JPH1113801A - Frictional material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat dissipation, by fusing specified quantity respectively of metallic particles and resin particles using heat source, in a frictional material used for a clutch and others of an automobile or others, and by inter-combining metallic particles, resin particles, or a metallic particle and a resin particle to form a pore with specified volume. SOLUTION: This frictional material is composed of 30-80 vol.% of metallic particle M, such as high strength brass, alloy steel, tin bronze, aluminum alloy, or titanium, and 10-60 vol.% of resin particle P, such as polybutyleneterephthalate, nylon, polyketone, or polyacetal. Furthermore, both particles are fused or semi-fused by a heat source, metallic particles M, resin particles P, or metallic particle M and resin particle P, respectively, are chemically and mechanically inter-combined, and a frictional material with a pore H of 10-40 vol.% is provided. In this case, the grain diameter of used metallic particle M is 2-200 μm, and the grain diameter of resin particle P is 30-300 μm. Therefore, each particle can be evenly dispersed, and characteristic as frictional material is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material, and more particularly to a friction material for a clutch for transmitting a drive from a prime mover such as an automobile to a transmission or a brake for stopping the drive.

[0002]

2. Description of the Related Art Conventional wet friction materials are prepared by blending natural pulp fibers such as cotton and hemp with fillers such as diatomaceous earth and silica, and friction modifiers such as graphite and resin particles, and adding a papermaking chemical to wet friction materials. A paper friction material obtained by impregnating a thermoset resin such as phenol into a special paper thus formed and then drying and curing the same is used. The paper friction material is widely and generally used as an excellent material because it can maintain a high friction coefficient stably over a wide range of sliding speeds due to being a porous elastic material.

[0003]

However, in the prior art, the base material is an organic fibrous material such as pulp, and the heat resistance is low. There was a problem that it increased. In order to solve this problem, as shown in Japanese Patent Application Laid-Open No. 9-104763, the heat resistance is improved by mixing a filler or the like. Could not get.

[0004] Further, as a friction material having excellent heat resistance,
A sintered friction material whose base material is made of metal is generally known, but has a problem that the friction coefficient is lower than that of the paper friction material, and the friction coefficient decreases as the sliding speed increases.

[0005] The present invention has solved the above problems,
An object of the present invention is to provide a wet friction material having excellent heat resistance and capable of stably maintaining a high coefficient of friction in a wide range of speed.

[0006]

Means for Solving the Problems In order to solve the above technical problems, the technical measures taken in claim 1 of the present invention are as follows.

[0007] 30 to 80% by volume of metal particles and resin particles 10
６０60% by volume, and the two particles are melted or semi-molten by a heat source to chemically and mechanically bond the metal particles, the resin particles, or the metal particles and the resin particles. The friction material is characterized in that pores of 10 to 40% by volume are formed.

[0008] With this configuration, since the base material is made of metal, there is no thermal deterioration and the heat dissipation can be improved, so that excellent heat resistance can be obtained. Further, by bonding the particles together, pores can be formed between the particles, and by further mixing resin particles, the friction material itself can be made to be an elastic body. As a result, the oil film on the sliding surface between the friction material and the counterpart can be quickly removed, and the contact area of the sliding surface can be increased and uniform contact can be obtained by elastic deformation. Can be stably maintained in the area.

[0009] When the content of the metal particles is 30% or less, thermal conductivity is low and sufficient heat resistance cannot be obtained. Also, wear resistance is insufficient. If the metal particles are 80% or more, since elastic deformation cannot be performed, a sufficient friction coefficient cannot be obtained in a wide speed range.

When the content of the resin particles is 10% or less, elastic deformation cannot be performed, and a sufficient friction coefficient cannot be obtained in a wide speed range. When the content of the resin particles is 60% or more, thermal conductivity is low, and sufficient heat resistance cannot be obtained. Also, wear resistance is insufficient.

If the number of pores is less than 10% by volume, the removal of the oil film is insufficient, and a high friction coefficient cannot be obtained particularly in a high sliding speed range. On the other hand, if it is more than 40% by volume, the strength is reduced.

The technical measures taken in claim 2 of the present invention are as follows.

As a heat source means for melting or semi-melting the metal particles or resin particles, there is a friction material formed by thermal spraying.

