JP6763606B2 - Hydroforming equipment and hydroforming method - Google Patents

Description

The present invention relates to a bulge forming apparatus and a bulge forming method for deforming the peripheral surface of a tube body into a convex shape engraved in the die by pressurizing the inside of the tube body housed in the mold.

Urethane bulge molding is known as a molding method for deforming the peripheral surface of a tubular body into a predetermined convex shape. In the conventional urethane bulge molding, the tube body is housed in a mold in which a predetermined concave shape is engraved on the inner surface, the urethane rubber is inserted inside the tube body, and then the urethane rubber is expanded to make the tube body gold. It is pressed against the mold and the peripheral surface of the tube is deformed into a convex shape so as to follow the concave shape carved in the mold.

A concave shape is engraved on the inner surface of the mold by electric discharge machining or cutting using an NC three-dimensional processing machine. Further, the mold is divided into a plurality of pieces in a plane orthogonal to the axial direction of the pipe body in consideration of the storage and removal of the pipe body.

Japanese Unexamined Patent Publication No. 2005-313187

However, in the conventional hydroforming, electric discharge machining and cutting are used to engrave the concave shape on the inner surface of the mold, so that the mold production work takes a long time. Further, when the mold is divided into a large number in order to improve the roundness of the pipe body after molding, a concave shape corresponding to a pattern to be formed on the peripheral surface of the pipe body straddles the inner surfaces of the plurality of molds. May need to be formed. In this case, a plurality of molds must be manufactured with high dimensional accuracy so that the seams between the adjacent molds do not appear in the design of the tube. Further, when the concave shape is worn due to repeated molding operations, it becomes necessary to replace the entire mold. These increase the cost of hydroforming.

Such a problem occurs not only in urethane bulging molding using urethane rubber, but also in all bulging molding including hydroforming using a low-compressibility or incompressible fluid having a small volume change during deformation.

An object of the present invention is to configure a mold with an inner mold of a plate material interposed between an outer surface of a tubular body on which a convex shape is formed and an inner surface of a plurality of outer molds that constrain the tubular body in the radial direction. By doing so, it is an object of the present invention to provide a bulge forming apparatus and a bulge forming method capable of simplifying the manufacturing work of the mold, preventing the wear of the mold, and realizing the cost reduction.

The hydroforming apparatus of the present invention includes a plurality of outer molds, inner molds, and pressurizing mechanisms. The plurality of outer molds are arranged reciprocally in the directions of approaching and separating from each other along the radial direction of the tubular body in each region obtained by dividing the outer peripheral portion of the tubular body into a plurality of portions along the circumferential direction. The inner mold is made of at least one metal flat plate and is arranged between the inner peripheral surface of the outer mold and the outer peripheral surface of the pipe body. The outer mold constrains the tube in the radial direction with the inner mold in between. The pressurizing mechanism pressurizes the inside of the tube body arranged in the inner mold.

In the bulge forming method of the present invention, a plurality of regions in which the outer peripheral portion of the tubular body is divided into a plurality of regions along the circumferential direction are reciprocally arranged in directions approaching and separating from each other along the radial direction of the tubular body. And the inner mold arranged in a part between the inner peripheral surface of the outer mold and the outer peripheral surface of the pipe body using at least one metal flat plate as a material, and the pipe body arranged in the inner mold. A pressurizing mechanism for pressurizing the inside of the tube is prepared, and the inside of the tube is pressurized by the pressurizing mechanism with the inner die interposed between the tube and the outer die.

When the inside of the tube is pressurized by the pressurizing mechanism with the inner die interposed between the tube and the outer die, the part of the outer peripheral surface of the tube where the inner die does not exist expands outward. Then, a convex shape is formed. Since the inner mold is made of at least one metal flat plate, a concave shape corresponding to the convex shape to be formed on the pipe body can be easily formed.

In this configuration, the pressurizing mechanism includes a pressurizing member made of a low-compressible or incompressible fluid or flexible material having a small volume change during deformation, and a pressing member that presses the pressurizing member in the axial direction of the tubular body. , It can be composed of a closing member that closes the first end portion in the axial direction of the pipe body.

After inserting the pressurizing member from the second end into the inside of the tubular body in which the first end is closed by the closing member, the pressurizing member is pressed in the axial direction of the tubular body by the pressing member. The inside of the can be pressurized in the radial direction.

The inner mold can be a metal flat plate having a concave opening corresponding to the convex shape to be formed in the tubular body.

A mold corresponding to the convex shape to be formed on the pipe body can be easily manufactured at low cost, wear of the outer mold can be prevented, and replacement work when the inner mold is worn becomes easy.

