Industrial sewing machine pneumatic controls - incl sensor for stopping air supply when work piece absent

摘要

An industrial sewing machine operating in a cyclic phase and having a pneumatic control and an aspirator nozzle for gathering the stitching yarn at the beginning and end of each face has a sensor (pref. photoelectric) which detects the presence or absence of a work-piece on the sewing machine table and operates e.g. an electromagnetic valve to supply compressed air from a source to one or other of the inlets of an 'or' gate. A suction is set up in pref. a side duct connecting with the main feed line from the source and the 'or' gate operates a pilot valve to connect the side duct to the aspirator nozzle. Pref. the machine has a foot pedal which when lightly depressed allows compressed air to be supplied to a first ram which controls the drive motor of the machine to rotate at low speed and when fully depressed allows supply of the air to a second ram which controls the motor to operate at first speed. Thus cost of operation of the machine is reduced.