JP4281463B2 - Hydraulic molding method and hydraulic molding apparatus - Google Patents

Description

  The present invention relates to a hydraulic forming method and a hydraulic forming apparatus.

In conventional hydraulic forming, a preform formed by welding and joining the periphery of a plurality of stacked metal plate materials is placed inside a vertically divided mold and clamped. Then, a liquid is supplied to the inside of the preformed body so as to bulge, and is pressed into a cavity of a mold to be molded into a product shape (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 9-168827

  However, the following problems arise in the conventional hydraulic forming as described above.

Problem 1
Since the periphery of the metal plate material is welded to form a preform, a welding process is required before hydraulic forming, which increases the number of work steps.

Problem 2
The edge of the preform pressed by the mold moves toward the mold cavity at the beginning of molding, causing material inflow. Here, unless the edge of the preformed body that has been welded and joined is smoothed in advance or an extra portion is not removed, it becomes a factor that hinders material inflow. This is because the edge of the preform is held on the holder surface of the mold, but rubs against the holder surface to cause frictional resistance. This limits the material inflow, which is not ideal hydraulic forming.

  The present invention has been made in order to solve the above-described problems of the prior art, and does not require a welding process for welding between plate members, etc., and is capable of improving the material inflow of the preform. It is an object to provide a method and a hydroforming apparatus.

The hydroforming method of the present invention is a hydroforming method for hydroforming a superposed plate material, and as a first pre-formation before injecting the processing liquid between the superposed plate materials, At the same time that the overlapped plate members are clamped by the first forming die and the second forming die for hydraulic forming , the edges of the plate members are joined together by caulking. A plate material provided with a caulking portion is included in the portion, and the caulking portion is bent in advance toward a plate material not provided with the caulking portion before the first pre-forming.

Further, the hydroforming apparatus of the present invention is a hydroforming apparatus that is applied to the stacked plate materials, the cavity corresponding to one surface obtained by dividing the outer shape of the molded product, and the plate material A first mold having a holder part for holding the edge part , and a convex part provided on the holder part, and a cavity corresponding to the other surface obtained by dividing the outer shape of the molded product. And a second mold having a holder part for holding the edge of the overlapped plate material, and one edge of the overlapped plate material is caulked upright on the other plate material side. And the caulking portion is bent to the other plate material side when the first molding die and the second molding die are brought close to the convex portion of the first molding die. An inclined surface is formed .

  According to the hydraulic forming method of the present invention, as the first preforming, the edges of the overlapped plate materials are caulked, so that the edges can be easily joined without welding the edges. Can be sealed. Since it is not necessary to weld the edges, the working time can be shortened. In addition, since the crimped preform is smoother than the preform formed by welding, it is difficult to cause frictional resistance with the holder, and good material inflow can be achieved.

  According to the hydraulic forming apparatus of the present invention, since the edges of the overlapped plate members are caulked as the first preforming, the edges can be easily joined without welding the edges, Can be sealed. Since there is no need for a preliminary process for welding the edge, the working time can be shortened. In addition, since the crimped preform is smoother than the preform formed by welding, it is difficult to cause frictional resistance with the holder, and good material inflow can be achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view for explaining a preform according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view for explaining a molded product according to an embodiment of the present invention.

  In the hydraulic forming, at least two plate members 11 and 12 are used in an overlapping manner. The plate members 11 and 12 are made of, for example, an aluminum alloy or stainless steel. The plate member 12 is bent in advance at an end portion to form a caulking portion 14. The plate material 11 is superimposed on the plate material 12 so as to substantially contact the caulking portion 14 of the plate material 12. At this stage, the plate members 11 and 12 are only overlapped. Accordingly, the plate members 11 and 12 are not joined at the caulking portion 14 and the airtightness is not yet ensured. Hereinafter, a superposition of the two plate members 11 and 12 is referred to as a preformed body 10.

  The molded product 20 obtained by preforming the preformed body 10 according to the present invention and then hydraulically molding is an automotive part such as an axle part, a side member part, or a body side part. In the present embodiment, it is possible to increase the amount of deformation by hydraulic molding and increase the molding height limit.

  That is, the molded product 20 having a molding height H larger than that of the conventional one can be obtained without performing secondary molding or blanket attachment. Therefore, the application range of the molded product 20 is wide.

  Initially, the operation | movement of the prior deformation | transformation of the board | plate materials 11 and 12 by a hydraulic forming apparatus is demonstrated.

  FIG. 3 is a cross-sectional view for explaining the hydraulic forming apparatus according to the embodiment of the present invention, and FIG. 4 is a cross-sectional view for explaining preliminary deformation in the hydraulic forming apparatus of FIG.

