JPH01205841A - Method for forming bottomed internal tooth profile member - Google Patents

Abstract

PURPOSE:To precisely form the bottomed internal tooth profile member equipped with a thick metal part at the opening part by press-fitting the cuplike preform having a rough tooth on the inner peripheral face and annular escape groove on the hole bottom circumference into the orifice of a die by the mandrel having a tooth profile on the outer peripheral face and an annular projection at the tip. CONSTITUTION:A cuplike preform 3 has cylindrical part 4, rough tooth 5, bottom part 6, annular escape groove 7 and boss. The tooth profile 25 in the length l1 slightly longer than the rough tooth 5 is provided on the outer periphery of the tip of a mandrel 22 and a tapered guide part 26 is formed at its tip. On the mandrel end face the annular projection 27 for forming the escape groove is projected. The cuplike preform 3 is then supported by an orifice 14 by setting it in the large diameter part 13 of a die 12 and a punch holder 16 is descended. The guide part 26 of the mandrel 22 is then brought into contact with the rough tooth 5 of the preform 3, approached by allowing the tooth trace to coincide therewith and the annular projection 27 is seated in the escape groove 7. The preform 3 is then pushed out of the orifice 14, the descent of the punch holder 16 is stopped by leaving the thick metal port edge 10 in the length l2 at the upper end of the cylindrical part 4 and a bottomed internal tooth profile is formed.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a bottomed internal in which a large number of tooth-shaped grooves in the axial direction are formed in the form of serrations on the inner circumferential surface, such as in the case of a viscous coupling. The present invention relates to a method of forming a tooth-shaped member.

(Prior art) A mandrel with several semicircular protrusions on the outer periphery is inserted into the inside of a cup-shaped material, and the material is diced while pressing the inner bottom surface of the material with the end face of the mandrel and extruded backward. A method of forming an outer ring of a constant velocity joint by forming several vertical grooves on the inner surface while doing so is known, for example, as described in Japanese Patent Publication No. 48-4809.

In addition, a mandrel with a large number of teeth on the outer periphery is inserted into the cup-shaped material under pressure with a spring, and the bottom of the material is held between the tip of the mandrel and a punch from the inside and outside, and the punch opens the material. A method of forming an internal tooth profile on the inner surface of the cup by press-fitting it into a die from the side and extruding it forward was proposed by the inventors of the present invention and disclosed in Japanese Patent Application Laid-Open No. 81-269.
Published by 951.

(Problems to be Solved by the Invention) The backward extrusion means used for the constant velocity joint outer ring described above makes it easy to stretch the material rearward, but it is difficult to move it toward the inside of the circumference. Forming is possible when the number of grooves is small and the grooves are loosely connected to the inner circumferential surface, such as on an outer ring, but if the grooves are narrow, such as a tooth profile with a module of 1.0 to 3.0, and the cross-sectional area is small. If the change is rapid, it is not possible to form a precise tooth profile even if rough teeth have been formed in the material in advance.

Furthermore, when using this method, there is a risk that the bottom part of the material may come off due to being pushed by the mandrel, so it is necessary to reduce the amount of molding at one time or make the bottom thicker.

In order to solve these problems, the inventors proposed the method disclosed in Japanese Patent Application Laid-Open No. 81-289951. However, according to this method, only the cylindrical part of the cup with a uniform thickness can be formed. , it is not possible to increase the strength of the open end. When using the cup-shaped tooth profile made by this method as a case for a viscous coupling, for example, it is desirable that the opening be thick for strength reasons and for machining the lid attachment part. No tooth profile on the inner circumferential surface is required. However, it is not possible to mold such a cup using the methods described above.

Therefore, it is an object of the present invention to provide a method for precisely and easily forming an internal tooth profile in which the opening has a thick portion and tooth-shaped serrations are formed on the inner peripheral surface.

