JPH0216861B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fatigue testing machine for ball bearing retainers, and in particular, to a fatigue testing machine for ball bearing retainers, which can be used to test dynamic retainers under conditions close to those in actual use, and in a short period of time. This invention relates to a fatigue testing machine for ball bearing retainers that can perform strength comparison tests.

[Conventional technology]

In general, the strength of retainers in ball bearings is determined by comparing the strength of different materials such as iron plate, Bakelite, and nylon,
Comparison of strength due to differences in column width, shape, etc., usage conditions,
For example, a study is carried out by comparing the strength due to differences in rotational speed, load, lubrication, temperature, etc., and comparing the strength of each part of the retainer.

By the way, the strength of the retainer in ball bearings is
It is very difficult to analyze it theoretically, and in tests under actual usage conditions, it takes a long time for the retainer to break, so until now comparative studies have been conducted using the following simple tests.

Non-lubrication test: A method of evaluating bearings by operating them without lubrication and causing the bearings to seize up.

Drop test: A method of evaluating bearings by dropping them from a predetermined height.

Swing torque test: A method of evaluation in which force is applied externally to the rolling elements, and force is applied to the retainer in tension, compression, or both directions.

[Problem to be solved by the invention]

Retainer damage in the above-mentioned no-lubrication test and drop test is evaluated under test conditions that are far from actual usage conditions, so for comparison of retainer strength,
It was not an appropriate evaluation. In addition, the swing torque test can be performed under conditions close to those in which the bearing is actually used, but this method requires that some of the rolling elements be fixed; Special equipment or devices had to be used.

Therefore, this invention provides a ball bearing retainer fatigue tester that performs a comparative strength test of the retainer by breaking the retainer in a short time without using any special equipment or ingenuity under conditions that reproduce the environment and conditions during use. developed.

[Means to solve the problem]

The present invention was made to solve the above-mentioned problems, and includes a main shaft that is rotatably driven by a driving means such as a motor, and an inner and outer shaft that is set on the main shaft and provided concentrically. A ring and a plurality of balls held between the inner and outer rings are provided, two rolling surfaces with different centers of curvature are formed on each of the inner and outer rings, and each of the rolling surfaces and the balls contact each other at one point. A ball bearing retainer fatigue tester is constructed of a test retainer built-in unit of a four-point contact type, and a moment load means for applying a moment load to the test retainer built-in unit.

Furthermore, the present invention adds thrust loading means to the above-mentioned structure for applying a thrust load to the test retainer built-in unit.

Further, in the present invention, each raceway surface of the inner and outer rings in the test retainer built-in unit is made asymmetrical.

Furthermore, in the present invention, each raceway surface of the inner and outer rings in the test retainer built-in unit has an infinite radius of curvature, that is, a straight line.

[Effect]

According to the fatigue testing machine for ball bearing retainers of the present invention, the rotation axis of the balls orbiting between the inner and outer rings in the test retainer built-in unit changes at that angular position, and at that time, the contact pressure at each contact point also changes. As a result, a difference occurs in the revolution speed between the balls, and a large interference force is generated between the balls and the test retainer, which can lead to fatigue failure of the test retainer.

Furthermore, by applying a thrust load to the test retainer-incorporated unit using the thrust load means, the load range is expanded and a large difference in revolution speed can be obtained even between adjacent balls.

Furthermore, by making the respective raceway surfaces of the inner and outer rings of the test retainer incorporated unit asymmetrical, the difference in revolution speed between the balls becomes large, and the test retainer can be brought to fatigue failure in a shorter time.

Furthermore, by making the rolling surfaces of the inner and outer rings in the test retainer built-in unit straight, the unit can be simplified and the test retainer can be prevented from fatigue failure due to the difference in revolution speed between the balls, as described above. .

〔Example〕

Embodiments of the invention will be described based on the drawings.

