JP7350607B2 - Automotive panel manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing an automobile panel.

2. Description of the Related Art Conventionally, as an automobile panel, for example, an outer panel that constitutes the outer surface of an automobile door is known. This outer panel is manufactured by press-molding a metal plate. Character lines forming ridgelines are applied to the outer panel for design purposes, and in recent years, there has been a demand for sharper character lines to improve design characteristics. Press molding into a shape with sharp character lines may cause molding defects or surface quality defects. Patent Document 1 listed below proposes a method for manufacturing an outer panel that can form sharper character lines while suppressing the occurrence of molding defects and surface quality defects.

Specifically, in the manufacturing method proposed in Patent Document 1 below, the outer panel is manufactured by two-step press forming. and a second pressing step in which the intermediate-shaped plate material formed in the first pressing step is molded into the final target shape of the outer panel having sharp character lines. The intermediate shape has a gently curved shape with a larger radius of curvature than the target shape only near the character line, and has a shape that is equal to the target shape except around the character line. In the first press process, the plate material is once formed into such an intermediate shape, and then in the second press process, a sharp character line is formed, thereby suppressing the occurrence of forming defects and surface quality defects, and creating a sharp character line. It is now possible to form character lines that are unique.

Patent No. 5959702

However, in the manufacturing method disclosed in Patent Document 1, there is a risk that the manufacturing cost increases, the yield of the manufactured outer panel decreases, and there is a risk that molding marks remain on the outer panel.

Specifically, in the manufacturing method disclosed in Patent Document 1, a mold is used to form the plate material into an intermediate shape in the first pressing process, and a mold to form the plate material into the target shape in the second pressing process. Since it is necessary to prepare these separately, the cost for the mold increases, and as a result, the manufacturing cost increases. In addition, since the process of forming the plate material into the target shape is divided into two processes, the first press process and the second press process, a yield is generated for each press process, and the final output of the outer panel is Yield decreases. In addition, there is a possibility that the forming marks created when the plate material is formed into an intermediate shape in the first pressing process are not removed in the second pressing process, and the forming marks remain on the finally manufactured outer panel.

It is an object of the present invention to form sharper character lines, to suppress increases in manufacturing costs and decreases in the yield of manufactured automotive panels, and to prevent molding marks from remaining on manufactured automotive panels. An object of the present invention is to provide a method for manufacturing an automobile panel that can prevent the above-mentioned problems.

The method for manufacturing an automobile panel provided by the present invention is a method for manufacturing an automobile panel in a target shape having character lines by press-molding a plate-shaped blank material having a predetermined thickness. In this manufacturing method, the blank material is arranged between a die having a concave portion and a punch having a convex portion arranged to face the concave portion, and a forming target area of the blank material is formed into the target shape. a holding step of holding a peripheral portion around the holder with a holder; and a forming step of forming the region to be formed into the target shape between the concave portion and the convex portion by bringing one of the die and the punch closer to the other. It comprises a process. The inner surface of the recess has a valley line portion provided at the bottom of the recess at a position facing the top of the protrusion. In the forming step, the region to be formed is pressed against the top , and the region to be formed is bent and deformed with the character line formation location where the character line is formed as the vertex, and the bending and deformation is performed. A first adjacent location adjacent to the character line forming location on one side of the target area and a second adjacent location adjacent to the character line forming location on the opposite side of the first adjacent location are arranged in the recessed portion. sandwiched between the inner surface and the top of the convex portion, and at the time of the sandwiching, a gap is left between the character line forming location and the valley line portion of the inner surface of the concave portion; Thereafter , the first adjacent portion and the second adjacent portion are connected to the inner surface of the recess and the top portion such that the thickness of both the first adjacent portion and the second adjacent portion is smaller than the predetermined thickness. By press-forming between the parts, the material corresponding to the reduced thickness flows into the area between the first adjacent part and the second adjacent part, and the thickness of the character line forming part is compensated for. be done .

In this method for manufacturing an automobile panel, in the molding process, the character line forming point is sandwiched between the inner surface of the recess of the die and the top of the punch, so that the first adjacent point and the second adjacent point on both sides of the character line forming point are sandwiched between the inner surface of the recess of the die and the top of the punch. It is possible to suppress the material in the vicinity from flowing to the outside of both the first and second adjacent parts, thereby suppressing thinning in the vicinity of the character line forming part, and also to reduce the thickness of the first and second adjacent parts to the original predetermined thickness. A character line is formed by press-molding the first and second adjacent portions so that the thickness of the first and second adjacent portions is smaller than the thickness of the first and second adjacent portions, and causing material corresponding to the reduced thickness of the first and second adjacent portions to flow near the character line forming portion. The thickness near the location can be compensated for, and as a result, flattening of the outer surface near the location where the character line is formed can be suppressed, and a sharper character line can be formed.

