JP2006026648A - Hydraulic forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic forming method for easily obtaining a formed part which is partially reinforced in strength and rigidity and has excellent accuracy. <P>SOLUTION: This method is a hydraulic forming method to which a preform 40 having two superposed metal sheets 10, 20 which are joined in the periphery is applied. After welding a reinforcement 30 on at least one side of the metal sheets 10, 20, the preform 40 is arranged in the inside of forming dies 70, 80, and clamping is performed and the preform 40 is bulged and deformed by adding hydraulic pressure in the inside of it. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydroforming method.

In conventional hydraulic forming, a preform formed by joining the periphery of the stacked plate materials is placed inside the molding die, and after clamping the mold, hydraulic pressure is applied to the inside of the preform. Swelled and deformed to obtain a molded product (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 9-168827

  However, when the reinforcing material is welded and the strength and rigidity of the molded product are partially improved, the portion that has become hot due to the welding heat causes thermal contraction when the temperature decreases. Thermal shrinkage has the problem of generating stress that distorts the molded product and reducing the accuracy of the molded product. Further, the shape is not stable due to the influence of the springback during welding, and there is a possibility that the welding quality may be lowered or a gap may be formed between the reinforcing material and the molded product.

  On the other hand, it is possible to correct the distortion of the molded product by using a mold or the like, but this causes a decrease in productivity and an increase in manufacturing cost.

  The present invention has been made to solve the problems associated with the above-described prior art, and provides a hydraulic forming method for easily obtaining a molded product having partially enhanced strength and rigidity and having good accuracy. The purpose is to do.

To achieve the above object, the present invention provides:
A hydroforming method to which a preformed body having two overlapping plate materials joined at the periphery is applied,
After welding a reinforcing material to at least one of the plate members, the preform is placed inside a molding die and clamped, and hydraulic pressure is applied to the inside of the preform to bulge and deform. A hydraulic forming method characterized by:

  According to the present invention configured as described above, since the reinforcing material is welded to at least one of the plate members of the preform, a molded product in which strength and rigidity are partially reinforced can be obtained. Further, since the distortion of the plate material or the preformed body caused by the heat shrinkage caused by the welding of the reinforcing material is corrected at the time of the bulging deformation of the preformed body, the accuracy of the obtained molded product is not affected. Furthermore, since the reinforcing material is welded in the state of the plate material before forming, spring back does not occur during welding, and deterioration of welding quality and generation of gaps are suppressed. Further, since an independent facility or process for correcting the distortion is not required, the productivity is not lowered and the manufacturing cost is not increased. That is, it is possible to provide a hydraulic forming method for easily obtaining a molded product having strength and rigidity partially reinforced and having good accuracy.

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

  FIG. 1 is a perspective view for explaining a molded product according to an embodiment of the present invention. The molded product 50 according to the present embodiment is a hollow structural material having a flange portion 51 to which the reinforcing material 30 is welded and joined, and the strength and rigidity are partially reinforced. The molded product 50 is applied to, for example, an axle part, a body side part, and a suspension part, and is used to provide an automobile part that achieves both weight reduction and high rigidity. Reference numerals 31 and 52 denote joints.

  2 and 3 are a plan view and a rear view for explaining the preform according to the embodiment of the present invention, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG.

  The preform 40 that is a material of the molded product 50 includes two overlapping plate materials 10 and 20 and a reinforcing material 30. The plate members 10 and 20 and the reinforcing member 30 are made of, for example, a hot rolled steel plate or a cold rolled steel plate.

  The plate member 10 includes a central portion 15 and end portions 11 and 16 located with the central portion 15 interposed therebetween, and a joint portion 41 is disposed in the periphery. The end portion 11 is formed with a dome-shaped portion 12.

  The plate member 20 is similar to the plate member 10, has a central portion 25 that faces the central portion 15 of the plate member 10, and end portions 21 and 26 that face the end portions 11 and 16 of the plate member 10. Is set to a slightly larger size. The end 21 has an opening 22 that is aligned with the dome 12.

  The reinforcing member 30 has a substantially rectangular sheet shape, is joined to the central portion 15 of the plate member 10 by welding, and is located on the outer surface located on the opposite side of the mating surface of the plate members 10 and 20. The reinforcing member 30 is not limited to welding to one of the plate members 10 and 20, and can be welded to both the plate members 10 and 20 in consideration of the intended strength and rigidity. Since the reinforcing material 30 is welded in the state of a plate material before forming, no springback occurs during welding, and deterioration of welding quality and generation of gaps are suppressed.

  In consideration of workability and the influence of welding of the reinforcing material 30, it is preferable to join the periphery of the plate materials 10 and 20 after welding the reinforcing material 30. However, it is also possible to weld the reinforcing member 30 after joining the periphery of the plate members 10 and 20 as necessary.

