JPH06173983A - Manufacture of wet type frictional member - Google Patents

Abstract

PURPOSE:To provide a frictional member having little fluctuation in friction coefficient by forming a paper base material of a mixture material of base material fiber, an inorganic filler, and a friction adjusting material, impregnating a bonding resin in the paper base material, followed by heating and molding, and bringing hot plates each having of a temperature higher than that during heating and molding into contact with the friction surface, followed by a heat treatment. CONSTITUTION:35wt.% of cellulosic fiber, 15wt.% of synthetic fiber, + or -20wt.% of diatom as an inorganic filler, and 10wt.% of cashew nut dust as a friction adjusting material are mixed, to be dispersed in water, followed by papermaking, thus forming a paper base material. After the paper base material is dried, a phenol resin is impregnated in the content of 20wt.%. The mixture is hardened in a molding die, which is heated at 200 deg.C, after being dried by wind, thereby obtaining a frictional member 1. The frictional members 1 are stuck to both surfaces of a core metal 2 through an adhesive, thus obtaining a frictional plate, which is mounted on a lower hot plate 5 together with a spacer 4. The frictional plate is held between an upper hot plate 3 and the lower hot plate 5, temperatures of which are higher by 50-150 deg.C than that during heating, followed by a heat treatment for a predetermined period. Consequently, it is possible to smoothen the surface of the frictional member 1, to promote hardening of the bonded resin, and to restrain fluctuation in friction coefficient during use.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wet friction material used for clutch facing of an automatic transmission of an automobile.

[0002]

2. Description of the Related Art The clutch facing of an automatic transmission is
It is called a wet friction material because it is used in oil. This wet friction material includes fiber base materials selected from various organic and inorganic fibers such as pulp, aromatic polyamide fibers and glass fibers, calcium carbonate, silica, barium sulfate,
It is made of a mixed material in which an inorganic filler such as diatomaceous earth is mixed with a friction modifier such as cashew dust or graphite.

To produce a wet friction material from this mixed material, for example, as disclosed in Japanese Unexamined Patent Publication No. 62-266238, first, the mixed material is dispersed in water, and then a round-net papermaking machine or a Fourdrinier machine is used. A paper-making base material is obtained by making paper with a type paper making machine or the like. Phenolic resin, melamine resin,
A friction material having a predetermined thickness is manufactured by impregnating a thermosetting resin such as an epoxy resin and compressing while heating.

[0004]

However, if the conventional wet friction material produced as described above is used as it is,
Thermal deterioration due to frictional heat during use and smoothing due to fatigue and wear progress at the same time, and a steady friction surface is gradually formed. Therefore, although the friction coefficient is low at the beginning of use, the friction coefficient gradually increases during use, and a stable value occurs after a while. Therefore, there is a problem that a gear shift is delayed due to insufficient friction torque at the initial stage of use, and a gear shift feeling varies with use.

In order to deal with this problem, conventionally, a wet friction material surface rubbing process is performed in an assembly line to provide a so-called "hit".
However, the laminating step has a problem in terms of man-hours such as a long tact time, and also has a problem that a defective product such as a burn is generated at the time of laminating, resulting in a large loss, resulting in poor production efficiency.

The present invention has been made in view of such circumstances, and an object thereof is to easily form a wet friction material having no fluctuation in friction coefficient.

[0007]

In the method for producing a wet friction material of the present invention which solves the above problems, a paper material base material is formed by papermaking from a mixed material containing a base fiber, an inorganic filler and a friction modifier. And a step of impregnating a paper base material with a binder resin and heat-molding to form a wet friction material, and a friction plate of the wet friction material is contacted with a hot plate having a temperature 50 to 150 ° C. higher than the heating temperature at the time of heat molding. And a step of heat treatment are sequentially performed.

In the heat treatment step, it is desirable to control the distance between the hot plate and the wet friction plate to be 0 to 0.2 mm. When the distance is 0 or less, that is, when the wet friction material is compressed, the number of pores inside the friction material is reduced, and in some cases, some of the pores adhere to the hot plate and peel off. On the other hand, if the distance is larger than 0.2 mm, the adhesion with the friction material will be impaired and uneven treatment will occur.

[0009]

The method for producing a wet friction material of the present invention is characterized in that a heat plate is brought into contact with a wet friction material obtained in the same manner as in the prior art to perform heat treatment. As a result, the irregularities on the surface of the friction material are smoothed. Further, the hardening reaction of the binder resin in the friction material is promoted, and the shape of the friction material is fixed while the surface is smoothed. Therefore, a friction coefficient equivalent to the used constant friction surface is obtained from the beginning of use, and fluctuations in the friction coefficient during use are suppressed.

When the temperature of the hot plate during the heat treatment is lower than the heating temperature during the heat forming + 50 ° C., the fixing of the smooth shape due to the curing of the binding resin becomes insufficient and the shape is restored after the heat treatment, so that a smooth surface is obtained. I can't. Further, when the heat treatment is performed at a temperature higher than the heating temperature + 150 ° C. at the time of heat molding, the surface of the friction material that comes into contact with the hot plate is carbonized, and the surface becomes rough and the friction characteristics deteriorate.

[0011]

EXAMPLES The present invention will be specifically described below with reference to examples. (Example 1) 35 parts by weight of cellulose fiber, 15 parts by weight of synthetic fiber (aromatic polyamide fiber), 20 parts by weight of diatomaceous earth as an inorganic filler, and 10 parts by weight of cashew dust as a friction modifier are mixed into water. The material was dispersed and paper-made by a round-net paper-making machine to form a paper base material.

