JP4025595B2 - Plastic cage for rolling bearing and rolling bearing having the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plastic cage for a rolling bearing formed so as to be manufactured by injection molding and a rolling bearing having the same.
[0002]
[Prior art]
Such a cage is already known from German Utility Model Registration No. 1886747. This known cage has a plurality of crosspieces forming pockets for accommodating rolling elements, and these crosspieces are connected to each other at both ends by both side wheels. The radial dimension of the side ring of this cage is half the radial dimension of the crosspiece. The one side wheel extends from the cage inner diameter to the center of the cross piece cross section, and the opposite side wheel extends from the center of the cross piece cross section to the cage outer diameter. The known cage is specifically designed for easy assembly.
[0003]
However, in the case of plastic cages, in addition to assembly problems, it has become clear that there are problems with the durability of the cages, especially under adverse operating conditions.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a plastic cage that is durable and not damaged even under adverse operating conditions.
[0005]
[Means for Solving the Problems and Effects of the Invention]
The object of the present invention is solved by the means described in claim 1.
[0006]
The plastic cage according to the present invention has both side wheels axially spaced from each other. The both side wheels are connected to each other by a plurality of cross pieces extending in the axial direction. These crosspieces are distributed over the circumference of the side wheels so as to form pockets for accommodating rolling elements together with the side wheels on both sides. Both side wheels have different diameters so that the plastic cage can be manufactured with a tool that can move axially during injection molding, and the inner diameter of one side wheel is the other side. It is formed more than the outer diameter of the side wheel . Each of the crosspieces protrudes radially outward from both side wheels, and has a first guide surface facing radially outward for a cage to be guided by a radially facing flange provided on the outer ring of the rolling bearing. Have.
[0007]
The plastic cage according to the present invention does not require a tool that moves in the radial direction when forming by injection molding, and thus has an advantage that it can be manufactured at low cost.
[0008]
Another advantage of the present invention is that it is mechanically very strong because the crosspiece has a large radial dimension extending beyond the side wheels. The free space formed by the radially projecting portion of the crosspiece from the side wheel and the outer peripheral surface of the side wheel has the advantage that the lubricant can be transported very well in the axial direction.
[0009]
In an advantageous embodiment of the plastic cage according to the invention, the crosspieces are arranged on the mutually facing surfaces of the adjacent crosspieces in order to assist the plastic cage with the rolling elements. It has a guide surface. The resulting composite guide gives the plastic cage according to the invention great mechanical strength and durability against radial vibrations.
[0010]
The second guide surface is preferably formed such that the rolling element rolls in contact with the second guide surface on the radially outer side of a circle connecting the rolling element centers. This advantageously allows the cross piece to be very thick and therefore mechanically strong.
[0011]
Planar depressions are provided on mutually facing surfaces of crosspieces adjacent to each other. In it, dirt particles accumulate, which keeps the dirt particles particularly away from the first and second guide surfaces. In particular, this prevents the formation of grooves on the outer peripheral surface of the rolling element. The recess has a depth of at most 0.3 mm so that a plastic cage produced by injection molding can be punched without problems.
[0012]
Furthermore, a protrusion disposed at the center in the axial direction is provided on the surfaces of the crosspieces adjacent to each other in order to prevent the rolling elements from falling off. The central arrangement of the projections makes it possible to maintain a radial free space between the projections and the side wheels in the range of the side wheels in the axial direction and thus increase the flexibility of the plastic cage.
[0013]
The crosspiece is provided with a recess in the first guide surface in order to reduce the mass of the plastic cage according to the invention and to optimize the flow of injection molding material during the production of the cage.
[0014]
The transition range between each side wheel and the crosspiece is individually rounded to reduce stress.
[0015]
The surfaces facing each other in the axial direction of the both side wheels are curved in a convex shape in the range between the adjacent cross pieces in order to reduce wear of the rolling elements rolling in contact therewith.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings.
