Patent GB-1054844-A (GB)
IPC: D05B33/00
Abstract: 1,054,844. Sewing machines. ZAVOD Y BOZENY NEMCOVE, PLETARNY, NARODNI PODNIK. July 6, 1964 [July 5, 1963], No. 27728/64. Heading DIG. A workpiece in the form of an endless band is stretched on a holder moved at time-controlled intervals to and away from a stitching position, and a sewing machine is also moved at similar timecontrolled intervals to and away from said stitching position, stitching being performed on the workpiece when the holder and sewing machine are both in said stitching position. A sewing machine 4 is slidably supported on bars 2 carried by a stand 1. A pin 7, rigid with the sewing machine, engages a cam groove 8 in a disc 9 fixed to the upper end of a shaft 10. Fig. 1, not shown, driven by a motor 24 via a magnetic clutch 25. The lower end of shaft 10 is connected by linkage 11 to 17 to the lower end of a shaft 18, the upper end of which carries a square plate 19. From each side of the latter project bars 42,43 carrying a bracket 40 in which is journalled rollers 39, 41, the uppermost parts of which lie in a plane coincident with that of the needle plate of the sewing machine. Each side of plate 19 also supports a depending bar 44, Fig. 1, slidably carrying a sleeve 45, a bracket 47, rigid with the latter, journals a roller 46 positioned between the rollers 39,41. A tubular workpiece supported by the rollers 39,41 is tensioned therebetween by the roller 46 engaged within the workpiece. A motor 49, Fig. 1, drives a vertical screw-threaded shaft 52 carrying a nut 53 having an extension 54 adapted to engage an adjacent sleeve 45, whereby operation of motor 49 serves to raise nut 53, and the associated sleeve 45 and roller 46, to a position in which sleeve 45 is held by a catch 102 releasable by a handle 103. Motor 24 also drives a shaft 30 via an electromagnetic clutch 26. A pulley 33, slidable on shaft 30, is connected by a belt 34 to the driving pulley of the sewing machine, and also to a pulley 36 which is connected via a gearbox 37 to a conical clutch member 38 which engages a corresponding recess in a roller 39 when the sewing machine is advanced to its operative position. Upon energization of clutch 25, the sewing machine moves towards its operative position and plate 19 is turned through 90 degrees to present a fresh workpiece to the sewing machine. A cam surface 59 on frame 1 also engages the end 58 of a lever 57 to raise the presser bar 55, Fig. 3, not shown. When the sewing machine reaches the operative position, end 58 moves clear of surface 59 whereby the presser bar is lowered, a limit switch 75 is actuated to de-energize clutch 25, and a limit switch 82 is actuated to energize clutch 26 for driving the sewing machine and clutch member 38. During the sewing operation motor 49 is operated via limit switch 75, whereby the associated sleeve 45 is raised and latched, limit switches associated with nut 53 serving to return the latter to its lowered position. At the end of the sewing operation a foot 64, Fig. 3 engaging the work is raised by a longitudinal seam in the workpiece, whereby a pawl 65 tilts a segment 66 carrying a mercury switch 67 to dose the latter, segment 66 being held in the tilted position by a catch 70. Closures of switch 67 serves to energize clutch 25 whereby the sewing machine moves away from the operative position, clutch 26 being de-energized by switch 82 and the sewing machine is halted in the fully-retracted position by a limit switch 76 which also activates a time-delay circuit, whereby clutch 25 is re-energized after the lapse of a predetermined interval of time. Catch 70 is tripped, to release segment 66, by engagement with an abutment 71, Fig. 3. During the retraction of the sewing machine, a switch is actuated to energize a solenoid 94 to effect thread severing. In the event of thread breakages, motor 24 is switched off.