Durkoppwerke Gmbh

Durkopp Adler Aktiengesellschaft

Durkoppewerke Gmbh

Gunter Droste

Wilhelm Stapel

Klaus-Dieter Seiler

Klaus D Seiler

Rolf Ellermann

Hermann Niehaus

Wilheim Stapel

A thread-pulling device is fastened on the arm of a sewing machine. The thread-pulling device has a thread clamp that can be opened and closed on the thread, and can be moved toward and away from the sewing machine arm. In operation, the needle thread, which has been pulled off the spool and extends to the sewing needle, is conducted through the thread clamp. After an initial seam has been completed, the thread clamp is closed on the thread and moved to an extended position which is remote from the arm. In this way, a given length of the needle thread is pulled off the spool, thus providing the proper length of needle thread for dependable formation of the first stitch of the following seam. Then, shortly after the start of the following sewing process, the thread clamp is moved back over an intermediate distance toward the sewing machine arm so as to pull back the initial piece of the needle thread that is now hanging down from the back of the material at the start of the seam. The initial piece of needle thread is pulled back to such an extent that only a short piece of the needle thread, of predetermined length, will remain on the back of the material.

Thread manipulations at the beginning and end of a seam

A servo device for a multineedle sewing machine which includes two needle bars; driving and steop devices for said needle bars; devices for engaging and disengaging the two needle bars relative to the driving and stop devices; a feed-length adjustment device associated with at least one feed dog for the transport of the material being sewn; an adjustable thread tensioning device for the needle threads; devices for locking each needle bar selectively in its highest position; a positioning drive for the multineedle sewing machine; and a device including a position indicator attached to an arm shaft of the multineedle sewing machine, for adjusting the speed of rotation and positioning of the needle bars in predetermined positions. The servo device comprises a control system including a pair of electrical switches which respectively correspond to the needle bars, for controlling the engagement and disengagement of the needle bars relative to the driving and stop devices; a first setting device associated with the control system, for selectively interrupting the transport by the feed dog of the material being sewn; and a second setting device associated with the control system, for temporarily increasing a thread tensioning force exerted on the needle thread by the thread tensioning device.

Servo device for a multineedle sewing machine with engageable and

A double-lock-stitch sewing machine has a reciprocating needle forming an upper-thread loop with the aid of a rotary gripper assembly. The loop is carried by and formed by a main hook or point of the assembly around a stationary bobbin to engage a bobbin thread in a double-lock-stitch. A counter hook or counter point on the gripper assembly, which normally serves only to control movement of the loop from the main point, is formed on an underside with an auxiliary hook portion for drawing an extra thread length from the supply during each stitch and thus inhibiting bunching of the workpiece.

Rotary-gripper counter-hook for double-lock-stitch sewing machines

In a double-needle lock-stitch sewing machine, an assembly for arresting threads being drawn from the needles by an uptake stroke of a thread lever, thereby ensuring predetermined lengths of thread at the needles for an ensuing stitch, comprises a spring-loaded clamp disposed between the sewing lever and the needles. The clamp is periodically actuatable via a system of levers in the sewing-machine head by a cam mounted on the sewing-machine base and cooperating with a radial lug on a shaft driving a rotary thread gripper and bobbin holder. A spring-loaded plate engaging a pair of thread-tension control disks is pivotable by the lever system to release the disks upon actuation of the clamp. The clamp is particularly useful in controlling the length of a leading thread portion prior to beginning a sewing seam.

Controlled thread clamp device for needle threads

A bobbin and gripper assembly for a double-lock-stitch sewing machine has a stitch plate lying in a horizontal plane and a gripper rotatable in a horizontal plane below the stitch plate and receiving a bobbin housing. The latter is provided with a retaining finger which cooperates with abutments formed on the underside of the stitch plate to retain the bobbin housing against rotation with the gripper. In addition, the bobbin housing is held by a spring member which is effective to yieldably retard the bobbin against rotation in the direction of rotation of the gripper by friction therewith.

Gripper and bobbin assembly for double-lock-stitch sewing machine

A controlled braking device for the gripper-thread bobbin of a double lock-stitch sewing machine has a braking element which, by means of a brake piston or plunger in the axial bore of the spindle carrying the bobbin, is shiftable to engage the latter. The plunger is engaged by a rod reaching upwardly through an opening in the bottom of the spindle. The brake element is displaced laterally into engagement with the core of the bobbin or axially thereagainst.

Growing community of inventors

Leopoldshohe, Germany

Gunter Droste