JP7060233B2 - Molding method for press-molded products - Google Patents

Description

The present invention relates to a method for forming a press-molded product from which a press-molded product is obtained from a metal plate.

In the automobile industry in recent years, a lightweight and highly safe vehicle body structure is required, and in response to this demand, a press-molded product having a cross-section hat shape made of high-strength steel plate may be applied to the frame portion of the vehicle body structure. .. However, in the case of obtaining a press-molded product having a cross-section hat shape from a high-strength steel plate, when the molding die is opened after the molding is completed, a phenomenon called springback occurs in which both vertical wall portions facing each other expand in a V shape. It is known that it is easy and the dimensional accuracy after press molding deteriorates with respect to the target shape.

In order to deal with this, the amount of expansion of each vertical wall portion after the completion of molding is estimated in advance, and the region that becomes the upper surface portion of the metal plate during molding is bent and deformed by a large amount. By setting it, it is generally performed to bring the press-molded product after molding closer to the target shape.

However, in the above case, it is necessary to bend and deform each vertical wall region with respect to the upper surface region so that the angle between the upper surface region and each vertical wall region becomes an acute angle. Therefore, it is not possible to handle molding with a molding die that only closes the mold in the same direction as the ascending / descending direction of the press machine. Therefore, it is necessary to equip the molding die with a cam die that operates in a direction intersecting the elevating direction of the press machine, which causes a problem that the die cost increases. Further, when manufacturing a molding die as described above, there is also a problem that the lead time for development becomes long because it is not possible to arrange castings until the estimated amount of each vertical wall portion can be predicted.

In order to avoid these problems, for example, the region that becomes the upper surface portion of the high-strength steel plate, instead of both vertical wall portions, is elastic so as to be displaced by a predetermined amount from the position of the target shape at the time of molding. The area to be the vertical wall part of the high-strength steel plate is targeted by utilizing the fact that the elastically deformed portion that has been deformed and opened with the opening of the molding die after the completion of molding is deformed to the position of the target shape. It is conceivable to use a method such as Patent Document 1 that brings the position closer to the above position.

Patent No. 5262303

By the way, the press-molded product having a hat-shaped cross section has a pair of continuous flange portions on each vertical wall portion, and the bending direction of each vertical wall portion and each vertical wall with respect to the region that becomes the upper surface portion during press molding. The bending direction of each flange portion with respect to the portion is not the same direction.

On the other hand, in Patent Document 1, press forming is performed so that the press-formed product has a closed cross section, and the bending directions of the portions where bending deformation is applied to the metal plate are all in the same direction, and the metal plate is subjected to bending deformation. When the directions in which bending deformation is applied are not all in the same direction, no consideration is given to bringing the press-formed product after molding closer to the target shape without using a cam mold.

The present invention has been made in view of these points, and an object thereof is to be able to mold with high accuracy, reduce mold cost, and shorten the lead time of development. It is an object of the present invention to provide a method for forming a press-molded product having a hat-shaped cross section.

In order to achieve the above object, the present invention is characterized in that two molding dies are prepared, and the parts where plastic deformation and elastic deformation are applied to the metal plate and the order thereof are devised. ..

Specifically, a pair of vertical walls extending from an upper surface portion extending in a substantially horizontal strip shape and both edge portions extending along the longitudinal direction of the upper surface portion so as to face each other and intersecting the upper surface portion. A method for forming a press-molded product from a metal plate, which has a cross-sectional hat shape having a portion and a pair of flange portions extending in a direction away from each other from the extending end of each vertical wall portion, is as follows. I took such measures.

