JPH0464551B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a clutch friction material, particularly a wet friction material suitable for use in an oil solution.

[Conventional technology]

For example, the clutch that transmits the drive from the prime mover to the transmission in automobiles, construction machinery, agricultural machinery, motorboats, etc., transmits sufficient power at all times, but when starting, it provides a moderate amount of slippage, and the clutch of the transmission A function is required to cut off the power when switching. Friction type clutches are widely used as clutches that satisfy this function. Friction type clutches include dry type clutches that are used in dry conditions and wet type clutches that are used in oily liquid. The latter wet clutch is often used in the form of a multi-disc clutch as a component in planetary gear type automatic transmissions.

The friction plate of the wet clutch is
As shown in FIG. 1 (exploded view), a friction material 11 called a paper facing is pasted on both sides of a core bar 12. The friction agent 12 is made by impregnating a base material of cellulose with an inorganic filler such as graphite, asbestos, or ceramic, or an organic filler such as cashew dust, and a thermosetting resin such as a phenolic resin or a melamine resin. . Such materials have a high coefficient of friction, are highly elastic, and are porous, so they have a good oil absorption rate, so they are currently used in large quantities as the best wet friction materials.

Friction type clutches generate frictional heat, so
In order for the above-mentioned functions to be stably performed, heat must be efficiently released from the frictional parts. In wet clutches, oil plays an important role as a heat transport medium. The heat generated on the friction surface is diffused and released throughout the system 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, there will be no heat release and overheating will occur, causing thermal deterioration of the friction material and oxidation and decomposition of the oil, resulting in a decline in its function as a friction material. . To prevent such a situation, grooves 13 (see FIG. 11) are provided on the surface of the friction material through which oil can circulate. Wet friction materials with such grooves are described in Japanese Patent Application Laid-Open No. 56-90135, or pages 56-57 of NSK Bearing Journal (published by NSK Warner Co., Ltd.) No. 638 (published in 1979). has been disclosed. As described in these documents, the grooves are formed by pressure molding or cutting.

On the other hand, Japanese Patent Laid-Open No. 148028/1983 discloses a method of manufacturing paper material by adding a watermark pattern by the so-called pressed mark method. As shown in FIG. 12, paper is made by a fourdrinier paper machine 1.
The paper stock in head box 3 is Prestrol 5.
The water flows out onto the endless fourdrinier 4 stretched over the couch roll 6, and the water is removed while the fibers are dispersed. The dandy roll 9 rotates while contacting several animals 2.
When watermarks are to be placed on several fish 2, the surface of the dandy roll 9 is provided with irregularities of a desired shape. Note that 7 is a table roll and 8 is a suction box. The present invention was made based on the knowledge of such paper making methods.

[Problem that the invention seeks to solve]

When grooves are formed in the friction material by the above-mentioned processing and forming process, the depth of the grooves formed is only about half the thickness of the friction material, which may be insufficient. In addition, there is a drawback that the molding surface is under high pressure and a large amount of resin is impregnated, which prevents oil from entering and exiting. On the other hand, forming grooves by cutting requires a large number of processing steps and becomes expensive. The resulting grooves have cutting debris attached to them and fluff on the edges of the grooves, which get mixed into the oil during use and cause problems such as valve stays. In addition, the friction material sometimes chipped or partially peeled off. Wet friction materials obtained by providing grooves on the surface by these methods have not yet achieved sufficient performance.

The present invention solves the above-mentioned drawbacks and problems of conventional wet-type friction materials, and enables the production of wet-type friction materials in large quantities and at low cost, which allows sufficient oil circulation even without grooves and has sufficient mechanical strength. This is the way to do it.

[Means for solving problems]

Means for achieving the above object will be explained with reference to FIG. 1 (manufacturing process diagram) corresponding to the embodiment.

In the first step, an aqueous dispersion 30 containing cellulose 20 and a filler 26 is applied to several cylinders 32 (convex portions 32a, second
(see figure). In the second step, the surface of the paper web 35 is pressed with press rolls 37a and 37b (see FIG. 3). In the third step, several animals 35 are dried using dryers 39, 41, and 42. In the fourth step, the paper base material obtained in the third step is cut by a cutting machine 49. The fifth step is to impregnate and harden the thermosetting resin 51 after the first step.

[Effect]

Since the uneven member 32 is brought into contact in the first step,
Irregularities 35a, 35b on the surface of several animals 35 being made into paper
is formed (Figure 2). In the second step, the surface unevenness 35a, 35b of the paper web 35 (shown by chain lines in FIG. 3)
is pressed into a flat surface. At this time, the convex portion 35
b is pressed more than the concave portion 35a, resulting in a layer 16 with a lower porosity. In other words, layers 1 with different porosity
Get some 35 with 6 and 17. A wet friction material 15 (see FIG. 6) is obtained through the third step (drying), fourth step (cutting), and fifth step.

