JPH0233893B2 - DENDOMISHINNOSEIDOSOCHI - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a braking device for an electric sewing machine using a cork friction material. The friction material used in the motor braking device of an electric sewing machine or the clutch facing of the power transmission device used therein must have an appropriate friction coefficient, and must be free from noise during operation or odor from the friction surface. Cork is prized because it causes very little occurrence.
However, it had poor wear resistance and had problems in terms of life. Therefore, in order to measure wear resistance, cork friction materials in which cork is impregnated with lubricating oil have been provided, as seen in Japanese Patent Publication No. 37-15059 and Japanese Patent Application Laid-Open No. 54-41312. In addition, some friction materials have been put into practical use in which cork is impregnated with such lubricating oil and solid lubricant particles such as molybdenum disulfide are dispersed on the surface using the same lubricating oil. However, in either case, the lifespan is still not sufficient, and improvements are desired. An object of the present invention is to provide a braking device for an electric sewing machine that has a long life. The present invention includes: a brake armature connected to a sewing machine drive shaft; a brake disc provided so as to be able to come into contact with and separate from the armature through a cork friction material;
In a braking device for an electric sewing machine having the brake disc and a magnetic circuit for magnetically connecting and separating the armature, the cork friction material is a liquid or semi-solid lubricant applied to the cork molded body and its friction surface. The liquid lubricant contained inside the cork molded body is a liquid or semi-solid lubrication agent applied to the friction surface of the cork molded body. It is a liquid lubricant that has a lower affinity for cork than the base oil of the lubricant layer. In the present invention, affinity refers to the strength of adhesion of the base oil of the lubricant to cork. The strength of adhesion is expressed by the contact angle (wettability) between the cork and the liquid or base oil of the surface lubricant. A base oil with good wettability means that it has good impregnating properties (easiness of the base oil to enter) into a cork molded body. Next, the present invention will be explained with reference to the drawings. FIG. 1 shows a cross-sectional view of the main parts of a power control device which is an example of application of the friction material of the present invention, and is a cross-sectional view of a motor equipped with a clutch and a brake. A flywheel 3 to which a clutch disk 2, which is one of the clutch components, is fixed is fixed to one end of a rotor 1 of a drive motor. The pulley end bracket 4 holds a clutch electromagnetic frame 5 having a clutch coil, a brake electromagnetic frame 6 having a brake coil, and a brake disc 7. Also, a pulley 9 that takes out the output via a bearing 8
and a sliding shaft 10 (spline shaft, etc.) at the other end.
It supports an output shaft 11 having a diameter. A clutch armature 14 and a brake armature 15, each holding a clutch lining 12 and a brake lining 13, are movable in the axial direction on the sliding shaft 10 and are held so as not to make any relative movement in the rotational direction, and are held together by a coupling 16. connected. In operation, the rotor 1 of the motor constantly rotates, and the flywheel 3 fixed to the other end stores rotational energy. When the clutch coil 17 is energized, the clutch side magnetic circuit 18 is generated, and the clutch armature is 14 is attracted to the clutch disk 2, and the rotational power is taken out through the clutch lining 12, the sliding shaft 10, the output shaft 11 (ie, the sewing machine drive shaft), and the pulley 9, and becomes a driving force. On the other hand, when stopping, the brake coil 19
By energizing, the brake side magnetic circuit 20 is generated, the brake armature 15 is attracted to the brake disc 7, and the brake armature 15 is attracted to the pulley side end bracket 4 through the sliding shaft 10 and the output shaft 11 via the brake lining 13 and the brake armature 15. The pulley 9 is stopped by the braking force generated by friction with the fixed brake disc 7. The present invention is an apparatus of this type in which a clutch lining 12 or a brake lining 13, that is, a friction material mainly made of the above-mentioned cork, is used. The reason why the life of the above-mentioned cork friction material in the present invention is improved is as follows. That is, the life of the cork friction material is due to the synergistic effect of the internal liquid lubricant and the surface lubricant. The internal liquid lubricant contained in the cork friction material gradually leaches (replenishes) the surface lubricant layer applied to the surface of the cork friction material during use, and functions to maintain the lubricity of the cork surface. The amount of reinforcement to the surface lubricant layer varies depending on the affinity of the internal liquid lubricant contained in the cork friction material for cork. If the internal liquid lubricant has a greater affinity for cork than the base oil of the surface lubricant, excessive leaching of the internal lubricant will result, forming a thick oil film layer under the surface lubricant layer applied to the cork friction surface. This results in the surface lubricant layer disappearing from the friction surface. However, by applying a base oil that has a higher affinity for cork than the internal liquid lubricant contained in cork, the surface lubricant enters the cork's uneven parts and is retained for a long period of time. This is because excessive leakage of the internal liquid lubricant contained in the internal liquid lubricant layer is prevented, and appropriate replenishment into the internal liquid lubricant layer is performed. In the present invention, the base oils of the internal liquid lubricant and the surface lubricant may be combined if they have different affinities for cork. The affinity for cork for examples of hydrocarbon oils is shown below in descending order of affinity. Incidentally, the affinity for cork is expressed by the impregnating property with respect to the cork molded body. Impregnated cork molded body of specified shape at 100℃
