Simplified fastening technique using the logarithmic rate method
First Claim
1. Apparatus for tightening a threaded fastener, comprisinga powered tool for imparting input characteristics to the fastener;
- means for sensing the input characteristics and generating signals representative thereof;
means responsive to the generated signals and to a ratio of a final desired tension value in the fastener and a tension rate of the fastener for determining a final shut off parameter; and
means for terminating operation of the tool in response to the final shut off parameter.
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Abstract
A fastening tool, which is preferably portable, incorporates torque and angle sensors connected to an analog calculating circuit which determines, while tightening below the yield point of any component of the joint being tightened, a final shut off parameter which varies from joint to joint while tightening seriatim a plurality of substantially identical joints. The logarithimic rate method is used to determine the final shut off parameter. In accordance with one embodiment of the invention, a simplification occurs by the measurement of an angle interval occurring between two predetermined torque values. In accordance with another embodiment of the invention, a simplification occurs by measuring the torque value existing at a predetermined angle interval beyond a first predetermined torque level.
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Citations
20 Claims
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1. Apparatus for tightening a threaded fastener, comprising
a powered tool for imparting input characteristics to the fastener; -
means for sensing the input characteristics and generating signals representative thereof; means responsive to the generated signals and to a ratio of a final desired tension value in the fastener and a tension rate of the fastener for determining a final shut off parameter; and means for terminating operation of the tool in response to the final shut off parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. Apparatus for tightening a joint including a threaded fastener, comprising
a powered tool for imparting torque and rotation to the fastener including means for sensing a function of torque imparted to the fastener and generating a signal representative thereof and means for sensing a function of rotation of the fastener and generating a signal representative thereof; -
a control circuit for determining, while tightening below the yield point of any joint component that can be correlated with stress in the fastener, a final shut off parameter variable from joint to joint in response to three parameters sensed by the sensing means, including means for predetermining, before tightening, two of the three parameters; and means for determining, during tightening, the third parameter; and means for terminating operation of the tool in response to the final shut off parameter. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification