CN115126779A - Resin retainer - Google Patents
Resin retainer Download PDFInfo
- Publication number
- CN115126779A CN115126779A CN202210277688.2A CN202210277688A CN115126779A CN 115126779 A CN115126779 A CN 115126779A CN 202210277688 A CN202210277688 A CN 202210277688A CN 115126779 A CN115126779 A CN 115126779A
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- China
- Prior art keywords
- resin
- crown
- shaped resin
- holder
- fatigue limit
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- 229920005989 resin Polymers 0.000 title claims abstract description 226
- 239000011347 resin Substances 0.000 title claims abstract description 226
- 238000005096 rolling process Methods 0.000 claims description 26
- 229920003002 synthetic resin Polymers 0.000 claims description 8
- 239000000057 synthetic resin Substances 0.000 claims description 8
- 239000004952 Polyamide Substances 0.000 claims description 6
- 229920002647 polyamide Polymers 0.000 claims description 6
- 210000000078 claw Anatomy 0.000 description 7
- 229920000049 Carbon (fiber) Polymers 0.000 description 6
- 239000004917 carbon fiber Substances 0.000 description 6
- 239000003365 glass fiber Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 238000009661 fatigue test Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000001746 injection moulding Methods 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 229920003189 Nylon 4,6 Polymers 0.000 description 1
- 229920002302 Nylon 6,6 Polymers 0.000 description 1
- 229920012310 Polyamide 9T (PA9T) Polymers 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000005489 elastic deformation Effects 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 238000012886 linear function Methods 0.000 description 1
- 239000010687 lubricating oil Substances 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012779 reinforcing material Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/30—Parts of ball or roller bearings
- F16C33/38—Ball cages
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/30—Parts of ball or roller bearings
- F16C33/38—Ball cages
- F16C33/44—Selection of substances
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Rolling Contact Bearings (AREA)
Abstract
The invention provides a resin retainer which does not protrude from the axial side surface of a deep groove ball bearing and has a strength equal to or higher than a fatigue limit (U) within a range of a maximum load applied to the resin retainer. The thickness (t) of the crown-shaped resin cage (5) in the axial direction of the portion of the pocket (5a) that holds the balls (4) is set so that the stress generated in the portion of the crown-shaped resin cage (5) having the smallest axial cross-sectional area when a predetermined maximum load (F) is applied to the crown-shaped resin cage is less than the fatigue limit (U) of the crown-shaped resin cage (5) and the crown-shaped resin cage (5) is located inside the axial width (B) of the deep groove ball bearing (1).
Description
Technical Field
The present invention relates to a resin holder.
Background
Conventionally, there is known a resin cage for a deep groove ball bearing manufactured by injection molding (injection molding). The resin holder is formed by injection molding using a mold having a corresponding annular cavity formed therein, for example. The molten resin injected into the cavity is separated and merged by moving in the cavity. The molten resins in the cavities are joined to each other in a confluent state and solidified, thereby forming a weld.
On the other hand, in the deep groove ball bearing in which the rolling elements are held by the resin cage, relative movement (advance/retard of the rolling elements) with respect to the cage of the rolling elements is generated due to a difference between the revolving speed of the rolling elements and the revolving speed of the resin cage. The pocket portion of the resin cage repeatedly collides with the rolling elements during rotation of the deep groove ball bearing due to relative movement of the rolling elements and the resin cage. The resin cage repeats elastic deformation due to collision with the rolling elements. That is, in the resin cage, repeated stress is generated due to collision with the rolling elements. In the resin holder, repeated stress concentrates on the welded portion, and therefore is disadvantageous in terms of affecting the fatigue life. Therefore, a resin cage is known which improves the joint strength of the welded portion to suppress the influence on the fatigue life of the resin cage. For example, as described in patent document 1.
