JPS63286504A - Production of sintered part - Google Patents

Abstract

PURPOSE:To improve accuracy of working reference plane and to produce a sintered member having high accuracy by forming small projection at upper face or lower face of a green compact at the time of compacting metal powder and machining it after sintering. CONSTITUTION:At the time of compacting the metal powder, by arranging three or more of small recessed parts 3 at part of the upper or lower punch 2, (5), the metal powder is compacted to make the green compact 7 having small injection 3 at the upper face or the lower face. After sintering the green compact 7, it is pushed in a die 8 together with a center rod 6 with upper and lower punch 2, 5 by press, and size thereof is corrected to make the sizing sintered compact 4. The grinding, cutting, etc., is executed to the sizing sintered compact 4 while using the plane having the projection 3 as the reference plane, to finish to the finish sintered member 1. The shape of the projection 3 is to be ring-state, etc., and height thereof is to be about 0.05-0.5 mm.

Description

Detailed Description of the Invention 46 Object of the Invention (a) Industrial Application Field This invention relates to a method for manufacturing sintered parts by molding, sintering, and machining metal powder to produce precision mechanical parts. It is.

(b) Conventional technology Traditionally, sintered parts have been manufactured by press-forming Kinpo powder, heating and sintering it to make a sintered body, sizing it to adjust its dimensions, and then using machines such as polishing and cutting. It is usually finished by processing.

(c) Problems to be Solved by the Invention In the conventional method described above, even if the sintered body is press-formed into a shape as close as possible to the product, distortion and warpage occur due to sintering. Even with sizing, it is not possible to completely correct distortions, etc. Therefore, the reference surface becomes greatly unstable during machining after sizing, making it impossible to obtain product accuracy in terms of parallelism, perpendicularity, etc., and machining costs There was also a growing problem.

1. Structure of the Invention (a) Means for Solving the Problem This invention provides a method for manufacturing sintered parts, ``When metal powder is press-molded, the part is formed into a shape with small protrusions on the top or bottom surface. In this method, the sintered body is sintered to produce a sintered body, the sintered body is subjected to sizing or light processing, and finally machined.

The present invention will be explained below using specific examples and drawings.

For example, to manufacture a cylindrical sintered part (1) as shown in Figure 1, a press is used to press metal powder between the die (8) and the center rod (6) as shown in Figure 2. Forming is performed by pressing using a punch (2) and a lower punch (5). In the present invention, as shown in FIG. 2, three or more small recesses (3 ) and press the metal powder into a compact (7) as shown in FIG. When the molded body (7) is sintered, a sintered body having almost the same shape is obtained, but this sintered body has irregularities in dimensions and perpendicularity between the outer circumferential surface and the end face due to sintering distortion.

As shown in FIG. 4, the sintered body is pressed into the center rod and die using upper and lower punches using a press, and sizing (dimensional correction) is performed to obtain a sized sintered body (4). Sizing sintered body (
4) is polished or cut using the surface of the protrusion as a reference surface to produce the final sintered part.

In this case, the shape of the protrusion may be a ring shape (which may be partly missing) or other shapes. It goes without saying that these protrusions may be formed on both end faces of the component. If the height is too low, it will not be sufficient to eliminate the effects of distortion and warpage during sintering, and if it is too high, the machining allowance will increase during machining, resulting in high costs. 50 is good.

Although the above description has been made with respect to cylindrical parts, it can also be applied to disc-shaped and other irregularly shaped parts that are manufactured in the same process. Furthermore, methods other than sizing, such as aligning the surface of the protrusion with sandpaper or the like at right angles to the side surface of the sintered body, are easier than in the conventional method.

(b) Effect When sizing a sintered body using the method of the present invention, the fourth
As shown in the figure, the only contact between the lower surface of the sintered body and the lower punch (5) of the press is the protrusion (3), so the contact pressure is high and the pressure-receiving area is small, so the protrusion (3) is easily deformed. The tip surface of the protrusion is corrected to be at a correct right angle to the outer circumferential surface, and the perpendicularity accuracy between the outer circumferential surface and the tip surface of the protrusion is significantly improved compared to the conventional method.

According to experiments by the inventors, the outer diameter is 70 flφ and the thickness is 10 mm.
In the case of a disk-shaped portion of fl, the width is 2ff and the center diameter is 40H1
When a ring-shaped protrusion with a height of 0.15ff is provided on one side, the squareness accuracy after sizing is 0.01 to 0.02 compared to the conventional one.
jff was 0 to 0.0051'ff, and the accuracy was significantly improved.

