JPH02134426A - Friction material and manufacture thereof - Google Patents

Abstract

PURPOSE:To abate the occurrence of any creakiness by making the extent of hardness in a peripheral part or both sides lower than the central part as much as the specified value, in a friction material of a disk pad, lining or the like consisting of a fiber ingredient other than asbestos, thermosetting resin ingredient and a filler. CONSTITUTION:A direction material 2 consisting of a fiber ingredient other than asbestos, a thermosetting resin ingredient of phenolic resin or the like, and a filler powder ingredient of graphite and barium sulfate or the like is formed no a back plate 1 of a friction pad, thereby securing an automobile disk pad. In this case, temperature in an inner mold of a die coming into contact with peripheral parts 3, 4 is made lower than that of both upper and lower molds and thereby heating pressure molding takes place, while after-core is carried out, and hardness of these peripheral parts 3, 4 is made lower than that of the central part as much as 5-20 on a scale of Rockwell hardness S. Thus, a generating rate of creakiness at time of braking is abatable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a friction material used as brake pads, brake linings, clutch facings, etc. of automobiles, and a method for manufacturing the same.

[Conventional technology]

Conventionally, automobile brake pads, brake linings,
Asbestos is often used as a base material for friction materials used in clutch facings, etc., but as it has been pointed out that asbestos dust is harmful to the human body, its use is being regulated, and asbestos There is a growing demand for friction materials that do not require the use of friction materials.

Therefore, many proposals have been made for friction materials that do not use asbestos, but most of them use glass fiber, metal fiber, or heat-resistant organic fiber as the base material.

[Problem to be solved by the invention]

In general, automotive brakes are equipped with a pair of pads supported by supports on either side or inside of a rotor or drum that rotates with the wheels. During braking, the brakes are pressed against the rotor or drum surface to achieve braking. Vibration caused by friction between the sliding body and the sliding body generates a noise called squeal.

Therefore, there is a problem in that this noise occurs more frequently in non-asbestos friction materials, especially during braking at low speeds.

Conventionally, in order to prevent this noise, composite friction materials have been proposed in which a part of the friction material has a composition with good vibration characteristics, but the noise prevention effect is insufficient or
There were problems such as increased manufacturing costs.

[Means to solve the problem]

The present invention was developed with the aim of solving the above-mentioned problems with conventional non-asbestos friction materials, especially the problem of squeaking, and its composition consists of fiber components other than asbestos, phenolic resin, etc. In friction materials such as disc pads and linings made of a thermosetting resin component and a filler powder component such as graphite or barium sulfate, the hardness of the periphery or both sides is lower than the hardness of the center on the Rockwell hardness S scale. So 5
It is characterized by lowering the temperature by ~20%.

That is, as a result of repeated research aimed at providing stable friction performance to non-asbestos friction materials and reducing the occurrence of squeal during braking, the inventor of the present invention has found The present invention was achieved based on the knowledge that the above object can be achieved by making the hardness of the peripheral part or both sides 5 to 20 lower on the Rockwell hardness S scale than the hardness of the outer part.

In addition, when the above-mentioned friction material materials are uniformly mixed and put into a mold and molded under heat and pressure, the above-mentioned friction material can be used in the middle part of the mold that contacts the area where the hardness of the molded friction material is reduced. Molding is performed while controlling the temperature to be 5 to 20 degrees Celsius lower than the temperature of the upper and lower molds, or the amount of friction material in areas where the hardness of the molded friction material is lower is harder than that in areas with higher hardness. It is manufactured by reducing the amount by the amount corresponding to the difference and preforming it, or by heating and press molding it as it is.

In the present invention, the fiber components used include inorganic or metallic fibers such as glass fibers, ceramic fibers, steel fibers, stainless steel fibers, copper fibers, or metal fibers such as bronze fibers, and staples. Examples include bulb fibers such as fibers, organic fibers such as aramid fibers, polyamide fibers, and polyimide fibers, and sepiolite fibers may be used if necessary.

Examples of the binder include thermosetting resins such as phenol resins, urea resins, melamine resins, and modified resins thereof, and heat-resistant resins such as polyacetals, aromatic polyimide resins, and fluororesins.

Additionally, graphite is used as a friction modifier and filler.