After the paper base material is dried, it is impregnated with a phenol resin to a content of 20% by weight, and air-dried to 20%.
It was placed in a mold which was heated and maintained at 0 ° C., and cured by heating. After that, the center was punched out to form a ring-shaped wet friction material. The obtained friction material 1 was adhered to both surfaces of the cored bar 2 with an adhesive to form a friction plate, which was placed on the lower heating plate 3 together with the spacer 4 as shown in FIG. The spacer 4 is arranged in the center hole of the friction material 1. Here, the thickness of the spacer 4 is 2
The total thickness of the friction material 1 and the core metal 2 is +0.1 mm. Then, it was sandwiched between the upper heating plate 5 and the lower heating plate 3 and held for a predetermined time to perform heat treatment.

The temperature of each of the lower heating plate 3 and the upper heating plate 5 is 2
Heat treatment was performed at 50 ° C. for 5 minutes. The three friction plates obtained were mounted on a SAE # 2 tester, and the joint rotation speed was 360.
The change in friction coefficient (μ _d ) with respect to the number of joints was measured under the conditions of 0 rpm, inertia 3.5 kg · cm · sec ² , pressing load 400 kg, oil temperature 100 ° C. and jointing cycle 30 seconds. The results are shown in Figure 2.

Further, the surface roughness of the friction surface of the friction material 1 is cut.
Relative load length t at level p = 5 μm _pExpressed as a percentage and the result
It shows in Table 1. The relative load length is also called the contact ratio.
The higher the value, the higher the smoothness. (Example 2) The temperature of the lower heating plate 3 and the upper heating plate 5 during heat treatment
Except that the temperature was set to 300 ° C and the heat treatment time was set to 1 minute.
This is the same as in the first embodiment. Friction measured as in Example 1
Fig. 2 shows the change in the coefficient and Table 1 shows the relative load length.
You (Example 3) The temperature of the lower heating plate 3 and the upper heating plate 5 during heat treatment
Except that the temperature was 350 ° C. and the heat treatment time was 30 seconds.
This is the same as in the first embodiment. Abrasion measured as in Example 1
Fig. 2 shows the change of friction coefficient and Table 1 shows the relative load length.
Show. (Comparative Example 1) Without heat treatment, it is heat-formed and stamped into a predetermined shape.
Except that the friction material 1 that was punched out was used as is
Similar to Example 1. Friction coefficient measured as in Example 1
Figure 2 shows the change in the number and Table 1 shows the relative load length.
You (Comparative Example 2) The temperatures of the lower heating plate 3 and the upper heating plate 5 during the heat treatment are
Except that the temperature was 220 ° C. and the heat treatment time was 10 minutes.
This is the same as in the first embodiment. Abrasion measured as in Example 1
Fig. 2 shows the change of friction coefficient and Table 1 shows the relative load length.
Show. (Comparative Example 3) The temperature of the lower heating plate 3 and the upper heating plate 5 during heat treatment
Except that the temperature was 380 ° C. and the heat treatment time was 10 seconds.
This is the same as in the first embodiment. Abrasion measured as in Example 1
Fig. 2 shows the change of friction coefficient and Table 1 shows the relative load length.
Show.

[0015]

[Table 1] (Evaluation) From Table 1, it can be seen that the friction materials obtained in the respective examples have improved surface smoothness as compared with the conventional friction material of Comparative Example 1 in which the heat treatment is not performed. In Comparative Example 2 where the heat treatment temperature is low, high smoothness cannot be obtained even if the heat treatment time is extended, and when the heat treatment temperature is as high as 380 ° C., the smoothness is reduced due to carbonization even in a short time treatment. . Further, it can be seen that the friction material of Example 2 is particularly high, and heat treatment conditions of this degree are optimal.

As shown in FIG. 2, in the examples, the friction coefficient was high and stable from the beginning of use, whereas in the comparative examples 1 and 2, the friction coefficient was low in the initial stage and the number of joints increased. It can be seen that it took time to rise and stabilize. Further, in Comparative Example 3, the friction coefficient was lower than that of the example until the number of joints was 150, and the number of joints was 20.
At 0 times, the friction coefficient suddenly increased. It is speculated that this is because the carbonized layer on the surface was scraped.

That is, it is clear that the results of Table 1 and the results of FIG. 2 have a very high correlation, and that the heat treatment of this example makes it possible to produce a friction material having a high smoothness and a stable friction coefficient from the beginning of use. That is, by the manufacturing method of the present invention, a friction material that exhibits stable friction characteristics from the beginning can be easily prepared.
And it is clear that it can be manufactured stably.

[0018]

According to the method for producing a wet friction material of the present invention, a friction material having a high friction coefficient from the initial stage of use and a stable friction coefficient during use can be easily and reliably produced. be able to. Therefore, if the obtained friction material is used for a clutch facing of an automatic transmission, a stable shift feeling can be obtained from the initial stage of use.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a flow of a heat treatment process in an example of the present invention.

FIG. 2 is a graph showing the relationship between the number of joints and the coefficient of friction in the example of the present invention.

[Explanation of reference symbols] 1: Friction material 2: Core metal 3: Lower heating plate 4: Spacer 5: Upper heating plate

Claims (1)

[Claims] 1. A step of forming a paper base material by papermaking from a mixed material containing a base fiber, an inorganic filler and a friction modifier, and a wet friction by impregnating the paper base material with a binder resin and heat-molding the paper base material. Wet friction, which comprises sequentially performing a step of forming a material and a step of heat treating the friction surface of the wet friction material with a hot plate having a temperature higher by 50 to 150 ° C. than the heating temperature at the time of heat molding. Method of manufacturing wood.