JPH0665892B2 - bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a novel bearing (rolling bearing).

<Prior Art> In recent years, bearings have been widely used. For example, from the bearings for jet engines to the ultra-compact bearings for dental handpieces, as well as vehicles, electric motors, and various machines, their application fields are extremely wide.

Therefore, the materials used for these bearings are not limited to the high carbon chrome bearing steels that have been used in the past, but also a wide variety of materials such as general structural steels, blazing steels, stainless steels, and high speed steels. Metals have come into use.

<Problems to be Solved by the Invention> Bearings made of these metals have been used in a wide range of fields because of their high precision, durability, and low cost. There are various problems such as a large size, which cannot be used in a vacuum because a lubricating oil is required, and the function of the lubricating oil is deteriorated to easily cause seizure when used for a long time at a high temperature even in air.

In order to solve these problems, it is generally considered that the material of the bearing should be changed to a polymer material, but fluoropolymer or nylon resin, which is a typical polymer material with self-lubricating property, does not Since the working precision in making was insufficient, and the heat resistance, durability, dimensional stability, etc. were inferior, it could not be made into a practical bearing.

Therefore, an object of the present invention is to solve the above-mentioned problems in conventional bearings, to provide a bearing with low working noise, which can be stably used for a long period of time without the need for lubricating oil, and which has good working accuracy. It is in.

<Means for Solving the Problem> A bearing according to the present invention is a bearing in which a plurality of rolling elements are interposed between an outer ring and an inner ring, and at least the rolling element has an aromatic polyamide short fiber length of 4 mm or less. A total of at least one of fibers, pulp-like particles made of aromatic polyamide, and aromatic polyamide fiber cloth is 30
The bearing is characterized in that it is an aromatic polyamide resin containing less than or equal to wt%.

That is, FIG. 1 to FIG. 3 are cross-sectional views showing examples of the bearing of the present invention. The bearing of the present invention has a plurality of balls (balls) 3 between the outer ring 1 and the inner ring 2.
Alternatively, a rolling element such as a roller (roller) 4 is interposed to perform a bearing function, and at least the rolling element such as the ball 3 or the roller 4 is made of an aromatic polyamide resin.

Since this bearing does not require a lubricating oil due to the characteristics of the aromatic polyamide resin as described below, a seal is not required for the purpose of preventing the leakage of the lubricating oil. As shown in the figure, seals 5 may be provided at both ends. Further, a retainer 6 for the ball 3 or the roller 4 may be provided if necessary.

In the present invention, the outer ring 1 and the inner ring 2 may be made of a metal such as the above-mentioned various steels, but one or both of them are aromatic polyamide resin or other synthetic resin with high accuracy, heat resistance and durability. It may be made of resin.

In the present invention, the aromatic polyamide resin constituting the rolling elements in the bearing is preferably a homopolyamide or copolyamide in which 55 mol% or more of the polymer repeating units are metaphenylene isophthalamide units.

Such a homopolyamide or copolyamide uses isophthalic acid halide as an acid component and metaphenylenediamine as a diamine component, and further a small amount of a third component, for example, terephthalic acid halide, methyl terephthalic acid halide, naphthalene-2, Producing by condensation of 6-dicarboxylic acid halide, paraphenylenediamine, 3,4'- or 4,4'-diaminodiphenyl ether, metaxylylenediamine, etc. or meta or parabenzoic acid halide, etc. You can

Homopolyamide of poly (metaphenylene isophthalamide) or copolyamide containing more than 85 mol% of metaphenylene isophthalamide unit is the strength, heat resistance, hardness, flexibility, self-lubricating property when processed into balls, rollers, etc. Although it has excellent properties, it has a slightly inferior impact resistance. Therefore, if impact resistance is required,
20-60 mol% of polymer repeating units (preferably 30-45)
It is particularly preferable to use a copolyamide in which (mol%) is a metaphenylene terephthalamide unit and 80 to 40 mol% (preferably 70 to 55 mol%) is a metaphenylene isophthalamide unit.

Such an aromatic homopolyamide or copolyamide has an intrinsic viscosity (ηinh) of 0.5 to 4. measured by a solution of 0.5 g of polymer dissolved in 100 m of N-methyl-2-pyrrolidone at 30 ° C.
Those having an intrinsic viscosity of 0.7 to 2.5 are particularly preferable because they have excellent moldability and good physical properties of molded articles (balls, rollers, etc.).

These aromatic polyamides may contain additives such as stabilizers, matting agents, colorants and fillers.

Bearings used in fields where impact resistance is particularly required include rolling elements such as balls and rollers, or the whole of the aromatic polyamide, and a reinforcing fibrous material in an amount of 3 to 30 relative to the polymer.
Suitably, it is composed of a mixture in which the components are mixed by weight.

As the reinforcing fibrous material, a short-cut fiber of aromatic polyamide fiber, a pulp-like particle of aromatic polyamide, or a cloth made of aromatic polyamide is suitable.

As an aromatic polyamide fiber, "Conex ],
"NOMEX Known as trade names such as poly (metaphenylene
Isophthalamide) fiber, “Kevlar "Twaron "
Poly (paraphenylene terephthalate)
Amide) fiber or described in Japanese Patent Publication No. 54-43612
Such as 3,4-diaminodiphenyl ether
Para-aromatic copolyamide fiber (trade name)
"Technora ]) Is appropriate. These fibers directly
When mixing, fiber length (cut length) of 4 mm or less
Used as a shortcut fiber below. Said goodness
If the fiber length of aromatic polyamide fibers exceeds 4 mm, the mixture
The dispersibility of the fibers inside deteriorates sharply and the moldability deteriorates.
Become.