Moreover, with this manufacturing method, the area to be formed of the blank material can be press-formed into a target shape with character lines in one forming process, so when performing two-step press forming as in the conventional method, In comparison, the cost for the mold can be reduced, and as a result, an increase in the manufacturing cost of automobile panels can be suppressed. In addition, when press forming is performed in two stages, the yield of the final manufactured automobile panel decreases because a yield is generated for each stage. Since the region to be molded can be molded into the target shape, it is possible to suppress a decrease in the yield of manufactured automobile panels. Furthermore, when performing two-step press forming, there is a risk that the forming marks left on the blank material during the first step of press forming may remain on the final automobile panel. Since the area to be formed can be formed into the target shape in the forming process, it is possible to prevent forming marks from the first step of press forming from remaining on the automobile panel.

The inner surface of the recess includes a first inner surface portion that is disposed on one side with respect to the valley line portion and extends toward the punch side as the distance from the valley line portion increases; a second inner surface portion disposed on the opposite side to the first inner surface portion and extending toward the punch side as the distance from the valley line portion increases; the outer surface of the convex portion is disposed on one side with respect to the top portion; a first outer surface portion facing the first inner surface portion; and a second outer surface portion facing the second inner surface portion and disposed on the opposite side of the first outer surface portion with respect to the top portion; The top portion has a first protrusion portion that protrudes from the first outer surface portion toward the first inner surface portion, and a second protrusion portion that protrudes from the second outer surface portion toward the second inner surface portion; In the step, one of the die and the punch is brought close to the other such that the first protrusion bites into the first adjacent portion while the first adjacent portion is in contact with the first inner surface portion. The first adjacent portion is press-molded so that the thickness of the first adjacent portion is smaller than the predetermined thickness, and the second protrusion is formed with the second adjacent portion in contact with the second inner surface portion. Press-forming the second adjacent portion so that the thickness of the second adjacent portion is smaller than the predetermined thickness by moving one of the die and the punch closer to the other so as to bite into the second adjacent portion. It is preferable to do so.

In this way, the first and second protruding portions can reduce the thickness of the first and second adjacent portions from the back surface side opposite to the outer surface where the character line is formed in the molding target region of the blank material. It is possible to prevent marks from press molding from remaining on the outer surface of the automobile panel at positions adjacent to both sides of the character line.

As described above, according to the method for manufacturing an automotive panel of the present invention, a sharper character line can be formed, an increase in manufacturing cost and a decrease in the yield of manufactured automotive panels can be suppressed, and the manufacturing method can be improved. It is possible to prevent molding marks from remaining on the molded automobile panels.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional view schematically showing a manufacturing process of an automobile panel according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional view schematically showing a manufacturing process of an automobile panel according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional view schematically showing a manufacturing process of an automobile panel according to an embodiment of the present invention. FIG. 4 is an enlarged view of the vicinity of a character line formation location in FIG. 3; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional view schematically showing a manufacturing process of an automobile panel according to an embodiment of the present invention. 6 is an enlarged view of the vicinity of a character line formation location in FIG. 5. FIG. FIG. 2 is an enlarged view of a vertical cross section near the top of a convex portion of a punch and a valley line portion of a concave portion of a die opposing thereto used in the method for manufacturing an automobile panel according to an embodiment. FIG. 2 is a distribution diagram of equivalent plastic strain occurring in an automobile panel manufactured by a manufacturing method according to an example. FIG. 7 is an enlarged view of a vertical cross section near the top of a convex portion of a punch and a valley line portion of a concave portion of a die opposing thereto used in a method for manufacturing an automobile panel according to a comparative example. FIG. 3 is a distribution diagram of equivalent plastic strain occurring in an automobile panel manufactured by a manufacturing method according to a comparative example. FIG. 7 is an enlarged view of a longitudinal section near the top of a protrusion of a punch and a valley line of a recess of a die facing the top used in the method for manufacturing an automobile panel according to a first modification of the present invention. FIG. 7 is an enlarged view of a vertical cross section near the top of a convex portion of a punch and a valley line portion of a concave portion of a die opposing thereto used in a method for manufacturing an automobile panel according to a second modification of the present invention. FIG. 7 is an enlarged view of a longitudinal section near the top of a protrusion of a punch used in a method for manufacturing an automobile panel according to a third modification of the present invention and near a valley line of a recess of a die facing thereto.

