JPH02142920A - Lubricating oil impregnated metal powder sintered bearing and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a lubricating oil impregnated metal powder sintered bearing with small friction and abrasion under the wide using condition by heating the sintered bearing, and thereafter, dipping he bearing in the lubricating oil in which the solid lubricant is uniformly dispersed, and uniformly dispersing he solid lubricant having the powder diameter smaller than the diameter of the capillary holes in the bearing sintered material. CONSTITUTION:The solid lubricant is added in the lubricating oil, and the dust powder of the solid lubricant is dispersed uniformly in the lubricating oil with the ultrasonic wave or a ball mill. After heating the burning-processed bearing, it is dipped in the lubricating oil for 10 60 minutes. The lubricating oil permeated into holes of inside of the bearing sintered material is moved through the capillary holes connecting the holes each other. The dust powder of the solid lubricant is uniformly dispersed in the lubricating oil, and since the diameter of the powder is smaller than the diameter of the capillary holes, the dust powder is moved together with the movement of the lubricating oil and is oozed out to the bearing surface. Since the solid lubricant stands under the condition that the contacting pressure is high so as to eliminate the generation of the break of he lubricant film, the friction of the contacted interface is small under the condition of the boundary lubrication, and the baking caused by the break of the oil film is eliminated.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a sintered oil-impregnated bearing, specifically a sintered body containing metal powder or non-metal powder as a main component, or a sintered body containing metal powder and lubricating non-metal powder as main components. The present invention relates to a lubricious sintered oil-impregnated bearing in which a sintered body as a component is impregnated with lubricating oil, and a method for manufacturing the same.

(Conventional technology) Conventional sintered oil-impregnated bearings are made by adding Mo5 (molybdenum disulfide), WSZ (tungsten disulfide), or BN (boron nitride) to a mixed material such as Cu-3n or Fe-Cu. ), graphite, carbon blank, acetylene black, and other solid lubricants and antioxidants are used as the raw material powder, and the mixed raw material powder that is uniformly blended with them is compacted, sintered, and then sintered. This is a bearing whose body is impregnated with lubricating oil.

In sintered oil-impregnated bearings, the impregnated oil and residual air inside the empty tag expand due to the frictional heat generated as the shaft rotates, and there is also a pump action in which oil is blown into the sliding surface as the shaft rotates.
The lubricating oil held in the pores of the sintered body oozes out, forming a lubricating oil film on the contact interface. Since sintered oil-impregnated bearings exhibit self-lubricating properties as described above, they are widely used as so-called oil-less bearings that do not require external oil supply.

[Problem to be solved by the invention]

However, in the conventional sintered oil-impregnated bearings mentioned above, when the shaft rotates at high speed, the oil that seeps into the contact interface tends to form a fluid lubricant film by entraining the shaft, so there is little friction and wear, and the shaft Movement is stable. However, when the shaft is rotating at a low speed, the state of the contact interface is mainly boundary lubrication, which has the disadvantage that frictional wear is large and the movement of the shaft becomes unstable. Particularly when the shaft performs intermittent, swinging, reciprocating motion, etc., friction and wear increase significantly.

The present invention is suitable for low-speed rotation, high load, intermittent, rocking motion, where the oil film strength is extremely weak and there is a lot of contact between minute convex portions on the bearing surface.
A lubricious sintered oil-impregnated bearing that eliminates the above conventional drawbacks under conditions such as reciprocation, and has low friction and wear and smooth sliding even under a wide range of usage conditions such as low and high speed rotation, intermittent, rocking, and reciprocation. The present invention provides a method for manufacturing the same.

[Structure of the invention]

The present invention is a sintered oil-impregnated bearing characterized in that a solid lubricant having a particle size smaller than the diameter of the pores inside the bearing sintered body is uniformly dispersed in lubricating oil.

The manufacturing method involves adding a solid lubricant to lubricating oil and uniformly dispersing it using ultrasonic waves or a ball mill.After heating the sintered bearing, it is then added to the lubricating oil in which the solid lubricant is uniformly dispersed. a step of adding a solid lubricant to the lubricating oil and uniformly dispersing it using ultrasonic waves or a ball mill; and a step of degassing the sintered bearing in a vacuum and then removing the solid lubricant. This method includes a step of immersing the solid lubricant in a lubricating oil in which the solid lubricant is uniformly dispersed.

