JP2002035882A - Forming method of circular member with collar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forming method preventing cracks from arising at the outer diametral part of a collar formed by upsetting. SOLUTION: In the method in which the end face 2 of a hollow member 1 is upset to form a collar 3A or the like at the end of the follow member, the outer diametral side end face 2B of the hollow member is formed to come into contact with the end face of a die subjected to upsetting earlier than the other part in the beginning time of upsetting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a flanged annular member, and more particularly, to a method for forming a flanged annular member in which an end of a hollow member is formed by upsetting.

[0002]

2. Description of the Related Art JP-A-10-202339 discloses that
First, an end of a cylindrical material is pressed to open at least one end, and a preformed product having a thickness of the opening substantially equal to the thickness of a desired flange is formed. A method in which the thickness of one end opening of a product is maintained, and the opening is bent to form a flange whose diameter gradually increases toward the end, that is, a part of a cylinder opened at one end is bent outward. There is disclosed a method of forming a flanged housing in which a flange having a shape having a larger inner and outer diameter and a lower height than an annular member before processing is formed.

[0003] Further, as shown in FIG.
Is installed by the method shown in FIG. 5 by setting the hollow member 11 having an angle close to a right angle to the inner and outer diameter surfaces 12C and 12F.
A method of forming the flange 13A at the end of the hollow member 13 is also conceivable. This molding method is a method often used for a general forging material having sufficient ductility.In this method, a hollow member is inserted into a die by a punch, and further advanced punches, and one end of the hollow member by a die and a knockout pin. It is upset to form a flange and the like.

[0004]

However, Japanese Patent Application Laid-Open Publication No.
According to this method disclosed in Japanese Patent Publication No. 0-202339, it is possible to form a sound flange portion with a material having sufficient ductility, such as a material having a relatively small carbon content,
In the case of materials with low ductility such as bearing steel with a high carbon content, circumferential tensile stress acts on the inside of the material as the inner and outer diameters increase, and the ductility limit of the material may be low. Cracks are likely to occur on the outer diameter surface. For this reason, when using a material with low ductility as a material, it is difficult to obtain a sound product.

The hollow member 11 shown in FIG.
As shown in FIG. 5, the end face 12 and the inner diameter face 12C are connected to the end of the hollow member 13 by a curved surface by setting up with a die made of a punch A and a die D made of an inner diameter holding pin B and a sleeve C. In the method of forming the flange portion 13A having the shape shown in FIG. 4B, the corner 12D between the end surface 12 of the hollow member 11 and the inner diameter surface 12C has an inner diameter holding portion formed according to the shape to be formed. Sliding according to the shape of the pin B, the inner and outer diameters of the hollow member 11 are widened.

[0006] By the above upsetting process, the end surface 12 of the hollow member 11 is warped in a direction opposite to the center axis of the hollow member 11. As a result, when the punch A further moves forward, FIG.
As shown in (a), the contact between the end face 12 of the hollow member 11 and the end face C ′ of the sleeve C becomes a part of the end face 12 of the hollow member 11. More specifically, a contact portion between the end face C ′ of the sleeve C and the end face 12 is an inner end face, that is, the hollow member 1.
Only the corner 12D between the end surface 12 and the inner diameter surface 12C of the sleeve C does not come into contact with the end surface C 'of the sleeve C.

[0007] Even immediately before the end of machining, FIG.
(B) As shown in FIG.
Is not constrained by a die such as the punch A and the die B at all. Therefore, in the hollow member 11 made of a material with low ductility such as bearing steel, the end face outer diameter side 12
A tensile stress acts on E, and a crack occurs in the outer diameter of the upset portion. Therefore, there is a problem that it is difficult to obtain a healthy product.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. In forming a flanged annular member from a hollow member made of a material having low ductility such as bearing steel, An object of the present invention is to provide a method of forming a flanged annular member that prevents occurrence of an outer diameter crack of a flange formed by swaging.

[0009]

In order to achieve the above object, a method of forming a flanged annular member according to the present invention comprises the steps of swaging an end surface of a hollow member made of a material having low ductility such as bearing steel, In the method of forming a flange or the like in which an end surface and an inner diameter surface are connected by a flat surface or a curved surface to the end of the hollow member, the outer end surface of the hollow member is earlier than other parts in the initial stage of upsetting. It has a shape that comes into contact with the end face of the mold to be upset.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a method of forming a flanged annular member by upsetting from a hollow member made of a material having low ductility such as bearing steel. The present invention proposes a molding method for preventing an outer diameter crack of an upset portion which is likely to be generated because a tensile stress is applied, and the main point is that the shape of the hollow member before the upsetting is provided for the upsetting. The punch and the outer surface of the end face of the hollow member to be machined are shaped so that they contact each other at the beginning of the upsetting operation. To progress.

By employing the upsetting method as described above, the end face of the die such as a punch and the outer diameter of the end face of the hollow member come into contact immediately after the start of upsetting. At this time, a frictional force is generated in a radial direction on a contact surface between a die such as a punch and an end surface of the hollow member, and expansion deformation to the outside of the end surface outer diameter portion is restrained. Circumferential tensile stress, which is a major cause of crack generation, is greatly reduced.

Also, during the upsetting process, the outer diameter of the end face is constantly in contact with a mold such as a punch, and compressive stress and frictional resistance act on this part, whereby the tensile stress in the circumferential direction at the outer diameter of the end face is reduced. It is possible to obtain a sound product that is relaxed and has no crack in the outer diameter of the upsetting portion. The maximum effect can be obtained by appropriately determining the shape and size of the inclined surface and the like according to the required shape and size of the product.

Hereinafter, the method of the present invention will be described in detail with reference to FIGS. 1 to 3. First, a hollow member 1 shown in FIG. 1A is formed from a bearing steel by cold forging or other methods.
The end face 2 of the hollow member 1 has a substantially horizontal end face 2A on the inner diameter side where no upsetting is performed, and the outer end face 2B on the outer diameter side on which the upsetting is performed is inclined upwardly outward. The surface is formed. The essential point of the method of the present invention is that a hollow member having an end surface 2B on the end surface 2 of the hollow member 1 whose outer diameter side end surface 2B comes into contact with a mold at the beginning of upsetting described later is used. .

The hollow member 1 is conveyed to the entrance of a die D shown in FIG.
It is supplied into the die D by pushing in with A). Here, the punch A includes an inner diameter holding pin B and a sleeve C, and the inner diameter holding pin B is manufactured according to a shape to be formed. Supply of the hollow member 1 into the die D by the punch A is performed by inserting the distal end of the inner diameter holding pin B into the hollow member 1 at the time of starting the upsetting shown in the left half of FIG. Set to state.

After the hollow member 1 is supplied into the die D, the punch A further advances, and first, the corner of the inner end surface 2A of the hollow member 1, that is, the end surface 2 of the hollow member 1 and the inner surface 2C are formed. Corner 2D contacts the inner diameter holding pin B.
Then, as the punch A advances, the corner 2D
Moves outward while sliding along the shape of the inner diameter holding pin B.

Further, the punch A advances, and the corner 2D
Reaches the end face B 'of the inner diameter holding pin B, the end face 2 of the hollow member 1 warps. However, as described above, the end face 2B on the outer diameter side of the hollow member 1 is formed by an inclined surface rising outward. 3A, the outer end surface 2B of the hollow member 1 is connected to the end surface C 'of the sleeve C earlier than the inner end surface 2A, as shown in the initial stage of the upsetting process in FIG. Contact is made and this state is maintained.