The obtained wet friction material 15 has a base material containing cellulose and a filler, and is impregnated with a thermosetting resin. The base material has a layer 16 with low porosity (layer with high density, shown as spots) and a layer 17 with high porosity (layer with low density, shown in white), and the friction surface is flat.

〔Example〕

Hereinafter, embodiments of the manufacturing method to which the present invention is applied will be described in accordance with the process diagram shown in FIG.

As shown in the figure, first, a cellulose raw material 20 such as wood is pulverized by a raw material dissociator (pulper) 21 . The resulting raw material pulp is beaten in a beater 22 while adding a large amount of water. The resulting beaten liquor is stored in a storage tank 23 and then passed through a dust remover 24, and then its concentration is adjusted in a concentration box 25.
10 to 50 parts by weight, preferably 20 to 40 parts by weight, of an inorganic filler and an organic filler 26 are added to the beating liquid based on 100 parts by weight of the pulp, and the mixture is thoroughly mixed using a stirrer 28 to obtain an aqueous dispersion 30. These fillers are added to improve friction performance and heat resistance.
For example, barium sulfate, kaolin, clay, calcium carbonate, silicic acid, alumina, diatomaceous earth, asbestos, graphite, ceramic, etc. are used singly or in combination. In addition, organic fillers are used singly or in combination in the same way as in cashew dust.

Paper is made from the aqueous dispersion 30 obtained above using a circular mesh paper machine while adding a watermark pattern using the watermark method. Aqueous dispersion 30
is placed in the papermaking tank 31. Round mesh cylinder 3
2. Endless felt belt 33, couch roll 3
4, paper is made by a conventional method. A in this part
FIG. 2 is an enlarged view of the -A cross section. A projection 32a corresponding to the watermark pattern to be inserted is provided on the surface of the cylinder 32. The surface of the paper web 35 is depressed by the protrusion 32a, resulting in a thinner part (recess) 35a and a thicker part (protrusion) 35b.
A pattern is formed on the uneven surface. Next, an aqueous solution 51 of phenolic resin is sprayed onto the paper web 35 using a sprayer 50 . At this time, since the paper web 35 is in a wet state, it is compatible with the resin solution.

In this state, the paper web 35 advances in the direction of the arrow and is sandwiched between press rolls 37a and 37b and pressurized. FIG. 3 is an enlarged view of the BB cross section of this portion. Convex portion 35b of the paper web 35 as shown by the chain line in the same figure.
The surface of the recess 35a is pressed flat by the surface of the press roll 37b. The convex portion 35b is the concave portion 35a
The layer 16 is pressed more and has a higher density of the base material and a lower porosity. The concave portions 35a are not pressed much and the density of the base material does not change much, resulting in a layer 17 with a high porosity. In other words, layer 1 with high porosity
7 becomes the watermark pattern part of the paper web 35.

The paper web 35 with a watermark pattern is dried on a dryer roll 39 and then transferred to size rolls 40a and 40b.
The sizing process is carried out using dryer roll 4.
1 and 42 to be completely dried. Through these drying steps, the impregnated phenolic resin is heated and hardened. Next, it is wound around a reel 44 under tension by a tension roll 43 to obtain a rolled paper base material 46. The roll-shaped base material 46 is cut with a single cutter 47 to form a sheet-shaped paper base material 4.
8 and is put through the cutting machine 49.

As shown in FIG. 4, the sheet is aligned with the vertical and horizontal patterns of the watermark on the sheet-like base material 48, and is punched and cut into a ring shape that is the shape of a wet friction material. In this way, a wet friction material 15 having layers 16 and 17 with different porosities as shown in FIG. 6 is obtained.

Note that the impregnation with the resin may be performed after punching.

FIG. 5 shows another example of punching, in which a sheet-like paper base material 52 of a wet friction material is punched into a 1/4 arc 53 having protrusions 53a and depressions 53b. Wet type friction material 15 can be obtained by combining four of the 1/4 arcs 53 with protrusions 53a and depressions 53b. In this case, even if the watermark pattern on the base material 52 is unidirectional, the wet friction material 15 has vertical and horizontal watermark patterns. Also, the base material 5
It is also possible to reduce waste (uncut portions) in step 2.

7 to 9 show various embodiments of the wet friction material 15 to which the present invention is applied. The layer (watermark pattern) 17 with high porosity is curved (Fig. 7), unidirectional (Fig. 8), and cross-shaped (Fig. 9).
It is. Also, without being limited to these shapes,
It can be made into various shapes.