On the other hand, as the pulp-like particles of the aromatic polyamide, pulp-like particles made of a polymer similar to the fiber are suitable, and a method of introducing the polymer solution into a coagulation bath to which shearing force is applied to cause precipitation ( For example, JP-B-35-11851), a method of precipitating a polymer in the form of pulp in the polymerization process of aromatic polyamide (for example, JP-B-59-14569 and JP-B-60-56801).
No.) and a method of beating the fibers to form pulp-like particles (for example, JP-B-59-603).

The reinforcing cloth is woven or knitted from the aromatic polyamide fiber used when the shortcut fiber is made.

The mixing ratio of the reinforcing fibrous material (for example, short-cut fibers, pulp-like particles, etc.) to the aromatic polyamide resin is appropriately in the range of 3 to 30% by weight based on the weight of the polymer, and particularly 5 to 25% by weight is preferred. When the amount of the reinforcing fibrous material is less than 3% by weight, the effect of mixing the fibrous material is poor. On the other hand, when it exceeds 30% by weight, it is difficult to uniformly disperse the fibrous material in the polymer at the time of molding and the moldability is deteriorated. Not only that, but it tends to cause a problem that the molded product becomes brittle.

For the production of the aromatic polyamide resin and the molding of the rolling element, a conventionally known method can be adopted, and in particular, as described in European Patent Application Publication No. 0198167 (October 22, 1986), the interface weight It is preferable that compression-molding is performed using the agglomerated aromatic polyamide particles having a specific particle structure obtained by the legal method, and then cutting processing is performed to form rolling elements such as balls and rollers. However, other methods such as those disclosed in Japanese Patent Publication No. 56-2092 and Japanese Patent Laid-Open No. 60-203418 may be used.

<Effects of the Invention> In the bearing of the present invention, since at least the rolling elements such as balls or rollers are made of an aromatic polyamide resin as described above, the sound during use is extremely low, and the aromatic polyamide resin is Excellent surface hardness, mechanical properties, heat resistance, dimensional stability, etc., and machining accuracy (sphericity in the case of balls)
The bearing of the present invention has an advantage that it can be stably used for a long time in vacuum or at high temperature without lubricating oil because it has good self-lubricating property. Further, since it has a significantly higher machining accuracy than other rigid resins, it can be used in a wide range of applications from ultra-small to large bearings.

In particular, it is suitable as a bearing for acoustic equipment, a bearing for medical equipment, which is disliked in the generation of sound, an aircraft used in or near a vacuum, parts for artificial satellites, and the like.

<Example> The present invention will be described in detail with reference to Examples below, but the present invention is not limited thereto.

Example 1 (a) Production of polymer Poly (metaphenylene isophthalamide) containing no inorganic salt was prepared according to the interfacial polymerization method described in JP-B-47-10863.
A polymer was produced.

That is, 173 g of metaphenylenediamine was dissolved in tetrahydrofuran 1 dehydrated with sodium metal and cooled to 0 ° C. Meanwhile, isophthalic acid chloride 325
Tetrahydrofuran 1 g of which was dehydrated with sodium metal
And was cooled to 0 ° C. Next, the tetrahydrofuran solution was stirred while maintaining the temperature at 0 ° C., and the isophthalic chloride solution was gradually added to this as a trickle to obtain a dispersion of the initial condensate (first reaction).

Subsequently, the dispersion liquid of the initial condensate was rapidly added to a solution of 200 g of sodium carbonate dissolved in water 2 under high speed stirring,
White polymer particles having an intrinsic viscosity of 1.8 were obtained (second reaction).

The surface area of the polymer particles was 4.0 m ³ / g, and the apparent bulk density was 0.35 g / cc.

(B) Molding Using the above polymer particles, compression molding was carried out under the conditions of a heating temperature of 320 ° C. and a pressure of 330 kg / cm ² and a pressure of 40 minutes. The physical properties of the obtained molded product were Rockwell hardness (M scale) 125 degrees, tensile strength 11.5 kg / mm ² tensile elongation 4.2% modulus 346 kg / mm ² Izod impact value 2.8 kg · cm / cm.

(C) Processing The above-mentioned molded product was cut and further polished to make a ball having a diameter of 5 mm, and a bearing having this as a rolling element was manufactured. As a result of using this bearing, it was confirmed that there was almost no sound.

When this was used in a vacuum, almost no gas was generated and no seizure occurred. It was also confirmed that it has the required durability.

[Brief description of drawings]

1 to 3 are cross-sectional views showing an example of the bearing of the present invention, wherein 1 is an outer ring, 2 is an inner ring, 3 is a ball, 4 is a roller, 5 is a seal, and 6 is a cage.

Claims (1)

[Claims] 1. A bearing in which a plurality of rolling elements are interposed between an outer ring and an inner ring, wherein at least the rolling elements are aromatic polyamide short fibers having a fiber length of 4 mm or less, pulp particles made of aromatic polyamide, and aroma. A bearing comprising an aromatic polyamide resin containing at least 30% by weight in total of at least one kind of group polyamide fiber cloth.