited to the case shown in FIG.
[0093]
　Figure 13 is a sectional view showing a modification of the press apparatus of the third embodiment. For example, the first die 31, the second die 32 and third die 33 may be respectively attached to the slide that moves individually. In this case, the slide is movable individually first pressure member 61, a second pressure member 62 and the third pressing member 63. Pressing device 30 further includes a control mechanism 24. Control mechanism 24 is responsible for the movement of the first die 31, the second die 32 and third die 33. Controller instructs to reach the third die 33, the molding bottom dead center in the order of the second die 32 first die 31. The first pressing member 61, the second pressing member 62 and the third pressing member 63 receives the instruction from the control mechanism 24, the first die, moving the second die and the third die.
[0094]
　[Production Method]
　describes a method for producing a reinforcing member with a pressing device of the third embodiment. Manufacturing method of the third embodiment, a basic manufacturing method of the first embodiment. Manufacturing method of the third embodiment, in a state of pressing down the blanks in the third die in the first step and second step, different from the first embodiment in that carrying out the press-molding by the first die and the second die to. Preparing step in the manufacturing method of the third embodiment is the same as the first embodiment description is omitted. The following describes the first step and the second step of the manufacturing method of the third embodiment.
[0095]
　[First step and the second step]
　In the third embodiment, in a cross-sectional view as described above, to produce a reinforcing member having a vertical wall portion on only one side. Thus, the second die for forming a vertical wall portion is disposed only on one side. Doing press molding in such a press apparatus, when the second die press molding a blank, the blank is not constrained. Therefore, the second die may blank moves during press molding, easily stabilized conducted press molding. Therefore, in the third embodiment, to add a third die to the press apparatus of the first embodiment. Then, while restraining the blank by the third die, the blank press-molded in the same manner as the first embodiment by the first die and second die, to produce a reinforcing member. Thus, when manufacturing a reinforcing member having a vertical wall portion on one side only, it can be stably carried out press molding. The first die can be made to flow the material of the blank during the press molding, a decrease in fatigue resistance of the molded reinforcing member can be suppressed.
[0096]
　Figure 11A ~ FIG. 11C is a cross-sectional view illustrating an example of a third first step by the manufacturing method of the embodiment and the second step. Figure 11A, in the first step and the second step of the third embodiment and showing the stage before machining. Figure 11B, in the first step and the second step of the third embodiment, showing a stage during processing. Figure 11C, in the first step and the second step of the third embodiment and illustrating a stage of the processing end.
[0097]
　As shown in FIG. 11A, after placing the blank S in place of the pressing device 30, a slide (not shown) is lowered, first clamp the blank S by the third die 33 and the punch 34. Here, when sandwiching the blank S, it may be molded blank S by the third die 33 and the punch 34.
[0098]
　As shown in FIG. 11B, in a state of being restrained by the third die 33, the blank S is press-molded by the second die 32 and the punch 34. Like the first embodiment, when the machining of the blank S by the second die 32 is completed, the processing of the blank S by the first die 31 is not completed. In this state, the slide is further lowered, and finally, the recess 51 of the reinforcing member 50 is molded by the first die 31 (see FIG. 11C). Further, with the forming of the recess 51, the edge 52 is also formed. Thus, similarly to the first embodiment in the third embodiment, after the release, the spring-back amount of the vertical wall portion is reduced, and the decrease in the fatigue resistance of the reinforcing member 50 is suppressed.
[0099]
　It has been described above method for producing a reinforcing member of the lower arm of the third embodiment.
[0100]
　Hereinafter, a preferred embodiment of the press device of the first to third embodiments described above.
[0101]
　[Curvature radius of the punch shoulder]
　radius of curvature in the cross section of the punch shoulder 16, 2 mm or more, preferably not more than 10 mm. Here, the cross section of the punch shoulder 16, refers to a cross section perpendicular to the extending direction of the punch shoulder 16 as shown in FIG. 4 (extending direction of the lower arm). If it is less than the radius of curvature of the punch shoulder 16 2 mm, during press molding, a vertical wall portion which is the second die 12 thus formed is bent sharply. Therefore, when the recess of the lower arm by the first die 11 is molded, hard material flows into the concave side from the vertical wall portion. If the radius of curvature of the punch shoulder 16 is greater than 10 mm, the radius of curvature of the ridge line portion of the lower arm which is molded is increased. Thus, since the second moment of the lower arm is small, the strength of the lower arm 1 becomes insufficient.