That is, in the first invention, the region that becomes each vertical wall portion with respect to the region that becomes the upper surface portion by carrying the metal plate into the primary molding mold and closing the mold of the primary molding mold. The metal plate is plastically deformed so that the angle becomes blunt, and the angle of the region of each flange portion with respect to the region of each vertical wall portion is the same as the angle of the corresponding portion of the final molded body. After plastically deforming the metal plate to obtain a primary molded body , a secondary having a holder mold for secondary molding in which a first upper molded surface corresponding to a region to be an upper surface portion in the primary molded body is formed on the lower surface. The upper mold for molding and the lower mold for secondary molding formed at a position where the first lower molding surface having a curved shape recessed downward faces the first upper molding surface, and the first upper molding On the surface, a first pressing surface and a second pressing surface are formed on both sides, and a third pressing surface having a curved shape with a central portion protruding downward between the first pressing surface and the second pressing surface is formed. The formed secondary molding mold is prepared, the primary molded body is carried into the secondary molding mold, the secondary molding mold is closed, and the above-mentioned region to be the upper surface portion is described. The primary molded body is plastically deformed so that the angle of the region to be each vertical wall portion is the same as the angle of the corresponding portion of the final molded body, and the region to be both vertical wall portions of the metal plate is plastically deformed. After obtaining a secondary molded body having a curved deformed portion elastically deformed so that the region to be the upper surface portion is curved from the position of the target shape of the upper surface portion on the deformed side, the secondary molding is performed. The region that becomes the vertical wall part does not expand outward in conjunction with the deformation operation of the curved deformation part that deforms to the target shape by opening the elastic deformation in the curved deformation part due to the mold opening of the mold. The region becomes a target shape of the final molded body to obtain the final molded body, and the curved deformed portion is formed by the first pressing surface and one of the curved deformed portions. In the first ridge line portion connected to the plastically deformed portion between the vertical wall portion and the plastically deformed portion between the first ridge line portion and the other vertical wall portion in the curved deformed portion formed by the second pressing surface. It is composed of a second ridge line portion to be connected and a third ridge line portion formed by the third pressing surface and connecting between the first ridge line portion and the second ridge line portion, and has a radius of curvature of the third ridge line portion. The curvature deformation is set to be larger than each radius of curvature of the first ridge line portion and the second ridge line portion, and the curvature radiuss of the first ridge line portion, the second ridge line portion, and the third ridge line portion are changed, respectively. It is characterized in that it is configured to adjust the amount of elastic deformation of the portion .

In the first invention, since the molding is controlled so that each vertical wall portion has a target shape by utilizing the elastic deformation of the curved deformed portion that becomes the upper surface portion of the metal plate, the region becomes the upper surface portion of the metal plate. It is not necessary to bend and deform each vertical wall region with respect to the upper surface region of the metal plate so that the angle between the vertical wall region and the vertical wall region is sharp. Therefore, it is not necessary to equip the mold used for molding with a cam mold that operates in a direction intersecting the elevating direction of the press machine, so that the mold cost can be suppressed. In addition, since it is not necessary to predict the estimated amount at the time of molding of each vertical wall portion of the metal plate, it is possible to accelerate the arrangement of castings for manufacturing the mold and shorten the development lead time. Can be done.

Further , it becomes possible to control the molding position without plastically deforming the region to be the vertical wall portion of the metal plate by adding a prospective amount, and for example, when molding a press-molded product having an asymmetric cross section. By setting the radius of curvature of the first and second ridges to different values, each vertical wall can be accurately deformed to the target molding position, and it is a press-molded product with a complicated cross-sectional hat shape. However, it is possible to accurately approach the target shape after molding.