Documents of the prior art
Patent document
Patent document 1: japanese laid-open patent publication No. 2020-026856
Disclosure of Invention
Technical problem to be solved by the invention
The mold for forming the resin holder described in patent document 1 is configured such that the opening area of the resin reservoir connected to the cavity is larger than the opening area of the resin ejection hole connected to the cavity. Thus, the molten resin filled in the cavity flows smoothly into the resin reservoir without being retained in the resin reservoir. As a result, convection of the molten resin occurs in the cavity after the weld portion is formed, and the contact area between the molten resins increases due to deformation of the weld portion. Thus, even when a resin material having a relatively high melt viscosity is used, the strength of the welded portion of the resin retainer can be increased. However, in the technique described in patent document 1, the deformation state of the welded portion in the cavity cannot be grasped. That is, it is not clear whether or not the strength of the welded portion in the resin holder is equal to or higher than the fatigue limit. Therefore, the resin holder needs to be designed based on a large safety rate beyond necessity in such a manner that the resin holder has a strength above the fatigue limit within the range of the maximum load applied to the resin holder, which is disadvantageous in this respect.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a resin retainer which does not protrude from an axial side surface of a deep groove ball bearing and has a strength equal to or higher than a fatigue limit in a range of a maximum load applied to the resin retainer.
Means for solving the problems
That is, the first invention is a resin cage that holds a plurality of rolling elements of a deep groove ball bearing at equal intervals. In the resin cage, the width in the axial direction of the portion where the cross-sectional area in the axial direction of the pocket portion holding the rolling element is smallest is included in a range calculated by equation (1) such that, when a predetermined maximum load is applied to the resin cage, the stress generated in the portion where the cross-sectional area in the axial direction is smallest is lower than the fatigue limit of the resin cage and the resin cage is located in a range inside the width in the axial direction of the deep groove ball bearing,
[ formula 1]
F: maximum load applied to the resin holder, U: fatigue limit of resin constituting the resin holder, α: a reduction rate of fatigue limit by a welded portion of the resin holder, Da: diameter of rolling element, t: the axial thickness of the minimum cross-sectional area, B: the axial width of the deep groove ball bearing.
In a second aspect of the present invention, the resin forming the resin holder is a polyamide synthetic resin.
In a third aspect of the present invention, the resin forming the resin holder includes a fiber-reinforced resin.
In a fourth aspect of the present invention, a reduction rate of a rate of reduction of the fatigue limit of the resin constituting the resin holder by the welded portion is 0.6 or more and 0.8 or less.
Effects of the invention
As the effects of the present invention, the following effects can be achieved.
That is, the first invention is set such that the shape of the portion of the resin holder where the cross-sectional area in the axial direction of the pocket portion that is considered to generate the maximum stress is the smallest satisfies expression (1). The resin cage assembled in the deep groove ball bearing has a radial width not contacting with the inner ring and the outer ring of the deep groove ball bearing, and has an axial thickness in which a stress generated in a portion having a smallest cross-sectional area in the axial direction is lower than a fatigue limit of a resin constituting the resin cage when an assumed maximum load of the resin cage is applied to the resin cage. In addition, the formula (1) includes a reduction rate of the fatigue limit due to the welded portion. Therefore, even when a welded portion is present in the portion of the resin holder having the smallest axial cross-sectional area, the stress generated in the portion of the resin holder having the smallest axial cross-sectional area is lower than the fatigue limit of the resin constituting the resin holder. Further, the resin cage assembled into the deep groove ball bearing has a thickness not protruding from the axial side surfaces of the inner ring and the outer ring. This makes it possible to provide the resin cage with strength equal to or higher than the fatigue limit within the range of the maximum load applied to the resin cage without protruding from the axial side surface of the deep groove ball bearing.
The second and third aspects of the present invention can improve the fatigue limit of the crown-shaped resin holder by forming the crown-shaped resin holder from a polyamide synthetic resin having excellent toughness, impact resistance, and flexibility, or by using a fiber-reinforced resin containing Glass Fibers (GF), Carbon Fibers (CF), or the like. Thus, the crown-shaped resin cage can be expanded in the range of thickness in the axial direction required for the strength equal to or higher than the fatigue limit within the range of the maximum load applied to the resin cage without protruding from the axial side surface of the deep groove ball bearing.