[0102]
　Maximum curvature radius of the punch shoulder]
　As shown in FIG. 1, the vertical wall portion 5 of the lower arm 1 of this embodiment is curved inwardly. As described above, the vertical wall portion 5 is processed by stretch flangeability. The ridge portion 6 leading to the vertical wall 5 is curved. The smaller radius of curvature of the ridge line portion 6, the residual tensile stress occurs on the back side of the ridge portion 6 of the lower arm 1 which is molded becomes large, the fatigue resistance of the lower arm 1 tends to decrease.
[0103]
　Ridge portion 6 is formed with the punch shoulder 16 of the punch 13 by the second die 12. Like the shape of the punch shoulder 16 also ridge portion 6 of the punch 13 is curved inward (top side). The maximum bending radius of the punch shoulder 16 of the curved, 100 mm or more, and preferably 250mm or less. The reason for this is as follows. If the maximum curvature radius is less than 100mm punch shoulder 16, since the ridge portion 6 and the vertical wall portion 5 is formed to bend sharply inward, the residual tensile stress in the direction along the ridge portion 6 tends to increase. If the maximum curvature radius of the punch shoulder 16 is greater than 250 mm, the location of the suspension member of an automobile is limited, the design freedom is reduced. The maximum curvature radius of the punch shoulder 16, when the curvature radius of the punch shoulder 16 is different depending on the position refers to the maximum radius of curvature of them.
[0104]
　Width between the punch shoulder and the recess of the punch]
　will be described with reference by way of example to the press apparatus of the third embodiment shown in FIG. 10 the width between the punch shoulder and the recess of the punch. The following limitations on the width between the recess 35b of the punch shoulder 37 and the punch 34 is also applicable to the press apparatus of the first and second embodiments.
[0105]
　Width between the recess 35b of the punch shoulder 37 and the punch 34 is preferably not 15mm or less. Width between the recess 35b of the punch shoulder 37 and the punch 34, refers to the distance between the boundary P6 and the boundary P7 shown in FIG. 10. If the width between the recess 35b of the punch shoulder 37 and the punch 34 is larger than 15 mm, the frictional resistance of the second die 32 and the punch 34 becomes large. Therefore, according to the first die 31 (not shown) by a molding recess of the press-molded product, the material is less likely to flow into the concave side of the press-molded product. The lower limit of the width between the recess 35b of the punch shoulder 37 and the punch 34 is not particularly limited. Width between the recess 35b of the punch shoulder 37 and punch 34 may be zero. In this case, it leads to smooth the recess 35b of the punch shoulder 37 and the punch 34.
[0106]
　Depth of the recess of the punch]
　will be described with reference by way of example to the press apparatus of the third embodiment shown in FIG. 10 for the depth of the concave portion of the punch. Limitations on the depth of the recess 35b below the punch 34 is also applicable to the press apparatus of the first and second embodiments.
[0107]
　The depth of the recess 35b of the punch 34, 3 mm or more, preferably 20mm or less. The depth of the recess 35b of the punch 34, refers to the distance to the bottom surface 39 of the recess 35b from the flat portion 35a of the punch 34 shown in FIG. 10. Is less than 3mm in depth of the concave portion 35b of the punch 34, the inflow of material into the concave side of the press-molded product according molding (not shown) of the press-molded product recess is performed by the first die 31 is not sufficient. If the depth of the concave portion 35b of the punch 34 is larger than 20 mm, for forming amount by the first die 31 is large, the blank tends to crack.
[0108]
　Hereinafter, a preferred embodiment of the first to third embodiments a method of press-molded products produced as described above.
[0109]
　[Curvature radius of the ridge portion]
　As shown in FIG. 6, the contour of the ridge portion 6 of the lower arm is a circular arc. Radius of curvature in the cross section of the ridge portion 6, 2 mm or more, preferably not more than 10 mm. Here, the cross section of the ridge portion 6 refers to a cross section perpendicular to the extending direction of the lower arm 1 in the ridge portion 6. If it is less than the radius of curvature of the ridge portion 6 is 2 mm, since the vertical wall 5 is bent abruptly, when the recess 8 by the first die 11 is molded, the material flows into the recess 8 side from the vertical wall portion 5 Hateful. If the radius of curvature of the ridge portion 6 is larger than 10 mm, since the second moment of the lower arm is small, the strength of the lower arm 1 becomes insufficient.
