Rolling bearing cage and method for manufacturing a rolling bearing cage

Abstract

The invention is based on a rolling bearing cage with at least one first end face (10). It is proposed that the first end face has at least one elevation (12) which differs from a single step which has a right angle in a section.

Description

[0001] The invention relates to a rolling bearing cage and a method for manufacturing the rolling bearing cage.

[0002] A rolling bearing cage with at least one first end face is known. The rolling bearing cage is made of brass. Furthermore, a rolling bearing cage made of PEEK with glass fiber reinforcement is known.

[0003] The object of the invention is, in particular, to achieve high efficiency. This object is achieved according to the invention by the features of claim 1 and by the features of claim 9, while advantageous embodiments and further developments of the invention can be found in the dependent claims.

[0004] The invention is based on a rolling bearing cage with at least one first end face.

[0005] It is proposed that the first end face have at least one raised section that differs from a single step, which has a right angle in a cross-section. The phrase "the step has a right angle in a cross-section" is understood to mean, in particular, that there is a plane such that a cross-sectional surface between the plane and the step has a contour with a right angle. This allows for high efficiency.In particular, it can be achieved that, despite a depression in a pocket-side surface of a ring segment of the rolling bearing cage, the ring segment has an approximately constant axial thickness along a circumferential direction of the rolling bearing cage, so that when the rolling bearing cage is manufactured by injection molding from a glass fiber reinforced plastic, a uniform flow of the glass fiber reinforced plastic can be achieved, whereby a large quantity of glass fibers in the finished rolling bearing cage experience a favorable, especially extended, alignment and thus contribute to a high resistance of the cage.

[0006] In particular, the elevation can be at least partially stepped.

[0007] Advantageously, the increase with respect to a circumferential direction of the rolling bearing cage is arranged between a center of mass of a ring segment of the rolling bearing cage, which exactly limits a pocket of the rolling bearing cage with respect to an axial direction of the rolling bearing cage, and a center of mass of a web of the rolling bearing cage, which limits the pocket with respect to the circumferential direction.The phrase "between" the center of mass of a ring segment and the center of mass of a web of the bearing cage, with respect to a circumferential direction of the rolling bearing cage, is to be understood in particular as meaning that the raised section is arranged between a first half-plane and a second half-plane, both of which are bounded by a straight line extending axially through the rolling bearing cage and through a center of mass of the rolling bearing cage. The first half-plane has the center of mass of the ring segment, and the second half-plane has the center of mass of the web. This allows for a stable design of the rolling bearing cage and a long service life. In particular, when manufactured by injection molding with a glass fiber reinforced plastic, an extended arrangement of many glass fibers can be achieved, resulting in high stability.In particular, a corner area of ​​a pocket of the rolling bearing cage, which is closest to the elevation, can be designed to be recessed compared to a boundary surface of the pocket surrounding the corner area, so that during an operating process a rolling element moving in the pocket does not collide with the corner area and thereby wear it out disproportionately.

[0008] Furthermore, it is proposed that the raised section along a circumferential direction of the bearing cage be free of steps with a height such that the height divided by the maximum axial extension length of a ring segment of the bearing cage containing the raised section, extending between two axial webs of the bearing cage that define the same pocket, is greater than 0.1724. This allows for a stable design. In particular, when manufactured by injection molding with a glass fiber reinforced plastic, an extended arrangement of many glass fibers can be achieved, resulting in high stability. Furthermore, injection molding allows for uniform cooling after injection molding, largely preventing cracking.

[0009] Advantageously, the raised section forms part of a ring segment of the rolling bearing cage, extending from a first axial web of the rolling bearing cage to a second axial web of the rolling bearing cage, wherein the ring segment, the first web, and the second web define the same pocket of the rolling bearing cage. The maximum axial extension length of the ring segment at a point where the raised section is highest, divided by the maximum axial extension length of the ring segment, deviates from 0.816 by no more than fifteen percent, preferably by no more than ten percent, and particularly preferably by no more than five percent. This allows for higher stability or strength than in known injection-molded cages according to the current state of the art.In particular, when manufacturing by injection molding with a glass fiber reinforced plastic, an extended arrangement of many glass fibers can be achieved, resulting in high stability.

[0010] In an advantageous embodiment of the invention, the first end face has at least one corrugated sub-surface, which is partially formed by a surface of the raised section and which is free of steps having a height such that the height, divided by the maximum axial extension length of a ring segment of the bearing cage having the raised section, which extends between two axial webs of the bearing cage that define the same pocket of the bearing cage, is greater than 0.1724. This allows for a stable design. In particular, when manufactured by injection molding with a glass fiber reinforced plastic, an extended arrangement of many glass fibers can be achieved, resulting in high stability. Furthermore, uniform cooling after injection molding can be achieved when manufacturing by injection molding.