In Figure 1, 1 is a motor (not shown), V
The main shaft 4 is rotatably driven by a driving means consisting of a belt 2, a pulley 3, etc., and 4 is a test retainer built-in unit (hereinafter simply referred to as a 5 is a bearing box fixed to the base 6 that supports the unit 4; 7 is a thrust load bearing provided at the end of the main shaft 1 on the unit 4 side;
8 is a thrust load means that supports the thrust load bearing 7 and applies a thrust load Fa to the unit 4; 9 is a moment load bearing provided on the end of the main shaft 1 opposite to the unit 4 side; 10 is a moment load means; Free bearing box 11 supporting load bearing 9
is a moment load means connected to the bearing box 10 and applying a moment load Mo to the unit 4.

Here, the main shaft 1 is rotatably supported by the bearing boxes 5 and 10 via the unit 4 and the moment load bearing 9, and by moving the free bearing box 10 with the moment loading means 11, the main shaft 1 can be moved. Apply moment load Mo to unit 4 by tilting it.
give.

As shown in FIG. 2, the unit 4 includes an outer ring 41, an inner ring 42, and a plurality of balls 43 held between the inner and outer rings, which are provided concentrically. The outer ring 41 has raceway surfaces 44a and 44b on the inner peripheral surfaces of the outer ring members 41a and 41b, respectively, and the inner ring 42
has raceway surfaces 45a and 45b on the outer peripheral surfaces of inner ring members 42a and 42b, respectively, and raceway surface 4 of outer ring 41
4a, 44b and raceway surfaces 45a, 45 of the inner ring 42
It is a four-point contact type in which b and the ball 43 are in contact at one point each, and at the angular position of the ball 43 (at each position of the ball 43 revolving between the inner and outer rings 41 and 42) with respect to the direction of the moment load Mo. ball 43
The rolling surfaces 44a, 44b and Raceway surface 45 of inner ring 42
a and 45b are respectively asymmetrical. That is,
Even with symmetrical four-point contact as shown in Figure 7, depending on the load conditions, as shown in Figures 8 and 9,
The axis of rotation of the ball changes depending on the angular position, and then,
The contact surface pressure at each contact point of the ball also changes, causing the ball to lag and advance. However, in the case of the symmetrical four-point contact tested as shown in Figure 10,
The contact surface pressure at each contact point at an angular position has the same tendency as a symmetrical four-point contact, but the ball's rotation axis differs between contact points A-D and B-C, and the number of revolutions of the ball at that time N _AD , N _BC is, when the contact point A-D is N _AD = d _D / d _D + d _A・Ni When the contact point B-C is N _BC = d _C / d _C + d _B・Ni, Ni: inner ring rotation speed d _A : Contact diameter of contact point A d _B : Contact diameter of contact point B d _C : Contact diameter of contact point C d _D : Contact diameter of contact point D (see Figure 10) d _D - d _C and d _B - The difference in d _A also causes a difference in the number of revolutions N _AD and N _BC of the ball. Therefore, this d _D −d _C
The difference between _dB and _dA causes a larger revolution speed, which causes a large stress to be applied to the retainer.

In the above configuration, when the motor is driven,
The rotation of the motor is transmitted to the main shaft 1 via the V-belt 2 and pulley 3, and the inner ring 42 of the unit 4 set on the main shaft 1 rotates.

In this state, the moment load means 11 slightly tilts the main shaft 1 to apply a moment load Mo to the unit 4. If necessary, a thrust load Fa is applied to the unit 4 by the thrust load means 8 in order to further increase the difference in the revolution speed. Then, the axis of rotation at the angular position of the ball 43 revolving between the inner and outer rings 41 and 42 of the unit 4 will be different in the direction of the moment load Mo, for example in the vertical direction, and at that time, the contact points of the balls will be different. The surface pressure also changes, causing the balls to lag and advance, resulting in a difference in the revolution speed between the balls 43. Furthermore, the unit 4 of the embodiment has contact points A, B, C, D.
is asymmetric, a large difference in revolution speed is obtained, and a large stress is applied to the test retainer 4' from the balls 43, causing fatigue failure of the test retainer 4'. It is possible to apply a load in a state extremely similar to that in actual use, and it is possible to perform a fatigue failure test, that is, a comparative strength test, on the test retainer 4'.

