Chain stitch sewing mechanism
In a chain stitch sewing mechanism with a sewing head movable parallel to the sewn material plane, including a needle rod with a needle drive for reciprocating a thread carrying needle, a catcher drive for reciprocating a needle shaped thread catcher with an open catching hook. The needle and thread catcher have movement paths forming a sharp angle with one another whose apex lies beneath the sewn material plane and the needle and catcher being so controlled such that a loop formed by the withdrawal of the needle is caught by the thread catcher and pulled through the material. A thread puller on a movable thread arm is moved towards the thread catcher and cooperates with the thread catcher for deflecting the loop hanging off the thread catcher at an angle to the movement path of the thread catcher toward the side opposite to that of the hook opening.
1. A chain stitch sewing mechanism with a sewing head movable parallel to a sewn material plane, which sewing head includes a needle rod for a thread carrying needle, a needle drive for linearly moving the needle rod back and forth at an angle to the sewn material plane, a needle shaped thread catcher provided with an open catching hook and a catcher drive for linearly moving the thread catcher back and forth at an angle to the sewn material plane, with the movement path of the needle and of the thread catcher forming a sharp angle α with one another whose apex S lies below the sewn material plane and with the needle drive and the catcher drive being so controlled that a thread loop formed by the withdrawal of the needle out of the sewn material and located below the sewn material is caught by the thread catcher and pulled by the thread catcher upwardly through the sewn material, wherein a driven thread puller is associated with the thread catcher, which thread puller has an arm movable at an angle to the movement path of the thread catcher into the path of the thread loop hanging on the thread catcher and whose drive is so controlled that the arm near the uppermost position of the thread catcher deflects the thread loop hanging from the thread catcher at an angle to the movement path of the thread catcher and toward the side opposite to that of the hook opening.
2. A chain stitch sewing mechanism according to claim 1 , wherein the arm of the thread puller is made from a wire shaped bow, which bow extends essentially parallel to the sewn material plane and is so supported that its free end upon actuation of its drive moves along—as seen in a perpendicular projection onto the sewn material plane—an annular closed path.
3. A chain stitch sewing mechanism according to claim 1 , wherein the movement path of the thread catcher is oriented essentially perpendicularly to the sewn material plane and that the movement path of the needle and of the thread catcher lie in a plane at an angle to the advancement direction A of the sewing head and perpendicular to the sewn material plane.
4. A chain stitch sewing mechanism according to claim 1 , wherein the angle α between the movement paths of the thread catcher and of the needle has a value of about 30° to 60°.
5. A chain stitch sewing mechanism according to claim 1 , wherein at least the needle and the thread catcher together with their individual drives are arranged on a frame located in the sewing head housing and movable back and forth parallel to the advancement direction A of the sewing head.