JP4007184B2 - Hydraulic molding method and hydraulic molding apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic forming method and a hydraulic forming apparatus.
[0002]
[Prior art]
In conventional hydraulic forming to obtain a molded product from a metal plate material, the metal plate material is positioned facing each other, the periphery of the metal plate material is welded, and the hydraulic pressure is injected into the inside of the metal plate material. (For example, refer to Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 10-85944
[Problems to be solved by the invention]
However, when the target molded product has a curved portion, there is a possibility that molding defects (wrinkles) may occur. For example, the inner circumference of the curved portion is shorter than the outer circumference. Therefore, during the hydraulic forming, the metal plate material corresponding to the inside of the curved portion may cause a surplus of material and may cause a molding failure.
[0005]
In particular, when the part where the molding defect has occurred has a locally long shape, there is a problem that the strength decreases due to stress concentration. On the other hand, when the strength is ensured by increasing the thickness of the metal plate, the cost increases.
[0006]
The present invention has been made in order to solve the problems associated with the prior art described above, and provides a hydraulic molding method and a hydraulic molding apparatus that can suppress the occurrence of molding defects and obtain a stable molded product shape. The purpose is to provide.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 for achieving the above object is a hydraulic forming method for obtaining a molded product having a curved portion from at least two plate materials,
A first mold having a molding surface curved outward and corresponding to a curved surface curved inward in the curved portion of the molded article; and an opening formed in the molding surface;
The plate material is clamped by the second molding die having a molding surface curved inward, corresponding to the curved surface curved outward in the curved portion of the molded product,
The movable mold part, which is disposed so as to be able to advance forward from the opening, is advanced and curved inward of the plate material in contact with the movable mold part by the hydraulic pressure supplied in the initial stage of hydraulic forming. After forming a convex part on the curved surface, the movable mold part is retracted.
[0008]
The invention according to claim 8 for achieving the above object is a hydraulic forming apparatus for obtaining a molded product having a curved portion from at least two plate materials,
A first mold having a molding surface curved outward and corresponding to a curved surface curved inward in the curved portion of the molded article; and an opening formed in the molding surface;
A movable mold part which is disposed so as to be able to move forward outward from the opening;
A second molding die having a molding surface curved inward, corresponding to a curved surface curved outward in the curved portion of the molded article, in cooperation with the first molding die, and clamping and molding a plate material; ,
After the movable mold part is moved forward and a convex portion is formed on the curved surface curved inward of the plate material in contact with the movable mold part by the hydraulic pressure supplied in the initial stage of the hydraulic molding And a hydraulic pressure forming apparatus having drive means for retracting the movable mold part.
[0009]
【The invention's effect】
The present invention configured as described above has the following effects.
[0010]
According to the first aspect of the present invention, the convex portion is formed on the curved surface curved inward of the plate member in contact with the moving movable mold part by the hydraulic pressure supplied in the initial stage of the hydraulic molding. Is done. Therefore, the circumference difference between the curved surface curved inward and the curved surface curved outward is reduced or eliminated, and the occurrence of molding defects (wrinkles) is suppressed. Further, even when molding defects occur, the occurrence of molding defects can be prevented because the portions where excess material is generated are dispersed by the convex portions.
[0011]
Furthermore, after the convex part is formed, the convex part is flattened as the hydraulic pressure rises by retracting the movable mold part, and the convex part disappears.
[0012]
Therefore, it is possible to provide a hydraulic molding method capable of suppressing the occurrence of molding defects and obtaining a stable molded product shape.
[0013]
According to the eighth aspect of the present invention, the liquid pressure supplied in the initial stage of the hydraulic forming is convex to the curved surface curved inward of the plate member in contact with the movable mold part advanced by the driving means. The part can be formed. Therefore, the circumference difference between the curved surface curved inward and the curved surface curved outward is reduced or eliminated, and the occurrence of molding defects is suppressed. Further, even when molding defects occur, the occurrence of molding defects can be prevented because the portions where excess material is generated are dispersed by the convex portions.
[0014]
Furthermore, since the movable mold part can be moved backward by the driving means after the convex portion is formed, it is possible to flatten the convex portion and eliminate the convex portion as the hydraulic pressure increases. It is.
