JP2017170506A - Manufacturing method of panel-like formed product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a panel-like formed product which is difficult to form, and has high-strength with less defective such as a wrinkle.SOLUTION: A manufacturing method includes a preparation process, an intermediate pressing process, and a pressing process. In the preparation process, a blank material formed of a metal plate is prepared. In the intermediate pressing process, the blank material is cold-pressed to obtain an intermediate formed product 1A. In the pressing process, the intermediate formed product 1A is pressed to obtain a panel-like formed product 1. In the pressing process, a press device 10 including a first die 12, a second die 13, a punch 11, and a blank hole 14 is used. The panel-like formed product 1 is formed by relatively moving the second die 13 and the blank holder 14 with respect to the first die 12 and the punch 11 with the intermediate formed product 1A sandwiched by the first die 12 and the punch 11.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for producing a panel-shaped molded article. More specifically, the present invention relates to a method for manufacturing a panel-shaped molded article suitable for an automobile door inner panel.

  An automobile door is manufactured by combining a door inner panel and a door outer panel. A window, a window driving device, an acoustic speaker, a handle, and the like are attached to the door of the automobile. In order to store them between the door inner panel and the door outer panel, it is necessary to provide a space. In order to provide the space, for example, a vertical wall portion is provided on the door inner panel. In addition, it is necessary to seal the interior of the vehicle when the door of the vehicle is closed. In order to seal the interior of the vehicle, for example, a step portion is provided on the door inner panel. The part of the vertical wall provided with the stepped portion is made to face a pillar or the like to enhance the sealing performance in the vehicle.

  Door inner panels used for automobile side doors and the like are formed by pressing a metal plate such as a steel plate. In general, the shape of the door inner panel is complicated. Therefore, the metal plate may be greatly deformed. In this case, the door inner panel after press working may be cracked or wrinkled. In particular, when the door inner panel has a step portion and an adjacent vertical wall portion, the door inner panel after press working is likely to be cracked and wrinkled.

  In order to eliminate this inconvenience, a metal plate having high workability is often used as the material (blank material) of the door inner panel. Since a highly workable metal plate has high ductility, even if the material is deformed, cracks, wrinkles and the like are unlikely to occur.

  A method for producing a panel-shaped molded article including a door inner panel is disclosed in International Publication No. 2014/084151 (Patent Document 1).

  The manufacturing method of the panel-shaped molded product disclosed in Patent Document 1 includes a vertical wall portion forming step and a flange portion forming step. In the vertical wall portion forming step, the blank material is pressed with a punch and a die to form the entire vertical wall portion. In the flange portion forming step, which is a subsequent process, the flange portion is formed with the top plate portion sandwiched between the pad and the punch and the vertical wall portion sandwiched between the punch and the die. In the vertical wall portion forming step, since the end portion of the blank material is not constrained, the spring back of the vertical wall portion hardly occurs. Patent Document 1 discloses that in the flange portion forming step, the top plate portion and the vertical wall portion are constrained by a mold, so that the flange portion can be formed with high accuracy.

International Publication No. 2014/084151

  However, in the manufacturing method of Patent Document 1, when a shape having a high degree of molding difficulty is formed, cracks, wrinkles, and the like may occur. The shape having a high degree of molding difficulty referred to here is a shape or the like in which a panel-shaped molded product after press working has a step portion and an adjacent vertical wall portion.

  An object of the present invention is to provide a method for producing a high-strength panel-like molded product with few defects such as cracks and wrinkles even if the shape is highly difficult to mold.

  The manufacturing method of the panel-shaped molded product by embodiment of this invention is applied to manufacture of the panel-shaped molded product which has a top-plate part, a vertical wall part, and a level | step difference part. The top plate is polygonal. The vertical wall portion extends from at least two sides of the top plate portion. A level | step difference part is provided in each vertical wall part of at least 1 set of the group of the adjacent vertical wall part among vertical wall parts.

  The manufacturing method includes a preparation process, an intermediate press process, and a press process. In the preparation step, a blank material made of a metal plate is prepared. In the intermediate pressing process, the blank material is pressed in a cold state. Thus, an intermediate molded product is obtained in which the top plate portion is formed and the vertical wall portion is formed to the height of the stepped portion. In the pressing process, the intermediate molded product is pressed in the cold. Thereby, a panel-shaped molded product is obtained.

  In the press working step, a press device including a first die, a second die, a punch, and a blank holder is used. The shape of the first die is formed up to the outer edges of the top plate portion and the step portion. The second die is disposed outside the first die. The punch faces the first die, and the shape of the top plate portion and the step portion is formed. The blank holder faces the second die. In a state where the intermediate molded product is sandwiched between the first die and the punch, the second die and the blank holder are moved relative to the first die and the punch to form a panel-shaped molded product.

  The method for producing a panel-shaped molded product according to the present invention can obtain a panel-shaped molded product having a high strength with few defects such as cracks and wrinkles, even if the molding difficulty is high.