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 and 5 schematically show the manufacturing process of an automobile panel 1 according to an embodiment of the present invention. 1 to 3 and FIG. 5, an automobile panel 1, a blank material 100 that is the material of the automobile panel 1, and a punch 10 and a die 20 that are molds for press-molding the automobile panel 1 are shown. , and a holder 30 for holding the blank material 100 are shown in a longitudinal section in a direction that intersects with a character line 2 formed on the automobile panel 1 and is along the pressing direction of the blank material 100. Further, FIG. 4 is an enlarged view of the vicinity of the character line forming point 103 in FIG. 3, and FIG. 6 is an enlarged view of the vicinity of the character line forming point 103 in FIG.

In the manufacturing method according to the present embodiment, a blank material 100 is press-molded to manufacture an automobile panel 1 (see FIG. 5) having a target shape and having a character line 2 that is a ridgeline. The shape of this automobile panel 1 is a shape that is bent with the character line 2 as the apex.

In the manufacturing method according to this embodiment, first, a punch 10 and a die 20 are prepared.

The punch 10 has a convex portion 11 having a shape corresponding to the target shape of the automobile panel 1. The convex portion 11 of the punch 10 is formed so that its width decreases toward the tip in its protruding direction, and has a top portion 12 that is the most protruding portion at the center in its width direction. Note that the width direction corresponds to a direction intersecting the character line 2 formed on the automobile panel 1 and perpendicular to the pressing direction, and corresponds to the left-right direction in each figure. The outer surface of the convex portion 11 has a first outer surface portion 14 and a second outer surface portion 16 .

The first outer surface portion 14 is located on one side with respect to the top portion 12 in the width direction. The first outer surface portion 14 is a slope that extends in the direction opposite to the protruding direction of the top portion 12 as it moves away from the top portion 12 to one side in the width direction. The first outer surface portion 14 faces the first inner surface portion 26 of the concave portion 22 of the die 20 in the direction along the press direction when the punch 10 and the die 20 are attached to the press forming apparatus as described later. It is arranged parallel to the first inner side surface portion 26 .

The second outer surface portion 16 is located on the opposite side of the first outer surface portion 14 with respect to the top portion 12 in the width direction. The second outer surface portion 16 is a slope that extends in the direction opposite to the protruding direction of the top portion 12 as it moves away from the top portion 12 to the side opposite to the first outer surface portion 14 in the width direction. This second outer surface portion 16 faces the second inner surface portion 27 of the recess 22 of the die 20 in the direction along the press direction when the punch 10 and the die 20 are attached to the press forming apparatus as described later. It is arranged parallel to the second inner side surface part 27.

The top portion 12 protrudes beyond the extension line of the first outer surface portion 14 and the second outer surface portion 16. Specifically, the top portion 12 has a first protruding portion 12a that protrudes from the first outer surface portion 14 toward the first inner surface portion 26 of the die 20 when the punch 10 and the die 20 are attached to the press molding apparatus as described later. and a second protrusion 12b that protrudes from the second outer surface 16 toward the second inner surface 27 of the die 20 in the same state. The first protruding part 12a is located on the first outer surface part 14 side with respect to the tip 12c which is the most protruding point of the top part 12, and the second protruding part 12b is located on the second outer surface part 16 with respect to the tip 12c. located on the side. Further, the entire outer surface of the top portion 12 is a curved surface having an arcuate cross-sectional shape.

The die 20 has a recess 22 having a shape corresponding to the target shape of the automobile panel 1 and roughly corresponding to the shape of the convex part 11 of the punch 10, and an outer peripheral part 24 located around the recess 22. .

The inner surface of the recess 22 has a valley line portion 25 , a first inner surface portion 26 , and a second inner surface portion 27 .

The trough line portion 25 is located at the bottom of the recess 22 at the center in the width direction of the recess 22, and when the punch 10 and die 20 are attached to the press forming apparatus as described later, the trough line portion 25 is located at the center of the recess 22 in the width direction. It is provided at a position facing the top portion 12 of the convex portion 11 of the punch 10 in the direction. Further, this valley line portion 25 faces a character line forming portion 103 of the blank material 100 in the pressing direction in a forming process described later.

The first inner side surface portion 26 is disposed on one side with respect to the valley line portion 25 in the width direction. This first inner side surface portion 26 is a slope that extends toward the opening side of the recessed portion 22 as it moves away from the valley line portion 25 to one side in the width direction. As described later, when the punch 10 and the die 20 are attached to the press molding device, the first inner side surface portion 26 extends toward the punch 10 as it moves away from the trough line portion 25 toward one side in the width direction. The first outer surface 14 of the punch 10 is disposed opposite to and parallel to the first outer surface 14 of the punch 10 in the direction along the pressing direction.