[0011] In particular, the corrugated surface can have multiple crests and troughs. Specifically, the corrugated surface can extend 360° around a central axis of the bearing cage extending axially along a circumferential direction.

[0012] Furthermore, it is proposed that the rolling bearing cage have at least one boundary surface of a pocket of the rolling bearing cage, which forms a complete boundary of the pocket with respect to an axial direction of the rolling bearing cage and which has a first and a second end with respect to a circumferential direction of the cage, wherein the boundary surface has a surface area spaced from the ends which projects further into the pocket in a direction opposite to the axial direction than the two ends. This allows for a long service life. In particular, it ensures that the two ends of a rolling element moving in the pocket are not subjected to disproportionate wear during operation.

[0013] Advantageously, the rolling bearing cage has at least one pocket which is completely bounded by a boundary surface of the rolling bearing cage, wherein the boundary surface is free of steps having a height such that the height divided by the maximum axial extension length of a ring segment of the rolling bearing cage having the raised section, which extends between two axial webs of the rolling bearing cage that define the pocket, is greater than 0.1724. This allows for a stable design. In particular, when manufactured by injection molding with a glass fiber reinforced plastic, an extended arrangement of many glass fibers can be achieved, resulting in high stability. Furthermore, slow cooling after injection molding can be achieved when manufacturing by injection molding.

[0014] In particular, the boundary surface can be continuously differentiable in the mathematical sense.

[0015] In an advantageous embodiment of the invention, the rolling bearing cage consists at least partially of glass fiber reinforced injection-molded plastic or of aluminum. The term "injection-molded plastic" is understood to mean, in particular, a plastic with which objects can be manufactured by injection molding. This allows for high stability at a low weight.

[0016] In particular, the injection-molded plastic can be polyamide or PEEK. Specifically, the glass fiber-reinforced injection-molded plastic can have a glass fiber content of between 15 and 20 percent by weight.

[0017] Furthermore, a method for manufacturing a rolling bearing cage, in particular a rolling bearing cage as described above, is proposed, in which the rolling bearing cage is manufactured by injection molding, wherein, viewed in the circumferential direction of an injection mold of the rolling bearing cage, injection occurs at every second web of the rolling bearing cage. This allows for high efficiency. In particular, when using glass fiber-reinforced injection molding plastic, weld lines can be ensured only at locations of the rolling bearing cage that are subject to relatively low loads.

[0018] In particular, the webs at which injection takes place can have a main extension direction which is parallel to an axial direction of the rolling bearing cage.

[0019] Advantageously, the injection mold consists of at least three mold parts, and a section of the rolling bearing cage produced by a first set of mold parts has a smaller maximum diameter than the sections produced by the other two mold parts. This prevents the first mold part from creating a cage section that protrudes radially compared to the sections produced by the other two mold parts due to an offset relative to the first mold part.

[0020] Further advantages will become apparent from the following description of the drawings. The drawings illustrate an embodiment of the invention. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations. Fig. Figure 1 shows a perspective view of a rolling bearing cage according to the invention, Fig. Figure 2 shows another perspective view of the roller bearing cage, Fig. Figure 3 shows a top view of part of the rolling bearing cage with a pocket from the radial outside, Fig. 4 shows a cross-section through the pocket with the orientation of the fiber optic cable, and Fig. Figure 5 shows a view of the rolling bearing cage in its axial direction. Fig. Figure 1 shows a rolling bearing cage according to the invention with a first end face 10, which has a raised section 12. The rolling bearing cage consists of three sections 44, 46, 48. Section 48 is annular and has the first end face 10. Section 46 is identical in construction to section 48. Section 46 and section 48 are connected and fastened to each other by section 44. Section 46 and section 48, together with a first web 26 extending mainly in the axial direction 22 of the rolling bearing cage and a second web 27 extending mainly in the axial direction 22, define a pocket 20 of the cage ( Fig. 1 and Fig. 3) Footbridges 26 and 27 are identical in construction. Furthermore, area 44 consists of footbridges 26 and 27 and other footbridges that are identical in construction to footbridge 26. Area 44 also has an even number of footbridges.

[0021] The raised section 12 differs from a single step, which has a right angle in a cross-section. Furthermore, the raised section 12 is free of steps along a circumferential direction 14 of the rolling bearing cage, which has a height such that the height divided by a maximum axial extension length 28 of a ring segment 18 of the rolling bearing cage containing the raised section, which extends only between the webs 26, 27, is greater than 0.1724. The raised section 12 is also located with respect to the circumferential direction 14 between a center of mass 16 of the ring segment 18, which delimits the pocket 20 with respect to the axial direction 22, and a center of mass 24 of the web 26, which delimits the pocket with respect to the circumferential direction.

