JPH0742745A - Retainer for rolling bearing - Google Patents

Abstract

PURPOSE:To improve heat resistance by containing a glass fiber in a polyamide resin base material as a reinforced fiber, and constricting this glass fiber by polturethane binder. CONSTITUTION:As for polyamide resin, various type of well-known aliphatic resins excellent in flexibility, such as nylon 6, especially nylon 46 or the like excellent in heat resistance, by way of example, are used. As for a reinforced glass fiber to be contained in the polyamide resins, such one made up of constricting a mass of filament of 200 pieces or so being surface-treated by a coupling agent including or the like is used. As to a epoxyurethane binder in use for convergence, epoxy resin with more than two pieces of an epoxy radical at the terminal and further at need, such one mixed with a hardner or curing catalyst are used in a composition of various types of this well-known epoxyurethane binder is adopted. Since such a binder as being excellent in lubricating oil resistance at a temperature at a temperature somewhere near high temperature limits is used, a retainer is able to make a strength drop in and around the high temperature limits reducible in this way.

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]

2. Description of the Related Art As a cage, a polyamide resin such as nylon 46 or nylon 66, which is lighter in weight than a metal cage and has excellent mechanical properties, can be used as a cage. In order to provide necessary strength and heat resistance, those containing reinforcing fibers such as glass fibers are often used.

However, the above cage made of polyamide has a problem that it has a limit temperature at which it can be used at a high temperature, and its strength is greatly reduced near the high temperature limit. Instead of the polyamide resin, it is possible to use so-called super engineering plastics that can be used at higher temperatures, such as polyether sulfone (PES) and polyether ether ketone (PEEK), but most of the super engineering plastics are used. However, because it is less rigid than polyamide resin and has a high rigidity, especially when the pocket for holding the rolling element is undercut, for example, the molded product is removed from the mold or transferred to the pocket. When pressing the moving body,
There is a possibility that cracks or cracks may occur in the undercut portion.

When a rolling bearing is used, if it is made of a flexible polyamide resin, the rolling element may move forward or backward due to rotation.
Since it can be absorbed by its own deformation, there is no risk of cracking, but a rigid cage made of super-engineering plastic cannot absorb the advance or lag of the rolling element, and therefore there is a risk of cracking due to the impact of the rolling element collision.

The present invention has been made in view of the above circumstances, and uses a polyamide resin having excellent flexibility, and has a small decrease in strength near the high temperature limit and is excellent in heat resistance for rolling bearings. The purpose is to provide a retainer.

[0006]

Means and Actions for Solving the Problems In order to solve the above problems and improve the heat resistance of a cage using a polyamide resin, the present inventors have examined the cause of strength reduction near the high temperature limit. I went. As a result, they have found that the deterioration of the sizing agent that bundles the glass fibers as the reinforcing fibers is one of the causes of the strength reduction.

The glass fiber is generally used by bundling about 200 filaments whose surface is treated with a coupling agent such as aminosilane, and cutting the filament to a length of 3 to 9 mm. A sizing agent of acrylic-urethane type or urethane type is applied. The sizing agent applied to the glass fibers also has a function of connecting the glass fibers at the interface when the glass fibers are dispersed in the polyamide resin.

However, under temperature conditions near the high temperature limit,
When lubricating oil such as gear oil or grease used for rolling bearings penetrates into the cage, the sizing agent in contact with it deteriorates and loses the function of connecting glass fibers to each other and to the glass fiber and polyamide resin. Therefore, the function of reinforcing the polyamide resin is impaired, and the strength of the cage sharply decreases.

Therefore, under temperature conditions near the high temperature limit,
As a result of further investigation for a sizing agent having excellent resistance to lubricating oil, it was found that an epoxy-urethane sizing agent is optimal for achieving the intended purpose, and the present invention was completed. It was That is, the rolling bearing retainer of the present invention is a rolling bearing retainer in which glass fibers as reinforcing fibers are contained in a polyamide resin base material, and the glass fibers are bound by an epoxy-urethane sizing agent. Is characterized by.

