Pfaff Industriemaschinen Gmbh

Herbert Wenz

Heinrich Bungert

Franz Schneider

Dietmar Becker

Mathias Ulmen

Klaus Wentz

Gunter Link

A sewing machine which is used with manual feed movement of a sewing material has a holding device for the material that is effective during the first phases of stitching of a seam section, by which the first thread knot is held from becoming undone when short thread ends and a large feed movement are used. In a first embodiment, the holding device includes a holding foot, by a drive mechanism in addition to a presser foot which is periodically moved up and down by a drive mechanism, and a controllable drive for the holding foot. In a second embodiment, the holding device includes a presser foot, a compression spring and a decoupling mechanism by which the presser foot can be disconnected from its drive mechanism.

Sewing machine with workpiece holder for securing initial seam stitches

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

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

A method for approaching a predeterminable end point of a seam spaced from the edge of a workpiece, with a sewing machine which comprises an adjustable needle and lower transport, a sensor arranged before the needle and triggering the process for the positioning of the needle in the end point during passage through the edge, a pulse generator coupled with the main shaft of the sewing machine for the delivery of counting pulses for a pulse counter, and a micro-computer which controls the action of the feed means as a function of the pulses originating from the sensor and from the pulse generator. To execute a desired shortening of the length of one or more of the last stitches before the end point of a seam, the workpiece is moved back by the difference between the desired stitch length and the stitch length set by the setting device, before execution of the adjusted feed. For correction of the stitch length executed during the feed phase, the cloth feeder is connected with a switching gear controlled by the micro-computer for controlled switching on during its reversed feed phase which precedes the respective forward feed phase.

Method and sewing machine for approaching a predetermined end point of a

A lubricating system for sewing machines is produced with the sewing machine running by cutting a predetermined amount of cotton fibers into small lengths and blowing the fiber lengths into the sewing machine housing. As the fibers fill the housing a felt cushion conformable to the paths of motion of the parts of the mechanism is produced. The felt cushion is supplied with oil through a wick.

Lubricating system for sewing machines

A cover construction for a sewing machine work support column which is adapted to contain a looper and a thread-cutting device comprises an upright support member or column upon which a substantially L-shaped cover member is pivotal. The cover member includes a cover plate portion which extends horizontally in a closed position and covers the top of the device and a side portion which extends vertically in a closed position. The cover plate member is openable to a position opened outwardly from the support member in which position the cover is located in a vertical position and the side portion in a horizontal position. The side portion includes two bearing faces which are defined on the back and the bottom faces thereof, respectively, and which will abut against a top bearing surface of a locking member which is displaceable along the height of the upright support member. In the open position, one bearing face on the side wall is engaged on the locking member and in the closed position, the bottom bearing face engages on the top of the locking member. The locking member is biased by a coil spring around the mounting member in an upward direction in which it contracts the bearing face on the side wall in an open position of the cover and the bearing face on the bottom wall in the closed position of the cover. In addition, the cover has a torsion spring associated with it which rotates it to an open position when the locking member is pushed downwardly against its biasing spring.

Cover construction for a sewing machine work support column

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

Herbert Wenz