Abstract: A load-indicating device including a load-bearing member adapted to deform when stressed. Ultrasonic waves are directed into one end of the load-bearing member and ultrasonic echoes are received at the same end by ultrasonic wave transmitting and receiving equipment. In one embodiment, ultrasonic waves are transmitted and received using an ultrasonic transducer disposed on either the head or the opposite end of the load-bearing member. The head, the end, the shank or a combination thereof are contoured to reduce the influence of geometric variations and asymmetrical stress in the load-bearing member on the ultrasonic measurement. A method is also provided, which encompasses a model, by which preferred geometries of the contoured surfaces of the load-bearing member can be designed.

Abstract: A method of measuring in a material a time-of flight of a signal having a first signal burst and a second signal burst, the first signal burst having a first set of cycles and the second signal burst having a second set of cycles. The method includes identifying a cycle in the second signal burst corresponding to a cycle in the first signal burst, to measure the time-of-flight of the signal.

Abstract: A load indicating device and a method of using a load indicating device for monitoring the deformation in and imparting torque to a load bearing member are disclosed and claimed. An ultrasonic transducer, grown on one surface of a load bearing member, such as a fastener, is used to determine the length, stress or other tensile load dependent characteristic of the member using ultrasonic techniques.

Abstract: An ultrasonic signal drive/sense circuitry is provided, which circuitry is adaptable to a variety of automated or manual fastener tightening operations. This circuitry operates for measuring tension in a fastener as a function of change in time of flight of an ultrasonic wave. A microcontroller directs the operation of circuit components to generate high amplitude, high repetition rate, drive pulses with these amplitude and repetition rate factors being electronically adjustable to compensate for fastening tool and fastener acoustical properties and tightening rates. Software driven timing circuitry calculates, calibrates and adjusts pulse echo detection window width and center location and also optimum echo detection threshold. This timing circuitry is implemented by digital techniques to measure pulse time of flight and incorporates analog interpolation of data between digital counts. Sampling rates of the echo pulses are adjusted to tool speed.

Abstract: A load indicating cell and a method of manufacturing a load indicating cell are disclosed and claimed. An ultrasonic transducer, grown on one surface of a load bearing member, such as a fastener, is used to determine the length, stress or other tensile load dependent characteristic of the member using ultrasonic techniques.

Abstract: A load indicating member and load indicating fastener are disclosed and claimed. An ultrasonic transducer, grown on one surface of a load indicating member, such as a fastener, is used to determined the length, stress or other tensile load dependent characteristic of the member using ultrasonic techniques.

Abstract: An electrical contact structure for making and maintaining an electrical connection through a rotatable tool head is provided. A low cost contact probe assembly can be incorporated into the drive of various conventional tightening tools to extend onto the head of a fastener to make and maintain electrical contact therewith while the head is being operated upon by the socket or gripping means of the tightening tool. This contact probe assembly includes an insulated and shielded electrically conductive tube.

Abstract: This invention relates to a load indicating member comprising a shank having at least one groove and an ultrasonic transducer coupled to a load indicating member so that an ultrasonic wave is directed to the groove. A surface can be formed adjacent to one longitudinal end of the shank and the ultrasonic transducer can be coupled to this surface. Further, the ultrasonic transducer can be coupled to this surface so that the ultrasonic wave is also directed to the other longitudinal end of the shank which is remote from the surface. The groove may be located on the shank at a predetermined distance from the surface for identification of the member. Moreover, the surface can have a recess, with the ultrasonic transducer being located in the recess. Advantageously, the groove can be an annular groove or the groove can be comprised of threads disposed on the shank. Also, the shank can have two or more annular grooves.

Abstract: An electrical contact structure for making and maintaining an electrical connection through a rotatable tool head is provided. A low cost contact probe assembly can be incorporated into the drive of various conventional tightening tools to extend onto the head of a fastener to make and maintain electrical contact therewith while the head is being operated upon by the socket or gripping means of the tightening tool. This contact probe assembly includes an insulated and shielded electrically conductive tube.

Abstract: A method of measuring the load in a member subjected to longitudinal stress, a load measuring device and a fastener tightening device using the method of measuring, a load indicating member and a load indicating fastener for use in conjunction with the method of measuring, a method of making the load indicating fastener, a method of tightening the load indicating fastener and a transducer for instrumenting a load bearing member are each disclosed and claimed. A thin piezoelectric sensor consisting of a piezoelectric film sandwiched between two thin electrodes is permanently mechanically and acoustically coupled to the upper surface of a member and is used to determine the length, tensile load, stress, or other tensile load dependent characteristic of the member by ultrasonic techniques.

Abstract: A method of measuring the load in a member subjected to longitudinal stress, a load measuring device and a fastener tightening device using the method of measuring, a load indicating member and a load indicating fastener for use in conjunction with the method of measuring, a method of making the load indicating fastener, a method of making the load indicating fastener, a method of tightening the load indicating fastener and a transducer for instrumenting a load bearing member are each disclosed and claimed. A thin piezoelectric sensor consisting of a piezoelectric film sandwiched between two thin electrodes is permanently mechanically and acoustically coupled to the upper surface of a member and is used to determine the length, tensile load, stress, or other tensile load dependant characteristic of the member by ultrasonic techniques.

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.