JP6750596B2 - Mold shape determination method - Google Patents

Description

The present invention determines the shape of a mold for bending a metal base plate into a mountain shape to mold a molding member having a substantially L-shaped cross-section so that the bending angle of the bending becomes a target angle after releasing from the mold. The present invention relates to a mold shape determination method.

In recent years, high-strength steel sheets have been frequently used for automobile parts in order to reduce the weight of automobile bodies due to environmental problems. Press molding, which is excellent in manufacturing cost, is often used for manufacturing automobile parts. However, the high-strength steel sheet has a large elastic recovery (spring back) after forming as compared with the low-strength steel sheet, which makes it difficult to obtain an automobile part having a desired shape by press forming. Therefore, there is a strong demand for development of a press forming method for suppressing springback of automobile parts using a high strength steel sheet.

As an example of springback that occurs in a press-formed molded member, as shown in FIG. 10, a cross section in which a first piece portion 43 and a second piece portion 45 are continuous via a bent portion 47 has a substantially L-shape, When the molding member 41 that curves along the longitudinal direction in a plan view is molded by a mold, the angle θ0 formed by the first piece portion 43 and the second piece portion 45 may increase after mold release.
As a technique for press-molding while suppressing such springback, for example, in Non-Patent Document 1, in order to obtain the dimensional accuracy of members (automobile parts) having a hat-shaped cross-sectional shape, in addition to the molding process, a rest-like process is performed. By adopting a process and making the bending radius of the bending part formed in the rest-like process smaller than the bending radius of the bending part formed in the forming process, a part of the bending part formed in the forming process can be formed in the rest-like process. A method is disclosed in which the web and the flange are bent back and an angle change (spring go element) that closes the bent part inward is generated to improve the angle change of the bent part and suppress springback. ..

Further, in Patent Document 1, for a press-molded part having a U-shaped cross section or a V-shaped cross section, a connecting portion that connects between the surface portions forming the U-shape or the V-shape is formed. By chamfering so that there are two or more curved portions having a curved shape and one or more linear portions having a straight cross-sectional shape, the stress remaining in the linear portion after press forming causes a spring go. There is disclosed a method of suppressing the springback by reducing the angle change amount in the connecting portion.

Japanese Patent No. 4992048

Thin Steel Sheet Forming Technology Study Group, Press Forming Difficult Handbook (4th Edition), Nikkan Kogyo Shimbun, 2017, p.319

As disclosed in Non-Patent Document 1 and Patent Document 1, in a molded member having a substantially L-shaped cross section by bending a metal base plate into a mountain shape, a piece having a substantially L-shaped cross section is formed. In order to suppress the angle change due to the springback of the part connecting the one part, it is effective to mix the spring-go component and the springback component in the connecting part and cancel them to suppress the angle change.
However, the method disclosed in Non-Patent Document 1 requires a restrike process in addition to the molding process, and a molded member that satisfies the dimensional accuracy cannot be molded by a single press molding, resulting in a decrease in productivity. There's a problem. In addition, the method disclosed in Patent Document 1 cannot be applied when the design change in the joint shape is not allowed in the product specifications because the shape of the final product is limited, and the tensile strength exceeds 1180 MPa. When a high-tensile steel plate is used, there is a problem in that the pressing load is insufficient depending on the capacity of the pressing machine, and the linear portion applied to the connecting portion cannot be formed into a sufficiently linear shape.

Furthermore, the methods disclosed in Non-Patent Document 1 and Patent Document 1 have a case where a molded member that is bent into a mountain shape and has a substantially L-shaped cross section has a portion that curves along the longitudinal direction, When there is a portion where the bending angle of the bending (the angle formed by the substantially L-shaped piece and the piece) changes along the longitudinal direction, the influence of the contraction flange or the extension flange due to bending is added, and the longitudinal direction is increased. It was difficult to apply it to the changing part of the body because it was complicated.

The present invention has been made in order to solve the above-mentioned problems, and bends a metal base plate in a mountain shape to form a molding member having a substantially L-shaped cross section, after bending the bending angle of the bending. It is an object of the present invention to provide a die shape determination method for determining the shape of a die to be molded so that the target angle becomes a target angle.

That is, in the present invention, in order to prevent a change in angle due to springback, a plurality of cross-sectional shapes are set in the molding member, and each of the set cross-sectional shapes has a first bent portion at the molding bottom dead center. By setting the radius of curvature R1 and the bending angle α1 and the radius of curvature R2 and the bending angle α2 of the second bent portion at the bottom dead center of molding, after the mold release, the first piece and The angle θ0 formed by the two pieces is a means for achieving the target angle θa, and the radius of curvature R1 of the first bent portion at the forming bottom dead center and the bending angle α1 and the radius of curvature R2 of the second bent portion at the forming bottom dead center By determining the shape of the mold on the basis of the plurality of cross-sectional shapes in which the bending angle α2 is set, it is possible to prevent springback of the molding member molded using the mold after the mold is released.

Here, the change in bending angle of the first bent portion Δγ1 (=α1−β1) and the change in bending angle of the second bent portion Δγ2 (=α2−β2) after the mold having the cross-sectional shape set for the molding member is released from the mold. The following factors (a) to (d) can be mentioned as factors that can be changed in order to cancel the above.
(A) Radius of curvature R1 of the first bent portion at the bottom dead center of molding
(B) The radius of curvature R2 of the second bent portion at the bottom dead center of molding
(C) Bending angle α1 of the first bent portion at the bottom dead center of molding
(D) Bending angle α2 of the second bent portion at the bottom dead center of molding
Further, the target shapes include the following (i) and (ii).
(i) When the second bent portion is on the second piece
(ii) When the first bent portion has the second bent portion When the first bent portion needs to have the target shape or the product shape, the above (a) and (c) will be obtained. Regarding (b) and (d) above, cases (i) and (ii) will be treated as change factors.
In the present application, the above items (a) and (b) were examined.
The present invention also includes the case where the plastic bending due to the suppression of the springback remains on the piece having a substantially L-shaped cross section.

(1) The mold shape determining method according to the present invention comprises bending a metal base plate into a mountain shape to form a molding member having a first piece portion and a second piece portion and having a substantially L-shaped cross section. The shape of a metal mold is determined so that an angle formed by the first piece and the second piece becomes a target angle, and the shape of the molding member is set at a plurality of positions along the ridgeline of the mountain shape. A cross-section shape setting step of setting a cross-section that intersects the ridge line and setting a cross-sectional shape at the molding bottom dead center of the molding member for each of the set cross-sections, and interpolating the set plurality of cross-sectional shapes along the ridge line. A molding bottom dead center shape determining step of determining the shape of the molding member at the molding bottom dead center, and a mold for determining the shape of the mold based on the determined shape of the molding member at the molding bottom dead center A shape-defining step, wherein the cross-section shape setting step is continuous from the first piece, and has a first L-shaped bent portion that has a curvature equal to that of the substantially L-shaped bending and a bending angle larger than that of the bending. A second bent portion that is continuous from the first bent portion and that is bent in the opposite direction to the first bent portion and is connected to the second piece portion is set to each of the cross-sectional shapes, and spring back after release is used. The radius of curvature R1 of the first bent portion at the molding bottom dead center is set to the following step S1 so that the change Δγ1 of the bending angle of the first bent portion and the change Δγ2 of the bending angle of the second bent portion cancel each other. Is obtained in accordance with the procedure from step S9 to step S9.
(S1) Based on the plate thickness and stress-strain relationship of the metal base plate, the radius of curvature R of the bent portion at the forming bottom dead center formed by bending the metal base plate and the bending angle of the bent portion at the forming bottom dead center. The relationship between α and the angle ratio β/α of the bending angle β of the bent portion after release is acquired.
(S3) The bending angle α1 of the first bent portion at the bottom dead center of molding, the radius of curvature R2 and the bending angle α2 of the second bent portion at the bottom dead center of molding are given.
(S5) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α obtained in (S1), the radius of curvature R2 and the bending angle α2 of the second bent portion at the bottom dead center of the molding are used to separate from each other. The bending angle β2 of the second bent portion after the mold is obtained.
(S7) Using the bending angle α2 of the second bent portion at the molding bottom dead center and the bending angle β2 after releasing the mold, and the bending angle α1 of the first bent portion at the molding bottom dead center, The change in the bending angle Δγ1 (=α1−β1) of the first bent portion due to the spring back and the change Δγ2 (=α2−β2) of the bending angle of the second bent portion are equalized and offset. The bending angle β1 of the first bent portion after the mold is calculated.
(S9) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α acquired in (S1), the bending angle α1 of the first bent portion at the bottom dead center of the molding and the first angle after the mold release The radius of curvature R1 of the first bent portion at the bottom dead center of molding is determined from the angle ratio β1/α1 with the bending angle β1 of the first bent portion.

