JP2018051622A - Bulge forming device and bulge forming method - Google Patents

Abstract

[PROBLEMS] To simplify the production work of a mold, prevent wear of the mold, and realize cost reduction.
A mold of a bulge forming apparatus 10 for forming a convex shape on a peripheral surface of a tube body 20 is constituted by an outer mold 3, a first plate material 4, and a second plate material 5. The first plate member 4 and the second plate member 5 are sandwiched over the entire surface between the inner peripheral surface of the outer mold 3 that restrains the tube body 20 in the radial direction and the tube body 20. An opening having a shape corresponding to the convex shape to be formed on the peripheral surface of the tubular body 20 was formed in the second plate member 5 located on the inner side. By pressing the urethane rubber 6 from above with the plunger 7, the urethane rubber 6 presses the inner peripheral surface of the tube body 20 toward the outside, and the portion facing the opening 51 on the peripheral surface of the tube body 20 is convex. Transforms into
[Selection] Figure 3

Description

  The present invention relates to a bulge forming apparatus and a bulge forming method for deforming a peripheral surface of a tubular body into a convex shape carved into the mold by pressurizing the inside of the tubular 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 conventional urethane bulge molding, a tubular body is housed in a mold having a predetermined concave shape engraved on the inner surface, urethane rubber is inserted into the tubular body, and then the urethane rubber is expanded to mold the tubular body. Pressing against the mold, the peripheral surface of the tube is deformed into a convex shape so as to follow the concave shape carved into 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 machine. Moreover, the metal mold | die is divided | segmented into plurality in the surface orthogonal to the axial direction of a pipe body in consideration of accommodation and taking-out of a pipe body.

JP 2005-313187 A

  However, in the conventional bulge molding, since the electric discharge machining and the cutting work are used for the engraving of the concave shape on the inner surface of the mold, the production work of the mold takes a long time. In addition, when the mold is divided into a large number in order to increase the roundness of the molded pipe body, the concave shape corresponding to the 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, it is necessary to produce a plurality of molds with high dimensional accuracy so that the joint between adjacent molds does not appear in the design of the tube. Furthermore, if the concave shape is worn by repeated molding operations, it may be necessary to replace the entire mold. These increase the cost of bulge forming.

Such a problem occurs not only in urethane bulge molding using urethane rubber, but also in all bulge molding including hydroforming using a low-compressible or incompressible fluid whose volume change at the time of deformation is small.

  An object of the present invention is to form a mold with an inner mold of a plate member interposed between an outer surface of a tubular body in which a convex shape is formed and inner surfaces of a plurality of outer molds that restrain the tubular body in a radial direction. Accordingly, an object of the present invention is to provide a bulge forming apparatus and a bulge forming method that can simplify the mold manufacturing operation, prevent the mold from being worn, and realize a reduction in cost.

  The bulge forming apparatus according to the present invention includes a plurality of outer dies, inner dies, and a pressure mechanism. The plurality of outer molds are reciprocally arranged in directions close to and away from each other along the radial direction of the tube body in respective regions obtained by dividing the outer peripheral portion of the tube body into a plurality of portions along the circumferential direction. The inner mold is disposed between the inner peripheral surface of the outer mold and the outer peripheral surface of the tubular body using at least one metal flat plate as a material. The outer mold restrains the tube body in the radial direction with the inner mold interposed therebetween. The pressurizing mechanism pressurizes the inside of the tube disposed in the inner mold.

  The bulge forming method according to the present invention is a plurality of reciprocating arrangements in a direction in which the outer peripheral portion of the tubular body is divided into a plurality along the circumferential direction so as to approach and separate from each other along the radial direction of the tubular body. An outer mold, an inner mold disposed at a part between the inner peripheral surface of the outer mold and the outer peripheral surface of the tubular body, and a tubular body disposed in the inner mold, using at least one metal flat plate as a raw material A pressurizing mechanism for pressurizing the inside of the tube body, and pressurizing the inside of the tube body by the pressurizing mechanism in a state where the inner mold is interposed in a part between the tube body and the outer mold.

When the inside of the tube body is pressurized by the pressurizing mechanism with the inner mold partly interposed between the tube body and the outer mold, the portion where the inner mold does not exist on the outer peripheral surface of the tube body expands outward. And 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 tubular body is easily formed.

  In this configuration, the pressurizing mechanism includes a pressurizing member made of a low-compressible or incompressible fluid or flexible material with a small volume change at the time of deformation, and a pressing member that presses the pressurizing member in the axial direction of the tubular body. And a closing member that closes the first end portion in the axial direction of the tube body.

