Patent GB-1077510-A (GB)
Title: Automatic buttonhole sewing machines
IPC: D05B35/12
Filed: 1966-02-17
Abstract: 1,077,510. Sewing machines. E. BECKER and K. NOTZ, [trading as FIRMA QUICKROTAN BECKER & CO.]. Feb. 17, 1966 [Feb. 18, 1965], No. 6919/66. Heading D1G. An automatic buttonhole sewing machine comprises clamp means for feeding the work between successive button hole sewing operations, means movable back and forth by the distance between successive buttonholes, means for respectively coupling and uncoupling the clamp means to and from the movable means during movement of the latter in opposite directions, and means for controlling the movements of the movable means. As shown, a sewing machine 9 is driven by a continuously-running motor 1 via a clutch engaged by the energisation of a coil 4. To start the machine a pedal 5 is depressed for initially closing contacts 7 for energising a coil 8 to effect the lowering of a presser foot 13 via a linkage 12. Further movement of pedal 5 closes contacts 6 for energising coil 4. A safety switch 14 has contacts preventing energisation of coil 4 until the presser foot is lowered, and further contacts preventing the energisation of coil 8 until the sewing machine is stopped. The work is fed by a clamp 11 which co-operates with a table 10. A bar 15, rigid with clamp 11, adjustably carries a pair of pins 21, 22 spaced apart at the distance a between successive buttonholes. Upon starting of the sewing machine, clamp 11 moves forwards in the direction B to sew the first side G of a button hole between the points S1 and S2. Clamp 11 then moves to the left through a distance b equal to the width of a buttonhole to position the needle above a point S3. Finally clamp 11 moves rearwards in the direction C to sew the other side H of the buttonhole between points S3 and S4, when the sewing machine stops and the presser foot 13 rises. During completion of the rearward movement of clamp 11, pin 21 enters a socket 20 carried by a rod 16 slidable in bearings 17, 18. Rod 16 is coupled by a connecting rod 36 to a crank on a rotary shaft 33, the throw of said crank being adjustable to half the distance a. Shaft 33 is rotated by the energisation of a magnetic clutch 29, the driving component of which is continuously rotated via a belt 30 from motor 2. Energisation of clutch 29 is controlled by a rotatable switch cylinder 32 driven by the sewing machine. The arrangement is such that after the completion of side H, clutch 29 is energised, and shaft 33 is stopped by a limit switch associated therewith after rotating through 180 degrees. Clamp 11 thereby moves leftwards through a distance a to position the needle above a point S5. A cam 23 on rod 16 simultaneously closes a switch 24 to start the sewing machine, a safety switch 42 preventing starting until presser foot 13 has been lowered. The sewing machine then sews the respective sides K and L of the second buttonhole. On completion of the first side K, when pin 21 is disengaged from socket 20, shaft 33 is again rotated through 180 degrees, whereby rod 16. moves rightwards through an idle stroke, and on completion of side L pin 22 enters socket 20. A similar sequence of operations then follows for sewing the third and final buttonhole. For sewing of the next workpiece, clamp 11 moves from right to left and the previously idle strokes of rod 16 become the working strokes. The number of pins carried by bar 15 is one less than the number of buttonholes sewn.