Determination of Torque-Strain Relationship in an Impact Wrench

Abstract

The impact wrench driver is used to deliver increasing torque with time. In most applications, the torque required needs to be at a predetermined level. The present method of achieving this is based on the skill of operator. The operator ball parks the torque and later measures with a torque wrench, making any necessary adjustments. To achieve a more accurate torque adjustment, it is desired to have a torque read out on the impact wrench. This can also be used to shut off the device when the desired torque is produced. This is achieved by measuring the strain in the stationary planetary gear inside the driving mechanism of the impact wrench. After conducting a series of experiments, the relation between the torque and strain is determined and this relation is used for torque readout. Torsional strain gauge is placed on the gear body. The strain is measured at various torques to formulate relation between the two. To provide a constant torque a friction plate mechanism is used in the experimental setup.