  After inserting the pressure member from the second end into the tube whose first end is closed by the closing member, the pressure member is pressed in the axial direction of the tube by the pressing member. The inside 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 tube can be easily manufactured at a low cost, the outer mold can be prevented from being worn, and the replacement work when the inner mold is worn becomes easy.

  Using a metal flat plate as a raw material, it has two or more inner molds arranged in close contact with each other in the thickness direction over the entire circumference between the inner peripheral surface of a plurality of outer molds and the outer peripheral surface of the tubular 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 in the tubular body.

  By forming openings in two or more inner dies, a step-like convex shape can be formed on the peripheral surface of the tubular body. Further, by not forming an opening in the outermost inner mold among the two or more inner molds, the outer peripheral surface of the tubular body deformed by the pressurization of the pressurizing member does not directly contact the outer mold. No wear on the outer mold.

  According to the present invention, it is possible to simplify the production work of the mold, prevent the mold from being worn, and reduce the cost.

It is sectional drawing of the bulge forming apparatus which concerns on embodiment of this invention. (A) And (B) is an external view of the 2nd board | plate material of the same bulge forming apparatus, and an external view of the tubular body shape | molded with the same bulge forming apparatus. (A)-(C) are sectional drawings which show the bulge forming method which concerns on embodiment of this invention. It is an external view of the 1st and 2nd board | plate material of the bulge forming apparatus which concerns on another embodiment of this invention. (A) And (B) is an external view of the 2nd board | plate material of the bulge forming apparatus which concerns on another embodiment of this invention. It is sectional drawing which shows the deformation | transformation state of the pressurization member using integral type urethane in the bulge shaping | molding apparatus which concerns on embodiment of this invention. It is sectional drawing which shows the deformation | transformation state of the pressurization member using division type urethane in the bulge shaping | molding apparatus which concerns on embodiment of this invention.

  Hereinafter, a bulge forming apparatus and a bulge forming method according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a bulge forming apparatus 10 according to an embodiment of the present invention includes a base 1, a drive member 2, an outer mold 3, a first plate member 4, a second plate member 5, a urethane rubber 6, 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 molding.

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

The lower end portion of the shaft portion 73 of the plunger 7 passes through the hole portion 13 from above. The fixing screw 15 is screwed into the lower end surface of the shaft portion 73 exposed below the hole portion 13 through the 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 2nd convex part 12 is an obstruction | occlusion member of this invention, has an outer diameter equal to the internal diameter of the tubular body 20, and the lower end part which is the 2nd end part of the tubular body 20 is externally fitted, and is obstruct | occluded. .

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

  The outer mold 3 is composed of a total of four pieces each positioned in a region equally divided into four parts, for example, the outer peripheral portion of the tubular body 20. The outer peripheral surface of each outer mold 3 is formed in the same truncated cone 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 tube body 20. Each outer die 3 is in contact with the upper surface of the base 1 at the bottom, and can be reciprocated only in the radial direction of the tube body 20 via a key (not shown). Further, a step portion 31 into which the first convex portion 11 is fitted is formed at the bottom of each outer mold 3.

  The outer dies 3 are urged in directions away from each other by an elastic force of an elastic member (not shown) disposed between the outer dies 3 as an example. 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 truncated cone shape as the inner peripheral surface of the driving member 2, each outer mold 3 moves along the radial direction of the tubular body 20 when the driving member 2 is lowered. When the drive members 2 are moved up so as to approach each other, the outer molds 3 move away from each other along the radial direction of the tube body 20.

  In addition, the drive member 2 may drive each of the four outer mold | types 3 separately. In addition, the driving member 2 can also be formed with a flat inclined surface on the inner side surface. In this case, the outer side surface of each outer mold 3 is a flat inclined surface that always abuts against the inner side surface of the driving member 2. Form. Furthermore, the drive member 2 may be configured as a plurality of members positioned in a region obtained by equally dividing the outer peripheral portion of the tube body 20 into a plurality of parts, and may be configured to move in the radial direction of the tube body 20.

  The first plate member 4 and the second plate member 5 correspond to the inner molds of the present invention, respectively. For example, a metal flat plate made of SUS304 having a plate thickness of 1 mm is bent into a cylindrical shape. The 1st board | plate material 4 and the 2nd board | plate material 5 are inserted in the inside of the outer type | mold 3 in the state piled up with the 1st board | plate material 4 outside. As an example, the first plate member 4 has the entire outer surface opposed to the inner peripheral surface of the outer mold 3. The 2nd board | plate material 5 is equipped with the opening part 51 as shown in FIG. 2 (A) 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.

