Durkoppwerke Gmbh

Karl Nicolay

Klaus Hampel

Ernst V Osten-Sacken

A fabric feed for a sewing machine has a feed foot and a holddown foot that are vertically oppositely reciprocable between upper positions and lower fabric-engaging positions, and a continuously operating rotary drive with a rotating output whose rotary motion is transformed by an appropriate linkage into alternating reciprocation of the feed foot and the holddown foot. The feet are alternately engaged with and disengaged from fabric in the fabric-engaging position. On moving downwardly from their upper into their lower positions the feet are each first accelerated to a maximum speed reached when approximately midway between the upper and lower positions and thereafter are decelerated to an intermediate speed lying between zero and seven-tenths of the maximum speed reached when they attain the lower fabric-engaging position.

Upper fabric feed for a sewing machine

A fabric-transport device for a sewing machine above the stitch plate converts the rotary motion of the main upper drive shaft into reciprocating vertical motion of a pressure (hold-down) foot and a feed foot. The rotary motion is converted by a crank disc connected to a bell crank via an input crank. The bell crank swings a composite connecting rod, comprising a sliding link which interconnects the bell crank with a ternary link carrying the feet and comprising a guide bar for guiding the sliding link. The ternary link is spring-loaded against the stitch plate by a swingable arm and alternatingly lifts the pressure foot and the feed foot. The system provides for fast reduction of the velocity, towards zero velocity, of the feet as they depress to engage with the material to be sewn. SU

Upper fabric feed device for sewing machines

A workpiece is held down against a support surface by a holddown foot. Then a feed foot is brought into engagement with this workpiece with its displacement speed decreasing continuously and uniformly until the feed foot comes to a stop against the workpiece, pressing it against the support surface. Thereafter the holddown foot is raised away from the workpiece and the feed foot slides the workpiece a predetermined distance along the surface toward the sewing station. The holddown foot then is brought into engagement with the workpiece on the surface, again with its speed decreasing uniformly and continuously until it comes to a stop on the workpiece. The feedfoot is lifted away from the workpiece and brought back into a position to advance it again. Each of these feet is carried on a rod pivoted of a ternary link guided on a frame and having its remaining pivot connected via a rigid lever also pivoted on the frame and oscillated back and forth by an eccentric arrangement operated by the drive shaft of the sewing machine.

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Bielefeld, Germany

Karl Nicolay