There are lubricating substances such as molybdenum disulfide and cashew dust, barium sulfate, and calcium carbonate.
Materials with relatively high Mohs hardness, such as zircon sand and alumina, are also used as fillers.

(Operation of the invention) In the present invention, since the hardness of the peripheral part of the friction material is lower than the hardness of the central part, the vibration characteristics are improved without changing the composition of the pad or lining material, etc., and during braking, Since excessive contact force is not applied to the periphery where the contact force does not have to be greater than that at the center, the generation of squeal is significantly prevented.

〔Example〕

Next, the structure of the present invention will be explained with reference to the drawings.

In Figures 1 and 2, 1 is the back metal of the friction pad, 2
is a friction material, 3 and 4 indicate low hardness parts of the friction material, Fig. 1 shows a case in which a low hardness part is provided in the entire peripheral area, and Fig. 2 shows a case in which a low hardness part is provided on both sides. shows.

Examples of the method for manufacturing the friction material of the present invention will be described below.

Example 1 Aramid fiber 10% by volume glass fiber
15 Phenol resin 20 Graphite 15 Barium sulfate 20 Other fillers 20 After uniformly mixing tt, the first
In order to form the friction material pad shown in the figure, it is placed in a mold, and the temperature of the middle part of the mold that contacts the peripheral area of the friction material where the hardness is to be lower than the center part is set to 140°C, and the temperature of the upper and lower molds is set to 140°C. Heat and pressure molding was carried out at a temperature of 150° C. and a pressure of 200 kg/ad for 10 minutes, followed by after-curing at 180° C. for 5 hours to obtain a pad of a friction material as an example of the present invention.

This friction material had a squeal generation rate of 0.05%.

Example 2 After uniformly mixing friction material having the same composition as in Example 1, in order to form the friction material pad shown in FIG. 2% less per unit area, 150°C.

Heat and pressure molding was carried out at a pressure of 200 kg/cd for 10 minutes, followed by after-curing at 180° C. for 5 hours to obtain a separate friction pad of the present invention.

This friction material had a squeal generation rate of 0.8%.

Comparative Example After uniformly mixing friction material materials with the same components as in Example 1, the temperature was 150°C and the pressure was 200 g/d for 10 minutes in order to mold the friction pad into a uniform friction pad similar to the conventional friction pad. It was molded under heat and pressure, and then after-cured in the same manner as above to obtain a friction pad.

This friction material had a squeal occurrence rate of 14.2%.

〔Effect of the invention〕

As described above, the friction material of the present invention has an extremely low incidence of squealing during braking compared to a conventional friction pad in which the friction material is uniformly molded over the entire surface.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention. Fig. 1 is a plan view of a friction pad in which a low-hardness part is provided on the entire periphery, and Fig. 2 is a plan view of a friction pad in which a low-hardness part is provided on both sides. It is. 1...Friction pad back metal, 2...Friction material, 3, 4.
...The part of the friction material with low hardness

Claims (1)

[Scope of Claims] 1. Friction materials such as disc pads and linings comprising a fiber component other than asbestos, a thermosetting resin component such as a phenol resin, and a filler powder component such as graphite or barium sulfate, in which the peripheral portion Or, a friction material characterized in that the hardness of both sides is 5 to 20 lower on the Rockwell hardness S scale than the hardness of the center part. 2. The friction material according to claim 1, wherein regions having different hardness can be distinguished into a central portion of the friction material, and a front portion and a rear portion with respect to the sliding direction. 3. When a friction material consisting of a fiber component other than asbestos, a thermosetting resin component such as a phenol resin, and a filler powder component such as graphite or barium sulfate is placed in a mold and heated and press-molded, the The temperature of the middle part of the mold that contacts the area where the hardness of the friction material is lowered is 5 to 2 times higher than the temperature of the upper and lower molds.
A method for manufacturing a friction material, characterized by molding while controlling the temperature to be as low as 0°C. 4. When a friction material consisting of a fiber component other than asbestos, a thermosetting resin component such as a phenol resin, and a filler powder component such as graphite or barium sulfate is placed in a mold and molded under heat and pressure, The amount of friction material in the area where the hardness of the friction material is lowered is smaller than the amount of friction material in the area where the hardness is greater by an amount corresponding to the generation of hardness, and the material is preformed or heated as is. A method for manufacturing a friction material, characterized by pressure molding.