JPH064959B2 - Wet friction material manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a friction material for a clutch, particularly a wet friction material suitable for use in an oil liquid.

[Prior Art] Conventional automobiles, construction machinery, agricultural machinery, motor boats, etc. transmit a drive from a prime mover to a transmission at any time. A function of cutting off power is required when switching the transmission gears of the transmission. A friction clutch is widely used as a clutch that fulfills such a function. The friction clutch includes a dry clutch used in a dry state and a wet clutch used in oil liquid.

The friction plate of the wet clutch has a structure in which a friction material called paper facing is bonded to both sides of a cored bar. The friction material was thermoformed by impregnating thermosetting resin such as phenolic resin or melamine resin into a base material containing cellulose, inorganic filler such as graphite, asbestos and ceramics, or organic filler such as cashew dust. It is a thing. Since such a material has a high friction coefficient, is highly elastic, and has a high oil absorption rate because it is porous, it is currently used as the most excellent wet friction material.

Friction heat is generated in the friction clutch, so that heat must be efficiently released from the friction portion in order to stably maintain the function. In the wet clutch, oil plays an important role as a heat transfer medium. The heat generated on the friction surface is diffused and released throughout the system by using oil as a medium. Therefore, if the amount of oil held in the friction material itself and the amount of oil flowing in and out are small, heat is not released and the friction material is overheated, causing thermal deterioration of the friction material and oxidative decomposition of the oil, resulting in deterioration of the friction material function. In order to prevent such a situation, a groove through which oil can circulate and flow is provided on the surface of the friction material. An example of such a groove is NSK Bearing Journal magazine (publisher NSK Warner Co., Ltd.) N
o. 638 (issued in 1976), pages 56-57. The groove is usually formed by pressure molding or cutting.

Further, an improved method has been proposed for the shape of the groove and the like.
Japanese Unexamined Patent Publication No. 56-94030 discloses that two types of radial groove edges, a right-angled one and a curved one, are provided to provide a lubricating wedge effect. Also, JP-A-59-54825
The publication discloses that a separator blade facing the disc plate is provided with a through hole in the radial direction or a groove through which the lubricating oil for the cooling is always passed through even when the engaging operation is performed. Further, Japanese Patent Application Laid-Open No. 61-149630 discloses a wet friction material which has not a groove but a base material having different porosity and a flat friction surface.

[Problems to be Solved by the Invention] In the case of a groove formed by conventional molding, the paper density increases in the order of the portion other than the groove, the peripheral portion of the groove, and the groove portion. When they are joined together, the hardnesses of them differ from each other, resulting in uneven contact, causing stick-slip and vibration. Further, in the case of a carved groove, the fiber at the end of the carved groove is cut to have an edge shape, and when it is joined to the metal of the mating material, the contact becomes uneven, which causes vibration. Further, in the case of no groove, stick-slip is less likely to occur, but there is a drawback that the durability is lower than that of a grooved product.

In view of the above, it is an object of the present invention to provide a method for producing a friction material in which stick-slip does not occur by making the density of the paper made into paper uniform including the groove portion and making the fibers in the groove portion continuous without breaking. .

[Means for Solving Problems] The method for producing a wet friction material of the present invention uses a paper net having a paper making surface that is substantially symmetrical to the sliding surface having a predetermined groove of the wet friction material to be produced. A papermaking step of producing a papermaking body having substantially the same sliding surface having the predetermined groove by papermaking a mixture containing at least a base fiber and a filler, and the obtained papermaking body having a sliding surface having the predetermined groove. The present invention is characterized by comprising a mold forming step of using a mold having a mold surface symmetrical to the moving surface and matching the concave and convex portions of the mold surface with the concave and convex portions of the papermaking body.

It is preferable that the predetermined groove and the sliding surface are connected by a curved surface. In the mold forming step, it is desirable that a papermaking plate is laminated on both sides of a disk-shaped cored bar having a central hole, and that the mold is formed by a mold having mold surfaces facing each other.

The base fiber is mainly cellulose fiber, other organic,
Inorganic fibers can also be added. As the filler, an inorganic filler and an organic filler can be used alone or in combination. The inorganic filler is used for the purpose of improving friction performance and heat resistance, and barium sulfate, kaolin, clay, calcium carbonate, silicic acid, alumina, diatomaceous earth, asbestos, graphite and ceramics are used alone or in combination. . As the organic filler, cashew dust or the like is used, and these are uniformly blended in the papermaking body by a usual papermaking method.

The papermaking material thus obtained is impregnated with a phenolic resin or a melamine resin, and heat-molded using a molding die having a sliding surface having a predetermined groove and a mold surface symmetrical with the mold.

By this heat processing and molding, it is possible to obtain a friction material which is uniform and continuous without the fibers being broken in the groove.

[Examples] The present invention will be described below with reference to Examples.

FIG. 1 shows a partial cross-sectional view of an end portion of a circle of a paper making net 1 used in the present invention. This papermaking net 1 has a papermaking surface which is substantially symmetrical to the sliding surface of the friction material having a predetermined groove. That is, the convex portion 2 is formed at a predetermined location.

