Pfaff Industriemaschinen Gmbh

G.m. Pfaff Aktiengesellschaft

Fritz Jehle

Erich Willenbacher

Dietmar Becker

Karl-Heinz Walther

Oskar Braun

Heribert Geisselmann

Edgar Butzen

Manfred Frank

Gunther Denuell

Rubi Schonthaler

Shortening of needle thread end at the beginning and end of sewing in

Process and sewing machine for sewing together layers of fabric

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 sewing machine for automatically making edge-parallel seams comprises a scanning device for recognizing the geometric form of the workpiece edge and a pressure piston lowerable laterally of the stitch formation point. For straight workpiece edges extending at an angle to each other, the pressure piston, having been lowered onto the workpiece with the sewing machine stopped, is rotated around the needle which is inserted in the workpiece, the workpiece being taken along accordingly. For a convexly arcuate edge pattern, first the lateral distance of the pressure piston from the needle is readjusted in such a way that it corresponds to the radius of the edge arc (e.g. scallop). Thereafter, with the sewing machine continuing to run, the pressure piston is lowered, whereupon the feed dog of the sewing machine rotates the workpiece around the pressure piston.

Sewing machine for automatically making edge-parallel seams

A sewing machine with guide mechanism for automatically producing a curved edge parallel seam comprises a scanning unit for scanning the edge of a workpiece and sensing when the edge of the workpiece moves away from an edge guide which indicates the presence of a curved edge, a workpiece feeder for feeding the workpiece along the guide edge, a workpiece pressure stamp for applying pressure on the workpiece at a point spaced from the guide to cause rotation of the workpiece about the point when the pressure stamp is activated and a circuit connected between the scanning unit and the pressure stamp for intermittently activating the pressure stamp when the scanner senses the presence of a curved edge area of the workpiece.

Sewing machine for producing curved edge parallel seams

A device for the automatic guiding of a workpiece on a sewing machine to produce a curved edge parallel seam operates in conjunction with a sewing machine having a reciprocating needle and a presser foot engageable with the workpiece and a feed member engageable with the workpiece to move it relative to the needle. The sewing machine also includes a guide roll disposed in spaced relationship to the needle for guiding the edge of the workpiece and a scanner for scanning the workpiece edge for sensing its position. In accordance with the position sensed, a plunger is mounted above the workpiece and is movable into the engagement with the workpiece to hold the workpiece at a selected point so as to turn the workpiece during the feeding movement of the workpiece by this feed member. A fluid pressure operated drive is connected to the plunger so as to engage it with the workpiece and the operation thereof is dependent upon a second fluid pressure drive which varies the operation of a stitch length setting mechanism which includes a stitch length setting bar which is movable to change the length of the feeding movement of the feed member.

Device for the automatic guiding of a workpiece on a sewing machine

The device is for use in a sewing unit including a sewing machine and includes a vertically oriented relatively elongated intermediate plate separating two plies of material in advance of the sewing machine. Guide elements adjacent the intermediate plate support a clasping station for movement longitudinally of the intermediate plate. The clasping station includes a support mounting two clasps each selectively engageable with a respective ply of material. Photoelectric sensing devices are movable with the clasping station, and include respective sensing devices operatively associated with each ply of material and each operable to control engagement of a respective clasp with the associated ply of material responsive to sensing of the trailing edge of the associated ply of material. A counterweight arrangement exerts an adjustable pull on the clasping station in a direction opposite to the feed direction of the plies of material. In one embodiment, a lifting carriage supports the sensing devices and effects lifting of the clasping station. In a second embodiment, the sensing devices are mounted on the same support which mounts the clasps.

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Enkenbach-Alsenborn, Germany

Fritz Jehle