Impact screw-tightening apparatus

U.S. Patent Number: 5715894

Abstract: An impact screw-tightening apparatus is comprised of a main body and a controller. The main body includes a motor outputting pulsed drive output, a main shaft driven by the drive and connected to a screw to be tightened, and a torque detector detecting a change of torque applied to the main shaft. The controller includes a calculating section and a control section. The calculating section obtains frequency of impacts generated from a time that a bearing surface of the screw is in contact with a tightened object, on the basis of the signal from the torque detector. The control section cuts off a motive power source of the drive at a time that the frequency of the impacts becomes a predetermined value. Therefore, even if impact operation is executed prior to the contact of the bearing surface, the tightening force is accurately calculated by a rapid and brief calculation and control logic, and the dispersion of the tightening force at the cut-off time is decreased.

Inventors: Maruyama; Junichi (Yokohama, JP), Nabekura; Tatsumi (Yokosuka, JP)

Assignee: Nissan Motor Co., Ltd. (Yokohama, JP)

Application Number: 08/637,087

Issued: 1998-02-10

Expired: 2006-02-10

Classes: 173/180 ; 173/181; 81/467

Field of search: 173/177,176,180,181,182,183,178 81/467,470 73/761,862.23,862.24

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