JPS5852729B2 - Method for forging parts with undercuts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forging a component having an undercut on its inner surface.

Conventionally, parts with undercuts on the inner surface generally cannot be forged, and to manufacture this type of part, Figure 1a
As shown in the figure, a part A without an undercut is forged, and the part A is machined to form an undercut part B.

Further, as shown in FIG. 1, there is an example in which the undercut portion is simply formed by a mouth drawing process, but this forming method has a problem in terms of the accuracy of the inner surface.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a forging method that makes it possible to manufacture parts having an undercut on the inner surface.

Hereinafter, an embodiment of the present invention will be described in which a ball joint housing 1, which is an automobile part, is manufactured as shown in FIG.

Conventionally, to manufacture this ball joint housing 1, it was forged into a shape with a concave portion 3 having a straight inner surface 2, and then the inner surface 2 was machined into a spherical surface 4 and further polished. The process becomes complicated.

FIGS. 3, 4, and 5 show an apparatus for carrying out the method of the present invention, and the details thereof will be explained below.

A die 11 is provided on the press bed 10, and a recess 12 having the same shape as the outer peripheral surface 5 of the ball joint housing 1 is formed in the die 11, and the recess 12 passes through a vertical hole 13 to the lower surface 11a of the die. Open and its vertical hole 13
A vertical hole 15 is formed in the knockout 14 into which a knockout 14 is inserted.

A punch 17 is suspended and fixed to the press slide 16 by a holder 18, and a hole 19 is bored in the axis of the punch 17, and a pin 20 is inserted thereinto, and the pin 20 is moved and held downward by a spring 21. At the same time, a punch sleeve 22 is fitted onto the outer circumferential surface of the punch 17, and the punch sleeve 22 has a spring 23 and its upper collar 22a engages with the inward stepped portion 2 of the holder 18.
It is moved and held so as to come into contact with 4.

The tip 17a of the punch 17 is a downwardly truncated hexagonal pyramid, and a cam piece 26 is provided on each surface 25 of the punch 17, and an upper spring 27 and a lower spring 28 are wound around the upper and lower parts of each cam piece 26. Each cam piece 26 is urged to contract in the circumferential direction so as to come into close contact with each surface 25.

The cam piece 26 has an inclined inner surface 29 that is in close contact with each surface 25 of the downward truncated hexagonal pyramid of the punch 17 and an outer surface 30 that has approximately the same shape as the spherical inner surface 4 of the ball joint housing 1. An axial guide groove 31 is formed, and a guide pin 32 that fits into the guide groove 31 protrudes from each surface 25.

In the contracted state, each of the cam pieces 26 is located inside the inner diameter inlet portion 6 of the ball joint housing 1 having a predetermined shape, and a spherical protrusion 33 is formed on the outer surface 30 of the cam piece 26.

The tip of the pin 20 protrudes beyond the punch tip surface 17b, and a plate 34 is fixed thereto.

Next, the manufacturing method will be explained.

As shown by the imaginary line in FIG. 4, a ball joint housing 1 (hereinafter referred to as a semi-finished product) having a recess 8 having an inner surface 7 that is smaller than the factory shape and substantially straight is preformed,
It is placed into the recess 12 of the die 11.

At this time, the rod-shaped portion 9 is fitted into the vertical hole 15 of the knockout 14.

Next, the press slide 16 is lowered to lower the punch 17, and the plate 34 and cam piece 26 are press-fitted into the recess 8 of the semi-finished product 1'.

When the plate 34 descends further, the bottom wall 8' of the recess 8
The punch sleeve portion 22 contacts the cam piece upper surface 26a.
comes into contact with.

This is the state on the right side in FIGS. 3, 4, and 5.

When the pin 20 is lowered further than that, the pin 20 and the punch sleeve 22 are raised relative to each other against the spring 23, and only the punch 17 is lowered.

When the punch 17 is lowered, each cam piece 26 is expanded outward by each surface 25 of the truncated hexagonal pyramid, and its outer surface 30 is pressed against the inner surface 7 of the semi-finished product 1'.

This state is the state on the left side in FIGS. 3, 4, and 5.

After finishing machining into a predetermined shape, the press slide 16 is raised and the punch 17 and cam piece 26 are extracted.

At this time, the cam piece 26 is contracted by the spring to an inner position where it does not interfere with the undercut portion 6, so that the cam piece 26 can be easily extracted.

Then, when the punch 17 rises and is removed from the die 11, the ball joint housing 1 is pushed up and ejected from the recess 12 of the die 11 by the knockout 14.

According to the forging method of the present invention, the inner surface 7 of the semi-finished product 1' can be hammered with the cam piece 26 to form the inner surface 3 of a predetermined shape, and a part having an undercut can be produced by forging.

[Brief explanation of drawings]

FIG. 1 is a general cross-sectional view of a part with an undercut. FIG. 2 is a cross-sectional view of a ball joint housing with an undercut. FIGS. 1 is an explanatory diagram of an apparatus for carrying out the
FIG. 3 is an overall vertical sectional view, FIG. 4 is an enlarged sectional view of a main part, and FIG. 5 is a plan view. 11 is the die, 17 is the punch, and 26 is the cam piece.

Claims (1)

[Claims] 1. A semi-finished product 1' having a recess 8 smaller than a predetermined shape is placed in the recess 13 of the die 11, and a pin 20 is slidably inserted into the axis of a punch 17 whose outer peripheral surface has a tapered tip. A plate 34 is provided at the tip of the pin 20 that protrudes from the tip of the punch 17, and the plate 34 has a
The lower ends of the plurality of cam pieces 26 having outer surfaces 30 having substantially the same shape as the inner peripheral surface shape of the product are disposed along the tapered outer peripheral surface of the punch 17 and are oscillated along the axial direction of the punch 17. Each cam piece 26 is movably pivoted.
can be freely contracted and expanded in the circumferential direction, and each cam piece 26
The punch 17 is oscillated and urged so as to come into close contact with the tapered outer peripheral surface of the punch 17, so that it faces into the recess 8 of the semi-finished product 1' in a contracted state, and in this state, the punch 17 is moved up and down to form a tapered shape. By expanding and contracting each cam piece 26 with the shaped outer peripheral surface, the outer surface 30 of each cam piece 26 is struck against the inner surface 7 of the semi-finished product 1' to form the inner surface 3 having an undercut portion 4 of a predetermined shape. A method for forging a part having an undercut, characterized by: