JPH0467050B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a cork friction material that substantially improves the wear resistance and increases the amount of oil impregnated without impairing the frictional properties of cork. Regarding.

[Conventional technology]

Natural cork, which has an excellent coefficient of friction, is used as a friction material for clutches of industrial sewing machines, clutch facings of motors, brake shoes, etc. 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 has disadvantages such as making noise when the clutch or brake is activated, producing a strange odor due to frictional heat, and shortening the service life due to abnormal wear caused by a partially engaged clutch.

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, since the cork friction plates used adhesives such as phenolic resin, epoxy resin, urea resin, and vinyl acetate resin to compress and bond the cork particles, there are very few voids between the cork particles and the adhesive. Even if this is impregnated with oil by vacuum or pressure impregnation at room temperature or heating, the amount of oil impregnated is extremely small, less than 10%, and the desired improvement in wear resistance cannot be obtained much. When oil is impregnated, only the surface of the friction material is impregnated, so when it is used, the oil on the surface is removed in a short period of time, leaving only a small amount of oil inside, resulting in a significant drop in wear resistance.

Therefore, 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 a phenolic adhesive etc. is mixed in, stirred and put into a mold. A method of obtaining cork friction material as a fixed and integrated material was considered. 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. Under harsh conditions such as clutch facings and brake shoes, where strong forces are applied, there is a high risk that the cork friction material will be destroyed, and stirring the cork particles, oil, and adhesive takes time and requires uniform stirring. However, there were drawbacks such as difficulty in applying the material and problems with 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 relates to 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. A cork friction material that is impregnated with an adhesive and water, which is obtained by mixing and stirring cork particles with an adhesive and water, then coagulating them together via an adhesive, and immersing the cork friction material in heated oil. At the same time, vacuum is added to evaporate the water contained in the cork friction material,
It is characterized by replacing the moisture with oil and impregnating it with oil.

[Effect]

The present invention makes it possible to impregnate a cork friction material made of cork grains and an adhesive with very few voids capable of impregnating oil with water, and use the water to uniformly impregnate the interior with a large amount of oil. Its function is to disperse and mix a large amount of water with the adhesive in advance before forming the cork friction material, and to form the cork friction material using a conventional method. Thereafter, the water contained in the cork friction material is evaporated under heating and vacuum conditions to create voids in the areas occupied by water, and oil is substituted and impregnated into the voids.

In this replacement, the vacuum process achieves the function of boiling water at a low temperature and evaporating it in a short time, and the important function of forcibly impregnating it with oil. By heating the oil to 60°C to 100°C and immersing the cork friction material in the oil, it is possible to uniformly impregnate a large amount of oil to the inside in a shorter period of time, making it possible to impregnate a large amount of oil that was previously impossible. Cork friction material suitable for use in clutch facings, brake shoes, etc. that require
A cork friction material impregnated with oil at a weight ratio of 25 to 30% can be easily obtained.

In addition, the amount of oil impregnated is suitably 15 to 50% by weight depending on the purpose and application of the cork friction material, and the optimal weight ratio is 25 to 30%, but according to the present invention, the amount of water mixed in, This value can be easily obtained by controlling the amount of water to be evaporated.

As for the adhesive, since water does not have a large effect on the adhesive strength, any conventionally used adhesive that can adhere to cork grains will suffice, and there is no need to limit the adhesive in particular.

〔Example〕

Next, the present invention will be explained with reference to Examples.

Use cork particles with a size of about 20 to 70 mesh, add water and adhesive at a 50% weight ratio, stir for 5 to 10 minutes, and put the desired amount into a mold. After heating and compressing the material, the material is taken out from the molding die to obtain a cork friction material having a desired shape.

At this time, the moisture existing between the cork particles secures a space in the cork friction material corresponding to the amount of water filled, and this is immersed in turbine oil #200 heated to 75°C to 85°C and heated to 40°C under 3 mmHg. After vacuum impregnation for a minute,
A cork friction material with an oil weight ratio of 41.5% by weight was obtained.

When carrying out the present invention, it is also possible to apply the cork friction material to the metal substrates of clutches, brakes, etc. in advance and then impregnate it with oil. This will increase the adhesive strength between the cork and the metal substrate. In addition, clutch facings and brake shoes with excellent friction characteristics can be easily obtained.

〔Effect of the invention〕

As described above, according to the present invention, due to the action of the impregnated oil replacing water, the friction characteristics can be significantly improved without impairing the friction coefficient, and the life of the cork friction material can be maintained for a long time. Moreover, because the oil distribution is almost uniform, cork friction material obtained by cutting from a block can also have the same effect, making it an excellent cork friction material that cannot be obtained with conventional methods. It is.

Claims (1)

[Claims] 1. In a cork friction material formed by integrally molding cork particles with an adhesive; cork particles, an adhesive, and water are mixed, and the mixture is fixed and molded integrally with an adhesive. A cork friction material characterized in that it is impregnated with oil by immersing it in heated oil and adding vacuum to evaporate water in the cork friction material and replacing the water 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.