FIG. 1 is a perspective view of a door inner panel formed by the manufacturing method of the first embodiment. FIG. 2A is a perspective view showing a situation after the intermediate press working step. FIG. 2B is a perspective view showing a situation during the press working process. FIG. 2C is a perspective view showing a situation after the press working process. FIG. 3 is a cross-sectional view schematically showing a pressing device used in the pressing process of the first embodiment. FIG. 4A is a cross-sectional view showing a stage in which the intermediate molded product of the first embodiment is arranged in a press device. FIG. 4B is a cross-sectional view illustrating a stage in which the intermediate molded product is sandwiched between the first die and the punch. FIG. 4C is a cross-sectional view showing a stage (bottom dead center) when the lowering of the second die is completed. FIG. 5 is a cross-sectional view showing a state during pressing by a conventional pressing apparatus. FIG. 6 is a perspective view schematically showing a door inner panel formed by the manufacturing method of the second embodiment. FIG. 7A is a perspective view showing the situation after the intermediate press working step. FIG. 7B is a perspective view showing a situation during the press working process. FIG. 7C is a perspective view illustrating a state after the press working process. FIG. 8A is a cross-sectional view showing a stage in which the intermediate molded product of the second embodiment is arranged in the press device. FIG. 8B is a cross-sectional view showing a stage in which the intermediate molded product is sandwiched between the first die and the punch. FIG. 8C is a cross-sectional view showing a stage (bottom dead center) when the lowering of the second die is completed. FIG. 9 is a cross-sectional view showing a state during pressing by a conventional pressing apparatus. FIG. 10A is a cross-sectional view showing a stage in which the intermediate molded product of the third embodiment is arranged in a press device. FIG. 10B is a cross-sectional view showing a stage in which the intermediate molded product is sandwiched between the first die and the punch. FIG. 10C is a cross-sectional view showing a stage (bottom dead center) when the lowering of the second die is completed.

  The manufacturing method of the panel-shaped molded product by embodiment of this invention is applied to manufacture of the panel-shaped molded product which has a top-plate part, a vertical wall part, and a level | step difference part. The top plate is polygonal. The vertical wall portion extends from at least two sides of the top plate portion. A level | step difference part is provided in each vertical wall part of at least 1 set of the group of the adjacent vertical wall part among vertical wall parts.

  The manufacturing method includes a preparation process, an intermediate press process, and a press process. In the preparation step, a blank material made of a metal plate is prepared. In the intermediate pressing process, the blank material is pressed in a cold state. Thus, an intermediate molded product is obtained in which the top plate portion is formed and the vertical wall portion is formed to the height of the stepped portion. In the pressing process, the intermediate molded product is pressed. Thereby, a panel-shaped molded product is obtained.

  In the press working step, a press device including a first die, a second die, a punch, and a blank holder is used. The shape of the first die is formed up to the outer edges of the top plate portion and the step portion. The second die is disposed outside the first die. The punch faces the first die, and the shape of the top plate portion and the step portion is formed. The blank holder faces the second die. In a state where the intermediate molded product is sandwiched between the first die and the punch, the second die and the blank holder are moved relative to the first die and the punch to form a panel-shaped molded product.

  The manufacturing method of the panel-shaped molded product of the present embodiment can be manufactured by cracking the panel-shaped molded product having a high degree of molding difficulty and suppressing defects such as wrinkles. As described above, the shape having a high degree of molding difficulty is a shape having a stepped portion on the adjacent vertical wall portion of the panel-shaped molded product.

  Preferably, the manufacturing method may have the following configuration (1) or (2).

  (1) The top plate portion of the panel-shaped molded product has a recess. In the intermediate press working step, the raised portion is formed at a position corresponding to the concave portion of the panel-shaped molded product in the region of the top plate portion of the intermediate molded product. In the pressing process, the first die has an opening at a position corresponding to the raised portion of the intermediate molded product. The second die has a protrusion at a position corresponding to the opening of the first die. The region of the raised portion of the intermediate molded product is pressed into the concave portion of the panel-shaped molded product by the protrusion.

  (2) The top plate portion of the panel-shaped molded product has a convex portion. In the intermediate press working step, the depressed portion is formed at a position corresponding to the convex portion of the panel-shaped molded product in the region of the top plate portion of the intermediate molded product. In the press working process, the punch has an opening disposed at a position corresponding to the depressed portion of the intermediate molded product and a protrusion disposed at a position corresponding to the opening. The region of the depressed portion of the intermediate molded product is pressed into the convex portion of the panel-shaped molded product by the protrusion.

  Thereby, even if it forms a recessed part or a convex part in a top-plate part, the crack of a panel-shaped molded product, wrinkles, etc. can be suppressed.

  Preferably, the tensile strength of the panel-shaped molded article after the press working step is 390 MPa or more and 980 MPa or less. In this case, the panel-shaped molded product is suitable for an automobile door inner panel. Moreover, the above-mentioned metal plate can be made into a tailored blank. In this case, the collision characteristics of the door inner panel can be improved, and the weight of the door inner panel can be further reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated. In the present embodiment, as an example, the case where the panel-shaped molded article is made of a steel plate and is an automobile door inner panel will be described.