(2) The mold shape determining method according to the present invention comprises bending a metal base plate into a mountain shape to form a molding member having a first piece portion and a second piece portion and having a substantially L-shaped cross section. The shape of a metal mold is determined so that an angle formed by the first piece and the second piece becomes a target angle, and the shape of the molding member is set at a plurality of positions along the ridgeline of the mountain shape. A cross-section shape setting step of setting a cross-section that intersects the ridge line and setting a cross-sectional shape at the molding bottom dead center of the molding member for each of the set cross-sections, and interpolating the set plurality of cross-sectional shapes along the ridge line. A molding bottom dead center shape determining step of determining the shape of the molding member at the molding bottom dead center, and a mold for determining the shape of the mold based on the determined shape of the molding member at the molding bottom dead center A shape determining step, wherein the cross-section shape setting step is continuous from the second piece portion, and has a first bent portion that has a curvature equal to that of the substantially L-shaped bend and a bending angle larger than that of the bend. A second bent portion that is continuous from the first bent portion and is bent in a direction opposite to the first bent portion and connected to the first piece portion is set to each of the cross-sectional shapes, and spring back after releasing the mold is used. The radius of curvature R1 of the first bent portion at the molding bottom dead center is set to the following step S1 so that the change Δγ1 of the bending angle of the first bent portion and the change Δγ2 of the bending angle of the second bent portion cancel each other. Is obtained in accordance with the procedure from step S9 to step S9.
(S1) Based on the plate thickness and stress-strain relationship of the metal base plate, the radius of curvature R of the bent portion at the forming bottom dead center formed by bending the metal base plate and the bending angle of the bent portion at the forming bottom dead center. The relationship between α and the angle ratio β/α of the bending angle β of the bent portion after release is acquired.
(S3) The bending angle α1 of the first bent portion at the bottom dead center of molding, the radius of curvature R2 and the bending angle α2 of the second bent portion at the bottom dead center of molding are given.
(S5) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α obtained in (S1), the radius of curvature R2 and the bending angle α2 of the second bent portion at the bottom dead center of the molding are used to separate from each other. The bending angle β2 of the second bent portion after the mold is obtained.
(S7) Using the bending angle α2 of the second bent portion at the molding bottom dead center and the bending angle β2 after releasing the mold, and the bending angle α1 of the first bent portion at the molding bottom dead center, The change in the bending angle Δγ1 (=α1−β1) of the first bent portion due to the spring back and the change Δγ2 (=α2−β2) of the bending angle of the second bent portion are equalized and offset. The bending angle β1 of the first bent portion after the mold is calculated.
(S9) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α obtained in (S1), the bending angle α1 of the first bent portion at the bottom dead center of molding and the first angle after releasing the mold The radius of curvature R1 of the first bent portion at the molding bottom dead center is determined from the angle ratio β1/α1 with the bending angle β1 of the first bent portion.

(3) The mold shape determining method according to the present invention comprises bending a metal base plate into a mountain shape to form a molding member having a first piece portion and a second piece portion and having a substantially L-shaped cross section. The shape of a metal mold is determined so that an angle formed by the first piece and the second piece becomes a target angle, and the shape of the molding member is set at a plurality of positions along the ridgeline of the mountain shape. A cross-section shape setting step of setting a cross-section that intersects the ridge line and setting a cross-sectional shape at the molding bottom dead center of the molding member for each of the set cross-sections, and interpolating the set plurality of cross-sectional shapes along the ridge line. A molding bottom dead center shape determining step of determining the shape of the molding member at the molding bottom dead center, and a mold for determining the shape of the mold based on the determined shape of the molding member at the molding bottom dead center A shape-defining step, wherein the cross-section shape setting step is continuous from the first piece, and has a first L-shaped bent portion that has a curvature equal to that of the substantially L-shaped bending and a bending angle larger than that of the bending. A second bent portion that is continuous from the first bent portion and that is bent in the opposite direction to the first bent portion and is connected to the second piece portion is set to each of the cross-sectional shapes, and spring back after release is used. The radius of curvature R2 of the second bent portion at the molding bottom dead center is set to the following step S1 so that the change Δγ1 of the bending angle of the first bent portion and the change Δγ2 of the bending angle of the second bent portion cancel each other out. Further, it is characterized in that it is obtained in accordance with the procedure of steps S13 to S19.
(S1) Based on the plate thickness and stress-strain relationship of the metal base plate, the radius of curvature R of the bent portion at the forming bottom dead center formed by bending the metal base plate and the bending angle of the bent portion at the forming bottom dead center. The relationship between α and the angle ratio β/α of the bending angle β of the bent portion after release is acquired.
(S13) The radius of curvature R1 and the bending angle α1 of the first bent portion at the bottom dead center of molding and the bending angle α2 of the second bent portion at the bottom dead center of molding are given.
(S15) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α acquired in (S1), the radius of curvature R1 and the bending angle α1 of the first bent portion at the bottom dead center of the molding are used to separate from each other. The bending angle β1 of the first bent portion after the mold is obtained.
(S17) Using the bending angle α1 of the first bent portion at the molding bottom dead center and the bending angle β1 after the mold release, and the bending angle α2 of the second bent portion at the molding bottom dead center, The change in the bending angle Δγ1 (=α1−β1) of the first bent portion due to the spring back and the change Δγ2 (=α2−β2) of the bending angle of the second bent portion are equalized and offset. The bending angle β2 of the second bent portion after the mold is calculated.
(S19) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α obtained in (S1), the bending angle α2 of the second bent portion at the bottom dead center of the molding and the second angle after mold release The radius of curvature R2 of the second bent portion at the bottom dead center of molding is determined from the angle ratio β2/α2 of the bending angle β2 of the two bent portions.

(4) The mold shape determining method according to the present invention comprises bending a metal base plate into a mountain shape to form a molding member having a first piece portion and a second piece portion and having a substantially L-shaped cross section. The shape of a metal mold is determined so that an angle formed by the first piece and the second piece becomes a target angle, and the shape of the molding member is set at a plurality of positions along the ridgeline of the mountain shape. A cross-section shape setting step of setting a cross-section that intersects the ridge line and setting a cross-sectional shape at the molding bottom dead center of the molding member for each of the set cross-sections, and interpolating the set plurality of cross-sectional shapes along the ridge line. A molding bottom dead center shape determining step of determining the shape of the molding member at the molding bottom dead center, and a mold for determining the shape of the mold based on the determined shape of the molding member at the molding bottom dead center A shape determining step, wherein the cross-section shape setting step is continuous from the second piece portion, and has a first bent portion that has a curvature equal to that of the substantially L-shaped bend and a bending angle larger than that of the bend. A second bent portion that is continuous from the first bent portion and is bent in a direction opposite to the first bent portion and connected to the first piece portion is set to each of the cross-sectional shapes, and spring back after releasing the mold is used. The radius of curvature R2 of the second bent portion at the molding bottom dead center is set to the following step S1 so that the change Δγ1 of the bending angle of the first bent portion and the change Δγ2 of the bending angle of the second bent portion cancel each other out. Further, it is characterized in that it is obtained in accordance with the procedure of steps S13 to S19.
(S1) Based on the plate thickness and stress-strain relationship of the metal base plate, the radius of curvature R of the bent portion at the forming bottom dead center formed by bending the metal base plate and the bending angle of the bent portion at the forming bottom dead center. The relationship between α and the angle ratio β/α of the bending angle β of the bent portion after release is acquired.
(S13) The radius of curvature R1 and the bending angle α1 of the first bent portion at the bottom dead center of molding and the bending angle α2 of the second bent portion at the bottom dead center of molding are given.
(S15) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α acquired in (S1), the radius of curvature R1 and the bending angle α1 of the first bent portion at the bottom dead center of the molding are used to separate from each other. The bending angle β1 of the first bent portion after the mold is obtained.
(S17) Using the bending angle α1 of the first bent portion at the molding bottom dead center and the bending angle β1 after the mold release, and the bending angle α2 of the second bent portion at the molding bottom dead center, The change in the bending angle Δγ1 (=α1−β1) of the first bent portion due to the spring back and the change Δγ2 (=α2−β2) of the bending angle of the second bent portion are equalized and offset. The bending angle β2 of the second bent portion after the mold is calculated.
(S19) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α obtained in (S1), the bending angle α2 of the second bent portion at the bottom dead center of the molding and the second angle after mold release The radius of curvature R2 of the second bent portion at the bottom dead center of molding is determined from the angle ratio β2/α2 of the bending angle β2 of the two bent portions.

