Patent ID: 7934428
Filing Date: 2011-05-03
Classification: B25B

Abstract:
1. A system for detecting fastener movement and measuring a residual torque in a fastener joint, comprising: a device for applying torque to a stationary fastener in a tightened state and measuring torque and angle of rotation, the device comprising a sensing system that includes a computing unit in operable communication with the sensing system and adapted to receive the signal corresponding to an angle of rotation of the device and the signal corresponding to the torque applied to the fastener to define a plurality of torque-angle data points, and determine a torque at a time of initial movement of the fastener, wherein determining the time of initial movement of the fastener comprises: determining a base slope for at least one of the plurality of torque-angle data points, wherein the base slope comprises a change in torque over a change in angle for the at least one torque-angle data point and a base point; determining a forward slope for the at least one torque-data point, wherein the forward slope comprises a change in torque over a change in angle for a point subsequent the at least one torque-angle data point and the at least one torque-angle data point; determining a slope delta for the at least one torque-angle data point, wherein the slope delta comprises a rate of change between the forward slope and the base slope; comparing the slope delta of the at least one torque-angle data point to a minimum slope delta.