JPH0941071A - Wear resistant sintered oilless bearing low in mating attackability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a wear resistant sintered oilless bearing low in mating attackability. SOLUTION: This sintered oilless bearing has a compsn. contg., by weight, 40 to 60% Fe, 0.1 to 5% Sn, 0.1 to 2% C, 0.05 to 1% S and 0.01 to 0.5% B, furthermore contg., at need, 0.5 to 2% MoS2 , and the balance Cu with inevitable impurities. The bearing is composed of a porous Cu-Fe-Sn sintered alloy having a structure in which free graphite is dispersedly distributed into a matrix of a Cu-Sn alloy, furthermore, free graphite grown with S components as the neucleus is dispersedly distributed into the ferritic phases, moreover, B components are distributed over the surfaces of the ferritic phases and the grain boundaries, and MoS2 is distributed over the boundary parts of the matrix and ferritic phases and having 10 to 30% porosity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has excellent compatibility with a rotating shaft, which is a mating material, and excellent self-lubricating property. Therefore, even when it is put to practical use under severe conditions, it has a very low mating attack. The present invention relates to a sintered oil-impregnated bearing showing excellent wear resistance.

[0002]

2. Description of the Related Art Conventionally, a sintered oil-impregnated bearing has been generally used as a supporting member for a rotating shaft, which is a mating member, in various drive devices. Indicates weight%), Fe: 40 to 60%, S
A composition containing n: 0.1 to 5%, C: 0.1 to 2%, and the balance of Cu and inevitable impurities, and a Cu-Sn alloy as shown in FIG. Has a structure in which the pearlite phase is dispersedly distributed in the base material of
It is well known that the porous Cu—Fe—Sn based sintered alloy having a porosity of 30% is made by impregnating the pores with oil.

[0003]

On the other hand, in recent years, the performance and size of the drive unit have been remarkably increased and the output thereof has been increased. As a result, the rotational speed of the rotary shaft, which is a structural member of the drive unit, has been increased. And the load on this tends to be high, but in the above-mentioned conventional sintered oil-impregnated bearing, the porous Cu-Fe-Sn-based sintered alloy constituting the same is used as shown in FIG. Due to the pearlite phase present in
It has low compatibility with the rotating shaft that is the mating material, and also has insufficient self-lubricating properties. Therefore, under high-speed rotation and high load conditions, it is possible to avoid strong mating aggression and accelerate the progress of wear. The current situation is that there are none.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above-mentioned viewpoints, as a result of conducting research to develop a sintered oil-impregnated bearing excellent in conformability and self-lubrication, focusing on the above-mentioned conventional sintered oil-impregnated bearing, as a result, the above-mentioned conventional sintered oil-impregnated bearing was obtained. When S and B are contained as alloy components in the porous Cu-Fe-Sn-based sintered alloy that constitutes
Since the component serves as a nucleus to precipitate free graphite, and the component B acts to promote the growth of the free graphite, the porous Cu—Fe—Sn based sintered alloy is shown in FIG. As shown in the figure, a ferrite phase of Fe as a main component is dispersedly distributed in place of the hard pearlite phase in the base material of the Cu-Sn alloy, and the S component forms nuclei along the crystal grain boundaries in the ferrite phase. The fine free graphite that has grown up is distributed and distributed,
In addition, it has a structure in which the B component is distributed along the surface of the ferrite phase and the crystal grain boundaries.
The u-Fe-Sn based sintered alloy has excellent compatibility and self-lubricity due to the soft ferrite phase and free graphite.
Further, when molybdenum sulfide (hereinafter referred to as MoS ₂ ) is added to the porous Cu—Fe—Sn based sintered alloy, as shown in the enlarged structure diagram of FIG. Since it is distributed and the self-lubricating property is further improved, it is a research that it shows extremely low opponent attack and excellent wear resistance even when it is used as a sintered oil-impregnated bearing under high speed rotation and high load conditions. The result was obtained.

The present invention was made based on the above research results, and Fe: 40 to 60%, S
n: 0.1 to 5%, C: 0.1 to 2%, S:
0.05 to 1%, B: 0.01 to 0.5%,
Further, if necessary, a composition containing MoS ₂ : 0.5 to 2% and the balance Cu and inevitable impurities, Cu-S.
The ferrite phase is dispersed and distributed in the base material of the n-based alloy, and free graphite grown with the S component as a nucleus is distributed and distributed in the ferrite phase, and the B component is further distributed along the surface of the ferrite phase and the grain boundaries. And a structure in which MoS ₂ is distributed at the interface between the green body and the ferrite phase, if necessary,
And porous Cu-F having a porosity of 10 to 30%
The present invention is characterized by a wear-resistant sintered oil-impregnated bearing that is made of an e-Sn-based sintered alloy and has low opponent attack.

