Title:
SCREW DRIVER
Document Type and Number:
Japanese Patent JPH01127281
Kind Code:
A
Abstract:
PURPOSE: To substantially improve torque accuracy by controlling a power applied to a driver unit and a drive pulse applied to a power transistor in PWS control. CONSTITUTION: A current passing through a driver motor 15 is read by a current detector 14, a current detection conversion circuit 8, and an A/D converter 5. The resistance of the motor 15 is detected by a detection circuit 7 and is read as a speed factor by a converter 5. A chopper type power source 4 and a power transistor 13 are controlled in PWM by a CPU 1. When a change caused by the seating of a screw on a work is detected in detection values of the detection circuit 7 and the current detector 14, the CPU 1 gives a braking command to apply a reverse braking force to the motor 15 and limits a current for a predetermined period. Then, the rotation of the motor 15 is gradually increased to fasten the screw at setting torque without rotational inertia.
Inventors:
OKUBO MASAYUKI
NISHIDA YOSHIKAZU
NAKAJIMA KOSHIROU
NISHIDA YOSHIKAZU
NAKAJIMA KOSHIROU
Application Number:
JP28357087A
Publication Date:
May 19, 1989
Filing Date:
November 10, 1987
Export Citation:
Assignee:
MATSUSHITA ELECTRIC IND CO LTD
International Classes:
B25B23/151; B25B23/14; (IPC1-7): B25B23/151
Domestic Patent References:
| JPS5988265A | 1984-05-22 |
Attorney, Agent or Firm:
Tomoyuki Takimoto (1 person outside)