Hot press device, method for manufacturing hot press molded article, and hot press molded article

Abstract

The invention relates to a hot press apparatus, a method for manufacturing a hot press molded article, and a hot press molded article. A hot press device (1000) is provided with a punch (1200), a die (1300), and a die pad (1100), and is characterized in that the top surface (1210) of the punch (1200) has a groove (1220), the angle between the wall surface of the groove (1220) and the press direction (P) is 2-8 DEG in a cross-section along the press direction (P), and the punch (1200) has a refrigerant flow path inside the punch (1200). The die (1300) and the die pad (1100) are disposed so as to face the punch (1200) in the pressing direction (P), the die pad (1100) is disposed so as to face the top surface (1210) of the punch (1200), the die pad (1100) has a convex portion (1120) at a position facing the groove portion (1220) in the pressing direction (P), and the convex portion (1120) has a shape in which the groove portion (1220) is inverted.

Description

Technical Field

[0001] The present invention relates to a hot pressing device, a method for manufacturing a hot pressing molded product, and a hot pressing molded product.

[0002] This application claims priority based on Tokugan Application No. 2022-085778 filed in Japan on May 26, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] Conventionally, as a frame component of an automobile, a component obtained by processing a metal plate-like component into a predetermined cross-sectional shape is used. When a product having a frame component is subjected to an impact caused by a collision, the frame component is required to achieve a desired deformation mode and effectively absorb the impact. For example, Patent Document 1 discloses a reinforcement for a bumper, which is provided with a small recess and a large recess surrounding the small recess for the purpose of increasing a peak load or increasing an amount of energy absorption.

[0004] Such frame components are required to be lightweight and have sufficient load resistance. In addition, in recent years, with the tightening of collision safety standards and fuel consumption restrictions for vehicles such as automobiles, high-strength and lightweight components are required. In order to meet such requirements, lightweight frame components using so-called high-strength materials with high tensile strength are being developed.

[0005] Patent document 2 discloses a technique for stamping a plate into a molded product having a cap shape with concave and convex shapes on the top surface. However, when the concave and convex shapes of the top surface of the molded product and the shoulder portion adjacent to the top surface are molded at the same time, these moldings interfere with each other and are difficult to mold. In patent document 2, the concave and convex shapes of the top surface of the molded product are molded in advance, and after the concave and convex shapes are constrained by the punch and the die pad, the shoulder portion of the molded product is molded by the punch and the die. Thus, the key point of patent document 2 is not to perform the two moldings at the same time.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent No. 5329188

[0009] Patent Document 2: Japanese Patent Application Publication No. 2020-075275 Summary of the invention

[0010] Problems to be solved by the invention

[0011] In the case of forming a hat-shaped molded product or a groove-shaped component having a groove on the top surface by hot pressing, if the method of Patent Document 2 is applied to hot pressing, hot pressing is performed twice. In the case of forming by one hot pressing, it can be considered to form the groove portion by the die pad and the punch on the heated sheet, and then form the shoulder portion by the punch and the die. However, in such a case, there are two problems. First, in the case where the groove portion is formed by a spring as in Patent Document 2, since the force of the spring is weak, the die pad cannot reach the bottom forming point and the groove portion cannot be formed into the desired shape (the shape of the groove portion along the top of the punch). Second, even if the die presses the die pad to make it reach the bottom forming point, a local reduction in plate thickness will occur in the groove portion of the molded product. During the period from the die reaching the bottom forming point to the die reaching the bottom forming point, the workpiece between the groove portion at the top of the punch and the die pad is in uneven contact with the die, so the workpiece has uneven temperature. The reason for the reduction in plate thickness is that when the die and the die pad reach the bottom of the forming process, the local softened portion caused by the temperature difference of the workpiece is stretched in advance.

[0012] The present invention is completed in view of the above situation. The subject of the present invention is to provide a hot press device capable of suppressing the reduction of plate thickness and necking of a concave portion of a hot press-formed product formed by a die pad, a method for manufacturing a hot press-formed product using the device, and a hot press-formed product in which the reduction of plate thickness and necking of a concave portion of a stamping-formed product is suppressed.

[0013] Means for solving problems

[0014] (1) A hot press device according to one embodiment of the present invention is characterized in that:

[0015] The hot pressing device comprises a punch, a die and a die pad.

[0016] The top surface of the punch has a groove.

[0017] In the cross section along the punching direction, the angle between the wall surface of the groove and the punching direction is 2 to 8 degrees.

[0018] The punch has a refrigerant flow path inside.

[0019] The die and the die pad are arranged to face the punch in the punching direction.

[0020] The die pad is disposed facing the top surface of the punch.

[0021] The die pad has a convex portion at a position facing the groove portion in the punching direction, and the convex portion has a shape that is an inversion of the groove portion.

[0022] (2) In the hot pressing device of (1) above, it is also possible to:

[0023] The punching die has a step portion that contacts the punching die pad in the punching direction.

[0024] At the point of forming, the die pad contacts the die in the punching direction.

[0025] (3) In the hot pressing device of (1) or (2) above,

[0026] In the cross section, an angle formed by a straight line connecting an R end of a side ridge line portion and an R end of a bottom ridge line portion of a wall surface of the groove portion and the punching direction is 2 to 8 degrees.

[0027] (4) A method for producing a hot press molded product according to one embodiment of the present invention uses the hot press apparatus described in any one of (1) to (3), characterized by comprising:

[0028] Disposing a blank between the die and the punch;

[0029] Clamping the blank by the punch and the die pad; and

[0030] The punch and the die are brought close to each other in the stamping direction until the forming point is reached.

[0031] (5) A hot press formed article according to one embodiment of the present invention comprises a first plate portion having a recessed portion and a second plate portion inclined relative to the first plate portion, wherein:

[0032] In a cross-sectional view of a plane passing through a point where the depth of the recess is the deepest and where the length of the section line of the recess is the shortest, an angle formed between a side portion of the recess and a direction perpendicular to the plate surface of the first plate portion is 2 to 8 degrees.

[0033] The plate thickness of a portion of the recessed portion where the plate thickness is smallest is 60% or more of the plate thickness of a portion of the first plate portion other than the recessed portion.

[0034] (6) In the hot press molded product of (5) above,

[0035] In the cross-sectional view, an angle formed by a straight line connecting the R end of the side ridge line portion of the side portion of the recess and the R end of the bottom ridge line portion and a direction perpendicular to the plate surface of the first plate portion is 2 to 8 degrees.

[0036] Effects of the Invention

[0037] According to the present invention, there can be provided a hot press device capable of suppressing the reduction in plate thickness and necking of a concave portion of a hot press-formed product formed by a die pad, a method for manufacturing a hot press-formed product using the device, and a hot press-formed product capable of suppressing the reduction in plate thickness and necking of a concave portion of a stamping-formed product. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic perspective view of a hot press-formed product according to one embodiment of the present invention.

[0039] Figure 2 It is a cross-section view along the Z coordinate axis. Figure 1 Schematic cutaway end view of a hot press-formed product.

[0040] Figure 3 It is magnified Figure 2 Schematic cutaway end view of the concave portion of a hot press-formed product.

[0041] Figure 4 This is a schematic perspective view of a hot pressing device according to one embodiment of the present invention.

[0042] Figure 5 It is a section view along the Z coordinate axis at the section line AA. Figure 4 Schematic cut-away end view of the hot pressing device shown.

[0043] Figure 6 This is a schematic cutaway end view for explaining a hot press device used in a method for producing a hot press-formed product according to an embodiment of the present invention, and is a view showing a state where a workpiece is placed.