Then, the punch A further advances, and FIG.
As shown in the figure immediately after the start of the upsetting process of (b), the outer end surface 2B and the inner end surface 2A of the hollow member 1 come into contact with the end surface C ′ of the sleeve C, respectively.
As shown in the figure immediately before the end of the upsetting process of (c), the punch A moves forward until the end face of the punch A and the entire end face 2 of the hollow member 1 come into contact.

As a result, a frictional force is generated in the radial direction at the contact surface between the die A such as the punch A and the die D and the end face 2 of the hollow member 1, and the outward deformation of the end face outer diameter portion 2E is restricted. By doing so, the tensile stress in the circumferential direction, which is a major cause of the occurrence of cracks on the outer diameter side of the end face outer diameter portion 2E, is greatly reduced. Also, during the upsetting process, the end face outer diameter portion 2E constantly contacts a mold such as the punch A, and compressive stress and frictional resistance act on this portion. Thereby, the tensile stress in the circumferential direction at the end face outer diameter portion 2E is relaxed, and it is possible to obtain a sound product with no crack in the outer diameter of the upset portion.

The punch A is further advanced, and as shown in the figure at the end of the upsetting process in the right half of FIG. 2, the hollow member 1 is swaged up to a required size, and the flange shown in FIG. Part 3A
The flanged annular member 3 provided with Thereafter, the punch A starts retreating, and the upsetting process ends. Then, the collared annular member 3 which has been swaged into a product in the die D is discharged out of the die D by a kick-out pin E which has been previously incorporated into the die D of the mold.

[0020]

The method for forming a flanged annular member according to the present invention has the above-described structure. Therefore, the flanged annular member is formed by upsetting from a hollow member made of a material having low ductility such as bearing steel. Even in this case, there is an effect that a crack is not generated in the outer diameter portion of the upset portion, and a healthy product can be manufactured with a high yield.

[Brief description of the drawings]

FIG. 1 is a front view (a) of a half-section of a hollow part used in the method of the present invention and a front view (b) of a half-section of a product.

FIG. 2 is a longitudinal sectional view at the start of upsetting by a mold (left half) and at the end of upsetting (right half).

FIGS. 3A and 3B are partially enlarged sectional views of an initial stage of the upsetting process (A), immediately after the start of the upsetting process (B), and immediately before the end of the upsetting process (C).

FIG. 4 is a front view (a) of a half part of a hollow part provided for a conventional processing method, and a front view (b) of a half part of a product.

FIG. 5 is a vertical cross-sectional view of a conventional method using a mold at the start of upsetting (left half) and at the end of upsetting (right half).

FIG. 6 is a partially enlarged cross-sectional view of the conventional method immediately after the start of the upsetting (A) and immediately before the end of the upsetting (B).

[Explanation of symbols]

 Reference Signs List 1 hollow cylindrical member 2 end face 2A inner end face 2B outer end face 2C inner diameter face 2D corner 2E end outer diameter section 3 flanged annular member 3A flange A punch B inner diameter holding pin B 'same end face C sleeve C' Same end face

Claims (4)

[Claims] 1. An end surface of a hollow member made of a material having low ductility such as bearing steel is swaged, and a flange or the like having an end surface and an inner diameter surface connected by a flat surface or a curved surface is formed at the end of the hollow member. The method of forming a flanged annular member, wherein the hollow member has a shape in which an end surface on an outer diameter side of the hollow member comes into contact with an end surface of a mold provided for upsetting earlier than other portions at the beginning of upsetting. Method. 2. The method for forming an annular member with a flange according to claim 1, wherein the end surface on the outer diameter side of the hollow member is a hollow member configured to protrude upward from the end surface on the inner diameter side. 3. The method of forming a flanged annular member according to claim 1, wherein the end surface of the hollow member is a hollow member having an inclined surface gradually rising from an inner diameter side to an outer diameter side. . 4. The hollow member according to claim 1, wherein the end surface of the hollow member is a hollow member having a substantially horizontal surface on an inner diameter side and an inclined surface whose outer diameter side gradually rises outward. A method for forming a flanged annular member.