Forming of tap holes by rotating punch made by force-fed in thin sheet workpieces

P. V. Shalamov, D. A. Saveliev, N. D. Mironova, J. V. Kazantseva

Abstract


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

Keywords


thin sheet workpiece; punch; connection; micro hardness; transmission set; force-fed

References


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