(5) In any one of the above (1) to (4), the molding member has a curved portion that curves along the longitudinal direction, and the cross-sectional shape setting step is a cross-section of the curved portion. It is characterized in that at least one shape is set.

(6) In any one of the above (1) to (5), the molding member has a portion in which the bending angle of the substantially L-shaped bending changes along the ridgeline of the mountain shape. The cross-sectional shape setting step sets at least cross-sectional shapes at both end positions in the direction along the ridge of the portion where the bending angle changes, and the bending angle has an extreme value at the portion where the bending angle changes. In this case, the sectional shape at the position of the extreme value is further set.

According to the present invention, a metal base plate is bent into a mountain shape, and a molding member having a first piece portion and a second piece portion and having a substantially L-shaped cross section is provided as the first piece portion and the second piece. The shape of the mold is determined so that the angle formed by the part becomes a target angle, and a cross section that intersects the ridgeline is set at a plurality of positions along the ridgeline of the mountain shape for the forming member, A cross-sectional shape setting step of setting a cross-sectional shape at the forming bottom dead center of the forming member for each set cross section, and a plurality of set cross-sectional shapes are interpolated along the ridge line to form the forming bottom dead center of the forming member. A molding bottom dead center shape determining step for determining the shape in, and a mold shape determining step for determining the shape of the mold based on the shape at the molding bottom dead center of the determined molding member, The cross-sectional shape setting step is continuous from the first piece portion, and is continuous from the first bent portion and a first bent portion that has a curvature substantially equal to that of the substantially L-shaped bend and a bending angle larger than that of the bend, A second bent portion that bends in the opposite direction to the first bent portion and is connected to the second piece portion is set to each of the cross-sectional shapes, and the bending angle of the first bent portion due to springback after release from the mold is set. By determining and setting the radius of curvature R1 of the first bent portion at the bottom dead center of the molding so that the change Δγ1 and the change Δγ2 of the bending angle of the second bent portion cancel each other, the springback after mold release is set. It is possible to determine the shape of a mold that can efficiently form a molding member having excellent shape fixability by one press molding while suppressing the above. Further, even when the molding member has a portion that curves along the longitudinal direction, or when the bending angle of the bending has a portion that changes along the longitudinal direction of the molding member, the mold releasing of the molding member is performed. It is possible to determine the shape of the mold that can be formed while suppressing the springback afterwards.

It is a flowchart which shows the procedure which determines the shape of a metal mold in the metal mold shape determination method which concerns on this Embodiment. It is a figure explaining the shape in the shaping|molding bottom dead center of a shaping|molding member in the die shape determination method which concerns on this Embodiment ((a) perspective view, (b) sectional view) (the 1). It is a figure explaining the shape in the shaping|molding bottom dead center of a shaping|molding member in the die shape determination method which concerns on this Embodiment ((a) perspective view, (b) sectional view) (the 2). It is a figure explaining the cross section which crosses the ridgeline of the shaping member concerning this embodiment, and the section shape in the section ((a) top view, (b) perspective view). It is a figure which shows the shape in the shaping|molding bottom dead center of the shaping|molding member determined by interpolating a cross-sectional shape in the die shape determination method which concerns on this Embodiment. In Embodiment 1 of the present invention, it is a flow diagram showing a procedure for obtaining the radius of curvature of the first bent portion by giving the bending angle of the first bent portion, the radius of curvature of the second bent portion, and the bending angle. In Embodiment 1 and Embodiment 2, it is a figure explaining the curvature radius in the shaping|molding bottom dead center of the bending part which bent the metal base plate, the bending angle in shaping|molding bottom dead center, and the bending angle after mold release. 7 is a graph showing a relationship between a radius of curvature of a bent portion obtained by bending a metal base plate and an angle ratio of a bending angle in the first and second embodiments. FIG. 10 is a flow chart showing a procedure of obtaining a radius of curvature of a second bent portion by giving a radius of curvature and a bend angle of a first bent portion and a bend angle of a second bent portion in the second embodiment. It is a figure explaining the spring back which arises in the forming member which has the section where the section formed by the conventional press forming method has abbreviation L shape.

In the mold shape determining method according to the embodiment of the present invention, a metal base plate is bent into a mountain shape as shown in FIG. 10 as an example, and the first piece 43 and the second piece 45 are bent. When the molding member 41 is connected via 47 and has a substantially L-shaped cross-section, the angle θ 0 formed by the first piece portion 43 and the second piece portion 45 is formed to be the target angle. It determines the shape.

As described above, the molded member 41 undergoes springback after the mold release, in which the angle θ0 formed by the first piece portion 43 and the second piece portion 45 increases. Therefore, in the mold shape determining method according to the present embodiment, the shape of the mold for molding the molding member 1 having the shape shown in FIG. The angle θ0 formed by the first piece 3 and the second piece 5 is set to the target angle.

The forming member 1 has a first piece part 3 and a second piece part 5 formed by bending a metal base plate into a mountain shape and has a substantially L-shaped cross section. As shown in FIG. 2, the shape at the point is a first bent portion 7 continuous from the first piece portion 3 and a second bent portion 9 continuous from the first bent portion 7 and connected to the second piece portion 5. Have. The first bent portion 7 is bent in the substantially L shape, that is, bent in the same direction as the bent portion 47 (FIG. 10) of the molding member 41, has the same curvature as the bent portion 47, and has a bending angle larger than that of the bent portion 47. Is set to be large, whereas the second bent portion 9 is set to have a curvature and a bending angle so that the second bent portion 9 bends in a direction opposite to the first bent portion 7.
Here, the bending angle of the bent portion 47 and the bending angle of the first bent portion 7 and the second bent portion 9 correspond to the central angle of the arc of each bent portion.

As shown in FIG. 10, when the target forming member 41 is curved along the longitudinal direction in a plan view and the mountain-shaped ridge line L has a shape along the curve, the molding member 1 is As shown in FIG. 2, the shape at the dead point may be a shape in which the first bent portion 7 including the ridge line L and the second bent portion 9 continuous with the first bent portion 7 are along the ridge line L.
Further, when the angle θ0 formed by the first piece portion 43 and the second piece portion 45 of the molding member 41 is constant along the longitudinal direction of the molding member 41, the shape of the molding member 1 at the molding bottom dead center is The curvature and bending angle of each of the first bent portion 7 and the second bent portion 9 may be set to be constant along the longitudinal direction.

Furthermore, the present invention may determine the shape of the mold for molding the molding member 11 having the shape shown in FIG. 3 at the molding bottom dead center. The forming member 11 has a first piece portion 13 and a second piece portion 15 formed by bending a metal base plate into a mountain shape and has a substantially L-shaped cross section. As shown in FIG. 3, the shape in 1 has a first bent portion 17 continuous from the second piece portion 15 and a second bent portion 19 continuous from the first bent portion 17 and connected to the first piece portion 13. Have. The first bent portion 17 is bent in the same direction as the substantially L-shaped bent portion (bent portion 47 in FIG. 10), has the same curvature as the bent portion 47, and has a larger bending angle than the bent portion 47. On the other hand, the curvature and bending angle of the second bent portion 19 are set so as to bend in the direction opposite to the first bent portion 17.
Hereinafter, unless otherwise specified, the mold shape determining method according to the present embodiment will be described for the case of determining the shape of the mold for molding the molding member 1 having the shape shown in FIG. 2 at the molding bottom dead center. ..

The mold shape determining method according to the present embodiment is configured such that a metal blank is bent into a mountain shape as shown in FIG. 2, and the first piece portion 43 and the second piece portion 45 have a substantially L-shaped cross section. The shape of the mold for molding the molding member 41 having is determined so that the angle θ0 formed by the first piece portion 43 and the second piece portion 45 becomes the target angle, and as shown in FIG. The cross-sectional shape setting step P1, the molding bottom dead center shape determining step P3, and the mold shape determining step P5 are included. Hereinafter, each of the above steps will be described.

<Cross section shape setting process>
The cross-sectional shape setting step P1 sets cross-sections that intersect the ridge line L at a plurality of positions along the ridge line L of the mountain shape of the molding member 1, and for each of the set cross-sections, the cross-sectional shape at the molding bottom dead center of the molding member 1. 4A, a plurality of cross sections Ca, Cb, Cc orthogonal to the ridge line L are set at a plurality of positions along the ridge line L of the mountain shape in the molding member 1 in FIG. As shown in (b), the cross-sectional shapes Sa, Sb, Sc at the molding bottom dead center of the molding member 1 are set for each of the set cross-sections Ca, Cb, Cc.

