CNC controlled buttonhole sewing machine

A CNC controlled buttonhole sewing machine, comprising

• a needle (6), which is drivable via an arm shaft (4);
• an x-y table (7, 7′),
• which is movable by an x drive (8) in an x direction and by a y drive (9) in a y direction, and
• which supports a first and a second work piece clamp (17a, 17b, 17″b), the first and second work piece clamps (17a, 17b, 17″b) being mounted for displacement relative to each other, and
• which comprises a sliding drive (12, 12′) for displacement of the work piece clamps (17a, 17b, 17″b) from an initial position of spread by a length of spread d into a final position of spread;
• and
• a control unit (32) for control of the drives (8, 9, 12, 12′) for displacement of the x-y table (7, 7′) prior to the start of production of a buttonhole seam (24),
• wherein the sliding drive (12) at least of the first work piece clamp (17b, 17″b) is an electric positioning motor;
• and
• wherein the control unit (32) includes a data storage (33) with data stored therein for displacement of the at least one first work piece clamp (17b, 17″b) by a given length of spread d.