Mathematical Model of Energy Processes in an Industrial Electric Screwdriver

Abstract

An electric screwdriver was designed to work in an automatic cycle on assembly lines. A characteristic feature of the screwdriver is the use of a low power motor in comparison with commonly used devices. The work of tightening the threaded joint takes place at the expense of the kinetic energy of the components of the drive system and the working screwdriver. It has been proved that the ability of the screwdriver to perform the tightening work is determined by the sum of the mass moment of inertia of the working components system and the mass moment of inertia of the motor's rotor, reduced to the axis of the screwdriver bit. The process of tightening is characterized by the number of screwing pulses, screwing torque values at the end of each pulse and the time of screwing process. The limitation of the value of the transmitted tightening torque takes place through the applied overload coupling.  The construction work of the screwdriver was preceded by the development of a mathematical model of the process of screwing and balance of torques acting during each phase of operation was carried out. This allowed the calculation of the value of the kinetic energy of components of the drive and operating system translated into the tightening work. The kinematic conditions to be met by the screwdriver at the end of a single tightening pulse were determined in order to accumulate kinetic energy and start another tightening pulse.