Using a metal flat plate as a material, it is provided with two or more inner molds that are arranged in close contact with each other in the thickness direction over the entire circumference between the inner peripheral surface of the plurality of outer molds and the outer peripheral surface of the pipe body. The inner mold located at least on the innermost side of the inner mold may have an opening having a shape corresponding to the convex shape to be formed on the tubular body.

By forming openings in two or more inner molds, a stepped convex shape can be formed on the peripheral surface of the pipe body. Further, by not forming an opening in the inner mold located on the outermost side of the two or more inner molds, the outer peripheral surface of the tubular body deformed by the pressurization of the pressurizing member does not come into direct contact with the outer mold. , No wear on the outer mold.

According to the present invention, it is possible to realize the simplification of the production work of the mold, prevent the wear of the mold, and realize the cost reduction.

It is sectional drawing of the bulge forming apparatus which concerns on embodiment of this invention. (A) and (B) are an external view of a second plate material of the bulge forming apparatus, and an external view of a pipe body formed by the bulge forming apparatus. (A) to (C) are sectional views which show the bulge forming method which concerns on embodiment of this invention. It is external drawing of the 1st and 2nd plate material of the bulge forming apparatus which concerns on another embodiment of this invention. (A) and (B) are external views of the second plate material of the bulge forming apparatus according to still another embodiment of the present invention. It is sectional drawing which shows the deformed state of the pressure member using the integrated urethane in the bulge forming apparatus which concerns on embodiment of this invention. It is sectional drawing which shows the deformed state of the pressure member using the split type urethane in the bulge forming apparatus which concerns on embodiment of this invention.

The bulge forming apparatus and bulge forming method according to the embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the hydroforming apparatus 10 according to the embodiment of the present invention includes a base 1, a driving member 2, an outer mold 3, a first plate material 4, a second plate material 5, urethane rubber 6, and a plunger 7. A ring 8 is provided, and a convex shape is formed on the peripheral surface of the tubular body 20 by urethane bulge forming.

The base 1 has a disk shape as an example, and the first convex portion 11, the second convex portion 12, and the hole portion 13 are formed concentrically in the central portion, and 4 at equal intervals in the circumferential direction of the outer portion. Female threaded portions 14 are formed at the locations (only two locations appear in FIG. 1). The first convex portion 11 and the second convex portion 12 project upward from the upper surface of the base 1.

The lower end of the shaft portion 73 of the plunger 7 penetrates through the hole portion 13 from above. A fixing screw 15 is screwed into the lower end surface of the shaft portion 73 exposed below the hole portion 13 via a washer 16. The washer 16 abuts on the lower edge of the hole 13 to define the upper limit position of the plunger 7. A bolt 21 is screwed into the female screw portion 14. The second convex portion 12 is the closing member of the present invention, has an outer diameter equal to the inner diameter of the tubular body 20, and the lower end portion, which is the second end portion of the tubular body 20, is fitted and closed. ..

As an example, the driving member 2 is a tubular body having a conical shape on the inner peripheral surface, and four locations (only two locations in FIG. 1) appear at equal intervals in the circumferential direction of the flange 22 formed at the lower end portion. ) Is formed with a through hole 23. The bolt 21 is screwed into the female threaded portion 14 after the threaded portion is passed through the through hole 23. The drive member 2 is movable in the vertical direction within a predetermined range on the base 1 in a state where the movement in the plane is restricted by the bolt 21.

Each of the outer molds 3 is composed of a total of four outer molds 3 located in a region equally divided into four parts, taking the outer peripheral portion of the pipe body 20 as an example. The outer peripheral surface of each outer die 3 is formed in the same conical shape as the inner peripheral surface of the drive member 2. The inner peripheral surface of each outer mold 3 is formed in a cylindrical shape having an inner diameter larger than the outer diameter of the tubular body 20. The bottom surface of each outer die 3 is in contact with the upper surface of the base 1, and the outer die 3 is reciprocally movable only in the radial direction of the tubular body 20 via a key (not shown). Further, a step portion 31 into which the first convex portion 11 is fitted is formed on the bottom portion of each outer mold 3.

As an example, the outer molds 3 are urged in a direction in which they are separated from each other by the elastic force of an elastic member (not shown) arranged between them. Due to this elastic force, each outer mold 3 is urged outward on the base 1. Since the outer peripheral surface of each outer mold 3 is formed in the same conical shape as the inner peripheral surface of the drive member 2, when the drive member 2 is lowered, each outer mold 3 is formed along the radial direction of the tubular body 20. They move so as to approach each other, and when the driving member 2 is raised, the outer molds 3 move so as to be separated from each other along the radial direction of the tubular body 20.

