JPS5919732A - Friction member - Google Patents

Abstract

PURPOSE:To put into the friction member an oily agent oozing out therefrom as a result of a clutch-brake operation, after the elasticity of the friction member is recovered, by a method wherein a powdered organic fiber material is interposed among cork particles from which the friction member is made. CONSTITUTION:For the cork particles, it is proper to use dried cork pulverized to 6-60 meshes and a cork particle bond which is nothing different from the bond used for producing the general compressed cork. Further, for the organic fiber material, it is most preferable to use powdered cellulose obtained from pulp because it has an excellent affinity for the cork particles and is similar in nature to the cork particles in respect of chemical and thermal stabilities. In addition, the powdered cellulose has such properties that it is not swelled at all with any of hydrophobic substances like oils and fats and absorbs the oily agent quickly. The above-mentioned materials are mixed together and after the mixture is heated and compressed, the oily agent is coated on the surface of the fiber material to thereby form a lubricating film thereon and at the same time, the mixture is caused to absorb the oily agent.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a friction material used for clutch linings and brake linings of electromagnetic clutches and brakes in industrial sewing machines. The structure of an electromagnetic clutch and a brake motor using a friction material will be explained with reference to FIG.

Figure 1 shows the configuration of the main parts of the electromagnetic clutch/brake motor. A flywheel 3, which is an inertial body, is fixed to one end of a rotating shaft 1 of a drive motor, and a clutch disk 2, which is one of the clutch components, is fixed thereto. The end bracket 4 located opposite the flywheel 3 has a clutch yoke 5 with a clutch winding 6a. Brake winding 6
The brake yoke 6 has a brake yoke 6, which holds a brake yoke, has a pulley 9 for taking out an output via a bearing 8 on one end, and supports a clutch shaft 11 having a sliding shaft (spline) 10 on the other end. There is. Clutch lining (friction material) 12. Clutch ring 14 holding brake lining (friction material) 13 Brake ring 16 is attached to sliding shaft 1
0 in the axial direction, but not relatively movable in the rotational direction, and both are connected by an O-ring 16 and a coupling 17.

Next, the operation of the electromagnetic clutch and brake will be explained.

The rotating shaft 1 is continuously rotating, and a flywheel 3 fixed to the end of the shaft is in a state where rotational energy is stored. Therefore, when the clutch winding arst is energized, the electromagnetic force 5b is generated, and the clasot ring 14 is attracted to the clutch disc 2, and the rotational power is transmitted through the clutch lining (friction material) 12, the sliding shaft 10, the clutch shaft 11, and the pulley 9. taken out. When stopping, brake winding 6
When power is applied to a, an electromagnetic force 6b is generated and the brake ring 15
is attracted to the brake lining, and is moved to the sliding shaft 10 through the brake lining (friction material) 13. A braking force is generated between the clutch shaft 11 and a pre-kinia fixed to the end bracket 4, and braking is performed.

Motors with electromagnetic clutches and brakes having the structure described above are widely used to drive industrial sewing machines that typically start and stop frequently. as 6.0
0 Used in Orpm-4.

Unfortunately, the squealing noises and unpleasant odors from friction surfaces during clutch and brake operation are disliked. Since the electromagnetic clutch/brake motor for driving the milling machine 5 performs clutch/brake operations approximately 10,000 times a day, a long-life friction material is required. To meet these demands, the friction materials used in motors with electromagnetic clutches and brakes include cork particles obtained by crushing dried cork bark with a soft cell structure, phenolic resin, polyurethane resin, urea resin, and vinyl acetate resin. Compressed cork, which is obtained by mixing with a particle binder such as and heating and compressing it, is used as the friction base material. Further, as known from U.S. Pat. No. 3,777,864, this friction base material is impregnated with an oil agent, such as grease or lubricating oil, to form a lubricant film on at least the friction surface of the friction base material. material is used. On the other hand, highly ground carbon steel is generally used as a mating material for these friction materials.

The reason why cork is used as the main component of the above-mentioned friction matrix, that is, pressed cork, is that although cork is a natural plant product, it is chemically resistant to oils, organic solvents, organic acids, 5-soap alkalis, and salts. This is because it is stable and has sufficient heat resistance as a friction base material for a motor with an electromagnetic clutch/brake. Furthermore, it is soft and has a large degree of elastic freedom based on the structural characteristics of approximately 260,000 fine air-filled cells per CrII, so it has advantages such as a soft hitting sound during clutch/brake operation.