FIG. 5 shows the case where a sintered body made of iron-based powder metallurgy is finished by polishing. In the case of the conventional method, the fifth
As shown in Figure (a), the sizing sintered body (4) is attached to a magnetic chuck (9) of a polishing machine, and one side is polished and removed α0, and then the opposite side is polished and removed (1G).

However, in this method, as can be seen from the drawings, the accuracy of the perpendicularity between the outer circumferential surface and the end face of the component is the same as the accuracy of the sizing sintered body (4), and is not improved by polishing. According to the method of the present invention, as shown in FIG. 5(b), first, the end face of the sizing sintered body (4) with the projection (3) is attached to the magnetic chuck of a polishing machine, and the opposite face is polished and cut off. do.

Next, turn over the sizing sintered body (4) and turn the protrusion (3) over.
) is polished and cut σQ. Since the sizing sintered body of the present invention has high perpendicularity accuracy between the end face with the protrusion and the outer peripheral surface, a sintered part with high perpendicularity accuracy can be obtained after polishing. Furthermore, as can be seen from the drawings, there is an advantage that fewer parts are removed.

FIG. 6 is a drawing showing a case in which a sintered body is cut using a lathe equipped with a collet chuck. When the sizing sintered body (4) according to the conventional method is attached to a collet chuck Ql) and cut, as shown in FIG. 6(a),
The squareness of the sintered body becomes the squareness of the cut sintered part, and as shown in the drawing, the chuck grips only a portion or one point of the sintered body, making the chuck fixation unstable. Moreover, the sizing sintered body is easily damaged by the chuck. When the sizing sintered body according to the method of the present invention is mounted on a collet chuck and cut using the protrusion (3) as a reference plane as shown in FIG. Since this directly becomes the perpendicularity of the machined sintered part, it is possible to obtain a sintered part with higher surface angle precision than conventional products, and it is also possible to prevent chuck scratches on the sizing sintered body.

(c) Example As shown in Fig. 3, outer diameter 708φ, inner diameter 62 shoulder φ,
A cylindrical part with a height of 10 mm was manufactured through the steps of press molding, sintering, sizing, and machining.

At that time, the parts manufactured by the method of the present invention were manufactured using the conventional method and the press-formed body having a ring-shaped protrusion with an inner diameter of 6211 M, an outer diameter of 65 mm, and a height of 0.251 rll on one side of the part. The surface angles of the outer peripheral surface and end surface of the joint parts were measured and compared. The results are shown in the table below.

Front (surface angle of outer circumferential surface to machined surface) αQ...Removed portion, αυ...Collet chuck.

From the above results, it can be seen that sintered parts with very good surface angles can be obtained according to the present invention.

Effects of the Invention As explained in detail above, the manufacturing method of the present invention improves the precision of the processing reference surface (surface angle, flatness) compared to the conventional method, and produces sintered parts with high precision as a product. It is possible and effective.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the sintered part. FIG. 2 is a sectional view of pressing a molded body, FIG. 3 is a perspective view of the molded body of the present invention, and FIG. 4 is a sectional view of a sizing press. Figure 5 (aL
(b) is a front view showing a state in which the sizing sintered body is being polished, and sixth figures (a) and (b) are sectional views showing the state in which the sizing sintered body is being cut by a collet chuck. (1)... Sintered parts, (2)... Upper punch, (3)
... recess, protrusion, (4) ... sizing sintered body, (5) ... lower punch, (6) ... center rod, (7)
...Sintered compact, (8)...Die, (9)...
・Magnetic Chuck, Agent Patent Attorney 1) Naka Osamu Bubu Figure 1 Bubu Figure 3 Figure 2 Figure 41 Section C] Section (α) 5 Figure 6 (A

Claims (1)

[Claims] 1. In a method for manufacturing a sintered part, when metal powder is press-molded, one end surface or both end surfaces of the molded body may have a ring shape, a ring shape with a partial defect, or a ring shape with a partial defect. 2. A method for manufacturing a sintered part, characterized in that the molded body is produced by forming more than 10 small protrusions, and then processing after sintering, the height of the protrusions is 0.05 to 0.50 mm. A method 3 for manufacturing a sintered part according to claim 1, characterized in that the sintered body is sized and polished or cut using the surface of the protrusion as a reference surface. A method for manufacturing a sintered part according to claim 1 or 2.