The drive member 2 may individually drive each of the four outer molds 3. Further, the inner surface of the drive member 2 can be formed of a flat inclined surface. In this case, the outer surface of each outer mold 3 is formed by a flat inclined surface that always abuts on the inner surface of the drive member 2. Form. Further, the drive member 2 may be a plurality of members located in a region in which the outer peripheral portion of the tubular body 20 is equally divided into a plurality of members, and may be configured to move in the radial direction of the tubular body 20.

Each of the first plate material 4 and the second plate material 5 corresponds to the inner mold of the present invention, and is, for example, a metal flat plate made of SUS304 having a plate thickness of 1 mm and curved in a cylindrical shape. The first plate material 4 and the second plate material 5 are inserted into the outer mold 3 in a state of being stacked with the first plate material 4 on the outside. As an example, in the first plate material 4, the entire outer surface of the first plate member 4 faces the inner peripheral surface of the outer mold 3. The second plate material 5 includes an opening 51 as shown in FIG. 2A as an example. The opening 51 has a shape corresponding to the convex shape 24 to be formed on the outer peripheral surface of the tubular body 20 shown in FIG. 2 (B).

The inner diameter of the outer mold 3 is set to a size obtained by adding twice the sum of the plate thicknesses of the first plate material 4 and the second plate material 5 to the outer diameter of the pipe body 20. Each of the first plate material 4 and the second plate material 5 does not necessarily have to be composed of one metal flat plate. It can also be divided into a plurality of pieces along the circumferential direction of the pipe body 20.

The urethane rubber 6 is a low-compressible flexible material that corresponds to the pressure member of the present invention and has a small volume change during deformation, and has a cylindrical shape with an outer diameter that substantially matches the inner diameter of the tubular body 20.

The plunger 7 is a pressing member of the present invention, and is configured by concentrically and integrally arranging a head portion 71, a disk portion 72, and a shaft portion 73. The outer diameter of the disk portion 72 is slightly smaller than the inner diameter of the tube body 20. The outer diameter of the shaft portion 73 is substantially equal to the inner diameter of the urethane rubber 6. The shaft portion 73 is formed with an exposed screw hole on the lower end surface. A fixing screw 15 is screwed into the screw hole. The plunger 7 constitutes the pressurizing mechanism of the present invention together with the urethane rubber 6 and the second convex portion 12.

The plunger 7 includes a shaft portion 73 whose upper limit position is positioned by a washer 16 in order to securely hold the urethane rubber 6, provided that the displacement of the urethane rubber 6 can be reliably regulated during urethane bulging. In addition, the shaft portion 73 can be omitted.

The ring 8 has an annular shape and fits into the recess 35 formed in the upper part of the outer mold 3. The inner peripheral surface of each outer mold 3 is maintained in a perfect circle over the entire length in the axial direction of the tubular body 20 by abutting with the ring 8 at the upper portion and abutting with the first convex portion 11 at the lower portion. The ring 8 may be omitted together with the first convex portion 11 on condition that the roundness of the outer mold 3 can be reliably maintained.

As shown in FIG. 3, the bulge forming method of the present invention can be carried out by using the bulge forming apparatus 10. First, the drive member 2 is positioned upward to separate the outer molds 3 from each other. At this time, the first plate material 4 and the second plate material 5 are housed inside each outer mold 3 in a state of being stacked with the first plate material 4 on the outside (FIG. 3 (A)).

Next, the pipe body 20 in which the urethane rubber 6 is inserted is inserted into the second plate member 5 (FIG. 3 (B)). The shaft portion 73 of the plunger 7 penetrates the urethane rubber 6.

From this state, the drive member 2 is lowered to bring the outer molds 3 closer to each other, and the pipe body 20 is pressed inward along the radial direction via the first plate material 4 and the second plate material 5, and the pipe is formed. The body 20 is constrained in the radial direction. After that, the plunger 7 is lowered via the head 71, and the upper end portion, which is the first end portion of the urethane rubber 6, is pressed from above along the axial direction via the disk portion 72 (FIG. 3C). ). Since the urethane rubber 6 is a flexible material having low compressibility, it presses the inner peripheral surface of the tubular body 20 toward the outside.

When the opening 51 is formed in the second plate member 5, the portion of the peripheral surface of the tubular body 20 facing the opening 51 is opened with the position where it abuts on the inner surface of the first plate member 4 as the maximum position. It passes through the inside of 51 toward the outside, and the other portion is formed into a perfect circle by abutting with the inner side surface of the second plate member 5. As a result, a convex shape corresponding to the shape of the opening 51 is formed on the peripheral surface of the tubular body 20.

