JP2581173B2 - Cold forging method of internal spline with tooth chamfer - Google Patents

Description

The present invention relates to a method for cold forging of an internal spline having a sharp edged tooth chamfer, and relates to a sleeve for a gear clutch of a gear transmission of an automobile or the like. And the like, which is used for machining an inner spline having a sharp edged tooth chamfer on the spline end face.

(Prior Art) As a prior art relating to the present invention, there is JP-A-51-30559.

In the cold forging method of the inner spline shown in FIG. 7, the molding washer 17 and the blank are pressed into a die 13 having a tooth profile while being clamped by a punch 16 and a knockout 18, so that the spline shaft is extruded at the same time. This is a cold forging method that forms a chamfer and can omit a tooth chamfering step by cutting or the like.

(Problems to be Solved by the Invention) However, the above-mentioned processing method requires one molded washer 17 which is not originally a product per product, which leads to an increase in cost, and furthermore, utilizing the deformation of the molded washer. Since the chamfering is performed, the chamfering shape becomes an R shape, and there is a problem that the chamfering of a sharp ridgeline required for spline chamfering used for a gear clutch or the like cannot be formed.

In the cold forging method for the inner spline of the present invention, a method for cold forging an inner spline capable of forming a sharp beveled chamfer at the same time as forming the inner spline-in without using a washer or the like is described. It is an issue.

[Configuration of the invention]

(Means for Solving the Problems) The technical means taken to solve the above technical problems are as follows. That is, in the cold forging method of forming a sharp ridge tooth chamfer on one end face of the inner spline at the same time as the inner spline, a spline extrusion is provided at the position where the spline forming of the spline extrusion die is completed, and a chamfer forming portion is provided following the spline. The knockout sleeve was placed at a position where the extruded material hit the upper surface while keeping concentric with the mold,
This is a simultaneous cold forging method of inner spline and tooth chamfering.

(Operation) By pressing the blank against the tooth forming portion of the die and the mandrel, the material flows into the gap portion of the mandrel to form a spline.

Thereafter, when the punch further descends, the material flows along the chamfered molding portion arranged so as to coincide with the center of the gap portion of the mandrel, and the chamfered shape is formed at the tip of the spline.

As the punch further descends, the material of the blank is axially controlled at the tip of the knockout sleeve, and flows toward the chamfer forming section, thereby forming a sharp ridge chamfer.

Example An example will be described below.

FIG. 1 shows a configuration of a cold forging die for simultaneously forming an inner spline and a tooth chamfer. 1 is a blank formed into a cylindrical shape by a method such as cold forging, and 2 is a cylindrical portion 2a on the upper portion serving as a guide for the blank. A mandrel having a tooth shape 2b and a chamfered shape portion 2c corresponding to a spline and a chamfer to be formed in the center, 3 is a die, 4 is a knockout sleeve arranged by fitting the mandrel 2 and 5 is an upper part of the mandrel 2. Outer diameter and die 3
A punch having an inner diameter and an outer diameter that can slide with respect to the upper inner diameter of the upper part, and is attached to a press ram (not shown) and can move up and down.

6, 7, and 8 are spacers for supporting the mandrel 2 and the die 3 while maintaining concentricity, and 9 is a knockout sleeve 4.
Knockout pin for taking out the product via

 The operation of the above configuration will be described.

By pressing the blank 1 shown in FIG. 2 against the die 2 and the tooth forming portion 2b of the mandrel 2, the material flows into the void 2d of the mandrel 2 shown in FIG. 5, and is extruded into the cross-sectional shape shown in FIG. An inner spline is formed.

By further lowering the punch 5, the mandrel 2
Flows along the chamfered forming portion 2c arranged so as to coincide with the center of the void portion, and the chamfered shape is almost formed at the tip of the spline.
As shown in FIG. When the punch 5 is further lowered, the material of the blank 1 is controlled at the tip end of the knockout sleeve 4 in the axial direction, flows toward the gap 1e of the chamfered ridge portion, and a sharp ridged chamfer is formed.
In this manner, the spline 1b and the chamfer 1a having a sharp ridge shown in FIG. 6 are formed by only one downward movement of the punch 5, the punch 5 is retracted, the knockout pin 9 is raised, and the molded product 1 is taken out. This completes the molding. With the above method, the inner spline and the sharp ridge are chamfered at the same time.

〔The invention's effect〕

 The present invention has the following effects.

Compared with the prior art, sharp ridges can be chamfered, and the extrusion die is provided with a spline molding part and a tooth chamfer molding part continuously. No unnecessary parts are required, and the chamfering step by machining or the like can be omitted.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of this embodiment, FIG. 2 is a cross-sectional view of a blank before molding, FIG. 3 (A) is a cross-sectional view of a blank during molding, and (B) is A to A of (A). FIG. 4 is a partially enlarged sectional view showing the relationship between the mold and the blank immediately before the completion of molding, FIG. 5A is a side view of the mandrel, and FIG. FIG. 6A is a cross-sectional view of the blank after completion of molding, FIG. 6B is a plan view of FIG. 6A, and FIG. 7 is a cross-sectional explanatory view of a conventional example. 1 ... blank, 2 ... mandrel, 3 ... die, 4 ... knockout sleeve, 5 ... punch.

Claims (1)

(57) [Claims] In a cold forging method for forming a chamfer with a sharp ridge on one end face of an inner spline at the same time as an inner spline, a chamfer forming portion is provided following a spline at a position where spline forming of a spline extrusion die is completed. A simultaneous cold forging method of inner spline and tooth chamfering, in which a knockout sleeve is arranged at a position where the extruded material hits the upper surface while keeping concentricity with the spline extrusion die.