Union Carbide Canada Limited

John William Ross

Pertti T Raty

This invention provides an improved method for employing a plasma-arc cutting torch to cut a metal plate. The improvement consists in operating the torch with its lower portion submerged in a layer of water provided over the workpiece. In order to allow automatic adjustment of the torch to the appropriate working height above the workpiece, a mechanism is provided for mounting the torch with respect to the support carriage which guides its horizontal path. This mounting mechanism is such as to allow relative up and down movement between the torch and the support carriage and includes a detecting mechanism including a frame and vertical slides on which the cutting torch is secured so that when the mounting mechanism is lowered to the point where the torch touches the metal plate, the detecting mechanism communicates a signal for the upward movement of the mounting mechanism thereby raising the torch to a predetermined cutting distance from the metal plate.

Torch support and height sensor apparatus for shape cutting machines

An apparatus and method of freezing a large volume of ground for tunnel construction and the like utilizing liquified nitrogen is described. The apparatus consists generally of a series of freeze pipes embedded in the ground, each of the freeze pipes consisting of a conductor tube and an inner header tube. The header tube of each of the succeeding freeze pipes in the series have discharge holes of a predetermined cross-section so that greater control of gaseous and liquified nitrogen pressure can be maintained throughout the system. By means of this method and apparatus more accurate control of ground freezing can be made by merely controlling the inlet liquified nitrogen pressure and the exhaust gaseous nitrogen temperature.

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Toronto, Canada

John William Ross