Then, as shown in FIG. 5A, first bent portions 7a, 7b and 7c and second bent portions 9a, 9b and 9c are set in the cross-sectional shapes Sa, Sb and Sc, respectively.
The first bent portions 7a, 7b and 7c are continuous from the first piece portion 3 and have the same curvature as the substantially L-shaped bending of the molding member 1 and are set to have a larger bending angle than the bending. .. On the other hand, the second bent portions 9a, 9b and 9c are continuous from the first bent portions 7a, 7b and 7c, respectively, and are bent in the opposite direction to the first bent portions 7a, 7b and 7c and continuous to the second piece portion 5. Is set to.

Further, in the cross-sectional shape setting step P1, for each cross-sectional shape Sa, Sb and Sc, the elastic recovery from the bending angle α1 at the molding bottom dead center of each of the first bending portions 7a, 7b and 7c to the bending angle β1 after releasing from the mold. Change in bending angle due to Δγ1 (=α1−β1) and change in bending angle due to elastic recovery from the bending angle α2 at the bottom dead center of the molding of each of the second bent portions 9a, 9b and 9c to the bending angle β2 after releasing from the mold. By offsetting Δγ2 (=α2-β2), it is possible to prevent the angle change of the angle θ0 formed by the first piece 3 and the second piece 5 after the mold is released and to achieve the target angle θa. From the bending angle α1 of the first bent portions 7a, 7b, 7c at the bottom dead center and the bending angle α2 and the curvature radius R2 of the second bent portions 9a, 9b, 9c at the molding bottom dead center, The radius of curvature R1 of the bent portions 7a, 7b and 7c is calculated for each of the sectional shapes Sa, Sb and Sc. Alternatively, from the bending radius R1 and the bending angle α1 of the first bent portions 7a, 7b, 7c at the molding bottom dead center and the bending angle α2 of the second bent portions 9a, 9b, 9c at the molding bottom dead center, The radius of curvature R2 of the second bent portions 9a, 9b, and 9c at is obtained for each of the sectional shapes Sa, Sb, and Sc.

A specific procedure for obtaining the radius of curvature R1 of the first bent portions 7a, 7b and 7c at the molding bottom dead center is described in Embodiment 1 described later in the radius of curvature R2 of the second bent portions 9a, 9b and 9c at the molding bottom dead center. A specific procedure for obtaining the value will be specifically described in Embodiment 2 described later.

<Molding bottom dead center shape determination process>
In the forming bottom dead center shape determining step P3, as shown in FIG. 5B, the plurality of sectional shapes Sa, Sb, and Sc set in the sectional shape setting step P1 are interpolated along the ridge line L to form the forming member 1. This is a step of determining the shape at the bottom dead center of molding.

For the interpolation of the plurality of cross-sectional shapes Sa, Sb and Sc, for example, spline interpolation can be used. However, the interpolation algorithm is not limited to spline interpolation, and may be Lagrange interpolation, Newton interpolation, or any other algorithm that can smoothly interpolate a cross-sectional shape along a ridge.
Further, in determining the shape of the molding member 1 at the bottom dead center of molding, both end positions of the ridge line L along the longitudinal direction may be set in advance and the cross-sectional shapes Sa, Sb and Sc may be interpolated.

<Mold shape determination process>
The mold shape determining step P5 is a step of determining the shape of the mold based on the shape (FIG. 5B) of the molding member 1 at the molding bottom dead center determined in the molding bottom dead center shape determining step P3. ..
The shape of the mold can be determined in consideration of, for example, the thickness of the metal base plate and the clearance with the mold.

As described above, the molding of the molding member 1 determined by setting the first bent portions 7a, 7b and 7c and the second bent portions 9a, 9b and 9c in the cross-sectional shapes Sa, Sb and Sc intersecting the ridge L, respectively. By determining the shape of the mold based on the shape at the dead point, the following operational effects are achieved. In addition, in the following description, the first bent portion 7a and the second bent portion 9a are set in the cross-sectional shape Sa, but the same operational effect is also obtained in the cross-sectional shapes Sb and Sc.

In the cross-sectional shape Sa, the first bending portion 7a and the second bending portion 9a have bending directions reversed to each other (see FIG. 2 ), so that the first bending portion 7a and the second bending portion 9a are not At, the angle changes due to elastic recovery occur in opposite directions.
Here, since the first bending portion 7a is bent in the same direction as the target angle, the change from the bending angle α1 of the first bending portion 7a at the molding bottom dead center to the bending angle β1 after the mold release is the first It serves as a springback component that increases the angle θ0 formed by the one piece 3 and the second piece 5. On the other hand, since the second bent portion 9a is bent in the direction opposite to the first bent portion 7a, the change from the bending angle α2 of the second bending portion 9 at the molding bottom dead center to the bending angle β2 after the mold release. Is a spring-go component that reduces the angle θ0 formed by the first piece 3 and the second piece 5.

As a result, in the cross-sectional shape Sa after release, if the springback component of the first bent portion 7a and the spring go component of the second bent portion 9a can be offset, that is, the change of the bending angle of the first bent portion 7a. If Δγ1 (=α1−β1) is equal to the change Δγ2 (=α2−β2) in the bending angle of the second bent portion 9a, the angle θ0 formed by the first piece 3 and the second piece 5 in the sectional shape Sa is The change in angle is prevented and the target angle θa is reached, and the change in bending angle due to springback can be prevented.

Also in the cross-sectional shape Sb, similarly to the cross-sectional shape Sa, the first bent portion 7b and the second bent portion 9b are set, and the angle change of the first bent portion 7b and the angle change of the second bent portion 9b after releasing the mold are performed. By making them equal, it is possible to prevent the angle change of the angle θ0 formed by the first piece 3 and the second piece 5 even in the cross-sectional shape Sb. Also in the cross-sectional shape Sc, the first bent portion 7c and the second bent portion 9c are set so that the angle change of the first bent portion 7c and the angle change of the second bent portion 9c after releasing the mold are equal. Thus, even in the cross-sectional shape Sc, the angle change of the angle θ0 formed by the first piece portion 3 and the second piece portion 5 can be prevented.

Then, the cross-sectional shapes Sa, Sb, and Sc set in this way are interpolated along the ridge line L to determine the shape of the molding member 1 at the bottom dead center of molding, so that the spring of the entire molding member 1 after release from the mold is released. The shape of the mold that can prevent backing can be determined.

Even when determining the shape of the mold for molding the molding member 11 having the first piece portion 13 and the second piece portion 15 and having a substantially L-shaped cross section, as shown in FIG. At the dead point, a first bent portion 17 that is continuous from the second piece portion 15 and has a curvature equal to that of the substantially L-shaped bent portion (bent portion 47 in FIG. 10) and a bending angle larger than that of the first bent portion 17; By setting the second bent portion 19 that is continuous from the bent portion 17 and is bent in the direction opposite to the first bent portion 17 and connected to the second piece portion 15, the first piece portion 3 and the second piece portion 5 are formed. The angle θ0 is prevented from changing and the target angle θa is obtained, so that springback in the molding member 11 can be prevented.

Next, in the cross-sectional shape setting step P1, the procedure for obtaining the radius of curvature R1 of the first bent portions 7a, 7b and 7c at the forming bottom dead center is described in the first embodiment, and the second bent portions 9a, 9b at the forming bottom dead center and A procedure for obtaining the radius of curvature R2 of 9c will be described in the second embodiment.

[Embodiment 1]
In the sectional shape setting step P1, referring to FIG. 2 and FIG. 5, when setting the first bent portion 7a and the second bent portion 9a in the sectional shape Sa, the curvature radius R1 of the first bent portion 7a at the molding bottom dead center is set. Is the bending angle α1 of the first bent portion 7a at the bottom dead center of the molding, and the radius of curvature R2 and the bending angle α2 of the second bent portion 9a at the bottom dead center of the molding, thereby giving steps S1 to S9 shown in FIG. Can be obtained by following the procedure in. Hereinafter, when forming the forming member 1 shown in FIG. 2 using a steel plate having a steel plate strength of 980 MPa as the metal base plate, the angle θ0 formed by the first piece 3 and the second piece 5 is the target angle θa=120°. Each step of steps S1 to S9 will be described by taking the case of molding as described above as an example.

In the following description, the radius of curvature R1 of the first bent portion 7a set to the cross-sectional shape Sa is calculated, but when the first bent portion 7b and the second bent portion 9b are set to the cross-sectional shape Sb, Even when the first bent portion 7c and the second bent portion 9c are set in the cross-sectional shape Sc, the radius of curvature R1 of each of the first bent portions 7b and 7c can be obtained by the same procedure. Further, for the molding member 11 in which the second bent portion 19 is connected to the first piece portion 13 as shown in FIG. 3, the curvature radius R1 of the first bent portion 17 at the molding bottom dead center is obtained by the same procedure. be able to.

