JP2743240B2 - Inner diameter spline molding method - Google Patents

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 an inner diameter spline on the inner peripheral side of a cylindrical work.

[0002]

2. Description of the Related Art As a means for forming an inner diameter spline on an inner peripheral portion of a work, it is a general means to press-fit a multi-stage broach into the inner peripheral portion to cut off a valley portion of the spline. However, this method requires a long time for processing and increases the cost, so that many forming means have been used. As the forming means, there is provided a method in which a tooth-shaped forming surface is provided on both the die and the punch, a thin cylindrical body is used as a work, and the die and the punch are used to form a zigzag cross-section by ironing (Japanese Patent Application Laid-Open No. 61-296926). JP-A 1-27
8918).

[0003] However, the work made by this method cannot be processed unless the meat is thin, and there is a disadvantage that sufficient strength cannot be obtained.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to form an inner diameter spline on the inner peripheral surface of a thick cylindrical portion by press working.

[0005]

Means for solving the above-mentioned problems in the present invention is to provide a core mold having spline-molded teeth on the outer periphery,
In a mold which is fixed at the center of a die having a cylindrical inner peripheral surface to form a ring-shaped molding space, a cylindrical portion having an inner diameter substantially equal to the outer diameter of the core mold and an outer diameter larger than the inner diameter of the die Is characterized by being press-fitted in the axial direction by a pressure punch.

[0006]

When a work is press-fitted into the molding space, the work is advanced while being squeezed by the inner peripheral surface of the die, and the flesh moves to the valley side of the spline molding teeth on the outer periphery of the core mold to form an inner diameter spline.

[0007]

An embodiment will be described below with reference to the drawings. 1 and 2, reference numeral 1 denotes a mold for carrying out the present invention.
Is a combination of the die 2 and the core 3. Die 2
It is a split type, consisting of half portions 2a and 2b, and a cylindrical inner peripheral surface 4,
A bottom surface 5 and a center hole 6 are provided, and a chamfered portion 4 a is provided at an opening of the inner peripheral surface 4.

The core mold 3 has a tapered portion 3a at the upper end and spline forming teeth 7 on the outer peripheral surface.
The shaft portion 9 is fitted into the center hole 6 of the die 2, and the step portion 8 is combined with the die 2 in a state of sitting on the bottom portion 5 to form a ring-shaped molding space 10. I have.

Reference numeral 11 denotes a hollow pressure punch for pushing the work 12 into the molding space 10;
As shown in FIG. 3, a cylindrical portion 13 rising from the flat plate portion 12a.
Is provided.

The relationship between the size of the work 12 and the size of the molding space 10
Sets the outer diameter of the cylindrical portion 13 to D₁, Inner diameter D_Two, Height is H
And the inner diameter of the molding space 10 is d₁, Height h, outside the core mold 3
Diameter d _TwoThen D₁> D₁, H ≧ h, D_Two≒ d_TwoAnd
You.

When the work 12 is fitted to the core mold 3 and pressed by the pressure punch 11, the work 12 is press-fitted while being guided by the chamfered portion 4a or the core mold 3, and the dimension of D ₁ > d ₁ is satisfied. Due to the difference, the cylindrical portion 13 is narrowed down and descends as shown in FIG. 2 while reducing its diameter. The inner peripheral surface thereof is also reduced in diameter and pressed against the surface of the spline forming teeth 7 to form the spline teeth 14.

The height H of the cylindrical portion 13 is
When the relationship of H> h is higher than the height h of 0, the cylindrical portion 13 receives a compression action in the vertical direction at the end of the stroke,
In addition to the diameter-reducing action due to D ₁ > d _1, a wall-thickening action is exerted, and is pushed into the molding space 10 without any gap, whereby a more accurate spline is molded.

After the molding is completed, the halves 2a and 2b of the die 2 are opened to the left and right, and the divided portion of the bottom portion 5 is retracted to a position where it separates from the step 8 but does not separate from the cylindrical portion 13. The work 12 is dispensed by being lowered and pulled out from the cylindrical portion 13.

[0014]

As described above, since the inner diameter spline is formed by narrowing the outer diameter of the work in the radial direction on the inner peripheral surface of the die having a smaller diameter, the work can be formed even if the work is thick. In addition, since unnecessary grooves are not formed on the outer periphery of the work, a high-strength inner diameter spline can be made, and it can be formed with a single stroke of the pressure punch. It can be produced very efficiently. And since it is formed by the movement of the meat in the radial direction, the meat does not shift in the tooth trace direction as in the case of the ironing molding, so that the end of the work does not have burrs, and there is an advantage that there is no need to perform the deburring work. Have.

Furthermore, if the length of the work is made longer than the height of the molding space, an additional compressive force in the axial direction can be applied to the work, and the work is sufficiently compressed so that no gap is formed in the molding space. Therefore, there is an advantage that a highly accurate inner diameter spline can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an apparatus for implementing the present invention.

FIG. 2 is a longitudinal sectional view of the same device during operation.

FIG. 3 is a perspective view of a product.

[Explanation of symbols]

1 Mold 2 Die 3
Core mold 4 Inner peripheral surface 7 Spline molded teeth 10
Forming space 11 Pressure punch 12 Work

Claims (1)

(57) [Claims] 1. A core mold having spline-formed teeth on the outer periphery,
In a mold which is fixed at the center of a die having a cylindrical inner peripheral surface to form a ring-shaped molding space, a cylindrical portion having an inner diameter substantially equal to the outer diameter of the core mold and an outer diameter larger than the inner diameter of the die A spline forming method, characterized in that a work having a shape is press-fitted in an axial direction by a pressure punch.