It is a block diagram of the production line to which the molding method which concerns on embodiment of this invention is applied. It is a schematic cross-sectional view which shows the state immediately after the high-strength steel plate was carried into the 1st forming die of a primary forming process. After FIG. 2, it is a figure which shows the state in the process of molding a primary molded body by starting to close a 1st molding die. After FIG. 3, it is a figure which shows the state immediately after the first molding die was closed and the primary molded body was molded. After FIG. 4, it is a figure which shows the state just before the first molding die is opened and the primary molded body is carried out. After FIG. 5, is a schematic cross-sectional view showing a state immediately after the primary molded body is carried into the second molding die in the secondary molding step. FIG. 6 is an enlarged view of part VII of FIG. After FIG. 6, it is a figure which shows the state in the process of molding a secondary molded body by starting to close a 2nd molding die. After FIG. 8, it is a figure which shows the state immediately after the second molding die was closed and the secondary molded body was molded. FIG. 9 is an enlarged view of part X in FIG. After FIG. 9, it is a figure which shows the state which the 2nd molding die was opened and the final molded body was obtained from the secondary molded body. FIG. 7 is a view corresponding to FIG. 7 showing a modified example of the second molding die used in the embodiment of the present invention. The results of evaluating the maximum amount of deviation between the position of the vertical wall portion and the position of the target shape in the press-molded product molded by the molding method of the present invention while changing the shape, material strength and plate thickness of the curved deformed portion are shown. It is a table.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is essentially merely an example.

1 to 11 show a production line 1 according to an embodiment of the present invention. The production line 1 is capable of obtaining a press-formed product 10 from the high-strength steel plate S1 (metal plate), and stores the high-strength steel plate S1 before forming in order from the upstream side of the production line 1. The carry-in step 2, the primary molding step 3 in which the high-strength steel plate S1 carried in from the carry-in step 2 is press-molded to obtain the primary molded body P1, and the primary molded body P1 obtained in the primary molding step 3 are press-molded. The secondary molding step 4 for obtaining the secondary molded body P2 (final molded body P3) and the carrying-out step 5 for storing the final molded body P3 taken out from the secondary molding step 4 are arranged in this order.

The press-molded product 10 has a cross-sectional hat shape, and as shown in FIG. 11, the upper surface portion 10a extending in a substantially horizontal direction and both edges extending along the longitudinal direction of the upper surface portion 10a face each other. Further, a pair of vertical wall portions 10b extending so as to intersect the upper surface portion 10a and a pair of flange portions 10c extending in a direction away from each other from the extending end of each vertical wall portion 10b are provided, and the upper surface portion 10a and the vertical wall are provided. The angle between the portion 10b and the vertical wall portion 10b is about 90 degrees, and the angle between the vertical wall portion 10b and the flange portion 10c is about 90 degrees.

In the carry-in step 2, a plurality of steel plates S1 cut into an appropriate shape are placed in a laminated state, and an industrial robot (not shown) carries the steel plates S1 one by one into the primary forming step 3. There is.

As shown in FIGS. 2 to 5, the primary forming step 3 includes a primary forming die 3a that plastically deforms the steel sheet S1 by applying pressure from above and below.

The primary forming die 3a is composed of a primary forming upper die 6 and a primary forming lower die 7 facing vertically, and a primary forming upper die 6 is used with respect to the primary forming lower die 7 by a press machine (not shown). It is designed to move up and down.

The primary molding upper mold 6 has a primary molding upper mold main body 61 in which a first accommodating recess 61a that opens downward is formed in the central portion, and a primary forming upper mold 6 that is slidably accommodated in the first accommodating recess 61a. It is provided with a holder type 62.

The primary forming holder mold 62 is urged downward by the primary forming coil spring 63, and a part of the region protrudes downward from the opening portion of the first accommodating recess 61a in the state before the start of forming.

On the lower surface of the holder mold 62 for primary forming, an upper flat surface 6a for forming a region to be the upper surface portion 10a of the high-strength steel plate S1 is formed.

On the other hand, a pair of first upper inclined surfaces 6b for forming a region to be a vertical wall portion 10b in the high-strength steel plate S1 are formed around the opening of the first accommodating recess 61a in the primary forming upper die main body 61. 1 The upper inclined surface 6b is inclined and extended so as to be gradually separated from each other as it goes downward.

That is, the angle formed by the upper flat surface 6a and the first upper inclined surface 6b is an obtuse angle when the upper die 6 for primary molding reaches the bottom dead center.