[0110]
　Height of the vertical wall portion]
　shown in FIG. 6, the height h of the vertical wall portion 5, 17 mm or more, preferably 35mm or less. The height h of the vertical wall portion 5 refers to the distance between the end of the edge 7 and the vertical wall portion 5. If the height h is less than 17mm of the vertical wall portion 5, since the second moment of the lower arm 1 is small, the strength of the lower arm 1 becomes insufficient. If it is greater than 35mm height of the vertical wall portion 5, since the frictional resistance of the second die 12 and the punch 13 is large, when the recess 8 is formed by the first die 11, material from the vertical wall portion 5 less likely to flow into the recess 8 side.
[0111]
　Maximum curvature radius of the ridge portion]
　As shown in FIG. 1, the ridge line portion 6 of the lower arm 1 of this embodiment is curved inwardly. The smaller radius of curvature of the ridge line portion 6, the residual tensile stress occurs on the back side of the ridge portion 6 of the lower arm 1 which is molded becomes large, the fatigue resistance of the lower arm 1 tends to decrease. Maximum curvature radius of the ridge portion 6 to the curved, 100 mm or more, and preferably 250mm or less. The reason for this is as follows. If the maximum curvature radius is less than 100mm ridge portion 6, since the ridge portion 6 is curved sharply inward, the residual tensile stress in the direction along the ridge portion 6 tends to increase. If the maximum curvature radius of the ridge portion 6 is larger than 250 mm, the location of the suspension member of an automobile is limited, the design freedom is reduced. The maximum curvature radius of the ridge portion 6 refers to a curvature radius of the ridge portion 6, when the curvature radius of the ridge portion 6 is different from the position refers to the maximum radius of curvature of them.
[0112]
　Width of the edge]
　width W of the edge 7 is preferably not 15mm or less. Width W of the edge 7, as shown in FIG. 6 refers to the distance between the boundary P2 and the boundary P3. If the width W of the edge 7 is greater than 15 mm, the frictional resistance of the second die 12 and the punch 13 becomes large. Therefore, the first die 11 when the concave portion 8 is formed, the material is less likely to flow into the 8 side recess. The lower limit of the width W of the edge 7 is not particularly limited. Width W of the edge 7 may be 0. In this case, the end portion 8a of the ridge portion 6 and the recess 8 are smoothly connected to.
[0113]
　Depth of the recess]
　the depth D of the recess 8, 3 mm or more, preferably 20mm or less. The depth D of the recess 8, as shown in FIG. 6 refers to the distance to the bottom surface 8b of the recessed portion 8 from the edge 7. If it is less than the depth D is 3mm recess 8, when being molded recess 8 by the first die 11, the inflow of material into the recess 8 side is not sufficient. If the depth D of the recess 8 is greater than 20 mm, for forming amount by the first die 11 is large, blank S is easily broken.
[0114]
　In the above, the press-molded product manufactured by the manufacturing method of this embodiment has been described a case where a lower arm for a motor vehicle. However, the press-molded product is not limited to the lower arm. The manufacturing method of this embodiment includes a vertical wall which is curved in the concave portion and the inner, which is effective for the production of a press molded article is required excellent fatigue resistance. Such press-molded article, for example, an underbody part of an automobile. Underbody parts, in addition to the lower arm, there is an upper arm or the like.
[0115]
　Pressing device 10 of the present embodiment has a first die 11 and second die 12 as an upper mold, showing a case where a punch 13 as a lower die. However, these arrangements are not particularly limited. That is, the press apparatus 10 includes a first die 11 and second die 12, the arrangement of the punch 13 may be vertically reversed. In short, the first die 11 and second die 12 may have a configuration to move relative to the punch 13.
Example
[0116]
　In order to confirm the effect of the present invention, tests were carried out following by FEM analysis. The FEM analysis, by pressing a material metal sheet, assuming that the production of press-formed product that holds the lower arm. As the present invention example, assuming the manufacturing method of the second embodiment shown in FIGS. 7A ~ Figure 7C. As a comparative example, assuming a general manufacturing method shown in FIGS. 2A ~ Figure 2C. Namely, the inventive examples, molding by the first die 11 is different from the comparative example in that the ends later than forming by the second die 12. Further, in the present invention example while the blank S has a recess 9a, in the comparative example differs in that it has a recess 106 which blank S is preformed. The other conditions were the same in the comparative example and the present invention embodiment. In press-molded product produced by the production method were evaluated residual stress of the stress and the release after the press-molded product is loaded on the ridge line portion of the press-molded product in the molding bottom dead center.
[0117]
　In the present invention examples and comparative examples were produced the shape of the press-molded product shown in FIG. Material metal plate, a plate thickness of 2.6mm, tensile strength was a steel plate of 980MPa. The radius of curvature of the ridge line portion of the molded press molded article was 8 mm. The height of the vertical wall portion of the molded press molded article was 23 mm. Maximum curvature radius of the ridge portion of the molded press-formed article was 160 mm.
[0118]
　[Analysis Result]
　In the present invention embodiment, a stress tensile stress exerted on the edge line portion after the release, the maximum value was 50 MPa.
[0119]
　In Comparative Example, a stress tensile stress exerted on the edge line portion after the release, the maximum value was 340 MPa.
[0120]
　Consequently, according to the manufacturing method of this embodiment, the residual tensile stress in the ridge line portion of the press-molded article after molding can be reduced, it revealed that it is possible to suppress a decrease in fatigue resistance of the press-molded product.
Industrial Applicability
[0121]
　The method of press-molded article produced the present invention is useful for the manufacture of the press-molded product having a shape conforming to an automotive lower arm. In particular, the production method of the present invention are useful in the manufacture of the lower arm having an excellent fatigue resistance.
DESCRIPTION OF SYMBOLS
[0122]
　1: press-formed product (lower arm), 2: main body, 3: protruding portion, 5: vertical wall, 6: ridge portion, 7: edge, 8: recess, 9a: depression, 9b: ridges, 10 , 30: press apparatus, 11 and 31: the first die, 12, 32: second die, 33: third die, 13, 34: a punch, 13a: punch bottom, 14: punch top surface 15: punch side, 16: punch shoulder, 17: recess of the punch, 18: convex portion of the first die, 19: second die concave, 20: upper holder 21: lower holder 61: the first pressing member, 62: second 2 pressure member, 63: third pressure members, B: vehicle body, WH: wheel side, D: recess depth, h: vertical wall of height, W: the edge of the width, S: blank, SP: the space between the blank and the punch

WE CLAIM

A top surface, a side surface, anda punch shoulder connecting the said side and the top surface, the punch shoulder is curved on the top side, and a punch having a concave portion formed on the top surface,
　the punch are oppositely disposed in the recess, a first die having a convex portion having a shape corresponding to the recess,
　is positioned next to the first die, concave shape corresponding to the punch shoulder and the side surface of the punch a second die having,
　the upper holder and the first die is disposed on the upper side of the second die,
　a first pressure member disposed between said first die and said upper holder,
　the upper holder and a second pressure member disposed between the second die and,
　edge adjacent to the first die extending from the concave shape of the second die, from the convex portion of the first die extending in a position lower than the edge adjacent to the second die, the press apparatus.
[Requested item 2]
　A pressing apparatus according to claim 1,
　a portion of the first die between said upper holders of said second pressure member is disposed, the press apparatus.
[Requested item 3]
　A top surface, a side surface, anda punch shoulder connecting the said side and the top surface, the punch shoulder is curved on the top side, and a punch having a concave portion formed on the top surface,
　the punch are oppositely disposed in the recess, a first die having a convex portion having a shape corresponding to the recess,
　is positioned next to the first die, concave shape corresponding to the punch shoulder and the side surface of the punch a second die having,
　a first die and responsible for the movement of the second die, the control mechanism to reach the first die to the molding bottom dead center of the second die after reaching the molding bottom dead center , with a press apparatus.
[Requested item 4]
　A top surface having a side surface, and a punch shoulder connecting the said side and the top surface, the punch shoulder is curved on the top side, the recess having a bottom surface and inner wall surface to the top face forming a punch that is,
　is disposed opposite to at least the inner wall surface of the concave portion of the punch, a first die having a convex portion having a shape corresponding to the inner wall surface of the recess,
　adjacent to the first die It is disposed, and a second die having a concave shape corresponding to the punch shoulder and the side surface of the punch,
　a next of said first die, on the opposite side to the second die across the first die a third die arranged,
　the upper holder first is disposed die and said second die on the upper side of the third die,
　a first pressure which is disposed between said first die and said upper holder a member,
　and a second pressure member disposed between the second die and the upper holder,
　A third pressure member disposed between serial upper holder and said third die comprises a
　third said punch side edge adjacent to the first die die, said concave of said second die in a position lower than the edge adjacent to the first die extending from the shape,
　the edge adjacent to the first die extending from the concave shape of the second die, the second extending from the convex portion of the first die positioned lower than the edge adjacent the die, the press apparatus.
[Requested item 5]
　A pressing apparatus according to claim 4,
　a portion of the first die is disposed between at least one and the upper holder of the third pressing member and said second pressing member, the pressing device .
