JP4837430B2 - Hydroform apparatus and method - Google Patents

Description

  The present invention relates to a hydroforming apparatus and method for applying a hydraulic pressure to a pipe housed in a mold and expanding a predetermined portion of the pipe to a curved shape.

  Hydroforming may be used when the pipe material (pipe material) is expanded in the radial direction. In this hydroform molding, after the pipe material is accommodated in a mold having recesses in accordance with the expanded pipe shape (product shape), the liquid is sealed in the pipe material and the hydraulic pressure is applied to the pipe material in the axial direction. It is performed by pressing (pressing) and deforming (expanding) a part of the pipe material (for example, see Patent Document 1).

JP-A-56-99026

  By the way, when the tube expansion ratio is relatively large (for example, about 2 or more), since the gap between the tube material before molding and the concave portion of the mold is large, the tube material does not deform uniformly (the plate thickness does not decrease uniformly). , Easy to burst. Therefore, when the pipe expansion ratio is relatively large, the mold (counter punch) is moved in accordance with the deformation of the pipe material, and the pipe material is pressed by the mold (counter punch) to prevent rupture.

  However, when expanding the pipe material into a hemispherical shape, it is impossible to mold the pipe material into a hemispherical shape with a mold (counter punch) having a circular plane used for hydroforming of a T-shaped tube.

  Accordingly, an object of the present invention is to provide a hydroform apparatus and method capable of expanding a pipe material into a curved surface shape with a large expansion ratio.

  In order to achieve the above-mentioned object, the invention according to claim 1 is a hydroforming apparatus in which a liquid pressure is applied to a pipe material accommodated in a mold to expand a predetermined portion of the pipe material into a curved shape. A plurality of counter-punch portions that are arranged in parallel in the tube forming portion and are movable in the radial direction of the tube material, a guide for guiding the counter punch portion in the radial direction of the tube material, and each counter punch portion of the tube material A hydroforming apparatus comprising: pressing means for pressing against the outer periphery; and restricting means for sequentially restricting movement of each counter punch portion so that a predetermined portion of the pipe material is expanded into a curved shape. It is.

  The invention according to claim 2 is the hydroforming apparatus according to claim 1, wherein the counter punch portion is formed in a plate shape or a ring shape.

  According to a third aspect of the present invention, there is provided a hydroforming method in which a hydraulic pressure is applied to a pipe material accommodated in a mold and a predetermined portion of the pipe material is expanded into a curved surface. A plurality of counter punch portions each movable in the direction are arranged side by side, and the counter punch portion is radially outward according to deformation of the tube material while the tip end portion of the counter punch portion is in contact with the outer peripheral surface of the tube material. The hydroforming method is characterized in that the movement of each counter punch portion is sequentially regulated so that a predetermined portion of the pipe material is expanded into a curved surface shape.

  The invention according to claim 4 is the hydroforming method according to claim 3, wherein the counter punch portion is formed in a plate shape or a ring shape.

  According to the present invention, there is an excellent effect that the pipe material can be expanded into a curved surface shape with a large expansion ratio.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  The hydroforming apparatus of the present embodiment is for applying a hydraulic pressure to a pipe housed in a mold and expanding a predetermined portion of the pipe to a curved shape such as a hemispherical shape or an arc shape.

  FIG. 1 is a front sectional view of a hydroforming apparatus according to an embodiment of the present invention, FIG. 1 (a) shows a state before molding, and FIG. 1 (b) shows a state after molding. FIG. 2 is a plan sectional view of the hydroforming apparatus, FIG. 2 (a) shows a state before molding, and FIG. 2 (b) shows a state after molding.

  The hydroforming apparatus of this embodiment is for molding an axle housing of a truck.

  As shown in FIG. 5, the axle housing 1 bulges in the center in the longitudinal direction in a substantially hemispherical shape in the rearward direction of the vehicle (see FIG. 5 (a)) and bulges in a substantially arc shape in the vertical direction of the vehicle. The banjo part 2 is provided (refer FIG.5 (b)).

  As shown in FIGS. 1 and 2, the hydroform apparatus 10 includes a mold 12 for housing the pipe material 11, and a hydraulic pressure adding means 13 for applying hydraulic pressure to the pipe material 11 accommodated in the mold 12. And a pressing means 14 for pressing the tube material 11 accommodated in the mold 12 in the axial direction (left-right direction in FIGS. 1 and 2).