On the outer side of each first upper inclined surface 6b, a pair of second upper inclined surfaces 6c forming a region to be a flange portion 10c in the high-strength steel plate S1 are continuous with the extending end of each first upper inclined surface 6b. The second upper inclined surface 6c is inclined and extends so as to be separated from each other as it goes upward.

The angle formed by the first upper inclined surface 6b and the second upper inclined surface 6c is about 90 degrees, and the continuous first upper inclined surface 6b and the second upper inclined surface 6c form a convex shape protruding downward. Nothing.

On the other hand, in the center of the upper surface of the lower mold 7 for primary forming, a lower flat surface 7a for forming a region to be the upper surface portion 10a of the high-strength steel plate S1 is formed, and the lower flat surface 7a is formed on the upper flat surface 6a. It is in the opposite position.

On both sides of the lower flat surface 7a, a pair of first lower inclined surfaces 7b corresponding to the region to be the vertical wall portion 10b of the high-strength steel plate S1 are continuously formed at both ends of the lower flat surface 7a. There is.

The first lower inclined surface 7b is inclined and extended so as to be gradually separated from each other as it goes downward, and is at a position facing the first upper inclined surface 6b.

That is, the angle formed by the lower flat surface 7a and the first lower inclined surface 7b is an obtuse angle, and the lower flat surface 7a and the pair of the first lower inclined surfaces 7b form a convex shape protruding upward. Nothing.

On the outer side of each first lower inclined surface 7b, a pair of second lower inclined surfaces 7c forming a region to be a flange portion 10c in the high-strength steel plate S1 are extended ends of each first lower inclined surface 7b. It is continuously formed in.

The second lower inclined surface 7c is inclined and extends so as to be separated from each other as it goes upward, and is at a position facing the second upper inclined surface 6c.

The angle formed by the first lower inclined surface 7b and the second lower inclined surface 7c is about 90 degrees, and the continuous first lower inclined surface 7b and the second lower inclined surface 7c are upward. It has a concave shape to open.

Then, when the high tension steel plate S1 is carried in between the primary forming upper die 6 and the primary forming lower die 7 of the primary forming die 3a and the primary forming die 3a is closed, FIGS. 3 and 4 show. As shown in the above, the high tension steel plate S1 is plastically deformed so that the angle of the region to be the vertical wall portion 10b is blunt with respect to the region to be the upper surface portion 10a due to the mold closing operation of the primary forming die 3a. At the same time, the high tension steel plate S1 is plastically deformed so that the angle of the region of each flange portion 10c with respect to the region of each vertical wall portion 10b is about 90 degrees, so that the primary molded body P1 can be obtained.

As shown in FIGS. 6 to 11, the secondary molding step 4 includes a secondary molding die 4a that plastically deforms the primary molded body P1 by applying pressure from above and below.

The secondary forming die 4a includes an upper die 8 for secondary forming and a lower die 9 for secondary forming that face each other vertically, and an upper die 8 for secondary forming is used for secondary forming by a press machine (not shown). It is designed to move up and down with respect to the lower mold 9.

The secondary molding upper mold 8 has a secondary molding upper mold main body 81 in which a second accommodating recess 81a that opens downward is formed in the central portion, and a second accommodating recess 81a that is slidably accommodated in the second accommodating recess 81a. It is provided with a holder mold 82 for next molding.

The secondary forming holder mold 82 is urged downward by the secondary forming coil spring 83, and a part of the region protrudes downward from the opening portion of the second accommodating recess 81a in the state before the start of forming.

The lower surface of the holder mold 82 for secondary molding has a shape extending in the horizontal direction, and a first upper molding surface 8a corresponding to a region to be the upper surface portion 10a in the primary molding body P1 is formed.

