GB538569A - Improvements in methods and apparatus for the removal of scale from the surface of metal bodies - Google Patents

Abstract

538,569. Blowpipe burners. LINDE AIR PRODUCTS CO. Feb. 1, 1940, No. 1949. Convention date, March 3, 1939. [Class 75 (i)] [Also in Group II] Scale is removed from ferrous metal by surface heating by flames, which causes differential expansion between the upper and lower surfaces of the scale. The heat is derived from a burner H mounted on a wheeled carriage C adapted to be moved over a surface of a billet B to be treated. An oxyacetylene mixture is supplied by a blowpipe 22 having controlling valves 27, 28 and a shut-off lever valve 29. The wheels W are adjustably mounted by clamps 31 on frame members 32. Skids 36 of refractory material are mounted adjacent to the burner H, to space the burner about # inch from the surface. The burner comprises a solid block 40 containing passages for combustible mixture, and a lower strip 41 with long outlet passages 42, partly conical at 44 and partly cylindrical at 45. High-temperature flames are obtained by preheating in the passages of the block 40 and by providing an oxygen-acetylene ratio of 1.5 to 2:1. The mixture issues from the passages with a velocity between 600 feet per second and the velocity of flame propagation. Burners similar to H may be provided to direct flames against each of the four sides of a billet. If a cylinder or tube is to be treated, the burner may be stationary with the row of flames directed on a longitudinal portion of the surface while the cylinder or tube is rotated, or the burner may be curved to cover part or all of the circumference. Fig. 13 illustrates a semi-circular burner comprising an outer block 70, and an inner block 71 having outlets 42'. A baffle 72 perforated at 73 is arranged in the space between the two blocks. The burner is maintained at the correct distance from the surface S' by skids 36<SP>1</SP>. The cylinder R is moved longitudinally to remove scale from half its surface, and is turned through 180 degrees and the operation repeated. In another modification applicable for treating interior surfaces, the burner may be provided with slots 85, Fig. 16, whereby extra air is supplied for secondary combustion and to remove scale. Cooling water may be circulated through passages 88, 89. Separate air jets may be provided to remove scale, Figs. 17, 18 (not shown), or alternatively, electromagnetic means as in Fig. 19. Endless belts 100 with cross bars 104 are provided above the treated surfaces, and electromagnets 103 are arranged to draw the loosened scale on to the belts which carry it to a position where it drops off clear of the apparatus. The apparatus of Fig. 1 may be used for treating very thick scale by melting a series of closely adjacent holes in it in strips, after which the intervening strips can be detached mechanically.