  The hydroforming apparatus 30 includes an upper mold (second mold) 40, a lower mold (first mold) 50, and a punch (male member) 60.

  The upper die 40 and the lower die 50 are divided dies, and include cavities 41 and 51 corresponding to the outer shape of the molded product 20, and holder portions 45 and 55 for holding the edge of the preform 10. And can be closely spaced.

  A convex portion 46 is formed on the holder portion 45. The convex part 46 has a surface inclined so that the caulking part 14 bends toward the plate member 11 side. For this reason, when the upper mold 40 and the lower mold 50 are brought close to and away from each other, the caulking portion 14 of the preform 10 is bent toward the plate material 11 (the plate material not provided with the caulking portion) by the convex portion 46. Thereby, it becomes possible to crimp the end portions of the plate members 11 and 12 and join them together in the first preforming described later. The lower mold 50 is provided with a concave portion 56 corresponding to the shape of the convex portion 46 of the upper mold 40.

  The cavity 41 of the upper mold 40 corresponds to one surface obtained by dividing the outer shape of the molded product 20, and the cavity 51 of the lower mold 50 is the other obtained by dividing the outer shape of the molded product 20. Corresponds to

  The cavity 41 of the upper mold 40 has an opening 42. The punch 60 is disposed so as to protrude outward (inside the cavity) from the opening 42. The punch 60 is controlled by, for example, cylinder means (reciprocating motion means) using hydraulic pressure or pneumatic pressure as a drive source.

  The end surface 61 of the punch 60 has a planar shape having a substantially right edge. Therefore, it is possible to prevent the edge of the end surface 61 of the punch 60 that has retracted into the opening 42 from being swelled to cause a flaw in the plate material 11 that comes into contact.

  The punch 60 is used for pre-deformation (second preforming) of the preform 10 placed on the lower mold 50 before the upper mold 40 is clamped. In the second preforming, the punch 60 is protruded to press and deform the portion of the preformed body 10 located in the cavity 51, and the edge (caulking portion 14) of the preformed body 10 located in the holder portion 55. Is partially drawn into the cavity 51.

  In the second preforming, the end portion of the preformed body 10, that is, the caulking portion 14 of the plate material 12 is not sandwiched between the holder portions 45 and 55. The plate members 11 and 12 are still in a state where they are just overlapped. Since the preformed body 10 is not fixed to the holder portions 45 and 55, the frictional resistance between the preformed body 10 and the lower mold 50 is small, and the punch 60 presses more material into the cavity than before. It is possible to arrange in advance.

  For this reason, after mold clamping, at the stage where hydraulic forming proceeds based on the elongation of the material present in the cavity, it is possible to suppress the excessive progress of plate thickness reduction and suppress the occurrence of molding defects such as material breakage. Can do. It is also possible to increase the amount of deformation by hydraulic forming.

  Since the 2nd preforming is given to preforming object 10 arranged for mold clamping, the increase in work man-hours is small and the rise in manufacturing cost is controlled.

  The pre-deformed cross-sectional length of the part of the preform 10 located in the cavity 51 is preferably about 80% or more of the cross-sectional peripheral length of the cavity 51 of the lower mold 50. In this case, excessive elongation of the material can be reliably suppressed during the hydraulic molding.

  The punch 60 is not limited to being disposed inside the upper mold 40, and can be disposed inside the lower mold 50 by providing an opening in the cavity 51 of the lower mold 50. Furthermore, the punch 60 can be configured as a separate body without being disposed in the molds 40 and 50.

  Next, a state of clamping the preform 10 that is a feature of the present invention will be described.

  FIG. 5 is a cross-sectional view for explaining mold clamping.

  The mold clamping is performed after the second preforming is performed by the punch 60 as shown in FIG. In order to clamp the preform 10, the upper mold 40 and the lower mold 50 are brought closer to each other. First, the upper surface of the caulking portion 14 hits the upper mold 40. As described above, the caulking portion 14 is bent a little toward the plate material 11 in advance, and when the upper die 40 and the lower die 50 are further brought closer, as shown in FIG. The plate member 12 is bent so as to cover. Thereby, the plate material 12 will pinch | interpose the plate material 11 by the crimping | crimped part 14 (1st preforming). By firmly caulking the caulking portion 14 with the holder portions 45 and 55 with a force that does not break, the plate materials 11 and 12 are joined, and the airtightness between the plate materials 11 and 12 is ensured.

  Next, an explanation will be given of the action of the caulking portion 14 caulked by the holder portion 45 at the time of hydraulic forming and until the final product is created.

