JPH0953675A - Manufacture of friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent separation and displacement from being caused during a process due to floating, warping, etc., in a friction material of two-layer structure, in the case of performing a process of binder impregnation, drying and hardening by superposing two sheets of the friction materials. SOLUTION: Two sheets of friction materials 60A, 60B are superposed one over the other into a two-layer structure, and its edge part 67 is brought into pressure contact by press upper/lower molds 72, the edge part 67 is attached under pressure and fixed. As a fixing means, in addition to this mold, stapler bonding agent, paper clip, inserting, seaming, etc., are listed.

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 plate used for a clutch, a brake, etc. in a friction engagement device.

[0002]

2. Description of the Related Art FIG. 8 shows an example of the basic structure of a wet friction engagement device. A drive plate 2 fitted to a spline portion 51 of a hub 5 fitted to an input shaft 6 and a retainer 4 are shown. The torque is transmitted by the contact of the passive plate 1 fitted to the spline portion 41. In the figure, 3 is a pressure plate, and 7 is a pressing piston.

FIG. 9 is a perspective view of a passive plate and a drive plate, and FIG. 10 is a side sectional view of the combined state. The passive plate 1 is composed of a steel plate portion 11 and spline protrusions 12, and the drive plate 2 is a steel plate portion 21. It comprises a spline projection 22 and a wet friction material 23 adhered to both sides of the steel plate portion 21.

In view of current energy and environmental problems, the friction engagement device is small and lightweight, has a high torque capacity, and at the same time has a small operational shock in terms of riding comfort and is self-excited by a judder or the like. No vibration is required. In addition, it is necessary to simultaneously cope with the increase in energy associated with the increase in the rotation speed and the output of the automobile engine, and the demand is extremely high. In the conventional friction engagement device, in order to reduce fuel consumption and operation shock, the continuous slip state of the clutch during traveling is expanded, the clutch efficiency is changed, the engine is controlled when the clutch is engaged, and input is performed. Many advanced controls are being adopted, such as lowering the torque / clutch capacity ratio.

Wet friction materials include fiber base materials such as natural pulp fibers and organic synthetic fibers, fillers such as diatomaceous earth and cashew resins, friction modifiers and binders such as thermosetting resins. The binder inside the friction formed a high-concentration impregnated layer (strong binder layer) on the surface layer and the back layer (that is, the surfaces on both sides). As an example of the binder, a thermosetting resin is a material that generally constitutes a wet friction material (composite fiber paper), and as this type of resin, a phenol resin, an epoxy resin, a urea resin, a melamine resin, a silicone resin, or the like is used. Applicable Further, as the above-mentioned wet friction material, a paper-making type is known, and the friction material uses a natural pulp fiber, an organic synthetic fiber, or the like as a fiber base material, and a filler and a friction modifier are mixed in the friction material to produce a raw material. A friction material is manufactured by making paper, impregnating the raw paper with a diluted thermosetting resin solution, volatilizing a diluting solvent in a drying step, and then heat-curing the resin.

Explaining the impregnation of the binder and the drying step further, first, when impregnating the raw paper, the binder is diluted with an organic solvent and used. After the diluted binder is sufficiently impregnated inside the raw paper, the organic solvent is volatilized in the drying step. However, due to the surface tension, a surplus binder film and a layer with a high binder concentration are formed on the outer surface layer (about 100 μm) of the friction material surface, and the binder distribution in the thickness direction of the friction material is concentrated on the outer surfaces of the front and back layers. It was unavoidable that a high binder layer was formed. Here, the back surface or the back layer is not the friction surface but the surface on the side opposite to the friction surface, which is the side bonded to the steel plate.

Thus, the physical properties of the binder (surface tension)
It has been found that the influence of the surplus binder film formed on the outermost surface layer of the friction material and the layer having a high binder concentration causes various problems described below.
(1) The binder film coated on the fiber substrate of the outermost surface layer in the initial state is hard, lacks flexibility, and also forms minute projections, so it is not always smooth, and when viewed microscopically, the passive plate The contact with the sliding surface forms the sliding surface only by the protruding portion of the binder. Therefore, the contact area is small, and the friction coefficient between the binder and the passive plate is originally low, so that the initial friction coefficient is low.

As the sliding is repeated, the binder is abraded, and the flexible fiber base material appears on the sliding surface, so that the contact portion becomes large and large and smooth, and the fiber base material has a high friction coefficient. The coefficient of friction increases due to the appearance of the on the surface. This is a factor of the initial familiarity that shows the change in the friction coefficient. (2) Since there are many binders on the surface layer, which lacks flexibility and lacks smoothness, the contact with the passive plate becomes uneven, and the wedge effect of the oil film occurs microscopically, which deteriorates the operation shock and the judder property. It is a factor.