[0015]
Therefore, it is possible to provide a hydraulic molding apparatus that can suppress the occurrence of molding defects and obtain a stable molded product shape.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
FIG. 1 is a perspective view for explaining a plate material according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view for explaining an example of a molded product having a curved portion obtained from the plate material of FIG.
[0018]
The molded article having a curved portion according to the embodiment of the present invention is, for example, an ASKUL part, a side member part, or a body side part, and is applied to provide an automobile part that achieves both weight reduction and high rigidity. Is done. The molded article is composed of at least two plate members 10 and 20, and has a curved surface 11 curved inward and a curved surface 21 curved outward, and the inner circumference is shorter than the outer circumference.
[0019]
The plate members 10 and 20 are made of, for example, an aluminum alloy or stainless steel, and the edges are joined to each other by being welded over substantially the entire circumference or partially. Examples of the welding method include seam welding, arc welding, and laser welding.
[0020]
Moreover, the board | plate material 10 which forms the curved surface 11 curved to the inside has the extension part 12 used as surplus at both ends. The plate member 20 forming the curved surface 21 curved outward is formed with a through hole 22 for supplying hydraulic pressure at one end. In addition, the code | symbol 100 is a welding part.
[0021]
FIG. 3 is a cross-sectional view for explaining the hydraulic forming apparatus according to the embodiment of the present invention. The hydraulic molding apparatus includes an upper mold (first molding mold) 30, a pad 51, a lower mold (second molding mold) 40, a pad driving unit, a punch 60, and a hydraulic pressure supply unit. The plate member 10 having the extension 12 is disposed facing the upper mold 30, and the plate member 20 in which the through hole 22 is formed is disposed facing the lower mold 40.
[0022]
The upper mold 30 can be moved close to and away from the lower mold 40, and has a molding surface 31 that is curved outward, an opening 32, and a recess 33. The molding surface 31 corresponds to the curved surface 11 curved inward in the curved portion of the molded product. The openings 32 are formed on both sides of the center portion of the molding surface 31. The recess 33 is used to form a gate for supplying hydraulic pressure between the joined plate members 10 and 20.
[0023]
The pad 51 is a movable mold part disposed inside the opening 32, and can advance forward from the opening 32 of the upper mold 30. The front end of the pad 51 has a flat end surface having a substantially right-angled edge.
[0024]
The lower die 40 has a molding surface 41 that is curved inward, and is used to cooperate with the upper die 30 and mold the plate members 10 and 20 by clamping. The molding surface 41 corresponds to the curved surface 21 curved outward in the curved portion of the molded product.
[0025]
The pad drive means includes a hydraulic cylinder (reciprocating motion means) 52 for driving the pad 51 and tubes 53 and 54 for supplying hydraulic pressure to the hydraulic cylinder 52. The pad driving means moves the pad 51 forward, and a convex portion is formed on the curved surface curved inside the plate member 10 in contact with the pad 51 by the hydraulic pressure supplied in the initial stage of hydraulic forming. Thereafter, the pad 51 can be retracted.
[0026]
Therefore, the formation of the convex portion reduces or eliminates the circumferential length difference between the curved surface curved inward and the curved surface curved outward, thereby suppressing the occurrence of molding defects (wrinkles). Further, even when molding defects occur, the occurrence of molding defects can be prevented because the portions where excess material is generated are dispersed by the convex portions.
[0027]
Furthermore, since the pad 51 can be retracted by the driving means after the convex portion is formed, it is possible to flatten the convex portion and eliminate the convex portion as the hydraulic pressure increases. That is, generation | occurrence | production of a shaping | molding malfunction can be suppressed and a stable molded product shape can be obtained.
[0028]
Moreover, since the opening part 32 by which the pad 51 is arrange | positioned freely is formed in the both sides which pinched | interposed the center part of the molding surface 31, generation | occurrence | production or growth of a shaping | molding malfunction can be suppressed reliably.
