Importance

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Abstract

Method and apparatus for aligning fabric as it is advanced in a prescribed direction toward a sewing machine such as a double overlock seamer for stitching pants. Photosensitive devices sense displacement of edges of upper and lower fabric plies relative to a desired alignment line. Error signals are produced when either ply edge is displaced from the desired alignment line. Friction wheels responsive to the respective error signals guide each ply toward the desired alignment line as it is advanced toward the sewing machine. Each friction wheel pivots about an axis perpendicular to the ply and is controlled by a stepper motor. Each friction wheel is movable between an operating position in which it is biased against the respective fabric ply, and a retracted position for insertion or removal of fabric. The pressure applied to the fabric ply by the friction wheel is adjustable. A centering device aligns each friction wheel with the direction of fabric movement toward the sewing machine when no fabric is present in the apparatus.

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First Claim