According to the apparatus of the present invention, a dynamic strength comparison test of a ball bearing retainer can be conducted in a short period of time under conditions extremely close to the conditions in which the bearing is actually used.

3 to 5 show other embodiments of the unit 4. In FIGS. 3 and 4, one of the outer ring 41 and the inner ring 42 has the contact points B and C largely shifted, and the fifth In the figure, the raceway surfaces 44a, 44b and 45a, 45b of the outer ring 41 and the inner ring 42 have infinite radii of curvature, that is, are formed into straight lines. In addition, FIG. 6 shows the raceway surfaces 44 of the outer ring 41 and the inner ring 42.
This is a unit in which a, 44b and 45a, 45b are formed symmetrically.

It should be noted that the moment load alone can damage the retainer, but in this case, the rotation axis of the ball only changes mainly at 180° opposing positions (for example, up and down), and the load applied to the test retainer 4' is the condition. becomes more relaxed. Therefore, in order to obtain stricter test conditions, if a thrust load is applied as in the above embodiment, the load range in the upper half is expanded, and a large difference in revolution speed is obtained between adjacent balls. Further, as for the retainer type, any type that can be used for ball bearings such as crown type and corrugated type can be used.

〔Effect of the invention〕

As explained above, according to the ball bearing retainer fatigue testing machine of the present invention, dynamic retainer strength comparison tests can be performed in a short period of time under conditions extremely similar to the conditions in which the bearing is actually used. make it possible,
In addition, since there is no need for special equipment or ingenuity, it can be of great help in comparing retainers, strength tests, countermeasures, and research and development.

Additionally, the addition of thrust loading means expands the load range and allows testing under more severe test conditions.

Furthermore, since the raceway surfaces of the inner and outer rings are asymmetrical,
The difference in the degree of revolution between the balls is increased, making it possible to perform dynamic retainer strength comparison tests in a shorter time.

Furthermore, since the raceway surfaces of the inner and outer rings are straight lines, it is possible to simplify the test retainer-incorporated unit and perform retainer strength comparison tests.

[Brief explanation of drawings]

Fig. 1 is an overall configuration drawing showing an embodiment of a ball bearing retainer fatigue testing machine according to the present invention, Fig. 2 is a vertical cross-sectional view of essential parts showing a test retainer built-in unit used in the above testing machine, and Fig. 3 6 to 6 are longitudinal sectional views of main parts showing other embodiments of the test retainer built-in unit, and FIGS. 7 to 10 are drawings for explaining the difference in ball delay and advance in symmetrical and asymmetrical cases. DESCRIPTION OF SYMBOLS 1... Main shaft, 4... Test retainer built-in unit, 7... Thrust load bearing, 9... Moment load bearing, 10... Thrust load means, 11
... Moment load means, 41 ... Outer ring, 41
a, 41b... Outer ring member, 42... Inner ring, 42
a, 42b... Inner ring member, 43... Ball, 44
a, 44b, 45a, 45b...Rolling surface, A,
B, C, D...Contact points.

Claims (1)

[Scope of Claims] 1. A main shaft rotationally driven by a driving means such as a motor, an inner and outer ring set on the main shaft and provided concentrically, and a plurality of balls held between the inner and outer rings. A test retainer built-in unit comprising: a four-point contact type in which two raceway surfaces with different centers of curvature are formed on the inner and outer rings, and each of the raceway surfaces and the ball contact each other at one point; A fatigue testing machine for a ball bearing retainer, comprising a moment loading means for applying a moment load to the test retainer built-in unit. 2. The ball bearing retainer fatigue testing machine according to claim 1, further comprising a thrust loading means for applying a thrust load to the test retainer built-in unit. 3. The ball bearing retainer fatigue testing machine according to claim 1, wherein each raceway surface of the inner and outer rings in the test retainer built-in unit is asymmetrical. 4. The ball bearing retainer fatigue testing machine according to claim 3, wherein each raceway surface of the inner and outer rings in the test retainer built-in unit has an infinite radius of curvature, that is, a straight line.