On the other hand, if the pressed cork does not generally have a lubricating film on its friction surface, the friction coefficient tends to change due to external factors such as temperature and sliding speed, resulting in unstable clutch/brake operation.

Furthermore, since pressed cork itself has a high coefficient of friction, the coefficient of static friction is higher than the coefficient of dynamic friction, just like other materials. In other words, as is well known, the stick
Slip phenomenon is likely to occur, and noise is likely to occur during clutch/brake operation. Furthermore, since pressed cork has low heat dissipation properties, frictional heat easily accumulates, and as a result, the interparticle bonding force of pressed cork near the friction surface becomes smaller than the adhesion force with the other material, and cork particles This causes abnormal wear that transfers to the mating material or causes it to fall off. This phenomenon is especially seen when the lubricating film formed on the friction surface loses its function and clutch/brake operation is performed at high speed.
The coefficient of friction tends to change due to external factors such as temperature and sliding speed, accelerating wear and reaching the end of the life of the friction material.

In order to prevent the above-mentioned problems, conventionally, at least the friction surface of pressed cork was regularly coated and impregnated with oil, such as grease or lubricating oil, to make the lubricating film function and overcome the disadvantages of pressed cork. . So-called friction systems have been put into practical use that are designed to allow as much base oil as possible to penetrate between particles of pressed cork, etc., either directly in the case of lubricating oil or by utilizing its oil-releasing properties in the case of grease.

However, this type of friction material is extremely difficult to penetrate into the narrow gaps (grain boundaries) between the cork particles of pressed cork. The disadvantages were that the oil solution easily oozed out, was unstable over time, and could not withstand long-term use.

Purpose of the Invention The present invention solves the above-mentioned drawbacks, and makes it easier to form a lubricating film with an oil while taking advantage of the advantages of compressed corrugation, which is that it is soft and has a large degree of elasticity. Structure of the Invention The present invention utilizes the oil absorption properties of organic fibers interposed between cork particles to re-inject the oil that oozes out as the friction material is compressed during clutch/brake operation into the friction material when the friction material recovers its elasticity. It was designed to be quickly incorporated into the system. Its characteristics (conventional friction L made of cork particles and particle binder)
The purpose is to interpose a group of oil-absorbing organic fibers at least near the friction iM1:i between the cork particles of the pressed cork, which is the friction force. Furthermore, the inorganic fiber is powdered cellulose, and the oil agent that these organic fibers absorb is mineral oil.

An effective lubricating film formed on the friction surface of a friction material base with one or more active ingredients selected from the group consisting of α-olefin oligomers, polyethers, diesel esters, hinterate esters, and phosphate esters. It is a liquid substance of the same type as the ingredients. The cork particles used in the present invention are
It is made by drying and pulverizing cork bark, and the particle size is not particularly limited, but 6 to 60 mesh is suitable. If the particle size is small, a large amount of particle binder is required, and the workability when producing pressed cork by heat compression becomes poor. If the particle size is too large, the distribution of organic fibers, which is one of the characteristics of the present invention, will become localized, which is not preferable. The particle binder used in the present invention is no different from that in the case of general pressed cork, and for example, phenol resin, polyurethane resin, vinyl acetate IHI''a, etc. are used as appropriate.The organic fiber used in the present invention is: For example, polyamide fiber, polyvinyl alcohol fiber, polyvinylidene chloride fiber.

Polyvinyl chloride fiber, polyester fiber, polyacrylonitrile fiber, polyethylene fiber.

There are synthetic fibers such as polypropylene fibers, polyurethane fibers, and polyfluoroethylene fibers, vegetable fibers mainly composed of cellulose, and animal fibers mainly composed of protein. More than one species is used as appropriate. However, particularly preferred among the above organic fibers is powdered cellulose obtained from pulp. Powdered cellulose, which is in the form of fibers and has a soft cell structure, has excellent affinity with cork particles, and is chemically stable and thermally stable, as well as not producing off-flavors due to frictional heat. Exhibits properties similar to particles. In addition, cellulose has low hygroscopicity and does not swell at all when exposed to hydrophobic substances such as oils and fats, and it has the property of quickly absorbing oils directly or even if they are modified into grease or solo knobs. (Cork is used for waterproofing purposes and cork stoppers; it is generally extremely difficult to infiltrate liquid into cork particles due to cork's own resinous substance and uniform cell structure.)