On the other hand, around the opening of the second accommodating recess 81a in the upper mold main body 81 for secondary molding, a pair of upper surfaces extending gradually downward while being separated outward from the opening peripheral edge of the second accommodating recess 81a. A pair of second upper moldings having a shape extending in a substantially vertical direction downward from the extending end of each of the curved molding surfaces 8d and the upper curved molding surface 8d, and corresponding to a region to be a vertical wall portion 10b in the primary molded body P1. The third upper molded surface 8c has a substantially flat shape extending horizontally from the extending end of each of the second upper molded surfaces 8b to the surface 8b, and corresponds to the region of the primary molded body P1 that becomes the flange portion 10c. And have.

As shown in FIG. 7, the first upper forming surface 8a and the first pressing surface 80a continuous with the R stop of one of the upper curved forming surfaces 8d in a state where the upper die 8 for secondary forming reaches the bottom dead center. The second pressing surface 80b continuous with the R stop of the other upper curved forming surface 8d, the first pressing surface 80a, and the second pressing surface 80b in a state where the upper die 8 for secondary forming reaches the bottom dead center. It is composed of a third pressing surface 80c that is continuous between them, and the first pressing surface 80a, the third pressing surface 80c, and the second pressing surface 80b are smoothly continuous.

The first pressing surface 80a, the second pressing surface 80b, and the third pressing surface 80c are gently curved, and assuming that the respective radii of curvature are R1, R2, and R3, the relationship is R3> R1 = R2.

Further, the third pressing surface 80c has a gently curved shape in which the central portion of the third pressing surface 80c projects downward by the amount of protrusion h.

On the other hand, as shown in FIG. 6, the upper surface of the lower mold 9 for secondary molding has a substantially flat shape extending in the horizontal direction, and has a first lower molding surface 9a corresponding to the first upper molding surface 8a. A pair of second lower molding surfaces 9b corresponding to each second upper molding surface 8b and each second lower side having a shape extending downward from both ends of the first lower molding surface 9a in a substantially vertical direction. It has a substantially flat shape extending horizontally from the extending end of the molding surface 9b, and has a third lower molding surface 9c corresponding to each third upper molding surface 8c, and has a first lower molding surface 9a. A pair of lower curved molded surfaces 9d corresponding to each upper curved molded surface 8d are formed between the second lower molded surface 9b.

The first lower molding surface 9a is formed at a position facing the first upper molding surface 8a, and has a curved shape that is gently recessed downward.

Then, when the primary molded body P1 is carried in between the secondary forming upper die 8 and the secondary forming lower die 9 in the secondary forming die 4a and the secondary forming die 4a is closed, FIG. 6 As shown in FIG. 10, the primary molded body P1 is plastically deformed so that the angle of the region to be the vertical wall portion 10b is about 90 degrees with respect to the region to be the upper surface portion 10a, and the primary molded body P1 is formed. A secondary having a curved deformed portion 11 elastically deformed so that the region to be the upper surface portion 10a is more curved than the position of the target shape of the upper surface portion 10a on the side where the region to be the both vertical wall portions 10b is plastically deformed. The molded body P2 can be obtained.

As shown in FIG. 10, the curved deformed portion 11 has a first ridge line portion 11a connected to a bent portion between one upper curved molded surface 8d and one lower curved molded surface 9d in the primary molded body P1. The second ridge line portion 11b, the first ridge line portion 11a, and the second ridge line portion 11b connected to the bent portion between the other upper curved molding surface 8d and the other lower curved molding surface 9d in the primary molded body P1. The first ridge line portion 11a, the second ridge line portion 11b, and the third ridge line portion 11c are smoothly continuous.

The first ridge line portion 11a is a region formed by the first pressing surface 80a, and has a radius of curvature of R1. Further, the second ridge line portion 11b is a region formed by the second pressing surface 80b, and the radius of curvature is R2. Further, the third ridge line portion 11c is a region formed by the third pressing surface 80c, and the radius of curvature is R3.