In the fourth aspect of the invention, by taking into account a reduction rate of a fatigue limit due to the welded portion of the resin holder, even if the portion having the smallest cross-sectional area in the axial direction has the welded portion, a stress generated at the welded portion when an assumed maximum load of the holder is applied to the resin holder is lower than the fatigue limit of the resin forming the resin holder. Thus, the crown-shaped resin cage can have a strength equal to or higher than the fatigue limit within the range of the maximum load applied to the resin cage without protruding from the axial side surface of the deep groove ball bearing.
Drawings
Fig. 1 is a sectional view of a deep groove ball bearing.
Fig. 2 is a side view of a crown-shaped resin retainer according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of a load state due to advance and retard of the rolling elements with respect to the crown-shaped resin cage relating to the embodiment of the present invention.
Fig. 4 is a graph showing a relationship between a load and a rolling element diameter under predetermined conditions in the crown-shaped resin cage according to the embodiment of the present invention.
Fig. 5 is a schematic diagram of a fatigue test of a crown-shaped resin holder of the embodiment of the present invention.
Fig. 6 is a graph showing the relationship between the radial thickness of the crown-shaped resin cage and the diameter of the rolling element according to the embodiment of the present invention.
Detailed Description
A deep groove ball bearing 1 as an embodiment of the deep groove ball bearing of the present invention will be described with reference to fig. 1 and 2. Fig. 1 is a sectional view of a deep groove ball bearing. Fig. 2 is a side view of a crown-shaped resin retainer according to an embodiment of the present invention.
As shown in fig. 1 and 2, the deep groove ball bearing 1 includes an inner ring 2, an outer ring 3, a plurality of balls 4 rotatably interposed between the inner ring 2 and the outer ring 3, and a crown-shaped resin cage 5 housing the balls 4. In the following description, the axial direction indicates a direction along the axis P of the deep groove ball bearing 1. The radial direction indicates a direction perpendicular to the axis P of the deep groove ball bearing 1.
The inner ring 2 is a radially inner raceway ring that guides the balls 4. The inner race 2 has an annular inner race raceway surface 2a on an outer peripheral surface thereof for rolling the balls 4. The inner ring raceway surface 2a is a groove having an arc-shaped cross section when viewed in an axial cross section.
The outer ring 3 is a radially outer raceway ring that guides the balls 4. The outer ring 3 has an inner diameter larger than the outer diameter of the inner ring 2. The outer ring 3 has an annular outer ring raceway surface 3a on an inner peripheral surface thereof for rolling the balls 4. The outer ring raceway surface 3a is a groove having an arc-shaped cross section when viewed in an axial cross section. The outer ring 3 is located on the same axis P as the inner ring 2. The outer ring 3 is located at a position where the outer ring raceway surface 3a overlaps the inner ring raceway surface 2a when viewed in the radial direction.
The plurality of balls 4 as rolling elements are spherical rolling elements. The curvature of the surfaces of the plurality of balls 4 is substantially the same as the curvatures of the inner ring raceway surface 2a and the outer ring raceway surface 3 a. The balls 4 are located between the inner race 2 and the outer race 3 and are arranged in the circumferential direction of the inner race 2 and the outer race 3. The plurality of balls 4 are in contact with the inner race raceway surface 2 a. Further, the plurality of balls 4 are in contact with the outer ring raceway surface 3 a. That is, the plurality of balls 4 are sandwiched between the inner ring raceway surface 2a and the outer ring raceway surface 3 a. The plurality of balls 4 rotate on the inner race track surface 2a and the outer race track surface 3 a. Thereby, the plurality of balls 4 are supported so that the outer ring 3 can rotate relative to the inner ring 2.
