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. 27, 1996
Filed:
Nov. 29, 1994
Masafumi Matsumura, Kariya, JP;
Junichiro Kanamori, Nisshin, JP;
Nippondenso Co., Ltd., Kariya, JP;
Abstract
A screw tightening apparatus including an electric screwdriver having a bit shaft adapted to hold a male screw to be threaded to a female hole in a workpiece and a drive mechanism arranged to move the screwdriver toward and away from the mounting hole of the workpiece is disclosed. The screwdriver and drive mechanism are controlled in such a manner that the bit shaft is driven at a low speed and applied with a small thrust force at an initial stage during which the male screw is located to be engaged with the mounting hole. Then the bit shaft is driven at a higher speed than that at the initial stage and applied with a larger thrust force than that at the initial stage during an interim stage when the male screw is threaded into the mounting hole. Finally, the speed of the bit shaft is reduced so that the bit shaft is driven at a lower speed than that at the initial stage and applied with a larger thrust force than that at the interim stage at a final stage during which the male screw is tightened and seated on the workpiece.