JPH01184207A - Manufacture of sintered part having flange - Google Patents

Abstract

PURPOSE:To reduce taper of outer peripheral part of a flange in a sintered part and to improve dimensional accuracy by arranging steps at end face of pressurizing side in an upper punch and end face of shoulder part in a die corresponding to the above end face at the time of pressurized-compacting a sintering part having the flange at one end thereof. CONSTITUTION:Cavity forming with the upper punch 1, die 2, lower punch 3 and core 4 is corresponded to the part A to form the sintering part A having the flange by pressurizing the upper punch 1. Then, at the end face 1a of pressurizing side in the upper punch 1 and/or the end face 2a of the shoulder part in the die 2 corresponding to this end face 1a, the steps 1b, 2b are arranged so as to use the gap part 5 developed between end face of the flange F in the sintering part A and the steps, to escaping position of bulging stress acting to the flange F. Further, the height H of the steps 1b, 2b is made to only a little, such as < about 1mm. By this method, the taper developed at the outer peripheral face of the flange is reduced and the dimensional accuracy of the part A is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a sintered part with a flange at one end with high precision.

[Conventional technology]

When sizing a flanged sintered part as shown in Fig. 4, □ Conventionally, four forming elements of a press, namely the upper punch 1, die 2, lower punch 3, and core 4 shown in Fig. The cavity formed between them is made to match the shape of part A, and when the die and the outer side of part A come into contact during pressurization, a gap is created between the four molding elements 1.2.3.4 and part A. The final pressurization by the upper punch 1 is performed in the absence of any.

Note that the core 4 may be omitted depending on the shape of the component.

[Problem to be solved by the invention]

When pressure is applied from the upper bunch 1 using the conventional method described above,
The outer diameter of the part A begins to expand, and the outer peripheral surface of the collar F of the part begins to come into contact with the inner surface of the die 2. When further pressure is applied, the contact resistance of the outer circumferential surface of the flange F with the die increases, and as shown by the arrow, one side of the flange F tries to swell further with a greater force, and the other side of the flange receives the force from the die. Pressure force is not sufficiently transmitted to the sides. Therefore, when part A is taken out from the cavity after being pressurized, one side of the flange F, which has received a large amount of pressure, greatly expands in diameter due to the residual stress, and the outer peripheral surface of the flange is as shown by the chain line in Figure 4. There was a problem in that the dimensional accuracy was not sufficiently increased due to the tapering.

The present invention aims to eliminate such problems and improve the dimensional accuracy of sintered parts by sizing and coining.

[Means to solve the problem]

In order to eliminate the above-mentioned problems, this invention has a step 1b as shown in FIG.
2b, or give these surfaces a curvature of 9 planes 1a' and 2a' as shown in FIG. (See Figure 3) is pressurized as a refuge for the swelling stress acting on the flange F.

It is sufficient to have at least one of the steps 1b and 2b, but as shown in the figure, if both are provided at different positions in the radial direction of the flange F, the bending action described later will occur on the tsuba F, which will reduce the effect of the invention. maximized.

One of the nine surfaces 1a' and 2a' in FIG. 2 can be omitted, but if they are provided correspondingly as shown in the figure, a bending action will occur on the collar F.

In addition, the height dimension H1 of the steps 1b and 2b or the 9th surface 1a',
Although the retreat amount H' of one edge of 2a' is expressed in an oversized manner for ease of viewing the figure, the actual value may be a very small value of less than 1 mm.

[Effect]

When the forming element is configured as shown in Fig. 1 or 2 and pressurized, bending stress as shown by the arrow in Fig. 3 is applied to the flange F of the part A, and the swelling force of the flange is applied to the air gap. 5, the contact resistance between the outer peripheral surface of the collar F and the inner surface of the die 2 becomes smaller. Therefore, the pressurizing force is sufficiently transmitted to the other surface of the flange F, and the difference in the radially outward expansion force at each part in the thickness direction of the flange is reduced, reducing the Taber slope of the outer circumferential surface. .

For example, when sizing a sintered part A with a flange F diameter of 60 mm, a thickness of 7.5 mm, and a density of 6.8, H
= 0.2m11, with a step of w = 2mm,
The difference in outer diameter between one end and the other end of the tsuba, which was 0.030 mm, was almost halved to 0.016 mm by press working without a step. Note that if the step or the rounded surface is provided only on either the upper punch or the die, the bending action of the flange will not be obtained, and the dispersion of the swelling force against the gap 5 will be somewhat poor, but this still does not affect the invention. objective can be achieved.

〔effect〕

As described above, in the sizing and coining processes, this invention creates a stress relief area at a position along the end face of the sintered part's collar in the pressing direction, and reduces the contact resistance of the outer circumferential surface of the part's collar with the die during pressurization. Since the difference in the swelling force at each part in the thickness direction of the collar is reduced, the taper on the outer circumferential surface of the collar due to this difference is reduced, and the dimensional accuracy of the part is improved. Therefore, it is particularly effective when used in manufacturing sintered parts that require high precision.

[Brief explanation of the drawing]

1 and 2 are both cross-sectional views of the molding element used in the present invention, FIG. 3 is a cross-sectional view for explaining the action of the molding element in FIG. FIG. 5 is a cross-sectional view showing an example of a connecting part, and FIG. 5 is a cross-sectional view showing a conventional sizing process. 1...Top punch, 1a...End face, 1b
...Step, 1a... End face, 2...
...Die, 2a...End face of shoulder, 2b...
...Step, 2a'...R surface, 3...Lower punch, 4...Core, 5...Gap, A
... Sintered parts, F ... Tsuba. Patent applicant Sumitomo Electric Industries Co., Ltd. Okayama Sumiden Precision Co., Ltd. Agent Kama 1) Text 2N

Claims (1)

[Claims] In the sizing and coining process, a sintered part with a flange at one end is placed in a cavity created between an upper punch, a die, a lower punch, or a molding element in which a core is added and pressurized with the upper punch. A step or curvature that has a gap between the pressure side end face of the sintered part, the end face of the die shoulder facing it, or both, is provided with a step or curvature that has a gap between it and the shape of the sintered part before pressurization, and the gap is connected to the flange of the sintered part. A method for manufacturing a sintered part with a flange, characterized in that pressurization is applied as a relief for swelling stress acting on the flange.