[0044] Figure 7 This is a schematic cutaway end view for explaining a hot press device used in a method for producing a hot press-formed product according to an embodiment of the present invention, and is a view showing a state in which a recessed portion is formed in a workpiece.

[0045] Figure 8 This is a schematic cutaway end view for explaining a hot press device used in a method for producing a hot press-formed product according to an embodiment of the present invention, and is a view showing a state where press forming is completed.

[0046] Fig. 9 This is a schematic cutaway end view for explaining a hot press device used in a method for producing a hot press-formed product according to another embodiment of the present invention.

[0047] Fig.10 It is a schematic cutaway end view for explaining a hot press device used in a method for producing a hot press-formed product according to another embodiment of the present invention, and is a view showing a state where press forming is completed.

[0048] Fig.11 This is a schematic cutaway end view for explaining a hot press device used in a method for producing a hot press-formed product according to another embodiment of the present invention.

[0049] Fig.12 This is a schematic cutaway end view for explaining a recessed portion of a hot press-formed product according to an embodiment of the present invention.

[0050] Fig.13 This is a schematic cutaway end view of a hot press device according to one embodiment of the present invention.

[0051] Fig.14 This is a schematic cutaway end view of a hot press-formed product according to an embodiment of the present invention.

[0052] Fig.15 It is a diagram for explaining a modification example of the recessed portion according to one embodiment of the present invention, and is a schematic cutaway end view showing the vicinity of the recessed portion of a hot press-formed product.

[0053] Fig.16 It is a diagram for explaining a modification example of the recessed portion according to one embodiment of the present invention, and is a schematic cutaway end view showing the vicinity of the recessed portion of a hot press-formed product.

[0054] Fig.17 It is a schematic plan view for explaining a modified example of the recessed portion of the hot press-formed product of the present invention.

[0055] Fig.18 It is a schematic plan view for explaining a modified example of the recessed portion of the hot press-formed product of the present invention.

[0056] Fig.19 It is a schematic plan view for explaining a modified example of the recessed portion of the hot press-formed product of the present invention.

[0057] Fig. 20 It is a schematic plan view for explaining a modified example of the recessed portion of the hot press-formed product of the present invention.

[0058] Fig.21 It is a schematic plan view for explaining a modified example of the recessed portion of the hot press-formed product of the present invention.

[0059] Fig. 22 It is a schematic plan view for explaining a modified example of the recessed portion of the hot press-formed product of the present invention.

[0060] Fig.23 It is a schematic plan view for explaining a modified example of the recessed portion of the hot press-formed product of the present invention.

[0061] Fig.24 It is a graph showing the experimental results of Example 1.

[0062] Fig.25 This is a graph showing the experimental results of Example 2. DETAILED DESCRIPTION

[0063] Hereinafter, the embodiments of the present invention are described by way of example, but it is obvious that the present invention is not limited to the examples described below. In the following description, specific numerical values ​​and materials are sometimes illustrated, but as long as the effect of the present invention can be obtained, other numerical values ​​and materials can also be applied. In addition, each constituent element of the following embodiments can be combined with each other.

[0064] First, use Figure 1 A hot press molded product 100 obtained by the hot press apparatus and the method for producing a hot press molded product according to the present embodiment will be described.

[0065] [Thermoforming products]

[0066] Figure 1 1 is a perspective view of the hot press formed product 100 and includes a cross section perpendicular to the long side direction at the center of the long side direction of the hot press formed product 100. The cross section is also a cross section along the stamping direction P. Figure 1 As shown, the hot press-formed product 100 of the present embodiment is a long hot press-formed product 100, comprising: a first plate portion 110, extending along the long side direction of the hot press-formed product 100; a second plate portion 120, extending along the long side direction of the hot press-formed product 100 and inclined relative to the first plate portion 110; and a ridge portion 130, smoothly connecting the first plate portion 110 and the second plate portion 120 and extending along the long side direction of the hot press-formed product 100. The hot press-formed product 100 is a long strip component having a long side direction and a short side direction orthogonal to the long side direction. The long side direction is the direction in which the hot press-formed product 100 as a long strip component extends. In addition, in Figure 1 In the figure, the long side direction of the hot press formed product 100 is parallel to the Z coordinate axis. Figure 1 The X-coordinate axis and the Y-coordinate axis constitute a plane including the short side direction of the hot press formed product 100 . Figure 1 The X-axis, Y-axis, and Z-axis are orthogonal to each other.

[0067] exist Figure 1In the example, the portion of the first plate portion 110 other than the recessed portion 140 is substantially flat and extends along the long side direction of the hot press molded product 100. The portion of the first plate portion 110 other than the recessed portion 140 includes a first plate portion surface 110a and a first plate portion surface 110b opposite to the first plate portion surface 110a. When a direction parallel to the long side direction of the hot press molded product 100 is set as the long side direction of the first plate portion 110, the first plate portion 110 extends along the long side direction of the first plate portion 110.

[0068] The second plate portion 120 is a substantially flat plate-shaped portion that extends along the long side direction of the hot press molded product 100. The second plate portion 120 has a second plate portion surface 120a and a second plate portion surface 120b on the opposite side of the second plate portion surface 120a. When a direction parallel to the long side direction of the hot press molded product 100 is set as the length direction of the second plate portion 120, the second plate portion 120 extends along the length direction of the second plate portion 120. When a direction orthogonal to the length direction of the second plate portion 120 and the plate thickness direction of the second plate portion 120 is set as the width direction of the second plate portion 120, the second plate portion 120 extends along the width direction of the second plate portion 120. Figure 1 In the example of FIG. 1 , the hot press formed product 100 includes a pair of second plate portions 120 .

[0069] The ridge portion 130 is a portion that smoothly connects the first plate portion 110 and the second plate portion 120, and extends along the long side direction of the hot press molded product 100. The second plate portion 120 is inclined relative to the first plate portion 110, so the ridge portion 130 connecting them has a shape that is curved in a manner of describing a curve in a cross-section perpendicular to the long side direction of the hot press molded product 100. The second plate portion 120 is inclined relative to the first plate portion 110, which means that the plate surface of the first plate portion 110 and the plate surface of the second plate portion 120 are not parallel. In addition, the direction parallel to the long side direction of the hot press molded product 100 is set as the longitudinal direction of the ridge portion 130. The surface on the outer side of the curve of the ridge portion 130 is set as the ridge outer surface 130a, and the surface on the inner side of the curve of the ridge portion 130 is set as the ridge inner surface 130b. The first plate portion surface 110a and the second plate portion surface 120a are connected to the ridge outer surface 130a, and the first plate portion surface 110b and the second plate portion surface 120b are connected to the ridge inner surface 130b. An edge portion (first plate portion edge portion 110A) of one side of the first plate portion 110 extending along the long side direction of the hot press molded product 100 is connected to an edge portion (ridge edge portion 130A) of one side of the ridge portion 130 extending along the long side direction of the hot press molded product 100. An edge portion (second plate portion edge portion 120A) of one side of the second plate portion 120 extending along the long side direction of the hot press molded product 100 is connected to an edge portion (ridge edge portion 130B) of the other side extending along the long side direction of the ridge portion 130. Figure 1In the example of FIG. 1 , the hot press formed product 100 has a pair of ridge portions 130 .

[0070] The first plate portion 110 is provided with a recessed portion 140. When a direction parallel to the longitudinal direction of the hot press-formed product 100 is defined as a longitudinal direction of the recessed portion 140, the recessed portion 140 extends along the longitudinal direction of the recessed portion 140.