[First Embodiment]
[Molding]
FIG. 1 is a perspective view of a door inner panel formed by the manufacturing method of the first embodiment to be described later. With reference to FIG. 1, the door inner panel 1 includes a top plate portion 2, a vertical wall portion 4, and a step portion 5. The top plate 2 is a polygon. The shape of the top plate 2 may be, for example, a quadrangle or a pentagon. The polygonal apex of the top plate 2 may be R-shaped. In FIG. 1, the case where the top plate part 2 is a pentagon is shown as an example. In the door inner panel 1, one side of the top plate portion 2 forms a belt line BL.

  The vertical wall portion 4 extends from at least two sides of the top plate portion 2. In FIG. 1, the case where the vertical wall part 4 is extended from the four sides 2A, 2B, 2C and 2D of the pentagonal top plate part 2 is shown as an example. However, the number of sides of the top plate 2 where the vertical wall 4 extends is not limited to four. The vertical wall portion 4 only needs to extend from each side of two or more adjacent sides of the top plate portion 2. When the vertical wall portion 4 extends from two or more adjacent sides of the top plate portion 2, the vertical wall portions extending from each side are also adjacent. In FIG. 1, as an example, the vertical wall portion 4 extends perpendicularly to the top plate portion 2. However, the vertical wall portion 4 may not be strictly perpendicular to the top plate portion 2.

  The step portion 5 extends from the vertical wall portion 4 </ b> A connected to the top plate portion 2 to the outside of the top plate portion 2. The outer edge of the stepped portion 5 is connected to the vertical wall portion 4B connected to the flange portion 6. In FIG. 1, as an example, the surface of the step portion 5 is shown to be parallel to the top plate portion 2. However, the surface of the stepped portion 5 may not be strictly parallel. In FIG. 1, as an example, a case where three adjacent vertical wall portions 4 have stepped portions 5 is shown. However, the number of the vertical wall portions 4 having the step portions 5 is not limited to three. It is sufficient that two or more adjacent vertical wall portions 4 have the step portions 5. In other words, at least one set of the adjacent vertical wall portions 4 only needs to have the stepped portion 5. In FIG. 1, as an example, the case where the stepped portion 5 has one stage is shown. However, the number of steps of the step portion 5 is not limited to one. The vertical wall portion 4 may have a plurality of step portions 5.

  A door inner panel having a vertical wall portion extending from the side of the top plate portion and having a step portion in at least one pair of adjacent vertical wall portions is highly difficult to form. Therefore, defects such as cracks and wrinkles are likely to occur during press working. Conventionally, when processing a molded product having a complicated shape, a low-strength steel plate having high ductility has been pressed, so that the impact characteristics are low. By applying the method for producing a panel-shaped molded product of the present embodiment, even if the molded product has a high strength of 390 MPa or more and 980 MPa or less, the door inner panel having a high molding difficulty level is cracked and wrinkled. It is possible to mold while suppressing such defects.

  Here, the lower limit of the tensile strength of the door inner panel is defined from the viewpoint of collision characteristics. In order to ensure the collision characteristics of the door inner panel, the tensile strength of the door inner panel is preferably 390 MPa or more. However, the lower limit of the tensile strength of the door inner panel is not limited to 390 MPa. The manufacturing method of this embodiment is applicable also to manufacture of a door inner panel whose tensile strength is lower than 390 MPa. In short, there is no problem even if the tensile strength of the door inner panel is lower than 390 MPa if the collision characteristics are ensured by a reinforcing member or the like. The reinforcing member is, for example, a door impact beam.

  On the other hand, the upper limit of the tensile strength of the door inner panel is defined from the viewpoint of formability. In order to ensure cold formability, the door inner panel preferably has a tensile strength of 980 MPa or less. If the tensile strength of the door inner panel is higher than 980 MPa, the door inner panel is likely to be cracked or wrinkled. More preferably, the upper limit of the tensile strength of the door inner panel formed by the manufacturing method of the present embodiment is 780 MPa, and more preferably 590 MPa.

[Production method]
The manufacturing method of the first embodiment includes a preparation process, an intermediate press working process, and a press working process. After forming the intermediate molded product in the intermediate press working process, the intermediate molded product is formed on the door inner panel in the press working process.

  2A to 2C are views showing a molding process of the door inner panel manufactured in the first embodiment. FIG. 2A shows the situation after the intermediate press working step. FIG. 2B shows the situation during the pressing process. FIG. 2C shows the situation after the pressing process. Hereinafter, each process is demonstrated with reference to FIG. 2A-FIG. 2C.

[Preparation process]
In the preparation step, a blank material made of a steel plate is prepared. The blank material is obtained, for example, by cutting a steel plate into a desired dimension.

[Intermediate press working process]
In the intermediate press process, the blank material is pressed in a cold state to obtain an intermediate molded product. Specifically, in the intermediate press working step, the blank material is cold-drawn with a general press device.

  As shown in FIG. 2A, in the intermediate press working step, an intermediate molded product 1A having a top plate portion 2, a vertical wall portion 4A, and a flange portion 6A is obtained. The flange portion 6A is formed into a step portion 5 and a flange portion 6 (see FIG. 2C) in a later process. Therefore, the vertical wall portion 4A formed in the intermediate press working step is formed to the height of the step portion 5 (see FIG. 2C) of the product.

