JPH08326793A - Non-asbestos series disk pad - Google Patents

Abstract

PURPOSE: To provide a non-asbestos series disk pad reducing generation of crack in the use at high temperature without changing frictional characteristic. CONSTITUTION: In a non-asbestos series disk pad, an insulator of bending strength over 5MPa at under 200 deg.C, maximum strain over 10×10<-3> mm/mm at under 200 deg.C, and thermal conductivity under 2W/mK, is interposed between a back metal and a friction member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-asbestos disc pad suitable for a braking member for automobiles and the like.

[0002]

2. Description of the Related Art As a friction member for a brake pad of a conventional disc brake, Japanese Patent Publication No. 56-25448 has been proposed.
Asbestos fibers such as those disclosed in Japanese Patent Publication No. 56-48530 have been used, but recently, asbestos fibers are harmful, and as a substitute fiber for asbestos fibers, Japanese Patent Publication No. 59-4.
As shown in Japanese Patent Publication No. 462, etc., materials mainly composed of metal fibers such as steel fibers have been used.

However, since metal fibers have a higher thermal conductivity than conventional asbestos fibers, the frictional heat generated during braking is more likely to be transmitted to the brake oil side, and the so-called vapor lock phenomenon easily occurs. For this reason, in recent years, there has been a gap between the friction member forming the disc pad and the back metal.
As disclosed in JP-A-3-37535, JP-B-63-50503, etc., it is proposed to sandwich a heat insulating material (hereinafter referred to as an insulator) having a thermal conductivity lower than that of the friction member.

The main purpose of the insulator is to reduce the heat conductivity so that frictional heat is not transmitted to the brake oil. However, as the wear of the disk pad progresses, the insulator part may be exposed on the surface. To be Therefore, it must have some degree of frictional characteristics (friction coefficient, wear resistance, etc.).

Therefore, as the insulator, it is required to use a material similar to the material of the friction member and having a further heat insulating effect. However, disc pads are not only characterized by friction coefficient and wear resistance, but recently, as the performance of vehicles has increased, the load on the disc pads has increased,
For example, it may be used at a temperature higher than the heat resistance limit of the friction member, causing a problem that cracks occur on the side surface of the disk pad.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a non-asbestos type disk pad in which the occurrence of cracks during high temperature use is reduced without changing the friction characteristics.

[0007]

DISCLOSURE OF THE INVENTION As a result of various studies on the method for improving the squeal, the present inventors have focused their attention on an insulator material which has mainly been used only as a heat insulating material, and have found that the bending strength of the insulator material is large. The inventors have found that it is possible to reduce the occurrence of cracks by adjusting the maximum strain and the thermal conductivity, and have completed the present invention.

According to the present invention, the bending strength between the backing and the friction member is 5 MPa or more at 200 ° C. or less, the maximum strain is 10 × 10 ⁻³ mm / mm or more at 200 ° C. or less, and the thermal conductivity is 2 W /. The present invention relates to a non-asbestos disk pad having an insulator of mk or less interposed.

In the present invention, as the friction member, metal fibers such as steel fibers, copper fibers and brass fibers, organic fibers such as aramid fibers and phenol fibers, fibrous substances composed of ceramic fibers, phenol resin, NBR rubber, SBR.
Binders such as rubber and natural rubber, inorganic fillers such as barium sulfate, calcium carbonate and magnesium carbonate, organic fillers such as hardened cashew, and lubricants such as graphite and molybdenum disulfide are used.

Further, as an insulator, since the disk pad is worn away and the friction member portion disappears, it is necessary to prevent the friction coefficient and the wear characteristics from largely changing even if only the insulator portion is present. Therefore, it is similar to the friction member. The material is used, and the material with high thermal conductivity is reduced or the material with low thermal conductivity is increased to adjust the elastic modulus to 8 GPa or less at room temperature and 4.2 GPa or less at 120 ° C. Used.

The insulator is 8 GPa or less at room temperature, preferably 7 GPa or less, and 4.2 GPa or less at 120 ° C.
It is preferable to use a material having an elastic modulus of 4.0 GPa or less from the viewpoint of preventing squeaking when the brake is depressed.

