JP2008286662A - Device and method for testing bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for testing a bearing, capable of reproducing brittle separation caused by hydrogen brittleness, in a short time and with precision. <P>SOLUTION: A test bearing 2 and a dummy bearing 3 are mounted at an interval on a rotary axis 1 driven with a belt, to which a load is applied; each outer ring 2b, 3b of the test bearing 2 and a dummy bearing 3 are fixed on mutually insulated housing 4a, 4b, and the cavity part 9 between the housing 4a, 4b is filled with water; the interval between contact terminals 8a, 8b mounted on each housing 4a, 4b is energized; while making a current to flow between the inner ring 2a of the test bearing 2 and the outer ring 2b through a ball 2c, hydrogen is generated forcibly by electrolysis and the like from grease enclosed in the test bearing 2; and generation of hydrogen is accelerated from water itself supplied into the inner part of the bearing 2 and due to increase in electrolytic corrosion by water, thereby brittle separation caused by hydrogen brittleness can be reproduced, in a short time and with precision. <P>COPYRIGHT: (C)2009,JPO&INPIT

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.

  For this reason, the conventional bearing test apparatus as described in Patent Document 1 cannot reproduce the brittle separation as described above, and cannot evaluate the decrease in bearing life due to the brittle separation considered to be caused by hydrogen embrittlement. Bearings used in alternators, tension pulleys, idler pulleys, timing belt pulleys, electromagnetic clutches, compressors, water pumps and other automotive auxiliary equipment, and bearings that support shafts 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 was desired.

  In response to such a demand, the present inventors have forced electrolysis from the grease sealed in the bearing by providing a current-carrying means for passing a current through the rolling element between the inner ring and the outer ring of the test bearing. In the past, a bearing test apparatus and a bearing test method that can generate hydrogen and reproduce brittle delamination considered to be caused by hydrogen embrittlement have been proposed (see Patent Document 2).

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 JP 2006-317273 A

  The bearing test apparatus described in Patent Document 2 can reproduce brittle peeling due to hydrogen embrittlement, but in order to reproduce brittle peeling in a short time, it is necessary to increase the current passed through the bearing test. The bearing life may be evaluated first due to other problems such as electrolytic corrosion, which is insufficient as a brittle peeling reproduction test apparatus. In order to prevent the occurrence of problems such as electrolytic corrosion due to a large current, the current passed through the bearing test may be reduced, but there is a problem that it takes time to reproduce brittle peeling.

  Accordingly, an object of the present invention is to provide a bearing test apparatus and a bearing test method capable of accurately reproducing brittle peeling due to hydrogen embrittlement in a short time.

  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 supplies the water | moisture content to the inside of the said test bearing was provided.

  That is, by providing a current-carrying means for passing a current through the rolling elements between the inner ring and the outer ring of the test bearing, electrolysis from the grease sealed in the bearing and catalysis of the new surface caused by electrolytic corrosion wear This is due to hydrogen embrittlement by forcibly generating hydrogen and supplying water to the inside of the test bearing to promote hydrogen generation from this moisture itself or by increasing electrolytic corrosion due to moisture. Brittle exfoliation can be accurately reproduced in a short time. The moisture supplied to the inside of the test bearing may be previously placed inside the bearing, or the test bearing may be exposed to water or a steam atmosphere to enter the inside of the bearing during the test.

  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 the belt, and the load loading means is loaded on the extension of the rotary shaft by 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 in which the rotating shaft is rotationally driven while being loaded, while supplying current through the rolling elements between the inner ring and the outer ring of the test bearing, moisture is supplied into the test bearing, By adopting a method of rotationally driving the rotating shaft, hydrogen is forcibly generated from the grease sealed in the bearing by electrolysis or catalysis of the new surface caused by electrolytic corrosion, and is supplied to the inside of the bearing. The generation of hydrogen from the water itself or by increasing the electric corrosion wear due to the water is promoted so that the brittle peeling due to hydrogen embrittlement can be accurately reproduced in a short time.

