Patent GB-1055529-A (GB)
Title: Pneumatic concatenation of under thread with needle thread to form stitches
IPC: D05B57/16
Filed: 1965-07-07
Abstract: 1,055,529. Sewing machines. SINGER CO. July 7, 1965 [July 9, 1964], No. 28894/65. Heading D1G. Stitching is effected by projecting a loop of thread through a workpiece and utilizing a stream of air to pass a thread through said loop. As shown, a horizontal tube is formed with a transverse cut to provide end portions 35,36 having confronting openings 37,38 separated by a back wall portion 60, the front wall of the tube adjacent the openings being formed with a recessed portion 171. To initiate stitching, the needle passes through the opening 105 in the throat plate 32 and the loop 51 of thread cast when the needle rises is engaged by an oscillating thread spreader 34 to press one limb of the loop against surface 60 and the other limb against surface 171 adjacent opening 38. Air then flows from tube 36 to tube 35 to carry the free portion 50 of the thread into the latter, said portion then constituting the locking thread during subsequent stitch forming. After the next needle penetration, when the thread loop limbs are engaging surfaces 60 and 171, air flows from tube 35 to tube 36 to pass portion 50 through the loop 51 and into tube 36. When spreader 34 releases loop 51 the stitch is set by action of the take-up on the upper thread, and the tensioning of portion 50 by the air stream. Portion 50 may be returned to tube 35 by reversal of the air stream before the next needle penetration for the formation of normal lock stitches. As described, however, portion 50 is passed through the next-formed loop in the reverse direction from tube 36 to tube 35. To provide a longer portion 50, several needle penetrations may occur before stitching commences and while the work is stationary. It is stated that concatenation by means of an air stream can be used also to produce chain stitching. In a modified group stitching machine as described in Specification 875,326, the tubes 35 and 36 are connected by respective ducts 40 and 39 to valve means 41 containing a rotary member 209 driven by 2 to 1 reduction gearing 200,201 from the arm shaft 74, whereby ducts 39 and 40 are connected alternately to a com- Dressed air duct 217 and an exhaust duct 43. The loop spreader 34 is driven by gears 184,185 from a bed shaft 186 oscillated by linkage 188, 189, 190 from an eccentric 191 on shaft 74. A rotary cam disc 77 serves to actuate the work clamp 85 via followers 83,84. The machine is started by manual actuation of a lever 93, and is stopped by co-operation of a follower with cam lugs on disc 77. A follower co-operates with a cam groove in disc 77 to actuate a bar 96, immediately prior to stopping, to position a pair of knife blades 104,106, Fig. 4, not shown, adjacent the needle aperture 105, and to engage a thread separating finger 103 rigid with blade 104, in the needle thread loop. On manual actuation of a lever 88 to raise the upper jaw of clamp 85, bar 96 is further actuated by a linkage 98,99 for severing the threads. A thread tensioner 120 comprises a rod 126 slidable in a fixed sleeve 123 and provided at its ends with respective flanges 133 and 134. A yoke member 130 straddles sleeve 123 and is slidable on rod 126. A pair of threadtensioning discs 135,136 are slidable on rod 126 between flange 134 and one arm of member 130. A compression spring 132 is disposed between the other arm of member 130 and flange 133, Rod 126 is pivoted to one end of a rod 140 which is slidably mounted in the machine frame and is biased towards rod 126 by a compression spring 143. The other end of rod 140 slidably carries a sleeve 144 rigid with a depending plate 145 and biased away from said other end by a compression spring 148. A vertical pivoted shaft 152 carries at its upper end a pair of diametrically-opposed fingers 150, 151, Fig. 7 (not shown), and at its lower end a follower finger 153, which, in the stationary condition of the machine, engages a cam plate 157 secured to the edge of disc 77 to position both fingers 150,151 abutting plate 145. The arrangement is such that discs 135,136 are then separated to relive the thread tension. Plate 157 is provided with three cam lugs 158, and the arrangement is such that, when the machine is started, no movement is initially imparted to clamp 85, and finger 153 is engaged by the lugs 158 after each of three successive needle penetrations to actuate rod 140 via finger 151 to clamp the thread between discs 135,136, whereby the take-up 76 draws thread from the supply to serve as locking thread. When finger 153 leaves plate 157 and engages the edge of disc 77, movement is imparted to clamp 85, and plate 145 is engaged by finger 150, positioned closer to the axis of shaft 152 than finger 151, for applying normal tension to the thread.