  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 member 4 and the second plate member 5 to the outer diameter of the tube body 20. Each of the 1st board | plate material 4 and the 2nd board | plate material 5 does not necessarily need to be comprised with one metal flat plate. It can also be divided into a plurality along the circumferential direction of the tube body 20.

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

  The plunger 7 is a pressing member according to the present invention, and is configured by concentrically arranging a head portion 71, a disc 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 a screw hole exposed at the lower end surface. The 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 is provided with a shaft portion 73 whose upper limit position is positioned by the washer 16 in order to hold the urethane rubber 6 with certainty. However, it is necessary that the displacement of the urethane rubber 6 can be reliably regulated during the urethane bulge processing. In addition, the shaft portion 73 can be omitted.

  The ring 8 has an annular shape and is fitted into a 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 tube body 20 by contact with the ring 8 at the upper part and contact with the first convex part 11 at the lower part. The ring 8 can 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 using a bulge forming apparatus 10. First, the outer member 3 is separated from each other by positioning the driving member 2 upward. At this time, the 1st board | plate material 4 and the 2nd board | plate material 5 are accommodated in the inside of each outer type | mold 3 in the state piled up with the 1st board | plate material 4 outside (FIG. 3 (A)).

  Next, the tubular body 20 in which the urethane rubber 6 is inserted is inserted into the second plate member 5 (FIG. 3B). The shaft portion 73 of the plunger 7 passes through 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 tube body 20 is pressed inward along the radial direction via the first plate member 4 and the second plate member 5, and the tube The body 20 is restrained in the radial direction. Thereafter, the plunger 7 is lowered via the head 71, and the upper end, which is the first end of the urethane rubber 6, is pressed along the axial direction from above via the disk 72 (FIG. 3C). ). Since the urethane rubber 6 is a low-compressible flexible material, the inner peripheral surface of the tubular body 20 is pressed outward.

  When the opening 51 is formed in the second plate member 5, the portion of the peripheral surface of the tubular body 20 that faces the opening 51 has the position where the first plate member 4 contacts the inner surface as the maximum position. The other part passes through the inside 51, and the other part is formed into a perfect circle by contact with the inner side surface of the second plate member 5. Thereby, 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, an opening 41 smaller than the opening 51 is formed in a portion facing the opening 51 in the first plate member 4, so that the opening 51 and the opening on the peripheral surface of the tubular body 20. A two-stage convex shape according to the shape of 41 can be formed.

  In the case of 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. Not only does the cost increase, but the repeated deformation of the bulge causes deformation due to wear in the concave shape, which requires periodic die replacement. On the other hand, in the bulge forming apparatus and 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.

  In addition, the inner mold | type of this invention is not restricted to what is comprised with the two metal flat plates of the 1st board | plate material 4 and the 2nd board | plate material 5, but can also be comprised with three or more metal flat plates. In this case, when the bulge processing is repeated by interposing the entire surface between the outer peripheral surface of the tubular body 20 and the inner peripheral surface of the outer mold 3 without forming an opening in the outermost plate material. In addition, the outer mold 3 is not worn by contact with the tubular body 20, and the outer mold 3 need not be replaced.

  In addition, when bulging is used to form the tubular body 20 into a highly round cylindrical shape, only one plate member having no opening is used, so that the outer wall can be removed even when bulging is repeated. The mold 3 is not worn due to contact with the tubular body 20, and the outer mold 3 need not be replaced.

  The first plate member 4 and the second plate member 5 do not necessarily have to be disposed over the entire circumference between the outer peripheral surface of the tubular body 20 and the inner peripheral surface of the outer mold 3. For example, when a convex shape is formed on the circumferential surface of the tubular body 20 over the entire length in the axial direction, at least a part of the circumferential direction of the second plate member 5 extends over the entire length in the axial direction as shown in FIG. It becomes unnecessary. When a convex shape is formed over the entire circumference in a part of the circumferential surface of the tubular body 20, as shown in FIG. 5B, at least a part of the second plate member 5 in the axial direction is entirely formed. It becomes unnecessary over the circumference, and the second plate member 5 is constituted by two metal flat plates arranged vertically with a gap in the middle portion in the axial direction.

