JPH0763228A - Wet type frictional material - Google Patents

Abstract

PURPOSE:To provide a wet type frictional material profitable in a manufacturing cost by reducing the occurrence of stick-slip vibration and resultant abnormal noise at the time of slip operation without applying secondary working and surface treatment. CONSTITUTION:A wet type frictional material 1 is composed of a ringlike base material 2 and a frictional member 3 having a frictional surface 30, jointed to the ringlike base material 2 and also pushedly pressed to the rubbed surface of a relatively rotating partner member, and the frictional member 3 has its frictional surface of a fine recessed and protruded surface having 100-1000mum pitches.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a wet friction material.

[0002]

2. Description of the Related Art Generally, wet friction materials are used as parts for automobile wet multi-disc clutches and viscous couplings. This wet friction material is used by being pressed against the surface to be rubbed of a relatively rotating mating member (metal plate). At this time, stick-slip vibration and abnormal noise may be generated.

The cause of this is that the contact area between the friction surface and the rubbed surface changes in the sliding direction due to variations in the flatness of the friction surface of the wet friction material or the rubbed surface of the mating member. Variations in distribution and coefficient of friction, sliding resistance is small and slippery in low surface pressure areas, sliding resistance is high in areas with high surface pressure, and slippage occurs and discontinuous sliding occurs, resulting in transmission torque fluctuations. Conceivable.

Therefore, in the conventional case, the friction surface of the wet friction material or the surface to be rubbed of the mating material is subjected to secondary processing for improving the flatness thereof, or is precisely finished.
The surface to be rubbed is subjected to surface treatment such as hard chrome plating to minimize the variation in the surface pressure distribution.

[0005]

However, the secondary processing and the surface treatment are disadvantageous in terms of manufacturing cost, and the secondary processing cannot always obtain a sufficient effect due to the limit of accuracy. An object of the present invention is to provide a wet friction material that solves the above conventional problems.

[0006]

The wet friction material of the present invention comprises:
In a wet friction material comprising a ring-shaped base material and a friction member having a friction surface that is joined to the ring-shaped base material and is pressed against the friction surface of a mating member that relatively rotates, the friction member comprises: It is characterized in that the friction surface is a minute uneven surface having a pitch of 100 to 1000 μm.

When the wet friction material of the present invention is used, when it is pressed against the surface to be rubbed of a mating member, a large number of minute projections come into contact with the surface to be rubbed at a pitch of 100 to 1000 μm, so that sliding occurs. It is possible to make the surface pressure distribution uniform in the contact area in the direction. As a result, the contact area does not change significantly in the sliding direction, eliminating the occurrence of discontinuous sliding.
It is possible to reduce the occurrence of stick-slip vibration and abnormal noise.

The reason why the pitch of the minute uneven surface formed on the friction surface of the friction member is 100 to 1000 μm is that when the pitch is in the above range, stick-slip vibration and abnormal noise can be reduced, and the pitch can be reduced. Below 100 μm and above 1000 μm, the occurrence of stick-slip vibration and noise increases. The height distance from the peak of the convex portion of the minute uneven surface to the bottom of the concave portion is 50 to 500 μm.
Is preferred.

The fine uneven surface can be formed by, for example, a linear projection or a linear groove provided on a plane in a concentric circle shape or a spiral shape. Further, the minute uneven surface may be formed by a plurality of linear protrusions or linear grooves provided on the plane so as to intersect with each other. The cross-sectional shape of the minute uneven surface may be a triangle, a quadrangle, or a shape similar to each of the above-mentioned polygons.

[0010]

In the wet friction material of the present invention, the friction surface of the friction member pressed against the friction surface of the mating member that rotates relative to each other is formed with a minute uneven surface having a pitch of 100 to 1000 μm. When the wet friction material is pressed against the surface to be rubbed of the mating member, a large number of minute projections are 100 to 1000 μm.
Since they contact the rubbed surface at m pitches respectively, the surface pressure distribution in the contact area in the sliding direction can be made uniform.

As a result, since the contact area does not change greatly in the sliding direction, the occurrence of discontinuous sliding is eliminated, and stick-slip vibration and abnormal noise can be reduced. Further, when the friction surface of the wet friction material of the present invention is formed as a minute uneven surface having a pitch of 100 to 1000 μm, the ring-shaped base material and the friction member are sandwiched between the lower mold and the upper mold of the heat press molding machine and heated. In the process of manufacturing the wet friction material by joining, it is only necessary to perform the transfer processing by the press transfer surface having the fine uneven surface shape of the pitch formed in advance on the lower mold and the upper mold.

Therefore, unlike the prior art, the friction surface of the wet friction material and the friction surface of the mating member do not require secondary processing for obtaining flatness, which is advantageous in terms of manufacturing cost.

