Pfaff Industriemaschinen Gmbh

Richard Muller

Walter Hager

Axel Zinssmeister

Roland Leis

A sewing arrangement is provided with a feed device which comprises a drive device, a pitman drive, and a work holder received by a support. The feed device, designed so as to be subject to little wear, permits the execution of purely translatory movements with great accuracy, in that the pitman drive has associated with it a parallel guiding means which together with the pitman drive is articulated to the support of the work holder.

Sewing arrangement with feed device

An air cylinder has a main piston which is movable backwardly and forwardly under the control of air pressure and it is closed on at least one end with an axially extending damping bore which terminates in a closed end having a stop member adjacent this end. A vent hole connects to the interior of the cylinder to the damping bore and another vent hole connects into the cylinder main space. Each vent hole is advantageously connected to a throttle and check valve which permits inflow of air to the associated spaces and a throttled exit of the air depending on the position of the piston in the cylinder. The piston carries a damping piston in the form of a cylindrical extension thereof which is movable with the piston toward the closed end and has an open end with an axially extending damping bore therein having a check valve which closes the opening. The damping piston moves with the main piston so that adjacent the end position of movement of the main piston, the damping piston enters into the damping bore so as to bring its end into proximity to the stop which opens the check valve. The effect is to cause a slowing motion of the main piston until the stop reaches the check at which the main piston approaches substantially its end position at which time the remainder of the air trapped ahead of the main piston is exhausted through one or more of the vent holes.

Air cylinder with end position damping

The invention relates to a feed drive for work holders of sewing assemblies, by which, during the formation of the initial stitches of a seam taking place at a low speed, the control cam plate moving the work holder is driven at a reduced speed, and, during the formation of the main part of the seam taking place at a high sewing speed, the control cam plate is driven intermittently in a manner such that at every lowermost position of the needle, the work holder is temporarily stopped. The feed drive comprises a planetary gearing having two inputs, of which the first input can receive a constant rotary motion, and the second input can receive, at the start of the seam formation, a continuous rotary motion which is subtractively superimposed upon the rotary motion at the first input, and, during the ordinary sewing operation, an oscillatory motion whose frequency is equal to the frequency of the needle bar motion.

Growing community of inventors

Mehlbach, Germany

Richard Muller