Abstract
The share of imports in the total amount of fasteners that were consumed in the Russian Federation in 2014 amounted to 46%. These mainly included bolts and screws. Expanding the output of fasteners with heads is an important task for the domestic industry. Better effi-ciency can be achieved in bolt production by improving the product design and adopting low-waste technologies. The purpose of this research is to develop a mathematical model for calculating the power parameters of the low-waste bolt socket head forging operation. The problem of defining the power parameters of the socket head forging process was solved with the help of the variational method. A model of the rigid-plastic environment with nonlinear hardening was used to define the rheological properties of the forged material. The exponential dependence was used to describe the hardening curve. The authors looked at the final stage of the deformation process when the tool movement is small during the final forging operation. The volume deformed during the final forging operation was divided into rigid and plastic regions. Displacement functions were set in and the functional description of the total deformation work was compiled. Numerical methods and a specially developed program were used to calculate the minimum of the total deformation work. Based on the results of the calculations, a nomogram was created that helped determine the specific socket head forging forces depending on the relative dimensions of the head and for the steel grades that are most commonly used in the bolt industry. The results of the research were used to develop low-waste technologies that were used to produce the pilot batches of M 16x50 socket head bolts (per GOST 7798-70) and ‘TsP-54’ socket head track screws (per TU 1293-165-0112432-2003). The application of the developed technologies can help save 3–6% of the metal.
Keywords
Bolt head forging, socket, variational method, displacement functions, power parameters, forging forces.
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