Control strategies for manipulating contact force of Impact Wrench to generate high level torque

Impact Wrench is one of power tools which have sophisticated structure to generate impact motion by using electrical motor or hydraulic actuators. In the system, an impacting module, which consists of impactor, spindle, connect balls, locker and spring, has an important role to generate impacting motion. In this paper, two strategies are investigated for improving performance to generate high level torque at an anvil. The motion equation of the system during impacting motion is derived and the control methodologies are proposed to manipulate contact force, sequentially. One of the proposed control methods is controlling the spring length by compressing on the opposite side of impactor. The other method is to accelerate or decelerate the rotational behavior by modifying velocity profile. Besides, the simulation results of two strategies are compared in magnitude of contact force and impacting frequency.