[Effect]

The lubricating oil that has permeated the pores inside the bearing sintered body is transferred and assisted through the capillary pores that connect the pores. Fine solid lubricant powder is uniformly dispersed in the lubricating oil, and its particle size is smaller than the diameter of the capillary pores, so as the lubricating oil moves, it moves through the capillary pores and seeps out onto the bearing surface. Solid lubricants can withstand high contact pressure and do not cause the lubricant film to break, so even in boundary lubrication conditions, the friction at the contact interface is small, causing the oil film to break and seize to occur. Things don't come easily.

[Examples] (]) The method for manufacturing a lubricating sintered oil-impregnated bearing of the present invention will be described below based on Examples.

(1) As the raw material powder, conventional metal powder or non-metal powder is used, and the addition of auxiliary agents and the uniform mixing method also follow conventional methods. In the case of Cu-3n bearings, the proportion of Sn is 5 to 15% and the solid lubricant is 0 to 5%, and in the case of FeCu bearings, the proportion of Cu is 0 to 2.
5%, Pb 0 to 15%, and solid lubricant 0 to 5%. The powder particle size is O.1 to 100 μm, and the solid lubricant is generally uncoated, but is coated with metal if necessary.

(1)) After uniformly mixing the powder, it is filled into a mold and compressed under pressure to form a green compact.

(iii) Alloying, sintering, and porosity are simultaneously performed by firing the powder compact. The firing temperature and firing time are appropriately selected depending on the powder raw material, particle size, compaction density, shape, etc. The same applies to the selection of firing atmosphere such as hydrogen gas, ammonia decomposition gas, nitrogen gas, argon gas, etc., and vacuum firing.

(iv) The fired sintered body may be used as a bearing without being processed, but in order to adjust the shape and surface roughness, sizing, coining, and cutting are required for -E. give

(v) As a method for uniformly dispersing fine powder solid lubricant in lubricating oil, the solid lubricant is added to lubricating oil and stirred using ultrasonic waves, or mechanical stirring using a ball mill is used. use The particle size of the solid lubricant is further finely pulverized.
The latter method is preferable if you want to do so.

(vi) The step of impregnating the sintered bearing with the lubricating oil in which the solid lubricant is uniformly dispersed is performed by
A method in which the bearing is heated to a temperature of (Act).

(2) In order for the solid lubricant powder to be impregnated inside the bearing, it must be smaller than the diameter of the pores of the bearing. The size of the pores and pores that exist inside a sintered bearing varies depending on the raw material, powder particle size of the raw material, firing conditions, etc. It is useful to know the relationship between the particle size of the solid lubricant and the impregnation rate (the rate at which the solid lubricant is impregnated in the lubricating oil) for bearings. Figure 1 shows that the particle size is 0. WS with particle sizes of 1 μm and 2.2 μm, and MoS with particle sizes of 9.3 μm, 0.1 am, and 10 pm.

Five types of solid lubricants are each mixed with high grade lubricant base oil (IS
The impregnation rate is shown when the sample is uniformly dispersed in O220) and then impregnated into a Cu-10%Sn sintered bearing having a porosity of 13% by a vacuum method. Solid lubricants with a particle size larger than 0.7 μm are not impregnated, but at 0.3 am, about 40%
,0. It can be seen that 100% impregnation is achieved in ll1m.

(3) Figure 2 shows the relationship between contact load and friction coefficient μ for a bearing according to the present invention (b) and a conventional bearing in which solid lubricant is not dispersed in lubricating oil (a). be. The tested product (b) is raw material powder Cu powder (average particle size 50 tIm) 90wt
Sn powder (average particle size 50μm) 10wt% Firing conditions Firing in a hydrogen gas atmosphere at 400°C and 790°C for 30 minutes each Porosity 13% Impregnation oil WS*(
Average particle size: 0.1 μm) was uniformly dispersed at 1.5 wt%.

In (a), high-purity base oil (ISO220) was used as the impregnating oil. The friction coefficient μ is the sliding friction between two planes with S45C carbon steel using a precious wood friction tester (sliding speed 10 cts/sec).
s friction time (1 hour, room temperature). Conventional product (
Regarding b), when the contact load is 1 kg/cd, μ has a minimum value of 0.27 when it is 0.30.3 kg/cd, but the seizure load (the value of the load where μ increases rapidly) is about 6.
kg/cd, and if it exceeds that, seizure will occur. For the tested product (b), μ is the contact load of 1 to 13 kg/cd.
During the period, the low value of 0.08 was maintained, and the weight was 13 kg.
/cd, and the number of seizures is approximately 18 kg/c-. This decorative product has an extremely smaller μ than conventional bearings, has little change due to contact loads, and can withstand high contact loads.