[0017]
In FIG. 1, FIG. 2, and FIG. 3, only a part of the plastic cage protruding in the radial direction at regular intervals in the circumferential direction is shown for easy understanding. As can be seen from these figures, the plastic cage has two side wheels 1, 2 that are axially spaced from each other. The both side wheels 1 and 2 are connected to each other by a plurality of cross pieces 3 extending in the axial direction. These crosspieces 3 are distributed over the circumference of the side wheels 1 and 2 so as to form pockets 4 for accommodating the rolling elements 5 together with the side wheels 1 and 2 on both sides. The two side wheels 1 and 2 have different diameters so that the plastic cage can be manufactured with a tool that can move in the axial direction during injection molding. In other words, the inner diameter of the one-side wheel 1 is set to be larger than the outer diameter of the opposite-side wheel 2 so that there is no overlap between the both-side wheels 1 and 2 when viewed in the axial direction.
[0018]
Each of the plurality of crosspieces 3 has a first guide surface 6 that protrudes radially outward from both side wheels 1 and 2 and faces outward in the radial direction for guiding the cage by the bearing race. The radial space between the first guide surface 6 and the outer diameters of the two side wheels 1 and 2 formed by the protrusions of the cross piece 3 from the two side wheels 1 and 2 is good in the axial direction of the lubricant. Allows to flow into. In this connection, in order to ensure a sufficient flow of the lubricant, when the plastic cage is dimensioned, it is desirable that the projecting dimension of the cross piece 3 from the both side wheels 1 and 2 is at least 2 mm.
[0019]
The crosspieces 3 adjacent to each other have second guide surfaces 7 for assisting the plastic cage by the rolling elements 5 on the surfaces facing each other in the circumferential direction. The second guide surface 7 is formed such that the rolling element 5 rolls in contact with the second guide surface 7 on the radially outer side of a circle 9 connecting the plurality of rolling element centers 8. Therefore, in the illustrated embodiment, the first guide surface 6 and the second guide surface 7 are involved to perform composite guidance. The involvement of the second guide surface 7 is optional and can be omitted, but this serves to stabilize as a whole.
[0020]
A planar recess 10 is further formed on the surface of the crosspiece 3 where the second guide surface 7 exists. In this recess 10, dirt particles are deposited. As a result, the dirt particles do not reach the second guide surface 7 and therefore do not reach the first guide surface 6, whereby the first and second guide surfaces 6, 7 or their guides due to the dirt particles. Damage or severe wear on the opposing surfaces in contact with surfaces 6 and 7 is avoided. In order to be able to die the plastic cage after injection molding, the indentation 10 is formed very shallow, resulting in only a few undercuts that can be overcome without damaging the plastic cage. Absent. It has been confirmed that the above-described characteristics of the recess 10 are obtained when the depth is a maximum of 0.3 mm.
[0021]
Opposite sides of the crosspieces 3 adjacent to each other have protrusions 11 that prevent the rolling elements 5 from falling off in the vicinity of the inner peripheral edge thereof. As a result, the movement of the rolling element 5 inward in the radial direction is restricted, that is, the rolling element is prevented from falling off, so that the assembly of the cage equipped with the rolling element is facilitated. The protrusion 11 is preferably arranged at the center in the axial direction and does not extend completely to the side wheels 1 and 2 so that a gap 12 exists. This increases the flexibility of the plastic cage and makes the assembly easier than in the case where the protrusion 11 is firmly coupled to the side wheels 1 and 2.
[0022]
The cross piece 3 has a radial recess 13 extending in the axial direction in the range of the first guide surface 6. The recess 13 is open toward at least one axial side of the crosspiece 3 in order to allow for die cutting in the axial direction.
[0023]
The transition ranges 14 between the side wheels 1, 2 and the crosspiece 3 are each rounded in order to reduce the stress concentration in this range.
[0024]
The surfaces 15 facing each other in the axial direction of the two side wheels 1 and 2 that limit the axial play of the rolling element 5 are curved in a convex shape in the range between the adjacent cross pieces 3. As a result, wear on the end face of the rolling element 5 that rolls in contact therewith is reduced.
