JPS594461B2 - Friction material with excellent wear resistance, cold resistance, and snow resistance - Google Patents

Description

[Detailed Description of the Invention] This invention provides a
This invention relates to friction materials used as brake shoes for trains such as railway vehicles.

Friction materials for brake shoes are generally required to have the following properties.

(1) The shortest braking distance with excellent friction characteristics can be ensured.

That is, it has heat resistance and does not fade even when braking at high speeds, and it also has cold and snow resistance and does not become non-braking even when braking in snow at low temperatures. In other words, the friction characteristics are stable. (2) Good wear resistance;
It is economical because it can be used for a long time and the manufacturing cost is low.

(3) Less aggressiveness towards the other material, the wheel.

In other words, it may damage the wheels, increase electrical resistance,
Must not be prone to slipping. (4) Mechanical strength is sufficient.

Io (5) When used as a brake shoe, it should be light in weight and easy to replace.

(6) No sparks are generated during braking, and there is no problem with vehicle operation.

(7) Generates so-called pollution such as noise and odor when braking15
What not to do.

However, conventionally, brake shoes using various friction materials,
For example, brake shoes for railway vehicles can be roughly divided into the following four types.

That is, (a) cast iron brake shoes, (alloy cast iron brake shoes, ←
→Sintered alloy brake shoes and intermediate composite brake shoes are available. However, although these conventional brake shoes using friction materials have any of the seven advantages listed above, they also have the following drawbacks.

In other words, cast iron brake shoes (a) and alloy cast iron brake shoes (25) have poor friction characteristics and wear resistance due to their material characteristics, are heavy, generate sparks, and cause pollution. In addition, Ino's sintered alloy brake shoes have hygienic problems such as worker poisoning due to the organic solvent contained in the caking material, as well as a high risk of fire due to the flammability of the solvent. Workability is poor. Furthermore, the synthetic brake shoe of O is
It causes aggressiveness to other materials, mechanical strength, and pollution such as noise. In addition, dust pollution is generated during the work process, and when caking materials are used, there are hygienic problems such as workers becoming poisoned by the organic solvents contained in the caking materials. Due to its flammability, it poses a high risk of fire and makes work extremely difficult. Furthermore, since it contains a solvent and a hardening agent, it causes inconveniences such as gas cracking during molding, resulting in poor workability. This invention eliminates the drawbacks of conventional brake shoes made of friction materials, and has the advantages of synthetic brake shoes, such as good friction characteristics, high wear resistance, and no spark generation. It has good snow resistance and non-aggressiveness to mating materials, which are the advantages of bonded brake shoes, and solvent-free liquid phenolic resin (product name, e.g. Kashiyuichi Co., Ltd.) has a good effect on workability, especially in the work process. (hereinafter the same applies) and is fired at a predetermined pressure and temperature.

First, in the friction material of the present invention, copper is an effective additive for increasing the coefficient of friction, but if it exceeds 20%, it is unsuitable because it lowers the hardness of the friction material and significantly accelerates wear.

However, if it is less than 1%, it is not possible to obtain the necessary coefficient of friction, and copper of 1 (:fl) or more is necessary. Tungsten is an effective additive in that it increases hardness and contributes to wear resistance, but in the case of the friction material of this invention, addition of more than 10% will increase the hardness enough to damage the mating material, which is the object to be rubbed. Therefore, it cannot be used for any purpose.

However, if it is less than 5%, the hardness as a friction material is too low and it accelerates wear, so 5% is the minimum required amount. Cobalt has a large influence on toughness.

However, if it is less than 4%, the toughness cannot be improved and brittleness remains, and as the amount added increases, the effect of improving the toughness of the friction material increases, but 7C! ), a plateauing phenomenon will occur where the effect cannot be expected to be proportional to the amount added, so in consideration of the balance between effectiveness and economy, the maximum is 7 (up to F6).Graphite provides lubricity and prevents seizure. However, if it exceeds 30%, it is unsuitable because it lowers the coefficient of friction and causes slippage, and if it is less than 3%, it has poor lubricity and may cause seizure or have poor resistance. Since abrasion properties are also poor, the friction material of the present invention requires a maximum of 30% graphite and a minimum of 3% graphite.

