The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 04, 1987
Filed:
Jun. 11, 1985
Bernhard Polzer, Riesburg, DE;
Johann Roemischer, Lauchheim, DE;
Deutsche Gardner-Denver GmbH, Westhausen, DE;
Abstract
The 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.