Research the process of cold punching of hex nut blanks of increased height

Abstract

The high nuts withstand increased load for expansion, facilitating its even distribution along the bolt length. The process of increased height nut blanks plastic deformation characterized by uneven metal flow and changing of stressed state by the blank section. In the process of closed-die stamping of such nuts a risk of their geometry distortion arises. Results of study of the process of production a hex nut of increased height presented. The object of the research was to study the process of the metal deformation when broach a hole for thread in a hexagonal nut blank of increased height. To simulate the stress-strain state, the QForm-3D software package was chosen, which made it possible to predict with sufficient accuracy the metal flow in the blank, calculate the deformation forces and determine the stresses that occur in the tool. The models of the blank and the tool were created in the Compass 3D program without internal and external defects. When performing the work, the parameters of the stress-strain state of a hexagonal nut blank of increased height were calculated. The simulation results showed the need to change the geometry of the end part of the punch to a conical one with an angle of 150 degrees and a reduction in the size of the baffle height from 10.4 mm to 5.4 mm. The adopted changes allowed to reduce the energy and power costs of forming a through hole for the threads. Industrial testing confirmed the correctness of the calculations. Nuts with edges perpendicular to its base and the required geometrical parameters were obtained.