JPS5819413A - High strength copper-base sintered bearing having high oil content and showing superior performance in high load region - Google Patents

Abstract

PURPOSE:To obtain a high strength copper-base sintered bearing having a high oil content and showing superior performance n a high load region by adding a specified amount of Fe to a Cu-Sn-P material. CONSTITUTION:A high strength copper-base sintered bearing material having a high oil content is composed of 4-11wt% Sn, 0.2-1.0% P, 5-20% Fe and the balance Cu with inevitable impurities. To the composition may be added 1-10% of >=1 kind of lubricating components such as graphite, molybdenum disulfide or Pb. By the composition, hard Fe particles in a bearing prevent the plastic flow of the sliding surface, and superior bearing performance is shown in a high load region.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-strength, high oil-impregnated sintered bearing that is manufactured by a powder metallurgy method and exhibits excellent performance in a high load area.

Generally, sintered bearings are used by impregnating oil into the pores present in the structure of a porous sintered body.

Since the bearings are used without oil, especially under harsh operating conditions, the oil will gradually oxidize and be consumed, eventually leading to a decline in bearing performance. This will cause seizure and make it unusable. For this reason, the larger the amount of oil impregnated in a sintered bearing, that is, the oil content, the better, but if the oil content is increased, the radial crushing strength will decrease, which is undesirable.
The standards also specify minimum values for oil content and radial crushing strength.

Conventionally, bronze-based sintered bearings have been known as such sintered bearings, and are also specified in the JIS standard (composition -8n).
: 8-11%, C: 3% or less, other 20.5%
Hereinafter, Cu: residue, oil content: 18 volume or more, and radial crushing strength: ltskg/- or more are specified. ), such conventional bronze-based sintered bearings have an oil content and radial crushing strength that meet the JIS regulations, but when used under severe operating conditions, they do not meet the requirements due to insufficient oil content. The bearing life was not shown in each case. Therefore, in order to lower the coefficient of friction on the boundary lubrication surface during operation, the conventional bronze-based sintered bearings are made to contain 0.5 to 20% of lubricating components such as graphite, molybdenum disulfide, PB, and PB gold alloy. Bronze-based sintered bearings have been developed that can withstand harsh operating conditions.
In the case of this bronze-based sintered bearing, if a large amount of graphite or molybdenum disulfide is contained, the matrix will be fragmented, resulting in a decrease in strength.In order to compensate for this decrease in strength, increasing the pressure during green compact compaction will result in an oil-impregnated bearing. Similarly, when the sintering temperature is increased, the lubricating components are decomposed and
In addition, if PB and PB gold alloys are contained, if the sintering temperature is increased, the liquid phase sintering phenomenon will become active, leading to an increase in density and a pore sealing phenomenon (open pores that become oil-impregnated pores). There were problems such as a phenomenon in which oil content decreased, leading to a decrease in oil content.

Therefore, the same applicant previously filed Japanese Patent Application No. 53-38820 (Japanese Unexamined Patent Publication No. 54-131528; hereinafter referred to as the "prior invention") to improve the lifespan of bronze-based sintered bearings as described above. In order to withstand long-term use even under such conditions, we added P: 0.2 to 1 to conventional bronze-based sintered bearings containing 8 to 11% Sn (hereinafter referred to as weight percent).
．． We have proposed a sintered oil-impregnated bearing containing '/%. In this way, when conventional bronze-based sintered bearings contain P, Cu (Cu)
On the one hand, the alloying of Sn into the IJ lux is promoted, and on the other hand, the solid solution of P with Sn in the Cu matrix has the effect of reducing the solid solubility of Sn in Cu, resulting in a strong Cu-8n- As P alloy is formed and the amount of liquid phase increases relatively, the matrix expands and the Sn outflow pores also become coarser, increasing the porosity ( This made it possible to obtain a sintered bearing that has both excellent radial crushing strength and high oil content.

As described above, the sintered oil-impregnated bearing of the prior invention can be used under more severe conditions than the conventional bronze oil-impregnated bearing.
Considering that the bearing is operated under a high load of about d or more, it was found that there is a slight problem in that a sufficiently satisfactory bearing performance cannot be obtained.

From the above-mentioned viewpoint, the present inventors have conducted repeated research to improve the bearing performance of the Cu-3n-P oil-impregnated bearing in the prior invention in the high load region, and have found the following (a) to
We have come to the conclusion shown in (C). That is, (a) The reason why it is difficult for the Cu-8n-P oil-impregnated bearing in the prior invention to exhibit sufficiently satisfactory bearing performance when operated in a high load region is that the sliding surface undergoes plastic flow and oil-impregnation occurs. This is because it crushes the pores that are essential to bearings.

(b) When a predetermined amount of Fe is contained in the Cu-8n-P oil-impregnated bearing material of the prior invention, the Fe particles, which are harder than the matrix, prevent plastic flow on the sliding surface, resulting in particularly A sintered bearing with excellent bearing performance in a high load area can be obtained.

(C) When the bearing material further contains one or more lubricating components such as graphite, molybdenum disulfide, PB, and PB alloy, the bearing performance is further improved.

Therefore, this invention was made based on the above findings, and includes a sintered bearing containing Sn: 4 to 11%, P: 0.2 to 1.0%, Fe: 5 to 20%, and further comprising: If necessary, one or more of the lubricating components: The usual content of 1 to 10%, and the remainder: Cu and unavoidable impurities. It is characterized by its high strength and high oil content, which provides excellent bearing performance.