The second inner side surface portion 27 is disposed on the opposite side of the first inner side surface portion 26 with respect to the valley line portion 25 in the width direction. The second inner side surface portion 27 is a slope that extends toward the opening side of the recess 22 as it moves away from the valley line portion 25 toward the side opposite to the first inner side surface portion 26 in the width direction. As described later, when the punch 10 and the die 20 are attached to the press molding device, the punch 10 moves away from the valley line portion 25 toward the side opposite to the first inner surface portion 26 in the width direction. In this state, it is disposed opposite to and parallel to the second outer surface portion 16 of the punch 10 in the direction along the pressing direction. The second inner surface portion 27 is connected to the first inner surface portion 26 at the valley line portion 25 .

In the manufacturing method according to the first embodiment, the punch 10 and die 20 configured as described above are mounted on a press molding device (not shown). At this time, the die 20 and the punch 10 are arranged vertically separately, and the die 20 is arranged with the concave part 22 facing downward, and the punch 10 is arranged with the convex part 11 facing upward, and the convex part 11 is It is placed directly below the recess 22 of the die 20 (see FIG. 1). More specifically, the punch 10 is arranged with respect to the die 20 so that the tip 12c (apex) of the top 12 of the convex portion 11 is located directly below the valley line portion 25 of the concave portion 22. At this time, the first inner side surface 26 of the die 20 is arranged parallel to the first outer side surface 14 of the punch 10 and is spaced apart from the first outer side surface 14 in the direction along the pressing direction (vertical direction). and is arranged so as to face the first outer surface portion 14 thereof. Further, the second inner side surface 27 of the die 20 is arranged parallel to the second outer side surface 16 of the punch 10 and is spaced apart from the second outer side surface 16 in the direction along the press direction (vertical direction). It is arranged so as to face the second outer side surface portion 16 thereof. Further, the punch 10 is arranged in such a manner that the central axis of the convex portion 11 thereof is along the pressing direction by the press molding device.

Next, as shown in FIG. 1, a holding process is performed in which the blank material 100 is held by the holder 30. In this holding step, the holder 30 holds the peripheral part 102 around the forming target area 101, which is the area of the blank material 100 that is to be formed into the target shape. In this holding step, the peripheral portion 102 of the blank material 100 is placed against the die 20 with the blank material 100 arranged so that the region 101 to be formed of the blank material 100 faces the recess 22 of the die 20. It is held by fixing it with the holder 30.

Specifically, the blank material 100 is a flat plate made of metal such as aluminum or steel. In the holding step, the region 101 to be formed of the blank material 100 is located directly below the concave portion 22 of the die 20 and is placed above the convex portion 11 of the punch 10 so as to face the convex portion 11, and in this state, the blank is A peripheral portion 102, which is a portion of the material 100 located around the molding target region 101, is held by being sandwiched between the holder 30 and the outer peripheral portion 24 of the die 20. Thereby, the peripheral portion 102 is fixed to the die 20. The holding force of the peripheral part 102 between the die 20 and the holder 30 is such that when the forming target area 101 of the blank material 100 is pressed by the punch 10 and bent and deformed in the forming process described later, the peripheral part 102 is This is a force large enough to prevent the movement of the material inward in the width direction.

Next, a molding step is performed in which the region 101 to be molded of the blank material 100 is press-molded into the target shape.

In this forming process, the die 20 is lowered toward (approaches) the punch 10 by the press forming apparatus. As shown in FIG. The character line forming portion 103, which is the portion where the character line 2 is formed, is bent and deformed as the vertex. In the process of this bending deformation, the region to be formed 101 and the convex portion 11 of the punch 10 enter into the concave portion 22 of the die 20 .

Then, as shown in FIG. 3, the die 20 further descends and approaches the punch 10, and the bending-deformed region 101 to be formed comes into contact with the inner surface of the recess 22 of the die 20. At this point, as shown in FIG. A second adjacent portion 106 which is sandwiched between the inner surface portion 26 and adjacent to the character line forming portion 103 on the other side of the molding target region 101 is located between the top 12 of the punch 10 and the second concave portion 22 of the die 20 . It is sandwiched between the inner side surface portion 27 and the inner side surface portion 27 . Specifically, the first adjacent portion 104 is sandwiched between the first protruding portion 12a of the top portion 12 and the first inner surface portion 26 of the recess 22, and the second adjacent portion 106 is sandwiched between the second protruding portion 12b of the top portion 12. and the second inner side surface 27 of the recess 22 . At this point, a portion of the molding target region 101 between the first adjacent portion 104 and the second adjacent portion 106 is separated from the inner surface of the recess 22 of the die 20. In other words, a portion of the molding target area 101 near the character line formation location 103 between the first adjacent location 104 and the second adjacent location 106, and a portion of the inner surface of the recess 22 near the valley line portion 25. A gap remains between them.

