JP2526579B2 - Forging die for spline shaft forming - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a forging die for a spline shaft or a gear shaft, and is used for molding other spline shafts or gear shafts for automobiles. It is a thing.

(Prior Art) As a prior art according to the present invention, as shown in FIG.
The land portion L of the mold 12 having the spline 11 has a simple linear shape having a constant inner diameter.

(Problems to be solved by the invention) However, the product 13 molded using the mold 12 is the eighth
As shown in the enlarged view (c) of the drawing, the spline is extruded to the large diameter portion and the tooth surface of the spline tip portion 14 and the rear end portion 15.
There is a problem that 14a and 15a occur.

When a rotary shaft spline used for an automobile transmission is manufactured by conventional technology, a 0.4 mm sag occurs at the extruded tip and a 0.2 mm sag occurs at the rear end. Modifications such as working and cold ironing are required, which increases the manufacturing cost.

The present invention is a forging die for a spline shaft or a gear shaft, and a technical object is a forging die for a spline shaft or a gear shaft in which no sagging occurs at the extruded front end portion and the rear end portion of a manufactured product. .

[Structure of Invention]

(Means for Solving the Problems) The technical measures taken to solve the above technical problems are as follows. That is, by extrusion molding, it is a forging die for spline shaft forming that forms a spline on the outer periphery of a solid or hollow cylindrical material, including a land portion for forming the spline on the cylindrical material, and a spline of the cylindrical material. A recess and a protrusion are formed in the tooth flank of the land forming the small diameter portion in the tooth trace direction, and the protrusion is formed in the lower part of the recess and the spline protruding toward the center of the forging die. It is a forging die for shaft forming.

(Operation) The technical means functions as follows. That is, in the recess of the land of the forging die for spline shaft forming,
If the cylindrical material is sequentially pressed from above, the material that flows due to the molding of the spline into the cylindrical material is filled above the land portion, but at this time, in the spline large diameter portion and the tooth surface portion,
As the small-diameter portion is extruded, a force acts in the direction of the center of the cylindrical material, causing sag in the spline. When the extrusion molding proceeds further, the convex portion (smaller than the dimension of the sagging portion) protruding toward the center of the mold with respect to the concave portion is molded to the final dimension and extruded downward. In this molding, since the molding amount is very small and the small diameter part has already been molded, no force acts in the center direction, so no sagging of the surface of the front and rear ends of the work occurs, A spline shaft or gear shaft with precise dimensions can be molded.

(Examples) Examples will be described below.

1 to 3, reference numeral 1 is a forging die for spline shaft forming showing an embodiment of the present invention, and 2 is an uneven spline formed on the inner periphery of the die 1.

2a is a land portion, a large diameter portion and a concave portion 2b and a convex portion 2c having a predetermined size are formed on the tooth surface, and 3 is a spline relief portion.

The operation of the mold will be described. In FIGS. 4 to 7, 3 is a punch, 4 is a mandrel, and 5 is a work for forming splines on the outer peripheral surface.

When the work 5 is inserted into the die 1 together with the mandrel 4 and is pressed by the punch 3, the tip 5a of the work 5 flows into the large-diameter recess 2b provided on the land 2a of the die 1. However, a force toward the center of the spline large-diameter portion and the tooth surface portion is applied to the spline large-diameter portion and the tooth surface portion.
Sagging occurs as shown in.

When the punch 3 further descends, the work 5 has an outer periphery of the correct size formed by the convex portion 2c of the land. Here, the dimension of the land portion 2c is set to be 0.1 to 0.2 mm smaller than the dimension of the sag generating portion, so that the sag generated in the land portion 2b is eliminated.

In addition, since the amount of molding on the land 2c is very small and the small diameter portion has already been molded and the force toward the center does not act, sagging does not occur again (Fig. 5).

Next, raise the punch 3, insert a new work 6,
When the work 6 is pressed by the punch 3, the rear end of the work 5 is located at the upper portion 2b of the land 2a, which is 15a of the prior art shown in FIG.
However, when the work 6 is further lowered by the punch 3, it is formed into the correct size by the convex portion 2c of the land portion and pushed out below the die 1 (Fig. 6). .

As a result, as shown in FIGS. 7A and 7B, the work 5
The generation of sagging does not occur at the front end portion 8a and the rear end portion 8b of the surface 8, and the spline shaft 5 having a precise dimension is formed. 7
Is a spline.

〔The invention's effect〕

The present invention has the following effects. That is, in the conventional molding using a die, sagging occurs on the surface of the product, and therefore, the die is struck twice in order to correct the dimension of the sagging. Since the sagging can be eliminated, it is not necessary to remove the sagging portion, the yield is very good, and the double hitting is not necessary, which results in a great cost reduction.

[Brief description of drawings]

FIG. 1 is a sectional view of this embodiment, FIG. 2 is an enlarged view of an essential part of FIG. 1, FIG. 3 is a sectional view taken along line AA of FIG. 2, and FIGS. 4 shows the situation immediately after the work is inserted, FIG. 5 shows the work being processed, and FIG. 6 shows the situation in which the second work is inserted. FIG. 7 is an explanatory view of the work, (a) is a sectional view of the work,
(B) is an explanatory view of a main part of the surface of the work, FIG. 8 is an explanatory view of a conventional example, (A) is a plan view of a spline hole, (B) is a cross-sectional view of a mold, and (C) is a surface sag. FIG. 1 …… Forging die, 2 …… Spline, 2a …… Land, 2b ……
Recess at the top of the land, 2c ... Protrusion at the bottom of the land

Claims (1)

(57) [Claims] 1. A forging die for spline shaft forming, wherein a spline is formed on the outer circumference of a solid or hollow cylindrical material by extrusion molding, wherein the forging die for spline shaft forming has a spline on the cylindrical material. The land portion for forming the spline of the cylindrical material is provided with a concave portion and a convex portion in the tooth flank direction in the tooth surface of the land portion forming the small diameter portion of the spline. A forging die for forming a spline shaft, which is formed at a lower portion and protrudes toward the center of the forging die.