<Step S1>
In step S1, as shown in FIG. 7, the metal base plate 31 is bent and molded by the mold 21 including the die 23 and the punch 25 by using the plate thickness and the stress-strain relationship of the metal base plate. The relationship between the radius of curvature R of the bent portion 33 at the bottom dead center, the bending angle α of the bent portion 33 at the molding bottom dead center, and the angle ratio β/α of the bending angle β after the mold release is acquired.

FIG. 8 shows the relationship between the radius of curvature R and the angle ratio β/α of the bent portion 33 in which a steel plate having a tensile strength of 980 MPa and a plate thickness of 1.4 mm is bent as the metal base plate 31.
FIG. 8 is an example obtained by theoretical calculation based on a publicly known reference document (Plastic Working Society ed.: “Bending”, Corona Publishing Co., Ltd. (1995), p.23). In the theoretical calculation, the bending portion 33 is used. The angle ratio β/α of is calculated by the following equation (1) which is a modification of the equation (1.46) in the reference.

Here, n is a work hardening coefficient, and λ _e is given by the following equation (2) (equation (1.17) in the above reference).

Here, r _m is (the radius of curvature R of = the bending portion 33), t ₀ the curvature of the plate thickness center plane radius thickness, sigma _e is the yield stress, E is the Young's modulus, the curvature radius R shown in FIG. 8 And the angle ratio β/α, the plate thickness t ₀ =1.4 mm, the yield stress σ _e =850 MPa, the Young's modulus E=210 GPa, and the work hardening coefficient n=0.12 are substituted into the equations (1) and (2). It was sought after.

The relationship between the radius of curvature R of the bent portion 33 and the angle ratio β/α is not limited to that obtained by the above-described theoretical calculation. For example, a molding analysis for molding the bent portion 33 to the molding bottom dead center (FIG. 7). The steps (a) to (b)) and the springback analysis (steps of FIGS. 7B to 7C) after releasing the molded bent portion 33 from the mold 21 are performed by finite element analysis. It may be one that does.

When the relationship between the radius of curvature R of the bent portion 33 and the angle ratio β/α is obtained by finite element analysis, the type of the metal base plate 31 (steel type when using a steel plate) and the plate thickness t ₀ are set to a constant _value. Molding analysis and springback analysis may be performed by variously changing the radius of curvature R of the bent portion 33 at the dead center and the bending angle α of the molding bottom dead center (mold shape). In the finite element analysis, the width of the metal base plate 31 (length in the depth direction with respect to the paper surface) does not matter, and an arbitrary value can be set appropriately.
Further, in the actual experiment, the bending angle R of the bending portion 33 and the bending angle α of the molding bottom dead center (mold shape) are changed to obtain the bending angle β after release from the mold, not by the finite element analysis described above. Then, the relationship between the radius of curvature R of the bent portion 33 and the angle ratio β/α may be acquired.

<Step S3>
In step S3, the bending angle α1 of the first bent portion 7a at the bottom dead center of the molding, and the radius of curvature R2 and the bending angle α2 of the second bent portion 9a at the bottom dead center of the molding are given.
The angle θ0 formed by the first piece 3 and the second piece 5 at the bottom dead center of the molding is a geometry for rotating the first piece 3 by the bending angle α2 while maintaining the bending angle α1 of the first bent portion 7a. From the geometrical relationship, the bending angle α1 of the first bent portion 7a at the bottom dead center of the molding and the bending angle α2 of the second bent portion 9a at the bottom dead center of the molding have a relationship of θ0=π−α1+α2.

In the first embodiment, from the above relationship, in order to set the angle θ0 formed by the first piece 3 and the second piece 5 to the target angle θa=120°, the first bent portion 7a at the molding bottom dead center is When the bending angle α1=100° is given, the bending angle α2 of the second bent portion 9a at the molding bottom dead center is α2=40°. Further, the radius of curvature R2 of the second bent portion 9a is set to R2=60 mm.

<Step S5>
In step S5, the radius of curvature R2 and the bending angle α2 of the second bent portion 9a at the molding bottom dead center are used by using the relationship between the radius of curvature R of the bent portion 33 and the angle ratio β/α acquired in (S1). Thus, the bending angle β2 of the second bent portion 9a after releasing the mold is obtained.
In the first embodiment, the bending angle β2 of the second bent portion 9a after the mold release is the radius of curvature R2 of the second bent portion 9a at the molding bottom dead center R2=60 mm, and the bending of the second bent portion 9a at the molding bottom dead center. Since the angle is α2=40°, from the relationship between the radius of curvature R and the angle ratio β/α shown in FIG. 7, the bending angle β2=α2×0.45=18° of the second bent portion 9a after releasing the mold. ..

<Step S7>
In order to prevent the change of the angle due to the spring back, the change Δγ1 (=α1−β1) of the bending angle of the first bent portion 7a and the change Δγ2 (=α2−β2) of the bending angle of the second bent portion 9a cancel each other. All that has to be done is that they are equal. Therefore, in step S7, the bending angle α2 of the second bent portion 9a at the bottom dead center of the molding, the bending angle β2 of the second bent portion 9a after the mold release, and the bending angle of the first bent portion 7a at the bottom dead center of the molding. α1 is used to make the change Δγ1 (=α1−β1) in the bending angle of the first bent portion 7a and the change Δγ2 (=α2−β2) in the bending angle of the second bent portion 9a equal to each other. The bending angle β1 of the bent portion 7a after releasing the mold is calculated.

In the first embodiment, the change Δγ2 (=α2-β2) in the bending angle of the second bent portion 9a is Δγ2=40-18=22°, and the bending angle α1 of the first bent portion 7a at the molding bottom dead center is 1. Is 100°, the bending angle β1 of the first bent portion 7a after releasing from the mold is 78° from the relationship of Δγ2=22°=Δγ1=α1-β1=100-β1.

<Step S9>
In step S9, the bending angle α1 of the first bent portion 7a at the molding bottom dead center and the post-mold release are used by using the relationship between the radius of curvature R of the bent portion 33 and the angle ratio β/α obtained in (S1). The radius of curvature R1 of the first bent portion 7a at the bottom dead center of molding is determined by the angle ratio β1/α1 with the bending angle β1 of the first bent portion 7a.
In the first embodiment, the bending angle α1 of the first bending portion 7a at the bottom dead center of the molding is 100° and the bending angle β1 after releasing the mold is 78°. Therefore, the angle ratio β1/α1 is 78/100= It is 0.78, and the radius of curvature R1 of the first bent portion 7a at the bottom dead center of molding is determined as R1=20 mm from the relationship of FIG.

As described above, in the sectional shape setting step P1 according to the first embodiment, regarding the sectional shape Sa at the molding bottom dead center of the molding member 1, the bending angle α1 of the first bent portion 7a is 100° and the second bent portion 9a is By giving the radius of curvature R2=60 mm and the bending angle α2=40°, the radius of curvature R1 of the first bent portion 7a is determined to be R1=20 mm. By setting the bent portion 9a, the angle change of the first bent portion 7a and the angle change of the second bent portion 9a after mold release are canceled out, and the angle formed by the first piece 3 and the second piece 5 is canceled. A sectional shape Sa is set so that θ0 can be set to a target angle θa=120°.

[Embodiment 2]
In setting the first bent portion 7a and the second bent portion 9a in the sectional shape Sa in the sectional shape setting step P1, the radius of curvature R2 of the second bent portion 9a at the molding bottom dead center is the first at the molding bottom dead center. By giving the radius of curvature R1 and the bending angle α1 of the bent portion 7a and the bending angle α2 of the second bent portion 9a at the molding bottom dead center, it is possible to obtain the values according to the procedure of step S1 and step S13 to step S19 shown in FIG. it can. Hereinafter, when forming the forming member 1 shown in FIG. 2 using a steel plate having a steel plate strength of 980 MPa as the metal base plate, the angle θ0 formed by the first piece 3 and the second piece 5 is the target angle θa=105°. Each step of step S1 and step S13 to step S19 will be described by taking the case of molding as described above as an example.

In the following description, the radius of curvature R2 of the second bent portion 9a set to the cross-sectional shape Sa is calculated, but when the first bent portion 7b and the second bent portion 9b are set to the cross-sectional shape Sb, Even when the first bent portion 7c and the second bent portion 9c are set in the cross-sectional shape Sc, the radius of curvature R1 of each of the first bent portions 7b and 7c can be obtained by the same procedure. Further, for the molding member 11 in which the second bent portion 19 is connected to the first piece portion 13 as shown in FIG. 3, the curvature radius R2 of the second bent portion 19 at the molding bottom dead center is obtained by the same procedure. be able to.