The substance used to hydrophobically treat the organic fibers is mineral oil, α-
Olefin oligomer (poly α-olefin/), polyether (polyalkylene glycol, polyglycol,
Polyalkylene/Noxite).

A liquid hydrophobic substance consisting of one or more types selected from the group consisting of diester (dibasic H ester), hindered ester (HoIJ Alleste/L), and acid ester. However, it may also contain various additives that form an effective lubricating film on the friction surface of the friction base material. For example, high-grade alcohol.

Ketones, esters, amines or higher fatty acids; oily agents which are long chain compounds with polar groups such as metal soaps and oils; antifoaming agents such as polymethylsiloxane; sulfonates, amines, organic acids or their salts. , rust preventives that are organic compounds with polar groups such as esters, organic silicon compounds, water repellents such as higher aliphatic amines, adhesives such as polybutene, polymethacrylate-1'+ aluminum soaps of unsaturated fatty acids, and more. Free fatty acids, glycerides, alkaline earth salts and lithium salts of naphthenic acids, zinc soaps, anti-sealing agents such as petrolactam, coloring agents such as anthraquinone dyes, aromatic amines, and phenols.

Antioxidants such as zinc sialgyldithiophosphate compounds, diluents such as various organic solvents, molybdenum disulfide,
A solid lubricant such as graphite, lead oxide, or polytetrafluoroethylene powder, mixed with two cork particles, a binder, and an organic fiber;
After heating and compression, an oil agent can be applied to the surface of the organic fibers interposed between the cork particles to form a lubricating film and absorb the oil at the same time, or alternatively, the organic fibers can be treated with oil absorption in advance to adhere the particle binder. The friction material of the present invention can also be produced by further forming a lubricating film on the friction surface of a friction base material mixed with cork particles and heated and compressed.

In the present invention, the mixing ratio of the two-grain cork particle pre-consolidation agent and the organic fibers is related to the friction coefficient and life of the friction material to be manufactured, but is not particularly restricted as long as the hygroscopicity of the cork particles is taken into consideration. However, in the case of relatively easy-to-handle cork particles of about 6 to 60 mesh, cork particles of 10
It is appropriate to use 10 to 30 parts by weight of the particle binder and 2 to 50 parts by weight of the organic fiber to Q parts by weight. This is because if the amount of the particle binder is small, the mechanical strength will be insufficient, and if the amount is too large, the organic fibers interposed between the cork particles will be wetted, resulting in a decrease in oil absorption. If the amount of organic fibers is small, the lubricant film may not be sufficiently thick, or the lubricant that seeps out from the surface of the friction material due to compression of the friction particles due to repeated clutch/brake operations can be quickly regenerated when elastic recovery occurs. The oil absorption function is significantly reduced, and if the amount of organic fibers is large, the bonding between cork particles is hindered, resulting in a decrease in the mechanical strength of the friction base material. Incidentally, the above-mentioned friction material is the clutch lining 12. Brake lining 1
3 can be used with the same configuration.

Next, the present invention will be explained from the perspective of friction characteristics. However, the friction characteristics described below are based on JISD4411, the mating material is a disk made of carbon steel ground to a surface roughness of 3S, the sliding speed is 2 m/sec, and the surface pressure on the friction material is 1.8 wyf.
/cm.

FIG. 2 is a characteristic diagram showing the relationship between friction surface temperature and dynamic friction coefficient. In the figure, A is compressed cork particles with an apparent density of about 06 g/Qc obtained by heating and compressing cork particles of 14 to 35 mesh to EO'C using polyurethane resin as a particle binder.
The particle binder content is 20 wt%), and B has the same cork particles and binder as humans, so the apparent hardness is about 0.6! It is a fired cork that is heated and compressed at 170°C to give a ratio of 1.5 m/cc. C uses A as the friction base material and has a kinematic viscosity of 28 cst at 40°C.
A lubricating film is formed on the friction surface by impregnating 22 parts by weight of alkylbenzene. The friction material of the present invention is made by absorbing 30 parts by weight of the alkylbenzene used, mixing it, and heating and compressing it at 60°C.E is the same corrugated particles and particle binder 1
This is an example of the present invention in which the alkylbenzene used in C was formed on the friction surface of a friction piece obtained by adding 30 parts by weight of powdered cellulose to 0 parts by weight and heating and compressing it with EO'G. In Fig. 2, from the characteristic curves A and H, the compression corrugation,
When cork such as fired cork is used as a friction material, the rate of change in the coefficient of dynamic friction due to temperature is large.