(3) The binder concentration is high on the surface layer, which is a factor that the friction material is apt to be plasticized due to a rapid temperature rise. This familiarity is regarded as a major quality problem because the initially set torque capacity changes in a short time, especially from the time of new product.

The problem with the product is that if the clutch capacity is designed with a low friction coefficient of a new friction material, a high torque capacity after fitting due to a time-series change of the friction coefficient is an operational shock. Will be the cause of. In expensive high-end vehicles, extra learning functions were sometimes added to the control. In addition, the low friction coefficient of a new product causes the surface temperature to rise further due to the frictional heat accompanying the extension of the sliding time in a harsh driving environment, and there is a large amount of binder in the surface layer. The binder on the surface promotes the phenomenon of rehardening or carbonization due to frictional heat and the friction surface becoming a mirror surface), which causes a fade phenomenon and an extreme decrease in the friction coefficient, which causes heat resistance and durability problems. Become. As another phenomenon, the additive inside the lubricating oil decomposes and deposits due to frictional heat and adheres to the friction material surface and the mating sliding surface, clogging the friction material surface, and the original performance is not exhibited. In some cases, a similar decrease in friction coefficient may be caused.

As measures against these problems, the actuating pushing force may be increased and the sliding time may be shortened, but the peeling life is shortened due to repeated compression fatigue due to high surface pressure, and the heat generation rate per unit time is increased. There are many problems such as generation of heat spots on the friction surface (passive plate), thermal deformation, upsizing of a hydraulic pump for generating high hydraulic pressure, and problems such as leakage of hydraulic oil concerning durability life.

In addition, when the impregnated amount (concentration) of the binder is increased to improve the peeling life of the friction material and the strength of the friction material is improved, the friction characteristics (operation shock, judder performance) due to lack of flexibility of the friction material Deterioration, further deterioration of the conformability that shows the change of the friction coefficient at the time of new article and after engaging experience due to the influence of the binder on the surface of the friction material, and on the other sliding surface due to the fact that the composition of the fibers on the surface is strengthened by the binder There have been many problems such as the transfer of the additive to the friction material by scraping off the additive of the lubricating oil to be adsorbed and the reduction of the friction coefficient. Many of these problems are caused by the excess binder film formed on the outermost surface layer of the friction material and the layer containing a large amount of binder (having a high concentration) as described above when the product is new. Is there.

As a countermeasure against these problems, the excess binder coating on the surface layer of the friction material is reduced by sliding for a certain period of time,
The surface of a new friction material is cut and processed (see Japanese Patent Laid-Open No. 5-99297).
No.) An attempt was made to remove the excess binder coating, but the durability life was remarkably shortened due to the reduction in strength due to fiber breakage and the like. In addition, smoothing of hot plates (Shokai 62-149)
No. 629) to carbonize the surface of the friction material, or forcibly smooth the surface, but in the former case, the life is shortened due to the strength reduction due to carbonization of the fiber,
Although the latter becomes smooth, it does not lead to the removal of the surplus binder film, it does not become a drastic measure against the fade phenomenon and judder performance, and the problem that it leads to an increase in product price is inevitable. Therefore, as a method of preventing excess binder that forms on the extreme surface layer due to surface tension, two friction materials of the same material (different materials, even if the thickness may be different) are layered, fully impregnated with diluted binder, and then dried. After the process, heat is applied in the curing process while the two sheets are superposed. After the completion of the curing process, the two friction materials are separated. When the friction materials are in close contact with each other, the surface tension does not move on the inner surfaces that are in close contact with each other.Therefore, a surplus binder layer cannot be formed like the conventional surface. It is also possible to obtain a friction material that prevents formation of a layer having a high binder concentration. And, in the curing process, the inner surface adhered has flexibility more than the surface directly receiving heat,
By simultaneously performing molding and bonding, which consists of pressurization and heating, on the friction material using a hot plate or the like, smoothness of the flexible surface can be promoted and a friction material having a good smooth surface can be obtained.

[0014]

As described above, when impregnation, drying and curing are performed by superposing two friction materials, if they are not fixed, the two-layer structure floats and warps in the impregnation, drying and curing steps. Due to such a phenomenon, peeling or deviation occurs, an excess binder film due to the surface tension of the binder and a layer with a high binder concentration are formed, and in the curing step,
Since it is directly exposed to heat, it loses its flexibility and does not form a good smooth surface, which inevitably results in the inability to achieve the intended action and effect.