[0071] The recessed portion 140 may pass through the center position of the long side direction of the hot press molded product 100 and extend along the ridge portion 130. The center position of the long side direction of the hot press molded product 100 refers to a position included in the range from the center position that divides the length of the long side direction of the hot press molded product 100 into two equal parts to 20% of the length of the long side direction of the hot press molded product 100. The recessed portion 140 extending along the ridge portion 130 means that the recessed portion 140 is arranged to be substantially parallel to a part of the adjacent ridge portion 130.

[0072] In the second plate portion 120, a flange portion may be formed on the edge portion of the side that is not connected to the ridge portion 130 among the edge portions extending in the longitudinal direction. In addition, holes, cutouts, welded portions, etc. may be provided in the first plate portion 110, the second plate portion 120, or the flange portion. In addition, reinforcing ribs may be provided in the second plate portion 120 or the flange portion.

[0073] exist Figure 2 It is shown in Figure 1 The cut-off end view of the hot press molded product 100 is shown in the longitudinal direction of the hot press molded product 100, and is viewed along a plane perpendicular to the longitudinal direction of the hot press molded product 100. The recess 140 is recessed in a direction perpendicular to the plate surface of the first plate portion 110 as described later. Figure 2 In the example, the recessed portion 140 is recessed relative to the first plate portion 110 toward the side where the second plate portion 120 is located (the first plate portion plate surface 110 b side).

[0074] exist Figure 2 In the example of , the recess 140 has a bottom 141, a pair of side portions 142, a bottom side ridge portion 143, and a side side ridge portion 144. The bottom 141 of the recess is connected to each side portion 142 via a pair of bottom side ridge portions 143 at each end. Each side portion 142 is connected to the first plate portion 110 via a side side ridge portion 144. The bottom 141, the side portions 142, the bottom side ridge portion 143, and the side side ridge portion 144 extend along the length direction of the recess 140.

[0075] The bottom 141 of the recess 140 has a bottom inner surface 141a located inside the recess 140 (on the side 142 side) and a bottom outer surface 141b opposite to the bottom inner surface 141a. That is, the bottom inner surface 141a constitutes a part of the inner surface of the recess 140.

[0076] exist Figure 3 It is shown in Figure 2 An enlarged view of the concave portion 140 of the hot press molded product 100. In a plane perpendicular to the long side direction of the hot press molded product 100, one of the boundaries between the first plate portion 110 and the concave portion 140 (the boundary between the first plate portion 110 and the side edge portion 144) is set as boundary gb1, and the other boundary is set as boundary gb2. Figure 3 As shown, the boundary gb1 and the boundary gb2 on the plane perpendicular to the long side direction of the hot press molded product 100 are points on the plate surface outside the curved side edge line portion 144. In other words, these boundaries are also the R end ends on the plate surface outside the curved side edge line portion 144.

[0077] In the example of the present embodiment, the recessed portion 140 is a portion of the first plate portion 110 that is recessed toward the side where the second plate portion 120 is located (the first plate portion board surface 110b side). The recessed portion 140 may also be a portion of the first plate portion 110 that is recessed toward the side opposite to the side where the second plate portion 120 is located (the first plate portion board surface 110a side). That is, the recessed portion provided in the first plate portion 110 may also be recessed toward the ridgeline outer surface 130a side (the outer side of the hot press molded product 100) or the ridgeline inner surface 130b side (the inner side of the hot press molded product 100).

[0078] The distance between the boundary gb1 and the boundary gb2 of the concave portion in a plane perpendicular to the longitudinal direction of the hot press formed product 100 is defined as the width w of the concave portion 140. The width w of the concave portion 140 may not be constant in the longitudinal direction of the hot press formed product 100. Figure 1 The width w of the recess 140 is preferably 10 mm to 52 mm for the reasons of axial compression performance in the Z coordinate direction and bending moment performance in the X coordinate direction shown in the figure. The width w of the recess 140 is preferably smaller than the length of the recess 140 in the extending direction.

[0079] In addition, in the direction in which the hot press-formed product 100 as a long member extends, the direction of the boundary gb1 connecting both ends of the hot press-formed product 100 is defined as the longitudinal direction.

[0080] [Pressing device]

[0081] Next, a press device (hot press device) used in the method for producing a hot press-formed product according to the present embodiment will be described.

[0082] exist Figure 4 2 shows an example of a press device (hot press device) used in the method for producing a hot press-formed product according to the present embodiment. Figure 4The stamping device 1000 shown has a first die 1100, a second die 1200 and a third die 1300 as stamping dies. The first die 1100 and the second die 1200 can move relative to each other in a stamping direction P. A workpiece (blank) is sandwiched between the first die 1100 and the second die 1200. The third die 1300 is configured to be adjacent to the first die 1100 in a direction along the X-coordinate axis and can move relative to the first die 1100 and the second die 1200. In the example of the present embodiment, the third die 1300 can move relative to the first die 1100 and the second die 1200 in the stamping direction P. In addition, a refrigerant flow path (not shown) is provided inside the second die 1200 of the stamping device 1000. Here, the stamping direction P of the stamping device 1000 is the negative direction of the Y-coordinate axis. Figure 4 The X-axis, Y-axis, and Z-axis are orthogonal to each other.

[0083] The first mold 1100, the second mold 1200, and the third mold 1300 have long sides along the Z coordinate axis. Figure 5 It is shown in Figure 4 The section line AA shown is a schematic cut-away end view of the punching device 1000 in the direction along the Z coordinate axis. Figures 5 to 8 The end view is a cross-sectional view along the punching direction P.

[0084] The first die 1100 has a stamping surface 1110 and a convex portion 1120 disposed on the stamping surface 1110. Figure 5 In the example of , the convex portion 1120 has a bottom portion 1121 and a pair of side portions 1122. The bottom portion 1121 is connected to each side portion 1122 via a pair of bottom portion side ridges 1123 at each end. Figure 5 In the example, the convex portion 1120 protrudes in the negative direction of the Y coordinate axis. Each side portion 1122 is connected to the holding surface 1130 of the punching surface 1110 other than the convex portion 1120 via the side portion side ridge portion 1124. The bottom surface portion 1121, the side portion 1122, the bottom surface side ridge portion 1123, and the side portion side ridge portion 1124 are arranged along the direction in which the convex portion 1120 extends, that is, along the Figure 4 The Z coordinate axis extends in the direction of the

[0085] The second die 1200 has a punching surface (top surface) 1210 and a groove portion (concave portion) 1220 provided on the punching surface 1210. That is, the groove portion 1220 is provided on the top surface of the second die 1200. Figure 5In the example of FIG. 1 , the groove portion 1220 includes a bottom portion 1221, a pair of side portions 1222, a bottom portion side ridge portion 1223, and a side portion side ridge portion 1224. The bottom portion 1221 is connected to each side portion 1222 via a pair of bottom portion side ridge portions 1223 at each end. Figure 5 In the example, the groove 1220 has a shape that is concave toward the negative direction of the Y coordinate axis. Each side portion 1222 is connected to the holding surface 1230 of the punching surface 1210 other than the groove 1220 via the side edge line portion 1224. The bottom surface 1221, the side surface 1222, the bottom surface side edge line portion 1223, and the side surface side edge line portion 1224 have a certain length and extend in the direction in which the groove 1220 extends, that is, along the Figure 4 The second die 1200 further includes a side wall portion 1250, which is connected to the holding face portion 1230 via a shoulder portion 1240. The shoulder portion 1240 is a portion that smoothly connects the holding face portion 1230 and the side wall portion 1250. The shoulder portion 1240 and the side wall portion 1250 extend in the direction in which the stamping face 1210 extends, that is, along the Figure 4 The Z coordinate axis extends in the direction of the

[0086] The convex portion 1120 of the first die 1100 and the groove portion 1220 of the second die 1200 have surface shapes corresponding to each other, and the concave portion 140 is formed on the workpiece by sandwiching the workpiece between the first die 1100 and the second die 1200. In other words, the convex portion 1120 has a shape that is the inverse of the groove portion 1220. In addition, the holding surface portion 1130 of the first die 1100 and the holding surface portion 1230 of the second die 1200 are parallel to each other. In the example of this embodiment, the holding surface portion 1130 and the holding surface portion 1230 are perpendicular to the stamping direction P. In the first die 1100, the convex portion 1120 is provided at a position opposite to the groove portion 1220 in the stamping direction P.

