Wire rope flaw detector

Abstract

A wire rope flaw detector comprises a back yoke (3) and excitation permanent magnets (4a, 4b), which form a main magnetic path in a predetermined section of a wire rope (1) in the axial direction; a magnetic path member (7) arranged in the predetermined section to be magnetically insulated from the back yoke (3) and the permanent magnets (4a, 4b) and making the leakage flux generated from a damaged part (10) of wire rope detour to the outside of the wire rope (1); and a detection coil (8) wound around the magnetic path member (7) for detecting leakage flux. The amount of leakage flux can be increased by providing the magnetic path member (7) and since the windable area of the detection coil (8) is increased, the number of turns of detection coil can be increased.

Description

technical field [0001] The present invention relates to a wire rope flaw detection device for detecting breakage of a wire rope suspending a car of an elevator or the like and a broken wire of a single strand (hereinafter referred to as a damaged part of the wire rope). Background technique [0002] Conventionally, as a wire rope flaw detection device, there is a wire rope flaw detection device that uses a detection coil to detect leakage magnetic flux generated in a damaged portion such as a single strand break when the wire rope is magnetically saturated, and detects the damaged portion of the wire rope (for example, refer to Patent Document 1). [0003] In addition, in the past, there is also the following magnetic flaw detection device for steel wire ropes. The magnetic flaw detection device for steel wire ropes has an excitation core, an excitation coil, a power supply, and a detection coil. The excitation core has at least two magnetic poles that are relatively close to...

AI Technical Summary

Problems solved by technology

Therefore, when damage occurs inside the wire rope, the influence on the cross-sectional area of ​​the magnetic circuit is reduced, and there is no difference in magnetic permeability, so it is difficult to detect the damage.

[0009] Furthermore, in the method of Patent Document 2 (JP-A-11-230945), there is a possibility that the detection accuracy may decrease when a plurality of damaged parts are generated close to the longitudinal direction of the wire rope.

For example, in the case where a damage of the same degree occurs in each of the two specified detection intervals, since the difference in the magnetic permeability of the two detection intervals is reduced, the induced voltage generated on the detection coil is reduced, and the SN ratio is reduced.

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