As the polyamide resin, various conventionally known aliphatic polyamide resins having excellent flexibility such as nylon 6, nylon 66, nylon 46, etc. can be used, and among them, particularly excellent heat resistance. nylon 46, i.e. the reaction product of 1,4-diaminobutane and adipic acid, the following general formula (1): - _{[HN- (CH 2) 4 -NH-} CO- (CH 2) 4 -CO ] -A polyamide resin having a repeating unit represented by (1) is most preferably used. Further, in the case of a cage having a shape without undercut, a relatively rigid polyamide having an aromatic ring in the main chain, such as nylon MXD6, can be used. These polyamide resins can be used alone or in combination of two or more.

As the glass fiber contained in the polyamide resin, about 200 filaments whose surfaces are treated with a coupling agent such as aminosilane are bundled in the same manner as in the prior art, and the filaments are made to have a length of 3 to 9 mm. The cut product is preferably used. As the glass fiber, alkali-free E-glass (Electrical Glass) or S-
Those made of various conventionally known glass materials such as non-alkali aminosilicate glass called strong glass are used.

The filament diameter of the glass fiber is not particularly limited, but is preferably about 6 to 13 μm. If the filament diameter is small, the number of glass fibers per unit weight increases, and the area of adhesion with the polyamide resin increases, so that the initial reinforcing effect increases. However, if the filament diameter is less than 6 μm, the lubricating oil penetrates into the interface between the polyamide resin and the glass fiber, and the peeling area is large when the adhesion between the two is peeled off. On the other hand, if the filament diameter exceeds 13 μm,
Since the number of glass fibers per unit weight is reduced and the adhesion area with the polyamide resin is reduced, the effect of peeling due to the penetration of lubricating oil is reduced, but the initial reinforcing effect may be insufficient.

The blending ratio of the above glass fibers in all the components may be the same as in the conventional case, that is, about 20 to 40% by weight. If the blending ratio of the glass fibers is less than 20% by weight, the effect of adding the glass fibers may not be sufficiently obtained, the toughness may be lowered, and the heat distortion temperature may be lowered. on the other hand,
If the blending ratio exceeds 40% by weight, the flexibility decreases,
Particularly in the case of an undercut shape, cracks or cracks may occur in the undercut portion when the molded product is removed from the molding die or the rolling element is pressed into the pocket.

Epoxy used for focusing glass fibers
As the urethane-based sizing agent, an epoxy resin having two or more epoxy groups at the end is added to the composition of conventionally known various types of polyurethane-based sizing agents, and further, a curing agent or a curing agent for curing the same. A mixture with a catalyst is used. Examples of the polyurethane-based sizing agent that is the basis of the epoxy-urethane-based sizing agent include polyisocyanates containing various conventionally known polyisocyanates such as triphenylmethane triisocyanate and tris (4-phenylisocyanate) thiophosphate as the polyurethane resin component. Type polyurethane sizing agent, prepolymer type polyurethane sizing agent obtained by reacting diisocyanate and polyfunctional active hydrogen compound and having a prepolymer having an NCO group at the end as a polyurethane resin component, bifunctional or higher functional polyester , Polyether was polymerized by chain extension reaction with diisocyanate,
Examples thereof include a polymer having an H group as a polyurethane resin component and, if necessary, a small amount of polyisocyanate, or an isocyanate-modified polymer type polyurethane sizing agent to which a prepolymer having an NCO group at the terminal is added.

Examples of the epoxy resin include glycidyl ether type, glycidyl ester type, and glycidyl obtained by condensation reaction of a glycidyl compound such as glycidyl alcohol and epichlorohydrin with a polyhydric alcohol containing a polyhydric phenol, a polyvalent carboxylic acid or an amine. Conventionally known various types and grades of epoxy resins such as amine type epoxy resins, non-glycidyl type epoxy resins obtained by oxidizing a double bond of an olefin compound or a cyclohexene ring can be used.