[0013]

EXAMPLE An example of the wet friction material of the present invention will be described with reference to FIGS. The wet friction material 1 of the example has a ring-shaped base material 2 and a ring-shaped base material 2 as shown in FIG. 1 showing a plane thereof and FIG. 2 showing an enlarged view of a section taken along the line AA of FIG. It is composed of two ring-shaped friction members 3 and 3 joined to both surfaces 20 of No. 2.

The ring-shaped base material 2 serves as a core metal of the wet friction material 1, and is made of pressed metal and has a thickness of 1.0 m.
m, outer diameter 130 mm, inner diameter 100 mm. The ring-shaped base material 2 has a plurality of inner peripheral side engaging projections (spline teeth) 21 for spline coupling provided at equal intervals on the inner peripheral portion. Each ring-shaped friction member 3 has a thickness of 0.7 m.
m, outer diameter 130 mm, inner diameter 110 mm. Each of the ring-shaped friction members 3 has a friction surface 30 of 330 μm.
It is formed of a minute uneven surface of m pitch (P). That is, the minute concave-convex surface is formed by alternately providing minute concave portions 31 and minute convex portions 32 concentrically. The vertical distance (h) from the bottom of the minute concave portion 31 to the peak of the minute convex portion 32 is about 110 μm.

The friction surface 30 of each ring-shaped friction member 3
Is molded by a hot press molding machine 4 as shown in FIG. The hot press molding machine 4 heats and presses two pre-manufactured intermediate materials 3a and the ring-shaped base material 2 arranged between them to manufacture the wet friction material 1. The friction surface 30 of the ring-shaped friction member 3 is also molded during the production of the wet friction material 1.

The intermediate material 3a is made of wood pulp as a raw material.
A mixed paper is manufactured using a mixture of silicon earth, organic fibers, a friction modifier, water and the like at a predetermined mixing ratio, and the mixed paper is impregnated with a thermosetting phenolic resin varnish by a dipping method and then added. After the volatile components are removed and the resin component is cured by temperature, it is punched into a ring shape. The hot press molding machine 4 has a lower mold 40 and an upper mold 45 that pressurize and heat an object to be processed to mold it. This lower mold 40 and upper mold 4
Reference numeral 6 has pressing transfer surfaces 41 and 47 in the shape of minute uneven surfaces for transfer, which are provided at the tips facing each other. Press transfer surface 41, 4
No. 7 has a triangular cross-sectional shape and a minute concavo-convex surface in which minute concave portions 42 and minute convex portions 43 of 330 μm pitch (P) are alternately formed in concentric circles and a triangular sectional shape of minute 330 μm pitch (P). It is a surface in which concave portions 48 and minute convex portions 49 are alternately formed in a concentric circle shape.

The minute convex portions 43 and 4 on each minute uneven surface
The distance in the vertical direction from the peak of No. 9 to the valley bottoms of the minute recesses 42 and 48 is 110 μm. The two intermediate materials 3
a and 3a are lower molds 4 of the hot press molding machine 4 shown in FIG.
0 and the upper mold 46, the ring-shaped base material 2 is arranged in the middle and sandwiched between both surfaces 20, 20. Next, the two intermediate materials 3a and 3a and the ring-shaped substrate 2
Is molded by being pressed at a predetermined pressure by the pressure transfer surface 41 of the lower mold 40 and the pressure transfer surface 47 of the upper mold 46 and heated at a predetermined temperature for a predetermined time.

As a result, the two intermediate materials 3a, 3
The friction coefficient a is adjusted to have a predetermined thickness, and the friction members 3 and 3 are joined to and integrated with both surfaces 20 and 20 of the ring-shaped base material 2, respectively. The friction surface 3 of the friction members 3, 3
At the time of the above-mentioned joining, the pressure transfer surfaces 41 and 47 have minute uneven surfaces of 330 μm pitch (P) transferred and molded on the surfaces 0 and 30.

The wet type friction material 1 (see FIGS. 1 and 2), which is manufactured in this way and is composed of the ring-shaped base material 2 and the friction members 3 and 3, is shown in FIG. As shown in the drawing, the slip test apparatus 5 is assembled inside the slip test apparatus 5 so as to be opposed to the two mating members 6, 6 and tested. The slip test device 5
Is a housing 50 that can seal the inside, and a housing 5.
0 an automatic transmission field (ATF) 51 enclosed inside, and an input shaft 52 and an output that are rotatably arranged on the same axis center line and each tip end is arranged in a housing 50. It is composed of a shaft 55 and a pressing piston 58.

A large diameter portion 53 is provided at the tip of the input shaft 52.
Are formed. The large diameter portion 53 has a spline groove 54 on the outer peripheral surface. A cylindrical portion 56 is formed at the tip of the output shaft 55 so as to face the outer peripheral surface of the large diameter portion 53 of the input shaft 50 at a predetermined distance. The tubular portion 56 has a spline groove 57 on the inner peripheral surface. Further, the mating member 6
Is a steel plate that is barrel processed to a surface roughness of 0.1.
The surface to be rubbed 60 is set to ˜1 μRa.

