MANUFACTURE AND DEVICE FOR THIN METALLIC TUBE

摘要

PURPOSE:To improve productive efficiency by rolling by preventing bulge with guide shoes which are provided among each roll when the metallic tubing with a large outside diameter into which a mandrel is inserted and which the ratio of the outside diameter D to the wall thickness (t) is a specified value into the metallic tube with a smaller outside diameter. CONSTITUTION:By drawing down the outside diameter and wall thickness spirally among three rolls 1 which are rotatively driven of a three roll mill and the mandrel 3, the metallic tubing 2 with a large outside diameter is made into a metallic tube 2' with a small outside diameter as product. At that time, because the thickness (t) of the metallic tubing 2 with a large outside diameter is thin and the ratio of the outside diameter D to the wall thickness D/t is > 12, the tubing is made so as to be greatly bulged into the spaces especially among the three rolls 1. But that bulge is prevented with guide shoes 7 which are provided among each roll and the formation of flare is restrained and the approximately cylindrical tube with a smaller outside diameter is made. In this way, productive efficiency can be improved without interrupting the flow of the process for manufacturing metallic tube.