AU2013100975A4 - Improvements to Magnetic Earth Clamp - Google Patents

Abstract

Abstract Magnetic earth or ground clamps used to provide the earth connection for electric arc welding rely on a spring-loaded copper or brass electrode to carry the electric current to the job. It has been found in practice that in addition to the insulation described in Australian Patent 2005100632 further electrical insulation between the steel spring and the ferrite magnet element is also useful in preventing arcing in that section of the device. Such arcing may occur if the helical spring which is necessarily in contact with the electrode, makes contact with the magnetising ferrite or rare earth element in the device or if the space between the spring and the magnet element fills with iron filings or debris. Such arcing has been seen to burn out the spring or heat it sufficiently to destroy its temper. The present improvement describes means to provide such additional insulation to prevent such arcing and resulting damage. . . . . ........ . .... i ........... ................. ... ..... ..... ..... . . . . ... S South North

Description

EDITORIAL NOTE 2013100975 There is one page only of the description Brief Description of the Drawings FIG.1 is a simple cross-sectional illustration of a magnetic earth or ground clamp of the type well-known by those familiar with the art and having a ferromagnetic soft iron or steel housing Item A containing an annular magnetising element Item B of ferrite or rare earth material providing one magnetic pole at the extremity of the steel housing (Item A) and an opposite pole at the base of the annular magnetising element (Item B). Item C is the typically copper or brass current-carrying electrode and Item D is the typically helical spring providing contact pressure of the electrode onto the steel surface to which the device clamps. Item E is the insulator described in Patent 2005100632 FIG.2 shows a section through the intended improved clamp where Item H is a cup-shaped device of electrical insulating material having an outer annular wall Item J which may preferably be bonded at points Item K to the steel housing and/or the inner diameter of the annular magnetising element at points L. Item M is an optional inner annular ring forming part of Item H and in which the electrode Item C slides up and down.

Claims (5)

1. In a welding earth (ground) clamp of the magnetic type in which the current-carrying electrode passes through a spring and the magnet housing with an annular magnetising element a cup-shaped device of electrical insulating material having a central hole through which said electrode passes and a flat base on which the base of the said spring may rest.

2. In a welding earth (ground) clamp as described in Claim 1 a cup-shaped device of electrical insulating material having an outer perpendicular wall of such outside diameter that it provides a slide fit within the inner diameter of the annular magnetising element.

3. In a welding earth (ground) clamp as described in Claims 1 and 2 a cup-shaped device of electrical insulating material having optionally an inner perpendicular wall forming a cylinder in which said electrode may slide.

4. A welding earth (ground) clamp as described in Claims 1 to 3 wherein the said cup shaped electrical insulator is bonded to either or both the inner diameter of the magnetising element and/or the underside of the steel cup that houses the magnetising element.

5. A welding earth (ground) clamp as described in Claims 1 to 4 wherein the described cup shaped electrical insulator is preferably of plastic material being free-working and also having high electrical insulating properties such as Delrin or similar material.