[0087] In the cross section along the punching direction P, the wall surface of the groove portion 1220 has an angle of 2 to 8 degrees relative to the punching direction P. More specifically, the angle formed by the straight line connecting the R end of the side surface side ridge line portion 1224 located on the side of the side surface portion 1222 and the R end of the bottom surface side ridge line portion 1223 located on the side of the side surface portion 1222 in the cross section along the punching direction P and the punching direction P is 2 to 8 degrees. The cross section along the punching direction P refers to a plane in which the section line length of the groove portion 1220 is the shortest in the plane passing through the point on the bottom surface portion 1221 of the groove portion 1220 of the second mold 1200 where the depth is the deepest in the entirety of the groove portion 1220. The depth of the groove 1220 refers to the distance from the straight line connecting the boundaries of the pair of side edge lines 1224 and the holding surface 1230 to the bottom surface 1221 in a direction perpendicular to the straight line connecting the boundaries on a virtual plane including the shortest straight line connecting the boundaries of the pair of side ridges 1224 and the holding surface 1230 and where the section line length of the groove 1220 is the shortest when viewed in section. The section line length of the groove 1220 can be measured by making a 3D model based on three-dimensional shape measurement for the second mold 1200 and deriving the plane with the shortest section line length.

[0088] The curvature radius of the side edge line portion 1223 of the bottom portion is 3 mm to 30 mm. The curvature radius of the side edge line portion 1224 of the side portion is 3 mm to 30 mm. The curvature radius of the side portion 1222 exceeds 30 mm, or the side portion 1222 is a plane. Even if the side portion 1222 is curved within such a curvature radius, the wall surface of the groove portion 1220 in the above cross section can be approximated to a straight line, and the angle between the straight line connecting the R end ends and the punching direction P as described above can be specified.

[0089] The third die 1300 has a stamping surface 1310. The stamping surface 1310 is arranged along Figure 4 The first die 1100 and the third die 1300 are arranged to face the second die 1200 in the punching direction P. The first die 1100 is arranged to face the top surface of the second die 1200 .

[0090] In addition, the third die 1300 is connected to the sliding plate 1400. In addition, the first die 1100 is connected to the sliding plate 1400 via a support portion 1410 (spring, piston). The third die 1300 moves with the movement of the sliding plate 1400. The first die 1100 moves via the support portion 1410 with the movement of the sliding plate 1400. A driving portion (not shown) that can independently drive the first die 1100, the second die 1200, and the third die 1300 can also be provided in the stamping device 1000. In addition, any one of the first die 1100, the second die 1200, and the third die 1300 can also be fixed to the stamping device 1000.

[0091] Here, in the embodiment of the present application, the first die 1100 is set as a die pad, the second die 1200 is set as a punch, and the third die 1300 is set as a die.

[0092] [Method for producing hot press molded product]

[0093] The method for manufacturing a hot press molded product of the present embodiment is a method for manufacturing a hot press molded product by hot pressing a workpiece to form a stamped product including a first plate portion having a recessed portion. In the method for manufacturing a hot press molded product of the present embodiment, first, Figure 6 As shown in FIG. 1 , the workpiece (blank) 1 is placed between the first die 1100 and the second die 1200 . Figure 6 In the example, the first die 1100 is located on the upper side of the second die 1200 in the vertical direction, and the workpiece 1 is placed on the holding surface portion 1230 of the second die 1200 .

[0094] In the method for producing a hot press-formed product of the present embodiment, the temperature of the workpiece 1 at the start of press forming may be 600 to 800° C. This can achieve the effect that the hot press apparatus can form the member while the thermal deformation resistance is low.

[0095] Next, the first die 1100 and the second die 1200 are relatively moved in the stamping direction P (vertically downward) to approach each other. At this time, the third die 1300 may move together with the first die 1100, or the third die 1300 may not move. Thus, the first die 1100 and the second die 1200 sandwich the portion of the workpiece 1 corresponding to the first plate portion 110 in the hot press molded product 100.

[0096] Next, from the state where the convex portion 1120 of the first die 1100 is in contact with the workpiece 1, the first die 1100 is further moved in the punching direction P. Figure 7 As shown, the workpiece 1 is sandwiched between the first die 1100 and the second die 1200 , and a recess 140 is formed between the protrusion 1120 of the first die 1100 and the groove 1220 of the second die 1200 .

[0097] In the method for manufacturing a hot press molded product of this embodiment, the pressing force when forming the concave portion 140 by the first mold 1100 and the second mold 1200 may also be 0.4 to 22.0 MPa. More preferably, the pressing force may also be 0.4 to 4.4 MPa. Thus, the following effects can be obtained: molding can be performed during a period when the deformation resistance of the workpiece is low, and the molding load of the first mold 1100 can be set to the minimum load force, which can reduce the mold cost.

[0098] Afterwards, the third mold 1300 is further moved down to a point such as Figure 8 As shown, the workpiece 1 is sandwiched between the second die 1200 and the third die 1300, and the second plate portion 120 is formed between the second die 1200 and the third die 1300, completing the stamping. At this moment, the hot press molded product 100 is formed with the first plate portion 110, the second plate portion 120, the ridge portion 130, and the concave portion 140. In addition, a flange portion may also be formed between the second die 1200 and the third die 1300.

[0099] In addition, from the viewpoint of moldability, the first mold 1100 may reach the bottom point before the third mold 1300 reaches the bottom point, or the first mold 1100 may reach the bottom point at the same time as the third mold 1300 reaches the bottom point.

[0100] exist Fig. 9 A hot press device used in a method for producing a hot press-formed product according to another embodiment of the present invention is exemplified in FIG. Figure 5 same, Fig. 9 is Figure 4 The section line AA shown in the figure is a schematic cut-off end view of the punching device in the direction along the Z coordinate axis. Figures 9 to 11 The cut-off end view is a view of the cross section along the punching direction P. Fig. 9 The punching device 1000 shown in FIG. 1 is similar to the punching device 1000 shown in FIG. 1 in addition to having a step portion 1320. Figure 5 The punching device 1000 shown in FIG. 1 and FIG. 2 has the same structure, so the description thereof is omitted here. Fig. 9 The punching device 1000 shown in the figure can be applied to the above Figures 4 to 8 Configuration of the press device 1000 The step portion 1320 may extend in the direction along the Z coordinate axis.

[0101] In addition, Fig. 9 In the example of FIG. 1 , two third molds 1300 are shown in the X-coordinate axis direction. The two third molds 1300 may also be connected to each other in the X-coordinate axis direction.

[0102] Fig.10 FIG. 1 shows a state where a workpiece is clamped in the mold and the third mold 1300 is moved to the bottom. Fig.10 As shown, the workpiece is sandwiched between the second die 1200 and the third die 1300, and the second plate portion 120 is formed between the second die 1200 and the third die 1300, completing the stamping. At this moment, the hot press formed product 100 is formed with the first plate portion 110, the second plate portion 120, the ridge portion 130 and the concave portion 140.

