Durkoppwerke Gmbh

Horst Plassmeier

Heinz Goldbeck

Klaus Moller

Herbert Struck

By means of this method and apparatus for sewing a seam, it is possible to end a seam exactly at a predetermined location. When the predetermined location is reached, the forward movement of the sewing material is interrupted, and only the stitch that had been begun at the time of the interruption is completed. In this way, on the one hand, visually attractive seams can be produced and, on the other hand, it is possible to sew a small part onto a main part with a seam which does not extend past the small part.

Method and apparatus for sewing a seam ending at a predetermined location

A sewing device for producing piped openings such as pocket slashes, with or without a pocket flap. The sewing device includes a two-needle sewing machine having a vertically moveable center knife for cutting an opening to be piped, a cutting device including two vertically moveable angle cutting knives for performing gusset cuts, and a material transport device for receiving material to be sewn and transporting such material between the sewing machine and the cutting device. Also provided is a control system including a microprocessor for adjusting the operating positions of the various components to move the points of commencement of the parallel seams, the center knife, and the angle cutting knives, individually or jointly, forward or backward, to conveniently and selectively change these sewing parameters in response to the specific workpiece. In one embodiment, a common drive motor is provided for the two-needle sewing machine, the transport device, and the cutting device. Alternatively, the mechanism is substantially simplified in a sewing device wherein the two-needle sewing machine is driven by a first electric motor, and the transport device and the cutting device are driven by at least one additional electric motor.

Sewing device for producing piped openings in sewing material

A pocket opening sewing machine including a cutting device for producing two notching cuts at the ends of a pocket opening. The sewing machine has sewing needles and a belt driven clamping device for clamping to the sewn parts for advancing them in an advancing direction. The cutting device includes two knives spaced apart. The knife that is further from the sewing needles is movable toward the stationary knife that is closer to the needles. For adjusting the spacing between the knives, the movable knife is temporarily clamped to a moving belt which moves it toward the stationary knife. An adjustably positionable stop defines the furthest limit of spacing between the stationary and movable knives and a spring drives the movable knife against the stop. The clamping of the movable knife to the belt is initiated by a sensor which senses the passage of a sewn part and which operates a microcomputer with pocket length information stored in it to move the movable knife when required over the distance required. Alternately, if the movable knife moves at a speed faster than the advancing speed of the sewn parts, adjustment of the movable knife stop can be dispensed with.

Automatic pocket opening sewing machine having a cutting device for

A fully digital control system for the speed of the arm shaft of a sewing machine provides separate counters for counting a counting frequency during the pulses and pulse intervals of a lower frequency increment generator measuring the actual value of the shaft speed. The inverse of the last complete count thus registered is compared with a set point value in a microcomputer preprogrammed with data blocks representing these set point values and provided with parameters for the respective keying ratios associated therewith. The control bus and data bus connecting the counters with the microcomputer also connect the latter to another unit including a bit-rate generator and a programmable retriggerable multivibrator from which the digital output signal is emitted to effect direct control over a DC motor or to drive a clutch connected to the shaft.

Digital control system for the speed of a sewing machine

To test the integrity of a plurality of operating circuits each including a load energizable by an associated driver under the control of a microcomputer, a capacitor charged with unipolar pulsating test voltage is connected to a common terminal of all the operating circuits and concurrently therewith to the input of a trigger element whose threshold equals about half the peak amplitude of that voltage. During one or more brief intervals the microcomputer cuts in the driver of a selected circuit and senses the output voltage of the trigger element to determine whether or not the capacitor is being discharged through that circuit. A display device controlled by the microcomputer indicates the conductive or blocked state of the selected circuit as well as a possible malfunction manifesting itself in a discharge of the capacitor before any driver is turned on.

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Herford, Germany

Horst Plassmeier