JPH04362311A - Retainer for rolling bearing - Google Patents

Abstract

PURPOSE:To provide a retainer for a rolling bearing made of synthetic resin which is excellent in durability in the case of using it in lubricating oil of high temperature. CONSTITUTION:To manufacture a cage for a rolling bearing of polymide with an aromatic ring in its principal chain, elastomer and reinforced fiber. The proportion of elastomer occupied in all the components is limited to a range of 5-20% by weight and the proportion of reinforced fiber to a range of 8-30% by weight.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cage for rolling bearings.

0002

[Prior Art and Problems to be Solved by the Invention] Conventionally, aliphatic polyamides such as nylon 6 and nylon 66, which are lighter than metal cages and have excellent mechanical properties, have been used as cages. Consisting of are often used. However, the aliphatic polyamide has insufficient resistance (oil resistance) when used in high-temperature lubricating oil, especially in rolling bearings of automobile transmissions, etc.
The current limit is about ~130°C, and at higher temperatures, it is still necessary to use a metal cage.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a cage for a rolling bearing made of synthetic resin that has excellent resistance particularly when used in high-temperature lubricating oil. It is an object.

0004

[Means and Effects for Solving the Problems] In order to achieve the above object, the present inventors have introduced an aromatic ring into the main chain of a linear aliphatic polyamide. We investigated the use of polyamide with improved mechanical properties and heat resistance (hereinafter referred to as "aromatic ring-containing polyamide"). This aromatic ring-containing polyamide lacks flexibility and has low impact resistance, making it easy to crack.Furthermore, it has insufficient oil resistance, and its strength decreases significantly when used in high-temperature lubricating oil. , which has conventionally been thought to be impossible to apply to cages.

However, as a result of intensive research by the present inventors, it was found that by blending an elastomer and reinforcing fibers into the aromatic ring-containing polyamide, all properties such as toughness, mechanical strength, and oil resistance can be improved. As a result of obtaining this knowledge and conducting further studies on the blending ratio of the elastomer and reinforcing fibers, etc., the present invention was completed. That is, the rolling bearing cage of the present invention contains an aromatic ring-containing polyamide, an elastomer, and reinforcing fibers, and the ratio of the elastomer to the total components is 5 to 20% by weight, and the ratio of the reinforcing fibers is 8% by weight. It is characterized by being within the range of ~30% by weight.

As the aromatic ring-containing polyamide, as mentioned above, compounds in which an aromatic ring is introduced into the main chain of a linear aliphatic polyamide (nylon), such as nylon 6, nylon 66, and nylon 46, are suitable. used for. These compounds do not lose the properties of nylon, such as good moldability, and have better mechanical properties and improved heat resistance than nylon.

The most preferred example of the aromatic ring-containing polyamide is Ultramid T, a trade name manufactured by BASF. This compound is made by reacting caprolactam, hexamethylene diamine, and terephthalic acid, and in the general formula (I) below, the caprolactam moiety shown on the left and the hexamethylene diamine-terephthalic acid moiety shown on the right are randomly bonded. It has a random copolymer structure.

[0008]

[Chemical 1] Elastomers include natural rubber; butadiene rubber, isoprene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, ethylene-butadiene rubber,
Synthetic rubbers such as propylene rubber; thermoplastic elastomers such as styrene-based, olefin-based, urethane-based, polyester-based, polyamide-based, and polyvinyl chloride-based are exemplified.

[0009] The proportion of elastomer in all components is
It is limited within the range of 5 to 20% by weight. If the proportion of the elastomer is less than 5% by weight, the effect of adding the elastomer will not be obtained and the oil resistance will decrease, and if the proportion of the elastomer is less than 20% by weight, the oil resistance will decrease.
If it exceeds % by weight, the proportion of aromatic ring-containing polyamide decreases relatively, resulting in deterioration of mechanical properties and
Heat resistance decreases.

The above-mentioned aromatic ring-containing polyamide and elastomer can be used alone as a mixture, or as a block copolymer or a graft copolymer of the two. Examples of reinforcing fibers include glass fiber, carbon fiber, fibrous wollastonite, silicon carbide fiber, boron fiber, alumina fiber, Si-Ti-C-
Examples include O fibers, metal fibers (copper, steel, stainless steel, etc.), aromatic polyamide (aramid) fibers, potassium titanate whiskers, graphite whiskers, silicon carbide whiskers, silicon nitride whiskers, alumina whiskers, and the like.

[0011] The proportion of reinforcing fibers in all components is 8 to 8.
It is limited within the range of 30% by weight. The ratio of reinforcing fibers is 8
If it is less than % by weight, the effect of adding the reinforcing fiber cannot be obtained,
Toughness deteriorates and heat resistance decreases. On the other hand, if the proportion of reinforcing fibers exceeds 30% by weight, the flexibility decreases, especially in the case of an undercut shape, for example, when the molded product is removed from the mold or the rolling elements are press-fitted into the pocket. This causes cracks and cracks to occur in the undercut portion.

The cage for rolling bearings of the present invention is produced by melting and kneading the above-mentioned components to form pellets, powders, or other forms that can be used as molding materials, and then processing the cages in an injection molding machine, etc. in the same manner as in the past. It is manufactured by molding using. The structure of the present invention can be applied to cages of all shapes for various rolling bearings such as ball bearings, needle roller bearings, cylindrical roller bearings, tapered roller bearings, etc., and in particular cages of shapes with undercuts. It can be suitably applied to a cage.

[0013]

[Example] Using the molding materials of the following formulation examples, the tests described below were conducted. <Blend Example> Blend Example 1 The above general formula (I) as an aromatic ring-containing polyamide
A molding material containing 85% by weight of a compound represented by: 5% by weight of an elastomer and 10% by weight of glass fibers.

