Analysis of the Surface Roughness of a Tube Drawn by a Fixed Mandrel

Abstract

The manufacture of tubes by a fixed mandrel drawing is one of the technologies in the manufacture of seamless tubes. This is the oldest tube drawing method. It uses a mandrel at the end of the die to shape the internal diameter of the tube. This process is slow and the area reductions are limited (lengths of tubes are limited), but it gives the best inner surface finish of any of the processes. The use of a fixed mandrel by the drawing of small-diameter tubes makes it possible to increase the accuracy of the inner surface and improve the quality. The paper presents the results of solving a partial task in this area. It deals with the reconstruction of the microgeometry of the inner surface of a tube drawn by a fixed mandrel. Tubes (STN 41 1353) were drawn through dies with different reduction angles. There were grounds the straight and spiral grooves on used fixed mandrels. On the inner surface of the tube were formed grooves after drawn that had a different surface roughness compared to the mandrel surface. The paper graphically presents the morphology of obtained surfaces under various conditions (reduction angles, straight/spiral grooves on the fixed mandrel) as well as measured surface roughness values. At the end of the paper, the knowledge gained through experimental research are summarized.

Stability analysis of roundness profiles of drawn tubes

“…[2,3] The profiles of drawing die orifice and the mandrel are key factors to achieve the requirements of tube geometric precision and the surface roughness. [4] The circular and cylindrical features are fundamental geometric features in machines. The fitting conditions of cylindrical components have a significant effect on the performance of precision products, and they are determined by size tolerances and geometrical errors such as cylindricity error of the mating parts.…”