As shown in FIG. 4, by forming an opening 41 smaller than the opening 51 in the portion of the first plate material 4 facing the opening 51, the opening 51 and the opening are formed on the peripheral surface of the tubular body 20. It is possible to form a two-stage convex shape according to the shape of 41.

When forming a convex shape on the peripheral surface of the tubular body 20, in the conventional bulge processing, it is necessary to form a concave shape corresponding to the convex shape on the inner peripheral surface of the mold by electric discharge machining or cutting, and the mold is manufactured. Not only the cost rises, but also the concave shape is deformed due to wear due to repeated bulge machining, and it is necessary to replace the mold regularly. On the other hand, in the bulge forming apparatus and the bulge forming method of the present invention, it is only necessary to form an opening having a shape corresponding to the convex shape to be formed on the peripheral surface of the tubular body 20 on the metal flat plate, and the production cost is low. Therefore, it is not necessary to replace the mold.

The inner mold of the present invention is not limited to the one composed of two metal flat plates of the first plate material 4 and the second plate material 5, and may be composed of three or more metal flat plates. In this case, when the bulge processing is repeated by not forming an opening in the plate material located on the outermost side and interposing the entire surface between the outer peripheral surface of the pipe body 20 and the inner peripheral surface of the outer mold 3. However, the outer mold 3 does not wear due to contact with the tubular body 20, and the outer mold 3 does not need to be replaced.

In addition, when bulge processing is used to form the tubular body 20 into a cylindrical shape with high roundness, only one plate material without an opening is used, so that even if the bulge processing is repeated, it is outside. The mold 3 does not wear due to contact with the tubular body 20, and the outer mold 3 does not need to be replaced.

The first plate member 4 and the second plate member 5 do not necessarily have to be arranged over the entire circumference between the outer peripheral surface of the pipe body 20 and the inner peripheral surface of the outer mold 3. For example, when a convex shape is formed on the peripheral surface of the tubular body 20 over the entire length in the axial direction, as shown in FIG. 5 (A), at least a part of the second plate member 5 in the circumferential direction extends over the entire length in the axial direction. It becomes unnecessary. Further, when a convex shape is formed over the entire circumference of a part of the peripheral surface of the tubular body 20 in the axial direction, at least a part of the second plate member 5 in the axial direction is completely formed as shown in FIG. 5 (B). The second plate member 5 is made up of two metal flat plates arranged vertically at intervals in the middle portion in the axial direction, which is unnecessary over the circumference.

As shown in FIG. 6, as in general urethane bulge molding, when urethane rubber 6 is used as a whole, when pressed in the axial direction by the plunger 7, the central portion of the urethane rubber 6 in the axial direction is the upper and lower ends. It tries to spread outside the part. Therefore, the radial pressing force acting on the inner peripheral surface of the tubular body 20 is large at the central portion in the axial direction of the tubular body 20 and small at the upper and lower end portions.

When there is a large difference in the radial pressing force acting on the inner peripheral surface of the tubular body 20 with respect to the axial direction of the tubular body 20, the inner peripheral surface of the tubular body 20 is radially oriented at the position facing the upper and lower ends of the opening 51. It cannot be sufficiently pressed toward the outside of the tube body 20, and the convex end portion to be formed on the outer peripheral surface of the tubular body 20 becomes dull. The blunting of the convex end portion does not pose a big problem when a concave portion is formed in the outer mold 3 to form a deep convex shape on the outer peripheral surface of the pipe body 20, but the plate material 5 in which the opening 51 is formed is formed. When a thin convex shape is formed on the outer peripheral surface of the tubular body 20 by using (including the plate material 4 having the opening 41 formed therein), there is a big problem as deterioration of the finish. This problem becomes particularly remarkable when the convex shape 24 to be formed on the outer peripheral surface of the tubular body 20 is long in the vertical direction.

Therefore, as shown in FIG. 7, the applicant uses the urethane rubber 61 divided into six parts as an example along the axial direction of the tubular body 20, so that when pressed in the axial direction by the plunger 7, the applicant can use it. It has been found that the radial spread of the urethane rubber 61 can be made substantially constant at the central portion and the upper and lower end portions in the axial direction. With this configuration, the radial pressing force acting on the inner peripheral surface of the tubular body 20 becomes substantially uniform over the entire axial direction of the tubular body 20, and the plate material 5 having the opening 51 (the plate material having the opening 41 formed). 4) is also used to form a thin convex shape long in the vertical direction on the outer peripheral surface of the tubular body 20, the occurrence of dullness at the end of the convex shape can be alleviated, and the finish of the convex shape can be improved. ..

