Thermal Drilling with Force-Feed Tool

To reach the sufficient strength of threaded connection it is necessary to make 3 or more turns of the thread. In bars with the thickness of less than 2 mm the length of screwing is reached by sheet bending, connection pressing, cold stamping and other ways, which demand time requirements, additional operations, technical equipment, workforce. The article shows the way of making thread holes by rotating the punch in sheet blanks. There are five steps of the process being held. The following steps of forming holes are used these ways: with constant load and forced feed. The influence of bar thickness and forced feed on geometry of flanging: height and thickness of upper and lower extracting bases has been considered. The experimental data suggest that reducing the bar thickness, the height and thickness of upper and lower flanging bases. Herewith on bars with 5 mm thickness upper extracting is not being formed. Feed increasing causes reduction of height and increase in thickness of the upper and lower flanging. It can be seen on bars with all kinds of thickness (0,5...2,0 mm). The calculated and actual strength of the gained threaded connection on slice is submitted. Also it is clear that the actual strength of the gained threaded connection is higher than the calculated one, because of increasing micro hardness in the threading zone. The result of micro hardness measuring is assumed. To indentify the opportunity of using this method in industry the field of dissipation of the gained diameter was spotted in comparison with the limits by GOST 16093-2004. Also the gained hole corresponds to the 7th limit of accuracy of the inner thread diameter, what allows using this method in the industry [1-7]. (C) 2017 The Authors. Published by Elsevier Ltd.