The wet friction material 15 obtained as described above is laminated on both sides of the core metal 12 (see FIG. 11).
It becomes a friction plate for a wet clutch.

Experiments and Results Experiments conducted to evaluate the performance of the wet friction material of the present invention and their results will be described below.

≪Prototype≫...An aqueous dispersion prepared by adding 30 parts of an inorganic filler and an organic filler to 100 parts by weight of wet friction material linter pulp produced by the method of the present invention. The paper is made so that the density of the layer) is 0.3 g/cm ³ and the density of the watermark part (layer with high porosity) is 1/2, 0.15 g/cm ³ .
Watermark width 2mm, pitch 10mm. A wet friction material is made from this paper base material.

≪Comparative product 1≫... A wet friction material is made from a paper base material that is made from the same raw materials as the conventional wet friction material/grooveless prototype and has the same density as the base portion of the prototype.

≪Comparative product 2≫...Conventional wet friction material with grooves Grooves with a width of 2 mm and a pitch of 10 mm are cut into a wet friction material made the same as comparative product 1.

The three types of wet friction materials mentioned above were tested for durability using an SAE No. 2 friction tester. This test repeatedly absorbs the energy of a rotating body rotating with inertia (friction stops the inertial rotation), and examines the cycle until the surface of the friction material burns due to the absorbed energy and turns black. be. A graph of the test results is shown in FIG. In the figure, the horizontal axis is the absorbed energy (Cal/cm ² ) per unit area of the friction surface of the friction material, and the vertical axis is the cycle (times) until blackening due to the absorbed energy, that is, the thermal durability cycle (times). As can be seen from this graph, the thermal durability cycle of the prototype is clearly better than that of Comparative Product 1 and approximately equal to Comparative Product 2. However, with Comparative Product 2, some layers peeled off during this test, some groove edges chipped off, and fine debris got mixed into the oil. This was not the case with the prototype.

〔Effect of the invention〕

The wet friction material obtained by the method of the present invention is
Since the layer has a high porosity, oil can circulate through the layer, cooling the friction surfaces sufficiently and creating a clutch that does not seize. Since the friction surface is flat, it is strong and free from the risk of layer peeling or chipping unlike conventional wet friction materials with grooves formed by cutting. This eliminates the possibility of cutting chips accumulating in the oil and causing problems such as valve stays. Moreover, since layers with high porosity and layers with low porosity are formed during the papermaking process, it can be made at low cost. In wet friction materials with grooves formed by pressure molding, the groove depth is limited, but according to the method of the present invention, the porosity of the layer with high porosity corresponding to the grooves can be selected quite freely. Also, the porosity of the entire base material is not increased, but because there are many layers with low porosity, mechanical strength is maintained there, and even if the thickness is reduced, the material is strong overall.

As explained above, the method of the present invention can form a layer with high porosity on the friction material using a watermarking method different from the conventional prestomark method, and the resulting wet friction material is durable even if it is thin and does not seize. It becomes something that has sex.

[Brief explanation of the drawing]

Fig. 1 is a manufacturing process diagram of a wet friction material to which the present invention is applied, Fig. 2 is an enlarged cross-sectional view of the A-A cross section, Fig. 3 is an enlarged cross-sectional view of the B-B, and Fig. 4 and Fig. 5 are the raw materials. Figure 6 is a perspective view of the manufactured wet friction material, Figures 7 to 9 are plan views of various embodiments of the wet friction material, and Figure 10 is the wet friction material. Fig. 11 is an exploded perspective view of a friction plate using a wet friction material, and Fig. 12 is a diagram showing the manufacturing process of a conventional paper material. 11, 15... Wet friction material, 12... Core metal, 1
6... Layer with low porosity, 17... Layer with high porosity, 20... Cellulose raw material, 26... Filler, 3
0...Aqueous dispersion, 31...Paper making tank, 32...Cylinder, 32a...Protrusion, 33...Felt, 3
4...couch roll, 35...several, 35a...
Concave portion, 35b... Convex portion, 37a, 37b... Press roll, 48... Paper base material, 49... Cutting machine,
51...Phenol resin solution.

Claims (1)

[Scope of Claims] 1. A step of bringing an aqueous dispersion containing cellulose and a filler into paper making contact with a concavo-convex member to form an uneven surface of a paper web to be made; A step of pressing the surface of a certain paper web to make it a flat surface and forming layers with different porosity, and a step of drying the paper web with the formed layers of different porosity to obtain a paper base material. It is characterized by comprising a step of cutting the obtained paper base material into a predetermined shape, and a step of impregnating and curing a thermosetting resin after the step of forming the surface of the paper web into irregularities. Method for manufacturing wet friction material.