(Means for Solving the Problems) The present invention solves the above-mentioned problems by one of the following means. The first means has rough teeth in the axial direction on the inner circumferential surface, and A cup-shaped material with an annular relief groove at the corner is formed by extrusion molding, and a floating-supported mandrel having an annular projection at the tip and an axial tooth profile on the outer circumferential surface is fitted into the cup-shaped material, and the mandrel is attached to the mandrel. The cylindrical upper punch that fits outward is brought into contact with the mouth edge of the cup-shaped material, and the inner surface of the cup-shaped material is restrained by the mandrel while the upper punch is pressurized to insert the cup-shaped material into the orifice of the die from the bottom to the mouth edge. The method is characterized in that the tooth profile on the inner circumferential surface is finished formed by press-fitting and squeezing the inner circumferential surface, and a thick-walled mouth rim is formed at the mouth rim. Supports the punch in a slidable and rotatable manner,
This device has an additional means characterized in that the mandrel is rotated and positioned by guiding the tapered guide portion of the tooth profile end face on the tip side of the mandrel by the end face of the rough teeth of the cup-shaped material.

(Function) In the first means, the cup-shaped material enters the die by pressing the opening edge with the upper punch while the inner surface shape is regulated by the mandrel, and the cup-shaped material enters the die with the bottom, the annular relief groove outer circumference,
The cylindrical part is narrowed in this order, thereby forming an internal tooth profile on the inner peripheral surface, while the opening remains as a thick walled part without being narrowed.

In addition, in the second means, when setting the cup-shaped material in the die, the tapered slope formed on the end surface of the tooth profile of the mandrel is guided by the rough tooth end surface of the material, without performing angular positioning. is automatically rotated and positioned.

(Example) Examples of the present invention will be described below based on the drawings. In Fig. 1, (a) to d) show the rough machining process, and (e
) shows the product after finishing the cup-shaped material of (d). First, a material 1 cut from a round bar is upset into a large-diameter material 2 having a diameter close to the product diameter, and a cup-shaped material 3 shown in (C) is formed by extrusion molding. The material 3 includes a cylindrical portion 4,
It is equipped with rough teeth 5, a bottom part 6, an annular relief groove 7, and a boss 8. In (d), a shaft mounting hole 9 is bored in the boss 8. Then, this cup-shaped material 3 is made into the cup-shaped material 3 as shown in FIG. 1 (
e) Finish to product W. Product W includes a reduced cylindrical portion 4a, a finished tooth profile 5a, and an annular clearance groove 7a.
, thick bottom edge 10. It has a smooth inner peripheral surface 10a.

In FIG. 2, 12 is a die, which has a large diameter portion 13 equal to the outer diameter of the thick-walled mouth edge IO of the product W and an orifice 14 equal to the outer diameter of the cylindrical portion 4a, and is fixed to a die holder 15.

A cylindrical upper bunch 17 is fixed to the punch holder 1B with a fixing member 18. A guide hole 19 and an enlarged diameter portion 20 are formed inside the upper punch 17, a needle bearing 21 is housed therein, and a mandrel 22 is inserted and supported in a floating manner. The flange 23 of the mandrel 22 can be lowered within the enlarged diameter section 20 until it touches the needle bearing 21, and is pressurized from behind by a spring 24.

A tooth profile 25 with a length 11, which is slightly longer than the rough teeth 5, is provided on the outer periphery of the tip of the mandrel 22, and a tapered guide portion 2 is provided at the tip.
6 is formed. The guide portion 2B has a tapered slope shown by an angle α in FIG. 3(a), and a ridgeline 28a along the center line of each tooth in FIG.
8b is provided.

Further, an annular projection 27 for forming an escape groove is provided protruding from the end surface of the mandrel 22.

