Patent GB-1027554-A (GB)
Title: Improvements in or relating to sewing machines
IPC: D05B27/04
Filed: 1963-07-15
Abstract: 1,027,554. Sewing machines. G. M. PFAFF A.G. July 15, 1963 [July 16,1962], No. 27902/63. Heading D1G. A sewing machine, especially adapted for sewing leather, comprises a feeding foot disposed behind the needle, a presser foot disposed in front of the needle and having a horizontal sole and a verticle flange or guide serving to bend downwardly the marginal edge of a workpiece, and a lever adapted to oscillate perpendicularly to the feed direction between said vertical flange and the needle so as to fold under the bent down marginal edge of the workpiece. A needle bar 6, carrying a needle 5, is slidable in a frame 28 pivoted at 29 to the machine frame and oscillated, via a pin 33, in the feed direction. A pin 35, depending from frame 28, is slidable in a sleeve 36 rigid with a feeding foot 39 disposed behind the needle 5. A presser foot 50, disposed in front of needle 5, has a horizontal flange 52 engaging a horizontal surface on a thrust plate 12 and a vertical flange 54 spaced from a vertical surface of thrust plate 12 to bend downwardly the margin of a workpiece 92. Presser foot 50 is rigid with the lower end of a hollow bar 48. A rod 56, slidable in the latter, carries at its lower end a block 59 universally pivoted to one end of a pin 60, the other end of which is pivoted to a pin 38 rigid with sleeve 36. The upper end of rod 56 abuts a block 57 biased downwardly by a leaf spring 58. The upper end of bar 48 rigidly carries a block 49 to which is pivoted at 47 a two-armed lever 46. One of the latter carries a roller 55 and the other arm is connected by a linkage 41-45 to an eccentric 40 on a rotary shaft 4. The arrangement is thereby such that roller 55 in its highest position, when oscillating with lever 46, engages block 57 to raise rod 56. Block 59 thereby engages the lower end of bar 48 to raise the presser foot 50, and the feeding foot 39 is also raised via the pins 38, 60. Feeding foot 39 co-operates with a feed dog 19, Fig. 2 not shown, carried at the upper end of a bar 20 pivoted intermediately to a block 23 slidable in a fixed guideway 22. The lower end of bar 20 is pivoted to one end of an arm 24 forked to embrace a rotary feed-lift cam 27. The other end of arm 24 is pivoted to a crank 26 on an oscillatory feedadvance shaft 25. An oscillating knife 73 passes through a slot 53 in flange 54 of the presser foot and an aligner slot in throat plate 12 to slit the turned-down edge of the workpiece 92 once for every three stitches. Said edge is then folded upwardly against the workpiece by an oscillating finger 61 which cooperates for this purpose with flange 52 immediately in front of needle 5. Finger 61 is carried by a bell crank lever 62 connected by a link 64 to one end of an arm 65, Fig. 5 not shown, which is pivoted on a spindle 66 and carries at its other end a pin 69 co-operating with a cam groove 67 formed in a driven ear 68 journalled on a shaft 71. Knife 73 is carried by a bell crank lever 74 connected by a link 75 to one end of an arm 76, Fig. 5. pivoted on spindle 66. The other end of arm 76 is formed with a slot 77 slidably receiving a block 82 on which is pivoted a block 83 slidable in a vertical slot 85 formed in a disc 86 journalled on shaft 71. A spring 87 biases disc 86 clockwise, whereby a fixed pin 88 abuts one end of a peripheral notch 89 in disc 86, and block 82 is positioned at the inner end of slot 77. An arm projecting from disc 86 is connected by a chain 90 to a treadle, operation of which turns disc 86 counterwise and thereby serves to shift block 82 into engagement with a slot 79 formed in an arm 78 which is pivoted on spindle 66 and is oscillated by co-operation of a pin 80 thereon with a cam groove 81 in gear 68.