JP3214862B2 - Self-lubricating sliding material and lubrication-free bearing using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-lubricating sliding material excellent in mechanical strength and a non-lubricated bearing obtained by using the same.

[0002]

_2. Description of the Related Art A solid lubricant such as graphite, MoS ₂ , WS ₂ , BN, etc., and a metal powder such as Fe, Cu, Al, etc. are mixed, molded, and sintered to disperse the solid lubricant in a metal matrix. It is known that a sintered body can be obtained. In a bearing using this sintered body, during sliding, the solid lubricant in the sintered body is exposed and supplied on the sliding surface of the bearing, and is spread in a film form to provide slidability to the shaft. Is done.

[0003] Therefore, it has been noted that even if oil such as grease is not supplied to the sliding surface, in other words, it can be used as a sliding material without lubrication, such a self-lubricating sliding material has been noted. For example, various techniques have been proposed as disclosed in JP-A-62-196351.

[0004]

However, the conventional self-lubricating sliding material has a problem that when the sliding property is enhanced, the mechanical strength is remarkably deteriorated in inverse proportion.

[0005] The reason is that, in a sliding material used without lubrication, the minimum sliding characteristics cannot be obtained unless at least 30 vol% of solid lubricant is contained in the matrix. When the content is more than 30 vol%, the strength of the matrix becomes 1/5 or less.

Therefore, it has been found that a conventional bearing using a self-lubricating sliding material as a whole is extremely brittle and has low strength, and is not suitable for use under a high surface pressure. The above-mentioned Japanese patent
The self-lubricating sliding material disclosed in Japanese Patent Application Laid-Open No. 62-196351 is not yet sufficient in terms of desired strength as well as slidability.

Furthermore, when used under high surface pressure such as construction machines, there is a high possibility that abnormal wear accompanied by pitching will occur, and further improvement in strength is required. In addition, conventional self-lubricating sliding materials have, for example, a particle size of 1 as a solid lubricant.
It was manufactured using graphite of about 00 μm to 1 mm and iron powder having an average particle size of 100 μm as metal powder. Therefore, the particle size of the metal powder blended in the solid lubricant is relatively large, and the solid lubricant is soft, so the solid lubricant is deformed during molding in the manufacturing process, and as a result, the matrix of the sintered body and the solid lubricant are deformed. There is a problem that it is unavoidable that a gap, that is, a so-called notch is formed between the agent and the agent.

As a result, stress concentrates on the notch,
This has been a cause of lowering the mechanical strength of the sliding material.
Therefore, an object of the present invention is to provide a self-lubricating sliding material with further improved mechanical strength and a lubrication-free bearing using the same.

[0009]

In order to achieve the above-mentioned object, the present invention uses a fine iron powder having a particle size of 45 μm or less as a means for preventing the occurrence of notches which cause a decrease in mechanical strength. It was decided to.

That is, in the non-lubricated bearing of the present invention, the sliding material forming the sliding portion is a solid lubricant containing 10 to 80 vol.
%, The iron powder for forming the matrix of the sintered body having a particle diameter of 45 μm or less,
The iron powder is a self-lubricating sliding material formed so as to surround the outer periphery of the solid lubricant in a spherical shape without any gap, and the sintering does not include the solid lubricant on the non-sliding surface side of the sliding portion. The body is arranged.

The iron powder having a particle diameter of 45 μm or less, which is the largest feature of the grease-free bearing of the present invention and is applied to the matrix forming portion, may be an alloy powder mainly composed of iron.
In order to obtain a fine powder having a particle size of 45 μm or less, a powder produced by, for example, a spray method is sieved through a 350 mesh sieve.
The method may be Re adopted the like.

As the solid lubricant, graphite, MoS ₂ , WS ₂ ,
Any of BN and the like can be used, preferably 30 μm to 10 μm.
What is granulated to about 00 μm is used. Also, graphite coated with water glass can be used. The appropriate amount of the solid lubricant is 10 to 80 vol% of the sintered body. If the amount is less than this, stable lubrication as an oil-free sliding material cannot be obtained,
If the amount is too large, the strength cannot be secured.

The lubrication-free bearing of the present invention is characterized in that the sliding portion is made of a sliding material and a high-strength sintered body having no lubricant on the non-sliding surface side of the sliding portion for reinforcing the sliding portion. I decided to arrange. The thickness of the sliding part should be 0.5 to 2 in consideration of slidability and strength.
It is preferably in the range of mm. The metal powder used for producing the high-strength sintered body may be an ordinary metal powder, which may be the same as or different from the metal powder serving as the matrix of the sliding material.

The non-greasing bearing of the present invention is made of a sintered body and is porous, and has pores of about 10 to 25 vol% inside. Infiltrating the pores with an infiltrating agent is effective in improving strength and wear resistance. As the infiltrant, for example, a Cu-Sn compound containing 15 to 40 wt% of Sn is mainly used. A Cu-Sn based infiltrant is usually used, and a mixture of Pb and 3 to 40% by weight is also preferably used.

[0015]

FIGS. 1 (a) and 1 (b) are views showing a state in which a solid lubricant and a metal powder are mixed and molded in order to produce a sliding material. Is used to compare the case where coarse metal powder is used with the case where coarse metal powder is used.

