GB1074958A - Process and mill for rolling hollow bodies - Google Patents

Abstract

1,074,958. Rolling seamless tubes. CONTUBIND SOC. ANON, and LORRAINE-ESCAUT SOC. ANON. Sept. 13, 1965 [Sept. 9, 1964], No. 36988/64. Heading B3M. A seamless tube is produced by passing a heated hollow blank 6, Fig. 1, through roll stands 1-5, advancing a tapered mandrel 9 down the blank bore at a controlled speed in the direction of rolling, and forcing lubricant through a duct in the mandrel, and laterally out through at least one opening in the mandrel, to an annular space between the mandrel and the blank. The mandrel 9 is carried on a carriage 7, Fig. 1, which is moved by a fluid pressure cylinder 8. Double acting hydraulic pistons 13 are connected by a crosshead 14 and when the carriage 7 abuts the crosshead, the feed of the mandrel is controlled at a slow rate by the fluid escape from cylinders 12. The mandrel 9, Fig. 1, and Figs. 5-6 (not shown), comprises a tubular body 17 closed at its front end, a concentric pipe (18) connected to a drain hose 19, and a second concentric pipe (20). The annular space between the front end of the pipes is closed by a seal (21) and the space at the rear end is connected to a flexible hose 24. The passage between the outer pipe and the mandrel, is connected at its rear end to a flexible hose 22. Cooling waste for the mandrel is supplied by hose 22 between the outer pipe and mandrel, to the front end, and then back through pipe (18) to drain hose 19. Valves (26) are provided in the mandrel, and connect the space between pipes (18) and (20) to the space between the mandrel and the blank. During rolling, lubricant is supplied by hose 24, and as a valve (26) comes into contact with the bore of blank 6, it is depressed inwardly, and lubricant passes through the valve. When the tube leaves stand 5 it is supported on a run-out table 31 and is stripped from the mandrel by stripper plates 32. Lubricant.-The lubricant may be a mixture of graphite, wood sawdust and heavy oil, or graphite, wood sawdust and waste grease, or may be mineral salt, borax, specific glass powder, silicates or metal oxides. The outer surface of the mandrel may be chrome-plated, or may have a ceramic or plastic coating thereon. Through the initial combustion, a later decomposition of the oil in the lubricant a gas current is formed, that flows across the mandrel, and removes the scale on the blank. In a modification, the tapered mandrel (40), Figs. 7-10 (not shown), comprises an outer tube having lubricant outlets (44) connected to a space formed between a pipe (45) and the tube. The inside wall of the blank will not be descaled by a gas current, but the scale is made innocuous by introducing mineral salt, borax, or coal dust into blank before being charged into the mill. During rolling, cooling water is introduced into the rear end of the passage between pipes (45), (46) and it flows back through the bore of pipe (46) to drain. In a further modification, mandrel (55), Figs. 11, 12 (not shown), has a normally closed valve (59) as its front end, and during rolling, the mandrel is filled with cooling water. After the rolling operation is completed, the water pressure is increased so as to open the valve and exhaust the water.