[Pressing process]
In the pressing process, the intermediate molded product is formed into a door inner panel using the following pressing device in the cold state.

  FIG. 3 is a cross-sectional view schematically showing a pressing device used in the pressing process of the first embodiment. With reference to FIG. 3, the press device 10 includes a punch 11, a first die 12, a second die 13, and a blank holder 14.

  The punch 11 includes a tip surface 11A and a step surface 11B. 11 A of front end surfaces form the shape of the top-plate part 2 of a door inner panel. The step surface 11B is formed with the shape of the step portion 5 of the door inner panel 1. The height from the step surface 11B to the tip surface 11A corresponds to the height from the step portion 5 to the top plate portion 2 of the door inner panel 1.

  The blank holder 14 is disposed adjacent to the outside of the punch 11. The blank holder 14 has a tip surface 14A. The blank holder 14 can be moved up and down by a driving device (not shown). The front end surface 14 </ b> A of the blank holder 14 faces the reference surface 13 </ b> A of the second die 13. The blank holder 14 sandwiches the intermediate molded product 1 </ b> A with the reference surface 13 </ b> A of the second die 13.

  The first die 12 includes a mold bottom surface 12A and a tip surface 12B. The mold bottom surface 12 </ b> A faces the tip surface 11 </ b> A of the punch 11. The shape of the top plate portion of the door inner panel is formed on the mold bottom surface 12A. The front end surface 12B of the first die 12 faces the step surface 11B of the punch 11. The front end surface 12B has a shape up to the outer edge of the stepped portion of the door inner panel. That is, the mold bottom surface 12A of the first die 12 and the tip surface 11A of the punch 11 form the top plate portion 2 of the door inner panel 1 shown in FIG. The tip surface 12B of the first die 12 and the step surface 11B of the punch 11 form the step portion 5 of the door inner panel 1 shown in FIG. The first die 12 is attached to the second die 13 via the elastic member 15. The elastic member 15 is, for example, a spring or a hydraulic cylinder.

  The second die 13 includes a reference surface 13A. The reference surface 13A is opposed to the tip surface 14A of the blank holder 14. The second die 13 can be moved up and down by a driving device (not shown). When the second die 13 is lowered, the first die 12 is pushed into the punch 11. Thereby, a door inner panel is shape | molded. That is, the reference surface 13A of the second die 13 and the tip surface 14A of the blank holder 14 form the flange portion 6 of the door inner panel 1 shown in FIG.

  The press apparatus 10 of the present embodiment shows a case where the punch 11 and the blank holder 14 are provided at the lower part of the apparatus, and the first die 12 and the second die 13 are provided at the upper part of the apparatus. However, these arrangements are not limited to the case shown in FIG. That is, in the press device 10, the arrangement of the punch 11 and the blank holder 14 and the first die 12 and the second die 13 may be reversed upside down. In short, the punch 11 and the blank holder 14 may be configured to move relative to the first die 12 and the second die 13.

  4A to 4C are cross-sectional views schematically showing the pressing process of the first embodiment. FIG. 4A shows a stage in which the intermediate molded product is placed in the press device. FIG. 4B shows a stage in which the intermediate molded product is sandwiched between the first die and the punch. FIG. 4C shows the stage where the lowering of the second die is completed (bottom dead center).

  With reference to FIG. 4A, the intermediate molded product 1 </ b> A is disposed in the press device 10. After the intermediate molded product 1A is arranged, the first die 12 and the second die 13 are lowered.

  Referring to FIG. 4B, the top plate portion 2 of the intermediate molded product 1A is sandwiched between the mold bottom surface 12A of the first die 12 and the tip surface 11A of the punch 11. Further, the flange portion 6A of the intermediate molded product 1A is sandwiched between the tip surface 12B of the first die 12 and the step surface 11B of the punch 11. Of the region of the flange portion 6A of the intermediate molded product 1A, the region sandwiched between the tip surface 12B of the first die 12 and the step surface 11B of the punch 11 is the step portion 5 of the door inner panel 1 (see FIG. 4C). .

  After sandwiching the intermediate molded product 1A between the first die 12 and the punch 11, the second die 13 is further lowered. The second die 13 is lowered, and the flange portion 6A of the intermediate molded product 1A is sandwiched between the reference surface 13A of the second die 13 and the tip surface 14A of the blank holder 14. Of the flange portion 6A of the intermediate molded product 1A, the region sandwiched between the reference surface 13A of the second die 13 and the tip surface 14A of the blank holder 14 is the vertical wall portion 4B and the flange portion 6 of the door inner panel 1 (FIG. 4C). Reference).

  Referring to FIG. 4C, the second die 13 is lowered to the bottom dead center, and the step portion 5 of the door inner panel 1 is formed. When forming the stepped portion 5, the top plate portion 2 of the intermediate molded product 1 </ b> A is restrained by the first die 12 and the punch 11. This is because the first die 12 is attached to the second die 13 via an elastic member. Further, the flange portion 6 </ b> A of the intermediate molded product 1 </ b> A is also restrained by the second die 13 and the blank holder 14. Thereby, the wrinkles which generate | occur | produce in the level | step-difference part 5 vicinity of a door inner panel can be suppressed. Hereinafter, this point will be described in detail.