In the papermaking process, papermaking can be carried out by an ordinary papermaking apparatus according to a conventional method except that the above-mentioned papermaking net 1 is used.
A fiber having the composition shown in Table 1 and a filler are mixed to form a dispersion liquid, and a papermaking body 3 is formed on the papermaking net 1. Fig. 2 shows papermaking net 1
The partial cross section figure of the papermaking body 3 formed above is shown. FIG. 3 shows a partial cross-sectional view of the formed paper body 3. This paper body has grooves 4 which are substantially the same as the sliding surface. Note that this shape needs to take into account shrinkage during molding. Fourth
The figure is a partial cross-sectional schematic view showing a mold forming step. The papermaking body 3 obtained as described above is formed by using molding dies 6 (upper dies) and 7 (lower dies) having a mold surface symmetrical to the sliding surface having a predetermined groove and the unevenness of the papermaking body 3 Match the parts and mold. At this time, the grooves 4 of the papermaking body 3 are formed on both sides of the disk-shaped cored bar 5 having a central hole.
Is laminated with the surface having the above as the molding die surface side. The mold surfaces of the molding dies 6 and 7 are provided with convex portions 8 so that the grooves 4 of the papermaking body 3 and the convex portions of the mold surfaces are aligned as shown in FIG. A predetermined amount of papermaking body 3 sandwiching the core metal 5 (first
(Shown in the table) is impregnated with the phenol resin and is heated under pressure by the molding dies 6 and 7 to be molded. A partial cross section of the obtained friction material is shown in FIG. This friction material is the friction member 9
Are sandwiched by the core metal 5, and the same groove as the sliding surface is formed on the surface. It should be noted that in the composition of the papermaking body, B is used for A
Indicates that the number of fibers is reduced and the amount of the organic filler is increased, and C indicates that the amount of the inorganic filler is reduced to that of B and the inorganic fiber is added accordingly.

FIG. 6 shows a plan view of the friction material 11. This friction material is formed by sandwiching a friction material 9 on both sides of a core metal 5, and forming grooves 10 on the surface of the friction material so as to face each other. Here the mold 6,
The convex portions 8 of No. 7 and the grooves 10 of the friction material 9 had substantially the same pitch height.

The molding conditions are a surface pressure of 1250 kg / cm ² and a thermoforming temperature of 20.
The molding time is 2 minutes at 0 ° C. The dimensions of the friction material are a lining thickness of 0.52 mm, a lining outer diameter of 126 mm, a lining inner diameter of 105 mm, a core plate thickness of 0.8 mm, and a groove shape of double parallel 9 grooves.

As a comparative material, a non-grooved product (Comparative Example 1), a double parallel 9-groove product manufactured by cutting (Comparative Example 2), and a double parallel 9-groove product manufactured by pressing (Comparative Example 3) were prepared with the same composition as that of the example. Then, the following test was conducted in the same manner as in the example.

The tester was a SAE # 2 type tester, the surface pressure was 30 kg / cm ² , the rotation speed was 5 rpm, and the oil used was Dexron II manufactured by Idemitsu Petroleum Co., Ltd. The torque fluctuation was measured at an oil temperature of 20 ° C.
The results are shown in Fig. 7. The fluctuation range (runout width) of the torque was small for the non-grooved products of the examples and comparative examples, but the torque fluctuations were high even if the composition was changed in the cutting and pressing products. Therefore, the groove formed by the manufacturing method of the present invention is an excellent wet friction material having a small torque fluctuation range.

Endurance cycle test: rotation speed 5000 rpm, surface pressure 10 kg
/ Cm ² , oil temperature 80 ° C, inertia 2.0 kgcmS ² , and the number of friction plates was 5, and the test was performed under the same conditions as the above torque fluctuation test. The results are shown in FIG. When the groove is formed by the friction material having the groove formed by the manufacturing method of the present invention and the groove is formed by cutting, the durability is excellent, but the durability without groove is remarkably poor. Therefore, the present invention is a manufacturing method for providing a friction material that reduces torque fluctuations, suppresses the occurrence of stick slips, and has excellent durability. The groove forming method of the present invention can be applied to any shape other than the above.

[Effects of the Invention] The method for producing a wet friction material of the present invention comprises a papermaking step of making a papermaking body with a papermaking net having a papermaking surface that is approximately type-symmetric with a sliding surface having a predetermined groove, and sliding the papermaking body. The wet friction material obtained by performing the molding process that uses a mold having a mold surface that is symmetrical to the surface has a uniform density, and the fibers in the groove generated by cutting etc. are cut and discontinuous. Since it does not occur, the torque fluctuation is reduced and the occurrence of stick slip is suppressed,
In addition, it is a manufacturing method by which a friction material having excellent durability can be obtained.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing a paper making net of the present invention.
From the figure, FIG. 5 is a partial cross-sectional view showing the state of the friction material formed in the manufacturing process. FIG. 2 shows the paper making, FIG. 3 shows the paper making body,
FIG. 4 is a schematic diagram at the time of pressure molding, FIG. 5 shows a molded body, FIG. 6 is a plan view of a friction material, FIG. 7 is a graph showing torque fluctuation results, and FIG. Is a graph showing the results of the durability test. DESCRIPTION OF SYMBOLS 1 ... Paper net 2 ... Groove convex part of paper net 3 ... Paper making body 4, 10 ... Groove 5 ... Core metal 6 ... Mold upper die 7 ... Mold lower die 8 ... Mold groove convex portion 9 ... Friction material

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Claims (3)

[Claims] 1. A papermaking net having a papermaking surface which is substantially symmetrical to a sliding surface having a predetermined groove of a wet friction material to be produced,
A papermaking process for producing a papermaking body having substantially the same sliding surface having the predetermined groove by papermaking a mixture containing at least a base fiber and a filler, and sliding the obtained papermaking body having the predetermined groove. A wet friction material characterized by using a forming die having a die surface symmetrical to the surface, and having a die forming step of forming an uneven portion of the die surface and an uneven portion of the papermaking body in conformity with each other. Production method. 2. The method for producing a wet friction material according to claim 1, wherein the predetermined groove and the sliding surface are connected by a curved surface. 3. The mold forming step according to claim 1, wherein the papermaking plates are laminated on both sides of a disk-shaped cored bar having a central hole, and mold forming is carried out by a mold having mold surfaces facing each other. Of the wet friction material of.