THE RESEARCH OF INFLUENCE SIZE STRAIN AND NUMBER OF DRAWS ON DIMENSIONAL ACCURACY OF SEAMLESS TUBES MADE OF STEEL E235 AND E355

Abstract

The die drawing process is used as a final drawing operation, especially in the production of precise tubes of smaller diameter, while the advantage of the mentioned technology is a reduction of the drawing force and thereby also the decrease of the risk of possible tube rupture during the drawing process. The paper is focused on the research of the influence of the strain size and the method drawing process on the final thickness of the wall and the outer diameter of the tube during die drawing. The sinking drawing experiment was performed by single-pass and two-pass drawing technology to the final tube diameter Ø12 mm without inter-operational annealing. The output of the paper are bar graphs that allows to compare the influence of the strain size and the method of tube drawing technology (single-pass and two-pass) on the dimensional accuracy of the final Ø12 mm tubes made of E235 and E355 steel. The advantage of the single-pass drawing technology when achieving the required wall thickness within the prescribed tolerance (±10 %) would be a reduction of the number of draws.It was found that only in one case of the two-pass drawing technology of E355 steel tube production, the permitted positive tolerance of the tube wall thickness was slightly exceeded, in the case of increasing the reduction (size strain R) from 24 % to 32 %.