[Suppression of cracks and wrinkles]
FIG. 5 is a cross-sectional view showing a state during pressing by a conventional pressing apparatus. In FIG. 5, the vicinity of the step surface of the die of the conventional press apparatus is shown enlarged. Referring to FIG. 5, in press apparatus 200, tip surfaces 210 </ b> A and 210 </ b> B of punch 210 are formed integrally with punch 210. Therefore, the front end surfaces 210A and 210B of the punch 210 reach the mold bottom surface 220A and the step surface 220B of the die 220 at the same time. The tip surface 210A has a longer distance to push the blank material S than the tip surface 210B. Therefore, as shown in FIG. 5, when the punch 210 is pushed into the die 220, the tip surface 210 </ b> A first pushes the blank material S. At this time, a part S 1 of the blank S is not constrained by the tip surface 210 B of the punch 210 and the step surface 220 B of the die 220.

  As shown in FIG. 5, while the tip surface 210 </ b> A of the punch 210 is processing the blank material S, the blank material S is drawn to the die bottom surface 220 </ b> A side of the die 220. Therefore, the material of the blank material S tends to flow into the region S1 from the region sandwiched between the blank holder 230 and the die 220. If the region S1 is pressed with the material flowing into the region S1, wrinkles are likely to occur in the region S1. This is because there is an extra material flowing into the region S1. Further, during the press working, the unconstrained region S1 receives a force (tension) in the pulling direction. If the region S1 is pressed in a state where the region S1 is under tension, a crack is likely to occur in the region S1. In particular, when the blank material S is thin, cracks are likely to occur.

  On the other hand, the door inner panel manufacturing method of the present embodiment uses a die that is divided into two in the press working step that separates the press working step into two and molds the door inner panel. Therefore, the step portion 5 is molded while restraining the flange portion 6A (corresponding to S1 in FIG. 5) of the intermediate molded product 1A by the first die 12 and the punch 11. Therefore, it is difficult for the material to flow into the stepped portion 5 (corresponding to S1 in FIG. 5) during press working, and tension is not easily generated in the stepped portion 5. Therefore, even if the shape is difficult to form, cracks, wrinkles and the like of the door inner panel can be suppressed.

  Here, in 1st Embodiment, the case where the 2nd die | dye 13 is lowered | hung and the level | step-difference part 5 is shape | molded is shown. Instead of lowering the second die 13, the punch 11 may be raised. In short, the second die 13 and the blank holder 14 may be moved relative to the first die 12 and the punch 11.

  The top plate portion of the door inner panel manufactured in the first embodiment may have a concave portion or a convex portion. The concave portion or the convex portion reinforces the door inner panel. The concave portion or the convex portion may be formed by an intermediate press working step or may be formed by a press working step. From the viewpoint of strength, the depth of the concave portion or the convex portion is preferably deep. However, if the depth of the concave portion or the convex portion is too deep, cracks may occur around the concave portion or the convex portion. In the following second embodiment, a method for forming such a deep concave portion or convex portion will be described.

[Second Embodiment]
[Molding]
FIG. 6 is a view schematically showing a door inner panel formed by the manufacturing method of the second embodiment. In the second embodiment, the door inner panel 20 in which the recess 3 is added to the top plate portion 2 of the door inner panel 1 of the first embodiment is formed. As described above, if the depth of the recess is deep, cracks are likely to occur around the recess. For this reason, such deep recesses are usually formed stepwise in multiple steps. The concave portion of the second embodiment is intended for such a deep concave portion.

  The recessed part 3 is provided along the upper edge part (belt line part) including the edge | side BL on the vehicle upper side of the top-plate part 2, for example. In this case, the recessed part 3 plays the role of the beltline reinforcement which reinforces a beltline part. Moreover, the recessed part 3 may be provided in the center part of the top-plate part 2, for example. In this case, the concave portion 3 serves as a door impact beam that reinforces the top plate portion 2.

  As described above, in the conventional manufacturing method, wrinkles may occur in the stepped portion after press working. In order to suppress this wrinkle, the door inner panel was formed of a steel plate having high workability (low strength). However, the door inner panel is required to have high collision characteristics. Therefore, a reinforcing member such as a door impact beam has been attached to the door inner panel made of a highly workable steel plate. The attachment of the reinforcing member increases man-hours and material costs.

  Therefore, by forming a high-strength blank material on the door inner panel with the manufacturing method of the present embodiment, it is possible to improve the collision characteristics of the door inner panel while suppressing cracks, wrinkles and the like. Furthermore, a reinforcement member can be integrated with a door inner panel by providing a recessed part or a convex part in a top-plate part with the manufacturing method of 2nd Embodiment.