[0029]
In order to reduce or eliminate the trace of the pad 51 that may remain in the molded product (for example, the trace of the edge of the front end), the convex portion is gradually molded using the supplied hydraulic pressure. It is desirable. The pad driving means preferably has a sensor (not shown) for detecting the hydraulic pressure. In this case, the pad 51 can be gradually retreated as the hydraulic pressure increases, and the retreat of the pad 51 and the flattening of the convex portion proceed smoothly. Therefore, the trace of the pad 51 or the trace of the convex portion 13 that may remain in the molded product can be further reduced or eliminated.
[0030]
The punch (tension applying means) 60 is a male part for flanging the extension part 12 of the plate material 10 and is provided in the upper mold 30 by bending the extension part 12 of the plate material 10 at the time of clamping. It is used to generate tension on the plate members 10 and 20. As a result, secondary wrinkles and necking can be prevented.
[0031]
The tension applying means is not limited to the punch 60 as long as the tension can be applied to the plate members 10 and 20 during the hydraulic forming. An extension for generating tension can be provided on the plate 20. In this case, the punch is provided in the lower mold 40.
[0032]
The hydraulic pressure supply means has a hydraulic pressure inlet 71 connected to a piping line from an external hydraulic pressure generator (not shown), and a nozzle portion 72 communicating with the hydraulic pressure inlet 71. The tip of the nozzle portion 72 is formed with a hydraulic pressure inlet and has a cross-sectional shape substantially equal to the inner diameter size of the through hole 22 of the plate member 20. The fluid for supplying the hydraulic pressure is, for example, water.
[0033]
The tip portion of the nozzle portion 72 advances through the through hole 22 of the plate material 20 during mold clamping, and supplies the hydraulic pressure by pressing the plate material 10 against the concave portion 33 of the upper die 30 to be deformed. Form the gate. Accordingly, no gap is generated between the tip of the nozzle portion 72 and the plate member 20, so that leakage of fluid injected between the plate members 10 and 20 from the hydraulic pressure inlet of the nozzle portion 72 can be prevented.
[0034]
As described above, in the present embodiment, it is possible to provide a hydraulic molding device that can suppress the occurrence of molding defects and obtain a stable molded product shape.
[0035]
Next, the hydraulic forming method according to the embodiment of the present invention will be described. 4 is a cross-sectional view for explaining a set of plate materials, FIG. 5 is a cross-sectional view for explaining the start of mold clamping, following FIG. 4, and FIG. 6 is a flanging and mold clamping following FIG. FIG. 7 is a cross-sectional view for explaining the initial stage of hydraulic forming following FIG. 6, and FIG. 8 is for explaining the completion of hydraulic forming following FIG. 7. FIG.
[0036]
First, as shown in FIG. 4, for example, the plate members 10 and 20 whose edges are welded over the entire circumference or partially and joined together are set between the upper mold 30 and the lower mold 40. Is done. The plate members 10 and 20 are preformed as necessary.
[0037]
The plate members 10 and 20 are arranged so that the tip of the nozzle portion 72 is positioned in the through hole 22 of the plate member 20. Further, the pad 51 is advanced outward from the opening 32 of the upper mold 30 by driving the hydraulic cylinder 52 of the pad driving means.
[0038]
Next, as shown in FIG. 5, mold clamping is started by lowering the upper mold 30 (relatively approaching the upper mold 30 and the lower mold 40). The plate members 10 and 20 are deformed by coming into contact with the pad 51 that is advanced outward from the opening 32 of the upper mold 30. Further, the extension portion 12 of the plate member 10 contacts the front end of the punch 60.
[0039]
Then, as shown in FIG. 6, when the upper die 30 is further lowered, the flanging and clamping are completed, and the plate members 10 and 20 are restrained. More specifically, the punch 60 causes the plate members 10 and 20 to be tensioned by bending the extension 12 of the plate member 10.
[0040]
Further, the tip of the nozzle portion 72 of the hydraulic pressure supply means advances through the through hole 22 of the plate material 20 and supplies the hydraulic pressure by pressing the plate material 10 against the concave portion 33 of the upper mold 30 to be deformed. A gate is formed for the purpose. Accordingly, no gap is generated between the tip of the nozzle portion 72 and the plate member 20.