The number of divisions of the urethane rubber 61 can be appropriately selected according to conditions such as the hardness of the material used, the material and plate thickness of the pipe body 20, and the convex shape to be formed on the outer peripheral surface of the pipe body 20. Further, the hardness of the urethane rubber 61 can be partially changed. For example, by making the hardness of the portion located at the upper and lower ends higher than that of the other portions, it is possible to prevent damage to the corner portion.

The description of the embodiments described above should be considered exemplary in all respects and not restrictive. The scope of the present invention is indicated by the scope of claims, not by the above-described embodiment. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the claims.

For example, although urethane rubber 6 is used in the above embodiment as the pressurizing member constituting the pressurizing mechanism of the present invention, incompressible or low compressibility generally used for bulging processing including hydroformink. A fluid or flexible material can be used as well.

1-Base 2-Drive member 3-Outer mold 4-First plate material (inner mold)
5-Second plate material (inner mold)
6-Urethane rubber (pressurized member)
7-Planger (pressing member)
10-Hydroforming device 12-2nd convex part (closing member)
20-tube

Claims (7)

In each region of the outer peripheral portion of the pipe body divided into a plurality of parts along the circumferential direction, a plurality of outer molds arranged reciprocally in the directions of approaching and separating from each other along the radial direction of the pipe body, and a plurality of outer molds.
An inner mold arranged between the inner peripheral surface of the plurality of outer molds and the outer peripheral surface of the pipe body using at least one metal flat plate as a material, and
A pressurizing mechanism that pressurizes the inside of the tubular body arranged in the inner mold,
The plurality of outer dies are bulge forming devices that constrain the pipe body in the radial direction with the inner dies sandwiched therein. The pressurizing mechanism includes a pressurizing member of a low-compressible fluid or flexible material inserted into the tubular body, and the pressurizing member along the axial direction from the first end side of the tubular body. The bulge forming apparatus according to claim 1, further comprising a pressing member that presses the pipe body and a closing member that closes the second end portion in the axial direction of the tubular body. The bulge forming apparatus according to claim 2, wherein the pressurizing member has a cylindrical shape inserted into the tubular body, and is a urethane rubber formed by being divided into a plurality of portions along the axial direction. Using a metal flat plate as a material, the inner die is provided with one inner die arranged between the inner peripheral surface of the plurality of outer dies and the outer peripheral surface of the tubular body in close contact with each other in the thickness direction over the entire circumference. The bulge forming apparatus according to any one of claims 1 to 3, wherein the mold has an opening having a shape corresponding to a convex shape to be formed in the tubular body. Using a metal flat plate as a material, two or more inner dies are provided, which are arranged between the inner peripheral surface of the plurality of outer dies and the outer peripheral surface of the tubular body in close contact with each other in the thickness direction over the entire circumference. The bulge forming apparatus according to any one of claims 1 to 3, wherein at least the innermost inner mold of the two or more inner molds has an opening having a shape corresponding to the convex shape to be formed in the tubular body. .. At least one of a plurality of outer dies which are reciprocally arranged in a direction of approaching and separating from each other along the radial direction of the tubular body in each region obtained by dividing the outer peripheral portion of the tubular body into a plurality of regions along the circumferential direction. Of the inner mold arranged in a part between the inner peripheral surface of the plurality of outer molds and the outer peripheral surface of the pipe body, and the pipe body arranged in the inner mold, using one metal flat plate as a material. Prepare a pressurizing mechanism that pressurizes the inside,
A bulge forming method in which the inside of the tube is pressurized by the pressurizing mechanism in a state where the inner die is sandwiched between the plurality of outer dies and the tube is restrained in the radial direction. A plurality of outer molds that are reciprocally arranged in directions that approach and separate from each other along the radial direction of the pipe body in each region obtained by dividing the outer peripheral portion of the pipe body into a plurality of parts along the circumferential direction.
An inner die arranged on a part between the inner peripheral surface of the plurality of outer molds and the outer peripheral surface of the tubular body using at least one metal flat plate as a material.
Cylindrical urethane inserted into the tube body arranged in the inner mold and divided into a plurality of parts along the axial direction of the tube body, the urethane is the first end portion of the tube body. A pressing member that presses from the side along the axial direction and a pressurizing mechanism including a closing member that closes the second end side of the tubular body are prepared.
The urethane is inserted into the inside of the pipe body, the inner mold is sandwiched by the plurality of outer molds, the pipe body is restrained in the radial direction, and the second end side of the pipe body is closed by the closing member. A bulge forming method in which the inside of the tubular body is pressed by the pressing member by pressing the urethane from the first end side of the tubular body along the axial direction.

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