With this configuration, a friction material composed of many pores of material particles having significantly different characteristics such as a melting point sprays the particles in a molten or semi-molten state, and the same type particles are partially fused with each other. Mostly, a thermal spraying method is used in which a mechanical fit and an atomic force are used to fix the structure. This thermal spraying method includes plasma spraying, flame spraying, and high-pressure flame spraying: HVOF (High Velocity Oxyg).
en fuel) is used. This makes it possible to obtain a friction material in which dissimilar particles such as a metal and a resin are firmly fixed together and laminated. Further, since the laminate is formed by spraying the particles, a laminate in which pores formed between the metal particles, the resin particles, and the particles are uniformly dispersed can be obtained.

Further, technical measures taken in claim 2 of the present invention are as follows.

In the friction material, the metal particles have a particle size of 2 to 200 μm, and the resin particles have a particle size of 30 to 300 μm.

The metal particles have a particle size of 2 to 200 μm, and the resin particles have a particle size of 30 to 300 μm, so that the particles in this range can be uniformly dispersed and the characteristics as a friction material are stabilized. If it is out of this range, it cannot be dispersed uniformly, and stable characteristics cannot be obtained.

The metal particles include high-strength brass,
Brass, copper, steel, alloy steel, tin bronze, aluminum bronze, aluminum alloy, titanium, nickel, titanium alloy, nickel alloy and the like are used. As the resin particles, polybutylene terephthalate, nylon, polyketone, polyacetal, polyphenylene sulphite, polybutylene terephthalate, polyethylene terephthalate, polyetherimide, polyethersulfone, polycarbonate, polyimide, phenol and the like are used. Further, a mixture thereof may be used.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings.

EXAMPLE 30% by volume of powdery metal particles of 40 to 106 μm made of high-strength brass (60% of copper, 20% of zinc, the remaining additive), and 30 to 30% of resin particles of polybutylene terephthalate
0 μm was mixed with 20% by volume.

As shown in FIG. 1, the mixed metal particles M and resin particles P are supplied to a supply device (not shown), and the mixed powder is applied to the end face of a cylinder 2 having an outer diameter of 25.6 mm and an inner diameter of 20 mm. Thermal spraying was performed by the thermal spray gun 1 of the thermal spraying apparatus. The plasma spraying conditions at this time were as follows: argon as the working gas and an output of 20 KW. By this plasma spraying, a friction material having a porous body composed of a composite laminate layer of 53% by volume of metal, 36% by volume of resin, and 11% by volume of pores was formed.

The friction material was observed with an electron microscope (× about 20).
0), it was found that a bonding portion in which the metal particles M and the metal particles P were bonded by fusion was formed as shown in FIG. In addition, it was found that, apart from the joint by fusion, a joint by mechanical fitting and atomic force was formed. This composite laminate was polished to a thickness of 0.5 mm and a test piece A
It was created.

Here, high-strength brass is used as the metal particles. This material has a high coefficient of friction, a high abrasion resistance, a low aggressiveness with respect to a mating member, and a good seizure resistance. Therefore, this material was used.

Although polybutylene terephthalate is used as the resin particles, this material has good heat resistance.
This material was used because it has good wear resistance.

Comparative Example Natural pulp fibers such as cotton and hemp described in the prior art, fillers such as diatomaceous earth and silica, and friction modifiers such as graphite and resin particles are blended, and papermaking chemicals are added to wet papermaking. A wet friction material was used in which the special paper was impregnated with a thermosetting resin such as phenol and dried and cured. This paper friction material was cut into an outer shape of 25.6 mm and an inner diameter of 20 mm, and a test piece B was attached to a cylindrical end face having the same shape as the cylinder used in the examples.

Evaluation conditions The test piece A and the test piece B were prepared by using a steel cylindrical end face having an outer diameter of 25.6 mm and an inner diameter of 20 mm and a test machine shown in FIG.
After 0 minute, the peripheral speed was maintained at 0.5 m / sec for 10 seconds to investigate the change in the coefficient of friction.
/ Sec and evaluated. The surface pressure is 784 MpA
a, Evaluation time was 180 minutes. The structure of the tester is as follows: a screw for pressurizing 11, a pressure detector 12 (pressurizing load cell), an upper spring seat 13, a pressurizing spring for 500kg 14, a pressurizing spring 15 for 10kg / 100kg, and a lower spring seat. 16, friction force detector 17,
Torque arm 18, torque detection guide 19, fixed crosshead 20, torque detection shaft 21, needle bearing 2
2. Consists of a thrust bearing 23, a torque shaft 24, a fixed feed 25, a drive shaft 27, a rotating material 26, and a drive shaft 27.