The crown-shaped resin cage 5 as a resin cage is a member that holds the plurality of balls 4. The crown-shaped resin holder 5 is made of polyamide 46(PA46), polyamide 66(PA66), polyamide 9T (PA9T), or the like, which is a polyamide synthetic resin. Further, as the reinforcing material, Glass Fiber (GF), Carbon Fiber (CF), or the like may be contained in the synthetic resin. The crown-shaped resin holder 5 is formed in a cylindrical shape. The crown-shaped resin holder 5 has a plurality of pockets 5a that individually hold the balls 4. The plurality of pocket portions 5a are arranged at equal intervals in the circumferential direction of the crown-shaped resin holder 5. The pocket portion 5a is a spherical concave portion recessed from one end portion to the other end portion in the axial direction. The curvature of the pocket portion 5a is smaller than that of the ball 4. That is, the pocket portion 5a is formed of a spherical surface having a larger radius than the ball 4. Thus, the crown-shaped resin holder 5 generates a gap between the surface of the ball 4 and the surface of the pocket portion 5a when the ball 4 is positioned in the pocket portion 5 a.
As shown in fig. 2, the crown-shaped resin holder 5 has a pair of claw portions 5b extending to one side in the axial direction at each of the plurality of pocket portions 5 a. The side surfaces of the pair of claw portions 5b on the side of the pocket portion 5a have a spherical surface continuous with the spherical surface of the pocket portion 5 a. Further, the spherical surface portion of the pocket portion 5a and the spherical surface portion of the claw portion 5b have the same curvature. Thus, the claw portion 5b constitutes a part of the spherical portion of the pocket portion 5 a. The minimum interval between the leading ends of the pair of claw portions 5b is smaller than the maximum width in the circumferential direction of the crown-shaped resin holder 5 of the pocket portion 5 a. That is, the pair of claw portions 5b restrict the amount of movement in the axial direction of the ball 4 located inside the pocket portion 5 a. Thereby, the crown-shaped resin holder 5 can hold the balls 4 in the pocket 5a by the pair of claw portions 5b and allow the balls 4 to rotate in the pocket 5 a. Further, the crown-shaped resin cage 5 holds the balls 4 so that the balls 4 can move in the pocket portions 5a within the range of the gap between the balls 4 and the pocket portions 5 a.
As shown in fig. 1 and 2, the deep groove ball bearing 1 configured as described above is configured such that the outer ring 3 and the inner ring 2 are relatively rotatable via a plurality of balls 4. The plurality of balls 4 are held at a predetermined interval between the inner ring 2 and the outer ring 3 by a crown-shaped resin cage 5. When the outer ring 3 and the inner ring 2 rotate relative to each other, the deep groove ball bearing 1 rotates on the inner ring raceway surface 2a and the outer ring raceway surface 3a in a state where the plurality of balls 4 are held by the pockets 5a of the crown-shaped resin cage 5. The plurality of balls 4 rotate within the pockets 5a and revolve in the circumferential direction of the deep groove ball bearing 1 together with the crown-shaped resin holder 5. The crown-shaped resin holder 5 moves in the radial direction by an amount corresponding to the clearance of the balls 4 with the pockets 5a and revolves together with the plurality of balls 4.
Next, advance and retard of the balls 4 with respect to the pocket portions 5a of the crown-shaped resin cage 5 will be described using fig. 3 and 4. Fig. 3 is a schematic diagram of a load state due to advance and retard of the rolling elements with respect to the crown-shaped resin cage relating to the embodiment of the present invention. Fig. 4 is a graph showing a relationship between a load and a rolling element diameter under predetermined conditions in the crown-shaped resin cage according to the embodiment of the present invention.
