JP2541198B2 - Sintered oil-impregnated bearing manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a sintered oil-impregnated bearing.

"Prior Art" A sintered oil-impregnated bearing is a bearing that can be used in a self-lubricating state by impregnating oil by utilizing the porosity of a sintered body.

FIG. 3 shows an example of a conventionally known sintered oil-impregnated bearing.

The bearing 1 shown in this figure has a Cu layer 2 on the inner diameter side and an Fe layer 3 on the outer diameter side. The inner diameter side is the Cu layer 2 because Cu has excellent sliding characteristics and excellent corrosion resistance. The outer diameter side is the Fe layer 3 because Fe is more than Cu. It has high mechanical strength and can withstand a high load, and the raw material powder is inexpensive. This bearing 1 has the advantages of both Cu and Fe, and is extremely excellent in terms of sliding characteristics, corrosion resistance, strength and the like.

[Problems to be solved by the invention] By the way, in the above bearing, while having the above-mentioned advantages, the interface between the inner and outer layers during contraction after sintering is different because the inner and outer layers have different thermal expansion coefficients. There are problems that the joining force becomes weak, a pressing machine having a complicated structure must be used at the time of molding, the molding process becomes complicated, and the molding speed cannot be increased.

Here, a conventional forming method for manufacturing the bearing will be described. As shown in FIG. 4 (a), the lower punch 4 is divided into an inner side and an outer side.
Of the a and 4b, the outer lower punch 4b is lowered, the outer space of the partition plate 5 is filled with Fe powder, and then the inner lower punch 4a is made the same as the outer lower punch 4b as shown in FIG. The distance is lowered and the inner space of the partition plate 5 is filled with Cu powder. Next, the partition plate 5 is lowered to bring it into contact with the Cu layer of the Fe layer, and in this state, Fe and Cu particles are compressed between the lower punches 4a and 4b and between the partition plate 5 and the upper punch 6. After that, the lower punches 4a, 4a and the partition plate 5 are moved upward to push up the compressed compact S. A compression molded product having a predetermined shape is obtained by the above method.

As described above, in order to obtain the compression molded body S which is the base of the bearing, the structure of the lower punch is divided into the inner and outer parts 4a and 4b, and the partition between the both 4a and 4b is used. It is necessary to interpose the plates 5 and arrange them individually so as to be vertically movable, which complicates the structure of the press machine. Further, since the inside and outside of the partition plate 5 must be separately filled with particles in order to form the molded body S, the filling of the particles becomes troublesome, which causes the above-mentioned problem that the molding speed cannot be increased. Of.

The present invention has been made in view of the above circumstances and, of course, has advantages of both Fe-based and Cu-based, and can strongly maintain the interfacial bonding force between Fe-based and Cu-based, and the compression molding in the middle stage. (EN) A manufacturing method suitable for producing a sintered oil-impregnated bearing in which the structure of a press machine used for obtaining a body is simplified, and further, the molding process is simplified to increase the molding speed. To aim.

"Means for Solving Problems" A method for manufacturing a sintered oil-impregnated bearing according to the present invention, particles formed by coating Fe or Cu-based Cu or Cu alloy on the outer side of the powder are mutually The upper and lower punches that are brought into contact with and separated from each other, the inner surface of the die parallel to the moving direction of these punches, and the outer surface of the core rod arranged in the center thereof and parallel to the moving direction of the punch are compression-molded, When the subsequent compact is pushed up by the lower punch disposed below it and taken out, the core rod is integrally moved upward at the same speed as the compression compact and taken out, and the compression compact is taken out from the die. The core rod is lowered from the compression molded body and pulled out, and then the taken out compression molded body is heated and sintered.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view of a sintered oil-impregnated bearing manufactured by the manufacturing method according to the present invention, and FIGS. 2 (a) to 2 (d) are sectional views showing characteristic portions of the manufacturing method.

