Device for travelling a cloth clamp in an automatic sewing machine

Claim 1

A device for moving a cloth clamp attached to a slide carriage in an automatic sewing machine comprising: a drive cylinder and associated piston, said piston being attached to the slide carriage whereby the slide carriage and cloth clamp are moved reciprocally by respective reciprocal movements of said piston in said cylinder; a pneumatic circuit which supplies a compressible gas to said cylinder to move said piston in a forward stroke; a hydraulic circuit including (a) a first branch which supplies hydraulic fluid to said cylinder to move said piston in a backward stroke, (b) a second branch through which fluid from said cylinder is exhausted during the forward movement of said piston, said second branch including a control valve and a throttle valve disposed in series whereby the forward stroke of the piston is slowed by said throttle valve to an intermediate speed and halted by closure of said control valve, and (c) a third branch through which fluid from said cylinder is exhausted during the forward movement of said piston, said third branch also providing a shunt route for said second branch, and including a control valve whereby fluid from said cylinder is exhausted rapidly when said control valve is opened to effect a rapid forward stroke of said piston; and a throttle actuating means for actuating said throttle valve of said second branch to effect a further slowing of the forward stroke of said piston, whereby the forward movement of the cloth clamp is reduced to a slow speed; whereby a forward movement of the cloth clamp is effected by said second branch such that a halt stich is performed when the cloth clamp is stopped, a condensed stich is performed when said throttle actuating means actuates said throttle valve and the cloth clamp is moved with the forward stroke of said piston at the slow speed, and a normal stich is performed when the cloth clamp is moved with the forward stroke of said piston at the intermediate speed, and whereby a rapid forward movement of the cloth clamp is effected by said third branch when no stiching is occuring.

Claim 2

A device for moving a cloth clamp attached to a slide carriage in an automatic sewing machine comprising: a drive cylinder and associated piston, said piston being attached to the slide carriage whereby the slide carriage and cloth clamp are moved reciprocally by respective reciprocal movements of said piston in said cylinder; a pneumatic circuit which supplies a compressible gas to said cylinder to move said piston in a forward stroke; a hydraulic circuit including (a) a first branch which supplies hydraulic fluid to said cylinder to move said piston in a backward stroke, (b) a second branch through which fluid from said cylinder is exhausted during the forward movement of said piston, said second branch including a control valve and a throttle valve disposed in series whereby the forward stroke of the piston is slowed by said throttle valve to an intermediate speed and halted by closure of said control valve, and (c) a third branch through which fluid from said cylinder is exhausted during the forward movement of said piston, said third branch also providing a shunt route for said second branch, and including a control valve whereby fluid from said cylinder is exhausted rapidly when said control valve is opened to effect a rapid forward stroke of said piston; and a throttle actuating means for actuating said throttle valve of said second branch to effect a further slowing of the forward stroke of said piston, whereby the forward movement of the cloth clamp is reduced to a slow speed; whereby a forward movement of the cloth clamp is effected by said second branch such that a halt stich is performed when the cloth clamp is stopped, a condensed stich is performed when said throttle actuating means actuates said throttle valve and the cloth clamp is moved with the forward stroke of said piston at the slow speed, and a normal stich is performed when the cloth clamp is moved with the forward stroke of said piston at the intermediate speed, and whereby a rapid forward movement of the cloth clamp is effected by said third branch when no stiching is occuring.