<Step S1>
Similar to Embodiment 1 described above, in step S1, the metal base plate 31 provided with the die 23 and the punch 25 is bent using the plate thickness of the metal base plate and the stress-strain relationship, as shown in FIG. The relationship between the radius of curvature R of the bent portion 33 at the molding bottom dead center formed by molding, the bending angle α of the bent portion 33 at the molding bottom dead center, and the angle ratio β/α of the bending angle β after mold release is acquired.

In FIG. 8, the metal base plate 31 has a tensile strength of 980 MPa class, a plate thickness of 1.4 mm, a yield stress σ _e =850 MPa, a Young's modulus E=210 GPa, and a radius of curvature of a bent portion 33 in which a work hardening coefficient n=0.12 is bent. The relationship between R and the angle ratio β/α is shown.

<Step S13>
In step S13, the radius of curvature R1 and the bending angle α1 of the first bent portion 7a at the bottom dead center of molding and the bending angle α2 of the second bent portion 9a at the bottom dead center of molding are given.
The angle θ0 formed by the first piece 3 and the second piece 5 at the bottom dead center of the molding is a geometry for rotating the first piece 3 by the bending angle α2 while maintaining the bending angle α1 of the first bent portion 7a. From the geometrical relationship, the bending angle α1 of the first bent portion 7a at the bottom dead center of the molding and the bending angle α2 of the second bent portion 9a at the bottom dead center of the molding have a relationship of θ0=π−α1+α2.

In the second embodiment, when the bending angle α1 of the first bent portion 7a at the bottom dead center of molding is given as 90°, the bending angle α2 of the second bent portion 9a at the bottom dead center of molding becomes α2=15°. Further, the radius of curvature R1 of the first bent portion 7a is set to 15 mm.

<Step S15>
In step S15, the radius of curvature R1 and the bending angle of the first bent portion 7a at the molding bottom dead center are calculated using the relationship between the radius of curvature R of the bent portion 33 and the angle ratio β/α acquired in (S1). From α1, the bending angle β1 of the first bent portion 7a after release is determined.
In the second embodiment, the bending angle β1 of the first bent portion 7a after releasing the mold is as follows: the radius of curvature R1 of the first bent portion 7a at the molding bottom dead center R1=15 mm, and the bending of the first bent portion 7a at the molding bottom dead center. Since the angle α1=90°, the bending angle β1=α1×0.84=75.6° of the first bent portion 7a after releasing from the mold is obtained from the relationship between the radius of curvature R and the angle ratio β/α shown in FIG.

<Step S17>
In order to prevent the change of the angle due to the spring back, the change Δγ1 (=α1−β1) of the bending angle of the first bent portion 7a and the change Δγ2 (=α2−β2) of the bending angle of the second bent portion 9a cancel each other. All that has to be done is that they are equal. Therefore, in step S17, the bending angle α1 of the first bent portion 7a at the bottom dead center of the molding, the bending angle β1 of the first bent portion 7a after release from the mold, and the bending angle of the second bent portion 9a at the bottom dead center of the molding. α2 is used to make the change Δγ1 (=α1−β1) of the bending angle of the first bending portion 7a and the change Δγ2 (=α2−β2) of the bending angle of the second bending portion 9a equal to each other. The bending angle β2 of the bent portion 9a after releasing the mold is calculated.
In the second embodiment, the change ΔΔ1 (=α1−β1) in the bending angle of the first bent portion 7a is Δγ1=90−75.6=14.4°, and the bending angle α2 of the second bent portion 9a is 15°. Therefore, from Δγ1=Δγ2=14.4°=α2-β2=15-β2, the bending angle β2 of the second bent portion 9a after the mold release is 0.6°.

<Step S19>
In step S19, using the relationship between the radius of curvature R of the bent portion 33 and the angle ratio β/α acquired in (S1), the bending angle α2 of the second bent portion 9a at the molding bottom dead center and the post-mold release The radius of curvature R2 of the second bent portion 9a at the bottom dead center of the molding is determined from the angle ratio β2/α2 of the second bent portion 9a to the bending angle β2.
In the second embodiment, the bending angle α2 of the second bent portion 9a at the bottom dead center of the molding is 15° and the bending angle β2 after releasing the mold is 0.6°. Therefore, the angle ratio β2/α2 is 0.6/15= It is 0.04, and the radius of curvature R2 of the second bent portion 9a at the bottom dead center of molding is determined as R2=113 mm from FIG.

As described above, in the sectional shape setting step P1 according to the second embodiment, with respect to the sectional shape Sa of the molding member 1 at the molding bottom dead center, the radius of curvature R1 of the first bent portion 7a is R1=15 mm, and the bending angle is α1=100°. By giving the bending angle α2=15° of the second bent portion 9a, the radius of curvature R2 of the second bent portion 9a is calculated as R2 =113 mm, and using the obtained radius of curvature and bending angle, By setting the two bent portions 9a, the change in the angle of the first bent portion 7a and the change in the angle of the second bent portion 9a after the mold release are offset, and the first piece 3 and the second piece 5 form A sectional shape Sa is set so that the angle θ0 can be made the target angle θa=105°.

In the first and second embodiments described above, when the second bent portions 9a, 9b and 9c are set to have a bent shape in the plastic deformation region for each of the sectional shapes Sa, Sb and Sc, the sectional shapes Sa, Sb and Sc are set. When the shape of the molding member 1 at the bottom dead center of molding is determined by interpolating, the shape of the second bent portion 9 remains after the mold release.
Therefore, for each of the cross-sectional shapes Sa, Sb, and Sc, the second bent portion 9 at the molding bottom dead center is set to have a shape bent in the elastic deformation region, so that the second bent portion 9 is elastically recovered after releasing from the mold. It is preferable that the shape does not remain.

For example, in order to make the second bent portion 9a set in the sectional shape Sa bend in the elastic deformation region, the radius of curvature R2 of the second bent portion 9a at the molding bottom dead center is set to a value equal to or larger than the elastic deformation region ( In the relationship between the radius of curvature R and the angle ratio β/α shown in FIG. 8, R=117 mm or more), and the target angle θa and the bending angle α1 of the first bent portion 7a at the molding bottom dead center and the molding bottom dead center. By setting the relationship between the second bent portion 9a and the bending angle α2 to satisfy θa=α1+α2, the second bent portion 9a after release from the mold can be elastically restored to a planar shape. Since the elastic deformation region differs depending on the type of the metal blank, the radius of curvature R2 of the second bent portion 9a at the bottom dead center of the molding has a relationship between the radius of curvature R acquired in each metal blank and the angle ratio β/α. In, the value of the elastic deformation area may be set.

The reason why θa=α1+α2 is as follows. In each cross-sectional shape, when the bending angle α2 of the second bending portion 9 at the bottom dead center of the molding is elastically deformed by the angle difference Δα2 due to the spring back, the bending angle β2 of the second bending portion 9 after releasing becomes 0°. Therefore, β2=α2-Δα2=0 to α2=Δα2. On the other hand, the bending angle α1 of the first bent portion 7 at the bottom dead center of the molding increases by the elastic difference due to the angular difference Δα1 to become the bending angle β1 of the first bent portion 7 after release, and β1=α1+Δα1. Then, in order to reach the target angle θa after the mold release, the return angle difference Δα1 due to the spring back (elastic deformation) and the angle difference Δα2 increasing due to the spring back (elastic deformation) need to be equal.
As a result, β1=α1+Δα1=α1+Δα2=α1+α2 holds, and the bending angle β1 of the first bending portion 7 after release is required to be in the state without springback, that is, the target angle θa. Therefore, β1= θa=α1+α2.
From the above, if this condition “θa=α1+α2” and the radius of curvature R2 of the second bent portion 9 where β2/α2 are in the elastic region are satisfied, springback can be prevented by applying elastic deformation.

Further, in step S3 of the first embodiment or step S13 of the second embodiment, instead of the bending angle α1 of the first bent portion 7 at the molding bottom dead center, the first piece 3 and the second piece 3 at the molding bottom dead center are formed. When the angle θ0 formed by the piece 5 is given, the geometric relationship of rotating the first piece 3 by the bending angle α2 while keeping the bending angle α1 of the first bending portion 7 (θ0=π−α1+α2) Therefore, the bending angle α1 of the first bent portion 7 at the molding bottom dead center may be obtained by using the bending angle α2 of the second bent portion 9 at the molding bottom dead center.