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

  If there is a large difference in the radial pressing force acting on the inner peripheral surface of the tube body 20 in the axial direction of the tube body 20, the inner peripheral surface of the tube body 20 is moved in the radial direction at a position facing the upper and lower ends of the opening 51. Cannot be sufficiently pressed toward the outside of the tube, and the convex end to be formed on the outer peripheral surface of the tubular body 20 is blunted. The blunting of the end of the convex shape is not a big problem when the concave portion is formed in the outer mold 3 and the deep convex shape is formed on the outer peripheral surface of the tube body 20, but the plate material 5 on which the opening 51 is formed. When a thin convex shape is formed on the outer peripheral surface of the tubular body 20 using the (including the plate member 4 in which the opening 41 is formed), it becomes a serious problem as deterioration of the finish. This problem is particularly noticeable 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, as an example, urethane rubber 61 divided into six parts along the axial direction of the tube body 20, so that when the plunger 7 is pressed in the axial direction, It has been found that the expansion of the urethane rubber 61 in the radial direction can be made substantially constant between the central portion in the axial direction and the upper and lower ends. With this configuration, the radial pressing force acting on the inner peripheral surface of the tubular body 20 is substantially uniform over the entire axial direction of the tubular body 20, and the plate material 5 (the plate material on which the opening portion 41 is formed) in which the opening portion 51 is formed. 4), 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 the conditions such as the hardness of the material to be used, the material and thickness of the tubular body 20, and the convex shape to be formed on the outer peripheral surface of the tubular body 20. Further, the urethane rubber 61 can partially change its hardness. For example, the corners can be prevented from being damaged by making the hardness of the portions located at the upper and lower ends higher than the other portions.

  The above description of the embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  For example, the urethane rubber 6 is used in the above embodiment as a pressurizing member constituting the pressurizing mechanism of the present invention. However, incompressibility or low compressibility generally used for bulge processing including hydroforming. Other fluids or soft materials can be used as well.

1-base 2-drive member 3-outer mold 4-first plate (inner mold)
5-second plate (inner mold)
6-urethane rubber (pressure member)
7-plunger (pressing member)
10-bulge forming device 12-second convex part (occlusion member)
20-Tube

Claims (7)

A plurality of outer molds that are arranged so as to reciprocate in a direction 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 along the circumferential direction;
Using at least one metal flat plate as a material, an inner mold disposed between an inner peripheral surface of the plurality of outer molds and an outer peripheral surface of the tubular body,
A pressurizing mechanism for pressurizing the inside of the tubular body disposed in the inner mold;
And the plurality of outer dies are bulge forming devices that restrain the tubular body in the radial direction with the inner dies interposed therebetween.   The pressurizing mechanism includes a low-compressible fluid or flexible material pressurizing member inserted into the tube body, and the pressurizing member along the axial direction from the first end side of the tube body. The bulge forming apparatus according to claim 1, comprising: a pressing member that presses and a closing member that closes the second end portion in the axial direction of the tubular body.   3. The bulge forming apparatus according to claim 2, wherein the pressurizing member is a urethane rubber having a cylindrical shape inserted into the tubular body and divided into a plurality of portions along the axial direction.   Using the metal flat plate as a raw material, the inner mold includes one inner mold disposed in close contact with the outer circumferential surface of the plurality of outer molds 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 raw material, comprising two or more inner molds arranged in close contact with each other in the thickness direction over the entire circumference between the inner circumferential surface of the plurality of outer molds and the outer circumferential surface of the tubular body, The bulge forming apparatus according to any one of claims 1 to 3, wherein an inner mold located at least on the innermost side of the two or more inner molds has an opening having a shape corresponding to a convex shape to be formed in the tubular body. . A plurality of outer molds that are arranged to reciprocate in a direction 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 along the circumferential direction; An inner mold disposed in a part between the inner peripheral surface of the plurality of outer molds and the outer peripheral surface of the tubular body, using the metal flat plate as a material, and the tubular body disposed in the inner mold A pressure mechanism for pressurizing the inside, and
A bulge forming method in which the inner side of the tubular body is pressurized by the pressurizing mechanism in a state in which the tubular body is restrained in the radial direction with the inner mold interposed between the plurality of outer molds. A plurality of outer molds that are arranged to reciprocate in a direction 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 parts along the circumferential direction;
Using at least one metal flat plate as a material, an inner mold disposed at a part between the inner peripheral surface of the plurality of outer molds and the outer peripheral surface of the tubular body,
A cylindrical urethane that is inserted into the tubular body disposed in the inner mold and divided into a plurality of pieces along the axial direction of the tubular body, the urethane being a first end of the tubular body A pressing member that presses along the axial direction from the side, and a pressurizing mechanism that includes a closing member that closes the second end side of the tubular body,
The urethane is inserted into the tubular body, the tubular body is restrained in a radial direction by sandwiching the inner mold by the plurality of outer molds, and the second end side of the tubular body is closed by the closing member. And a bulge forming method in which the inside of the tubular body is pressurized by pressing the urethane along the axial direction from the first end side of the tubular body by the pressing member.

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