In addition, as mentioned above, the lubricating components that are the constituent components of the sintered bearing of this invention include graphite, molybdenum disulfide,
PB, PB gold alloy, or any lubricating component conventionally used as this type of lubricating component can be used, and the amount added is the same as that conventionally used in this type of bearing, that is, 1 to 1. 10 pieces is enough.

Further, the purpose of sintering the bearing can be sufficiently achieved under the conditions of the powder metallurgy method that has been generally employed.

In the sintered bearing of this invention, the Sn content is 4 to 11%.
This is limited to S for bronze sintered oil-impregnated bearings according to the JIS standard.
According to the n content of 8 to 11%, the lower limit is 4%.
The reason for increasing the strength to the lower side is that the strength can be supplemented by adding Fe component. In addition, the P content was reduced to 0.2
The reason for limiting the content to ~1.0% is that if the content is less than 0.2%,
The desired improvement effect on strength and oil content could not be obtained;
This is because if the content exceeds 0%, it will react with the Fe component to form a very hard and brittle Fe3P compound, impairing bearing characteristics. Furthermore, the reason why the Fe content is limited to 5 to 20% is that a Fe content of less than 5% prevents plastic flow on the bearing sliding surface and exhibits excellent bearing performance in high load areas. On the other hand, if it exceeds 20%, the proportion of Fe particles on the sliding surface increases too much, which damages the rotating shaft, making it impossible to obtain the desired improvement effect.

Next, the sintered bearing of the present invention will be explained using examples.

Example particle size: 1 particle size of electrolytic Cu powder of 100 mesh or less: 3
Atomized Sn powder of 50 mesh or less, and atomized Cu-P alloy (C
u-8,4%P eutectic alloy) powder, and average particle size 5
μm carbonyl Fe powder is prepared, these raw material powders are blended and mixed to have the final component composition shown in Table 1, and the resulting mixed powder is
A green compact is molded at ~3 ton/c+7, and the green compact is sintered by holding it at a temperature of -700 to 800°C for 30 minutes in a hydrogen atmosphere. Sintered oil-impregnated bearings of the prior invention (hereinafter referred to as "prior bearings") and compositions in which any of the P, Sn, and Fe contents are higher or lower than the range of the present invention (Table 1) Comparative sintered oil-impregnated bearings (hereinafter referred to as comparative bearings) 1 to 6 having component contents marked with * outside the range of the present invention were manufactured, respectively.

Next, bearing performance tests were conducted on the resultant bearings of the present invention, the 9° preceding bearings, and the comparative bearings 1-6. For the test, oil No. A465 was impregnated, and the characteristics of this oil were a specific gravity of 0.91. Kinematic viscosity (cs
t) is 12.2° at 98.8°C and 63.0° at 37.8°C.
．． It showed 32500 at -40.0°C.

The test operation was performed under a load P: 20 kg/cI/l, which is considered to be relatively severe for a Cu-based oil-impregnated bearing, a rotation speed N: 400 Or, p, m, (peripheral speed y: 1
00m/am.

pv: zoookg/cII-m/min) for 5 hours, and the coefficient of friction was measured. In addition, the degree of collapse of the pores on the sliding surface of the bearing and the degree of scratches on the rotating shaft were observed after the test. Note that the rotating shaft was made of carbon steel with a hardness of about HRB 90. The measurement results are also shown in Table 1.

In Table 1, the condition of the bearing sliding surface and the condition of scratches on the rotating shaft are evaluated on a four-level scale, with the best being marked O, and the good being marked ○.
A slight defect is indicated by a Δ mark, and a defect is indicated by an X mark.

As is clear from the results shown in Table 1, the bearing of the present invention contains a predetermined amount of Fe in the preceding bearing;
Even during operation under severe high loads as described above, there was hardly any vibration on the sliding surfaces, and the condition of scratches on the rotating shaft was also very good. Therefore, the friction coefficient is 0.02 to 0.
Excellent performance was demonstrated in the 04 range. However, comparative bearings 1, 3. Bearings 5 and 5 had a low content of Sn, P, or Fe, and plastic flow occurred on the sliding surface (relatively pores remained in comparative bearing 5).

Therefore, although the degree of damage to the rotating shaft was small, the coefficient of friction increased.

On the contrary, comparative bearings 2, 4. and 6 is Sn, P.

Or, the Fe content is too high, and although the plastic flow on the sliding surface is relatively small, the hard layer (Cu-, Sn δ phase, Cu1oSQ's, Fe3P, Fe2P, and F
The rotating shaft was deeply damaged by the particle itself, and the coefficient of friction increased considerably.

As mentioned above, the bearing of the present invention has characteristics that allow it to exhibit excellent performance in high load areas.

Applicant: Mitsubishi Metals Corporation Agent Tomi 1) Kazuo

Claims (2)

[Claims] (1) Contains 8n: 4 to 11%, P: 0.2 to 1.0%, Fe: 5 to 20q6, and has a composition consisting of Cu and unavoidable impurities: balance (more than % by weight) A high-strength, high oil-impregnated sintered bearing that exhibits excellent performance in high-load areas. (2) Contains Sn: 4 to 11%, P: O12 to 1.0%, Fe: 5 to 20%, and further contains 1 to 10% of one or more lubricating components, A high-strength, high-oil-containing sintered bearing that exhibits excellent performance in a high-load region, characterized by having a composition consisting of CU and unavoidable impurities: (more than % by weight).