METHOD FOR SEWING THICK FABRIC IN MOTOR-DRIVEN SEWING MACHINE AND MOTOR-DRIVEN SEWING MACHINE

摘要

PROBLEM TO BE SOLVED: To provide a method for sewing a thick fabric with a motor-driven sewing machine by which the thick fabric can be smoothly sewn even when the machine is operated at a low speed with a low driving torque and the motor-driven sewing machine which can be inexpensively manufactured. SOLUTION: A signal S3 for stopping rotation of a main shaft A is outputted to a hammer operation judging means 24 by a rotational speed detecting means 23 when the number of revolutions detected by a sensor 7 for detecting the number of revolutions is zero for a definite time while the main shaft is rotated or for a definite time from the time when the rotation is started. In response thereto, an indication is given to a PWM outputting means 22 by the hammer operation judging means 24 so as to make on-duty of the above described PWM output to be the maximum duty and to make a control so as to maximize driving torque of a motor 1 for rotating the main shaft.