[0022] Furthermore, the maximum axial extension length 29 of the ring segment, at a point on the ring segment where the elevation is highest, deviates by a maximum axial extension length 28 of the ring segment by no more than fifteen percent from 0.816. The first end face 10 has at least one corrugated sub-surface 32, which is partially formed by a surface 34 of the elevation 12 and which is free of steps having a height such that the height, divided by the maximum axial extension length 28 of the ring segment 18, is greater than 0.1724. The corrugated sub-surface 32 has a plurality of wave crests, one of which is the elevation 12, and a plurality of wave troughs along the circumferential direction 14 over the entire circumference of the rolling bearing cage. In this case, the area 48 has two elevations per pocket, which are shaped like the elevation 12 or as its mirror image.A further raised section 50 extends across the entire circumference of the rolling bearing cage and is located centrally on the end face 10 with respect to a radial direction of the rolling bearing cage. The raised section 12 is located radially outside the raised section 50. Radially inside the raised section 12 and the raised section 50 is a further raised section 52 of the end face 10, which has a slightly different height than the raised section 12. At each corner of a pocket of the cage, the end face has raised sections that are identical in design to the raised sections 12 and 52 or are mirror images of them. Furthermore, at each point where a web meets an axial end face of the region 48, which is located opposite the end face 10, the end face 10 has a raised section 54 that has a circular outline in a top view of the end face 10.Adjacent to the locations of the elevations 54, pins are arranged in the case of the manufacture of the rolling bearing cage by injection molding using an injection mold, which ensure venting during injection molding and which allow the removal of the area 48 from the injection mold after injection molding.

[0023] The front surface 10 is, in a mathematical sense, continuously differentiable overall.

[0024] The rolling bearing cage has a boundary surface 36 of the pocket 20, which forms a complete boundary of the pocket 20 with respect to the axial direction 22 of the rolling bearing cage and which has a first and a second end 38, 39 with respect to the circumferential direction 14 of the rolling bearing cage. The boundary surface 36 has a surface area 40 spaced from the ends, which projects further into the pocket 20 in a direction opposite to the axial direction than the two ends. Similarly, middle areas of the webs 26, 27 project further into the pocket 20 than axial end areas of the webs 26, 27. Overall, this prevents contact between a rolling element located in the pocket during operation and the corners of the pocket, thus increasing the service life of the rolling bearing cage.

[0025] Furthermore, the rolling bearing cage has a wave-shaped surface 42, which completely borders the pocket 20. The boundary surface 36 and the surface area 40 are part of the wave-shaped surface 42. The wave-shaped surface 42 is free of edges and therefore continuously differentiable in the mathematical sense. In particular, the wave-shaped surface 42 is thus free of steps.

[0026] The rolling bearing cage is made of glass fiber reinforced polyetheretherketone (abbreviated PEEK). The glass fiber content ranges from 5 to 80 percent by weight, advantageously from 15 to 20 percent by weight. Alternatively, the rolling bearing cage can be made of aluminum or other materials that can be injection molded.

[0027] In a method for manufacturing the rolling bearing cage, injection occurs axially at the center of every second web 26 simultaneously and with the same volume flow rate, in the circumferential direction 14 of the rolling bearing cage and thus in the circumferential direction of the injection mold. This results in a weld line being formed axially at the center of those webs where no injection takes place. This is advantageous because the load at these locations is comparatively low. A planar section through the pocket 20 is shown in Fig. Figure 4 illustrates this. The injection method and the geometry of the rolling bearing cage result in improved flow with minimal turbulence, and in the finished state, the resulting alignment of the glass fibers (Figure 4) contributes to the robustness of the cages during operation. These areas of high load are primarily the corners of the cage pockets. This is shown in Fig. Figure 4 illustrates this, with the glass fibers shown in white. A high density of extended glass fibers also results in high stability.

[0028] The injection mold consists of at least three mold parts. A region 44 of the rolling bearing cage, which is produced by a first set of mold parts, has a smaller maximum diameter than those regions 46, 48, which are produced by those mold parts that do not belong to the first set.

[0029] Fig. Figure 2 shows another perspective view of the rolling bearing cage, in which a second end face of the cage is visible. Furthermore, Figure 2 shows... Fig. 5 a view of the rolling bearing cage in axial direction.

[0030] The roller bearing cage is a single, one-piece design. It is lightweight and contains no environmentally or health-damaging materials.