  The welding method of the reinforcing material 30 is not particularly limited, and it is possible to apply through welding, fillet welding, or resistance welding by plasma arc welding or laser welding. Moreover, it is also possible to use a filler wire suitably. In addition, the joining method of the periphery of the board | plate materials 10 and 20 is not specifically limited, It is possible to apply adhesion | attachment and welding. Further, the welding method of the reinforcing member 30 can be the same.

  FIG. 5 is a cross-sectional view for explaining the hydraulic forming apparatus according to the embodiment of the present invention, FIG. 6 is a plan view for explaining the upper mold of the hydraulic forming apparatus shown in FIG. These are top views for demonstrating the lower mold | type of the hydraulic-molding apparatus shown by FIG.

  The hydraulic molding apparatus 60 according to the embodiment of the present invention includes a molding die (upper mold 70 and lower mold 80) and a hydraulic pressure supply means 90.

  The upper mold 70 and the lower mold 80 are installed so as to be close to and away from each other, and the preformed body 40 is arranged on the inner side and clamped. The upper mold 70 and the lower mold 80 have cavity surfaces 71 and 81 and pressing portions 75 and 85. The cavity surfaces 71 and 81 have a shape corresponding to the outer shape of the target molded product 50. The pressing portions 75 and 85 are portions that grip the outer periphery of the preform 40 by mold clamping.

  The cavity surface 71 of the upper mold 70 includes a side surface portion 72 extending from the boundary of the mold dividing surface, a substantially flat bottom portion 74, and a bent transition portion 73 positioned between the side surface portion 72 and the bottom portion 74. The bottom 74 is located at the center of the cavity surface 71 and faces the reinforcing member 30 welded to the center 15 of the plate 10.

  The pressing portion 75 includes a concave portion 76 extending from the cavity surface 71 and arc-shaped grooves 77 and 78 disposed so as to surround the tip portion 76 </ b> A of the concave portion 76. The distal end portion 76A has a cross-sectional shape corresponding to the outer shape of a portion obtained by dividing the dome-shaped portion 12 of the preform 40 into two in the vertical direction. The center of the arc-shaped grooves 77 and 78 is the center of the distal end portion 76A.

  Similar to the cavity surface 71 of the upper mold 70, the cavity surface 81 of the lower mold 80 has a side surface portion 82 extending from the boundary of the mold dividing surface, a substantially flat bottom portion 84, and a space between the side surface portion 82 and the bottom portion 84. And a bent transition portion 83 located. The pressing portion 85 has a substantially rectangular recess 86 in which the nozzle portion 91 is disposed.

  The hydraulic pressure supply means 90 is used for applying a hydraulic pressure to the inside of the preform 40 and causing it to bulge, and has a flow path 98 and a nozzle portion 91 connected to the hydraulic pressure circuit 99. The flow path 98 extends inside the lower mold 80 and reaches the nozzle portion 91.

  The nozzle portion 91 has a dome-shaped portion 92 corresponding to the inner surface of the dome-shaped portion 12 of the preform 40, and annular convex portions 94, 95 disposed so as to surround the dome-shaped portion 92. The annular convex portions 94 and 95 are aligned with the arc-shaped grooves 77 and 78 of the pressing portion 75 of the upper mold 70. The sizes of the annular convex portions 94 and 95 are smaller than the sizes of the arc-shaped grooves 77 and 78 and are set in consideration of the thickness of the plate members 10 and 20.

  The dome-shaped portion 92 is insertable into the opening 22 of the plate member 20 and has an inlet 93 communicating with the flow path 98. Therefore, when the nozzle portion 91 is inserted into the opening 22 and disposed in the dome-shaped portion 12 of the preform 40, the molding medium supplied from the hydraulic circuit 99 passes through the nozzle portion 91 and the preform. 40 can be introduced inside. A forming medium for applying a liquid pressure to the inside of the preform 40 to swell is, for example, water.

  Next, the hydraulic forming method according to the embodiment of the present invention will be described. 8 is a cross-sectional view for explaining mold clamping, FIG. 9 is a cross-sectional view for explaining the initial stage of molding following FIG. 8, and FIG. 10 is a cross-section for explaining the middle stage of molding following FIG. FIG. 11 and FIG. 11 are cross-sectional views for explaining the latter half of the molding subsequent to FIG.