After immersing the cork in oil for a certain period of time, the oil adhering to the cork surface was removed and the amount of oil impregnated inside the cork molding was determined. The oil with a large amount of impregnated oil has a large affinity for cork. Polyalkylene glycol oil>Polybutene oil>
Fluorine oil>Neopentyl polyol ester oil>
Silicate ester oil>Diester oil>Phosphate ester oil>Alkylbenzene oil>Mineral oil>Polyphenyl ether oil>Polyolefin oil. Among these, combinations having different affinity for cork can be arbitrarily selected. Particularly preferred as surface lubricants are viscous lubricants such as graphite, molybdenum disulfide, tungsten disulfide, boron nitride, organomolybdenum, graphite fluoride, metal oxides and bentonites, silica gel,
It is a semi-solid grease made by blending dyes (copper phthalocyanine, indathrene), solid lubricants such as polyurea, and thickeners with base oil.
Furthermore, as the base oil for the internal liquid lubricant, the larger the difference in affinity for cork from the base oil for the surface lubricant, the more preferable it is in order to improve the life of the cork friction material. The viscosity of this internal liquid lubricant is 210°F.
(98.9°C) and a range of 3 to 80 mm ² /S is used. In view of the durability and braking performance of the cork friction material, a cork friction material having a diameter of 3.5 to 80 mm ² /S is particularly preferable. Antioxidants, such as amine compounds, phenolic compounds, or sulfur compounds, and rust inhibitors, such as carboxylates and sulfonates, are added to at least one of the surface lubricant and the internal liquid lubricant, as necessary. be able to. The cork molded body as used in the present invention is one formed by molding chips or powdered cork into a predetermined shape using an adhesive. The internal liquid lubricant can be contained inside the cork molded product by adding the liquid lubricant to the mixture of cork and adhesive before molding, or by adding the liquid lubricant to the mixture of cork and adhesive before molding, or by adding the liquid lubricant to the mixture of cork and adhesive before molding, or by adding it to the mixture under normal pressure or reduced pressure after molding. A method of impregnating at the bottom can also be adopted. The cork friction material referred to in the present invention can be used in addition to brake devices and clutch devices as shown in the above-mentioned drawings.
It can be used as a pitting prevention device for railroad car bogies as described in Japanese Patent No. 55-156763, a dehydration tank of a dehydrating washing machine, or a disc part used in a disc brake of a machine tool, etc. Next, examples of the present invention will be shown. In addition, the amount of solid lubricant added (volume %) in each of the following examples is a value based on the total volume of the composition. Example 1 Cork grains having a particle size within the range of 300-500 μm
85 parts by weight, 15 parts by weight of phenolic adhesive, 5 parts by weight of glycol (softener) and a viscosity of 2.4 to 101.0 mm ² /S (average molecular weight) at 210°F (98.8°C).
Polyolefin oil (antioxidant:
Nickel dibutyldithiocarbamate 0.5% by weight
After uniformly mixing 26 parts by weight of the mixture, the mixture was placed in a mold and compressed under pressure (10 kg/cm ² ), and heated and molded at a temperature of 130° C. for about 2 hours to obtain a cork board with a thickness of 10 mm.
A cork piece measuring 14 x 14 mm and 5 mm thick was cut from this cork board, and a ring-shaped cork molded product with an inner diameter of 68 mm, an outer diameter of 96 mm, and a thickness of 5 mm was made. 6% by volume of graphite and 54% by volume of molybdenum disulfide were mixed on the surface of this cork molded product. A semi-solid lubricant with polyalkylene glycol oil added as a base oil that has a higher affinity for cork than the internal liquid lubricant polyolefin oil is applied to this mixture, and a pin disc friction tester is used to test the durability and braking performance. The friction coefficient was evaluated under the following conditions. [Durability test] Sliding speed: 13m/s Surface pressure: 0.5Kgf/cm ² Disc surface temperature: 100℃ (metal plate temperature) Under the above conditions, the surface lubricant applied to the cork plate surface is consumed due to continuous sliding friction. The evaluation was based on the operating time. [Braking performance test] Sliding speed: 0.9m/s Surface pressure: 2.05Kgf/cm ² [Practical performance test] Typical usage conditions of an electric sewing machine were simulated, and the brakes were operated under deceleration, stopping, and constant slipping, as shown in the figure. Using the actual clutch/brake equipped motor shown above, the above operation was regarded as one cycle, and the evaluation was made based on the number of operation cycles until the surface lubricant applied to the cork surface was consumed. The measurement results are shown in Table 1. The lubricating oil viscosity in the table indicates the value of polyolefin oil. In addition, in order to clarify the advantages of the present invention, a comparison was made with what was conventionally used. Conventional cork friction materials use the same mineral as the base oil for the internal liquid lubricant and the surface lubricant. Therefore, the internal liquid lubricant (base oil) and the surface lubricant base oil have the same affinity for cork.

