GB2062128A

GB2062128A - Ball bearing assembly

Info

Publication number: GB2062128A
Application number: GB8033406A
Authority: GB
Original assignee: Borg Warner Corp
Current assignee: Borg Warner Corp
Priority date: 1979-11-08
Filing date: 1980-10-16
Publication date: 1981-05-20
Also published as: BR8007181A; IT1134189B; CA1161481A; MX155574A; JPS5683617A; DE3041355A1; GB2062128B; IT8025791A0; FR2469608B1; FR2469608A1; IT8023286V0

Abstract

A ball bearing assembly comprising inner and outer races with a plurality of balls therebetween. The balls being arranged in spaced relationship by a cage 18 constructed of two like parts joined together, which cage is made of steel and preferably steel stampings and coated with a plastic material preferably a nylon, such as Nylon 11. The cage provides pockets 30 for lubricant. <IMAGE>

Description

SPECIFICATION Ball bearing assembly Ball bearing assemblies generally comprise inner and outer races with a plurality of balls therebetween, the balls being spaced apart and held in their proper operating location by a retainer. It is common practice to make the retainer of a pair of like metal stampings which are joined together. The metal can be steel or brass, as desired. Brass retainers provide superior performance to the steel retainers but are considerably more expensive.

Retainers can be of a land-riding variety and a non-land-riding or ball riding variety (as it is called), the land-riding variety having portions which contact the inner or outer race of the bearing which provides a reduction in vibration and shock effects when used in such load applications. One disadvantage of the land-riding retainers is the friction developed at the interface of the outer race. To reduce this friction, land-riding retainers have been fabricated from brass stampings instead of steel stampings, at least in high quality bearing assemblies. The cost of such brass retainers is much greater than steel retainers.

According to this invention, a land-riding retainer for a ball bearing assembly is constructed from steel stampings which are coated with a thermoplastic nylon for example "Nylon 1 1". One manufacturer of Nylon II is the Rilsan Corporation, Glen Rock, New Jersey. In the assembly, the retainer retains the advantages of brass retainers while providing increased life under marginal lubricating conditions at a significantly reduced cost. It has been demonstrated that the nylon coated steel retainers will continue to operate with little or no wear for considerable periods of time after the original lubrication supply has deteriorated.

The nylon can be applied to the steel stampings as a powder and is cured by being heated to an elevated temperature. The coating is generally on the order of 0.0025 inch to 0.050 inch thick, preferabiy 0.0025 inch to 0.008 inch, has a fusion temperature on the order of 4500F, a coefficient of friction on the order of 0.4, and a Shore "D" hardness on the order of 70 to 71.

One way of carrying out the invention is described in detail below with reference to drawings which illustrate only one specific embodiment, in which: FIG. 1 is a partial sectional view through a typical ball bearing assembly with a land-riding retainer; FIG. 2 is a perspective view of a retainer part according to this invention; and FIG. 3 is a sectionai view through the retainer of FIG. 2.

Looking at the drawing and especially FIG. 1, there is illustrated a ball bearing assembly 10 which comprises inner and outer race members 1 2 and 14, respectively, with a plurality of balls 16 therebetween. The balls 1 6 are retained and spaced in the assembly by means of a land-riding retainer 1 8 constructed of like parts 20 riveted together by rivets 22.