Thereafter, at the end of the forming process, as shown in FIG. The distance between the first inner surface portion 26 and the distance between the outer surface of the second protruding portion 12b of the top portion 12 and the second inner surface portion 27 in the direction perpendicular to the second inner surface portion 27 of the recess 22 is blank. The die 20 approaches the punch 10 until the thickness of the material 100 becomes smaller than the original predetermined thickness, and the die 20 reaches the bottom dead center.

At the end of this forming process, as shown in FIG. Points 104 and 106 are press formed between the top 12 of the punch 10 and the inner surface of the recess 22 of the die 20. Specifically, the first adjacent portion 104 is located between the first protruding portion 12a of the top portion 12 and the first inner side surface portion 26 of the recessed portion 22 such that the thickness of the first adjacent portion 104 is smaller than the original thickness. Press-molded. That is, with the first adjacent portion 104 in contact with the first inner surface portion 26, the first protrusion 12a is pressed so as to bite into the first adjacent portion 104, and the thickness of the first adjacent portion 104 is reduced. Further, the second adjacent portion 106 is press-formed between the second protruding portion 12b of the top portion 12 and the second inner side surface portion 27 of the recessed portion 22 so that the thickness of the second adjacent portion 106 is smaller than the original thickness. be done. That is, with the second adjacent portion 106 in contact with the second inner side surface portion 27, the second protruding portion 12b is pressed so as to bite into the second adjacent portion 106, and the thickness of the second adjacent portion 106 is reduced.

As a result of the decrease in the thickness of the first and second adjacent portions 104 and 106, the material corresponding to the decreased thickness of those portions is transferred to the area between the first adjacent portion 104 and the second adjacent portion 106. Flow. As a result, the part near the character line forming part 103 is molded so that the gap between the part near the character line forming part 103 of the molding target area 101 and the part near the valley line part 25 on the inner surface of the recess 22 is filled, A character line 2 is formed on the outer surface of the character line forming location 103.

The above molding process is performed continuously. That is, the die 20 is continuously lowered until it reaches the bottom dead center, and the region 101 to be molded is continuously molded until it becomes the target shape having the character line 2.

As described above, the method for manufacturing the automotive panel 1 according to the present embodiment is carried out.

In the manufacturing method according to the present embodiment, in the molding process, the first adjacent part 104 and the second adjacent part 106 on both sides of the character line forming part 103 in the molding target area 101 of the blank material 100 are connected to the inner surface of the recess 22 of the die 20. Since the material is sandwiched between the punch 10 and the top 12 of the punch 10, the material near the character line forming area 103 in the forming area 101 is suppressed from flowing to the outside of the first and second adjacent areas 104 and 106, thereby forming the character line. It is possible to suppress thinning of the wall near the location.

Furthermore, in the manufacturing method according to the present embodiment, after the first adjacent portion 104 and the second adjacent portion 106 are sandwiched between the inner surface of the recess 22 and the top portion 12 as described above, the first and second adjacent portions 106 . The material whose thickness has been reduced can be made to flow near the character line forming point 103 between the adjacent points 104 and 106 to compensate for the thickness near the character line forming point 103. As a result, the thickness near the character line forming point 103 can be compensated for. A sharper character line 2 can be formed by suppressing flattening of the outer surface in the vicinity.

Moreover, in the manufacturing method according to the present embodiment, the forming target region 101 of the blank material 100 can be formed into the target shape having the character line 2 by one continuous press forming (forming process). Therefore, the cost for the mold can be reduced compared to the conventional two-stage press forming, and as a result, an increase in the manufacturing cost of the automobile panel 1 can be suppressed.

Furthermore, when press forming is performed in two stages, the yield of the final manufactured automobile panel 1 decreases because the yield is increased for each stage. Since the automotive panel 1 can be manufactured by molding the molding target region 101 into the target shape by press molding, a decrease in the yield of the automotive panel 1 can be suppressed.

