Abstract: A system for monitoring and/or controlling the torque applied by a fluid driven tool for driving threaded fasteners, such as tools driven by either air or oil. The system includes a fluid flow meter to measure a parameter which is a function of the rate of fluid flow into the tool during operation of the tool, a transducer for converting the measured parameter into an electrical signal, and a data processing unit for processing that electrical signal into a signal representative of the torque applied by said tool. A system for digitally processing the measured parameter and comparing it to predetermined expected parameters to infer the condition of the fluid driven tool and for reporting that inferred condition is also included. The system is applicable to both nutrunner type fluid tools and impact wrenches.

Abstract: A system for monitoring and/or controlling the torque applied by a fluid driven tool for driving threaded fasteners, such as tools driven by either air or oil. The system includes a fluid flow meter to measure a parameter which is a function of the rate of fluid flow into the tool during operation of the tool, a transducer for converting the measured parameter into an electrical signal, and a data processing unit for processing that electrical signal into a signal representative of the torque applied by said tool. A system for digitally processing the measured parameter and comparing it to predetermined expected parameters to infer the condition of the fluid driven tool and for reporting that inferred condition is also included. The system is applicable to both nutrunner type fluid tools and impact wrenches.

Abstract: A method of utilizing a non-contact velocity sensor is disclosed which involves a subpoint set delay and reset feature as a means for minimizing problems with zero drift that would cause inaccuracies in tightening procedures.

Abstract: A self-contained impact wrench having an adaptive control system for determining the yield point or some similarly significant tightened condition of a fastener assembly by detecting a signal representative of the forward rotation angle of the fastener assembly is disclosed. One embodiment utilizes a computed signal of time over a fixed interval of forward rotation angle, as an estimate of the torque applied by the impact wrench, and the torque estimate vs. rotation angle curve is differentiated to obtain the gradient thereof. Successive gradient values are stored and compared, and when the present gradient value has attained a predetermined relationship relative to a stored value of a gradient in a tightening region of the curve, further tightening of the fastener assembly is discontinued. This ensures that the yield point or other similarly significant tightened condition of the assembly has been reached.

Abstract: The preferred embodiment of the invention disclosed in this application includes a wrench, for example an operator powered wrench, for tightening a fastener assembly by the incremental application of tightening force. Also included is a control circuit for detecting a phenomena indicating that the joint assembly in which the fastener assembly is installed has been tightened to its yield point. The control circuit further includes checking means for determining that the fastener assembly is being tightened to assure that when the phenomena is detected, the joint assembly has been tightened to the yield point.

Abstract: The invention disclosed herein relates to a tightening system for tightening an assembly including a threaded fastener including a wrench for applying torque and imparting rotation to the fastener. Associated with the wrench is a control system including measuring means for developing a first signal representative of the angular displacement of the fastener. A second signal representative of a constant incremental time is introduced along with the first signal to gradient calculating means which develops a signal representative of the slope or gradient of an angular speed vs. angular displacement curve which could be plotted for the particular assembly being tightened. When the gradient signal falls to a predetermined percentage of a maximum previously stored gradient signal, at the yield point of the assembly or some similarly significant point characterized by a significant change in slope on the angular speed vs.