  First, a preformed body 40 having two overlapping plate materials 10 and 20 joined at the periphery and a reinforcing material 30 welded in advance to the plate material 10 is arranged in the lower mold 80. At this time, the opening 22 formed in the plate member 20 is positioned in the dome-shaped portion 92 of the nozzle portion 91 of the hydraulic pressure supply means 90, and the dome-shaped portion 92 is fitted into the dome-shaped portion 12 of the plate material 10. . Thereby, the injection port 93 of the dome-shaped portion 92 is aligned between the plate material 10 and the plate material 20, and the interior of the preform 40 and the flow path 98 communicate with each other.

  Thereafter, the upper mold 70 that has been retracted to the standby position descends and approaches the lower mold 80, whereby the upper mold 70 and the lower mold 80 are clamped (see FIG. 8). At this time, the dome-shaped portion 12 of the plate member 10 is fitted to the distal end portion 76A of the concave portion 76 located in the pressing portion 75 of the upper mold 70, and the vicinity of the dome-shaped portion 12 is the pressing portion of the upper mold 70. 75 and the circular convex portions 94 and 95 in the nozzle portion 91 disposed in the concave portion 86 of the lower mold 80. As a result, a bent portion is formed in an annular shape in the vicinity of the dome-shaped portion 12, and a sealing property for the introduced forming medium is secured.

  The hydraulic pressure supply means 90 introduces the molding medium supplied from the hydraulic pressure circuit 99 into the preform 40 through the nozzle portion 91 and applies the hydraulic pressure to the cavity surfaces 71 and 81. The portion of the preform 40 located inside is bulged and deformed (see FIGS. 9 and 10).

  At this time, the part located in the vicinity of the boundary of the mold dividing surface is greatly deformed while the material flows. In addition, the parts of the preform 40 that are held by the pressing portions 75 and 85 of the upper mold 70 and the lower mold 80 move toward the cavity surfaces 71 and 81, thereby causing material inflow. Therefore, the reduction of the plate thickness is excessively progressed, and the material is ruptured or the joint 41 is prevented from being cracked.

  On the other hand, the portion where the reinforcing member 30 is welded is located in a region pressed against the bottom 74 of the cavity surface 71. That is, the portion to which the reinforcing member 30 is welded is located far from the boundary of the mold dividing surface and is located at a non-flowing portion where the material does not substantially flow. It is pressed so as to stick toward the bottom 74. Therefore, peeling of the reinforcing material 30 and generation of wrinkles due to the bulging deformation of the preform 40 are suppressed.

  Further, since the distortion of the plate members 10 and 20 or the preform 40 caused by the thermal shrinkage caused by the welding of the reinforcing member 30 is corrected when the preform 40 is bulged and deformed, the accuracy of the obtained molded product is improved. Will not be affected.

  When the inside of the preform 40 reaches the final hydraulic pressure Pmax, the supply of the forming medium is stopped and held for a predetermined time, whereby the bulge of the preform 40 is completed (see FIG. 11). Then, after the pressure is released, the upper mold 70 is raised, the mold is opened, and trimming such as cutting is performed, whereby a molded product having good accuracy can be obtained. Accordingly, an independent facility or process for correcting the distortion is not required, so that the productivity is not lowered and the manufacturing cost is not increased.

  The reinforcing material 30 is pressed against the bottom 74 of the cavity surface 71 during the bulging deformation, so that the region where the reinforcing material 30 is welded is depressed toward the mating surface of the plate members 10 and 20. A recess is formed. Since the reinforcing material 30 is buried in the concave portion, the surface of the reinforcing material 30 and the surface of the portion adjacent to the reinforcing material 30 (the portion adjacent to the concave portion) are located on substantially the same plane. Therefore, for example, when other parts such as a bracket are attached, interference due to the presence of the reinforcing member 30 is suppressed.

  As described above, the present embodiment can provide a hydraulic forming method for easily obtaining a molded product having strength and rigidity partially reinforced and having good accuracy.

Next, with reference to FIG. 12 to FIG. 15, modified examples 1 to 4 according to the embodiment of the present invention will be described. The portion to which the reinforcing member 30 is welded is not particularly limited. It is preferable to be located at a non-flowing portion where the flow of the liquid hardly occurs. The part of the plate material pressed against the transition part on the cavity surface of the molding die is located at a non-flowing part where the material does not substantially flow, like the part pressed against the bottom part. Therefore, as shown in the cross-sectional view of FIG. 12, it is possible to weld the reinforcing member 30 in advance to the region to be pressed by the transition portion and the bottom portion of the cavity surface.

  Further, the number and shape of the reinforcing members 30 can be appropriately set as necessary. For example, as shown in the plan view of FIG. 13, a plurality of reinforcing members 30 can be arranged.

  Furthermore, the surface to which the reinforcing member 30 is welded is not limited to the outer surface located on the opposite side of the mating surface of the plate material, but is the inner surface located on the mating surface of the plate material as shown in the sectional view of FIG. Is also possible.

