ROLLING ELEMENT BEARING

Abstract: Cages of large bearings are normally made of plate-steel or brass. Due to relativelly high speed excessive wear, noise and surface defects develop between the cage (7) and rolling bodies (1). The claimed design obviates these known disadvantages by covering the contact area (11) between cage-pockets and rolling bodies with a rubber layer (13) whereby the thickness of the layer should preferably be in order of 0.5-0.05 times the cage material thickness. This makes it possible to take up large forces between rolling bodies and the cage without crushing the rubber layer. The lubri­ cant film thickness will be 10 to 100 times larger than in a steel or plastic cage and therefore an optimum hydro-dynamic lubrication obtained. Besides high degree in manufacturing the cage or rubber layers is not required as long as the errors in form and surface roughness can be taken up by elastic deformation of the rubber layer (13). Further the oil film thickness will be less sensitive to local loads and pressures.

Description: The invention concerns a rolling element bearing equipped with rolling elements held between an inner and an outer race of the bearing and kept separate from one another by a bearing cage which is formed by an annular component consisting of one or more parts in which, along the circumference and at equal distances from one another, partially or fully enclosed pockets have been formed which each contain a rolling element, the walls of the pockets being coated entirely or partially with a rubber coating. Such a rolling element bearing is known from US-A-2712481. The aim of the invention is to provide a rolling element bearing of the above type, the bearing cage of which can be manufactured with less accuracy and thereby more easily. This aim is achieved in that the size of the rubber-coated pockets is smaller than the size of the rolling elements to such a degree that the rubber coating around the mounted rolling elements is elastically deformed. As a result, there is no need for the manufacturing tolerances of the bearing cage material and of the rubber coating to be particularly accurate, because any deviation in size or any error in shape will be compensated by the elastic deformation of the rubber coating. Furthermore, the elasticity of the rubber coating makes it possible to mount the rollers with relatively little pressure through the narrower openings for insertion into the pockets of the bearing cage, thus preventing damage to the rollers. Moreover, a similar roller bearing will run very quietly because there is no play between the rollers and the pockets of the bearing cage, and also on account of the damping properties of the rubber coating. It should be pointed out that it is generally known, among others from the American patent mentioned above, i.e., US-A-2 712 481 and also US-A-3 938 866, that in bearing cages of the so-called snap type the openings through which the rollers are inserted into the bearing cage are slightly smaller than the rollers themselves. Consequently, the insertion of the rollers will occur under a certain pressure whereby the openings are elastically deformed and in the case of US-A-3 938 866 surface damage occurs to the rollers. In addition, the pockets in the bearing cage which enclose the mounted rollers are designed to be larger than the rollers so that there will be a certain amount of play between the rollers and the pockets and there will be no question of a certain pre-tension of the cage with regard to the rollers. According to a further elaboration of the invention the thickness of the rubber coating is preferably 0.5 to 0.05 times the thickness of the bearing cage material. This thickness has proved sufficient for the absorption of major forces between the rollers and the bearing cage without damaging the rubber coating or causing it to tear away from the cage. For heavy-duty industrial applications the rubber coating can be further reinforced with a mesh, fabric or strong fibers. The invention is further explained with the help of the drawings in which two forms of execution of a roller bearing according to the invention are represented. Figure 1 shows a perspective view of the roller bearing according to the invention. Figure 2 shows a perspective view of a ball bearing. As shown in the figures, the rolling element bearings consists of a number of rolling elements 1, 2 which are held between an inner race 3, 4 and an outer race 5, 6 of the bearing and are kept separate from one another by a bearing cage 7, 8. The bearing cage consists of an annular component which is equipped,along its circumference and at equal distances from one another, with pockets 9, respectively 10, which enclose partially the rolling elements 1, 2. Figure 1 shows a bearing cage 7 of the so-called window type which finds application, for example, in roller bearings. In this case the openings 9 are rectangular. The bearing cage 8 in Figure 2 is equipped with round openings 10 which are common, for example, in ball bearings. In this case the bearing cage consists of two parts which are rivetted together. The walls 11, 12 of, respectively, pockets 9 and 10 are coated with a rubber coating 13, respectively 14. This coating can be reinforced with a mesh, fabric or strong fibers. It will be obvious that the invention is not limited to the examples of execution described above which, within the scope of the invention, can undergo several variations.

Claims: A rolling element bearing equipped with rolling elements (1, 2) held between an inner (3, 4) and an outer race (5, 6) of the bearing and kept separate from one another by a bearing cage (7, 8) which is formed by an annular component consisting of one or more parts in which, along the circumference and at equal distances from one another, partially or fully enclosed pockets (9, 10) have been formed which each contain a rolling element (1, 2), the walls (11, 12) of the pockets being coated entirely or partially with a rubber coating (13, 14) characterized by the fact that the size of the rubber-coated pockets (9, 10) is smaller than the size of the rolling elements (1, 2) to such a degree that the rubber coating (13, 14) around the mounted rolling elements (1, 2) is elastically deformed. Rolling element bearing according to Claim 1, characterized by the fact that the thickness of the rubber coating (13, 14) is 0.5 to 0.05 times the thickness of the material of the bearing cage. Rolling element bearing according to one of the preceding claims, characterized by the fact that the rubber coating (13, 14) is reinforced with a mesh, fabric or strong fibers.

Inventors: JACOBSON, BO OLOV
Applicants: SKF INDUSTRIAL TRADING & DEVELOPMENT CO, B.V.
Application year: 1989
Main classification: F16C33
IPC codes: F16C33