# US 4,396,798 A · High tensile strength suspension insulators with multi-step embedded pins

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- Number: US 4,396,798 A
- Document ID: US4396798A
- Status: Granted
- Kind: A
- Application number: 06/311,951
- Filed: 1981-10-16
- Granted: 1983-08-02
- Earliest claimed: 1980-10-22
- Assignees: NGK Insulators, Ltd.
- Inventors: Hiroshi Nozaki; Haruo Inoue
- Web page: https://patentgrep.com/patent/US4396798A

## CPC

- H01B 17/08: by cap-and-bolt
- H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K})

## Abstract

The suspension insulator of the present invention has an improved shape of the embedding portion of a metal pin, which is an embedding multi-step portion constructed with an inverted spherical convex trapezoid upper expanded portion having a larger surface at the top end and an inverted frust-conical lower expanded portion succeeding to the upper expanded portion. By using such a metal pin, the stress distribution of the insulating body is made uniform and therefore a small size and light weight of suspension insulator having high tensile strength is obtained.

## Claims

### Claim 1

In a suspension insulator in which an embedding portion provided at a top end of a metal pin is embedded in and secured to a pin assembling hole provided in an insulating body with a cement, the improvement comprising constructing said embedding portion with an inverted spherical convex trapezoid upper expanded portion having a larger surface at the top end and at least one inverted frusto-conical lower expanded portion succeeding to the upper expanded portion, wherein a curvature radius of a side surface of the inverted spherical convex trapezoid upper expanded portion is 40-80% of a diameter of said larger surface, and a taper angle .theta. of a side surface of the inverted frusto-conical lower expanded portion is 15.degree.-35.degree..

### Claim 2 (depends on 1)

The suspension insulator of claim 1, wherein said diameter of said larger surface is greater than a largest diameter of said frusto-conical lower expanded portion.