Method of tightening threaded fasteners
Patent 4685050 Issued on August 4, 1987. Estimated Expiration Date: 
June 11, 2005. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
June 11, 2005. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesMethod and apparatus for fastener tensioning Tension control of fasteners Apparatus and method for tightening an assembly Dynamic friction indicator and tightening system usable therewith Method of measuring previously applied torque to a fastener Patent #: 4426887 InventorsAssigneeApplicationNo. 06/743562 filed on 06/11/1985US Classes:700/32, Specific criteria of system performance173/183, Proximity angle detector702/42, Stress or strain measurement73/761, Threaded fastener stress81/467Responsive to torque on workExaminersPrimary: Ruggiero, JosephAttorney, Agent or FirmInternational ClassB25B 23/14 (20060101)Foreign Application Priority Data1984-06-16 DEAbstractThe invention is directed to a method for tightening threaded fasteners by means of a controlled fastener-driving tool. The tightening of the fasteners is controlled by the elastic limit thereof. The slope of the actual load-strain characteristic curve is continuously determined during the fastener-driving operation. This actual slope is compared with a predetermined slope determined with reference to a characteristic curve. When the predetermined slope is reached, a control signal is generated to switch off the fastener-driving tool. In practice, departures occur in the actual characteristic curve of an actual fastener-driving operation. In order to compensate for such departures from the characteristic reference characteristic curve, a comparison is made in the straight portion of the actual load-strain characteristic curve with the predetermined characteristic slope of the reference characteristic curve and a corrective value for transformation of one characteristic curve to the other is formed in the presence of a departure of the slopes. For this purpose, before the actual determined slope is compared with the predetermined switch-off slope one of the two quantities is transformed by means of a corrective value. | |