As shown in fig. 3, when a radial load and an axial load are applied to the deep groove ball bearing 1, the revolution speed of the balls 4 varies depending on the angle of the contact angle, which is the angle between the direction of the load applied to the inner ring raceway surface 2a or the outer ring raceway surface 3a and the balls 4, and the direction perpendicular to the axis P of the deep groove ball bearing 1. On the other hand, the revolution speed of the crown-shaped resin holder 5 is a constant value. Therefore, the deep groove ball bearing 1 is in a state where the balls 4 move (advance) in the revolving direction faster than the crown-shaped resin cage 5 and in a state where the balls 4 move (retard) in the revolving direction slower than the crown-shaped resin cage 5 due to the change in the contact angle. When the revolution speed of the balls 4 is slower than the revolution speed of the crown-shaped resin holder 5, the crown-shaped resin holder 5 presses the balls 4 in the revolution direction. When the revolution speed of the balls 4 is higher than the revolution speed of the crown resin holder 5, the balls 4 press the crown resin holder 5 in the revolution direction. Thereby, the crown-shaped resin holder 5 generates a compressive load and a tensile load in a rotating manner (see black arrows). Further, the cross section of the bottom portion of the pocket portion 5a where the cross section area of the crown-shaped resin holder 5 in the axial direction is the smallest generates the maximum compressive stress and the maximum tensile stress.
As shown in fig. 4, when the deep groove ball bearing 1 is used in a transmission under the following use conditions, for example, the load applied to the crown-shaped resin cage 5 can be calculated from the equation (2) based on the measurement result. As shown in the formula (2), the maximum load F applied to the crown-shaped resin cage 5 can be approximated by a linear function having the diameter Da of the ball 4 as a variable. As shown in the formula (2), the predetermined maximum load F applied to the crown-shaped resin cage 5 can be calculated from the use of the deep groove ball bearing 1 and the diameter Da of the ball under the use condition.
[ formula 2]
F＝23.7Da-78.4…(2)
F: maximum load applied to the crown-shaped resin holder 5, Da: the diameter of the ball 4.
Error (mismatch) amount: 2/1000mm/mm, radial load: 0.165Cr, axial load: 0.07Ca, rotation speed: maximum allowable rotation speed at oil lubrication, lubricating oil: a transmission oil.
Next, a reduction rate α of the fatigue limit U in the crown-shaped resin cage 5 at the welded portion W of the crown-shaped resin cage 5 will be described with reference to fig. 5. Fig. 5 is a schematic diagram of a fatigue test of a crown-shaped resin holder of the embodiment of the present invention. The weld portion W is a stripe-shaped joint portion generated by joining together molten resins having increased viscosity due to cooling of the tip portion in the mold.
As shown in fig. 5, in the fatigue test of the crown-shaped resin holder 5, a pair of semicircular jigs J apply predetermined forces (see black arrows) to the inner circumferential surface of the crown-shaped resin holder 5 in the radially outward direction at predetermined periods. A tensile load in the radial outer direction is repeatedly applied to the crown-shaped resin holder 5. At this time, the crown-shaped resin holder 5 was subjected to a fatigue test in a state where the welded portion W was located in the gap between one jig J and the other jig J. Thereby, the maximum tensile load is applied to the welded portion W in the crown-shaped resin holder 5. Thus, the crown-shaped resin holder 5 estimates the fatigue limit Uw of the weld W by a fatigue test. Further, the fatigue limit U of the resin material of the crown-shaped resin holder 5 was also estimated using a non-reinforced dumbbell-shaped test piece having no weld portion W.
The reduction rate α due to the welded portion W in the fatigue limit U of the crown-shaped resin holder 5 is calculated from the ratio of the fatigue limit Uw of the welded portion W of the crown-shaped resin holder 5 to the fatigue limit U of the non-reinforced dumbbell-shaped test piece. For example, when the fatigue limit U of the non-reinforced dumbbell test piece and the fatigue limit Uw of the welded portion W of the crown-shaped resin holder 5 are used, the reduction rate α of the fatigue limit U of the welded portion W can be expressed as Uw/U. For example, when the reduction rate of the fatigue limit U by the welded portion W is 0.63, the fatigue limit Uw of the welded portion W of the crown-shaped resin holder 5 is reduced to 63% of the fatigue limit U of the resin material of the crown-shaped resin holder 5 by the welded portion W. The reduction rate α of the fatigue limit U by the weld portion W varies depending on the material used for the crown-shaped resin holder 5, and varies from 0.6 to 0.8 as an example.