[0103] Since the third die 1300 has the step portion 1320, the first die 1100 and the third die 1300 are in contact in the punching direction P at the point of the molding. Thus, the first die 1100 is pressed by the third die 1300, and necking can be suppressed even when the pressing force of the first die 1100 is insufficient. At this time, the support portion 1410 is deformed in a manner of shrinking in the punching direction P.

[0104] In addition, Fig.11 Other embodiments of the punching device 1000 are shown in FIG. Figure 5 Same as above, Fig.11 The punching device 1000 is also Figure 4 The section line AA shown is a schematic cutaway end view of the punching device in the direction along the Z coordinate axis. Fig.11 The punching device 1000 shown is provided with the third die 1300 only on one side. In addition, the third die 1300 has a step portion 1320. In addition, the first die 1100 has a punching surface 1140 on the side opposite to the third die 1300 in the X-axis direction. The punching surface 1140 is provided to be connected to the punching surface 1110 of the first die 1100. The punching surface 1140 extends in the direction along the Z coordinate axis.

[0105] Fig.11 The punching device 1000 shown is similar to the punching device 1000 except that the third die 1300 is only provided on one side. Fig. 9 The punching device 1000 shown in the figure has the same structure, so the description is omitted here. Fig.11 The punching device 1000 shown can be used Fig. 9 The structure of the punching device 1000 is as follows. Fig.11 In the punching device 1000, the area where the pressing mechanism of the third die 1300 is arranged on the upper side of the punching device 1000 can be increased, so there is an advantage that the punching load design can have a likelihood.

[0106] In the manufacturing method of the hot press formed product of the present embodiment, stamping can also be performed so that the ratio of the area of ​​the recessed portion 140 to the area of ​​the first plate portion 110 when viewed from a direction perpendicular to the plate surface of the first plate portion 110 is 30% or more. The direction perpendicular to the plate surface of the first plate portion 110 refers to a direction orthogonal to the straight line connecting the boundary gb1 and the boundary gb2 on an imaginary plane including the shortest straight line connecting the boundary gb1 and the boundary gb2 and in which the section line length of the recessed portion 140 becomes the shortest when viewed in section. In addition, by making a 3D model based on three-dimensional shape measurement for the hot press formed product 100 and deriving a plane with the shortest section line length, the section line length of the recessed portion 140 can be measured. In addition, the three-dimensional shape measurement described in the present embodiment can be measured using a 3D scanner such as Atos (manufactured by GOM).

[0107] The definitions of the area of ​​the first plate portion 110 and the area of ​​the recessed portion 140 will be described later.

[0108] In the manufacturing method of the hot press formed product of the present embodiment, stamping can also be performed so that the maximum depth dmax of the depth d of the recess 140 in the stamping direction P is greater than or equal to 15 mm. The depth d of the recess 140 refers to the depth in the stamping direction P. The stamping direction P is a direction perpendicular to the plate surface of the first plate portion 110. The maximum depth dmax refers to the maximum value of the depth d of the recess 140 in the entire recess 140. By making the maximum depth dmax greater than or equal to 15 mm, it is possible to obtain a method that can improve the depth d of the recess 140 along the stamping direction P. Figure 1 The depth of the recess 140 refers to the distance from the straight line perpendicular to the plate surface of the first plate portion 110 to the bottom inner surface 141a.

[0109] The maximum depth dmax is preferably 20 mm or more for the purpose of further improving the axial force and bending moment performance. More preferably, the upper limit of the maximum depth dmax is preferably 50 mm from the viewpoint of suppressing the deterioration of productivity caused by the increase in the press stroke due to the increase in the pad stroke.

[0110] In the manufacturing method of the hot press formed product of the present embodiment, when forming the recess 140, the punching is performed in such a manner that the angle α formed by the side portion 142 of the recess 140 and the punching direction P is 2 to 8° in a plan view of a plane (a cross section cut in the punching direction) where the length of the section line of the recess 140 in a plane passing through the point pd where the depth d of the recess 140 is the deepest becomes the shortest. More specifically, the punching is performed in such a manner that the angle formed by the straight line connecting the R end of the side side ridge line portion 144 located on the side of the side portion 142 and the R end of the bottom side ridge line portion 143 located on the side of the side portion 142 and the punching direction P is 2 to 8° in a plane where the length of the section line of the recess 140 in a plane passing through the point pd where the depth d of the recess 140 is the deepest becomes the shortest. The plane passing through the point pd where the depth d of the recess 140 is deepest and where the length of the cross section of the recess 140 is shortest is parallel to the punching direction P. The point pd where the depth d of the recess 140 is deepest is the point where the depth d of the recess 140 reaches the maximum depth dmax in the entire recess 140 .

[0111] The curvature radius of the bottom side edge line portion 143 is 3 mm to 30 mm. The curvature radius of the side side edge line portion 144 is 3 mm to 30 mm. The curvature radius of the side portion 142 exceeds 30 mm, or the side portion 142 is a plane. Even if the side portion 142 is curved within such a curvature radius, the side portion 142 can be approximated to a straight line in the above cross section, and the angle between the straight line connecting the R end ends and the punching direction P as described above can be specified.

[0112] exist Fig.12 2 shows an end view of a cut portion in a cross-sectional view of a plane where the length of a section line of the recessed portion 140 becomes shortest in a plane passing through a point pd where the depth d of the recessed portion 140 is the deepest. Fig.12 FIG. 1 shows a hot press-formed product 100 placed on a press device 1000 after the press forming is completed, and is an enlarged view of the vicinity of the concave portion 140 of the hot press-formed product 100. Fig.12 As shown, the cross-sectional length of the concave portion 140 is the length of the line from the boundary gb1 to the boundary gb2 along the inner surface of the concave portion 140 in the plane including the shortest straight line connecting the boundary gb1 and the boundary gb2. The cross section determined by the curve C corresponding to the shape of the concave portion 140 is a plane where the cross-sectional length of the concave portion 140 is the shortest in the plane passing through the point pd.

[0113] Curve C corresponds to the shape of the inner surface of the concave portion 140 in the cross section. Curve C has one end point of the side portion 142, namely point iP1 and point iP2, between the boundary gb1 or the boundary gb2 and the point pd. Point iP1 and point iP2 are also the R end points of the side ridgeline portion 144. By performing stamping in such a manner that the angle α formed by the side portion 142 of the concave portion 140 and the stamping direction P in the cross section becomes 2 to 8°, the processing and forming of the concave portion 140 formed by the first die 1100 can be made to be closer to the forming height of the point, and the reduction of the plate thickness and the necking of the concave portion can be suppressed. By making the angle α greater than 2°, it has the effect of being easy to demold after stamping. In addition, by making the angle α less than 8°, when the first die 1100 is used for molding, the parts of the workpiece 1 that are not in contact with the first die 1100 or the second die 1200 can be reduced, and the parts that cannot be cooled can be reduced. When there are few places where cooling is not possible, the thickness reduction during molding of the workpiece 1 does not occur locally to cause necking, so there is an effect that a member can be molded without excessive thickness reduction or necking.

[0114] In addition, if Fig.12 As shown in the example, when the side portion 142 of the concave portion 140 is flat, the slope of the side portion 142 is consistent with the slope of the tangent line ti1 or the slope of the tangent line ti2. In addition, the slope of the tangent line ti1 or the slope of the tangent line ti2 is consistent with the slope of the straight line connecting the R end of the side side ridge line portion 144 located on the side of the side portion 142 and the R end of the bottom side ridge line portion 143 located on the side of the side portion 142. Fig.12 In the examples, the side portions 142 are depicted as having the same slope with respect to the punching direction P. However, as long as the angle requirements with respect to the punching direction P are satisfied, the angles of the two side portions 142 with respect to the punching direction P may be different from each other.