  On the other hand, in order to obtain higher collision characteristics, it is necessary to deepen the concave portion or convex portion of the top plate portion. However, if a deep recess or protrusion is formed in one step, cracks may occur around the recess or protrusion. In order to solve this inconvenience, it is necessary to form the concave portion or the convex portion in a plurality of steps (for example, two steps). However, when the concave or convex shape of the top plate is divided into two steps and molded, excessive wrinkles may occur around the concave or convex portion in the second step.

  The manufacturing method of 2nd Embodiment can suppress generation | occurrence | production of a wrinkle even if it shape | molds a recessed part in a top-plate part divided into several processes. Therefore, the top plate portion can be reinforced without attaching a reinforcing member such as a door impact beam.

[Production method]
7A to 7C are diagrams illustrating a molding process of the door inner panel molded in the second embodiment. FIG. 7A shows the situation after the intermediate press working step. FIG. 7B shows the situation during the press working process. FIG. 7C shows the situation after the pressing process.

The manufacturing method of the second embodiment differs from the manufacturing method of the first embodiment in the following points.
In the intermediate press working step, the raised portion is formed at a position corresponding to the concave portion of the panel-shaped molded product (door inner panel) in the region of the top plate portion of the intermediate molded product.
-In a press work process, the area | region of the protruding part of an intermediate molded product is pressed into the recessed part of a panel-shaped molded product (door inner panel).
Hereinafter, each process is demonstrated with reference to FIG. 7A-FIG. 7C.

[Intermediate press working process]
In the intermediate press process, as in the first embodiment, the blank material is pressed in the cold state to obtain an intermediate molded product. In the second embodiment, a raised portion is formed on the top plate portion of the intermediate molded product.

  As shown in FIG. 7A, the top plate portion 2 of the intermediate molded product 20A has a raised portion 3A. The region of the raised portion 3A is formed in the concave portion 3 of the door inner panel 20 in a later press working process (see FIG. 7C). Therefore, the raised portion 3A is formed at a position where the recessed portion 3 of the door inner panel 20 is formed.

  It is preferable that the raised portion 3 </ b> A is gently formed so as to be wider than the width of the recessed portion 3 of the door inner panel 20. However, it is preferable that the cross-sectional circumference of the raised portion 3 </ b> A is 0.8 to 1.2 times the cross-sectional circumference of the recess 3. This is to prevent the generation of cracks, wrinkles, etc. around the raised portion 3A in the intermediate press working step. As will be described later, the reason why the raised portion 3A is provided in the intermediate molded product 20A is to eliminate a gap between the top plate portion 2 of the intermediate molded product 20A and the tip surface 11A of the punch 11 in a subsequent press working step. .

[Pressing process]
8A to 8C are cross-sectional views schematically showing the press working process of the second embodiment. FIG. 8A shows a stage in which the intermediate molded product is placed in the press device. FIG. 8B shows a stage in which the intermediate molded product is sandwiched between the first die and the punch. FIG. 8C shows the stage where the lowering of the second die is completed (bottom dead center). In addition, in FIG. 8A-FIG. 8C, the principal part of a press apparatus is expanded and shown.

With reference to FIG. 8A, the press apparatus 50 differs in the following points compared with the press apparatus 10 of 1st Embodiment.
The first die 32 has an opening 39; The opening 39 is provided at a position corresponding to the raised portion 3A of the intermediate molded product 20A.
The second die 33 has a protrusion 38. The protrusion 38 is provided at a position corresponding to the opening 39 (the raised portion 3A of the intermediate molded product 20A) of the first die 32. During the press working, the protrusion 38 of the second die 33 penetrates the opening 39 of the first die 32 from above.
Other configurations are the same as those of the press device 10 of the first embodiment.

  The intermediate molded product 20 </ b> A is disposed in the press device 50. After the intermediate molded product 20A is arranged, the first die 32 and the second die 33 are lowered.

  Referring to FIG. 8B, first, the top plate portion 2 of the intermediate molded product 20 </ b> A is sandwiched between the first die 32 and the punch 31. When the second die 33 is further lowered, the protrusion 38 starts to mold the region of the raised portion 3A of the intermediate molded product 20A into the recess. While the projection 38 forms the concave portion, the top plate portion 2 is sandwiched between the first die 32 and the punch 31. This is because the first die 32 is attached to the second die via the elastic member 15.

  Referring to FIG. 8C, after sandwiching the flange portion 6 </ b> A of the intermediate molded product 20 </ b> A between the second die 33 and the blank holder 14, the second die 33 is further lowered to form the stepped portion 5. At this time, the flange portion 6A is restrained by the second die 33 and the blank holder 14 as in the first embodiment. Accordingly, cracks, wrinkles and the like are unlikely to occur in the stepped portion 5. Further, the top plate portion 2 is restrained by the first die 32 and the punch 31 while the projection 38 forms the region of the raised portion 3 </ b> A into the concave portion 3. Thereby, the wrinkles which arise in the circumference | surroundings of the shape | molded recessed part 3 can be suppressed. Hereinafter, this point will be described in detail.

[Suppression of wrinkles around recesses]
Conventionally, when forming recesses in the top plate part of the door inner panel made of steel plate with low workability, if the depth of the recesses is deep, the recesses are gradually formed in multiple steps to suppress cracking. It was. However, when an intermediate molded product having a recess is pressed, wrinkles may occur around the recess.

