Pfaff Industriemaschinen Gmbh

Heinrich Bungert

Herbert Wenz

Mathias Ulmen

Klaus Wentz

Dieter Balzer

Process for carrying out a sewing operation with a sewing machine with

A sewing machine with a needle bar mounted in a rocker, has a step motor drive for the oscillation of the rocker. A memory is used in which are contained selected digital data for influencing the step motor and a control unit is inserted between the memory and the step motor for selection and conversion of the digital data into stepping pulses for the step motor. A pulse generator operating synchronously with a main shaft of the sewing machine is used for triggering the transmission of stepping pulses to the step motor. To improve the drive transmission and to avoid reactions on the step motor, the step motor is connected to a lever arm of the rocker via an eccentric transmission.

Sewing machine with step motor operated oscillation drive

A sewing machine includes a housing with a base portion having a covering base plate and an upright standard adjacent one end of the base portion extending above the base plate and an arm portion extending out of the standard and overlying the base plate. A feed drive in the housing includes a ratchet wheel driven by the feed drive located on the arm portion which cooperates with a shuttle carried in the base portion. The feed drive includes a variable drive including an eccentric which may be shifted so as to vary the driving speed of the shuttle. The construction includes a setting device for setting the speed of the shuttle, an actuating device connected to the setting device and the variable drive so that the drive of the shuttle may be varied. The base plate has an opening adjacent the standard with a holding plate pivotally mounted in the opening on an end of a two armed lever which is pivotally mounted in the base and which is effective to permit shifting of the pin actuator to vary the setting of an eccentric drive.

Sewing machine feed setting device

In a sewing machine with a feed device which comprises a feed wheel arranged next to a stitch formation point, driven synchronously with stitch formation tools, and mounted in a support provided at the housing of the sewing machine, in order to obtain an extremely exact drive in both directions, the feed wheel is placed in driving connection with a step motor. In a manner known in itself, the step motor receives stepping pulses which can be generated by a pulse generator operating synchronously with a main shaft of the machine and via a counting device that determines the feed amount. This feed amount is presettable by selectable digital data contained in a memory. In an arrangement wherein the feed wheel is connected to its drive via a deflection gearing and a transmission shaft mounted in the support, the deflection gearing consists of a ring gear attached to the feed wheel and of a pinion firmly connected to the transmission shaft. An especially compact solution results by attachment of the step motor on the support and by rigid coupling of its output shaft to the transmission shaft.

Sewing machine with step motor operated feed device

The machine smoothes stitched seams on shoe shanks and applies a tape to cover the smoothed seam. A driven frictional wheel is cooperable with a second friction wheel rotatably mounted on a relatively elongated support over and along which the shanks are fed, the two friction wheels pressing and smoothing the stitched seams. Two holding elements are releasably engageable with this support at supporting points thereon spaced longitudinally of the support. A control circuit operates in such a manner that the two holding elements initially clamp the support at points spaced longitudinally therealong and, as a shoe shank leaves the friction wheels, the leading holding element is released for passage of the shoe shank therethrough while the trailing holding element remains clamped on the support. As the shoe shank clears the leading holding element, the latter is again clamped on the support and the trailing holding element is released from the support for passage of the shank. As the shank leaves the trailing holding element, the latter is again clamped on the support.

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Kaiserslautern, Germany

Heinrich Bungert