Digital retorque measuring apparatus
First Claim
1. In a method of detecting breakaway or valley torque levels associated with the amount of previously applied torque to a fastener wherein torque is subsequently applied to the fastener in the tightening direction until further motion of the fastener is obtained, and wherein an analog signal is generated as a function of the subsequently applied torque, the improvement comprising:
- (a) defining a window of digital sample values in a memory by using a microprocessor to sample the analog signal and generate digital sample values therefrom until an analysis of said samples indicate that samples corresponding to the breakaway and/or valley torque levels have been stored in memory; and
(b) thereafter, using said microprocessor to examine the characteristics of the samples within the window to search for those samples corresponding to the breakaway and/or valley torque levels.
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Accused Products
Abstract
A microcomputer based system is designed to accurately detect the amount of previously applied torque to a fastener by way of a retorque test in which torque is subsequently applied to the fastener in the tightening direction until breakaway occurs. As torque is subsequently applied to the fastener a microprocessor operates to sample an analog torque input signal and convert it into discrete digital samples. These digital samples are stored in sequential memory locations during the tightening process. The microprocessor stops generating any further samples once a window containing the values of interest has been defined in memory. Then, the microprocessor examines the stored window samples in more detail to detect the sample value associated with the amount of torque previously applied to the fastener.
39 Citations
10 Claims
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1. In a method of detecting breakaway or valley torque levels associated with the amount of previously applied torque to a fastener wherein torque is subsequently applied to the fastener in the tightening direction until further motion of the fastener is obtained, and wherein an analog signal is generated as a function of the subsequently applied torque, the improvement comprising:
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(a) defining a window of digital sample values in a memory by using a microprocessor to sample the analog signal and generate digital sample values therefrom until an analysis of said samples indicate that samples corresponding to the breakaway and/or valley torque levels have been stored in memory; and (b) thereafter, using said microprocessor to examine the characteristics of the samples within the window to search for those samples corresponding to the breakaway and/or valley torque levels. - View Dependent Claims (2, 3, 4)
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5. A method of detecting the amount of previously applied torque to a fastener, said method comprising:
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subsequently applying torque to the fastener in the tightening direction until further motion is obtained; generating an analog signal as a function of the subsequently applied torque; using a microcomputer to convert said analog signal into a plurality of digital samples; loading said samples in a memory while checking for substantial deviations between the slopes of successive sample segments; terminating the conversion and loading operations when the slopes of successive sample segments deviate from a given value thereby defining a window of digital samples in said memory; and examining the digital samples in said window for a value which is closely associated with the amount of previously applied torque to the fastener.
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6. In a system for measuring the amount of previously applied torque to a fastener, the improvement comprising:
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input means for receiving an analog torque signal representative of the amount of torque subsequently applied to the fastener until motion is obtained; converter means for converting said analog torque signal into a plurality of digital samples; memory means for storing a given number of said samples; means for loading said samples into sequential memory locations until the slopes of successive sample segments deviate substantially from a given value thereby defining a window of digital samples in said memory; and means for examining said digital samples stored in the window for a value associated with the amount of torque previously applied to the fastener. - View Dependent Claims (7, 8)
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9. A method of determining the breakaway torque level associated with the amount of previously applied torque to a fastener, said method comprising:
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generating a curve of torque values representing the amount of torque subsequently applied to the fastener until motion is obtained; detecting a first line segment on the curve having a slope which first begins to substantially deviate from the maximum slope of the curve; detecting a second line segment on the curve having the least positive slope; and displaying as said breakaway torque level the value on the curve associated with the intersection of projections from the first and second line segments.
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10. In an apparatus for detecting breakaway or valley torque levels associated with the amount of previously applied torque to a fastener wherein torque is subsequently applied to the fastener in the tightening direction until further motion of the fastener is obtained, and wherein an analog signal is generated as a function of the subsequently applied torque, wherein the improvement comprises:
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means for sampling the analog signal and generating digital sample values; means for storing said samples in a digital memory until an analysis of said samples indicates that samples corresponding to the breakaway and/or valley torque levels have been generated and stored in memory; and means for examining the characteristics of the samples in the memory to search for samples corresponding to the breakaway and/or valley torque levels.
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Specification