[0015]

SUMMARY OF THE INVENTION In order to solve the above-mentioned drawbacks, the present invention uses a stapler, an adhesive, a paper clip, an insert, a stitch, and
The method for manufacturing a friction material is characterized in that the friction material is fixed by pressure bonding using a compression press. By this fixing means, the friction material having a two-layer structure by superposing two sheets is
In the impregnation, drying, and curing steps, there is no peeling or peeling due to warping and the like, and there is no deviation, and the intended action and effect can be achieved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a case in which two friction materials 60A and 60B are superposed and fixed by a stapler 61 with their edges spaced at predetermined intervals. FIG. 2 shows the edge portion 62 fixed with an adhesive. FIG. 3 shows the edges fixed with paper clips 63 at predetermined intervals. FIG. 4 shows fixing by insertion, (A) shows the cut-raised pieces 64 provided at predetermined intervals on the edge of the upper friction material 60A, and (B) shows the corresponding location of the lower friction material 60B. The slit 65 is shown in the figure. (C) shows a state in which the cut-and-raised piece 64 of the friction material 60A is inserted into the slit 65 of the friction material 60B below and both are fixed by insertion. FIG. 5 shows that the friction materials 60A and 60B are sewn and fixed with a thread 66 at predetermined intervals. FIG. 6 shows that the friction materials 60A and 60B are fixed at the edge portion 67 by pressure bonding with a compression press. FIG. 7 shows the state during pressing, and the friction materials 60A, 60
The edge 67 of B is shown being pressed by the upper die 71 and the lower die 72 of the press.

[0017]

The present invention has the above-mentioned structure and
The two-layer structure of the friction materials that are stacked on top of each other does not cause peeling or slipping due to floating or warping during the manufacturing process, thus preventing the formation of an excess binder coating and a layer with a high binder concentration on the surface layer, and making the surface layer flexible. It has the effect of producing a friction material that is rich and has good smoothness.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of fixing with a stapler.

FIG. 2 is a diagram showing an example of fixing with an adhesive.

FIG. 3 is a diagram showing an example of fixing with a paper clip.

FIG. 4 is a diagram showing an example of fixing by inserting.

FIG. 5 is a view showing an example of fixing by suturing.

FIG. 6 is a diagram showing an example of fixing by crimping.

FIG. 7 is a view showing a state during pressure bonding with a press.

FIG. 8 is a side sectional view of an example of a wet friction engagement device.

FIG. 9 is a perspective view of a passive plate and a drive plate.

FIG. 10 is a side sectional view showing a state where the friction plates are assembled.

[Explanation of symbols]

 1 Passive plate 11 Steel plate part 12 Spline protrusion 2 Drive plate 21 Steel plate part 22 Spline protrusion 23 Friction material 3 Pressure plate 4 Retainer 41 Spline part 5 Hub 51 Spline part 6 Input shaft 7 Pressing piston 60A Friction plate 60B Friction plate 61 Stapler 62 Adhesion Agent 63 Paper clip 64 Cut and raised piece 65 Slit 66 Thread 67 Crimping part 71 Press upper mold 72 Press lower mold

Claims (7)

[Claims] 1. When manufacturing a friction material containing a fiber base material such as natural pulp fiber or organic synthetic fiber, a filler such as diatomaceous earth or cashew resin, a friction modifier and a binder such as thermosetting resin, During the steps of binder impregnation, drying, and curing,
In order to prevent excess binder from adhering to the surface layer of the friction material and to obtain a smooth and flexible friction material surface, two friction materials are superposed, and the binder is impregnated, dried and cured. In the method for producing a friction material, which is configured to separate after performing each of the steps, the method for producing a friction material, characterized in that the two friction materials that are overlapped are fixed. 2. The method for manufacturing a friction material according to claim 1, wherein the fixing means is a stapler. 3. The method of manufacturing a friction material according to claim 1, wherein the fixing means is an adhesive. 4. The method of manufacturing a friction material according to claim 1, wherein the fixing means is a paper clip. 5. The fixing means is insertion engagement in which a cut-and-raised piece of the other friction material is inserted into a slit provided in an edge portion of the one friction material. Manufacturing method of the friction material. 6. The method for manufacturing a friction material according to claim 1, wherein the fixing means is suture using a thread. 7. The method for manufacturing a friction material according to claim 1, wherein the fixing means is pressure bonding using a compression press.