[0031] Due to its material and geometry, the rolling bearing cage exhibits optimized friction and wear characteristics. Furthermore, the cage ages slowly under elevated temperatures, which is important because the cage's service life is often crucial for the service life of the bearing in which it is installed, as the cage fulfills two important functions: guiding and separating the rolling elements. Because of the reduced friction during operation, comparatively little heat is generated, thus also slowing the aging of the bearing lubricant. The rolling bearing cage also exhibits high compatibility with aggressive media. Examples of such aggressive media include sour gases, chlorine gas, sulfur gases, acids, bases, and ammonia. This makes the rolling bearing cage particularly well-suited for applications in gas-fired power plants. Finally, the cage is comparatively lightweight.The cage also meets high demands in terms of high rotational speeds, sustainability, and high strength. Furthermore, the cage can be manufactured efficiently.

[0032] The increase of 50 provides a good reference for determining the dimensions of the cage. Reference symbol list: 10 Front surface 12 Increase 14 Circumferential direction 16 Center of Mass 18 ring segment 20 bags 22 Axial direction 24 Center of Mass 26 Bridge 27 Bridge 28 Extension length 29 Extension length 32 partial area 34 surface 36 Border area 38 End 39 End 40 area 42 Border area 44 area 46 area 48 area 50 increase 52 increase 54 increase

Claims

[1] Rolling bearing cage with at least one first end face (10), characterized by , that the first end face has at least one elevation (12) which differs from a single step which has a right angle in a section. [2] Rolling bearing cage according to claim 1, characterized by , that the elevation (12) is arranged with respect to a circumferential direction (14) of the rolling bearing cage between a center of mass (16) of a ring segment (18) of the rolling bearing cage, which exactly defines a pocket (20) of the rolling bearing cage with respect to an axial direction (22) of the rolling bearing cage, and a center of mass (24) of a web (26) of the rolling bearing cage, which defines the pocket with respect to the circumferential direction. [3] Rolling bearing cage according to claim 1 or claim 2, characterized by, that the elevation (12) along a circumferential direction (14) of the rolling bearing cage is free of steps which have a height such that the height divided by a maximum axial extension length (28) of a ring segment (18) of the rolling bearing cage having the elevation, which extends between two axial webs (26, 27) of the rolling bearing cage which define the same pocket (20) of the rolling bearing cage, is greater than 0.1724. [4] Rolling bearing cage according to at least one of the preceding claims, characterized by, that the elevation (12) is part of a ring segment (18) of the rolling bearing cage, which extends from a first axial web (26) of the rolling bearing cage to a second axial web (27) of the rolling bearing cage, wherein the ring segment, the first web and the second web define the same pocket (20) of the rolling bearing cage and a maximum axial extension length (29) of the ring segment at a point of the ring segment where the elevation is highest, divided by a maximum axial extension length (28) of the ring segment, deviates by no more than fifteen percent from 0.

816. [5] Rolling bearing cage according to at least one of the preceding claims, characterized by, that the first end face (10) has at least one undulating partial surface (32) which is partially formed by a surface (34) of the elevation (12) and which is free of steps having a height such that the height divided by a maximum axial extension length (28) of a ring segment (18) of the bearing cage having the elevation, which extends between two axial webs (26, 27) of the bearing cage bounding the same pocket (20) of the bearing cage, is greater than 0.1724. [6] Rolling bearing cage according to at least one of the preceding claims, characterized byat least one boundary surface (36) of a pocket (20) of the rolling bearing cage, which forms a complete boundary of the pocket with respect to an axial direction (22) of the rolling bearing cage and which has a first and a second end (38, 39) with respect to a circumferential direction (14) of the rolling bearing cage, wherein the boundary surface has a surface area (40) spaced apart from the ends, which projects further into the pocket in a direction opposite to the axial direction than the two ends. [7] Rolling bearing cage according to any of the preceding claims, characterized byat least one pocket (20) which is completely bounded by a boundary surface (42) of the rolling bearing cage, wherein the boundary surface is free of steps which have a height such that the height divided by a maximum axial extension length (28) of a ring segment (18) of the rolling bearing cage having the elevation, which extends between two axial webs (26, 27) of the rolling bearing cage bounding the pocket, is greater than 0.1724. [8] Rolling bearing cage according to any of the preceding claims, characterized by that the roller bearing cage is at least partially made of glass fiber reinforced injection-molded plastic or aluminum. [9] Method for manufacturing a rolling bearing cage, in particular a rolling bearing cage according to at least one of claims 1 to 8, in which the rolling bearing cage is manufactured by injection molding, wherein, viewed in the circumferential direction (14) of an injection mold of the rolling bearing cage, injection is carried out at every second web (26) of the rolling bearing cage. [10] Method according to claim 9, characterized by , that the injection mold consists of at least three mold parts and that a region (44) of the rolling bearing cage produced by a first set of mold parts has a smaller maximum diameter than those regions (46, 48) produced by those mold parts that do not belong to the first set.

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