  The hydraulic pressure adding means 13 adds a hydraulic pressure (internal pressure) to the pipe 11 by enclosing a liquid (for example, water or oil) in the pipe 11. The hydraulic pressure adding means 13 is attached to both ends of the hydraulic pump (not shown), the pipe material 11, a pair of sealing members 15 for sealing the pipe material 11, and one end connected to the hydraulic pump, The other end has a pipe 16 connected to the sealing member 15. Each sealing member 15 is formed with a through hole 17 that communicates the inside and outside of the tube material 11, and the liquid from the hydraulic pump is sealed in the tube material 11 through the pipe 16 and the sealing member 15 (through hole 17). The

  The pressing means 14 presses the tube material 11 in the axial direction by compressing the tube material 11 in the axial direction. The pressing means 14 has a pressing cylinder 18 (for example, a hydraulic cylinder) for compressing the tube material 11 in the axial direction. The tip of the rod 19 of the pressing cylinder 18 is brought into contact with the sealing member 15, and the pressing cylinder 18 compresses the tube material 11 in the axial direction via the sealing member 15.

  As shown in FIGS. 3 and 4, the mold 12 is vertically divided into two, and is composed of an upper mold 20 and a lower mold 21. The mating surfaces of the upper mold 20 and the lower mold 21 respectively support recesses (expansion forming portions) 20a and 21a for expanding a predetermined portion (center portion) of the tube material 11 and non-processed portions of the tube material 11. Recesses (tube material support portions) 20b and 21b are formed.

  As shown in FIG. 3, in the tube expansion forming portion 20 a of the upper mold 20, in order to form a bulging shape (hemispherical shape) in the rear direction of the vehicle in the banjo portion 2 of the axle housing 1, A plurality of counter punches (counter punch portions) 22 that are movable in each direction are arranged in parallel. Each counter punch 22 is formed in a ring shape. The front end surface of each counter punch 22 that comes into contact with the tube material 11 is formed in a substantially arc shape in cross section.

  The number of counter punches 22 is appropriately set according to the plate thickness and diameter of the tube material 11, the curvature of the bulge shape (hemispheric shape) to be formed, and the like. In the present embodiment, four counter punches 22 are arranged side by side.

  The upper mold 20 is provided with a fall prevention means for preventing the counter punches 22 from dropping. The fall prevention means is an annular stopper (first stopper) that is provided on the outer periphery of each counter punch 22 and protrudes radially outward in order to prevent the counter punches 22 other than the outermost counter punch 22 from falling off. 23 and a pin-like stopper (second stopper) 24 that is attached to the upper die 20 and protrudes radially inward in order to prevent the outermost counter punch 22.

  A guide is provided for guiding the counter punch 22 in the radial direction (upward in the present embodiment) of the tube material 11. That is, the counter punch 22 is pushed by the tube material 11 that is deformed (bulged) by the applied hydraulic pressure, and is moved upward along the guide 25. Each counter punch 22 except for the outermost counter punch 22 is guided by the outer peripheral surface and inner peripheral surface of the adjacent counter punch 22, and the outermost counter punch 22 is guided by the outer peripheral surface of the adjacent counter punch 22 and the upper die 20. It is guided by the inner peripheral surface of the hole 25 provided in the.

  The counter punch 22 is radially inward (in this embodiment, downward) by a predetermined force by a pressing cylinder 26 (for example, a hydraulic cylinder) as a pressing means for pressing each counter punch 22 against the outer peripheral surface of the pipe material 11. ). That is, the counter punch 22 is pushed downward by the holding cylinder 26 and applies a predetermined external pressure to the tube material 11. A plate-shaped counter punch receiver 28 is attached to the tip of the rod 27 of the holding cylinder 26, and the tip of the counter punch receiver 28 is brought into contact with the rear end of each counter punch 22.

  The upper mold 20 is provided with a regulating means for sequentially regulating the movement of each counter punch 22 so that the central portion of the tube material 11 is expanded into a substantially hemispherical shape. The restricting means is provided on the upper die 20 and includes a stepped portion 29 with which the rear end portion of each counter punch 22 abuts, and the counter punch 22 is sequentially restricted from the radially outer side. Yes.

  As shown in FIG. 4, in the tube forming portion 21 a of the lower mold 21, in order to form a bulging shape (arc shape) in the vehicle vertical direction in the banjo portion 2 of the axle housing 1 into the tube material 11, the diameter of the tube material 11. A plurality of counter punches (counter punch portions) 30 movable in the direction are arranged in parallel. Each counter punch 30 is formed in a plate shape. The front end surface of each counter punch 30 that comes into contact with the tube material 11 is formed in a substantially arc shape in cross section.

  The number of counter punches 30 is appropriately set according to the plate thickness and diameter of the tube material 11, the curvature of the bulge shape (arc shape) to be formed, and the like. In the present embodiment, seven counter punches 30 are arranged side by side.

  The lower mold 21 is provided with pop-out prevention means for preventing the counter punches 30 from jumping to the tube material 11 side. The pop-out preventing means is provided on the lower mold 21 and includes a stepped portion (third stopper) 31 protruding upward.

