JPH0120197B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake shoe used in dehydrators, etc., and its purpose is to provide the necessary coefficient of friction (braking force) and wear resistance that can withstand long-term use. At the same time, when braking high inertia force, the wear coefficient of the brake shoe is too high, which causes the stick slip phenomenon and generates so-called squealing noise when stopping, but we have developed a brake shoe that can prevent this. That's what you're trying to get.

Conventionally, the brake shoe for a dehydrator of a washing machine that washes 2.8Kg or 3.2Kg of cloth when dry has a large inertia, so a brake shoe for a dehydrator with a small inertia such as a 2.0Kg or 2.2Kg washing machine has been used.・With glass fiber-containing polyamide resin (6.6-nylon), during braking, the brake shoe becomes hot due to frictional heat, and the coefficient of friction increases rapidly, causing a so-called squealing noise and abrasion powder of the glass fibers, causing the brake shoe to become hot. As shown in Figure 1, the sliding side is impregnated with phenol resin and hot press molded asbestos 1, and the side that fits with the lever is made of nylon molded product 2, which is glued together. Was. In addition, the sliding side of Asbestos 1 was sandblasted on both sides to remove the phenol layer exposed on the surface in order to obtain the necessary friction coefficient and to create unevenness while removing the phenol layer on the adhesive surface to obtain adhesive strength. was. This results in a very expensive brake shoe. Moreover, it was difficult to control the quality of the bonding process. Based on the above, there was a desire to develop a brake shoe that uses a thermoplastic resin with a small inertial force and a simple assembly process, similar to that used in washing machines.

The present invention meets these demands and will be described below with reference to FIGS. 2 to 5.

In the dehydrator shown in FIG. 2, when washed clothes are placed in the dehydration basket 3 and the dehydration lid 4 is closed, the wire 5 is pulled and the brake shoe 6 is separated from the surface of the brake wheel 7. At the same time, the dehydration motor 8 is energized, and the dehydration basket 3 runs at speeds of 1,700 to 1000 per minute.
Since the rotation is 1800 times, the water in the clothes is scattered outside due to centrifugal force, runs down the wall of the dehydration tank 9, and drains into the drain port 1.
0 to the outside of the machine using a drainage hose (not shown). When dewatering is completed and the dehydrating lid 4 is opened, the wire 5 is loosened and the spring 1 shown in Fig. 3 is released.
1 pulls the brake lever 12, and the brake shoe 6 is caught in the brake wheel 7 (engulfing brake), and the brake is applied to stop the dewatering basket 3. The brake shoe 6 used in this way is
Polyamide resin (6.6-nylon) 50-70%,
It is molded by uniformly mixing and dispersing 5% to 15% of modified ultra-high molecular polyethylene, 1.5% to 3.5% of carbon fiber, and 20% to 50% of synthetic rubber (thermoplastic elastomer). An example of a preferred blending ratio is 58.5% polyamide resin, 6.5% ultra high molecular weight polyethylene, 3% carbon fiber, and 32% synthetic rubber.

As shown in the experimental data in Figure 4, the abrasion resistance of the brake shoe 6 is as follows: Enter 6,
6-nylon), the brake shoes of the examples exhibit wear resistance that is 6 times or more. This is because carbon fiber has lubricating properties,
This is because the worn glass powder becomes abrasive powder and increases the wear of the glass fiber. Furthermore, as shown in Figure 5, the friction coefficient (braking torque) of the brake shoe of a dehydrator with small inertia increases rapidly just before the dehydrator stops, reaching its maximum value. As a result, the wear powder from the brake shoe adheres unevenly to the sliding surface of the brake wheel, causing local changes in the friction condition.
In contrast, the brake shoe of the example is made of a crystalline resin (for example, ultra-high molecular weight polyethylene) that has a low melting point and is inherently excellent in wear resistance. As it softens, it adheres to the sliding surface of the brake wheel and acts as a lubricant, so there is no sudden increase in the coefficient of friction and the maximum value of the coefficient of friction decreases, so there is no stick slip phenomenon and no squealing noise. Does not occur.

In addition, compared to conventional asbestos adhesive brake shoes for dehydrators that have a large inertia force, this brake shoe is low cost, stable in quality, and non-polluting.

In addition, in this example, the case where 6.6-nylon was used as the polyamide resin was explained, but other polyamide resins such as 6.6-nylon were used.
-Nylon, 12-nylon, etc. may be used. Also, although the case where ultra high molecular weight polyethylene was used as the crystalline resin with a low melting point was explained, even if other HDPE is used, the same results as in this example will be obtained. It goes without saying that this effect can be obtained. in short,
The structure may be mainly composed of a mixture of thermoplastic crystalline resins having different melting points, such as a combination of polyamide resin and ultra-high molecular weight polyethylene (or HDPE).

As described above, according to the present invention, a mixture of thermoplastic crystalline resins with different melting points is the main component, synthetic rubber (thermoplastic elastomer) is mixed to reinforce the friction coefficient, and carbon fiber is added to reinforce the wear resistance. Since it is added to form the brake shoe, the coefficient of friction can be adjusted by adjusting the blending ratio of synthetic rubber, and the abrasion resistance is excellent due to the lubricity of carbon fiber. Furthermore, since home appliances are used indoors, if the equipment generates abnormal noise, it would mean that the equipment cannot be put to practical use.However, since the main component resin is a two-component system with different melting points,
When the temperature of the main component resin on the sliding surface rises to the glass transition point due to frictional heat during braking, the coefficient of friction increases rapidly, causing stick slip. It exhibits lubricity and prevents the coefficient of friction from increasing, which prevents squealing just before stopping. Furthermore, since it is a thermoplastic resin, it can be easily molded, completely solving the problems of the prior art. Crystalline resins are resins such as polyamide, polyethylene, polypropylene, and polyacetal that have a clear melting point. Furthermore, although the present invention has been described with respect to the brake shoe of a dehydrator, it goes without saying that the present invention is not limited to this and can be used to brake other rotating bodies.

[Brief explanation of drawings]

Figure 1 is a perspective view of the conventional brake shoe part.
Fig. 2 is a sectional view of a dehydrator using a brake shoe showing an embodiment of the present invention, Fig. 3 is a perspective view of the same brake mechanism, and Figs. 4 and 5 show the present invention and a conventional example, respectively. FIG. 6... Brake shoe, 7... Brake drum.

Claims (1)

[Claims] 1 Polyethylene resin that softens and acts as a lubricant 5~
The main component is a mixture of 15% by weight and 50 to 70% by weight of a thermoplastic crystalline resin with a higher melting point than the polyethylene resin, and 20 to 50% by weight of synthetic rubber and 1.5 to 3.5% by weight of carbon fiber are mixed with this. Brake shoe molded by