The retainer 1 8 is illustrated in more detail in FIG. 2 and 3 to which attention is invited. The retainer 1 8 is constructed of two like parts 20 joined by rivets 22 through openings 24. The parts are usually made by stamping the parts from sheet metal. As illustrated each part 20 is an annulus having spaced curved walls 26 which, when assembled, define pockets 28, each to receive a ball 1 6. Between the curved walls are other pockets 30 defined by the rivet wall 32 and an overlying wall 34, the latter riding on the outer race 14 of the bearing assembly 10. The pockets 30 function to retain lubricant; most bearing assemblies as described are initially factory lubricated.The parts 20 are coated, as at 36, with a thermoplastic polyamide for example "Nylon 11", one manufacturer being the Rilsan Corporation, Glen Rock, New Jersey 07452. The coating is applied as a powder either in an electrostatic process or a fluid bed process and with a thickness of 0.0025 inch to 0.050 inch and preferably 0.0025 inch to 0.008 inch and is fused at a temperature in the range of 400 to 4500 F. Data for the "Nylon 11" coating is found in an undated and uncopyrighted brochure published by Rilsan Corporation, as follows:: Property Functional Engineering Test Method Particle Size Fluid Bed 60-200 60-200 Alpine AirHet Electrostatic 0-80 0-80 Sieve A200 Minimum Film Thickness Fluid Bed 8 mils (.008") 8 mils (.008") ASTM D-1005 Electrostatic 3 mils (.003") 3 mils (.003") Coverage of 100% Utilization 160 185 1728 X.103 (ft.2/mil/lb.) 62.4 x 144 x sp. gr.

Specific Gravity &commat;23C (73'F) 1.20 1.04 ASTMD-792 Apparent Density 0.51 0.49 ASTM1895-69 Melting Point 182 -185 C 182 -185 C ASTM D-2117-64 (360 -365 F) F) (360 -365 F) Water Absorption .9 to 1.2 .9 to 1.2 ASTM D-570-63 Hardness (Shore "D") 70 71 ASTM D-2240 Abrasion Resistance 15 mg 8 mg ASTM D-1044-56 (Taber, wheel type, CS-17,1 kg load).

Loss of weight after 1000 revolutions Coefficient of Friction (Coating on Steel) Static 0289 0.382 ASTM D-1894-63 Dynamic 0.190 0.277 Tensile Strength (psi) 6200 5900 ASTM D-638 (on molded plaques) Elongation 63% 31% ASTM D-882 (on molded plaques) Coefficient of Linear Expansion 8.1 x 10-5/ C 8.8 x10-5/ C ASTM D-696 Impact Resistance (up to 160 in.-lbs.) Direct and Reverse Excellent Excellent Gardner Impact Property Functional Engineering Test Method Flammability (in./sec.) 0.4 &commat; 19 mils 02 &commat; 19 mils ASTM D-1433 Dielectric Strength .20' C (68F), 65% RH Coating Thickness .003" 4.62KV 4.91KV .005" 7.06KV 7.51KV .008" 9.93KV 10.S6KV .017" 15.34KV 16.32KV .028" 22.92KV 24-38KV Chemical Resistance ASTM D-543 A = Good, X ""'Poor ':Strong Alkalies A A Weak Alkalies A A Strong Acids X X Weak Acids A A Grease, Oil A A Chlorinated Solvents A A Alcohols A A Aromatic Solvents A A Sea Water A A Outdoor Weathering A A Boiling Water A A

Claims

1. In a ball bearing assembly having an inner race and an outer race and a plurality of balls therebetween, which balls contact the inner and outer races and are spaced by a ball retainer having spaced pockets for receiving said balls and recesses for retaining lubricant for the bearing, said retainer being constructed of a pair of like, generally circular steel parts joined together; the improvement comprising: a coating of a plastic material on said retainer having a thickness in the range of 0.0025 inch to 0.050 inch and a coefficient of friction less than 0.4 and a Shore D hardness of 70 to 71.

2. In a ball bearing assembly as recited in Claim 1, in which said plastic material has a thickness in the range of 0.0025 inch to 0.008 inch.

3. In a ball bearing assembly as recited in Claim 2 in which said plastic material in a thermoplastic.

4. In a ball bearing assembly as recited in Claim 3 in which said thermoplastic material is a fixed nylon powder.

5. In a ball bearing assembly as recited in Claim 4 in which said nylon is Nylon 11.

6. A ball bearing assembly substantially as herein described with reference to the accompanying drawing.