  FIG. 9 is a cross-sectional view showing a state during pressing by a conventional pressing apparatus. When the intermediate molded product 200 in which the recess 300 is formed is disposed in the press device, the bottom surface 300 </ b> A of the recess 300 is in contact with the tip surface 310 </ b> A of the punch 310. Therefore, there is a gap SP between the top plate portion 220 and the tip surface 310 </ b> A of the punch 310. Due to the gap SP, the top plate portion 220 is not in close contact with the front end surface 310A of the punch 310, and thus wrinkles are likely to occur around the recess 300 after press working.

  On the other hand, in the manufacturing method of the second embodiment, the intermediate molded product 20A having the raised portions 3A is formed before the press working step. When the intermediate molded product 20A having the raised portions 3A is arranged in the press device, the top plate portion 2 and the tip surface 31A of the punch 31 are in contact with each other as shown in FIG. 8A. That is, there is no gap between the top plate portion 2 and the tip surface 31 </ b> A of the punch 31. Thereby, it is hard to produce a wrinkle around the recessed part 3 after press work.

[Third Embodiment]
[Molding]
In 3rd Embodiment, the door inner panel by which the convex part was added to the top-plate part 2 of the door inner panel 1 of 1st Embodiment is shape | molded. The convex part of 3rd Embodiment targets the deep convex part similar to the recessed part of 2nd Embodiment. In short, the door inner panel of the third embodiment has a shape in which the concave portion 3 of the door inner panel 20 of the second embodiment is replaced with a convex portion. The convex part of the door inner panel of 3rd Embodiment plays the role similar to the recessed part 3 of 2nd Embodiment. Moreover, when shape | molding the convex part of the door inner panel of 3rd Embodiment, it is easy to generate | occur | produce a wrinkle for the same reason as the recessed part 3 of 2nd Embodiment. Hereinafter, the manufacturing method of the door inner panel which has a convex part is demonstrated.

[Production method]
The manufacturing method of the third embodiment is different from the manufacturing method of the first embodiment in the following points.
In the intermediate press working step, the depressed portion is formed at a position corresponding to the convex portion of the panel-shaped molded product (door inner panel) in the region of the top plate portion of the intermediate molded product.
-In the pressing process, the region of the depressed portion of the intermediate molded product is pressed into the convex portion of the panel-shaped molded product (door inner panel).

  10A to 10C are cross-sectional views schematically showing the press working process of the third embodiment. FIG. 10A shows a stage in which the intermediate molded product is placed in the press device. FIG. 10B shows a stage in which the intermediate molded product is sandwiched between the first die and the punch. FIG. 10C shows the stage where the lowering of the second die is completed (bottom dead center). Hereafter, each process is demonstrated with reference to FIG. 10A-FIG. 10C.

[Intermediate press working process]
In the intermediate press process, as in the first embodiment, the blank material is pressed in the cold state to obtain an intermediate molded product. In the third embodiment, a depressed portion is formed on the top plate portion of the intermediate molded product.

  As shown in FIG. 10A, the top plate portion 2 of the intermediate molded product 30A has a depressed portion 16A. The region of the depressed portion 16A is formed on the convex portion of the door inner panel in a subsequent press working process. Therefore, the depressed portion 16A is formed at a position where the convex portion of the door inner panel is formed.

[Pressing process]
Referring to FIG. 10A, the press device 60 is different from the press device 10 of the first embodiment in the following points.
The punch 61 has an opening 69 disposed at a position corresponding to the depressed portion 16 </ b> A of the intermediate molded product 30 </ b> A, and a protrusion 68 disposed at a position corresponding to the opening 69. At the time of press working, the protrusion 68 of the punch 61 penetrates the opening 69 of the punch 61 from below.
Other configurations are the same as those of the press device 10 of the first embodiment.

  The intermediate molded product 30 </ b> A is disposed in the press device 60. After the intermediate molded product 30A is arranged, the first die 62 and the second die 63 descend.

  Referring to FIG. 10B, first, the top plate portion 2 of the intermediate molded product 30 </ b> A is sandwiched between the first die 62 and the punch 61. When the second die 63 is further lowered, the protrusion 68 starts to mold the region of the depressed portion 16A of the intermediate molded product 30A into a convex portion. While the projection 68 forms the convex portion, the top plate portion 2 is sandwiched between the first die 62 and the punch 61. This is because the first die 62 is attached to the second die 63 via the elastic member 15.

  In the third embodiment, the punch 61 is attached to the base of the press device 60 via the elastic member 25. The protrusion 68 is directly attached to the base of the press device 60. That is, the protrusion 68 is not attached to the press device 60 via the elastic member. Therefore, when the first die 62 and the second die 63 are lowered, the protrusion 68 penetrates the opening 69 of the punch 61.