Furthermore, when performing two-step press forming, there is a risk that forming marks on the blank material in the first step of press forming may remain on the automobile panel 1 to be finally manufactured, but the manufacturing method according to the present embodiment In this case, since the automotive panel 1 can be manufactured by molding the molding target region 101 into the target shape in one continuous press molding, it is possible to prevent molding marks from remaining on the automotive panel 1.

In addition, in the manufacturing method according to the present embodiment, at the end of the forming process, the first protruding portion 12a of the top portion 12 of the punch 10 is in contact with the first inner surface portion 26 of the die 20 while the first adjacent portion 104 is in contact with the first inner surface portion 26 of the die 20. By moving the die 20 closer to the punch 10 so as to bite into the adjacent portion 104, the first adjacent portion 104 is press-formed so that the thickness of the first adjacent portion 104 is smaller than the original predetermined thickness, and The die 20 is brought closer to the punch 10 so that the second protruding portion 12b of the top portion 12 of the punch 10 bites into the second adjacent portion 106 while the second adjacent portion 106 is in contact with the second inner side surface portion 27 of the die 20. The second adjacent portion 106 is press-molded so that the thickness of the second adjacent portion 106 is smaller than the original predetermined thickness. Therefore, the first and second protrusions 12a and 12b cover the first and second adjacent portions 104 and 106 from the back side of the forming target region 101 of the blank material 100, which is opposite to the outer surface where the character line 2 is formed. Press molding can be performed so that their thickness is reduced, and it is possible to prevent marks from press molding from remaining on the outer surface of the automobile panel 1 at positions adjacent to both sides of the character line 2.

Next, a simulation will be described in which the effects of the manufacturing method of this embodiment were investigated.

Specifically, in this simulation, it was investigated how distortion would occur near the character line 2 (character line formation location 103) in the automobile panel 1 manufactured by the manufacturing method of the present embodiment.

In this simulation, as an example, a case is set in which an automobile panel 1 is manufactured in a process similar to the above-described manufacturing method using the same punch 10 and die 20 used in the above-described manufacturing method according to the present embodiment. did. FIG. 7 shows the configuration of the vicinity of the top 12 of the convex portion 11 of the punch 10 used in this embodiment and the vicinity of the trough line portion 25 of the concave portion 22 of the die 20 opposing thereto.

In addition, as a comparative example, a punch having a shape commonly used in the past, specifically, as shown in FIG. After using a punch 210 having a top 212 that does not protrude further than the top 212 of the punch 210 and bending and deforming the region to be formed of the blank material, the point in time when the region to be formed contacts the inner surface of the recess 222 of the die 220. A case was set in which an automobile panel 201 (see FIG. 10) was manufactured in the same manner as the above-described manufacturing method of the embodiment, except that the molding process was ended at .

Then, the strain in the tensile direction, specifically equivalent plastic strain, that occurs in the automotive panels produced in each of the examples and comparative examples was investigated by simulation. FIG. 8 shows the equivalent plastic strain distribution of the automotive panel 1 of the example obtained by the simulation. Further, FIG. 10 shows the equivalent plastic strain distribution of the automotive panel 201 of the comparative example obtained by the simulation.

In the comparative example (see FIG. 10), considerable plastic strain occurs in the range β extending on both sides of the character line forming location 203 in the automobile panel 201. This distortion occurs when the character line forming portion 203 is formed at the top 212 of the punch 210 (see FIG. This is caused by the bending deformation of the molding target area 221 when pressed against the character line forming area 203, and is considered to be a strain in the tensile direction from the character line forming location 203 to both outer sides in the width direction. As a result of this distortion, the area around the character line forming area 203 becomes thinner, and the outer surface of the area around the character line forming area 203 becomes flattened, thereby reducing the sharpness of the character line 202 formed on the automobile panel 201. It is declining.

On the other hand, in the example, as shown in FIG. 8, considerable plastic strain occurs in the range α1 extending on both sides of the character line forming location 103 in the automobile panel 1, but in the inner range of the range α1. Particularly large distortion occurs in α2. This range α2 is a range extending from the first adjacent portion 104 to the second adjacent portion 106 in the molding target region 101. The reason for the large distortion in this range α2 is that the first and second adjacent parts 104 and 106 are located between the top 12 of the punch 10 and the inner surface of the recess 22 of the die 20 at the end of the forming process. Press molding is performed so that the thickness of the two adjacent parts 104, 106 is smaller than the original predetermined thickness, so that the material corresponding to the reduced thickness of the first and second adjacent parts 104, 106 forms the character line. This is thought to be due to the flow toward the formation location 103. In this example, as in the comparative example, thinning occurs near the character line forming area 103 due to strain in the tensile direction caused by bending deformation of the molding target area 101. Nearby thickness is compensated. As a result, the flattening of the outer surface in the vicinity of the character line formation location 103 is suppressed, and the character line 2 is formed more sharply.