  6 is a cross-sectional view for explaining the start of hydraulic forming, FIG. 7 is a cross-sectional view for explaining an intermediate stage of hydraulic forming, and FIG. 8 is for explaining the end of hydraulic forming. FIG.

  As shown in FIGS. 3 to 5, the plate members 11 and 12 are preformed by the punch 60 and then joined by the caulking portion 14 at the time of mold clamping. Here, the preform 10 is provided with an inlet (not shown) connected to an external hydraulic pressure generator. Liquid is supplied from the hydraulic pressure generator into the preformed body 10, and hydraulic molding is started as shown in FIG. The liquid is, for example, water.

  In the initial stage of molding, the caulking portion 14 of the preformed body 10 moves toward the cavities 41 and 51 of the molds 40 and 50 to cause material inflow. Here, the caulking portion 14 can smooth the material inflow compared to the case where the end portions of the plate members 11 and 12 are joined by welding. The reason is as follows.

  Reason (1) The caulking portion 14 does not have unevenness on the surface like a welded joint. Therefore, the frictional resistance against the holder surfaces 45 and 55 is small.

  Reason (2) The caulking portion 14 mainly contacts the holder surface 45 of the upper mold 40. Therefore, the plate material 11 hardly contacts the holder surface 45, and the contact area is small. If the contact area is small, the frictional resistance is also small.

  In the present invention, since the joining of the plate members 11 and 12 by the caulking portion 14 is employed, the material inflow can be smoothly performed for the reasons (1) and (2).

  As the hydraulic pressure rises, the hydraulic molding proceeds and reaches a stage as shown in FIG. When the hydraulic pressure reaches the final pressure, the preform 10 has an outer surface shape that matches the inner surface shape of the cavities 41 and 51, as shown in FIG. The final hydraulic pressure is a hydraulic pressure at which the corner radius of curvature of the molded product corresponding to the bottom edge portions 43 and 53 of the cavities 41 and 51 is obtained, and is 100 MPa, for example. 7 and 8, the frictional resistance of the caulking portion 14 is small, so that a slight material inflow can occur.

  Further, since the cross-sectional peripheral length of the preform 10 is shorter than the cross-sectional peripheral lengths of the cavities 41 and 51, the concave portion generated in the central portion of the plate 11 as shown in FIG. Stretched. Therefore, wrinkles (remaining material) do not occur at the completion of hydroforming.

  Thereafter, the supply of fluid is stopped and the pressure is released, and the upper die 40 is raised (the upper die 40 and the lower die 50 are relatively separated from each other) to open the die. Then, the molded product (see FIG. 2) is taken out, and a final product is obtained by performing trimming such as cutting of the caulking portion 14 of the preform 10 as necessary.

  As described above, in the hydraulic molding method using the hydraulic molding apparatus 30, the first preforming is performed by caulking the caulking portion 14 by the action of the holder portion 45 of the upper die 40 and the holder portion 55 of the lower die 50. As a result, the ends of the plate members 11 and 12 can be joined. Therefore, it is not necessary to join the end portions of the plate members 11 and 12 in advance by welding or the like, and the man-hours corresponding to that can be reduced. Moreover, since no equipment for welding or the like is required, the equipment cost can be reduced.

  Further, since the preformed body 10 provided with the caulking portion 14 has a small frictional resistance with respect to the holder portions 45 and 55, the material can be easily introduced during the hydraulic forming. Therefore, the deformation due to the extension of the material is small, the excessive progress of the plate thickness reduction can be suppressed, and the occurrence of molding defects such as the material breaking can be suppressed.

  In the above embodiment, the caulking portion 14 is caulked and the plate members 11 and 12 are joined simultaneously with the mold clamping, but the present invention is not limited to this. Before the mold clamping and the second preliminary molding by the punch 60, the upper mold 40 and the lower mold 50 may be once brought close to the same level as that at the time of mold clamping, and the caulking portion 14 may be caulked. Thereafter, the preform 10 can be second preformed by the punch 60. As a result, the plate materials 11 and 12 can be integrally joined to the second pre-formation, so that it is possible to avoid a situation in which the plate materials 11 and 12 are displaced during the second pre-formation and the caulking portion 14 cannot be caulked well during the subsequent mold clamping. . In addition, the second preforming by the punch 60 and the caulking of the caulking portion 14 may occur simultaneously.

  Moreover, in the said embodiment, although only one punch is provided, it is not limited to this. You may perform 2nd preforming using a some punch (male type member). Pre-deformation can be performed efficiently by a plurality of punches.