  With reference to FIG. 10C, after sandwiching the flange portion 6A of the intermediate molded product 30A between the second die 63 and the blank holder 14, the second die 63 is further lowered to form the step portion 5. At this time, the flange portion 6A is restrained by the second die 63 and the blank holder 14 as in the first embodiment. Accordingly, cracks, wrinkles and the like are unlikely to occur in the stepped portion 5. Further, the top plate portion 2 is restrained by the first die 62 and the punch 61 while the projection 68 is forming the region of the depressed portion 16 </ b> A into the convex portion 16. Thereby, the wrinkle which arises around the convex part 16 shape | molded can be suppressed.

  In the above-described embodiment, the steel plate may be a tailored blank. Tailored blanks are roughly classified into tailored welding blanks (hereinafter also referred to as “TWB”) and tailored rolled blanks (hereinafter also referred to as “TRB”). TWB is obtained by integrating a plurality of types of steel plates having different thicknesses, tensile strengths, and the like by welding (for example, butt welding). On the other hand, TRB has a plate thickness changed by changing the interval between rolling rolls when manufacturing a steel plate. When a tailored blank is used, the strength can be strengthened by limiting to a necessary portion, and the plate thickness can also be reduced. Moreover, the panel-shaped molded article using the tailored blank can also be applied to the door inner panel for automobiles. Thereby, a collision characteristic can be improved and weight reduction can be expected.

  In the above description, the case where the material of the door inner panel is a steel plate has been described. However, the material of the door inner panel is not limited to a steel plate, and may be a metal plate. Examples of the metal plate include an aluminum plate, an aluminum alloy plate, a multilayer steel plate, a titanium plate, and a magnesium plate. In the above description, the case where the panel-shaped molded product is a door inner panel has been described. However, the panel-shaped molded product is not limited to the door inner panel. Panel-shaped molded products can be applied to products that require excellent impact characteristics. Such products are, for example, vehicles, construction machines, aircraft, etc., in addition to automobiles.

  The embodiment of the present invention has been described above. However, the above-described embodiment is merely an example for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately changing the above-described embodiment without departing from the spirit thereof.

1, 20 Panel-shaped molded product (door inner panel)
1A, 20A, 30A Intermediate molded product 2 Top plate part 3 Recessed part 3A Raised part 4, 4A, 4B Vertical wall part 5 Step part 10, 50, 60, 200 Press device 11, 31, 61, 210 Punch 12, 32, 62 First die 13, 33, 63 Second die 38, 68 Protrusion 39, 69 Opening portion 14, 230 Blank holder 16 Convex portion 16A Depressed portion S Blank material

Claims (5)

A method for producing a panel-shaped molded article,
The panel-shaped molded article includes a polygonal top plate portion, a vertical wall portion extending from each of at least two sides of the top plate portion, and a vertical wall portion adjacent to the vertical wall portion. A step portion provided on each vertical wall portion of at least one set of the set,
The manufacturing method includes:
A preparation step of preparing a blank made of a metal plate;
An intermediate press process for obtaining an intermediate molded product obtained by cold-pressing the blank material, forming the top plate portion, and forming the vertical wall portion to the height of the stepped portion,
A process of cold-pressing the intermediate molded product to obtain the panel-shaped molded product,
In the pressing process,
A first die in which a shape up to an outer edge of the top plate part and the step part is formed;
A second die disposed outside the first die;
A punch facing the first die and having the top plate and the stepped portion formed therein,
A blank holder facing the second die;
Using a press device equipped with
In a state where the intermediate molded product is sandwiched between the first die and the punch, the second die and the blank holder are moved relative to the first die and the punch to form the panel-shaped molded product. A method for manufacturing a panel-shaped molded product. It is a manufacturing method of the panel-shaped molded product according to claim 1,
The top plate portion of the panel-shaped molded product has a recess,
In the intermediate press working process,
A raised portion is formed at a position corresponding to the concave portion of the panel-shaped molded product in the region of the top plate portion of the intermediate molded product,
In the pressing process,
The first die has an opening at a position corresponding to the raised portion of the intermediate molded product,
The second die has a protrusion at a position corresponding to the opening of the first die,
A method for manufacturing a panel-shaped molded product, wherein the protrusion is used to press the region of the raised portion of the intermediate molded product into the concave portion of the panel-shaped molded product. It is a manufacturing method of the panel-shaped molded product according to claim 1,
The top plate portion of the panel-shaped molded product has a convex portion,
In the intermediate press working process,
Of the region of the top plate portion of the intermediate molded product, forming a depressed portion at a position corresponding to the convex portion of the panel-shaped molded product,
In the pressing process,
The punch has an opening disposed at a position corresponding to the depressed portion of the intermediate molded product, and a protrusion disposed at a position corresponding to the opening.
A method for manufacturing a panel-shaped molded product, wherein the protrusions press the region of the depressed portion of the intermediate molded product onto the convex portion of the panel-shaped molded product. It is a manufacturing method of the panel-shaped molded article of any one of Claims 1-3,
The panel-shaped molded product manufacturing method according to claim 1, wherein a tensile strength of the panel-shaped molded product after the pressing step is 390 MPa or more and 980 MPa or less. It is a manufacturing method of the panel-shaped molded product according to any one of claims 1 to 4,
The said metal plate is a tailored blank, The manufacturing method of a panel-shaped molded product.

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