(Modified example)
The method of manufacturing an automobile panel according to the present invention is not necessarily limited to the above method. For example, the following techniques can be employed in the method of manufacturing an automobile panel according to the present invention.

Specifically, the shape of the top of the punch used in the manufacturing method according to the present invention is not necessarily limited to the shape of the top 12 in the above embodiment, and in the forming process, the forming target area 101 of the blank material 100 is The character line forming area 103 can be bent and deformed with the apex being the apex, and at the end of the forming process, the thickness of the first adjacent area 104 and the second adjacent area 106 on both sides of the character line forming area 103 is the same as the original thickness of the blank material 100. Any shape may be adopted as long as it is possible to press-form the first adjacent portion 104 and the second adjacent portion 106 so that the thickness thereof is smaller than the thickness of the first adjacent portion 104 and the second adjacent portion 106 . 11 to 13 show the shape of the top 12 of the punch 10 used in the manufacturing method according to each modification of the present invention, and the top of the punch 10 when the die 20 reaches the bottom dead center. 12 and a portion of the die 20 that faces the top 12 of the punch 10 are partially shown.

In the first modification shown in FIG. 11, a tip region 12d, which is a region near the center in the width direction (near the tip 12c) of the top 12 of the punch 10, has an arcuate cross-sectional shape with a large radius of curvature. The first protruding portion 12a and the second protruding portion 12b on both sides of the tip region 12d of the top portion 12 have an arcuate cross-sectional shape having a radius of curvature smaller than the radius of curvature of the outer surface of the tip region 12d. Each has an outer surface of

Furthermore, in the second modification shown in FIG. 12, the tip end surface 17 of the top portion 12 of the punch 10 is flat.

Further, in the third modification shown in FIG. 13, the surface 18 of the first protruding portion 12a of the top portion 12 that faces the first inner surface portion 26 of the recess 22 of the die 20 is generally similar to the first outer surface portion 14. The surface 19 of the second protrusion 12b of the top portion 12, which faces the second inner side surface 27 of the recess 22 of the die 20, has an inclination angle that is approximately the same as that of the second outer side surface 16. It is a slope with a

In any of the punches 10 according to the first to third modifications as described above, the first protruding portion 12a of the top portion 12 protrudes from the first outer surface portion 14 toward the first inner surface portion 26 of the die 20, and the first protruding portion 12a of the top portion 12 Two protruding portions 12b protrude from the second outer surface portion 16 toward the second inner surface portion 27 of the die 20. Even when the punch 10 according to the first to third modified examples is used, at the end of the forming process (when the die 20 reaches the bottom dead center), the first part of the recess 22 of the die 20 the distance between its first inner surface 26 and the outer surface of the first protrusion 12a of the top 12 of the punch 10 in a direction perpendicular to the inner surface 26 and the second inner surface 27 of the recess 22 of the die 20; The distance between its second inner side 27 in the direction and the outer surface of the second protrusion 12b of the top 12 of the punch 10 is smaller than the original predetermined thickness of the blank 100. Therefore, at the end of the molding process, the thickness of the first adjacent part 104 and the second adjacent part 106 on both sides of the character line forming part 103 in the molding target area 101 of the blank material 100 is smaller than the original predetermined thickness of the blank material 100. The first adjacent portion 104 and the second adjacent portion 106 can be press-molded so that the first adjacent portion 104 and the second adjacent portion 106 are also smaller.

Further, the first outer surface portion 14 of the convex portion 11 of the punch 10 is not necessarily parallel to the first inner surface portion 26 of the recessed portion 22 of the die 20 when the punch 10 and the die 20 are attached to the press forming apparatus. It does not have to have an inclination angle, and may have a different inclination angle from the first inner side surface part 26. Similarly, the second outer side surface 16 of the convex portion 11 of the punch 10 is not necessarily parallel to the second inner side surface 27 of the recess 22 of the die 20 when the punch 10 and the die 20 are attached to the press forming apparatus. It does not have to have such an inclination angle, and may have a different inclination angle from the second inner side surface portion 27.