[0115] In the hot press-formed article 100 obtained by the above manufacturing method, the ratio of the area of ​​the concave portion 140 to the area of ​​the first plate portion 110 when viewed from a direction perpendicular to the plate surface of the first plate portion 110 may be 30% or more. The area of ​​the first plate portion 110 refers to the area of ​​the portion including the concave portion 140 and excluding the second plate portion 120 and the ridgeline portion 130 between the second plate portion 120.

[0116] The area of ​​the concave portion 140 is the area from the boundary gb1 to the boundary gb2 when viewed from the direction perpendicular to the plate surface of the first plate portion 110. By making the area of ​​the concave portion 140 viewed from the direction perpendicular to the plate surface of the first plate portion 110 30% or more relative to the area of ​​the first plate portion 110, it is possible to improve the Figure 1In order to further improve the axial force and bending moment performance, the area of ​​the recess 140 is more preferably 50% or more of the area of ​​the first plate portion 110.

[0117] The area of ​​the first plate portion 110 is the area of ​​the range surrounded by the boundary between the ridge portion 130 and the first plate portion 110 and the end portion in the long side direction of the first plate portion 110 in a plan view in a direction perpendicular to the plate surface of the first plate portion 110. By making a 3D model based on three-dimensional shape measurement for the hot press molded product 100 and detecting the boundary between the first plate portion 110 and the ridge portion 130 from the 3D model, the boundary between the first plate portion 110 and the ridge portion 130 can be determined. The area of ​​the recessed portion 140 is similarly the area of ​​the range on the side of the recessed portion 140 surrounded by the boundary between the side ridge portion 144 and the first plate portion 110. By making a 3D model based on three-dimensional shape measurement for the hot press molded product 100 and detecting the boundary between the first plate portion 110 and the side ridge portion 144 from the 3D model, the boundary between the first plate portion 110 and the side ridge portion 144 can also be determined.

[0118] The hot press formed article 100 of this embodiment may be such that the maximum depth dmax of the recess 140 in the direction perpendicular to the plate surface of the first plate portion 110 is 15 mm or more. By setting the maximum depth dmax to 15 mm or more, it is possible to improve the Figure 1 The maximum depth dmax is more preferably 20 mm or more in order to further improve the axial force and bending moment performance.

[0119] The depth d of the recess 140 refers to the distance from the shortest straight line connecting the boundary gb1 and the boundary gb2 to the bottom inner surface 141a in a direction orthogonal to the straight line connecting the boundary gb1 and the boundary gb2 on an imaginary plane including the shortest straight line connecting the boundary gb1 and the boundary gb2 and where the section line length of the recess 140 is the shortest when viewed in section.

[0120] In the hot press formed product 100 obtained by the above-mentioned manufacturing method, in the cross-section of the plane passing through the point pd where the depth d of the recess 140 is the deepest and the section line length of the recess 140 is the shortest, the angle formed by the side portion 142 of the recess 140 and the direction perpendicular to the plate surface of the first plate portion 110 is 2 to 8 degrees.

[0121] In addition, the plate thickness of the portion with the smallest plate thickness in the recessed portion 140 is 60% or more of the plate thickness of the portion other than the recessed portion 140 in the first plate portion 110. Here, the plate thickness of the portion other than the recessed portion 140 means that the plate thickness of the portion other than the recessed portion 140 in the first plate portion 110 is the average value of the plate thickness of any three points in the portion other than the recessed portion 140 in the first plate portion 110. In addition, a plane passing through the point pd where the depth d of the recessed portion 140 is the deepest and where the length of the section line of the recessed portion 140 becomes the shortest is perpendicular to the plate surface of the first plate portion 110. According to the above-mentioned manufacturing method, it is possible to suppress the plate thickness reduction of the recessed portion, so that in the hot press formed product 100, the plate thickness of the portion with the smallest plate thickness in the recessed portion 140 can be 60% or more of the plate thickness of the portion other than the recessed portion 140 in the first plate portion 110.

[0122] In the hot press formed article 100 of the present embodiment, when a load of a certain value or more is applied in a direction perpendicular to the longitudinal direction of the hot press formed article 100 or in the longitudinal direction of the hot press formed article 100, deformation occurs. At this time, a tensile force or a compressive force is applied in a direction perpendicular to the extending direction of the recessed portion 140. In the hot press formed article 100 of the present embodiment, by making the plate thickness of the portion with the smallest plate thickness in the recessed portion 140 at least 60% of the plate thickness of the portion of the first plate portion 110 other than the recessed portion 140, the axial force and bending moment performance of the component generated by the recessed portion 140 can be improved.

[0123] As described above, a 3D model based on three-dimensional shape measurement is prepared for the hot press formed product 100 , and the plate thickness is detected from the 3D model, thereby measuring the plate thickness of the first plate portion 110 and the recessed portion 140 .

[0124] In the hot press formed product of the present embodiment, the average plate thickness t1 of the first plate portion 110 may also be 0.8 to 2.6 mm. The plate thickness of the workpiece 1 is measured at more than three locations from the 3D model, and the arithmetic mean of the measured values ​​of the plate thickness at these locations is set as the average plate thickness t1 of the workpiece 1. The average plate thickness t1 of the first plate portion 110 is determined by the following method. In a plane orthogonal to the long side direction of the hot press formed product 100 at the center position of the long side direction of the hot press formed product 100, the plate thickness of any position of the first plate portion 110 other than the recessed portion 140 is measured at more than three locations from the 3D model. The arithmetic mean of the measured values ​​of the plate thickness at these locations is set as the average plate thickness t1.

[0125] In the method for manufacturing a hot press-formed product of the present embodiment, the average thickness t of the workpiece 1 may be 0.8 to 2.6 mm. The thickness of the workpiece 1 at three or more locations is measured from the 3D model, and the arithmetic mean of the measured values ​​of the thickness at these locations is set as the average thickness t of the workpiece 1.

[0126] In the convex portion 1120 of the first die 1100 used in the method for manufacturing a hot press formed product of the present embodiment, the maximum distance in the stamping direction from the stamping surface 1110 to the convex portion 1120 may also be 15 mm or more. In the first die 1100 used in the method for manufacturing a hot press formed product of the present embodiment, the stamping direction intersects the stamping surface 1110. Here, the maximum distance in the stamping direction from the stamping surface 1110 to the convex portion 1120 refers to the maximum distance in the stamping direction from the holding surface portion 1130 to the convex portion 1120.

[0127] In addition, in a cross-sectional view of a plane passing through a point where the distance from the stamping surface 1110 of the first mold 1100 to the protrusion 1120 is the longest and the section line length of the protrusion 1120 is the shortest, in a curve corresponding to the surface shape of the protrusion 1120, the side surface portion 1222 of the groove portion 1220 of the second mold 1200 has an angle of 2 to 8 degrees relative to the stamping direction.