The insulator has a bending strength of 200.
5 MPa or more at ℃ or less, preferably 13.2 MPa or more, maximum strain is 10 × 10 ^-3 mm / mm or more at 200 ° C or less, preferably 19.9 × 10 ^-3 mm / mm or more and thermal conductivity is 2 W / mk or less, preferably 1.25 W / mk or less, and bending strength of 2
If the temperature is less than 5 MPa below 00 ° C, the friction member surface will rapidly rise in temperature during braking and the torque generated will be
The insulator cannot withstand and cracks occur. If the maximum strain is less than 10 × 10 ^-3 mm / mm at 200 ° C or less, the insulator cannot follow the thermal expansion that occurs during the rapid temperature change of the friction member and the back metal part during braking, and the friction member and the insulator material Cracks are likely to occur at the interface. Further, when the thermal conductivity exceeds 2 W / mk, the heat generated on the surface of the friction member is conducted inside the disc pad to raise the temperature of the brake oil, and the vapor lock phenomenon easily occurs.

[0013]

[Function] Cracks under a high load of a vehicle can withstand the torque stress generated during braking and the stress generated by the difference in thermal expansion between the friction member and the insulator due to heat by increasing the bending strength and the maximum strain. It is considered possible.

[0014]

EXAMPLES Examples of the present invention will be described below. 20% by volume of steel fiber (made by Rose) with a length of 2 mm as a friction member, 5% by volume of aromatic aramid fiber (Kevlar fiber, a product name by DuPont), phenolic resin (in-house, not for sale)
25% by volume, NBR powder (NIPOL1411, product name of Nippon Zeon Co., Ltd.) 5% by volume, graphite (KS-15, product name of Lonza Co., Ltd.) 30% by volume and barium sulfate (barite powder, manufactured by Guangdong China Gold Co., Ltd.) 15% by volume was thoroughly mixed with a Henschel mixer to obtain a molding powder for friction members.

On the other hand, as an insulator, the composition shown in Table 1 was weighed to a blending ratio of A, B, C, D, E, F, G, H, I and J, and thoroughly mixed with the same Henschel mixer as above. To obtain a molding powder for an insulator. The same raw materials as above were used except for rock wool (RF51Z5, trade name manufactured by Lapinus).

After that, a back metal was placed in the mold, and the upper surface thereof was filled with insulator forming powder and friction member forming powder in this order, and 1.47 × 10 ⁷ Pa (150 kgf / cm ² ) and 170
By heating under pressure at 10 ° C. for 10 minutes, a molded body having an insulator interposed between the backing metal and the friction member was obtained. Then, the surface was finished to obtain a non-asbestos disk pad.

The non-asbestos-based disc pad A obtained next,
40 mm x 7 from B, C, D, E, F, G, H, I and J
The insulator was cut out to a size of mm × 2.5 mm, the viscoelasticity from room temperature to 360 ° C. was measured, and the elastic modulus from room temperature to 120 ° C. was obtained. Further, the bending strength, the maximum strain and the thermal conductivity of the cut out insulator were measured, and the presence or absence of cracking and the vapor lock were investigated. The results are shown together in Table 1.

Under the above test conditions, the bending strength and the maximum strain were 2 in accordance with the standard specified in JIS D4311.
Measured at a temperature of 00 ° C, the thermal conductivity is measured by Kyoto Electronics Manufacturing Co., Ltd.
Manufactured using Kemtherm QTM-D3, and the presence or absence of cracks is confirmed by performing a fade test based on JISO C406-82 category P1 for 2 cycles and confirming the presence or absence of cracks. , Sensory evaluation was performed by pedal stroke.

[0019]

[Table 1]

As shown in Table 1, it was confirmed that the non-asbestos disk pad according to the present invention did not cause cracks and had no vapor lock problem.

[0021]

INDUSTRIAL APPLICABILITY The non-asbestos disk pad according to the present invention is an industrially extremely suitable non-asbestos disk pad that can reduce the occurrence of cracks at high temperatures without changing friction characteristics.

Claims (1)

[Claims] 1. A bending strength of 2 between the back metal and the friction member.
5 MPa or more at 00 ° C or less, 10 at maximum strain of 200 ° C or less
A non-asbestos disc pad with an insulator having a thermal conductivity of 2 × 10 ⁻³ mm / mm or more and a thermal conductivity of 2 W / mk or less.