JP2016024090A - Crack detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crack detecting method that can accurately detect the time range in which a crack occurred.SOLUTION: In a crack detecting method for detecting any crack occurring in any constituent part of a rolling bearing under impact test, an electro-conductive member 10 having an electro-conductive layer whose electric resistance varies with the occurrence or growth of a crack and an insulating base layer that insulates the electro-conductive layer from the surface of the constituent element is arranged on the inner circumferential face of a holder 1. By causing an electric current to flow through the electro-conductive layer and measuring the electrified state of the electro-conductive layer, the occurrence of any crack is detected.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a crack detection method.

  For railway vehicle bearings, steel bearings, construction machinery bearings, etc. used under conditions subject to vibration, it is essential to conduct an impact test to confirm that the design is appropriate.

  For example, in Patent Document 1, a shaft in which an inner ring of a rolling bearing with a cage is mounted, a housing in which an outer ring of the rolling bearing is mounted, and a unit in which the shaft is supported on the housing by the rolling bearing are assembled. A cage strength evaluation test device is disclosed that includes a drive device that rotates the shaft, and a load generator that applies vibration or impact to the unit while the shaft is rotated by the drive device.

JP 2008-64730 A

  In the cage drop impact test conducted with the bearing assembled, it cannot be confirmed during the test that the cage is made of tortoise, so it is impossible to accurately grasp when the crack has occurred. For this reason, the test is interrupted at regular intervals, and labor is required to disassemble the bearing and check the condition of the cage. Furthermore, in this case, there is a drawback that the detection accuracy of the crack generation time is affected by the decomposition frequency.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a crack detection method capable of accurately detecting the occurrence time of a crack.

The above object of the present invention can be achieved by the following constitution.
(1) A crack detection method for detecting a crack generated in a component of a rolling bearing under an impact test,
On the surface of the component part, a conductive member having a conductive layer whose electrical resistance is changed by generation or progress of a crack and an insulating base layer that insulates between the conductive layer and the surface of the component part is disposed. And
A crack detection method characterized by detecting the occurrence of a crack by passing an electric current through the conductive layer and measuring an energization state of the conductive layer.
(2) The conductive member is disposed on the surface of the component by being applied,
(1) The crack detection method according to (1), wherein the application shape of the conductive member is a single stroke or a plurality of linear shapes.
(3) The crack detection method according to (1) or (2), wherein the breaking elongation of the conductive member is 30% or more.

  According to the crack detection device of the present invention, a crack is generated in a component of a rolling bearing under an impact test by passing an electric current through the conductive layer and measuring an energization state of the conductive layer. The timing can be accurately detected.

It is a perspective view of the holder | retainer which concerns on this embodiment.

  Hereinafter, a crack detection method according to an embodiment of the present invention will be described with reference to the drawings. In addition, although a cage is described as an example of a component of a rolling bearing, the present invention detects not only a crack generated in the cage but also a crack generated in a rolling bearing component such as an outer ring or an inner ring. It is also possible to apply to. Also, the type of cage is not particularly limited.

  As shown in FIG. 1, the cage 1 in which the occurrence of a crack is detected by the crack detection method of the present embodiment includes a small diameter annular portion 3, a large diameter annular portion 5, a small diameter annular portion 3, and a large diameter. The circular part 5 is connected, and is defined by a plurality of column parts 7 arranged at predetermined intervals in the circumferential direction, a small-diameter annular part 3, a large-diameter annular part 5, and a plurality of pillar parts 7. A tapered roller bearing retainer comprising a plurality of pocket portions 9 for accommodating rollers (not shown).

  Such a retainer 1 holds a plurality of tapered rollers in a rollable manner as components of a tapered roller bearing (not shown). The tapered roller bearing includes an outer ring, an inner ring, a plurality of tapered rollers disposed between the outer ring and the inner ring, and a cage 1 that holds the plurality of tapered rollers by a plurality of pocket portions 9.

  The cage 1 is subjected to an impact test and evaluated for strength while the tapered roller bearing is assembled. Examples of the impact test include a drop impact test.

  Here, it is desirable that the cage 1 can be accurately grasped during the impact test without disassembling the bearing. Therefore, the inner peripheral surface of the cage 1 of the present embodiment is provided with an insulating layer that insulates between the conductive layer whose electrical resistance changes due to the occurrence or development of a crack and the conductive layer and the inner peripheral surface of the cage 1. A conductive member 10 having a formation is disposed.