As shown in FIG. 2(a), the cup-shaped material 3 is set in the large diameter portion 13 of the die 12 and supported by the orifice 14,
When the punch holder 1B is lowered, the guide portion 26 of the tooth profile 25 of the mandrel 22 comes into contact with the end portion 5a of the rough teeth 5 of the material 3, and is guided by the slope 26b and rotates slightly as shown by the arrow A to form the tooth trace. The annular protrusion 27 is seated in the escape groove 7.

When the punch holder 16 is further lowered, the lower end of the upper punch air moves forward while pressurizing the upper end of the cylindrical part 4, as shown in FIG. Push out the cylindrical part 4 in this order. At this time, the mandrel 22 is pressurized by the punch holder 16 via the spring 24, and therefore moves in the direction of arrow B together with the bottom portion 6. Then, the punch holder 1B is stopped from descending, leaving a thick rim 10 with a length of 12 at the upper end of the cylindrical portion 4.

Due to this extrusion, the flesh of the cylindrical portion 4 flows inward due to the squeezing action of the orifice 14 and the pressing force of the upper bunch 17 and is extruded onto the surface of the mandrel 22.
Tooth profile 5a and annular relief groove 7 that accurately transfer the annular protrusion 27
a is formed, and at a position above the tooth profile 25, an inner circumferential surface 10a is formed by transferring the cylindrical surface of the mandrel. Next, the punch holder 16 is raised and the product W is extruded by appropriate knockout.

In these operations, the needle bearing 21 allows the mandrel 22 to easily slide up and down relative to the upper bunch 17 and rotate in the direction of arrow A. It is also possible to guide the rotation.

(Effects of the Invention) As described above, the present invention extrudes the cylindrical part of the material toward the tooth profile of the mandrel by applying pressure from the orifice of the die and the upper punch. The effective length of the tooth profile is ensured by the annular relief groove.
In addition, a thick rim is formed at the opening of the product to reinforce the opening, and a groove for a retaining ring or the like can be provided by cutting to attach the lid.

In addition, the mandrel is in a floating state and moves by following the movement of the product due to the spring, and does not require any special operating device, which simplifies the construction.

Since the mandrel is automatically positioned along the tooth trace of the rough teeth by the tooth-shaped guide section, no positioning means is required for setting the materials.

[Brief explanation of the drawing]

Figures 1 (a) to (e) are cross-sectional views of the workpiece in the process order of the present invention, Figures 2 (a), (b), and (C) are cross-sectional views showing the final forming process, and Figures 3 (a) (b). ) is a vertical sectional view and an end view of a portion of the tip of the mandrel. 3...Cup-shaped material 5...Rough teeth 5a...
・Tooth profile 7.7a...Annular relief groove lO
...Thick wall rim 12...Die 14...
・Orifice 22...Mandrel 25・
...Tooth profile 2B...Guide part 27...
・Annular protrusion Figure 1 (a) (c) (d)

Claims (1)

[Claims] 1. A cup-shaped material having rough teeth in the axial direction on the inner circumferential surface and an annular relief groove on the circumferential corner of the bottom of the hole is formed by extrusion molding, and an annular projection on the tip and a shaft on the outer circumferential surface. A floatingly supported mandrel having a tooth profile in the direction is fitted into the cup-shaped material, and a cylindrical upper punch fitted externally on the mandrel is brought into contact with the mouth edge of the cup-shaped material, and the inner surface of the cup-shaped material is Pressure is applied to the upper punch while restrained by the mandrel, and the cup-shaped material is press-fitted into the orifice of the die from the bottom to near the mouth edge and squeezed, finishing the tooth profile on the inner circumferential surface and forming a thick-walled mouth edge on the mouth edge. A method for forming an internal tooth profile member with a bottom. 2. Support the mandrel in a slidable and rotatable manner relative to the upper punch, and rotate the mandrel by guiding the tapered guide portion of the tooth-shaped end face on the tip side of the mandrel with the end face of the rough teeth of the cup-shaped material. 2. The method for molding a bottomed internal tooth profile member according to claim 1, wherein the bottomed internal tooth profile member is positioned.