Next, the relationship between the fatigue limit U of the resin material of the crown-shaped resin holder 5 and the shape will be described with reference to fig. 6. Fig. 6 is a graph showing a relationship between a radial thickness of the crown-shaped resin cage and a diameter of the rolling element according to the embodiment of the present invention.
As shown in fig. 6, the crown-shaped resin retainer 5 does not cause fatigue failure even if the welded portion W is present, as long as the maximum stress value generated in the crown-shaped resin retainer 5 is 6 to less than 8 of the fatigue limit U of the resin material of the crown-shaped resin retainer 5. Therefore, in the crown-shaped resin holder 5, the bottom portion of the pocket portion 5a having the weld portion W and the smallest cross-sectional area in the axial direction satisfies the formula (3), and thus the fatigue fracture does not occur even if a predetermined maximum load F is applied.
[ formula 3]
F: maximum load applied to the crown-shaped resin holder 5, U: fatigue limit of resin forming the crown-shaped resin holder 5, α: reduction rate of fatigue limit U by fusion-bonded portion W of crown-shaped resin cage 5, S: the sectional area of the portion of the crown-shaped resin holder 5 having the smallest sectional area in the axial direction.
The cross-sectional area S of the bottom portion of the pocket portion 5a having the smallest cross-sectional area in the axial direction of the crown-shaped resin holder 5 (hereinafter referred to as "pocket bottom cross-sectional area S") can be calculated by equation (4).
[ formula 4]
S＝h·t…(4)
S: sectional area of the portion of the crown-shaped resin holder 5 having the smallest sectional area in the axial direction, h: radial thickness of the crown-shaped resin holder 5, t: the thickness of the bottom portion of the pocket portion 5a in the axial direction.
The crown-shaped resin holder 5 is located between the inner ring 2 and the outer ring 3 in such a manner that the axis P of the inner ring 2 and the outer ring 3 coincides with the axis P of the crown-shaped resin holder 5. Further, the crown-shaped resin cage 5 holds the plurality of balls 4 in a state of being relatively rotatable with respect to the inner ring 2 and the outer ring 3. That is, in the deep groove ball bearing 1, the inner ring 2 and the outer ring 3 are always spaced apart from the crown-shaped resin cage 5 (see fig. 1). Thus, the radial thickness h of the crown-shaped resin cage 5 is included in a range where the balls 4 do not come into contact with the inner ring 2 and the outer ring 3 even if the clearance between the balls and the pockets 5a is moved in the radial direction by an amount corresponding to the clearance.
Further, the deep groove ball bearing 1 determines the radial interval between the inner ring 2 and the outer ring 3 according to the diameter Da of the balls 4. Also, the crown-shaped resin cage 5 determines the thickness h in the radial direction in accordance with the diameter Da of the retained ball 4. The radial thickness h is proportional to the diameter Da of the ball 4. The radial thickness h is calculated according to equation (3).
[ formula 5]
h＝0.595Da-0.4181…(5)
h: radial thickness of the crown-shaped resin holder 5, Da: the diameter of the ball 4.
The pocket bottom sectional area S of the crown-shaped resin cage 5 is calculated from the formula (6) expressed based on the formulas (4) and (5) using the thickness t in the axial direction of the bottom portion of the pocket portion 5a and the diameter Da of the ball 4. In addition, the bottom of the pocket portion 5a of the crown-shaped resin holder 5 is a spherical surface. Thus, the thickness t in the axial direction of the bottom portion of the pocket portion 5a is the thinnest thickness t.
