Sewing machine control - uses motor speed and needle position to regulate motor speed according to the situation and prevent slip

摘要

The sewing machine control system establishes the rotary speed of the electro-motor and the needle position. The rotary transfer ratio is calculated from the needle position recognition signal and the output of the rotary speed meter. The start time of the computation is controlled, and the speed of the electro-motor is regulated according to the computed results. Pref. the computing start time is controlled to come into effect after a given time from the start of the electro-motor. The increase rate, by time, during an acceleration speed command to set the rotary transfer ratio and while measuring the rotary transfer ratio is less than after the end of the operation to determine the rotary transfer ratio, and this value is reduced to a given speed:time ratio. On the development of a fault, while establishing the rotary transfer ratio, the rotary ratio is less than before the fault developed and the motor speed is regulated by multiplying the sewing machinee speed with the rotary transfer ratio. After the situation has been assessed, a data value is applied to the computer outside the preset value range which is applicable to the measurement time period or a computing result to give a much lower motor speed. ADVANTAGE - The system stops the operation in the even of a breakage or other stoppage, prevents slip, and reduces working speeds for safety when a fault develops.