  The lower die 21 is provided with a guide for guiding the counter punch 30 in the radial direction of the pipe material 11 (in the present embodiment, on the side). That is, the counter punch 30 is pushed by the tube material 11 that is deformed (bulged) by the applied hydraulic pressure, and is moved sideways along the guide. Each counter punch 30 except for the axially outermost counter punch 30 is guided by the side surface of the adjacent counter punch 30, and the axially outermost counter punch 30 includes the side surface of the adjacent counter punch 30 and the lower die 30. It is guided by the side surface of the recess 32 provided in the.

  The counter punch 30 is radially inward (in this embodiment, a side) by a predetermined force by a pressing cylinder 33 (for example, a hydraulic cylinder) as a pressing means for pressing each counter punch 30 against the outer peripheral surface of the pipe material 11. )). That is, the counter punch 30 is pushed to the side by the holding cylinder 33 so as to apply a predetermined external pressure to the tube material 11. A plate-shaped counter punch receiver 35 is attached to the tip of the rod 34 of the holding cylinder 33, and the tip of the counter punch receiver 35 is brought into contact with the rear end of each counter punch 30.

  The lower mold 21 is provided with a regulating means for sequentially regulating the movement of each counter punch 30 so that the central portion of the pipe material 11 is expanded into a substantially arc shape. The restricting means is provided on the lower die 21 and is composed of a stepped portion 36 with which the rear end portion of each counter punch 30 abuts, and the counter punch 30 is sequentially restricted from moving outward in the axial direction. Yes.

  Next, the hydroforming method of this embodiment will be described.

  When the axle housing 1 shown in FIG. 5 is molded from the pipe material 11 using hydroforming, the pipe expansion ratio in the banjo part 2 of the axle housing 1 is relatively large.

  Therefore, the axle housing 1 can be manufactured without rupturing the tube material 11 by performing preforming using the hydroform apparatus 10 described above.

  First, as a pre-formation process (first process), the hydroform device 10 is used to expand the central portion of the tube material 11, and the bulge shape (hemispherical shape) in the vehicle rear direction in the banjo portion 2 and the banjo portion A primary molded product having a bulge shape (arc shape) in the vehicle vertical direction in 2 is formed.

  As shown in FIGS. 1 (a) and 2 (a), sealing members 15 are attached to both ends of the tube material 11, and the tube material 11 is placed between the upper mold 20 and the lower mold 21 of the mold 12 (expansion forming portion). 20a, 21a and the space defined by the pipe material support portions 20b, 21b). A predetermined load is applied to the upper mold 20 in order to prevent the upper mold 20 from floating due to the hydraulic pressure applied to the tube material 11.

  Next, the hydraulic pump is operated to apply a predetermined hydraulic pressure (internal pressure) to the tube material 11, and the pressing cylinder 18 is extended to press the tube material 11 in the axial direction. As a result, the central portion in the axial direction of the tube material 11 is expanded in the radial direction, and the outer peripheral portion of the tube material 11 contacts the tube expansion forming portions 20a and 21a and the counter punches 22 and 30.

  Here, at the initial stage of molding, the tube material 11 is expanded with a gap between the tube material 11 and the tube expansion forming portions 20a and 21a and the counter punches 22 and 30, but the tube material 11 and the tube expansion forming portions 20a and 21a are expanded. In addition, since the gap between the counter punches 22 and 30 is sufficiently small (that is, the tube expansion ratio is small) and the tube material 11 is sufficiently thick at the initial stage of molding, there is no possibility that the pipe material 11 will burst at the initial stage of molding.

  Next, when the pressing cylinder 18 is further extended, the holding cylinders 26 and 33 provided on the upper mold 20 and the lower mold 21 are retracted due to the deformation (bulging) of the tube material 11. That is, the counter punches 22 and 30 provided on the upper mold 20 and the lower mold 21 are moved radially outward in accordance with the deformation (bulging) of the tube material 11. Since the pipe 11 is expanded while applying a predetermined external pressure to the pipe 11 by the counter punches 22 and 30, the pipe 11 can be uniformly deformed (the thickness of the pipe 11 can be reduced uniformly). It is possible to expand the tube with a large expansion ratio.

  The movement of the counter punch 22 provided on the upper die 20 is sequentially regulated by the step portion 29 from the radially outer one, and the counter punch 30 provided on the lower die 21 is stepped from the axially outer one. The movement is sequentially regulated by the portion 36, and the shape of the surface defined by the tip portions of the counter punches 22 and 30 is gradually changed from the planar shape to the curved surface shape. As the surface shape of the tip of the counter punches 22 and 30 changes, the outer periphery of the tube material 11 changes from a flat shape to a curved surface shape, and the curvature of the curved surface shape gradually increases (the radius of curvature gradually decreases). To go). Therefore, the pipe material 11 can be expanded into a curved shape.