The coefficient of dynamic friction is still high. In other words, it is clear that the friction material is likely to squeal during clutch/brake operation. In this case, even if, for example, a phenol resin or the like is used as a binder for the cork particles, or even if the particle diameter of the cork particles is changed, the characteristics of the dynamic friction coefficient with respect to the friction disc temperature tend to remain the same.

On the other hand, C corresponds to the friction material described in U.S. Pat. No. 3,777,864, in which cork is impregnated with oil or grease. By forming such a material, the rate of change in the coefficient of dynamic friction with respect to temperature is reduced compared to the case where cork is used as the material. However, in the characteristic curve of C, the coefficient of dynamic friction decreases as the temperature increases, reflecting the decrease in the viscosity of the alkylbenzene that forms the lubricating film, but when the temperature exceeds approximately 70"G, the coefficient of dynamic friction increases again. On the other hand, in the case of the present invention example and H, the characteristic curve is similar to that of C in a relatively low temperature range, but when the temperature exceeds approximately 70°C, the characteristic curve is clearly different from that of C. In other words, in the case of D and H, the coefficient of dynamic friction does not increase even if the friction plate temperature exceeds 70'G, reflecting the decrease in the viscosity of the alkylbenzene that forms the lubricating film on the friction surface. When I examined the friction surface of C's friction material after the measurement, I found that the lubricant film had already disappeared and it had become dry and cork-like. When cut, the internal cork particles were sufficiently wetted by the alkylbenzene that had penetrated between the particles.(Alkylbenzene occupies about 22 folds of friction material and is almost the same before and after measurement.) In contrast, in the example of the present invention, Aruri, E
was wetted by the alkylbenzene on the friction surface after measurement, and therefore continued to form a lubricating film. This means that even if the alkylbenzene that originally formed the friction surface is consumed by frictional heat, the alkylbenzene absorbed by the organic fibers interposed between the cork particles can easily come out to the friction surface due to capillary action, as in the present invention. This makes it impossible to maintain the function of the lubricating film.

As described above, it is clear that the present invention is an effective means for continuously maintaining the intended function of the lubricating film of a friction material and providing stable friction characteristics over a long period of time.

Description of examples Rejected, explained by example.

As the base material of the friction material, 6 (comparative example) 1, 5. ' (Example of the present invention) was used. However, 6. ．． 5. M is as mentioned aboveC
, D, and E, but the oil used was alkylbenzene (same as that used in C, D, and E) with a kinematic viscosity of 28 cst at 4o''C as a base oil, and polyisobutylene and stearin. Grease prepared with lithium oxide and molybdenum disulfide.

The three types of friction materials mentioned above were attached to a motor with an electromagnetic clutch and brake shown in Fig. 1, and the clutch and brake were operated 2QO times. After that, cool the motor with the electromagnetic clutch/brake to O'C, operate the clutch/brake, and check for any squealing noise. Additionally, the friction material was removed and the condition of the friction surface was observed. The above results are shown in the table below.

(Blank below) Effects of the Invention As described above, the present invention is particularly advantageous in that the lubricating film formed on the friction surface is a friction material that maintains its function over a long period of time. As a material, it is difficult to generate noise and meets the requirements for long life1.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the configuration of the main parts of the electromagnetic clutch and plagiar motor, and FIG. 2 is a characteristic diagram showing the relationship between temperature and dynamic friction coefficient. 12...Clutch lining, 13-...Brake lining. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Charmfulness/C

Claims (1)

[Claims] (1) A friction material consisting of a base material with organic fibers interposed between cork particles and a lubricating film formed on the friction surface of the base material. b) Claim 1 in which the organic fiber is powdered cellulose
Friction material described in section.