  Moreover, when forming the recessed part corresponding to the shape of the reinforcing material 30 in the cavity surface of the molding die facing the reinforcing material 30, as shown in the sectional view of FIG. It is possible to obtain a molded product in which the surface of the part adjacent to 30 is not on the same plane.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims.

  For example, the plate material and the reinforcing material are not limited to being composed of the same material, but the plate material can be composed of a material having good moldability, and the reinforcing material can be composed of a material having good strength and rigidity. It is.

It is a perspective view for demonstrating the molded article which concerns on embodiment of this invention. It is a top view for demonstrating the preforming body which concerns on embodiment of this invention. FIG. 3 is a rear view of the preform shown in FIG. 2. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2. It is sectional drawing for demonstrating the hydraulic forming apparatus which concerns on embodiment of this invention. It is a top view for demonstrating the upper mold | type of the hydraulic forming apparatus shown by FIG. It is a top view for demonstrating the lower mold | type of the hydraulic-molding apparatus shown by FIG. It is sectional drawing for demonstrating the hydraulic forming method which concerns on embodiment of this invention, and has shown clamping. It is sectional drawing for demonstrating the shaping | molding initial stage following FIG. It is sectional drawing for demonstrating the shaping | molding middle period following FIG. It is sectional drawing for demonstrating the shaping | molding latter stage following FIG. It is sectional drawing for demonstrating the modification 1 which concerns on embodiment of this invention. It is a top view for demonstrating the modification 2 which concerns on embodiment of this invention. It is sectional drawing for demonstrating the modification 3 which concerns on embodiment of this invention. It is sectional drawing for demonstrating the modification 4 which concerns on embodiment of this invention.

Explanation of symbols

10. Plate material,
11, 16, ... end,
12..Dome part,
15. Central part,
20. Plate material
21, 26 .. end,
22 .. opening,
25 ... Central part,
30. ・ Reinforcing material,
31..Junction part,
40 .. Pre-formed body,
41..Junction part,
50. ・ Molded products,
51 .. Flange part,
52 .. Joint part,
60 .. Hydraulic forming device,
70 .. Upper mold,
71 .. cavity surface,
72 .. side part,
73 .. Transition Department,
74 .. Bottom
75..Pressing part,
76 .. Recess,
76A ... tip part,
77, 78 .. Arc-shaped groove,
80 ... lower mold,
81 .. cavity surface,
82 .. side part,
83 .. Transition Department,
84 ... the bottom,
85..Pressing part,
86..Recess,
90 .. hydraulic supply means,
91 .. Nozzle part,
92 .. Domed part,
93..Inlet,
94, 95 .. annular projection,
98 .. flow path,
99 ... Hydraulic circuit,
Pmax ... Final hydraulic pressure.

Claims (11)

A hydroforming method to which a preformed body having two overlapping plate materials joined at the periphery is applied,
After welding a reinforcing material to at least one of the plate members, the preform is placed inside a molding die and clamped, and hydraulic pressure is applied to the inside of the preform to bulge and deform. A hydraulic forming method characterized by comprising:   The hydraulic forming method according to claim 1, wherein the periphery of the plate material is joined after the reinforcing material is welded.   3. The liquid according to claim 1, wherein a region of the plate member to which the reinforcing material is welded is located at a non-flowing portion where the material does not substantially flow during the bulging deformation. Pressure forming method.   The cavity surface of the molding die has a substantially flat bottom portion disposed at a central portion, and the non-flowing portion of the plate material is a portion pressed against the bottom portion. Hydraulic forming method.   The cavity surface of the mold has a side surface extending from the boundary of the mold dividing surface, a substantially flat bottom, and a bent transition portion positioned between the side surface and the bottom, and the plate material The non-flow part of this is a part pressed by the said transition part and the said bottom part, The hydraulic forming method of Claim 3 characterized by the above-mentioned.   The hydraulic forming method according to claim 1, wherein the reinforcing material is disposed on an outer surface located on the opposite side of the mating surface of the plate members.   The hydraulic molding method according to claim 6, wherein the reinforcing material is buried in the plate material by being pressed against a bottom portion of a cavity surface of the molding die.   The hydraulic forming method according to claim 7, wherein the reinforcing material is in a sheet form.   The hydraulic molding method according to claim 6, wherein a cavity surface of the molding die facing the reinforcing material has a recess corresponding to the shape of the reinforcing material.   The hydraulic molding method according to claim 1, wherein the reinforcing material is disposed on an inner surface located on a mating surface of the plate material.   The hydraulic forming method according to claim 1, wherein the plate member and the reinforcing member are made of different materials.

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