JP4704102B2 - Bearing test apparatus and bearing test method - Google Patents

Description

  The present invention relates to a bearing test apparatus and a bearing test method for testing the durability life of a rolling bearing.

  A bearing test apparatus for testing the endurance life of a rolling bearing includes a rotating shaft to which an inner ring of the test bearing is attached, a housing for fixing an outer ring of the test bearing, and a rotational driving means for rotationally driving the rotating shaft, and a test bearing. Many are provided with a load loading means for loading a load (see, for example, Patent Document 1). These bearing test apparatuses are used for bearing design, development, quality assurance, trouble investigation, and the like.

  On the other hand, in rolling bearings that support alternators, etc., which are auxiliary equipment for automobiles, even if the bearing test equipment as described above guarantees a sufficient endurance life, brittle delamination is quickly caused on the raceway surface on the fixed ring side. Is known to occur. It is known that the occurrence of this brittle peeling depends on the type of grease enclosed in the bearing.

  Various investigations have been made on the cause of this brittle peeling, but as a result of hydrogen analysis of the bearing after the bearing test in a cycle of repeated acceleration and deceleration, the amount of hydrogen increased in the fixed ring, and this was the case for the rotating wheel and rolling element. Since no significant increase in the amount of hydrogen was observed, it is presumed to be due to hydrogen embrittlement of the steel forming the stationary ring (see, for example, Non-Patent Document 1). That is, the grease encapsulated in the bearing is decomposed using the new surface generated on the raceway surface by sliding with the rolling element as a catalyst, and hydrogen generated by this decomposition penetrates into the steel of the raceway surface, causing hydrogen embrittlement. It is considered a thing.

Japanese Patent Laid-Open No. 3-128430 (FIG. 2) Tamada, Tanaka “Reproduction experiment of brittle debonding due to rotation of outer ring” Tribology Conference Proceedings of Japan Tribology Society, October 1994, p. 749-752

  The conventional bearing test apparatus described in Patent Document 1 cannot reproduce brittle delamination as described above, and has a problem that it is impossible to evaluate a decrease in bearing life due to brittle delamination considered to be caused by hydrogen embrittlement. For this reason, bearings used for alternators, tension pulleys, idler pulleys, timing belt pulleys, electromagnetic clutches, compressors, water pumps and other automotive auxiliary machines, bearings supporting shafts incorporated in engines such as crankshafts and camshafts. It can be effectively used for the design, development, quality assurance, etc. of rolling bearings used in applications where there is a risk of brittle delamination, such as bearings that support the rotating shafts of various motors and machine tools. A bearing test device is desired.

  Accordingly, an object of the present invention is to provide a bearing test apparatus and a bearing test method capable of accurately reproducing and evaluating a decrease in bearing life due to brittle peeling.

  In order to solve the above-described problems, a bearing test apparatus according to the present invention includes a rotating shaft to which an inner ring of a test bearing in which inner and outer rings and rolling elements are formed of a conductor are attached, and a housing that fixes the outer ring of the test bearing. A bearing test apparatus provided with a rotation driving means for rotating the rotation shaft and a load loading means for applying a load to the test bearing, wherein the rolling element is disposed between an inner ring and an outer ring of the test bearing. The structure which provided the electricity supply means to send an electric current through was employ | adopted.

  In other words, by providing a current-carrying means for passing current through the rolling elements between the inner and outer rings of the test bearing, hydrogen is forcibly generated by electrolysis from the grease sealed in the bearing, resulting in hydrogen embrittlement. Therefore, the brittle peeling considered to be reproducible can be accurately evaluated for the reduction in bearing life due to the brittle peeling.

  The energizing means is provided with a dummy bearing in which the rotating shaft is supported at a position away from the test bearing, and inner and outer rings and rolling elements are formed of a conductor. The outer ring of the dummy bearing is the outer ring of the test bearing. The test bearing and the dummy bearing housing and the rotating shaft are formed of a conductor, and the test bearing and the dummy bearing housing are energized. Thus, an electric current can be easily passed between the outer ring and the inner ring of the test bearing via the rolling element without using a contact for a rotating body such as a slip ring.

  The rotation drive means is provided with an output shaft of a motor parallel to the rotation shaft, and an extension portion extended from a mounting portion of a test bearing is provided on the rotation shaft. The extension portion of the rotation shaft and the motor A pulley is attached to the output shaft, an endless belt is stretched between these pulleys, and the rotary shaft is driven by a belt. The load loading means loads the extension portion of the rotary shaft with the tension of the endless belt. Therefore, a separate load loading means is not required, and the bearing test apparatus can have a simple configuration.

  By making the rotation driving means capable of providing a rotation cycle in which acceleration and deceleration are repeated, the bearing test conditions can be made close to the state of use in an actual machine.