Further, in step S3 of the first embodiment or step S13 of the second embodiment, instead of the bending angle α2 of the second bent portion 9 at the molding bottom dead center, the first piece 3 and the second piece 3 at the molding bottom dead center are formed. When the angle θ0 formed by the piece 5 is given, the bending angle α1 of the first bent portion 7 at the bottom dead center of the molding is used to move the first piece 3 while keeping the bending angle α1 of the first bent portion 7. The bending angle α2 of the second bent portion 9 at the molding bottom dead center may be obtained from the geometrical relationship of rotating by the bending angle α2 (θ0=π−α1+α2).

In the first and second embodiments, the angle θ0 formed by the first piece 3 and the second piece 5 is molded to the target angle θa=120° or 105°. In the mold shape determining method according to the above, the target angle of the molding member 41 is not limited to this value, and may be appropriately set according to the shape of the molding member to be molded.

Furthermore, according to the present invention, it is possible to determine the shape of a mold that can be molded at a target angle of 90°, which was difficult to mold while suppressing springback in the conventional mold.
That is, when molding the molding member 41 in which the first piece portion 43 and the second piece portion 45 are connected to each other through the bent portion 47 as shown in FIG. , When the angle θ0 formed by the first piece portion 43 and the second piece portion 45 is to be formed at a target angle of 90°, the angle θ0 formed by the first piece portion 43 and the second piece portion 45 in anticipation of springback. When the setting is set, the angle θ0 at the bottom dead center of molding becomes a negative angle of less than 90°, which makes it difficult to remove the molding member from the die (punch) after molding.

On the other hand, according to the mold shape determining method of the present invention, the molding bottom deadening is performed so that the angle θ0 formed by the first piece 3 and the second piece 5 maintains the target angle (=90°). To determine the radius of curvature R2 of the second bent portion 9 from the radius of curvature R1 and the bending angle α1 of the first bent portion 7 and the bending angle α2 of the second bent portion 9 at the point, or the first bent portion at the molding bottom dead center. Since the radius of curvature R1 of the first bent portion 7 is obtained from the bending angle α1 of 7 and the radius of curvature R2 of the second bent portion 9 and the bending angle α2, the first piece 3 and the second piece 5 are also formed at the molding bottom dead center. It is possible to determine the shape of the mold that can be molded by suppressing the springback of the molding member 1 without making the angle θ0 formed by the negative angle less than 90°.

Further, in the above description, the molding member 1 to be molded is curved over the entire longitudinal direction, but in the mold shape determining method according to the present invention, a part of the molding member 1 along the longitudinal direction is formed. It may be one that determines the shape of a molding member having a curved portion that curves, or the shape of a mold that molds a linear molding member along the longitudinal direction.
However, in the case of targeting a molded member having a curved portion that curves along the longitudinal direction, it is preferable that at least one sectional shape be set in the curved portion for the plurality of sectional shapes set in the sectional shape setting step P1. By appropriately adjusting the number of cross-sectional shapes set according to the curvature of the bending in the bending portion, it is possible to accurately determine the shape of the mold that can prevent the springback of the molding member.

Furthermore, in the above description, the bending angle of the bending of the molding member 1 (the angle θ0 formed by the first piece 3 and the second piece 5) is constant along the longitudinal direction, that is, a plurality of angles are set along the longitudinal direction. Although the cross-sectional shapes Sa, Sb and Sc have the same shape, the mold shape determining method according to the present embodiment can be applied even when the bending angle of bending is not constant over the longitudinal direction. Is. In this case, in the cross-sectional shape setting step P1, it is preferable to set the cross-sectional shape at least at both end positions in the direction along the ridge line L of the portion where the bending angle changes, and the bending angle is minimized in the portion where the bending angle changes. If it has an extreme value that is/or has a maximum value, it is desirable to further set the cross-sectional shape at a position that has the extreme value. By setting the cross-sectional shape in this way, each cross-sectional shape can be interpolated so that the bending angle in each cross-sectional shape changes smoothly.

In the above description, as shown in FIG. 2, the molding member 1 including the first piece portion 3 and the second piece portion 5 having a substantially L-shaped cross section has been taken as an example, but the present invention is not limited to this. The target forming member is not limited to this. For example, a forming member having a hat-shaped cross section or a U-shaped cross section may be a metal member that is bent into a mountain shape and has a substantially L-shaped cross section. However, it may be a molded member having a substantially L-shaped cross section locally in the longitudinal direction.

Also in a molding member having a substantially L-shaped cross section locally in the longitudinal direction, a first bent portion that bends in the same direction as the bending and a first bent portion with respect to a portion having the substantially L-shaped cross section. By determining the shape of the mold that locally forms the second bent portions that bend in the opposite direction, local springback can also be appropriately suppressed.

In addition, the mold shape determining method according to the present invention can be performed even when the molding member 1 (FIG. 2) or the molding member 11 (FIG. 3) is molded by either foam molding or draw molding. It is possible to determine the shape of the mold that can appropriately suppress the springback of the molding member 11 after the mold is released.

1 Molded member 3 1st piece part 5 2nd piece part 7 1st bending part 7a, 7b, 7c 1st bending part in each cross-sectional shape 9 2nd bending part 9a, 9b, 9c 2nd bending part in each cross-sectional shape 11 Forming member 13 First piece part 15 Second piece part 17 First bending part 19 Second bending part 21 Mold 23 Die 25 Punch 31 Metal base plate 33 Bending part 41 Forming member 43 First piece part 45 Second piece part 47 Bent portion Ca, Cb, Cc cross section L ridge line Sa, Sb, Sc cross section shape

Claims (6)