[Table] Table 1 shows that the cork friction material of the present invention impregnated with polyolefin oil, which has a lower affinity for cork than the base oil of the surface lubricant, is more than twice as durable as the conventional product using the same mineral oil. , practical performance 1.2
It can be seen that the improvement is more than twice as good. Example 2 A test piece cut out from a cork board molded under the conditions described above using the same particle size, softener, and adhesive as in Example 1 was coated with a polyolefin oil (average molecular weight: 300) having a low affinity for cork shown in Table 2. ~2100)
was impregnated with 20% by weight (based on the total weight including cork) under reduced pressure. Furthermore, a surface lubricant having the same composition as in Example 1 was applied to the cork test piece, and then tested under the same conditions as in Example 1. The results are shown in Table 2.

[Table] As shown in the table, it is clear that the cork molded body impregnated under reduced pressure had the same properties as Example 1, and was superior in terms of dynamic friction coefficient, durability performance, and practical performance. Example 3 A test with the same dimensions as in Example 1 was performed using a cork board obtained by molding using the same softener and adhesive as in Example 1 using cork grains having a particle size within the range of 1100 to 1200 μm. A piece was prepared and impregnated with 10% by weight (based on the total weight including cork) of the internal liquid lubricant shown in Table 3. As mentioned above, all internal liquid lubricants have a lower affinity for cork than the base oil of the surface lubricant. next,
The same surface lubricant having a high affinity for cork as in Example 1 was applied to the friction surface, and the friction coefficient and durability were evaluated using a pin disc friction tester. The results are shown in Table 3.

[Table] is shown below.
As shown in the table, it is clear that the cork friction material of the present invention is excellent in both the coefficient of dynamic friction and the durability performance. Example 4 A polyalkylene glycol oil (antioxidant: nickel dibutyldithiocarbamate) having the highest affinity for cork agents containing 5% by weight of the thickening agent shown in Table 4 was applied to the surface of the same cork test piece as in Example 1. 6% by volume of graphite and 54% by volume of molybdenum disulfide were added to a grease composition consisting of 0.5% by weight (mixed with 0.5% by weight), and the resulting surface lubricant was uniformly dispersed with a roll machine to a surface lubricant with a viscosity of 20.6%. ^mm2 /
It was applied to the friction surface of cork containing 10% by weight of S (210°F) polyolefin oil (low affinity for cork), and the dynamic friction coefficient and durability were measured using a pin disc friction tester under the same conditions as in Example 1. The practical performance of the motor with clutch and brake for an electric sewing machine shown in Figure 1 was evaluated. The results are shown in Table 4.

[Table] As is clear from Table 4, the durability and practical performance of greases using any thickening agent are significantly superior to those of the conventional products shown in Table 1. I understand.

[Brief explanation of drawings]

The figure is a sectional view of the main parts of the braking device for the electric sewing machine according to the present invention. 1...Rotor, 2...Clutch disc, 3...
...Ply wheel, 4...Pulley side end bracket, 5...Clutch electromagnetic frame, 6...Brake electromagnetic frame, 7...Brake disc, 8...Bearing, 9...Pulley, 10...Sliding shaft (Spline shaft), 11... Output shaft, 12... Clutch lining, 13... Brake lining, 14...
Clutch armature, 15... Brake armature, 16... Coupling, 17... Clutch coil, 18... Clutch side magnetic circuit, 19... Brake coil, 20... Brake side magnetic circuit.

Claims (1)

[Claims] 1. A brake armature connected to a sewing machine drive shaft, a brake disc provided so as to be able to come into contact with and separate from the armature via a cork friction material, and a brake armature that magnetically connects and separates the brake armature from the armature through a cork friction material. In the braking device for an electric sewing machine, the cork friction material includes a cork molded body, a liquid or semi-solid lubricant layer applied to the friction surface of the cork body, and a layer of lubricant applied to the inside from the friction surface. The liquid lubricant contained inside the cork molded body has a smaller affinity for cork than the base oil of the liquid or semi-solid lubricant layer applied to the friction surface of the cork molded body. A braking device for an electric sewing machine characterized by a liquid lubricant. 2. The liquid or semi-solid lubricant layer applied to the friction surface of the cork molded body is a grease consisting of a base oil, a solid lubricant, and a thickening agent, and the liquid lubricant contained inside the cork molded body and the above-mentioned A braking device for an electric sewing machine according to claim 1, wherein the base oil is a hydrocarbon oil.