JPS6272942A - Cork friction material - Google Patents

Abstract

PURPOSE:To make a large quantity of oil impregnable as well as to improve a frictional characteristic, by heating and burning a cork friction material, while burning and destroying a weak structural part, and having oil impregnated in this destroyed part. CONSTITUTION:A molded cork friction material is heated and burned, burning and destroying each bladder nucleus of cork particles in the friction material or a weak structural part of a filler or the like of a bonding agent partially, and oil is impregnated in a part where the structure prior to the said destruction has been occupied or the inside of the bladder whose nucleus is destroyed by means of vacuum impregnation. At this time, an important action for impregnat ing the oil is forcedly performed by a vacuum process, and if the friction mate rial is dipped in the heated oil, a large quantity of oil is impregnable in a short time.

Description

[Detailed Description of the Invention] [Industrial Applications] The present invention significantly improves the abrasion resistance of cork without substantially impairing its frictional properties, and also improves cork impregnation with oil. Regarding friction materials.

[Conventional technology]

Natural cork, which has an excellent coefficient of friction, is used as the friction material that is often used in clutches for industrial sewing machines, motor clutches, brake shoes, and the like. Conventionally, in order to form this cork friction plate, the manufacturing method generally used is to crush natural cork bark and compressively bond the bark with an adhesive.

However, cork has low physical strength, and when the clutch or brake is activated, it may make noises and generate unpleasant odors due to frictional heat.
Furthermore, there were drawbacks such as shortened life due to abnormal wear caused by half-clutching, etc.

Therefore, as a method to solve this problem, oil is impregnated into the intergranular spaces of a cork friction material made by integrally molding cork particles via an adhesive, thereby improving the wear resistance.

[Problem that the invention seeks to solve]

However, the cork friction plate uses phenol-1 fat as an adhesive.
Because the cork particles were compressed and bonded using adhesives such as epoxy resin, urea resin, and vinyl acetate resin, there were very few voids between each cork particle and the adhesive, and this was impregnated with vacuum or pressure at room temperature or heating. Even if oil is impregnated by this method, the amount of oil impregnated is extremely small, less than 10%, and the desired improvement in wear resistance cannot be obtained much. When used, the oil on the surface is removed in a short period of time, leaving only a small amount of oil remaining inside, resulting in a significant drop in wear resistance.

For this reason, as a method to increase the amount of oil impregnated, cork particles and oil are mixed and stirred in advance to make the oil adhere to the cork particles, and then phenolic adhesive etc. is mixed, stirred, and fixed in a mold. A method was devised to obtain a cork friction material in one piece. However, although the amount of oil impregnated in this material is certainly higher than that of the cork friction material mentioned above, the adhesive force is significantly reduced because the oil that prevents the adhesive from adhering is attached to the entire outer surface of the cork particles. There is a high risk that the cork friction material will be destroyed under harsh conditions such as clutch facings and brake shoes where strong force is applied, and stirring the cork particles, oil, and adhesive takes time and requires uniform stirring. However, there were disadvantages such as it being difficult to use and also having problems in terms of strength.

The present invention eliminates these drawbacks and provides a cork friction material that is easy to work with, has a large amount of oil impregnated, and has oil impregnated not only on the surface but also in the center.

[Means for solving problems]

The present invention is a cork friction material obtained by integrally molding cork particles having an appropriate size, substantially 10 to 80 mesh, with an adhesive, and in which oil (including but not limited to vegetable oil or mineral oil) is added. The cork friction material is impregnated, and the formed cork friction material is fired using a heating device such as a heat press or an oven to partially destroy the structure of the cork particles and adhesive layer inside it, and then the cork friction material is heated. It is characterized in that the tissue-destroyed area is impregnated with oil by immersing it in warm oil and applying vacuum.

[Effect]

The present invention makes it possible to impregnate a large amount of oil into a compression-molded cork friction material that has very few voids that can be impregnated with oil, and this was achieved for the first time by firing the cork friction material. be.

In other words, approximately 75% of the volume of cork is air, but this air is wrapped in resin and maintains the shape of independent air cells.
It has almost no voids that can be impregnated with oil. Of course, the same applies to adhesives, and after bonding, cork particles do not have as much space as desired.

Therefore, in the present invention, the molded cork friction material is heated and fired to partially destroy the weak tissue parts such as the air vesicle shells of the cork particles or the filler of the adhesive, and the structure before the destruction is removed. This method uses vacuum impregnation to impregnate oil into the occupied part or into the broken air vesicles of the shell. At this time, the important action of impregnating the oil is forcibly performed by a vacuum process.
By heating the cork friction material to 100°C to 100°C and immersing it in oil, a large amount of oil can be impregnated in a shorter period of time, making it possible to impregnate clutch facings and brakes that require large amounts of oil that could not be impregnated with conventional methods. Cork friction material suitable for use in shoes, etc. (specifically, a material with a weight ratio of 25 to 30 to cork particles)
Cork friction material impregnated with oil of % weight ratio can be easily obtained.

In addition, the amount of oil impregnated should be 15-50% depending on the purpose and application of the cork friction material, and optimally 25-30%.
According to the present invention, this value can be easily obtained by controlling the firing temperature and degree of firing.

〔Example〕

Next, the present invention will be explained by examples.

Use cork particles with a size of about 20 to 70 mesh, add adhesive to this, stir for 5 to 1 minute, put the desired amount into a mold, heat and compress, and then remove from the mold. Take it out to obtain a cork friction material in the desired shape. This molded cork friction material is baked in a press heated to 150°C to 170°C for 20 to 50 minutes, and then heated to 75°C.
The cork friction material was immersed in turbine oil #20 heated to 85°C to 85°C and vacuum impregnated with 311111Hy for 40 minutes to obtain a cork friction material having an oil weight ratio of 41.0% by weight.

With this method, it is possible to impregnate oil up to 55% by weight by adjusting the degree of calcination, vacuum impregnation time, etc.

In carrying out the present invention, it is also possible to attach the cork friction material to a metal substrate of a clutch, brake, etc. in advance and then impregnate it with oil, thereby increasing the adhesive strength between the cork and the metal substrate. Moreover, clutch facings and brake shoes with excellent friction characteristics can be easily obtained.

〔Effect of the invention〕

In this way, the action of the oil impregnated according to the present invention significantly improves the wear characteristics without impairing the friction coefficient, making it possible to maintain the life of the cork friction material for a long time, and in addition, the oil distribution is almost uniform. Therefore, cork friction material obtained by machining by cutting from a block has the same effect, and is an excellent cork friction material that cannot be obtained by conventional methods.

Claims (2)

[Claims] (1) In a cork friction material formed by integrally molding cork particles via an adhesive; the formed cork friction material is heated and fired to partially destroy the structure of the cork particles and adhesive layer inside it. 1. A cork friction material characterized in that the cork friction material is immersed in heated oil and vacuum is applied to impregnate the tissue-destroyed portion with oil. (2) The cork friction material according to claim 1, wherein the oil is impregnated in an amount of 15 to 50% by weight based on the weight of cork.