After closing the secondary molding die 4a to obtain the secondary molded body P2, when the secondary forming die 4a is opened, as shown in FIG. 11, the secondary forming die 4a The elastic deformation in the curved deformation portion 11 is released with the mold opening, and the curved deformation portion 11 is deformed to a target shape. At that time, the region of the secondary molded body P2 is deformed to the position of the target shape in conjunction with the deformation operation of the curved deformation portion 11 so that the region to be the vertical wall portion 10b does not expand outward. The final molded product P3 (press molded product 10) is obtained.

In the carry-out step 5, a plurality of press-molded products 10 molded in the secondary molding step 4 are stored in a stacked state, and an industrial robot (not shown) sequentially carries out each press-molded product 10 to the next step. It has become.

In the embodiment of the present invention, the radius of curvature R1 of the first pressing surface 80a and the radius of curvature R2 of the second pressing surface 80b and the radius of curvature R3 of the third pressing surface 80c are different values. As shown in 12, a mold structure may be used in which the values of the radii of curvature of the first pressing surface 80a, the second pressing surface 80b, and the third pressing surface 80c on the first upper molding surface 8a are the same.

Next, a method of molding the press-molded product 10 on the production line 1 will be described in detail.

FIG. 2 shows a state immediately after the high-strength steel plate S1 is carried in from the carry-in step 2 to the primary forming step 3. From the state of FIG. 2, first, as shown in FIG. 3, a press machine (not shown) is operated to lower the primary molding upper die 6 (arrow X1). Then, the upper flat surface 6a of the primary forming holder mold 62 comes into contact with the upper surface of the high-strength steel plate S1, and the primary forming holder mold 62 resists the urging force of the primary forming coil spring 63, and the primary forming upper mold main body 61. The continuous portion of the first upper inclined surface 6b and the second upper inclined surface 6c comes into contact with the outer portion of the high-strength steel plate S1 and begins to press the contact portion downward (as it begins to slide upward with respect to the above). Hereinafter, the pressing portion is referred to as a pressing portion V1), and the upper surface portion 10a of the high-strength steel plate S1 is formed with a continuous portion (hereinafter referred to as a continuous portion F1) of the lower flat surface 7a and the first lower inclined surface 7b as a fulcrum. The region that becomes the vertical wall portion 10b with respect to the region begins to bend.

When the upper die 6 for primary forming is further lowered from the state of FIG. 3, the high-strength steel plate S1 comes into contact with a portion outside the pressing portion V1 on the second lower inclined surface 7c (hereinafter, the contact portion is referred to as a contact portion F2). ), The outer portion of the high-strength steel plate S1 is pushed by the pressing portion V1 with the continuous portion F1 and the contact portion F2 as fulcrums, and bends in a substantially V shape. Then, when the upper die 6 for primary molding reaches the bottom dead point, as shown in FIG. 4, high tension is obtained so that the angle of the region to be the vertical wall portion 10b is obtuse with respect to the region to be the upper surface portion 10a. Along with the plastic deformation of the steel plate S1, the high-strength steel plate S1 is plastically deformed so that the angle of the region of each flange portion 10c with respect to the region of each vertical wall portion 10b is about 90 degrees to obtain the primary molded body P1. ..

After that, as shown in FIG. 5, the primary molding die 3a is opened and the primary molded body P1 is conveyed to the secondary molding step 4.

FIG. 6 shows a state immediately after the primary molded body P1 is carried from the primary molding step 3 to the secondary molding step 4. From the state shown in FIG. 6, a press machine (not shown) is operated to lower the secondary molding upper die 8 (arrow X2). Then, the first upper forming surface 8a of the secondary forming holder mold 82 comes into contact with the upper surface of the region of the primary forming body P1 to be the upper surface portion 10a, and the secondary forming holder type 82 is attached with the secondary forming coil spring 83. It begins to slide upward with respect to the upper mold body 81 for secondary molding against the force, and as shown in FIG. 8, the primary molded body is formed on the continuous portion of the second upper molding surface 8b and the third upper molding surface 8c. The primary molded body P1 is plastically deformed so that the angle of the region to be the vertical wall portion 10b is about 90 degrees with respect to the region to be the upper surface portion 10a while the region to be the vertical wall portion in P1 is in sliding contact.