FIG. 3 shows the relationship between contact load and bearing wear rate Ws for each of the bearings (a) and (b) above. Conventional product (
In case a), the wear rate increases with steep slope as the contact load increases (7X l O-@am at 1kg/cd).
7 kg, 8 X 10-'fflI at 6 kg/c4
n” 7kg), and the contact load of the implemented product (B) is 15kg.
/c- (8X I O-'am" 7kg) and the wear rate is small. Therefore, the life of this decorative product is extremely long compared to conventional products.

FIG. 4 shows the relationship between the concentration of WS2 contained in the impregnated oil and the seizure load of the actual product. Wsz month, 5wt%
Up to this point, as the amount of solid lubricant increases, the seizure load also increases, but at a concentration of 1.5 wt% or more, the seizure load has a saturated value.

Therefore, it can be seen that although the solid lubricant has the effect of the present invention even if the concentration of the solid lubricant is small, the presence of 1.5 wt% provides a sufficiently good effect.

(4) FIG. 5 shows the relationship between load and FRW# coefficient μ coefficient for other implemented products. The tested product (d) was made of raw material powder: Fe (average particle size: 50 μm) 80 wt% Cu powder (average particle size: 50 μm): 20 wt% Firing conditions: Firing at 1000°C for 30 minutes in an ammonia decomposition gas atmosphere Porosity: 20% Impregnating oil: High WoSz in purity base oil (ISO220)
(average particle size 0.3 μm) 1. Owt% was uniformly dispersed.

In (c), high-purity base oil (ISO220) was used as the impregnating oil.

FIG. 6 shows the relationship between the contact load and the wear rate Ws for each of the bearings (c) and (d) in FIG. 5. Implemented product (
It can be seen that d) has extremely superior properties compared to the conventional product (c).

(5) Figure 7 shows the product manufactured under the following conditions (
The relationship between the load and the coefficient of friction μ is shown for (f) and (g).

Raw material powder Fe powder (average particle size 50μm) 50wt% Cu powder (average particle size 50μm) 5Qwt% Firing conditions 1) Firing in an ammonia decomposition gas atmosphere at 00°C for 30 minutes Porosity 35% Impregnated oil product (to) High Carbon black (average particle size 0.03 μm) was uniformly dispersed at 0.5 wt% in a pure base oil (ISO220).

Implemented product (Japan) 1.5 wt% of carbon black (average particle size 0.03 am) and 1.5 wt% of WS (average particle size 0°1 μm) were uniformly dispersed in high purity base oil (ISO220). .

(E) is a high purity base oil (IS0220) for the above impregnating oil.
was used. FIG. 8 shows the relationship between the contact load and the wear rate Ws for each of the bearings (E), (F), and (G) in FIG. It can be seen that the implemented products (f) and (g) have extremely superior properties compared to the conventional product.

〔Effect of the invention〕

Since the present invention has the above-described structure and method, it eliminates the above-mentioned conventional drawbacks and has stable and smooth sliding with low friction and wear even under conditions such as low rotation, high load, intermittent, rocking, and reciprocation. We were able to supply a sintered oil-impregnated bearing with a long lifespan.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between particle size and impregnation rate of the solid lubricant in the present invention, FIGS. 2, 5, and 7 are diagrams showing the relationship between contact load and friction coefficient of products implementing the present invention, Figure 3, Figure 6,
FIG. 8 is a diagram showing the relationship between contact load and wear rate of the product according to the present invention, and FIG.
FIG. 3 is a diagram showing the relationship between degree and seizure load. Okada armpit - 1° Figure 4 Figure 51 degrees (wt%) Figure 8 Load t (kcVc rise) Figure 2 Figure m t (kg/crn”) Figure 6 Figure 7: /c wake up)

Claims (3)

[Claims] (1) A sintered oil-impregnated bearing characterized in that a solid lubricant having a particle size smaller than the diameter of the pores inside the bearing sintered body is uniformly dispersed in lubricating oil. (2) The process of adding solid lubricant to lubricating oil and uniformly dispersing it using ultrasonic waves or a ball mill, and heating the sintered bearing and then adding it to lubricating oil in which solid lubricant is uniformly dispersed. The method for manufacturing a sintered oil-impregnated bearing according to claim 1, comprising the step of soaking for 10 to 60 minutes. (3) The process of adding a solid lubricant to the lubricating oil and uniformly dispersing it using ultrasonic waves or a ball mill, and degassing the sintered bearing in a vacuum, and then dispersing the solid lubricant uniformly. The method for manufacturing a sintered oil-impregnated bearing according to claim 1, comprising the step of immersing the bearing in lubricating oil.