Next, in the sintered oil-impregnated bearing of the present invention, the reason why the component composition and porosity of the porous Cu-Fe-Sn sintered alloy constituting the same are limited as described above will be explained. (A) Fe The Fe component has a function of forming a ferrite phase dispersedly distributed in the matrix to improve the conformability, but the proportion thereof is 4
If it is less than 0%, the proportion of the ferrite phase becomes too small, and the desired wear resistance cannot be secured, while if it exceeds 60%, the proportion of the base material becomes too small. As a result, the strength is lowered, so the ratio is set to 40 to 60%, preferably 45 to 55%.

(B) Sn The Sn component has the function of forming a solid solution with Cu to form a Cu-Sn alloy of the base material and improving the strength, but if the proportion is less than 0.1%, the desired strength is obtained. Could not be secured,
On the other hand, if the ratio exceeds 5%, the base material tends to become brittle and the attacking property of the opponent increases, so the ratio was set to 0.1 to 5%, preferably 1 to 3%.

(C) CC The C component has the function of precipitating as fine free graphite at the grain boundaries in the ferrite phase by the action of the S and B components and growing to improve the self-lubricating property. If the ratio is less than 0.1%, the distribution ratio of free graphite is too small to secure the desired self-lubricating property. On the other hand, if the ratio exceeds 2%, complete graphitization becomes difficult and cementite becomes The ratio of attack is increased to 0.1 to 2%, preferably 0.5 to 1.5%, since the attacking property of the other party becomes high due to precipitation.

(D) The S S component is an essential component for the precipitation of free graphite as described above. Therefore, if the proportion thereof is less than 0.05%, graphitization becomes insufficient and the desired self-lubricating property is not obtained. When the ratio exceeds 0.05%, the cementite precipitates to increase the attacking property of the opponent, and when the ratio exceeds 1%, the strength is reduced. ~
It was set to 1%, preferably 0.2 to 0.7%.

(E) BB The B component is distributed along the surface of the ferrite phase and the crystal grain boundaries, and free graphite deposited with the S component as a nucleus is grown at the grain boundaries in the ferrite phase. In other words, pearlite. There is an action of graphitizing cementite in the phase to convert the pearlite phase into a ferrite phase and free graphite, but if the ratio is less than 0.01%, graphitization is insufficient, and the opponent attack by residual pearlite is unavoidable. Moreover, the desired self-lubricating property cannot be obtained, and on the other hand, when the ratio exceeds 0.5%, the sinterability is deteriorated and high strength cannot be secured, so the ratio is 0.01 to 0.5. %, Preferably 0.1
It was set at 0.3%.

(F) MoS _{2 The} MoS ₂ component is contained as necessary because it has a function of improving the self-lubricating property by being distributed in the interface between the matrix and the ferrite phase as described above. Is 0.5%
If the ratio is less than the above, the desired effect cannot be obtained, while if the ratio exceeds 2%, the strength rapidly decreases. Therefore, the ratio is 0.5 to 2%, preferably 0.5 to
It was set at 1.5%.

(G) Porosity Although the pores are immersed in oil to enhance the sliding characteristics of the bearing, if the porosity is less than 10%, the sliding characteristics improving effect due to oil immersion cannot be sufficiently exerted. On the other hand, when the porosity exceeds 30%, the strength is remarkably reduced, so the porosity is set to 1
It was set to 0 to 30%, preferably 15 to 25%.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the sintered oil-impregnated bearing of the present invention will be specifically described with reference to Examples. As a raw material powder, atomized Fe-S alloy (S:
0.3% included) powder, atomized Fe powder of the same-100 mesh, electrolytic Cu powder of the same-150 mesh, same-1
00 mesh Sn powder, -100 mesh Cu-
Sn alloy (Sn: 9% content) powder, -150 mesh flaky graphite powder, -100 mesh Fe-B alloy (B: 5% content) powder, and -100 mesh MoS ₂ powder. Prepare and mix these raw material powders with the composition shown in Tables 1 and 2, and add 0.4% of this as a lubricant.
Zinc stearate was added and mixed in a V-type mixer for 30 minutes, and then pressed into a green compact at a predetermined pressure within the range of ^{2 to 3} ton / cm ² , and the green compact was decomposed with ammonia decomposition gas. Sintered under a condition of holding at a predetermined temperature within a range of 850 to 950 ° C. for 30 minutes in an atmosphere, and having a porosity and a composition substantially the same as the composition shown in Tables 1 and 2 By forming a high quality Cu-Fe-Sn-based sintered alloy body and vacuum-immersing synthetic oil in it, both have outer diameter: 16 mm ^φ × inner diameter: 8 mm ^φ × length: 8 mm, Moreover, the sintered oil-impregnated bearing 1 of the present invention in which the porous Cu—Fe—Sn based sintered alloy body has the structure shown in FIGS.
15 to 15 and the conventional sintered oil-impregnated bearings 1 to 7 having the structures shown in FIG.