The angle between the first piece portion and the second piece portion is formed by bending the metal base plate into a mountain shape and forming a molding member having a first piece portion and a second piece portion and having a substantially L-shaped cross section. A mold shape determining method for determining the shape of a mold to be molded so as to have a target angle,
A cross-sectional shape setting step of setting a cross-section that intersects the ridgeline at a plurality of positions along the ridgeline of the mountain shape of the molding member, and setting a cross-sectional shape at the molding bottom dead center of the molding member for each set cross section. ,
A molding bottom dead center shape determining step of interpolating the set plurality of cross-sectional shapes along the ridge line and determining the shape of the molding member at the molding bottom dead center;
A mold shape determining step of determining the shape of the mold based on the shape of the determined molding member at the bottom dead center.
The cross-sectional shape setting step is continuous from the first piece portion, and is continuous from the first bent portion and a first bent portion that has a curvature substantially equal to that of the substantially L-shaped bend and a bending angle larger than that of the bend, A second bent portion that bends in the opposite direction to the first bent portion and is connected to the second piece portion is set to each of the cross-sectional shapes, and the bending angle of the first bent portion due to springback after release from the mold is set. In order to cancel out the change Δγ1 and the change Δγ2 of the bending angle of the second bent portion, the curvature radius R1 of the first bent portion at the bottom dead center of molding should be obtained according to the procedure of the following steps S1 to S9. A characteristic mold shape determination method.
(S1) Based on the plate thickness and stress-strain relationship of the metal base plate, the radius of curvature R of the bent portion at the forming bottom dead center formed by bending the metal base plate and the bending angle of the bent portion at the forming bottom dead center. The relationship between α and the angle ratio β/α of the bending angle β of the bent portion after release is acquired.
(S3) The bending angle α1 of the first bent portion at the bottom dead center of molding, the radius of curvature R2 and the bending angle α2 of the second bent portion at the bottom dead center of molding are given.
(S5) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α obtained in (S1), the radius of curvature R2 and the bending angle α2 of the second bent portion at the bottom dead center of the molding are used to separate from each other. The bending angle β2 of the second bent portion after the mold is obtained.
(S7) Using the bending angle α2 of the second bent portion at the molding bottom dead center and the bending angle β2 after releasing the mold, and the bending angle α1 of the first bent portion at the molding bottom dead center, The change in the bending angle Δγ1 (=α1−β1) of the first bent portion due to the spring back and the change Δγ2 (=α2−β2) of the bending angle of the second bent portion are equalized and offset. The bending angle β1 of the first bent portion after the mold is calculated.
(S9) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α obtained in (S1), the bending angle α1 of the first bent portion at the bottom dead center of molding and the first angle after releasing the mold The radius of curvature R1 of the first bent portion at the molding bottom dead center is determined from the angle ratio β1/α1 with the bending angle β1 of the first bent portion. The angle between the first piece portion and the second piece portion is formed by bending the metal base plate into a mountain shape and forming a molding member having a first piece portion and a second piece portion and having a substantially L-shaped cross section. A mold shape determining method for determining the shape of a mold to be molded so as to have a target angle,
A cross-sectional shape setting step of setting a cross-section that intersects the ridgeline at a plurality of positions along the ridgeline of the mountain shape of the molding member, and setting a cross-sectional shape at the molding bottom dead center of the molding member for each set cross section. ,
A molding bottom dead center shape determining step of interpolating the set plurality of cross-sectional shapes along the ridge line and determining the shape of the molding member at the molding bottom dead center;
A mold shape determining step of determining the shape of the mold based on the shape of the determined molding member at the bottom dead center.
The cross-sectional shape setting step is continuous from the second piece portion, and is continuous from the first bent portion and a first bent portion that has a curvature substantially equal to that of the substantially L-shaped bend and a bending angle larger than that of the bend, A second bent portion that is bent in a direction opposite to the first bent portion and is connected to the first piece portion is set to each of the cross-sectional shapes, and a bending angle of the first bent portion due to springback after release is set. In order to cancel out the change Δγ1 and the change Δγ2 of the bending angle of the second bent portion, the curvature radius R1 of the first bent portion at the bottom dead center of molding should be obtained according to the procedure of the following steps S1 to S9. A characteristic mold shape determination method.
(S1) Based on the plate thickness and stress-strain relationship of the metal base plate, the radius of curvature R of the bent portion at the forming bottom dead center formed by bending the metal base plate and the bending angle of the bent portion at the forming bottom dead center. The relationship between α and the angle ratio β/α of the bending angle β of the bent portion after release is acquired.
(S3) The bending angle α1 of the first bent portion at the bottom dead center of molding, the radius of curvature R2 and the bending angle α2 of the second bent portion at the bottom dead center of molding are given.
(S5) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α obtained in (S1), the radius of curvature R2 and the bending angle α2 of the second bent portion at the bottom dead center of the molding are used to separate from each other. The bending angle β2 of the second bent portion after the mold is obtained.
(S7) Using the bending angle α2 of the second bent portion at the molding bottom dead center and the bending angle β2 after releasing the mold, and the bending angle α1 of the first bent portion at the molding bottom dead center, The change in the bending angle Δγ1 (=α1−β1) of the first bent portion due to the spring back and the change Δγ2 (=α2−β2) of the bending angle of the second bent portion are equalized and offset. The bending angle β1 of the first bent portion after the mold is calculated.
(S9) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α obtained in (S1), the bending angle α1 of the first bent portion at the bottom dead center of molding and the first angle after releasing the mold The radius of curvature R1 of the first bent portion at the molding bottom dead center is determined from the angle ratio β1/α1 with the bending angle β1 of the first bent portion. The angle between the first piece portion and the second piece portion is formed by bending the metal base plate into a mountain shape and forming a molding member having a first piece portion and a second piece portion and having a substantially L-shaped cross section. A mold shape determining method for determining the shape of a mold to be molded so as to have a target angle,
A cross-sectional shape setting step of setting a cross-section that intersects the ridgeline at a plurality of positions along the ridgeline of the mountain shape of the molding member, and setting a cross-sectional shape at the molding bottom dead center of the molding member for each set cross section. ,
A molding bottom dead center shape determining step of interpolating the set plurality of cross-sectional shapes along the ridge line and determining the shape of the molding member at the molding bottom dead center;
A mold shape determining step of determining the shape of the mold based on the shape of the determined molding member at the bottom dead center.
The cross-sectional shape setting step is continuous from the first piece portion, and is continuous from the first bent portion and a first bent portion that has a curvature substantially equal to that of the substantially L-shaped bend and a bending angle larger than that of the bend, A second bent portion that bends in the opposite direction to the first bent portion and is connected to the second piece portion is set to each of the cross-sectional shapes, and the bending angle of the first bent portion due to springback after release from the mold is set. In order to cancel the change Δγ1 and the change Δγ2 of the bending angle of the second bent portion, the curvature radius R2 of the second bent portion at the molding bottom dead center is set according to the following steps S1 and S13 to S19. A method for determining the shape of a die, which is characterized by obtaining.
(S1) Based on the plate thickness and stress-strain relationship of the metal base plate, the radius of curvature R of the bent portion at the forming bottom dead center formed by bending the metal base plate and the bending angle of the bent portion at the forming bottom dead center. The relationship between α and the angle ratio β/α of the bending angle β of the bent portion after release is acquired.
(S13) The radius of curvature R1 and the bending angle α1 of the first bent portion at the bottom dead center of molding and the bending angle α2 of the second bent portion at the bottom dead center of molding are given.
(S15) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α acquired in (S1), the radius of curvature R1 and the bending angle α1 of the first bent portion at the bottom dead center of the molding are used to separate from each other. The bending angle β1 of the first bent portion after the mold is obtained.
(S17) Using the bending angle α1 of the first bent portion at the molding bottom dead center and the bending angle β1 after the mold release, and the bending angle α2 of the second bent portion at the molding bottom dead center, The change in the bending angle Δγ1 (=α1−β1) of the first bent portion due to the spring back and the change Δγ2 (=α2−β2) of the bending angle of the second bent portion are equalized and offset. The bending angle β2 of the second bent portion after the mold is calculated.
(S19) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α obtained in (S1), the bending angle α2 of the second bent portion at the bottom dead center of the molding and the second angle after mold release The radius of curvature R2 of the second bent portion at the bottom dead center of molding is determined from the angle ratio β2/α2 of the bending angle β2 of the two bent portions. The angle between the first piece portion and the second piece portion is formed by bending the metal base plate into a mountain shape and forming a molding member having a first piece portion and a second piece portion and having a substantially L-shaped cross section. A mold shape determining method for determining the shape of a mold to be molded so as to have a target angle,
A cross-sectional shape setting step of setting a cross-section that intersects the ridgeline at a plurality of positions along the ridgeline of the mountain shape of the molding member, and setting a cross-sectional shape at the molding bottom dead center of the molding member for each set cross section. ,
A molding bottom dead center shape determining step of interpolating the set plurality of cross-sectional shapes along the ridge line and determining the shape of the molding member at the molding bottom dead center;
A mold shape determining step of determining the shape of the mold based on the shape of the determined molding member at the bottom dead center.
The cross-sectional shape setting step is continuous from the second piece portion, and is continuous from the first bent portion and a first bent portion that has a curvature substantially equal to that of the substantially L-shaped bend and a bending angle larger than that of the bend, A second bent portion that is bent in a direction opposite to the first bent portion and is connected to the first piece portion is set to each of the cross-sectional shapes, and a bending angle of the first bent portion due to springback after release is set. In order to cancel the change Δγ1 and the change Δγ2 of the bending angle of the second bent portion, the curvature radius R2 of the second bent portion at the molding bottom dead center is set according to the following steps S1 and S13 to S19. A method for determining the shape of a die, which is characterized by obtaining.
(S1) Based on the plate thickness and stress-strain relationship of the metal base plate, the radius of curvature R of the bent portion at the forming bottom dead center formed by bending the metal base plate and the bending angle of the bent portion at the forming bottom dead center. The relationship between α and the angle ratio β/α of the bending angle β of the bent portion after release is acquired.
(S13) The radius of curvature R1 and the bending angle α1 of the first bent portion at the bottom dead center of molding and the bending angle α2 of the second bent portion at the bottom dead center of molding are given.
(S15) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α acquired in (S1), the radius of curvature R1 and the bending angle α1 of the first bent portion at the bottom dead center of the molding are used to separate from each other. The bending angle β1 of the first bent portion after the mold is obtained.
(S17) Using the bending angle α1 of the first bent portion at the molding bottom dead center and the bending angle β1 after the mold release, and the bending angle α2 of the second bent portion at the molding bottom dead center, The change in the bending angle Δγ1 (=α1−β1) of the first bent portion due to the spring back and the change Δγ2 (=α2−β2) of the bending angle of the second bent portion are equalized and offset. The bending angle β2 of the second bent portion after the mold is calculated.
(S19) Using the relationship between the radius of curvature R of the bent portion and the angle ratio β/α obtained in (S1), the bending angle α2 of the second bent portion at the bottom dead center of the molding and the second angle after mold release The radius of curvature R2 of the second bent portion at the bottom dead center of molding is determined from the angle ratio β2/α2 of the bending angle β2 of the two bent portions. The molding member has a curved portion that curves along the longitudinal direction, and the cross-sectional shape setting step sets at least one cross-sectional shape in the curved portion. The method for determining the shape of a mold according to item 1. The forming member has a portion in which the bending angle of the substantially L-shaped bending changes along the ridgeline of the mountain shape, and the cross-sectional shape setting step includes at least the ridgeline of the portion in which the bending angle changes. A cross-sectional shape is set at both end positions in the direction along, and when the bending angle has an extreme value at a portion where the bending angle changes, the cross-sectional shape at the extreme value position is further set. The mold shape determining method according to any one of claims 1 to 5.

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