  The bearing test apparatus according to the present invention provides a current-carrying means for passing a current through a rolling element between an inner ring and an outer ring of a test bearing, and supplies moisture to the inside of the test bearing so that grease is sealed in the bearing. Hydrogen is forcibly generated by electrolysis and catalysis of the new surface caused by galvanic wear, and hydrogen is generated from the moisture supplied to the inside of the test bearing and by increasing galvanic wear due to moisture. Designing, developing, and quality assurance of rolling bearings used in applications where such brittle delamination can occur can be accurately reproduced in a short period of time due to hydrogen embrittlement. It can be used effectively.

  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 in which water is supplied to the inside of the test bearing while the current is passed between the inner ring and the outer ring of the test bearing via a rolling element to rotate the rotating shaft. As a result, grease is forcibly generated from the grease sealed in the bearing by electrolysis or catalysis of the new surface caused by electrolytic corrosion wear, and from the moisture supplied inside the bearing itself or by electrolytic corrosion due to moisture. Since the generation of hydrogen due to increased wear is promoted, brittle peeling due to hydrogen embrittlement can be accurately reproduced in a short time, and it is used for applications where such brittle peeling may occur. It can be used effectively for the design, development and quality assurance of rolling bearings.

  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. Further, the cavity 9 formed between the housings 4a and 4b is filled with water so that moisture is supplied to the inside of the test bearing 2. Therefore, hydrogen is forcibly generated from the grease sealed in the test bearing 2 by electrolysis, and hydrogen is generated from moisture itself supplied to the inside of the test bearing 2 or by increasing electrical wear due to moisture. And brittle peeling due to hydrogen embrittlement can be accurately reproduced in a short time.

As an example, using the above-described bearing test apparatus, the cavity 9 between the housings 4a and 4b is filled with water, and electricity is supplied between the contact terminals 8a and 8b, so that the rotary shaft 1 is as shown in FIG. A bearing life test was performed in which the motor was driven with a rotation cycle that repeatedly accelerated and decelerated. Further, as a comparative example, a bearing life test was conducted in the case where water was not poured into the cavity 9 between the housings 4a and 4b. The number of test bearing samples was two for each of the example and the comparative example, and the bearing life was evaluated by the average life of the two test bearings 2 determined by the change in the driving torque of the rotating shaft 1. The test conditions are as follows.
Test bearing: Nominal number 6203 deep groove ball bearing (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 conditions: Terminal voltage 2V, Current 0.5A
・ Test time: Censored in 300 hours

  As a result of the bearing life test, the bearing life was 37 hours in the comparative example, whereas in the example in which the cavity 9 was filled with water and moisture was supplied to the inside of the test bearing, the bearing life was that of the comparative example. It was 15 hours, less than half of that. Moreover, as a result of disassembling and visually observing the test bearings of the example and the comparative example after the test, it was confirmed that brittle peeling occurred on the raceway surface of the outer ring which is a fixed ring. From the above test results, it was confirmed that the bearing test apparatus and the bearing test method according to the present invention can accurately reproduce the brittle peeling due to hydrogen embrittlement in a short time.

  In the above-described embodiment, the test bearing is exposed to water to supply moisture to the inside of the bearing. However, the test bearing can be exposed to a water vapor atmosphere, or water can be put inside the bearing in advance.

  In the above-described embodiment, 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. A thrust load can also be applied to these test bearings.

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 9 Hollow part

Claims (6)

  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 energization means for passing a current through the rolling elements is provided between an inner ring and an outer ring of the test bearing, and moisture is contained in the test bearing. A bearing test apparatus characterized by that   The energizing means supports the rotating shaft at a position away from the test bearing, and provides a dummy bearing in which inner and outer rings and rolling elements are formed of a conductor. The outer ring of the dummy bearing is used as the outer ring of the test bearing. It is fixed to another housing that is insulated from the fixed housing, the housings of these test bearings and dummy bearings and the rotating shaft are formed of conductors, and electricity is passed between the housings of the test bearings and dummy bearings. The bearing test apparatus according to claim 1.   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, wherein a load is applied.   The bearing test apparatus according to any one of claims 1 to 3, wherein the rotation driving means can apply a rotation cycle that repeats acceleration and deceleration.   The ratio P / C between the dynamic equivalent load P loaded on the test bearing by the load loading means and the basic dynamic load rating C of the test bearing is set to 0.05 or more. 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, water is supplied to the inside of the test bearing while the current is passed between the inner ring and the outer ring of the test bearing via the rolling elements, and the rotary shaft is driven to rotate. A bearing test method characterized by the above.

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