First, when a coarse metal powder is used as shown in FIG. 1 (a), a large gap between the solid lubricant 1 and the metal powder 2 where the solid lubricant 1 and the metal powder 2 come into contact with each other, that is, a notch is formed. It turns out that exists. When a notch occurs, stress concentrates on that portion, and the notch significantly reduces the strength. Further, at the time of sliding, wear progresses from the notched portion.

On the other hand, FIG. 1 using fine metal powder
In the case (b), the metal powder 2 surrounds the solid lubricant 1 in a spherical shape close to a spherical shape with no gaps along the outer periphery. As a result, the occurrence of gaps between the powders that cause the notches is small, and the above-described inconvenience is avoided.

Another effect of using fine particles is that the number of metal powders increases for the same weight. This increases the probability that the metal powder is interposed between the solid lubricants, and prevents the solid lubricants from adhering to each other. As a result, the dispersibility of the solid lubricant is improved. As described above, bearings using sliding materials with few notches and good dispersibility of solid lubricant on the sliding surface have abrasion resistance and strength, especially flexural strength, larger than those of conventional bearings. Be improved.

[0019]

Therefore, according to the present invention, a high-strength sliding material capable of sufficiently withstanding abnormal wear accompanying pitching when using a non-greasing bearing such as a construction machine under a high surface pressure, and a sliding material having the same. The used bearing will be provided.

[0020]

Next, an embodiment in which the present invention is applied to a bush of a bearing will be described. The bush of this example was obtained by the following steps.

[0021] Sieving Atmel 4600 (Kobe Steel,
Fe-2Ni-0.5Mo) alloy powder was sieved to separate fine particles having a particle size of 45 μm or less.

Mixing Fine particles of Atmel 4600 obtained as a powder component of the inner diameter layer,
P and C were used in the composition shown in Table 1, and 40 vol% of granulated graphite was further added to the total amount thereof and mixed with a V-type mixer. As powder components of the outer diameter layer, coarse particles of Atmel 4600, P and C, which were not sieved, were similarly mixed by a V-type mixer.

Forming First, two-layer powder feeding was performed using a two-layer powder feeding jig. In this two-layer feeding, the forming mold was partitioned into an outer diameter portion and an inner diameter portion by a partition plate, and the outer diameter portion was filled with the outer diameter layer powder, and the inner diameter portion was filled with the inner diameter layer powder. After filling, pull up the partition plate and CIP
Press molding was performed. The molding pressure was 4 t / cm ² .

The compact obtained by sintering is placed in an ammonia decomposition gas atmosphere for 10 minutes.
Sintering was performed at a sintering temperature of 50 ° C.

Infiltration Infiltration was performed at 1050 ° C. in an ammonia decomposition gas atmosphere using Cu-20Sn as an infiltrant.

Further, as Comparative Examples 1 and 2, bushes were prepared in the same manner as in the examples with the component compositions shown in Table 1. In addition,
In Comparative Example 1, the infiltrant was infiltrated in the same manner as in the Example, but in Comparative Example 2, no infiltration was performed.

Next, a wear test and a bending strength test were performed on the bushes of the example and comparative examples 1 and 2. In the wear test, the bush was attached to the bearing tester shown in FIG. 2 and the shaft 10 was swung under the test conditions according to the cycle shown in FIG.
The amount of wear of the sliding surface of the test bush 11 due to the swing of 10 was measured. In addition, 12 is a movable housing, 13 is a thermocouple, and W is a predetermined additional pressure. FIG. 4 shows the results of the wear test, and FIG. 5 shows the results of the bending strength test.

FIG. 6 shows micrographs of the metal structure of the inner diameter layer of the bush of Example (a) and Comparative Example 1 (b).
Comparison of these photographs shows that Example 1 (a) shows Comparative Example 1
The shape of graphite was closer to a sphere than (b), and it was confirmed that each graphite was well dispersed.

[Table 1]

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are schematic diagrams showing states of a solid lubricant and a metal powder during molding.

FIG. 2 is a schematic view of a bearing tester used for a wear test.

FIG. 3 is a graph showing test conditions of a wear test.

FIG. 4 is a graph showing the relationship between the number of loads and the amount of wear.

FIG. 5 is a graph showing bending strength.

FIGS. 6A and 6B are micrographs showing the metal structure of a sliding material.

[Explanation of symbols]

 1 solid lubricant 2 metal powder

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI F16C 33/12 F16C 33/12 A (56) References JP-A-2-107773 (JP, A) JP-A-1-201435 (JP, A JP-A-63-297876 (JP, A) JP-A-2-290905 (JP, A) JP-A-61-505 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 38/00 304 B22F 3/26 B22F 5/00 C22C 29/00 C22C 32/00 F16C 33/12

Claims (2)

(57) [Claims] A sliding material forming a sliding portion is a sintered body containing 10 to 80 vol% of a solid lubricant, and iron powder for forming a matrix of the sintered body has a particle diameter of 45 μm.
m, and is a self-lubricating sliding material formed by molding the iron powder so as to surround the outer periphery of the solid lubricant in a spherical shape without any gap. A non-lubricated bearing comprising a sintered body that does not contain a lubricant. 2. An infiltrating agent for improving the strength characteristics of a sintered body is formed during drilling of the sintered body forming the sliding portion and the sintered body disposed on the non-sliding surface side of the sliding portion. The grease-free bearing according to claim 1, wherein the bearing is infiltrated.