Red lead or silica, or mixtures of red lead and silica, are effective additives to increase the stability of the coefficient of friction, but 5
If it is less than 15%, this effect will be small, and if it exceeds 15%, it will damage the mating material by scratching when used as a friction material, so the additive of this invention should be at least 5I:! ) is required, up to a maximum of 1501).

Asbestos or rock wool, or a mixture of asbestos and rock wool, has a large effect on improving pressurizing properties and mechanical strength, but if it is less than 3%, it will lack mechanical strength, and 10 (
Addition of more than fl) causes deterioration of the pressurizing characteristics, and the so-called "tightness" disappears.

Next, a method for manufacturing a friction material according to the present invention will be explained. First, copper 1-20%, tungsten 5-10% by weight.
%, cobalt 4-701), graphite 3-30%, red lead, one or two types of silica 5-15%, asbestos, one or two types of rock wool 3-10%, iron 30-70%
% of each powder are mixed.

In addition, this iron content includes sponge iron powder, cast iron powder, and phosphorous iron.
A species or a mixture of two or more species may be used. Next, 5 to 30% of a solvent-free liquid phenolic resin, which does not contain a solvent, is gradually mixed into 70 to 95% of the mixture of the above-mentioned materials as a binder to form a viscous mixture.

In this way, when a binder is added, unlike when only the powder of each material is mixed, each material once uniformly kneaded is completely and uniformly dispersed, becomes a viscous kneaded material, and is separated and diffused again. Never. The use of a binder prevents dust from scattering, and the solvent-free liquid phenolic resin does not contain any solvent, so there is no risk of alcohol poisoning for workers, and it is not flammable. Work can be done safely and hygienically without the risk of fire. Next, the mixture was packed into a mold to be molded as a friction material for brake shoes etc.
Heating at 50℃, 150-250Kf/CdllO-25
Molded by pressurizing operation for 8 to 16 minutes at 150 to 250℃.
After several hours of heat treatment, the brake shoe, which is a friction material, is completed. Next, Table 1 lists examples of brake shoes made of two types of friction materials having high friction coefficients and low friction coefficients having the composition of the present invention, and at the same time, examples of brake shoes made of conventional friction materials that do not belong to the composition of the present invention. The brake shoe is listed for comparison, and the test using a full-scale brake tester and other performance test conditions and results are described below.

In addition, friction materials 1 and 2 of Examples according to the present invention have the compositions listed in Table 1, are kneaded, packed into a mold to be used as brake shoes, heated at 160°C, and heated to 200°C. /Cfil
The material was molded by applying pressure for 20 minutes, and heat treated at 180°C for 14 hours to obtain brake shoes of friction materials 1 and 2.Furthermore, the friction material 1 of the present invention shown below can be used for new types of trains, etc. The friction material 2 of the present invention is a material with a high friction coefficient suitable for applications where the braking pressing force is relatively small, and the friction material 2 of the present invention is a material with a low friction coefficient suitable for applications where the pressing force is relatively large, such as old trains. An example is given in which each exhibits a good condition.

A friction and wear characteristic test using a full-scale brake testing machine was conducted under the following conditions.