The curing agent and curing catalyst are not particularly limited, and among various conventionally known curing agents and curing catalysts such as amine-based, polyaminoamide-based, acid and acid anhydride-based curing agents, An optimum resin may be used according to the type of the epoxy resin. The epoxy-urethane-based sizing agent has higher heat resistance and oil resistance than conventional acrylic-urethane-based sizing agents and urethane-based sizing agents, and even if it comes into contact with lubricating oil near the high temperature limit, Since it does not deteriorate, it has the effect of suppressing the strength decrease of the cage near the high temperature limit and improving its heat resistance.

The epoxy resin contained in the epoxy-urethane sizing agent is excellent in compatibility and adhesion with the polyamide resin and has a high function of connecting the glass fibers to each other and the glass fiber and the polyamide resin. It acts to strengthen the function of the polyamide resin reinforcement by the fibers and improve the strength of the cage. Furthermore, the polyurethane component is
It prevents the glass fibers from deteriorating due to the intrusion of water into the polyamide resin, thereby preventing the boundary separation of the glass fibers.

These sizing agents are preferably applied in a proportion of 0.2 to 5% by weight, for example, to E-glass filaments. The rolling bearing cage of the present invention,
In addition to the above components, various additives such as an inorganic filler as a colorant and a copper-based or organic stabilizer,
It may be contained in the same ratio as in the conventional case.

In addition to glass fibers, carbon fibers, fibrous wollastonite, silicon carbide fibers, boron fibers, alumina fibers, Si--Ti--C--O fibers, metal fibers (copper, steel, Other reinforcing fibers such as stainless steel), aromatic polyamide (aramid) fibers, potassium titanate whiskers, graphite whiskers, silicon carbide whiskers, silicon nitride whiskers, alumina whiskers, etc.
They may be used alone or in combination of two or more.

In the rolling bearing cage of the present invention, the above components are melted and kneaded into pellets, powders or the like into a shape that can be used as a molding material, and then an injection molding machine or the like is used in a conventional manner. It is manufactured by molding using.

[0021]

EXAMPLES The present invention will be described below based on Examples and Comparative Examples. Example 1 <Preparation of epoxy-urethane sizing agent> An epoxy-urethane sizing agent was prepared by mixing a urethane resin and an epoxy resin in a weight ratio of 3: 7. <Production of molding material> 200 E-glass filaments having a diameter of 10 μm, the surface of which has been treated with an aminosilane-based coupling agent, are bundled, and the epoxy-urethane-based sizing agent is applied to the E-glass filaments 4 times. A glass fiber was manufactured by coating the composition at a weight percentage and then cutting it to a length of 3 to 9 mm.

Then, the above glass fibers were blended in a proportion of 30% by weight with respect to nylon 46 as a polyamide resin base material, further a small amount of stabilizer was added, and then melt-kneaded and pelletized by a pelletizer, An injection molding pellet as a molding material was produced. <Manufacture of Crown Type Ball Bearing Cage> Using the above injection molding pellets, a crown type ball bearing cage H having a shape shown in FIG. In the figure, reference symbol G indicates a gate position, and reference symbol H1 indicates a weld line of a molded product which is generated at a position symmetrical to the gate position G.

Comparative Example 1 The same as Example 1 except that an acrylic-urethane sizing agent prepared by mixing a urethane resin and an acrylic resin in a weight ratio of 3: 7 was used for sizing the glass fiber. Similarly, injection molding pellets as a molding material were manufactured, and a crown type ball bearing cage was manufactured using the injection molding pellets.

