Pfaff Industriemaschinen Gmbh

G.m. Pfaff Aktiengesellschaft

Oskar Braun

Erich Willenbacher

Reinhold Dobner

Fritz Jehle

Dietmar Becker

Knud Overlach

Ludwig Pietzsch

Sewing machine with swingable stitch forming unit

A sewing machine is provided with a mechanism which is actuated by a drive unit and engages with a needle point insert. The mechanism moves a needle plate insert from a sewing position raised above a needle plate, in which the needle plate reinforces a fabric being clamped to a fabric holder, to a resting position not raised above the needle plate, in which the fabric holder may be moved and the fabric may be changed. The mechanism insures that this movement can be effected in a straightforward manner and with only slight wear and abrasion and while affording accurate transmission. The mechanism is fashioned as a straight-line mechanism with a first oscillating crank which is adjusted for setting the operating height of the needle plate insert and a separator crank for adjusting the insert between a rest position and an operating position.

Sewing machine with a needle plate insert

In a sewing machine with a needle bar executing transverse motions and with a pressing arrangement whose foot can be lowered onto the work piece laterally with regard to its central position when the needle bar executes lateral movements, the presser arrangement and its drive connection to the needle bar is executed so that a minimal moment of inertia is exerted on the needle bar when driving the pressure arrangement and so that the pressure foot always generates a load evenly spread over the pressed surface, independent of the width of its lateral movements. For this purpose the presser foot is movable in transverse direction relative to the other parts of the pressing arrangement and it is guided parallel to the work piece surface by a guiding arrangement. The transverse movement of the presser arrangement is taken from the transverse movement of the needle bar by a driving connection. The driving connection is formed by a driving linkage connected to the needle bar and by a catch connected to the presser foot.

Sewing machine with a presser foot drivable in transverse direction by

A sewing machine with a sensing device positioned ahead of a stitch-forming point, senses changes in the thickness of a material being fed by the sewing machine. In order to determine the difference in thickness, the sensing device has a pickup foot capable of vertical movement with a sensing surface that lies on the material adjacent the point the stitch is formed. A sensing lever is movably mounted on the pick-up foot with a sensing arm that lies on the material ahead of the sensing surface, a measuring member detects the relative movement between the pickup foot and the sensing lever.

Material thickness sensing device for sewing machines

Method and apparatus for determining and regulating the amount of advance of a plurality of workpiece plies at a sewing machine which is affected by scanning the individual plies while recording the stitches being formed between two separate feed points and actuating top and bottom feed devices to achieve a desirable feed of each ply. Signs present or to be applied at any desired point of the workpiece plies are scanned at two successive points, and pulses generated by a pulse generator connected with the main shaft of the machine are summed during this period of time. The pulse sum is compared with a number of pulses which depends on the mutual spacing of the scanning points and on the adjusted stitch length. For two work plies the pulse sums formed between the recognition of the signs are compared directly. As signs to be scanned are used either imprinted marks, the jags of a pinked workpiece edge, or the bright, dark structure of a surface section of the workpiece.

Method and apparatus for determining the amount of advance of a

A workpiece prepuncturing device for use with a sewing machine having drive means for reciprocating a needle and means for feeding a workpiece into association with the needle to sew a stitch comprises a perforating tool which is located at a spaced location from the needle which is comparable to a multiple of the stitch length. The perforating tool cooperates with a counter tool which is mounted on the opposite side of the workpiece and is movable toward and away from the workpiece in timed relationship to the speed of the feed and the reciprocation of the perforating tool. The counter tool is supported in a base portion of the sewing machine by an elastic suspension, and it is in drive connection with the main shaft of the machine which operates the needle and the feed for the workpiece.

Growing community of inventors

Hochspeyer, Germany

Oskar Braun