Evaluation Results FIG. 4 is a graph showing the change over time in the friction coefficient showing the relationship between the friction coefficient and the elapsed time. From this graph, the friction coefficient of the comparative example decreases with the lapse of time, while the friction coefficient of the example hardly decreases, indicating a stable result as a friction material. FIG. 5 is a graph showing the relationship between the friction coefficient and the peripheral speed and the change in the friction coefficient depending on the peripheral speed. From this graph, it can be seen that the friction coefficient is low even when the peripheral speed changes in the comparative example, whereas the friction coefficient is high even when the peripheral speed changes in the example. FIG. 6 is a graph in which the wear amount of the example and the comparative example are measured. It can be seen that the wear amount is smaller in the example than in the comparative example.

As described above, the present invention is a friction material having a high coefficient of friction and a small amount of wear, and is suitable as a friction material such as a clutch for transmitting drive from a motor to a transmission or a brake for stopping drive. .

As described above, metal particles and resin particles may be mixed and sprayed in advance as shown in FIG.
As shown in FIG. 7, a plurality of thermal spray guns may be used to control the amount of heat input for each material of metal particles and resin particles, and to melt and spray both materials. This thermal spraying may be plasma spraying, or flame spraying or the like.

[0030]

The present invention has the following effects.

That is, 30 to 80% by volume of metal particles and 10 to 60% by volume of resin particles are blended, and both of the particles are melted or semi-molten by a heat source.
Since the friction material is characterized in that pores of 10 to 40% by volume are formed by chemically and mechanically bonding the resin particles to each other or the metal particles and the resin particles, the base material is made of metal. By doing so, there is no thermal deterioration and heat dissipation can be improved, so that excellent heat resistance can be obtained. Further, by bonding the particles together, pores can be formed between the particles, and by further mixing the resin particles, an elastic body of the friction material itself can be achieved. As a result, the oil film on the sliding surface between the friction material and the counterpart can be quickly removed, and the contact area of the sliding surface can be increased and uniform contact can be obtained by elastic deformation. Can be stably maintained in the area.

Further, since the friction material is formed by thermal spraying as a heat source means for melting or semi-melting the metal particles or the resin particles, the friction material having many pores of material particles having significantly different characteristics such as melting point can be obtained. A method of spraying particles in a molten or semi-molten state, and with the same kind of particles accompanied by partial fusion, most of them are mechanically fitted and fixed by atomic force. Thus, it is possible to obtain a laminated friction material in which dissimilar material particles are firmly fixed to each other. Further, since the laminate is formed by spraying the particles, a laminate in which pores formed between the metal particles, the resin particles, and the particles are uniformly dispersed can be obtained.

The metal particles have a particle size of 2 to 200 μm.
m, and the particle size of the resin particles is 30 to 300 μm, so that the particles in this range can be uniformly dispersed, and the characteristics as the friction material are stabilized.

As described above, the present invention is a friction material suitable as a friction material such as a clutch for transmitting drive from a prime mover to a transmission or a brake for stopping drive.

[Brief description of the drawings]

FIG. 1 is a state diagram in which metal particles and resin particles are mixed in advance and sprayed by plasma spraying.

FIG. 2 is a diagram showing a state in which metal particles and resin particles are put in separate plasma guns and subjected to plasma spraying.

FIG. 3 is a schematic diagram of a testing machine.

FIG. 4 is a graph showing a change in friction coefficient over time, showing a relationship between elapsed time and a friction coefficient.

FIG. 5 is a graph showing a relationship between a peripheral speed and a friction coefficient and showing a change in a friction coefficient with the peripheral speed.

FIG. 6 is a graph showing the amount of wear in Examples and Comparative Examples.

FIG. 7 is a diagram showing a state where metal particles and resin particles are plasma-sprayed using a plurality of plasma spray guns.

[Explanation of symbols]

 1 ... Thermal spray gun M ... Metal particles P ... Resin particles H ... Pores

Claims (3)

[Claims] (1) 30 to 80% by volume of metal particles and resin particles 10
６０60% by volume, and the two particles are melted or semi-molten by a heat source to chemically and mechanically bond the metal particles, the resin particles, or the metal particles and the resin particles. And 10 to 40% by volume of pores. 2. A friction material according to claim 1, wherein said means is a thermal source for melting or semi-melting said metal particles or resin particles. 3. The friction material according to claim 1, wherein the metal particles have a particle size of 2 to 200 μm, and the resin particles have a particle size of 30 to 300 μm.