  The electroconductive member 10 is arrange | positioned by apply | coating to the internal peripheral surface of the holder | retainer 1, and is one line of one-stroke writing. More specifically, the conductive member 10 includes a plurality of large-diameter circumferentially extending portions 11 extending in the circumferential direction so as to connect adjacent column portions 7 on the large-diameter annular portion 5, and a large-diameter circumferential direction. A plurality of axially extending portions 12 extending in the axial direction on the column portion 7 and the adjacent axially extending portions 12 are connected to both ends in the circumferential direction of the extending portion 11, and on the small-diameter annular portion 3 And a plurality of small-diameter circumferentially extending portions 13 extending in the circumferential direction. That is, in a pair of adjacent pocket portions 9, a large-diameter circumferentially extending portion 11 is painted on the inner peripheral surface of the large-diameter annular portion 5 that defines one pocket portion 9, and the other pocket portion 9. A small-diameter circumferentially extending portion 13 is coated on the inner peripheral surface of the small-diameter annular portion 3 that defines the above, and an axially extending portion 12 is painted on the inner peripheral surfaces of all the column portions 7.

  Then, a current is caused to flow through the conductive layer of the conductive member 10 by an electrode (not shown), and the state of conduction of the conductive layer is measured, that is, the resistance value of the conductive layer is monitored. Detect the time. Therefore, unlike the prior art, it is not necessary to discontinue the test at regular intervals and disassemble the bearing, and it is possible to easily and accurately detect the occurrence time of the crack. Furthermore, since the application shape of the conductive member 10 is a one-stroke line, the output to the outside is only required in one place, which has the effect of simplifying the wiring.

  Here, in the crack detection under the drop impact test, it is necessary to perform the crack detection in an environment where the cage 1 is constantly repeatedly deformed by the impact. Therefore, the conductive member 10 does not break due to the elastic deformation due to the impact during the test, and needs to be broken only when the cage 1 is cracked. For this reason, in this embodiment, the breaking elongation of the conductive member 10 is set to 30% or more, which is a very high numerical value. Thereby, since the electroconductive member 10 does not fracture | rupture by the elastic deformation by the impact in a test, a misdetection can be prevented. On the other hand, when a crack occurs, the cage 1 is greatly opened due to the impact of the test, so that the conductive member 10 is broken and the crack can be properly detected. In addition, if the breaking elongation of the conductive member 10 is set to a range of 30% or more, even if it is a metal cage such as a steel cage and a brass cage, or a resin cage, it will crack. Detection can be performed accurately.

  In addition, this invention is not limited to embodiment mentioned above, A change, improvement, etc. are possible suitably.

  For example, in the above-described embodiment, the conductive member 10 is disposed on the inner circumferential surface of the cage 1, but may be disposed anywhere on the surface of the cage 1, for example, the outer circumferential surface or the shaft. You may arrange | position to a direction side surface.

  Moreover, the application | coating shape of the electroconductive member 10 is not limited to one line shape of one-stroke drawing, It is good also as a several line shape of one-stroke writing. That is, in addition to the single line-shaped conductive member 10 written on the inner peripheral surface of the cage 1 as in the present embodiment, the single line written on the outer peripheral surface of the cage 1. The conductive member 10 may be applied.

1 Cage (component)
3 Small-diameter annular portion 5 Large-diameter annular portion 7 Column portion 9 Pocket portion 10 Conductive member 11 Large-diameter circumferential extension portion 12 Axial extension portion 13 Small-diameter circumferential extension portion

Claims (3)

A crack detection method for detecting a crack generated in a component of a rolling bearing under an impact test,
On the surface of the component part, a conductive member having a conductive layer whose electrical resistance is changed by generation or progress of a crack and an insulating base layer that insulates between the conductive layer and the surface of the component part is disposed. And
A crack detection method characterized by detecting the occurrence of a crack by passing an electric current through the conductive layer and measuring an energization state of the conductive layer. The conductive member is disposed by being applied to the surface of the component,
The crack detection method according to claim 1, wherein the application shape of the conductive member is one or more lines drawn with a single stroke. The crack detection method according to claim 1, wherein the breaking elongation of the conductive member is 30% or more.

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