[ formula 6]
S＝(0.595Da-0.4181)·…(6)
From the above description, the thickness t in the axial direction of the crown-shaped resin cage 5 is expressed by the maximum load F applied to the crown-shaped resin cage 5, the diameter Da of the ball 4, and the fatigue limit U of the resin forming the crown-shaped resin cage 5 according to equations (3) and (6). The crown-shaped resin holder 5 does not cause fatigue failure even if the fusion-bonded portion W is provided, by making the thickness t in the axial direction satisfy formula (7).
[ formula 7]
On the other hand, in the deep groove ball bearing 1, the crown-shaped resin cage 5 does not protrude from the axial side surfaces of the inner ring 2 and the outer ring 3. That is, in the crown-shaped resin cage 5, the thickness t in the axial direction of the bottom portion of the pocket portion 5a is smaller than the difference between the radius of the balls 4 and 1/2 of the axial width B of the inner ring 2 and the outer ring 3 with respect to the axial center of the deep groove ball bearing 1. Accordingly, the axial thickness t of the crown-shaped resin cage 5 is located in the range inside the axial width B of the inner ring 2 and the outer ring 3 by satisfying the relationship expressed by the equation (8).
[ formula 8]
The crown-shaped resin cage 5 is set to have the thickness t in the axial direction so as to satisfy the formula (1) derived from the formulas (7) and (8), so that it does not protrude from the axial side surfaces of the inner ring 2 and the outer ring 3, and fatigue failure does not occur even when the maximum load F is applied.
[ formula 1]
In the crown-shaped resin cage 5 of the present embodiment, the thickness t in the axial direction of the pocket bottom cross-sectional area S, which is considered to generate the maximum stress, is set so as to satisfy the formula (1). The crown-shaped resin cage 5 incorporated in the deep groove ball bearing 1 has a thickness h in the radial direction which does not contact the inner ring 2 and the outer ring 3, and has a thickness in the axial direction such that a stress generated in the pocket bottom cross-sectional area S when a supposed maximum load F of the crown-shaped resin cage 5 is applied to the resin cage is lower than a fatigue limit U of the resin constituting the crown-shaped resin cage 5. Further, the bottom portion of the pocket portion 5a of the crown-shaped resin retainer 5 assembled into the deep groove ball bearing 1 is located between the axial side faces of the inner and outer rings 2, 3 and the axial direction of the balls 4. That is, the crown-shaped resin cage 5 is contained in the volume of the deep groove ball bearing 1 surrounded by the inner ring 2 and the outer ring 3. In this way, equation (1) calculates the range of the thickness t in the axial direction necessary for the crown-shaped resin cage 5 to satisfy the function from the axial width B of the deep groove ball bearing 1, the diameter Da of the ball 4, and the allowable load (maximum load F) of the crown-shaped resin cage 5. Thereby, the crown-shaped resin cage 5 can have a strength equal to or higher than the fatigue limit U within the range of the maximum load F applied to the crown-shaped resin cage 5 without protruding from the axial side surfaces of the inner ring 2 and the outer ring 3.
Further, the fatigue limit U of the crown-shaped resin holder 5 can be increased by forming the crown-shaped resin holder 5 of a polyamide synthetic resin having excellent toughness, impact resistance, and flexibility, or by including Glass Fibers (GF), Carbon Fibers (CF), or the like. Thus, the crown-shaped resin cage 5 can expand the range of the axial thickness t required to have a strength equal to or higher than the fatigue limit U within the range of the maximum load F applied to the crown-shaped resin cage 5 without protruding from the axial side surfaces of the inner ring 2 and the outer ring 3.