Then, each of the various sintered oil-impregnated bearings obtained as a result was fitted into the supporting jig 1 of the radial friction tester shown in the schematic front view of FIG.
A rotary shaft 3 made of C (carbon steel) is inserted with a clearance of 25 μm, and a high load W of 1.05 kgf / cm ² is applied to the rotary shaft 3 through a sintered oil-impregnated bearing 2, a supporting jig 1, and a ball bearing 4. The rotating shaft was rotated at a high speed at 4000 rpm in a state of being subjected to a wear test, and a wear test was performed for 100 hours of operation. After the test, the maximum wear depth of the sintered oil-impregnated bearing and the rotating shaft was measured. The measurement results are shown in Tables 1 and 2.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

From the results shown in Tables 1 and 2, the sintered oil-impregnated bearings 1 to 15 of the present invention are basically dispersed in the base material despite the severe conditions of high speed rotation and high load operation. The distributed ferrite phase and the fine free graphite dispersed and distributed in it provide excellent conformability and self-lubricating properties, so the rotating shaft, which is the mating material, has less wear, that is, low mating attack and excellent wear resistance. On the other hand, in conventional sintered oil-impregnated bearings 1 to 7, not only is the remarkably high opponent attack property under the severe conditions described above due to the hard pearlite phase dispersed and distributed in the base material, It is clear that uneven wear is likely to occur because of poor conformability. As described above, the sintered oil-impregnated bearing of the present invention has excellent compatibility with the rotating shaft that is a mating material, and also has excellent self-lubricating property. It exhibits excellent wear resistance over a long period of time.

[Brief description of drawings]

FIG. 1 is a porous Cu-F constituting a sintered oil-impregnated bearing of the present invention.
It is a structure expansion copy figure of an e-Sn system sintered alloy.

FIG. 2 is a porous Cu-F constituting a sintered oil-impregnated bearing of the present invention.
It is a structure expansion copy figure of an e-Sn system sintered alloy.

FIG. 3 Porous Cu—Fe forming a conventional sintered oil-impregnated bearing
It is a structure expansion copy figure of-Sn system sintered alloy.

FIG. 4 is a schematic front view showing a radial friction tester.

[Explanation of symbols]

 1 Support jig 2 Sintered oil-impregnated bearing 3 Rotating shaft 4 Ball bearing 5 Load cell

Claims (2)

[Claims] 1. By weight%, Fe: 40-60%, Sn: 0.1-5%, C: 0.1-2%, S: 0.05-1%, B: 0.01-0. 0.5% by weight, the balance consisting of Cu and unavoidable impurities, a ferrite phase dispersedly distributed on the base of a Cu-Sn alloy, and free graphite grown with the S component as a nucleus in the ferrite phase. Cu-F having a structure in which the B component is dispersed and distributed, and the B component is distributed along the surface of the ferrite phase and along the crystal grain boundaries, and the porosity is 10 to 30%.
A wear-resistant sintered oil-impregnated bearing having a low opponent attack characteristic, which is characterized by comprising an e-Sn sintered alloy. 2. By weight%, Fe: 40 to 60%, Sn: 0.1 to 5%, C: 0.1 to 2%, S: 0.05 to 1%, B: 0.01 to 0. 0.5%, molybdenum sulfide: 0.5 to 2%, the balance Cu
And a composition consisting of unavoidable impurities, a ferrite phase is dispersed and distributed in the base material of the Cu-Sn alloy, and free graphite grown with the S component as a nucleus is dispersed and distributed in the ferrite phase, and the surface of the ferrite phase is further distributed. And the B component is distributed along the grain boundaries,
Porous Cu-F having a structure in which molybdenum sulfide is distributed at the interface between the base and the ferrite phase, and a porosity of 10 to 30%
A wear-resistant sintered oil-impregnated bearing having a low opponent attack characteristic, which is characterized by comprising an e-Sn sintered alloy.