| 摘要 |
PURPOSE:To eliminate a drilling operation for a start point by providing a notch to a backing strip, bringing the notched surface into contact with a metallic plate to be cut and using the space part formed by the notch and the metallic plate as the start point for underwater gas cutting. CONSTITUTION:The engaging surface 7a of a backing plate 7 formed preliminarily with a notch 6 is pressed to the end face of a metallic plate 4 and the top surfaces of the plates 4, 7 are disposed flush with each other in the stage of cutting the plate 4 with gas in the water. The notch 6 is then used as a hole for starting cutting and a flame 2 is ejected from a torch 3 toward the notch 6 and at the same time an air curtain 1 is formed around the top end of the notch 6. Water is thereby thoroughly expelled from the inside of the notch 6 and when the torch 3 is moved in the direction X in this state, a cut part 5 is formed to the plate 4 and the underwater gas cutting progresses. The underwater gas cutting is thus accomplished without forming specially a hole for the start point to the metallic plate to be cut. |