  As shown in FIGS. 1B and 2B, the movement of all counter punches 22 and 30 is restricted by the stepped portions 29 and 36 on the holding cylinders 26 and 33 provided on the upper die 20 and the lower die 21. When it is degenerated until it is done, the shape of the surface defined by the tip portions of the counter punches 22 and 30 becomes the target tube expansion shape. Accordingly, a primary molded product having a bulge shape (arc shape) in the vehicle up-down direction in the banjo portion 2 and a bulge shape (hemispheric shape) in the vehicle rear direction in the banjo portion 2 is obtained.

  Next, as the final molding process (second process), the primary molded product is accommodated in a mold having a recess according to the expanded pipe shape (product shape), and hydraulic pressure is applied to the primary molded product. However, the primary molded product is pressed in the axial direction to obtain a secondary molded product. In the mold 12 shown in FIGS. 3 and 4, the R shape of the shoulder portion (corner portion) (see reference numeral 3 in FIG. 5) of the banjo portion 2 in the axle housing 1 cannot be reduced. Shape the shoulder 3 of the banjo 2.

  Furthermore, as a final step, an insertion port for inserting a driving mechanism such as a differential by cutting a surface facing the hemispherical surface at the center of the secondary molded product (see reference numeral 4 in FIG. 5). Form.

  Thus, the axle housing 1 as shown in FIG. 5 is obtained.

  According to this method, since there is no welded portion in the axle housing 1, it is possible to obtain the axle housing 1 having high durability strength reliability and light weight at low cost.

  In order to confirm the effect of preventing the pipe material from bursting according to the present embodiment, a simulation for molding the axle housing was performed. In the simulation, it was simulated that the central portion of a pipe material (element tube) of φ89 mm was expanded to φ196 mm with a pipe expansion ratio of about 2. The tube material was STKM11A (heat treatment material), and the plate thickness was 2.9 mm. In the axle housing to be molded, the height of the bulge shape (hemispheric shape) in the rearward direction of the vehicle in the banjo part was set to 35 mm, and the diameter of the bulge shape (arc shape) in the vehicle vertical direction in the banjo part was set to 170 mm. The thickness reduction rate of 33% was taken as the fracture limit. In the present embodiment, the maximum reduction rate of the plate thickness was 30%.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various other embodiments can be adopted.

FIG. 1 is a front cross-sectional view of a hydroform apparatus, FIG. 1 (a) shows a state before molding, and FIG. 1 (b) shows a state after molding. FIG. 2 is a plan sectional view of the hydroforming apparatus, FIG. 2 (a) shows a state before molding, and FIG. 2 (b) shows a state after molding. It is a perspective view of the upper mold | type of a metal mold | die. It is a perspective view of the lower mold | type of a metal mold | die. FIG. 5 shows an axle housing, FIG. 5 (a) is a front view, and FIG. 5 (b) is a plan view.

Explanation of symbols

10 Hydroform equipment 11 Pipe 20 Upper mold (mold)
20a Concave part (tube expansion forming part)
21 Lower mold (mold)
21a Concave part (tube expansion forming part)
22 Counter punch (Counter punch part)
25 holes (guide)
26 Pressing cylinder (pressing means)
29 Stepped part (regulation means)
30 Counter punch (Counter punch part)
32 Recess (Guide)
33 Holding cylinder (holding means)
36 Stepped part (regulating means)

Claims (4)

In a hydroform apparatus that applies hydraulic pressure to the pipe material accommodated in a mold and expands a predetermined portion of the pipe material into a curved shape,
A plurality of counter punch portions arranged in parallel in the pipe expansion forming portion of the mold and movable in the radial direction of the pipe material, a guide for guiding the counter punch portion in the radial direction of the pipe material, and each counter punch portion A pressing means for pressing the pipe against the outer periphery of the pipe material, and a regulating means for sequentially regulating the movement of each counter punch part so that a predetermined portion of the pipe material is expanded into a curved shape. Hydroform equipment to do.   The hydroforming apparatus according to claim 1, wherein the counter punch portion is formed in a plate shape or a ring shape. In the hydroforming method of applying a hydraulic pressure to the pipe material accommodated in the mold and expanding a predetermined portion of the pipe material into a curved shape,
A plurality of counter punch portions movable in the radial direction of the pipe material are arranged in parallel in the pipe expansion forming portion of the mold,
The counter punch portion is moved radially outward in accordance with the deformation of the tube material while the tip portion of the counter punch portion is in contact with the outer peripheral surface of the tube material, A hydroforming method characterized by sequentially regulating predetermined portions to be expanded into a curved shape. The hydroforming method according to claim 3, wherein the counter punch portion is formed in a plate shape or a ring shape.

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