Comparative Example 2 An injection-molding pellet as a molding material was produced in the same manner as in Example 1 except that the urethane resin was used as it was as a urethane-based sizing agent to focus the glass fibers. A cage for a crown type ball bearing was manufactured using the molding pellets. Comparative Example 3 Except that the acrylic-urethane sizing agent was applied at a ratio of 2% by weight to the filament made of E-glass,
Injection molding pellets as a molding material were manufactured in the same manner as in Comparative Example 1 above, and a cage for a crown type ball bearing was manufactured using the injection molding pellets.

Comparative Example 4 Pellets for injection molding as a molding material were prepared in the same manner as in Comparative Example 2 except that the urethane sizing agent was applied to the E-glass filament at a ratio of 2% by weight. Was manufactured, and a cage for a crown type ball bearing was manufactured using this injection molding pellet.

The following tests were conducted on each of the above Examples and Comparative Examples. Cage Strength Measurement (Initial Value) As shown in FIGS. 2 (a) and 2 (b), the cage H for the crown type ball bearing is arranged so that its weld line H1 is arranged between the pair of jigs 1 and 2. Mounted on the projections 11 and 12, and the jigs 1 and 2 are
The initial value (N) of the breaking strength when pulled up and down was measured as indicated by the white arrow in the figure.

Cage strength measurement (after heat resistance) Grease was applied to the surface of the cage H for crown type ball bearings, and 18
After standing in an atmosphere of 5 ° C. for 500 hours, the breaking strength (N) after heat resistance was measured in the same manner as above. The following tests were carried out on the injection molding pellets used as the molding material for the cages for crown type ball bearings of the above Examples and Comparative Examples.

Tensile Test ASTM D 638-82a [Standard Test Method
for TENSILE PROPERTIES OF PLASTICS] (Tensile PROPERTIES OF PLASTICS)
Pa) was measured. A Type I test piece prepared from each molding material was used for the measurement.

Bending test ASTM D 790-81 [Standard Test Method f
or FLEXURAL PROPERTIES OF UNREINFORCED AND REINFOR
CED PLASTICS AND ELECTRICAL INSULATING MATERIALS
(Bending strength (MPa) was measured according to (Testing method for bending properties of reinforced or unreinforced plastic and electrical insulator)]. For the measurement, a test piece having a length of 5 inches, a width of 1/2 inch, and a height of 1/4 inch was used.

Izod impact test ASTM D 256-81 [Standard Test Method f
or IMPACT RESISTANCEOF PLASTICS AND ELECTRICAL INS
Izod impact strength (J / m) was measured according to ULATING MATERIALS (testing method for impact resistance of plastics and electrical insulators). For the measurement, a test piece having a notch of 1/8 inch made from each molding material was used.

The results of each of the above tests are shown in Table 1.

[0032]

[Table 1]

From the results of the material tests shown in Table 1 above, the molding material used in Example 1 has the same bending strength and Izod impact strength as the molding material used in each comparative example, and the tensile rupture strength. It was found that it is flexible, has excellent impact resistance, and has high strength. Further, from the results of measuring the cage strength, the cage for the crown type ball bearing of Example 1 was
Since the cage strength after heat resistance was higher than that of each comparative example, it was confirmed that the cage had excellent heat resistance.

[0034]

As described in detail above, according to the present invention, an epoxy having excellent resistance to lubricating oil under temperature conditions near the high temperature limit is used as a sizing agent for sizing glass fibers contained in a polyamide resin matrix. -Because a urethane sizing agent is used, the cage has a small decrease in strength near the high temperature limit and has excellent heat resistance.

[Brief description of drawings]

FIG. 1 is a perspective view showing a cage for a crown type ball bearing as an embodiment of a rolling bearing cage according to the present invention.

2A and 2B are a front view and a side view showing a strength measuring method of a cage for a crown type ball bearing.

Claims (1)

[Claims] 1. A cage for rolling bearings, comprising a polyamide resin matrix containing glass fibers as reinforcing fibers, wherein the glass fibers are bundled by an epoxy-urethane sizing agent. Retainer.