Blockage mechanism of metal wire in semi-dieless drawing and stable forming method

Abstract

Blockage easily happens during semi-dieless drawing, in which die drawing follows dieless drawings, under constant feeding speed mode. In this paper, the blockage mechanism is first studied, and then variable feeding speed mode is proposed to solve the problem. Experiments of semi-dieless drawing under the constant and the variable feeding speed modes are performed at different area reduction of die drawing, while the total area reductions are kept the same as 33%. Variation of wire diameter at die entry is measured. Results show that the area reduction of die drawing increases gradually, in the meanwhile that of dieless drawing decreases gradually under the constant feeding speed mode. This could result in formation of multiple transition sections of wire diameter, the number of which depends on the area reduction of die drawing. Eventually, semi-dieless drawing deteriorates into die drawing, resulting in the blockage when the area reduction exceeds equipment's capacity. The variable feeding speed mode only allows the formation of one transition section, which avoids the blockage. Continuous and stable semi-dieless drawing with 33% total area reduction is realized under the variable feeding speed mode.