[0128] The stamping die or stamping device used in the manufacture of the hot press-formed product of the present invention is not limited to the above-mentioned structure, and various modifications can be applied as long as the structure can implement the above-mentioned stamping. For example, as an embodiment, Fig.13 As shown, the punching device 2000 may further include a fourth die 2400. Figure 5 same, Fig.13 This is a schematic cut-off end view of the stamping device 2000 in a direction along the long side direction of the first die 2100. The first die 2100, the second die 2200 and the third die 2300 are configured as described above. During stamping, the fourth die 2400 clamps the second plate portion 120 and the flange portion connected to the second plate portion 120 together with the third die 2300 while processing. By further providing the fourth die 2400, it is possible to suppress the generation of wrinkles on the flange portion. In addition, the third die 2300 is connected to the sliding plate 1400. In addition, the first die 2100 is connected to the sliding plate 1400 via the support portion 1410 (spring, piston).

[0129] In the hot press molded article 100 of the present invention, as one embodiment, Fig.14 As shown in the example, in the cross-section of the hot press molded product 200 in the longitudinal direction, a recess 250 shallower than the recess 240 may be further provided in the first plate portion 210. Figure 1 Such effects include axial compressive force performance in the direction of the Z coordinate axis and bending moment performance in the direction along the X coordinate axis.

[0130] In the above embodiment, the hot press formed product 100 including two second plate portions 120 is described as an example. However, the hot press formed product of the present invention may include the second plate portion 120 on only one side of the first plate portion 110 .

[0131] In addition, in the above embodiment, the hot press molded product 100 having the second plate portion 120 connected to the first plate portion 110 via the ridge portion 130 is described, but the hot press molded product of the present invention may not have the second plate portion and the ridge portion. That is, even if the hot press molded product 100 is composed of the first plate portion 110 provided with the recessed portion 140, the effect of the present invention such as suppressing the reduction of the plate thickness and the necking of the recessed portion 140 can be obtained.

[0132] In addition, the hot press formed product 100 of the above embodiment is preferably a long strip component. That is, when viewed from a direction perpendicular to the plate surface of the first plate portion 110, the size of the long side direction of the first plate portion 110 is preferably larger than the size of the short side direction. In addition, the size of the long side direction and the size of the short side direction of the first plate portion 110 may be the same. The recess 140 may be provided along the long side direction of the first plate portion 110, and a part of the recess 140 may also be provided along the short side direction of the first plate portion 110. Alternatively, a part of the recess 140 may also extend in a direction intersecting the long side direction or the short side direction of the first plate portion 110.

[0133] The hot press molded product 100 of the above embodiment has a tensile strength of 1470 MPa or more. By making the tensile strength of the hot press molded product 100 be 1470 MPa or more, a certain yield stress can be ensured and strain can be suppressed. Based on the reason of having a higher yield stress, the tensile strength of the hot press molded product 100 is more preferably 2000 MPa or more. The tensile strength of the hot press molded product 100 is obtained as follows. Specifically, a sample of a size that meets any one of the JIS No. 5 tensile test, the JIS No. 13B tensile test, or the JIS No. 14B tensile test is obtained from the first plate portion 110 or the second plate portion 120 of the hot press molded product 100, and the tensile strength of the sample is measured by a method that meets JIS Z 2241 using a universal testing machine and a hydraulic servo strength testing machine, and the tensile strength is set as the tensile strength of the hot press molded product 100. In addition, when it is impossible to collect a test piece specified by JIS, a micro tensile test piece can also be used as a sample. In the micro tensile test, the width and thickness of the parallel portion are preferably 0.2 to 2.0 mm, and the shape of the test piece is preferably such that a uniform load is applied to the parallel portion of the tensile test. The test piece is preferably processed by wire cutting and discharge machining. For example, the micro tensile test piece can be the following test piece: Journal of the Welding Society, Vol. 75 (2006), No. 6, pp. 461-465 (https: / / www.jstage.jst.go.jp / article / jjws / 75 / 6 / 75_6_461 / _pdf / -char / ja).

[0134] In the hot press formed product 100 of the above embodiment, the length in the long side direction is more preferably 700 to 1700 mm, and the length in the width direction of the first plate portion 110 (the length from the first plate portion edge portion 110A to the other edge portion) is more preferably 30 to 200 mm. In addition, in the hot press formed product 100 of the above embodiment, the length in the width direction of the second plate portion 120 is more preferably 30 to 200 mm.

[0135] In the hot press formed product of the above embodiment, the recess may have Fig.15 A V-shaped cross-sectional shape including a portion of a curve as shown or Fig.16 The cross-sectional shape is composed of curves as shown.

[0136] In addition, if Fig.15As shown in the example, the concave portion 340 of the hot press molded product 300 may also have a bottom 341 whose cross section is formed by a curve and a pair of side portions 342. The bottom 341 is connected to the side portions 342, and each side portion 342 is connected to the first plate portion 310 via the side edge line portion 344. The first plate portion 310 has a first plate portion board surface 310a and a first plate portion board surface 310b on the opposite side of the first plate portion board surface 310a. The bottom 341 has a bottom inner surface 341a located inside the concave portion 340 and a bottom outer surface 341b on the opposite side of the bottom inner surface. In a plane orthogonal to the long side direction of the hot press molded product 300, one of the boundaries between the first plate portion 310 and the concave portion 340 (the boundary between the first plate portion 310 and the side edge line portion 344) is set as the boundary gb1, and the other boundary is set as the boundary gb2. The boundary gb1 and the boundary gb2 on the plane perpendicular to the long side direction of the hot press molded product 300 are points on the plate surface outside the curved side edge line portion 344. The distance between the boundary gb1 and the boundary gb2 on the plane perpendicular to the long side direction of the hot press molded product 300 is set to the width of the concave portion 340. Fig.15 In the case of the shape shown, the definition of the curve corresponding to the shape of the recessed portion is also the same as in the above-described embodiment.

[0137] exist Fig.16 In the example, the recess 440 does not have Figure 3 The flat side portion as shown in the example is formed by a curve corresponding to the shape of the inner surface of the recessed portion 440. The curve is formed by a curve portion 441 and a curve portion 442, and the intersection point of the curve portion 441 and the curve portion 442 is a point ip.

[0138] The shape of the first plate portion of the recessed portion of the press-formed product of the present invention when viewed from above is not particularly limited. Figure 17 to Figure 23 A modified example of the recessed portion provided in the first plate portion is illustrated in FIG. Figure 17 to Figure 23 2 and 3 , only the shape of the recessed portion provided in the first plate portion is schematically shown.

[0139] The press-formed product of the above-mentioned embodiment is preferably used as a hot press-formed product for a vehicle such as a front bumper reinforcement, a rear bumper reinforcement, a rocker outer member, a rocker inner member, a door anti-collision beam, a front side member, a rear side member, etc.

[0140] Example

[0141] (Example 1)

[0142] In Example 1, on the simulator, Fig.14The hot press formed product with three concave parts as shown in the figure was subjected to a three-point bending test. The plate thickness of the workpiece was 1.2 mm, and the tensile strength of the workpiece was 2000 MPa level. The simulation conditions of the three-point bending test were three-point bending in which the center of the component was statically pressed down, and the plate thickness of the central concave part of the component was set to the plate thickness obtained by the forming simulator. In addition, in this embodiment, the span of the support fixture for the three-point bending was set to 1000 mm.

[0143] The area ratio of the concave portion is 40%, the maximum depth is 15 mm, and the width is 35 mm, so that the angle between the side of the concave portion and the stamping direction during stamping is changed as shown in Table 1. In addition, the plate thickness reduction rate and component performance (yield strength) of the concave portion were investigated. The results are shown in Table 1. Here, based on the arithmetic average ta of the plate thickness of any three points in the first plate portion other than the concave portion, and the plate thickness tmin of the thinnest part of the concave portion, (ta-tmin) / ta is set as the plate thickness reduction rate of the concave portion. On the simulator, the plate thickness reduction rate of the concave portion can be calculated by dividing the plate thickness of the portion where the plate thickness is reduced the most in the concave portion by the plate thickness of the first plate portion. Based on the simulation results of the 3-point bending test, the yield strength of the component used to evaluate the performance of the component is calculated. Here, the yield strength is a value obtained by dividing the load received by the impactor from the test body in the 3-point bending test by the weight, and it is evaluated as the component performance. In addition, the load in Table 1 is the load received by the impactor from the test body, and the weight is the weight of the hot press molded product.