  The ratio P / C between the dynamic equivalent load P applied to the test bearing by the load loading means and the basic dynamic load rating C of the test bearing is preferably 0.05 or more in order to cause brittle peeling. . In addition, P / C under the normal use conditions of the rolling bearing in the use which may generate | occur | produce the brittle peeling mentioned above is 0.2 or less.

  In the bearing test method of the present invention, an inner ring of a test bearing in which inner and outer rings and rolling elements are formed of a conductor are attached to a rotating shaft, the outer ring of the test bearing is fixed to a housing, and a load is applied to the test bearing. In the bearing test method for rotationally driving the rotary shaft while applying a load, a method of rotationally driving the rotary shaft while passing an electric current between the inner ring and the outer ring of the test bearing via the rolling elements is adopted. Therefore, hydrogen can be forcibly generated from the grease sealed in the bearing by electrolysis, making it possible to reproduce the brittle delamination that may be caused by hydrogen embrittlement, and to accurately evaluate the decrease in bearing life due to this brittle exfoliation. did.

  The bearing test apparatus of the present invention forcibly generates hydrogen by electrolysis from grease sealed in the bearing by providing a current-carrying means for passing a current between the inner ring and the outer ring of the test bearing via a rolling element. As a result, it is possible to reproduce the brittle peeling considered to be caused by hydrogen embrittlement, and it is possible to accurately evaluate the decrease in bearing life due to this brittle peeling, and it is used for applications where brittle peeling may occur. It can be used effectively for the design, development and quality assurance of rolling bearings.

  A housing in which the current-carrying means is supported at a position where the rotating shaft is separated from the test bearing, a dummy bearing in which inner and outer rings and rolling elements are formed of a conductor is provided, and the outer ring of the dummy bearing is fixed to the outer ring of the test bearing The slip ring is formed by fixing each of the test bearing and dummy bearing housing and the rotating shaft with a conductor and energizing between the test bearing and the dummy bearing housing. A current can be easily passed through the rolling element between the outer ring and the inner ring of the test bearing without using a contact for a rotating body such as the above.

  The rotation drive means is provided with a drive shaft that is rotated by a motor in parallel with the rotation shaft, and an extension portion that is extended from the mounting portion of the test bearing is provided on the rotation shaft. A pulley is attached to the belt, an endless belt is stretched between these pulleys, the rotating shaft is driven by the belt, and the load is applied to the extension of the rotating shaft by the tension of the endless belt. This eliminates the need for a separate load loading means, and allows the bearing test apparatus to have a simple configuration.

  By making the rotation driving means capable of providing a rotation cycle in which acceleration and deceleration are repeated, the bearing test conditions can be made close to the state of use in an actual machine.

  In addition, the bearing test method of the present invention employs a method of rotating the rotating shaft while passing an electric current between the inner ring and the outer ring of the test bearing via a rolling element, so that the grease sealed in the bearing is used. Since hydrogen is forcibly generated by electrolysis, it is possible to reproduce the brittle delamination that may be caused by hydrogen embrittlement, and it is possible to accurately evaluate the decrease in bearing life due to this brittle delamination, and brittle delamination may occur. It can be used effectively for the design, development, quality assurance, etc. of rolling bearings used in certain applications.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, this bearing test apparatus is supported by separate housings 4 a and 4 b in which a rotating shaft 1 is insulated from each other by a test bearing 2 and a dummy bearing 3, and is extended from a mounting portion of the test bearing 2. Pulleys 6a and 6b are respectively attached to an extension 1a of the rotating shaft 1 and an output shaft 5a of the motor 5 disposed in parallel with the rotating shaft 1, and an endless belt 7 is provided between these pulleys 6a and 6b. The rotary shaft 1 is belt-driven, and a radial load is applied to the test bearing 2 by the tension of the endless belt 7 through the extension 1a of the rotary shaft 1. An intermediate shaft with a pulley attached may be provided between the rotary shaft 1 and the output shaft 5a, and the rotary shaft 1 may be belt-driven via this intermediate shaft. In this case, by adjusting the position of the intermediate shaft, the tension of the endless belt 7 stretched between the intermediate shaft and the extended portion 1a of the rotary shaft 1 can be changed.

  Each of the inner rings 2a, 3a, outer rings 2b, 3b of the test bearing 2 and the dummy bearing 3 and the balls 2c, 3c as rolling elements are formed of a conductor, and the inner rings 2a, 3a rotate at intervals from each other. Attached to the shaft 1, the outer rings 2b and 3b are fixed to the housings 4a and 4b, respectively. Although illustration is omitted, grease is sealed in the test bearing 2 and the dummy bearing 3.