[0041]
Next, as shown in FIG. 7, the fluid supplied from the external hydraulic pressure generator is supplied from the hydraulic pressure inlet formed at the tip of the nozzle portion 72 to the plate members 10 and 20 via the gate. Inject in between. At this time, since no gap is generated between the tip of the nozzle portion 72 and the plate member 20, fluid leakage is prevented.
[0042]
As the hydraulic pressure in the space formed between the plate members 10 and 20 rises, the convex portion 13 is gradually formed on the curved surface 11 that is curved inside the plate member 10 that is in contact with the pad 51. The Therefore, the formation of the convex portion reduces or eliminates the circumferential length difference between the curved surface curved inward and the curved surface curved outward, thereby suppressing the occurrence of molding defects. The hydraulic pressure P ₁ supplied at the initial stage of the hydraulic forming (when the convex portion is formed) is, for example, 20 MPa (200 bar).
[0043]
In addition, since the opening part 32 where the pad 51 is arrange | positioned freely is formed in the both sides which pinched | interposed the center part of the shaping | molding surface 31, generation | occurrence | production or growth of a shaping | molding fault is suppressed reliably. Further, since the convex portion is gradually formed, the trace of the pad 51 that may remain in the molded product is reduced or eliminated.
[0044]
Thereafter, the pad 51 is gradually retracted as the hydraulic pressure in the space formed between the plate members 10 and 20 further increases. As a result, the convex portion is flattened and the convex portion disappears. At this time, even if a molding defect occurs, the occurrence of molding defects is prevented because the portions where the material surplus is generated are dispersed by the convex portions.
[0045]
In addition, since the tension | tensile_strength is added to the board | plate materials 10 and 20 by the extension part 12 of the bent board | plate material 10, secondary wrinkles and necking are prevented. Further, since the pad 51 is gradually retracted as the hydraulic pressure increases, the retreat of the pad 51 and the flattening of the convex portion proceed smoothly. Therefore, the trace of the pad 51 or the trace of the convex portion 13 that may remain in the molded product is reduced or eliminated.
[0046]
Then, the hydraulic pressure in the space formed between the plate members 10 and 20 reaches the final pressure, and the inner surface shape of the molding surface 31 of the upper mold 30 and the molding surface 41 of the lower mold 40 as shown in FIG. The plate members 10 and 20 are formed in an outer surface shape that matches the above. The final hydraulic pressure P ₂ supplied at the completion of the hydraulic forming is, for example, 100 MPa (1000 bar).
[0047]
Next, after the supply of the hydraulic pressure is stopped and the pressure is released, the upper mold 30 is raised (the upper mold 30 and the lower mold 40 are relatively separated) to open the mold. Then, the molded product is taken out and, if necessary, a final product is obtained by performing trimming such as cutting of the extended portion 12 of the bent plate member 10.
[0048]
As described above, in the present embodiment, it is possible to provide a hydraulic molding method capable of suppressing the occurrence of molding defects and obtaining a stable molded product shape.
[0049]
The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims.
[0050]
For example, the front end of the pad is not limited to one having a flat end surface having a substantially right-angled edge, but has a front end having a curved edge as shown in FIG. As shown in FIG. 10, the pad 51 </ b> A or a pad 51 </ b> B having a front end having an end surface on which wavy irregularities are formed can be applied. In these cases, since the flow of the material constituting the convex portion proceeds smoothly, it is possible to further reduce or eliminate the trace of the pad or the convex portion that may remain in the molded product. .
[Brief description of the drawings]
FIG. 1 is a perspective view for explaining a plate material according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view for explaining an example of a molded product having a curved portion obtained from the plate material of FIG.
FIG. 3 is a cross-sectional view for explaining a hydraulic forming apparatus according to an embodiment of the present invention.
FIG. 4 is a cross-sectional view for explaining a set of plate members in the hydraulic forming method according to the embodiment of the present invention.