Then, when the upper mold 8 for secondary molding is further lowered from the state of FIG. 8 to reach the bottom dead center, as shown in FIG. 9, the first upper molding surface 8a becomes the upper surface portion 10a of the primary molding body P1. A secondary molded body P2 having a curved deformed portion 11 elastically deformed by pressing the region downward is obtained.

After that, as shown in FIG. 11, when the secondary molding die 4a is opened, the elastic deformation in the curved deformation portion 11 is released. Then, the region of the secondary molded body P2 that becomes the vertical wall portion 10b tries to expand outward (in the direction of arrow Y1) by springback, but the curved deformed portion 11 is elastically deformed to the target shape (flat shape). By doing so, a force in the rotational direction (force in the arrow Y2 direction) along the continuous portion is applied to the continuous portion between the region that becomes the upper surface portion 10a and the region that becomes the vertical wall portion 10b in the secondary molded body P2, and is secondary. The region of the molded body P2 that becomes the vertical wall portion 10b does not expand outward, but the region is deformed to a position of the target shape to obtain the final molded body P3 (press molded product 10).

FIG. 13 shows the position of the vertical wall portion 10b in the press-molded product 10 when the press-molded product 10 is molded by the molding method of the present invention while changing the shape of the curved deformed portion 11 in the secondary molded product P2. This is the result of an experiment on how much the position deviates from the target shape position at the maximum. In the experiment, as shown in FIG. 7, the radius of curvature r of the first pressing surface 80a and the second pressing surface 80b of the first upper forming surface 8a in the secondary forming die 4a and the lower side of the third pressing surface 80c. The shape of the curved deformation portion 11 was changed by changing the protrusion amount h of the above.

From this experimental result, the radius of curvature r of the first pressing surface 80a and the second pressing surface 80b and the protrusion amount h of the third pressing surface 80c are set according to the material strength and the plate thickness of the high-strength steel plate S1. It was found that the molding position of each vertical wall portion 10b in the press-molded product 10 can be changed.

That is, the radius of curvature of the third ridge line portion 11c is set to be larger than the radius of curvature of the first ridge line portion 11a and the second ridge line portion 11b, and the first ridge line portion 11a, the second ridge line portion 11b, and the third ridge line portion are set. By changing the radius of curvature in 11c, the amount of elastic deformation of the curved deformation portion 11 can be adjusted to control the position of each vertical wall portion 10b in the press-molded product 10 after molding.

From the above, according to the embodiment of the present invention, the molding is controlled so that each vertical wall portion 10b has a target shape by utilizing the elastic deformation of the curved deformed portion 11 which becomes the upper surface portion 10a of the high-strength steel plate S1. It is necessary to bend and deform the region to be the vertical wall portion 10b with respect to the region to be the upper surface portion 10a in the high-strength steel plate S1 so that the angle between the upper surface portion 10a and each vertical wall portion 10b is an acute angle. It disappears. Therefore, it is not necessary to equip the mold used for molding with a cam mold that operates in a direction intersecting the elevating direction of the press machine, so that the mold cost can be suppressed.

Further, since it is not necessary to predict the estimated amount at the time of forming the region to be each vertical wall portion 10b in the high-strength steel plate S1, it is possible to accelerate the arrangement of castings for manufacturing the mold and to shorten the development lead time. Can be shortened.