Further, by considering the reduction rate α of the fatigue limit U by the welded portion W of the crown-shaped resin holder 5, even if the welded portion W exists at the bottom portion of the pocket portion 5a where the maximum stress is generated in the crown-shaped resin holder 5, the stress generated in the case where the assumed maximum load F of the crown-shaped resin holder 5 is applied to the crown-shaped resin holder 5 is made lower than the fatigue limit U of the resin forming the crown-shaped resin holder 5. Thereby, the crown-shaped resin cage 5 can have a strength equal to or higher than the fatigue limit U in the range of the maximum load F applied to the crown-shaped resin cage 5 without protruding from the axial side surfaces of the inner ring 2 and the outer ring 3.
While the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, which are merely examples, and it is needless to say that the present invention can be carried out in various embodiments within a range not departing from the gist of the present invention, and the scope of the present invention includes all modifications within the meaning and scope equivalent to the scope of the claims.
In the present embodiment, the deep groove ball bearing 1 is described, but the present invention can be applied to all bearings having a plurality of rolling elements. Similarly, in the present embodiment, the crown-shaped resin cage 5 is described, but the present invention can be applied to a resin cage that holds rolling elements.
In the present embodiment, the crown-shaped resin holder 5 is made of a polyamide synthetic resin, but is not limited thereto. The crown-shaped resin retainer may be made of synthetic resin.
Description of the reference numerals
1 deep groove ball bearing
2 inner ring
2a inner race raceway surface
3 outer ring
3a outer ring raceway surface
4 ball
5 crown-shaped resin retainer
5a pocket part
F maximum load applied to crown-shaped resin holder
Fatigue limit of U-shaped resin constituting crown-shaped resin holder
Reduction rate of fatigue limit U due to welding part W of alpha crown-shaped resin cage
Diameter of Da ball
thickness of bottom part of t-pocket part in axial direction
Axial width of B deep groove ball bearing
Cross-sectional area of portion of S-crown-shaped resin retainer having smallest cross-sectional area in axial direction
h radial thickness of the crown-shaped resin retainer.
Claims (4)
1. A resin retainer that retains a plurality of rolling elements of a deep groove ball bearing at equal intervals, characterized in that:
the thinnest thickness in the axial direction of the portion where the cross-sectional area in the axial direction of the pocket portion holding the rolling elements is smallest is included in the range calculated by the formula (1),
wherein the resin retainer is positioned in a range in which the resin retainer is positioned inside the axial width of the deep groove ball bearing while a stress generated in a portion where the axial cross-sectional area is smallest when a predetermined maximum load is applied to the resin retainer is lower than a fatigue limit of the resin retainer,
[ formula 1]
F: maximum load applied to the resin holder, U: fatigue limit of resin constituting the resin holder, α: a reduction rate indicating a rate at which the fatigue limit of the resin constituting the resin holder is reduced by the weld portion as the joint portion of the resin, Da: diameter of rolling element, t: the axial thickness of the portion of minimum cross-sectional area, B: the axial width of the deep groove ball bearing.
2. The resin holder as set forth in claim 1, wherein:
the resin forming the resin holder is a polyamide synthetic resin.
3. The resin holder as set forth in claim 1 or 2, wherein:
the resin forming the resin holder contains a fiber-reinforced resin.
4. The resin holder as set forth in any one of claims 1 to 3, wherein:
a reduction rate of the resin constituting the resin holder, which represents a rate of reduction of the fatigue limit by the welded portion, is 0.6 or more and 0.8 or less.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2021-052191 | 2021-03-25 | ||
| JP2021052191A JP2022149864A (en) | 2021-03-25 | 2021-03-25 | Resin cage |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115126779A true CN115126779A (en) | 2022-09-30 |
Family
ID=83376931
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210277688.2A Pending CN115126779A (en) | 2021-03-25 | 2022-03-21 | Resin retainer |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP2022149864A (en) |
| CN (1) | CN115126779A (en) |
-
2021
- 2021-03-25 JP JP2021052191A patent/JP2022149864A/en active Pending
-
2022
- 2022-03-21 CN CN202210277688.2A patent/CN115126779A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JP2022149864A (en) | 2022-10-07 |
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