Patent GB-1061824-A (GB)
Title: Automatic machines,button-hole sewing and cutting machine
IPC: D05B65/00
Filed: 1965-02-10
Abstract: 1,061,824. Sewing machines. DURKOPPWERKE A.G. Feb. 10, 1965 [Feb. 10, 1964], No. 5725/65. Heading DIG. A buttonhole sewing machine comprising stitch-forming means rotatable about a vertical axes, buttonhole-cutting means displaced from said axis, a movable work-supporting plate provided with a work clamp, an auxiliary work clamp, and cutting means for the lower and filler threads, is prodded with a first safety device permitting thread cutting only when the machine is stationary and comprising a stop carried by the work-supporting plate to lock a control member of the thread-cutting means and a second safety device preventing starting of the machine during actuation of the thread-cutting means. The machine comprises a needle 6 and a looptaker rotatable about a vertical axis Y-Y, a work-supporting plate 7 and associated presser feet 13, 14 movable inwardly when the machine is started and an auxiliary presser foot 77 which descends at the end of a sewing operation, when plate 7 moves outwardly, the machine stops, and the needle 6 and presser feet 13, 14 rise. The lower thread and filler cord are then cut by means actuated when a shaft 23 is rotated via a crankarm 26, coil spring 28, chain 30 and a treadle. Presser foot 77 is pivoted to an arm 76 releasably secured to a lever 71 pivoted at 72 to plate 7. An arm 82, also pivoted at 72, is spring biased against pin 85 rigid with lever 71, and carrier pins 86 and 87. At the end of a sewing operation, when plate 7 moves to its outer position, pin 86 engages an adjustable fixed abutment 70 whereby arm 82 and lever 71 are turned to lower presser foot 77 on to a cooperating grooved surface 78, and to engage pin 87 with a notch in a spring-biased arm 88, pivoted to plate 7, for retaining presser foot 77 in the lowered position. The thread-cutting means comprise a blade 18 rigid with a plate 20 slidable in a fixed guideway 21 and normally retracted from the sewing position, and a co-operating blade 19 pivoted at 22 to plate 20. A slot 56 in plate 20 is engaged by a pin 54 on an arm 53 pivoted on a pin 48 journalled on a plate 49 rigid with plate 7. A slot 57 in the tail of blade 19 is engaged by a pin 52 on an arm 51 rigid with pin 48. A pin 59 on arm 53 abuts the edge of arm 51 under the bias of a spring 58 interconnecting arms 51 and 53. An arm 47, rigid with pin 48, is embraced by a pair of abutments carried by a compound arm 35, 38 which is slidably pivoted to the machine frame and is pivoted at one end to a crank arm 33 on shaft 23. Rotation of the latter by means of the treadle thereby serves to swing arms 47, 51, 53, when plate 20 is moved by pin 54 towards the sewing position till a pin 61, adjustably carried by arm 53, engages an abutment on plate 49, and arm 51 then moves further to swing blade 19 via pin 52 for cutting the thread. A crank arm 105 on shaft 23 engages a notch 104 in the lower end of a verticallyslidable plate 99, whereby, on rotation of shaft 23, the upper end of plate 99 releases a spring- biased arm 106 pivoted on plate 7, when a notch 106' in arm 106 engages a rod for blocking the movement of a starting lever 91. A pin 98 on plate 99 engages a slot 97 in one arm of a lever 92 pivoted at 93 to the machine frame. The other arm of lever 92 carries adjustably at its upper edge a plate 94 adapted to be engaged by an abutment 89 adjustably mounted on plate 7, when the latter moves inwardly at the start of a sewing operation, for holding plate 99 raised to prevent actuation of the thread-severing means. A pin 88' on arm 88 also engages plate 94 to raise arm 88, whereby pin 87 is released and lever 71 swings under spring bias to raise presser foot 77. In a modification shaft 23 is turned, to effect thread cutting, by means of a solenoid energised via a switch adapted to be closed by an abutment on plate 7.