[0025]
The rolling element 5 rolls between the inner ring 16 and the outer ring 17. The outer ring 17 has flanges 18 facing inward in the radial direction on both axial sides thereof. The first guide surface 6 of the cross piece 3 is in contact with and slides on the radially inward surfaces 19 of the flanges 18.
[0026]
The plastic cage is assembled and surrounded by a lubricant, in particular grease. This grease is applied especially to the first guide surface 6 and the second guide surface 7 in order to minimize the wear in these ranges.
[Brief description of the drawings]
FIG. 1 is a partial perspective view of a plastic cage according to the present invention.
FIG. 2 is a partial sectional view of a plastic cage according to the present invention.
FIG. 3 is a partial perspective view of a plastic cage according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Side wheel 2 Side wheel 3 Crosspiece 4 Pocket 5 Rolling body 6 1st guide surface 7 2nd guide surface 8 Rolling body center 9 Circle 10 Depression 11 Protrusion 12 Crevice 13 Recess 14 Transition range 15 Surface 16 which faced the axial direction Inner ring 17 Outer ring 18 Flange

Claims (11)

Both side wheels ( 1, 2 ) spaced apart from each other in the axial direction and a plurality of cross pieces ( 3 ) extending in the axial direction for joining the two side wheels ( 1, 2, 2 ) to each other. (3), so as to form a pocket (4) for accommodating the rolling elements (5) with sides side wheels (1, 2) are arranged distributed over the circumference of the side wheels (1, 2), both sides Plastic cages for rolling bearings whose side rings ( 1, 2 ) have different diameters so that the plastic cages can be manufactured with tools that can move axially during injection molding , The inner diameter of the side wheel (1) on one side is formed to be greater than the outer diameter of the side wheel (2) on the other side, and the crosspieces ( 3 ) are respectively connected to both side wheels ( 1,2 ). provided on the outer ring (17) of the projecting rolling bearing radially outward Plastic cage for a rolling bearing, characterized in that the retainer has a first guide surface (6) facing radially outward for being guided by the flange (18) facing radially inward . 2. The plastic cage according to claim 1, wherein the cross piece ( 3 ) protrudes at least 2 mm in the radial direction from both side wheels ( 1, 2 ) . The crosspiece ( 3 ) has second guide surfaces ( 7 ) arranged on mutually facing surfaces of the crosspieces ( 3 ) adjacent to each other in order to assist the plastic cage by the rolling elements ( 5 ) . The plastic cage according to any one of claims 1 to 3, wherein the plastic cage is provided. The second guide surface ( 7 ) is formed so that the rolling element ( 5 ) rolls in contact with the second guide surface ( 7 ) on the radially outer side of the circle ( 9 ) connecting the plurality of rolling element centers ( 8 ). The plastic retainer according to claim 3, wherein the retainer is made of plastic. 5. The crosspiece ( 3 ) according to claim 1, wherein the mutually facing surfaces of the crosspieces ( 3 ) adjacent to each other have a planar depression ( 10 ). Plastic cage. 6. A plastic cage as claimed in claim 5, wherein the indentation ( 10 ) has a maximum depth of 0.3 mm. The cross piece ( 3 ) has a protrusion ( 11 ) arranged at the axial center in order to prevent the rolling elements ( 5 ) from dropping off on the mutually facing surfaces of the adjacent cross pieces ( 3 ) . The plastic cage according to any one of claims 1 to 6. The plastic cage according to any one of claims 1 to 7, wherein the cross piece ( 3 ) has a recess ( 13 ) in the first guide surface ( 6 ) . 9. The transition range ( 14 ) between each side wheel ( 1,2 ) and the crosspiece ( 3 ) , respectively, is rounded, according to any one of claims 1-8. Plastic cage. The surfaces ( 15 ) facing each other in the axial direction of both side wheels ( 1, 2 ) are curved in a convex shape in a range between adjacent crosspieces ( 3 ) . The plastic cage according to any one of the above. An inner ring (16), an outer ring (17), in rolling bearing and a rolling element disposed between the inner and outer wheels (16, 17) (5), rolling elements (5), according to claim 1 or claim A rolling bearing, wherein the rolling bearing is disposed in the plastic cage according to any one of 10.

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