As a preparation prior to the test, the wet friction material 1 has its inner peripheral side engagement projections (spline teeth) 21 engaged with the spline grooves 54 of the input shaft 52. Further, the two mating members 6, 6 made of a metal plate have their outer peripheral engagement protrusions (spline teeth) 61 engaged with the spline grooves 57 of the engagement output shaft 55. Then, the slip test device 5 was operated under the following conditions to evaluate the slip operation of the wet friction material 1.

The slip operating condition is that the pressing piston 58 causes the friction surface 30 of the friction member 3 of the wet friction material 1 and the friction surface 60 of the mating member 6 to have a load pressure of 20 kg / cm ^2.
In while pressing, and a rotational speed N ₂ of the rotational speed N ₁ and the output shaft 55 of the input shaft 52, to obtain a slip operating condition of remembering rotational difference between N ₁ over N ₂ = 10 rpm. As a result, the measured torque value of stick-slip vibration was 5 kg · m.

As described above, in the wet friction material 1 of the embodiment, when the friction surface 30 of the friction member 3 is pressed against the friction surface 60 of the mating member 6 to transmit power by the slip operation, 330
Each minute convex portion 32 having a μm pitch contacts the surface to be rubbed 60 without variation in the entire area in the sliding direction. Therefore, the contact area between the friction surface 30 and the surface to be rubbed 60 does not change in the sliding direction, there is no variation in the surface pressure distribution, and the occurrence of discontinuous sliding is eliminated, so that stick-slip vibration and abnormal noise are generated. It can be reduced.

Further, the friction surface 30 of the wet friction material 1 of the embodiment
When the ring-shaped base material 2 and the two intermediate materials 3a, 3a are joined by the hot press molding machine 4, transfer molding can be performed as a minute uneven surface of 330 μm pitch (P). Since it is not necessary to perform secondary processing for obtaining flatness accuracy on the friction surface and the friction surface of the mating member, this is advantageous in terms of manufacturing cost.

Hereinafter, in order to confirm the effect of the wet friction material 1 of the example, a comparative example 1 in which a comparative test was performed using a wet friction material manufactured by a manufacturing process partially different from that of the example as a test sample, Comparative Example 2 in which a comparative test was performed using a mating member whose surface to be rubbed was processed is shown below. (Comparative Example 1) In the case of Comparative Example 1, when the wet friction material was manufactured, the ring-shaped base material 2 of the above-mentioned example and the ring-shaped base material 2 placed in the middle were sandwiched 2
It is the same as the case of the embodiment except that the lower die and the upper die having the flat pressing surface were used when the sheets of the intermediate materials 3a and 3a were joined by the hot press.

The wet friction material of Comparative Example 1 obtained had a visually flat friction surface, and the surface roughness was measured with a roughness meter. 1
It had irregularities with a pitch of 0 to 20 μm. Using the wet friction material of Comparative Example 1, slip evaluation was performed in the same manner as in the example.
As a result, the measured torque value of the stick-slip vibration is 14 which is larger than 5 kg · m in the case of the embodiment.
It was kg · m.

(Comparative Example 2) In the case of Comparative Example 2, the wet friction material produced in Comparative Example 1 and a partner whose surface to be rubbed was subjected to a flat surface polishing treatment to improve its flatness to 0.02 mm Slip evaluation was performed using the member. As a result, the measured torque value of the stick-slip vibration was 9 kg · m, which is larger than the value of 5 kg · m in the example.

Therefore, it has been found that the wet friction material 1 of the embodiment can reduce stick-slip vibration.

[Brief description of drawings]

FIG. 1 is a plan view showing a wet friction material according to an embodiment of the present invention.

FIG. 2 is an enlarged view taken along the line AA in FIG.

FIG. 3 is a perspective view showing a manufacturing process of the wet friction material in FIG.

FIG. 4 is a cross-sectional view showing a usage state of the wet friction material in the example.

[Explanation of symbols]

1 ... Wet friction material 2 ... Ring-shaped base material 20 ... Both surfaces 21
... Inner peripheral side engaging projection 3a ... Intermediate material 3 ... Ring-shaped friction member 30 ... Friction surface 31 ... Micro concave portion 32 ... Micro convex portion 4 ... Heat press molding machine 40 ... Lower mold 41
Press transfer surface 46 Upper mold 47 Press transfer surface 5 Slip tester 50 Housing 51 Automatic transmission field (ATF) 52 Input shaft 53 Large diameter part 5
4 ... Spline groove 55 ... Output shaft 56 ... Cylindrical part 5
7 ... Spline groove 58 ... Hydraulic piston 6 ... Mating member 60 ... Friction surface 61
... Outer peripheral side engagement protrusion

Claims (1)

[Claims] 1. A wet friction material comprising: a ring-shaped base material; and a friction member having a friction surface that is joined to the ring-shaped base material and that is pressed against a friction surface of a mating member that relatively rotates. The wet friction material is characterized in that the friction surface of the friction member is a minute uneven surface having a pitch of 100 to 1000 μm.