Electric heating – Metal heating – By arc
Patent
1987-05-15
1989-06-27
Shaw, Clifford C.
Electric heating
Metal heating
By arc
219 68, 439 5, B23K 900
Patent
active
048421545
DESCRIPTION:
BRIEF SUMMARY
This invention is directed to an apparatus for underwater working, especially for heating, welding, torch cutting, cleaning and electrolyte coating of metal constructions with the aid of electric current. The apparatus consists of an electrically conductive rotatable shaft which is arranged on a frame element. The shaft conducts electric current to a removable tip element, which is attached to the end of the shaft and rotates therewith the tip can be a heating bushing, welding electrode, cutting, cleaning and/or coating disk.
It has been previously known to use in this type of apparatus different electric terminals and carbon arrangements to conduct necessary electric current to the rotating shaft. These prior devices however cannot be used in great depths of water due to insufficient compensation for hydraulic water pressure.
Attempts have been made to solve this problem through massive frame constructions and complicated sealing systems that would stand the high external pressure. Such prior devices are, however, expensive and rather difficult to handle because of their great size and weight. As a result of non-existing or defective pressure compensation, water leaks into the tool causing failure. Sometimes the casing of the frame part literally breaks down.
An additional disadvantage of existing tools is that they need, without exception, a ground wire connected with the "-" pole of the power source in order to create a flame arc. This aspect will essentially limit the applications of the apparatus and makes it nearly impossible to use it as a tool in driving robots or remote controlled equipment. As the work usually requires driver's help, it is obvious that to use such equipment is slow and expensive and involves safety hazards.
The purpose of the present invention is to eliminate the disadvantages and weak points found in existing devices, and to produce an apparatus for underwater work which is lighter, more reliable and easier to use.
According to the invention, the means of electrical conductance provides both conduction of electricity and also compensation of hydraulic water pressure. Another advantage is that ground current may be conducted through the rotable shaft, which means that the flame arc can be created exactly where it is needed without any clumsy separately connected ground wires. Thus, the apparatus according to the invention is simple to use and especially suitable for use in diving robots and other remote controlled equipment. In the present apparatus, the pressure is essentially the same inside and outside the frame element, therefore, the hydraulic water pressure may thus be rather high without presenting any significant problem, and it is possible to use a relatively simple and less expensive design for the frame element.
In the following, the invention is described with reference made to the enclosed drawing showing a side cross section of a presently preferred embodiment of the apparatus according to the invention. This illustrated apparatus functions as a cutting tool.
In the drawing, reference number 1 refers generally to the frame element which consists of several units joined together, by means of a bolt B. A rotating, two-piece electrically conductive shaft 2 is journalled on bearings carried by the shaft.
The shaft 2 comprises two shaft elements 21 and 22 nested within each other to form a unitary rotating shaft. Shaft elements 21 and 22 have been electrically insulated from each other by arranging an electrically insulating intermediate element 23 between their opposite faces. The intermediate element 23 is a sleeve made of rubber or plastic-based material. Also, the profiles of the opposite faces of the shaft elements 21 and 22 are designed to prevent rotation of the shaft elements in relation to each other. Suitable profiles are any forms except round ones, for instance, the outer shaft element 21 may be a tubular shaft with a central polygonal cavity while the outer circumference of the inner shaft element 22 is formed to correspond to the form of the outer tubular s
REFERENCES:
patent: 3078432 (1963-02-01), Kenyon
patent: 3338808 (1967-08-01), Johnson
patent: 3663787 (1972-05-01), Haswell, III et al.
patent: 3681633 (1972-08-01), McNab
patent: 4151455 (1979-04-01), Janotik
patent: 4566744 (1986-01-01), Engelenburg et al.
Oy GSS General Sea Safety Ltd.
Shaw Clifford C.
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