Measuring and testing – Specimen stress or strain – or testing by stress or strain... – By loading of specimen
Reexamination Certificate
1998-12-30
2001-02-20
Noori, Max (Department: 2855)
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
By loading of specimen
C073S862080
Reexamination Certificate
active
06189387
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of detecting an overcoating rubber flowed in a space between a core member and a securing metal fitting of a polymer insulator having the core member, the overcoating arranged around the core member and the securing metal fitting fixed to at least one end of the core member.
2. Description of the Related Art
Generally, there is known a polymer insulator comprising a core member, overcoating arranged around the core member, and securing metal fitting fixed to at least one end of the core member. In order to keep a seal performance between the securing metal fitting and the overcoating, when such a polymer insulator is manufactured, the applicant proposed, in Japanese Patent Application No. 9-56297, a method of manufacturing the polymer insulator, in which an overcoating rubber for forming the overcoating is formed under a condition such that the securing metal fitting is set to the core member without being fixed, the securing metal fitting and the overcoating rubber are preliminarily cured, and the securing metal fitting is clamped to the core member.
In the manufacturing method mentioned above, since the securing metal fitting is simply set to the core member, in the case of forming the overcoating rubber, a V-packing is arranged in the space between the core member and the securing metal fitting, thereby preventing a flow of the overcoating rubber into the space. However, if the overcoating rubber should flow into the space between the core member and the securing metal fitting, the tensile strength of the polymer insulator is decreased. Therefore, it is necessary to detect whether the overcoating rubber has flowed into the space or not by a non-destructive manner.
As a non-destructive detection methods, there are X-rays, an ultrasonic flaw detection method, a method using acoustic emission, and so on. However, in the case of detecting whether or not the overcoating rubber which is flowed into the space between the core member and the securing metal fitting, as existent, it is not possible to detect the overcoating rubber in the space by the method of using X-ray, the ultrasonic flaw detection method and the method of using acoustic emission.
SUMMARY OF THE INVENTION
It is an object of the present invention to eliminate the drawbacks mentioned above and to provide a method of detecting an overcoating rubber of a polymer insulator which can detect whether or not the overcoating rubber is existent in a space between a securing metal fitting and a core member of the polymer insulator.
According to the present invention, a method of detecting an overcoating rubber flowed in a space between a core member and a securing metal fitting of a polymer insulator having the core member, the overcoating arranged around the core member and the securing metal fitting fixed to at least one end of the core member, comprises the steps of: applying a torque in a circumferential direction to the securing metal fitting, after forming the overcoating rubber but before fixing the securing metal fitting to the core member; deforming an index provided on a surface of the overcoating; and detecting whether the overcoating rubber is existent or not in the space between the securing metal member and the core member in response to a deforming extent indicated by the index.
In the present invention, a torque is applied in a circumferential direction to the securing metal fitting, after forming the overcoating rubber but before fixing to the securing metal fitting to the core member. Therefore, the index provided on a surface of the overcoating, which is preferably the parting line generated on a surface of the overcoating during forming, is deformed, and thus it is possible to detect whether the overcoating rubber is existent or not in the space between the securing metal member and the core member in response to the deforming extent indicated by the index. In this detection method mentioned above, since it is not necessary to use so much equipment for detection and it is performed in an easy manner, it is possible to perform the detection of whether or not the overcoating is existent in the space between the core member and the securing metal fitting easily even in a manufacturing field.
Moreover, in a preferred embodiment if torques rotating in a reverse direction with each other are applied to the securing metal fittings, which are arranged at both ends of the core member, it is possible to detect the overcoating rubber simultaneously at both ends. Preferably, if the deforming extent indicated by the index is measured by detecting a deforming amount in a circumferential direction between two points on the parting line with a predetermined distance, one of which is preferably set at a position at which the parting line and the securing metal fitting are contacted, and defining the detected deforming amount between two points as the deforming extent indicated by the index, it is possible to measure the deforming extent correctly.
REFERENCES:
patent: 5059486 (1991-10-01), Maronian et al.
patent: 5093203 (1992-03-01), Mowrey et al.
patent: 5162156 (1992-11-01), Troughton, Jr. et al.
patent: 5804299 (1998-09-01), Nakata et al.
Suzuki Tomio
Tani Takao
Burr & Brown
NGK Insulators Ltd.
Noori Max
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