That is, the moment of inertia is 120 Kf-m-Se (2
In other words, the equivalent inertial weight of the current vehicle is equivalent to 50.8 tons. Braking is performed 24 times in a dry state at room temperature, and the initial speed (Km/h) in each case is 65-35-95-125E.
-65-125-35E-95-95-125E-35
-125-95E-65-65-125E95-125
-125-65E-35-35-125E-65, and the pressing force of the brake shoe against the wheel is 1 in regular use.
．． 5t0n (the above initial speed is unmarked), and in the case of an emergency ("E" attached to the above initial speed number), it was 3.5t0n, and in both cases, one push was performed. Also, the friction area is 2.52×
The length of the test was 104 m, and the wheel temperature at the start of the test was approximately 60°C. The test results are shown in Table 2. In addition, contrary to the normal temperature drying test mentioned above, a low-temperature water sprinkling test was conducted to find out the changes in the braking effect due to the water film during snowfall and stormy weather, and the conditions were as follows. be.

That is, when braking is repeated 20 times in succession at low speed, each initial speed is 35 KmA, and water at a temperature of 0°C is applied for 1000 strokes/
Water was sprinkled on the brake sliding surface, and the pressing force of the brake shoe against the wheel was 1.5t0n, which is the usual one, and the friction area was 2.5.
2 x 10J, and the wheel temperature at the start of each of the 20 tests is -
The temperature was 3°C, and the atmospheric temperature for the braking test was -5°C. The experimental results of this watering test are shown in Table 3. As explained above, the present invention provides the following significant effects as a friction material for brake shoes.

(1) Since solvent-free liquid phenolic resin is used as the caking agent for the friction material, there is no scattering of dust when mixing the raw materials for the friction material, which prevents respiratory disorders for workers and is extremely hygienic. Furthermore, since it does not contain a solvent, it can prevent poisoning by solvents such as alcohol, and can also avoid the risk of fire.

In addition, since it does not contain a solvent or a hardening agent, it is possible to avoid problems such as gas cracking during molding into a brake shoe, resulting in good workability. (
2) As is clear from the test results when dry at room temperature in Table 2, the friction material 1 of the present invention, which has a high friction coefficient, has a higher average friction coefficient than the conventional friction material 1, which also has a high friction coefficient. Moreover, it is stable and has little wear, indicating that it is an excellent friction material.

Similarly, the friction material 2 of the present invention having a low friction coefficient is also better than the conventional friction material 2 having a low friction coefficient for old-model vehicles, and even more than the friction material 3 which is a cast iron brake shoe shown for reference. It is also found that the friction coefficient is good and the amount of wear is small.
It is clear that it is an excellent friction material. (3) As is clear from Table 3, the average friction coefficient Fm in the low-temperature water spray test of brake shoes using the friction material according to the present invention is Fm = 0.37 for friction material 1 of the present invention; 2, f snoring is 0.19, and it only changes within the range of ±5% of the test result value (see Table 2) using the same friction material at room temperature. The brake shoe made of a friction material according to the present invention exhibits an excellent braking effect that is almost the same as when dry at room temperature, even when low-temperature moisture consisting of ice and snow water enters the brake sliding surface,
As shown in Table 5, the low-temperature water spray test results for conventional friction materials 1 and 2 show that the entry of ice and snow water does not result in a non-braking state (4) The high performance of the present invention as shown in Table 4 Friction and each friction material with a low coefficient of friction are
It also has better mechanical properties than conventional friction materials.

That is, the friction material according to the present invention has a large friction coefficient,
It has excellent wear resistance and high mechanical strength, so it maintains its strength as a friction material even at low temperatures, and the friction coefficient does not decrease even in the presence of ice and snow, making it suitable for braking in snow. .

Claims (1)

[Claims] 1% by weight, copper 1-20%, tungsten 5-10%
, 4-7% cobalt, 3-30% graphite, 5-15% one or two of red lead and silica, 3-10% one or two of asbestos and rock wool, 30-70% iron. Add 5 to 30% of a solvent-free liquid phenolic resin as a binder to 70 to 95% of a mixture consisting of
cm^2, a homogeneous kneaded material formed by pressurizing operation for 10 to 25 minutes at a temperature of 80 to 250 °C is 8 to 1
A friction material with excellent wear resistance, cold resistance, and snow resistance that has been heat treated for 6 hours.