  The rotary shaft 1 and the respective housings 4a and 4b are also formed of a conductor, and contact terminals 8a and 8b connected to the positive and negative power supplies (not shown) are attached to the respective housings 4a and 4b. By connecting these contact terminals 8a and 8b to the power source, the outer ring 2b of the test bearing 2, the ball 2c, the inner ring 2a, the rotating shaft 1, the inner ring 3a of the dummy bearing 3, the ball 3c, and the outer ring 3b are sequentially passed from the housing 4a. Thus, a current flows to the housing 4b. Therefore, hydrogen can be forcibly generated from the grease sealed in the test bearing 2 by electrolysis, and the brittle peeling considered to be caused by the hydrogen embrittlement described above can be reproduced.

As an example, a bearing life test was performed using the above-described bearing test apparatus, in which a current was applied between the contact terminals 8a and 8b, and the rotating shaft 1 was driven in a rotational cycle in which acceleration and deceleration were repeated as shown in FIG. As a comparative example, a test for driving the rotary shaft 1 in the same rotation cycle without conducting current between the contact terminals 8a and 8b was also performed. The number of test bearing samples was two for each of the example and the comparative example, and the bearing life was determined by the change in the driving torque of the rotating shaft 1. The test conditions are as follows.
Test bearing: deep groove ball bearing with nominal number 6203 (outer diameter 40 mm, inner diameter 17 mm, width 12 mm)
・ Grease: Urea grease (Base oil: Synthetic hydrocarbon oil)
・ Load: 240kgf (P / C = 0.24)
・ Energization condition: Terminal voltage 4V, Current 3A (Example only)
・ Test time: Censored after 300 hours

  As a result of the bearing life test, the bearing life of all the test bearings exceeded 300 hours of the test time in the comparative example, whereas the bearing life of all the test bearings in the example was about 13 hours. Moreover, as a result of disassembling and visually observing the test bearings of these examples after the test, it was confirmed that brittle peeling occurred on the raceway surface. From the above test results, it was found that the bearing test apparatus and the bearing test method according to the present invention can reproduce the brittle peeling considered to be caused by hydrogen embrittlement, and can accurately evaluate the decrease in the bearing life due to the brittle peeling.

  In the embodiment described above, the test bearing is a deep groove ball bearing and a radial load is applied to the test bearing. However, the bearing test apparatus and the bearing test method according to the present invention use other rolling bearings such as roller bearings as test bearings. These test bearings can also be loaded with thrust loads.

Longitudinal sectional view showing an embodiment of a bearing test apparatus A graph showing a rotation cycle of a rotating shaft in a bearing life test using the bearing test apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotating shaft 1a Extension part 2 Test bearing 3 Dummy bearing 2a, 3a Inner ring 2b, 3b Outer ring 2c, 3c Ball 4a, 4b Housing 5 Motor 5a Output shaft 6a, 6b Pulley 7 Endless belt 8a, 8b Contact terminal

Claims (5)

  A rotating shaft for mounting an inner ring of a test bearing in which inner and outer rings and rolling elements are made of a conductor; a housing for fixing the outer ring of the test bearing; and a rotation driving means for rotating the rotating shaft, and the test In a bearing test apparatus provided with a load loading means for applying a load to the bearing, an energizing means for passing an electric current through the rolling elements is provided between an inner ring and an outer ring of the test bearing, and the energizing means is the rotation The shaft is supported at a position away from the test bearing, and a dummy bearing having inner and outer rings and rolling elements formed of a conductor is provided, and the outer ring of the dummy bearing is insulated from the housing to which the outer ring of the test bearing is fixed. The test bearings and the dummy bearing housings and the rotating shaft are formed of a conductor, and current is passed between the test bearing and the dummy bearing housing. Bearing test device according to symptoms. The rotation drive means arranges an output shaft of the motor in parallel with the rotation shaft, and provides an extension portion extended from the mounting portion of the test bearing on the rotation shaft, and the extension portion of the rotation shaft and the motor A pulley is attached to the output shaft, an endless belt is stretched between these pulleys, and the rotary shaft is driven by the belt, and the load-loading means is attached to the extension portion of the rotary shaft by the tension of the endless belt. The bearing test apparatus according to claim 1, which applies a load. The rotation driving means, the bearing test apparatus according to claim 1 or 2 in which can impart rotational cycle repeats acceleration and deceleration. A dynamic equivalent load P to be loaded to the test bearing by the load application means, according to any one of claims 1 to 3 ratio P / C of the basic dynamic load rating C was 0.05 or more test bearing Bearing test equipment. An inner ring of a test bearing in which inner and outer rings and rolling elements are formed of a conductor are attached to a rotating shaft, the outer ring of the test bearing is fixed to a housing, and the rotating shaft is driven to rotate while applying a load to the test bearing. In the bearing test method, the rotary shaft is supported at a position away from the test bearing, a dummy bearing in which inner and outer rings and rolling elements are formed of a conductor is provided, the rotary shaft is formed of a conductor, and the test is performed. By energizing between the outer ring of the bearing and the outer ring of the dummy bearing , the rotating shaft is driven to rotate while an electric current flows between the inner ring and the outer ring of the test bearing via the rolling elements. Bearing test method characterized by the above.

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