[Requested item 6]
　A top surface having a side surface, and a punch shoulder connecting the said side and the top surface, the punch shoulder is curved on the top side, the recess having a bottom surface and inner wall surface to the top face forming a punch that is,
　is disposed opposite to at least the inner wall surface of the concave portion of the punch, a first die having a convex portion having a shape corresponding to the inner wall surface of the recess,
　adjacent to the first die It is disposed, and a second die having a concave shape corresponding to the punch shoulder and the side surface of the punch,
　a next of said first die, on the opposite side to the second die across the first die a third die disposed,
　the first die, the second die and responsible for the movement of said third die, said third after reaching the die to the molding bottom dead center, molding bottom dead center the second die to reach the point, Bei and control mechanism, a to subsequently reach the first die to the molding bottom dead center It was, the press apparatus.
[Requested item 7]
　A press apparatus according to any one of claims 1 to 6,
　the radius of curvature in the cross section of the punch shoulder is, 2 mm or more and 10mm or less, the press apparatus.
[Requested item 8]
　A press apparatus according to any one of claims 1 to 7,
　the maximum bending radius of the punch shoulder is, 100 mm or more and 250mm or less, the press apparatus.
[Requested item 9]
　A press apparatus according to any one of claims 1 to 8,
　the width between the punch shoulder and the recess of the punch is 15mm or less, the press apparatus.
[Requested item 10]
　A press apparatus according to any one of claims 1 to 9,
　the depth of the recess of the punch, 3 mm or more and 20mm or less, the press apparatus.
[Requested item 11]
　A method of manufacturing a press molded article,
　the press molded article, a top plate portion, and a vertical wall portion, provided with a ridge portion connecting the said top plate portion and the vertical wall portion, the ridge portion includes the top plate curved section side, the recess in the top plate portion is formed,
　the manufacturing method,
　a punch having a shape corresponding to the overall shape of the press-with a shape corresponding to the shape of at least the recess a first step of press-forming the recess in the blank with a first die, a
　said punch, said first be placed next to the die at least the vertical wall portion and a shape corresponding to the shape of the ridge portion and a second step of press-forming the vertical wall portion and the ridge portion to said blank with a second die with,
　the first step is terminated after the second step, a press manufacturing method of a molded article.
[Requested item 12]
　A method of manufacturing a press molded article,
　the press molded article, a top plate portion, and a vertical wall portion, provided with a ridge portion connecting the said top plate portion and the vertical wall portion, the ridge portion includes the top plate curved section side, said recess having a bottom surface and the inner wall surface to the top plate portion is formed,
　the manufacturing method,
　a punch having a shape corresponding to the overall shape of the press-said at least said recess a first die having a shape corresponding to the shape of the inner wall surface, a first step of press-forming at least the inner wall surface to the blank using,
　the punch and, arranged next to the first die at least the longitudinal and a second step of press-forming the vertical wall portion and the ridge portion to the blank using a second die having a shape corresponding to the shape of the wall portion and the ridge portion,
　the first step and wherein in the second step, and the punch, the press Sandwiching the blank by using a third die having a shape corresponding to the shape of at least a portion of the bottom surface of the recess of the shaped piece, wherein the first step is terminated after the second step, manufacturing method of the press-molded product.
[Requested item 13]
　A method of press-molded product produced according to claim 11 or claim 12,
　wherein the blank has a shallow recess than the depth of the recess in a region corresponding to the concave portion of the press-press molding method of manufacturing the goods.
[Requested item 14]
　A claims 11 to any method of manufacturing a press molded article according to one of claims 13,
　the radius of curvature in the cross section of the ridge portion, 2 mm or more and 10mm or less, the manufacturing method of the press-molded product.
[Requested item 15]
　A claims 11 to any one method of the press-molded product produced according to claim 14,
　the height of the vertical wall portion, 17 mm or more and 35mm or less, the manufacturing method of the press-molded product.
[Requested item 16]
　A claims 11 to claim 15 The method of any of the press-molded product produced according to one of,
　the maximum curvature radius of the ridge portion, 100 mm or more and 250mm or less, the manufacturing method of the press-molded product.
[Requested item 17]
　A claims 11 to any one method of the press-molded product produced according to claim 16,
　the width between the ridge portion and the recess in the top plate portion is 15mm or less, press molding method of manufacturing the goods.
[Requested item 18]
　A claims 11 to method of the press-molded product produced according to any one of claims 17,
　the depth of the recess in the top plate portion, 3 mm or more and 20mm or less, of the press-molded product manufacturing Method.
[Requested item 19]
　A claims 11 to method of the press-molded product produced according to any one of claims 18,
　wherein the press molded product is a suspension parts of automobiles, the manufacturing method of the press-molded product.