Formulation Example 2 The above general formula (I) as an aromatic ring-containing polyamide
70% by weight of the compound represented by, 10% by weight of the elastomer
and a molding material containing 20% by weight of glass fibers. Formulation Example 3 The above general formula (I) as an aromatic ring-containing polyamide
50% by weight of the compound represented by, 20% by weight of the elastomer
and a molding material containing 30% by weight of glass fibers.

Formulation Example 4 The above general formula (I) as an aromatic ring-containing polyamide
A molding material consisting only of the compound represented by. Formulation Example 5 The above general formula (I) as aromatic ring-containing polyamide
A molding material containing 75% by weight of the compound represented by and 25% by weight of glass fibers.

Formulation Example 6 The above general formula (I) as aromatic ring-containing polyamide
A molding material containing 80% by weight of a compound represented by and 20% by weight of an elastomer. Formulation Example 7 The above general formula (I) as aromatic ring-containing polyamide
50% by weight of the compound represented by, 10% by weight of the elastomer
and a molding material containing 40% by weight of glass fibers.

Formulation Example 8 The above general formula (I) as aromatic ring-containing polyamide
50% by weight of the compound represented by, 30% by weight of the elastomer
and a molding material containing 20% by weight of glass fibers. Formulation Example 9 Molding material containing 75% by weight of aliphatic polyamide (nylon 66) and 25% by weight of glass fibers. <Test> Tensile test ASTM D 638-82a "Standard
Test Method for TENSILE P
The tensile strength at break (kgf/cm2) and tensile elongation at break (%) of the molding materials of each of the above formulation examples were measured in accordance with ``ROPERTIES OF PLASTICS''. Note that, for the measurement, Type I test pieces prepared from the molding materials of each blending example were used.

Bending test ASTM D 790-81 "Standard"
Test Method for FLEXURAL
PROPERTIES OF UNREINFORCE
D AND REINFORCED PLASTICS
AND ELECTRICAL INSULATIN
The bending strength (kgf/cm
2) was measured. In addition, for the measurement, 5 inch length x 1/2 inch width x 1/2 inch width fabricated from the molding material of each formulation example.
A test piece with a height of 1/4 inch was used.

[0019] Also, the above ASTM D 790-1
According to the formula described in Section 1.11, the flexural modulus (kgf/c
m2) was calculated. Izod impact test ASTM D 256-81 “Standard
Test Method for IMPACT RE
SITANCEOF PLASTICS AND EL
ECTRICAL INSULATION MATER
The Izod impact strength (kgf·cm/cm) of the molding materials of each of the above formulation examples was measured in accordance with ``IALS (Test Method for Impact Resistance Properties of Plastics and Electrical Insulators)''. In addition, for the measurement, the molding material made from the molding material of each formulation example,
A test piece with a 1/8 inch notch was used.

Formability test The molding materials of each of the above compounding examples were pelletized, and using an injection molding machine, a cage for a needle roller bearing having an outer diameter of 57 mm, an inner diameter of 50 mm, a width of 34 mm, and a number of pockets of 27 was formed. The presence or absence of cracks or cracks in the undercut portion was observed. Measurement of Cage Strength Samples S were prepared by cutting the cage that did not show cracks or cracks in the above moldability test by two pockets. The protrusions 21, 2 of the pair of jigs 2, 2 are placed in the pockets 11, 11 of the
Initial value S1 of the breaking strength when the jigs 2, 2 are pulled up and down as shown by the arrows in the figure with 1 inserted.
(kgf) was measured.

Next, the breaking strength S2 of the cage after immersing the cage in gear oil at 140° C. for 500 hours (for formulation example 9, 500 hours in gear oil at 120° C.)
(kgf) was measured in the same manner as above. Furthermore, the initial value S1 of the above-mentioned breaking strength and the breaking strength S2 after heat resistance are determined.
From the following formula (1), the retention rate of breaking strength RS
(%) was calculated.

[0022]RS (%)=S2/S1×100...
(1) The above results are shown in Tables 1 and 2.

[0023]

[Table 1]

[0024]

[Table 2] From the results in Tables 1 and 2 above, it was found that Blend Example 4, which contained no elastomer or glass fiber and contained only aromatic ring-containing polyamide, was brittle and had poor oil resistance. In addition, Formulation Example 5, which does not contain elastomer, shows improvement in mechanical properties, but still has poor oil resistance.On the contrary, Formulation Example 6, which does not contain glass fiber, is brittle and has poor oil resistance. Ta.

[0025] Formulation Example 7, in which the glass fiber content exceeds 30% by weight, lacks flexibility and cracks occur in the moldability test, while Formulation Example 8, in which the elastomer content exceeds 20% by weight. was found to be brittle and have poor oil resistance. Furthermore, it was also found that the conventional blending example 9 consisting of aliphatic polyamide and glass fiber had extremely poor oil resistance.

On the other hand, formulation examples 1 to 3, which are component formulations of the cage for rolling bearings of the present invention, all have excellent mechanical properties as well as flexibility and oil resistance. found.

[0027]

[Effects of the Invention] Since the rolling bearing cage of the present invention is constructed as described above, it has excellent durability particularly when used in high-temperature lubricating oil.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are explanatory diagrams showing a method for measuring the strength of a cage for a needle roller bearing.

Claims (1)

[Claims] Claim 1: A polyamide having an aromatic ring in its main chain;
A cage for rolling bearings containing an elastomer and reinforcing fibers, wherein the proportion of the elastomer in the total components is within the range of 5 to 20% by weight, and the proportion of the reinforcing fibers is within the range of 8 to 30% by weight. .