[0144] [Table 1]

[0145]

[0146] In addition, Fig.24 The results of this simulation are shown in Fig.24 It can be confirmed that the plate thickness reduction rate can be suppressed by making the angle of the side of the recess less than 8° relative to the stamping direction. In addition, it can be seen that by making the angle of the side of the recess in the range of 2 to 8° relative to the stamping direction, the target component performance of 7.96 kN / kg or more can be exerted. In addition, it can be seen that by making the angle of the side of the recess more than 2° relative to the stamping direction, the stamped product can be easily demolded from the mold. Based on these results, the parts judged to be good in comprehensive component performance are set to B (Good), and the other parts are set to C (Bad). In the stamped products of Examples 1 to 3, the angles formed by the side of the recess and the direction perpendicular to the plate surface of the first plate portion are the same as the angles formed by the side of the recess and the stamping direction. In addition, in Examples 1 to 3, the angle of the side of the recess relative to the stamping direction is defined as in the above-mentioned embodiment.

[0147] (Example 2)

[0148] In Example 2, on the simulator, Figure 1 The three-point bending test was conducted on a hot press-formed product having a shape with one concave portion as shown in FIG. The plate thickness of the workpiece was 2.01 mm, and the tensile strength of the workpiece was 2000 MPa level. The simulation conditions of the three-point bending test were three-point bending in which the center of the component was statically pressed down, and the plate thickness of the central concave portion of the component was set to the plate thickness obtained by the forming simulation. In addition, in this embodiment, the span of the support fixture for the three-point bending was set to 1000 mm.

[0149] The area ratio of the concave portion is 35%, the maximum depth is 20 mm, and the width is 35 mm. The angle between the side of the concave portion and the stamping direction during stamping is changed as shown in Table 2, and the plate thickness reduction rate and component performance (yield strength) of the concave portion are investigated. The results are shown in Table 2. Here, the plate thickness reduction rate of the concave portion, the definition of component performance, and the calculation method are the same as those in Example 1. In addition, the definitions of the loads, etc. in Table 2 are the same as those in Table 1.

[0150] [Table 2]

[0151]

[0152] In addition, Fig.25 The results of this simulation are shown in Fig.25 It can be confirmed that by making the angle of the side of the recess less than 8° relative to the stamping direction, the plate thickness reduction rate can be suppressed. In addition, it can be seen that by making the angle of the side of the recess in the range of 2 to 8° relative to the stamping direction, a higher component performance of 7.50 kN / kg or more as the target can be achieved. In addition, it can be seen that by making the angle of the side of the recess more than 2° relative to the stamping direction, the mold can be easily demolded from the stamped product. Based on these results, the parts with good comprehensive component performance are set to B (Good), and the other parts are set to C (Bad).

[0153] (Example 3)

[0154] As shown in Table 3, the plate thickness of the workpiece, the number of recesses, the tensile strength of the workpiece, and the pad pressure during molding (pressing force of the first mold) were changed, and a three-point bending test of the test body was carried out on the simulator, and a comprehensive evaluation was performed based on the yield strength performance of the component and the mold cost. Regarding the cross-sectional dimensions, the height of the second plate portion is 65 mm, the width of the first plate portion is 100 mm, the width of the recess is 40 mm, and the depth is 23 mm. The angle of the side of the recess is 5° relative to the stamping direction. When the number of recesses in the first plate portion is 1, it is arranged in the center of the width direction. When there are 2 recesses, a shallow groove with a depth of 8 mm is set between the recess in the center of the width direction and the second plate portion. The results are shown in Table 3. In addition, in this embodiment, the span of the support fixture for 3-point bending is set to 1300 mm.

[0155] [Table 3]

[0156]

[0157] In Table 3, in the evaluation criteria of mold cost, the condition of a cushion pressure of 10.0 MPa or less is set as A (Very Good), and the condition of a cushion pressure exceeding 10.0 MPa and 50.0 MPa or less is set as B (Good). In addition, in the comprehensive evaluation, a component whose yield strength performance evaluation result is 6.6 kN / kg or more and whose mold cost meets the B condition, or a component whose yield strength performance evaluation result is less than 6.6 kN / kg but whose mold cost meets the A condition is set as A (Very Good), and a component whose yield strength performance evaluation result is less than 6.6 kN / kg and whose mold cost meets the B condition is set as B (Good).

[0158] Industrial Applicability

[0159] According to the present invention, a hot pressing device capable of suppressing the reduction in plate thickness and necking of a concave portion of a hot pressing-formed product formed by a die pad, a method for manufacturing a hot pressing-formed product using the device, and a hot pressing-formed product capable of suppressing the reduction in plate thickness and necking of a concave portion of a stamping-formed product can be provided, and therefore the hot pressing device is extremely useful in industry.

[0160] Explanation of symbols

[0161] 100: hot-pressed product; 110: first plate portion; 120: second plate portion; 130: ridge portion; 140: recessed portion; 141: bottom portion; 142: side portion; 143: bottom side ridge portion; 144: side side ridge portion; 1000: stamping device; 1100: first die (die pad); 1200: second die (punch); 1300: third die (die).

Claims

1. A hot pressing device, characterized in that: The hot pressing device comprises a punch, a die and a die pad. The top surface of the punch has a groove. In the cross section along the punching direction, the angle between the wall surface of the groove and the punching direction is 2 to 8 degrees. The punch has a refrigerant flow path inside. The die and the die pad are arranged to face the punch in the punching direction. The die pad is disposed facing the top surface of the punch. The die pad has a convex portion at a position facing the groove portion in the punching direction, and the convex portion has a shape that is an inversion of the groove portion.

2. The hot pressing device according to claim 1, characterized in that: The punching die has a step portion that contacts the punching die pad in the punching direction. At the point of forming, the die pad contacts the die in the punching direction.

3. The hot pressing device according to claim 1, characterized in that: In the cross section, an angle formed by a straight line connecting an R end of a side ridge line portion and an R end of a bottom ridge line portion of a wall surface of the groove portion and the punching direction is 2 to 8 degrees.

4. A method for manufacturing a hot press molded product, using the hot press device according to any one of claims 1 to 3, characterized in that: include: Disposing a blank between the die and the punch; clamping the blank by the punch and the die pad; as well as The punch and the die are brought close to each other in the stamping direction until the forming point is reached.

5. A hot press formed product comprising a first plate portion having a recessed portion and a second plate portion inclined relative to the first plate portion, wherein: In a cross-sectional view of a plane passing through a point where the depth of the recess is the deepest and where the length of the section line of the recess is the shortest, an angle formed between a side portion of the recess and a direction perpendicular to the plate surface of the first plate portion is 2 to 8 degrees, The plate thickness of a portion of the recessed portion where the plate thickness is smallest is 60% or more of the plate thickness of a portion of the first plate portion other than the recessed portion.

6. The hot press formed product according to claim 5, characterized in that In the cross-sectional view, an angle formed by a straight line connecting the R end of the side ridge line portion of the side portion of the recess and the R end of the bottom ridge line portion and a direction perpendicular to the plate surface of the first plate portion is 2 to 8 degrees.

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