As shown in FIG. 1, the bearing 10 shown here has a uniform structure without being divided into an inner side and an outer side unlike the conventional example described above. The individual particles 11 constituting the bearing 10 are made of Fe-based (Fe alone or an alloy of Fe and Cu) powder 11a as a core, and Cu or Cu alloy 1 is provided on the outside thereof.
1b is covered.

Next, the method of manufacturing the bearing 10 will be described.
Ring-shaped lower punch 14 arranged between the core rod 13 and the core rod 13.
Is lowered by a predetermined amount, and the space above it, that is, the die 12,
The space surrounded by the core rod 13 and the lower punch 14 is filled with the particles 11 described above. Here, as shown in FIG. 1, the die and the core rod have an inner surface or an outer surface parallel to the moving direction of the upper punch and the lower punch, that is, a cylindrical inner and outer surface arranged along the vertical direction. Then, the packed particles between the lower punch 14 and the upper punch 15
The 11th group is compressed to form a compact S.

Next, the lower punch 14 is moved upward to push the above-mentioned compact S to the outside. At that time, at the same time, the core rod 13 is integrally moved upward at the same speed as the molded body S. This is due to the friction between the compression molded body S and the core rod that occurs when a fixed core rod is used.
This is to prevent peeling of the Cu layer or Cu alloy layer A.

Then, the core rod 13 is lowered. At this time, the compression-molded body S is not surrounded by the die 12 and is elastically deformed outward. Therefore, the inner Cu layer or the Cu alloy layer A is very likely to be peeled off by friction with the core rod 13. Few.

Next, the compression molded body S is taken out, heated and sintered.
Thus, the bearing 10 shown in FIG. 1 is obtained.

When the molded body S is manufactured, the content of Cu or Cu alloy in the coating powder used is preferably 3 to 50% by weight. This is because if the content is 3% or less, the coating becomes insufficient, and if it is 50% or more, the coating becomes unnecessary and the cost becomes high.

Cu 20 wt% powder is used as the coating powder, and the second
A bearing was made using a movable core rod 13 as shown. The average thickness of the Cu layer inside the bearing was about 0.01 mm. This value is the optimum Cu layer thickness of 0.
It is within the range of 005 to 0.4 mm.

"Effects of the Invention" As described above, according to the method for manufacturing a sintered oil-impregnated bearing according to the present invention, when a molded body is produced, the core rod is integrally moved upward at the same speed as the molded body after compression to form the molded body. Since the core rod is extracted from the molded body after the body is extracted from the die, the Cu layer or Cu alloy layer on the inner diameter side obtained during molding does not peel off due to friction with the core rod, and has excellent sliding characteristics. The bearing can be surely obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG.
~ (D) is a cross-sectional view for explaining the manufacturing method of the present invention, Fig. 3 is a cross-sectional view for showing a conventional bearing, and Figs. 4 (a) to (d) are for explaining a conventional method for manufacturing a compression molded body. FIG. 10 …… Bearing, 11 …… Particles, 11a …… Fe-based core, 11b ……
Cu or Cu alloy layer, 12 ... die, 13 ... core rod,
14 …… Lower punch, 15 …… Upper punch.

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Claims (1)

(57) [Claims] 1. An upper punch and a lower punch, which are made of Fe-based powder as a core and are coated with Cu or a Cu alloy on the outside thereof, are brought into contact with and separated from each other in the vertical direction, and are parallel to the moving direction of these punches. When performing compression molding between the inner surface of the die and the outer surface of the core rod arranged in the center and parallel to the moving direction of the punch, when the compacted body after compression is pushed up by the lower punch arranged below it and taken out. , The core rod is integrally moved at the same speed as the compression molded body and taken out,
A method for producing a sintered oil-impregnated bearing, comprising: lowering and pulling out a core rod from a compression molded body in a state where the compression molded body is taken out from a die, and then heating and sintering the taken out compression molded body.