JPH07120370A - Degradation diagnostic method for electric-wire insulator - Google Patents

Abstract

PURPOSE:To simply form a test piece and to surely and quickly judge its degradation, regarding the degradation diagnostic method for an electric-wire insulator, which judges the degradation of an insulator with which an electric wire is coated. CONSTITUTION:A test piece 5 is placed on a stage 4 of a compression testing machine P, an electric-wire insulator as the test pieces 5 is pushed in at a definite speed by an indenter 2 of the compression testing machine P, and the hardness of the electric-wire insulator is evaluated on the basis of a pushed-in depth at a time when the load reaches a prescribed value. Then, the hardness of samples in which various degradations have been caused, is compared with the hardness of the electric-wire insulator, and the degradation state of the electric-wire insulator as the test piece 5 is diagnosed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for diagnosing deterioration of an electric wire insulator for judging deterioration of an insulator covering an electric wire.

[0002]

2. Description of the Related Art Conventionally, J has been used as a test method for electric wire insulators.
Various test methods are specified in IS C3005, and there is a description regarding a tensile test method for an insulator in the test methods.
In this test method, as shown in FIG. 4, the electric wire was cut into 150 mm, all the internal conductors were drawn out, and a sample s was prepared by drawing marked lines a and a ′ at intervals of 50 mm in the center. Both ends of the sample are fixed to the grips b and b '. Then, the sample s is pulled at a speed of 200 mm / min, and the elongation of the interval between the marked lines when the sample s breaks is measured, and the percentage from the initial point is taken and expressed by the elongation rate.

However, according to the above method, in the case of an electric wire or the like near the end of a connector where heat is locally deteriorated due to the influence of a heating element, the portion that is most thermally deteriorated is sandwiched between the grips of the tester. However, there is a basic defect that the deterioration diagnosis of this part cannot be performed. Moreover, the conductor in the electric wire has to be pulled out to prepare a test piece, which requires a lot of time for the measurement work.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is a method for diagnosing deterioration of an electric wire insulator in which a test piece can be easily prepared and deterioration can be determined surely and quickly. The challenge is to provide.

[0005]

In order to achieve the above object, the present invention places a test piece having an electric wire insulator on a stage of a compression tester, and compresses the electric wire insulator of the test piece. Pushing at a constant speed by the indenter of the testing machine, the hardness of the electric wire insulator is evaluated by the pushing depth when a predetermined load is reached, and the hardness obtained in advance for various deteriorated samples, and It is characterized in that the deterioration state of the electric wire insulator is determined by comparing the hardness of the electric wire insulator.

[0006]

According to the present invention, when measuring the hardness of an electric wire insulator for diagnosing deterioration, there is no restriction on the shape of the test piece, so that the product can be diagnosed as it is and the test piece can be easily prepared. At the same time, since a small amount of test piece is required, local deterioration of the insulator can be diagnosed. In addition, by preparing in advance samples of various materials and their progress of deterioration, it is possible to make a quick comparison and make a diagnosis.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory diagram of a compression tester P according to an embodiment of the present invention. The compression tester P includes a strain gauge type load cell 1, an indenter 2 attached to the tip of the load cell 1, a differential transformer 3, a stage 4 and the like, and a test piece having an electric wire insulator on the stage 4. 5 is placed, the indenter 2 is pushed into the electric wire insulator of the test piece 5, the load at that time is measured by the load cell 1, and the pushing depth is measured by the differential transformer 3 to measure the test piece 5 The hardness of the wire insulation is evaluated.

A method for diagnosing the deterioration state of the test piece 5 by using the above compression tester P to collect the test piece 5 from the electric wire near the connector and the terminal of the actually used wire harness will be described. The electric wires that compose this wire harness are so-called covered electric wires in which the periphery of the core wire is covered with an electric wire insulator.

The collected test piece 5 is placed and fixed on the stage 4 in a product state. The indenter 2 is attached to a predetermined portion of the test piece 5.
Is positioned and is pushed in the vertical direction at a constant speed of 0.5 mm / min, and the hardness of the insulator of the test piece 5 is determined by the pushing depth at the time when the load value preset to the load cell 1 is reached. Since the hardness of a specific insulator is closely related to the deterioration of the insulator, the hardness of the insulator sample that has been caused various kinds of deterioration by a bench test or the like is measured beforehand. It is possible to determine the deterioration state of the test piece by its hardness.

For example, FIG. 2 shows an initial product, a product A recovered from the market.
(Test product 100 mm away from the crimping part with the terminal), market recovery product B (test product 5 mm away from the crimping part with the terminal), and 200 hours in a thermostatic chamber set to 100 ° C as a sample It is a graph of the hardness measured about four types of test pieces of the bench test product left to stand.

It can be seen that the bench test product, the market-recovered product A, and the market-recovered product B all have a smaller indentation depth under each load than the initial product, and that deterioration is progressing. In particular, the market-recovered product B near the crimping part of the terminal
It is shown that the indentation depth is the smallest and that local hardening occurs due to thermal deterioration, and it is clearly diagnosed that the deterioration is severe.

FIG. 3 is a graph showing the relationship between the elongation rate of the insulator and the indentation depth. The vertical axis represents (indentation depth h) ^-2 and the horizontal axis represents the elongation rate% of the insulator. It is shown. In this way, the relationship between the elongation rate of the insulator and the indentation depth is obtained in advance, and by comparing it with the value of the test piece taken in the actual environment, the deterioration state in the actual environment can be accurately determined. It becomes possible to diagnose.

[0013]

According to the present invention, since there is no restriction on the shape of the test piece to be measured, the test piece can be diagnosed as it is, the test piece can be easily prepared, the efficiency of the diagnostic work is improved, and the test piece can be manufactured in a small amount. Therefore, the local deterioration of the insulator can be diagnosed, and the detailed diagnosis in the actual usage state of the DUT can be performed. In addition, by preparing in advance the characteristics of various materials and the characteristics of the specimen according to the degree of deterioration thereof and comparing them with the results of the test piece, there is an excellent advantage that a diagnosis can be made quickly.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a compression tester according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between hardness and load of a test piece obtained by the compression tester of FIG.

FIG. 3 is a graph showing the relationship between the indentation depth and the elongation rate of FIG.

FIG. 4 is an explanatory view of a test piece used for a tensile test of a conventional electric wire insulator.

[Explanation of symbols]

 P compression tester 2 indenter 4 stage 5 test piece

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[Procedure amendment]

[Submission date] July 29, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

FIG. 3 is a graph showing the relationship between the indentation depth and the elongation of the test piece obtained by the compression tester of FIG.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (1)

[Claims] 1. A test piece having an electric wire insulator is placed on a stage of a compression tester, and the wire insulator of the test piece is pressed at a constant speed by an indenter of the compression tester to a predetermined load. The hardness of the electric wire insulator is evaluated by the indentation depth when reaching, and the hardness of the electric wire insulator is compared with the hardness obtained in advance for samples with various deteriorations, thereby A method for diagnosing deterioration of an electric wire insulator, which comprises determining a deterioration state.