Furthermore, in the method for manufacturing the automobile panel 1, at the end of the forming process, the first and second adjacent parts 104 and 106 of the forming target area 101 of the blank material 100 are formed so that the thickness thereof becomes smaller than the original thickness. As a result of press forming between the inner surface of the recess 22 of the die 20 and the top 12 of the punch 10, the outer surface of the first adjacent portion 104 is strongly pressed against the first inner surface portion 26 of the recess 22 of the die 20, and The outer surface of the location 106 is strongly pressed against the second inner surface portion 27 of the recess 22 of the die 20 . As a result, it is conceivable that contact marks with the die 20 may remain at positions adjacent to the character line 2 on both sides of the outer surface of the molded automobile panel 1. As a countermeasure, a portion of the first inner surface portion 26 of the die 20 that contacts the first adjacent portion 104 of the blank material 100 and a portion of the second inner surface portion 27 of the die 20 that contacts the second adjacent portion 106 of the blank material 100. A cushioning material, such as a rubber sheet, may be installed in each of these areas, and the cushioning material may suppress the formation of contact marks as described above.

In addition, in the forming process, instead of the die 20 approaching the punch 10 whose position is fixed, the punch 10 approaches the die 20 whose position is fixed, and the convex portion 11 is used to form the blank material 100. The region 101 may be bent and deformed.

Further, the moving direction of the die 20 or the punch 10 in the forming process is not necessarily limited to the vertical direction, but may be set in any direction.

Further, the die 20 is arranged with the concave part 22 facing upward, and the punch 10 is arranged with the convex part 11 facing downward, and the convex part 11 is located directly above the concave part 22. Good too.

1 Automotive panel 2 Character line 10 Punch 11 Convex portion 12 Top portion 12a First protruding portion 12b Second protruding portion 14 First outer surface portion 16 Second outer surface portion 20 Die 25 Valley line portion 26 First inner surface portion 27 Second inner surface portion 30 Holder 100 Blank material 101 Molding target area 102 Peripheral area 103 Character line formation location

Claims (2)

A method for manufacturing an automobile panel in a target shape having character lines by press-forming a plate-shaped blank material having a predetermined thickness, the method comprising:
The blank material is arranged between a die having a concave portion and a punch having a convex portion arranged to face the concave portion, and a peripheral portion of the blank material around a region to be formed into the target shape. a holding step of holding with a holder;
a molding step of molding the region to be molded into the target shape between the concave portion and the convex portion by bringing one of the die and the punch closer to the other;
The inner surface of the recess has a valley line portion provided at the bottom of the recess at a position facing the top of the protrusion,
In the forming step, the region to be formed is pressed against the top , and the region to be formed is bent and deformed with the character line formation location where the character line is formed as the vertex, and the bending and deformation is performed. A first adjacent location adjacent to the character line forming location on one side of the target area and a second adjacent location adjacent to the character line forming location on the opposite side of the first adjacent location are arranged in the recessed portion. sandwiched between the inner surface and the top of the convex portion, and at the time of the sandwiching, a gap is left between the character line forming location and the valley line portion of the inner surface of the concave portion; Thereafter , the first adjacent portion and the second adjacent portion are connected to the inner surface of the recess and the top portion such that the thickness of both the first adjacent portion and the second adjacent portion is smaller than the predetermined thickness. By press-forming between the parts, the material corresponding to the reduced thickness flows into the area between the first adjacent part and the second adjacent part, and the thickness of the character line forming part is compensated for. A method for manufacturing an automotive panel. The inner surface of the recess includes a first inner surface portion that is disposed on one side with respect to the valley line portion and extends toward the punch side as the distance from the valley line portion increases; a second inner side surface that is disposed on the opposite side to the first inner side surface and extends toward the punch side as it moves away from the trough line;
The outer surface of the convex portion includes a first outer surface portion disposed on one side with respect to the top portion and facing the first inner surface portion, and a first outer surface portion disposed on the opposite side of the first outer surface portion with respect to the top portion. having a second inner surface portion and an opposing second outer surface portion;
The top portion has a first protrusion that protrudes from the first outer surface toward the first inner surface, and a second protrusion that protrudes from the second outer surface toward the second inner surface,
In the forming step, one of the die and the punch is brought close to the other such that the first protrusion bites into the first adjacent portion while the first adjacent portion is in contact with the first inner side surface portion. The first adjacent portion is press-molded so that the thickness of the first adjacent portion is smaller than the predetermined thickness, and the second protrusion is formed while the second adjacent portion is in contact with the second inner surface portion. the second adjacent portion so that the thickness of the second adjacent portion is smaller than the predetermined thickness by causing one of the die and the punch to approach the other such that the portion bites into the second adjacent portion; The method for manufacturing an automobile panel according to claim 1, comprising press molding.

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