JPS6234974B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention does not impair the friction coefficient of cork,
The present invention relates to a method for producing compressed cork plates for clutch facings and brake shoes that improves the friction characteristics and the wear resistance of cork friction plates. It is well known that cork is used as a friction plate, and is widely used in industrial sewing machine clutches, motor clutch facings, brake shoes, and the like. This takes advantage of the excellent wear coefficient of cork, which is a natural product. However, cork has low physical strength and is prone to wear.
Particularly when used with a half-clutch, etc., it caused abnormal wear and had the disadvantage of requiring replacement within a short period of time. In order to solve this problem, sheets of pressed cork were immersed in an oil bath, and the oil was attached to or partially penetrated into the cork to improve its wear resistance, but this method meant that the oil remained only on the surface, and the cork could not be used. When the inner surface wears out, the original cork material comes out, resulting in a significant drop in wear resistance. Further, since only a small amount of oil is deposited and penetrated, not only can no significant improvement in wear resistance be expected, but there are also many problems such as a long period of time required for impregnation. The present invention eliminates these drawbacks and improves the wear characteristics without impairing the friction coefficient of cork.
The purpose is to greatly extend the life of cork friction plates. In the present invention, cork particles crushed to an appropriate particle size are mixed and stirred with vegetable oil or mineral oil, etc., so that the oil is attached and impregnated to the cork particles, and then an appropriate amount of adhesive is further mixed and stirred. Thereafter, the cork grains are placed in a mold having a desired shape, and the cork particles are pressed and heated for a certain period of time to harden the adhesive, and after cooling, the cork grains are taken out from the mold to obtain the desired pressed cork block.
This is a manufacturing method for obtaining pressed cork plates for clutch facings and brake shoes by using this material as it is or by pressurizing it into a desired shape. The pressed cork plate for clutch facings and brake shoes thus obtained is a material with excellent wear resistance in which the cork grains are impregnated with oil and the gaps between the cork grains contain oil. In addition, after mixing and stirring the oil-applied and impregnated cork grains and adhesive, this is placed in a mold together with the metal substrate of the clutch facing and brake shoe, and the adhesive is hardened and pressed. By integrally molding the cork plate and the metal substrate, the process can be greatly shortened and an excellent molded product with strong adhesion can be obtained. Next, examples will be shown. Example Cork particles: 20-80 mesh Adhesive: Phenol adhesive Softener: Glycol oil Turbine oil #200 After putting the above 20-80 mesh cork particles into a ribbon blender, gradually add turbine oil. , 5 minutes to 10 minutes after adding the entire required amount of turbine oil.
Stir for a minute. Thereafter, a phenolic adhesive containing a softening agent conventionally used to increase the flexibility of cork is further added, and stirring is continued for 5 to 10 minutes. At this time, the softener and adhesive may be added separately. A desired amount of the cork grains obtained in this way is put into a mold, compressed, heated by a normal heating method (oven heating, high frequency heating, steam heating, etc.), the adhesive is cured, and after cooling, the mold is Release from the mold to obtain a pressed cork block. In this case, if a room temperature curing type adhesive is used, the heating process can be omitted, but in order to obtain sufficient strength, it is better to use a heating method using a thermosetting adhesive. ing. The weight ratios of cork particles, turbine oil, adhesive, and softener were as shown in Table 1.

[Table] In addition, the bulk specific gravity of the pressed cork blocks obtained by the above method is 0.53 g/cm ³ without the addition of turbine oil.
In the case of adding oil, the weight was increased to correspond to the amount of oil added, and the amount of cork per volume was kept constant, and the relationship between the amount of oil added and physical properties was investigated. (1) Tensile strength As a cork sheet with a thickness of 5.0 mm, this
It was cut into 12 mm pieces and the shrinkage strength was measured using a Schottspur type tensile tester. The test results are shown in Table 2, and although a slight decrease in tensile force was observed due to the addition of oil, the strength as a friction plate was sufficiently maintained.

[Table] (2) Coefficient of friction As shown in Table 3, the coefficient of friction decreases slightly with the addition of oil, but this does not impair the properties of the friction plate.

[Table] (3) Amount of friction The amount of wear decreases with the amount of oil added.
At ~65PHR, the amount of wear remains almost the same, but the amount of wear is one-third to one-fourth of that without oil, and the effect of oil addition is significantly large.

[Table] Test method: Measured using a Williams abrasion tester, and the amount of wear was calculated assuming that the amount of wear without oil was 1. In addition, even when measuring oil addition amount of 65 or more (friction coefficient, wear amount, tensile strength), the values show almost the same value as 65PHR. This means that even if more than 65 PHR of oil is added, during compression molding, if the weight ratio of oil to cork grains is more than 50%, it will not remain in the cork grains and between the cork grains and will flow out. Therefore, adding more than 65 PHR of oil will be meaningless. Therefore, the weight ratio of oil to cork grains of 50% by weight is the limit that can actually be used, and there is no need to add more oil than this.
Therefore, the practical range of the present invention is that the weight ratio of oil to cork particles is 5 to 50% by weight, as shown in the above tests. As described above, according to the present invention, it is possible to impregnate a pressed cork board with a desired amount of oil, and to impregnate the pressed cork board in a larger amount than in the conventional method, and by the action of the oil impregnated into the cork grains or existing in the spaces between the cork grains. , it is possible to improve the friction characteristics and greatly extend the life of the friction plate without impairing the friction coefficient. In addition, the compressed cork plate of the present invention has a great feature that the oil distribution is uniform, so even if it is processed from a block, cut, etc. or the friction plates are worn, the effect will not change.This is an excellent point that cannot be obtained with conventional methods. It is. Furthermore, as shown in Table 5, the oil-added pressed cork block and the additive-free pressed cork block of the present invention were used as #90.
When immersed in turbine oil and checking its weight change over time, it was found that the oil-added pressed cork block absorbed significantly more oil than the unadded pressed cork block. For impregnating purposes, the oil addition block of the present invention is effective.

【table】

Claims (1)

[Claims] 1. Cork particles crushed to an appropriate particle size and oil such as vegetable oil or mineral oil are mixed and stirred to adhere and impregnate the cork particles with oil, and then an adhesive is further mixed and stirred. After that, the pressed cork plate for clutch facings and brake shoes is manufactured by placing the cork plate in a mold having a desired shape, applying pressure to harden the adhesive, and molding the cork particles into a fixed and integral piece. 2. After stirring and mixing the cork particles that have been previously coated and impregnated with oil and the adhesive, the cork particles are placed in a mold together with the clutch facing and the metal substrate of the brake shoe, and the adhesive is bonded by applying pressure. A method for manufacturing pressed cork plates for clutch facings and brake shoes, which is formed by curing a cork agent and integrally molding cork particles onto a metal substrate.