Further, it becomes possible to control the forming position of the high-strength steel plate S1 without adding a prospective amount to the region to be the vertical wall portion 10b and plastically deforming the high-strength steel plate S1, and for example, a press-formed product 10 having an asymmetric cross section. By setting the radii of curvature R1 and R2 of the first ridge line portion 11a and the second ridge line portion 11b to different values in the case of molding, each vertical wall portion 10b can be accurately deformed to the target molding position. Even a press-molded product 10 having a complicated cross-sectional hat shape can be accurately approached to a target shape after molding.

In the embodiment of the present invention, the press-molded product 10 is press-molded from the high-strength steel plate S1, but the molding method of the present invention may be applied when the press-molded product 10 is molded from another metal plate. can.

The present invention is suitable for a molding method of a press-molded product for obtaining a press-molded product from a metal plate.

3a Primary molding die 4a Secondary forming die 10 Press-molded product 10a Top surface part 10b Vertical wall part 10c Flange part 11 Curved deformation part 11a First ridge line part 11b Second ridge line part 11c Third ridge line part P1 Primary molded body P2 Secondary molded body P3 Final molded body S1 High tension steel plate (metal plate)

Claims (1)

An upper surface portion extending in a substantially horizontal strip shape, a pair of vertical wall portions extending so as to face each other from both edge portions extending along the longitudinal direction of the upper surface portion and intersecting the upper surface portion, and the said. It is a molding method of a press-molded product for obtaining a press-molded product having a cross-sectional hat shape having a pair of flange portions extending in a direction away from each other from the extending end of each vertical wall portion from a metal plate.
The metal plate is carried into the primary molding die, and the angle of each vertical wall portion is blunt with respect to the region that becomes the upper surface portion due to the mold closing operation of the primary molding die. The metal plate is plastically deformed, and the metal plate is plastically deformed so that the angle of the region to be the flange portion with respect to the region to be the vertical wall portion is the same as the angle of the corresponding portion of the final molded body. After obtaining the primary molded body
The upper mold for secondary molding having a holder mold for secondary molding in which the first upper molding surface corresponding to the region to be the upper surface portion in the primary molded body is formed on the lower surface, and the first mold having a curved shape recessed downward. The lower molding surface is composed of a lower mold for secondary molding formed at a position facing the first upper molding surface, and the first upper molding surface has a first pressing surface and a second pressing surface on both sides. A secondary molding die is prepared in which a third pressing surface having a curved shape in which the central portion protrudes downward is formed between the first pressing surface and the second pressing surface.
The primary molded body is carried into a secondary forming mold, the secondary forming mold is closed, and the angle of the region to be each vertical wall portion with respect to the region to be the upper surface portion is the final molding. The primary molded body is plastically deformed so as to have the same angle as the corresponding portion of the body, and the region to be the upper surface is on the side where the regions to be both vertical walls of the metal plate are plastically deformed. After obtaining a secondary molded body having a curved deformed portion elastically deformed so as to be curved from the position of the target shape of the upper surface portion, in the curved deformed portion accompanying the mold opening of the secondary molding die. The region that becomes the vertical wall portion does not expand outward in conjunction with the deformation operation of the curved deformation portion that deforms to the target shape by releasing the elastic deformation, and the region becomes the target shape of the final molded body . Then, the above-mentioned final molded body is obtained .
The curved deformed portion is formed by the first ridge line portion formed by the first pressing surface and connected to the plastically deformed portion between the curved deformed portion and the region to be one of the vertical wall portions, and the second pressing surface. The second ridge line portion connected to the plastically deformed portion between the curved deformed portion and the region to be the other vertical wall portion, and the first ridge line portion and the second ridge line portion formed by the third pressing surface. It is composed of a third ridge line portion connecting the two, and the radius of curvature of the third ridge line portion is set to be larger than each radius of curvature of the first ridge line portion and the second ridge line portion, and the first ridge line portion is set. , A method for forming a press-molded product, characterized in that the elastic deformation amount of the curved deformation portion is adjusted by changing the radius of curvature in the second ridge line portion and the third ridge line portion, respectively .

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