  Moreover, in the said embodiment, although the convex part 46 is provided in the upper mold | type 40, it is not limited to this. A mold that acts to bend the caulking portion 14 toward the plate member 11 as in the case of the convex portion 46 may be separately prepared. In this case, the caulked portion 14 of the preformed product 10 is inclined toward the plate member 11 by using a separately prepared mold, and is removed from the mold, so that the preliminary mold 10 is provided between the upper mold 40 and the lower mold 50 where the convex portions 46 are not provided. The molded product 10 is arranged. In this way, by realizing the process of inclining the caulking part 14 and the process of caulking the caulking part 14 (first pre-molding) with different molds, the convex part 46 is a holder for the lower mold 50 during mold clamping. It does not get in the way of hitting part 55. The second pre-forming by punching may be performed in the same process as the caulking portion 14 inclination process, or may be performed in the same process as the first pre-forming.

It is sectional drawing for demonstrating the preforming body which concerns on embodiment of this invention. It is sectional drawing for demonstrating the molded article which concerns on embodiment of this invention. It is sectional drawing for demonstrating the hydraulic forming apparatus which concerns on embodiment of this invention. It is sectional drawing for demonstrating the prior deformation | transformation in the hydraulic forming apparatus of FIG. It is sectional drawing for demonstrating the mold clamping in the hydraulic forming apparatus of FIG. It is sectional drawing for demonstrating the time of the start of the hydraulic forming in the hydraulic forming apparatus of FIG. It is sectional drawing for demonstrating the middle stage of the hydraulic forming in the hydraulic forming apparatus of FIG. It is sectional drawing for demonstrating the time of completion | finish of the hydraulic forming in the hydraulic forming apparatus of FIG.

Explanation of symbols

10 ... preformed body,
11, 12 ... board material,
14 ... crimping part,
20 ... molded product,
30 ... Hydraulic molding device,
40 ... Upper mold (second mold),
41, 51 ... cavity,
42 ... opening,
43, 53 ... bottom edge,
44, 54 ... bent portion,
45, 55 ... Holder part,
50 ... Lower mold (first mold),
60 ... Punch (male type member),
61 ... end face,
H: Molding height.

Claims (6)

A hydroforming method for hydroforming the superposed plate materials,
At the same time as the first pre-molding before injecting the processing liquid between the stacked plate materials, the stacked plate materials are clamped by the first and second forming molds for hydraulic forming , The edges of the plate material are joined together by caulking,
The overlapped plate material includes a plate material provided with a caulking portion at an edge,
The hydraulic forming method, wherein the caulking portion is bent in advance toward a plate material not provided with the caulking portion before the first pre-forming. The first preform is
It said first mold having a holder portion for holding cavity, and the edges of the superposed plate corresponding to one of the surfaces obtained by dividing the outer shape of the molded article,
It said second mold having a holder portion for holding the edge of the molded article of the outer shape of the cavity corresponding to the other surface obtained by dividing, and the superimposed sheet,
The hydraulic forming method according to claim 1, wherein the hydraulic forming method is performed by sandwiching the holder portion between the holder portions. Before the processing liquid is injected between the stacked plate materials, as a second preforming, the overlapped plate material portion located in the cavity of the first mold is pressed and deformed by a male member. 3. The hydraulic molding according to claim 2 , further comprising a step of partially pulling an edge portion of the overlapped plate member positioned in the holder portion of the first molding die into the cavity of the first molding die. Method. A hydraulic forming device applied to the stacked plate materials,
The 1st shaping | molding die which has the cavity corresponding to one surface obtained by dividing | segmenting the external shape of a molded article, the holder part for hold | maintaining the edge of the said board | plate material, and the convex part provided in this holder part When,
A second mold having a cavity corresponding to the other surface obtained by dividing the outer shape of the molded product, and a holder portion for holding an edge of the overlapped plate material;
Have
On one edge of the stacked plate material, a caulking portion is formed upright on the other plate material side,
  An inclined surface is formed on the convex portion of the first mold so that the caulking portion is bent toward the other plate member when the first mold and the second mold are brought close to each other. The hydraulic forming device. The holder part of the said 1st shaping | molding die and a 2nd shaping | molding die has a surface which mutually agree | coincides so that the said crimping | crimping part can be integrally joined by crimping simultaneously with the clamping of the said board | substrate piled up. of hydraulic forming apparatus. A male member provided so as to protrude toward the cavity of the first mold;
The male mold member presses and deforms the overlapped plate material portion positioned in the cavity of the first mold before injecting the processing liquid between the overlapped plate materials, 6. The hydraulic forming apparatus according to claim 4, wherein an edge portion of the overlapped plate member located in the holder portion of one mold is partially drawn into the cavity of the first mold . 6.

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