FIG. 5 is a cross-sectional view for explaining the start of mold clamping, continued from FIG. 4;
6 is a cross-sectional view for explaining the completion of flanging and mold clamping, following FIG. 5;
FIG. 7 is a cross-sectional view for explaining the initial stage of hydraulic forming following FIG. 6;
FIG. 8 is a cross-sectional view for explaining the completion of hydraulic forming following FIG. 7;
FIG. 9 is a cross-sectional view for explaining a modification of the pad in the hydraulic forming apparatus according to the embodiment of the present invention.
FIG. 10 is a cross-sectional view for explaining another modified example of the pad in the hydraulic forming apparatus according to the embodiment of the present invention.
[Explanation of symbols]
10 ... board material,
11 ... curved surface,
12 ... Extension part,
13 ... convex part,
20 ... board material,
21 ... curved surface,
22 ... through hole,
30 ... Upper mold (first mold),
31 ... molding surface,
32 ... opening,
33 ... concave,
40 ... Lower mold (second mold),
41 ... molding surface,
51, 51A, 51B ... pads (movable mold parts),
52 ... Hydraulic cylinder,
53, 54 ... Tube,
60 ... Punch (male part),
71 ... hydraulic inlet,
72 ... Nozzle part,
100 ... welded part,
P ₁ ... Initial hydraulic pressure,
P ₂ ... Final hydraulic pressure.

Claims (14)

A hydraulic forming method for obtaining a molded product having a curved portion from at least two plate materials,
A first mold having a molding surface curved outward and corresponding to a curved surface curved inward in the curved portion of the molded article; and an opening formed in the molding surface;
The plate material is clamped by the second molding die having a molding surface curved inward, corresponding to the curved surface curved outward in the curved portion of the molded product,
The movable mold part, which is disposed so as to be able to advance forward from the opening, is advanced and curved inward of the plate material in contact with the movable mold part by the hydraulic pressure supplied in the initial stage of hydraulic forming. A hydraulic forming method, comprising: forming a convex portion on a curved surface, and then retracting the movable mold part. The hydraulic forming method according to claim 1, wherein the opening is formed on both sides sandwiching a central portion of the forming surface. The hydraulic molding method according to claim 1 or 2, wherein the retraction of the movable mold part is gradually executed as the hydraulic pressure increases. The hydraulic molding method according to claim 1, wherein a front end of the movable mold part has a curved edge. The hydraulic forming method according to any one of claims 1 to 4, wherein the front end of the movable mold part has an end face on which wavy irregularities are formed. The hydraulic forming method according to any one of claims 1 to 5, wherein tension is applied to the plate material during the hydraulic forming. The hydraulic pressure according to claim 6, wherein at least one of the plate members has extension portions at both ends, and the tension is generated by bending the extension portions at the time of clamping. Molding method. A hydraulic forming apparatus for obtaining a molded product having a curved portion from at least two plate materials,
A first mold having a molding surface curved outward and corresponding to a curved surface curved inward in the curved portion of the molded article; and an opening formed in the molding surface;
A movable mold part which is disposed so as to be able to move forward outward from the opening;
A second molding die having a molding surface curved inward, corresponding to a curved surface curved outward in the curved portion of the molded article, in cooperation with the first molding die, and clamping and molding a plate material; ,
After the movable mold part is moved forward and a convex portion is formed on the curved surface curved inward of the plate material in contact with the movable mold part by the hydraulic pressure supplied in the initial stage of the hydraulic molding And a drive means for moving the movable mold part backward. The hydraulic forming apparatus according to claim 8, wherein the openings are formed on both sides sandwiching a central portion of the molding surface. The hydraulic molding apparatus according to claim 8 or 9, wherein the retraction of the movable mold part is gradually executed as the hydraulic pressure increases. The hydraulic forming apparatus according to any one of claims 8 to 10, wherein a front end of the movable mold part has a curved edge. The hydraulic forming apparatus according to any one of claims 8 to 11, wherein a front end of the movable mold part has an end face on which wavy irregularities are formed. The hydraulic forming apparatus according to any one of claims 8 to 12, further comprising tension applying means for applying tension to the plate material during the hydraulic forming. At least one of the plate members has an extension part at both ends, and has a male part for generating the tension by bending the extension part at the time of clamping. Item 14. The hydraulic forming apparatus according to Item 13.

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