Patent GB-709531-A (GB)
Title: Improvements in sewing machines
IPC: D05B73/12
Filed: 1952-01-09
Abstract: 709,531. Sewing - machines. UNION SPECIAL MACHINE CO. Jan. 9, 1952 [Jan. 29, 1951], No. 649/52. Class 112 In a sewing-machine having a main frame with a longitudinal driving shaft, a downwardly-extending hollow member at one end of the frame, and a tubular worksupporting arm projecting laterally from the lower end of the hollow member, a four-motion looper in the arm receives loop-seizing and -shedding movements from the driving shaft through connections which include a rock member mounted in the hollow member of the frame. The machine described has several needles co-operating with a single looper and means for laying a surface thread, and the Specification includes claims to work produced by such a machine. Means for trimming the work edges may be provided. Stitches and seams. Fig. 24 shows the under side of a four-thread butt seam produced by the machine, the work being fed upwards in this Figure. Each loop of the looper thread passes through loops of all the needle threads 218...221, and its end 211 passes round the next loop of the needle thread 218, the body of the loop having one limb 210 straight and the other formed into bights 214 passing round the next loops of the needle threads 219...221. The upper side of the work shows four lines of stitching, with the surface thread laid back and forth transversely under the stitches, passing straight across in one direction and enclosing the loops of two needle threads at each reversal of direction. A threethread lap seam of similar form, with the middle line of stitches passing through both work-pieces, is also described. A seam is formed as follows:-two needles descend through a loop of surface thread held by the thread-laying devices 'and the remaining needle or pair of needles descends behind the loop, all the needles passing through a loop of the looper thread held in their path by the looper; the looper then withdraws and enters the needlethread loops on the opposite side of the retreating needles, after which the work is fed (drawing out the loop end 211 and the bights 214) and the cycle repeated. Frames; multiple-needle machines; needle guards. The feed-off-the-arm machine shown has a frame comprising a base 10, Figs. 2 and 3, a horizontal upper portion 11 with a projecting sewing head 15 and a depending hollow part 12, and a tubular work arm 13 which has an upwardly extending hollow part meeting the part 12 on a horizontal plane; the arm 13 may be integral with the part 12. A main shaft 18, with driving pulley and hand-wheel 19, extends along the frame portion 11 and has a needle-actuating crank 33, eccentrics 139, 69, and a crank 58 at the end. The crank 33 is connected by a pitman 32 with a lever 30 which is linked to a block 28 on the needle-bar 26 carrying three needles 27; the needle threads are led through holes in the oppositely inclined heads 164, 165 of relatively-adjustably guides, and then through holes in a take-up arm 170 fixed on the lever 30 on their way to the needles. The looper 34, Fig. 8, has a thread eye 194 in its heel whence the thread passes along a wide shallow groove in the outer face of the looper to the eye near its point. The base of the looper is formed with a pin which is clamped in a member 38 secured to a shaft 41; a needle guard 73, curved similarly to the looper, is also fixed to the shaft 41. At the opposite end the shaft 41 passes through a sleeve 44, in which it can oscillate but not slide, and has a crank 47 whereby it receives loop-seizing and - shedding movements from the crank 58 on the main shaft 18; the cranks 58, 47 are connected by a pitman 57, Fig. 2, a rocking member 52 mounted on a horizontal pivot in the frame part 12, and a link 49, the member 52 being so formed and arranged that its lower arm is substantially in line with the link 49 at one end of its movement. with the result that the loopshedding and -seizing movements of the looper are very fast, each being substantially completed in about one-twelfth of a revolution of the shaft, so that the line joining the points of the needles needs to be relatively little inclined and the needle stroke need not be long. Needle-avoiding movements are imparted to the looper through the sleeve 44, which is reciprocated in a bearing 43 by a link 61 adjustably connected to one arm of a three-arm lever 64 oscillated by a pitman 68 from the eccentric 69; rotation of the sleeve 44 is prevented by a forked lug 71 on it engaging flats on a pin 72. The looper thread is led from its tension device through two guides 185, Fig. 2, between which it passes over a pair of take-up cam discs 190 on the shaft 18; a finger 191 lies under the thread to prevent its being carried round with the discs. Differential feed by dogs. Main and auxiliary feed-dogs 127, 128, Fig. 8, are carried by feed-bars 130, 133, the dog 127 being vertically adjustable. The feed-bars are separately slidable on a block 131b rockable on a pin 131 which has an eccentric portion so that the height of the block may be adjusted by turning the pin; the inner end of the feed-bar 133 is turned sideways to form a lug which is slidably engaged with a pin 131 provided on the end of the feed-bar 130, so that both bars have the same rocking movement, derived from an eccentric 139 on the main shaft through a pitman 138 engaging a ball on the end of the pin 134. The feed movements are derived from the third arm 141 of the looper-shifting rocker 64, this arm being slotted for adjustable connection to a link 143 which oscillates an arm 145 of a rocker on a shaft 147; another arm of this rocker is connected by a link to the main feed-bar 130, and the arm 145 is slotted for adjustable connection to a link 154 actuating the auxiliary feed-bar 133, the adjustment of this connection being effected by a finger lever 160 (outside the frame) through an arm 159 and a link 156. Presser-bars; presser-feet; trimming; surface threads, concatenating with stitches. The presser-bar 86, Figs. 2 and 3. passes through a sleeve 84 which is oscillatable but not slidable on the presser-bar and which works in a bearing 85 in the machine head 15. The bar 86 is pressed down by a double leaf-spring 88, and is lifted by a treadle-operated lever 197, pivoted at 199, through a link 201 and a lever 202, 204 engaging the sleeve 84. The presser-foot 87 has two limbs between which the upturned edges of the workpieces can enter for trimming before reaching the stitching-point, and is formed with a shank 89 which carries the trimming means and part of the surfacethread-laying means and by which it is mounted on the lower end of the presserbar 86. To prevent rotation of the presserbar by reaction of the trimming means or with the sleeve 84, the presser-foot shank 89 has an arm 124 bearing against a member 126 fixed to the underside of the machine head 15, and the presser-bar 86 carries a forked arm 122 engaging flats on a fixed pin 123. The sleeve 84 is oscillated from an eccentric 77 on the shaft 18 by a link 79 connected to an arm 82 clamped on the sleeve, and a second, downwardlyextending, arm 113, Figs. 3 and 14, clamped on the lower end of the sleeve has a flat lower part 116 to which is clamped a curved trimming blade 115 with a cutting edge 118 co-operating with an adjustable leger blade 120 fixed on the presser-foot 87; the blade 115 has a finger 119 which rides on the blade 120 to guide the former blade. A surface-thread-laying arm 102 is fixed to the lower end of a spindle which is journalled in a part 104 of the presser-foot shank 89 and which has on its upper end an arm 105 connected by a link 107 with an arm 109; the latter arm is integral with an arm 95 which is clamped on the upper end of a vertical spindle mounted in a part 98 of the presser-foot shank and which is oscillated by a link 93 connected to an arm 91 inte-' gral with the sleeve 84. A hook-shaped arm 99 secured to the lower end of the lastmentioned spindle extends round the back of the presser-foot shank 89 and its end is formed with a downward barb to engage the surface thread. The thread-laying arm 102 has a finger 110 with a thread eye and a second, somewhat shorter finger. with no eye. On movement away from the position shown in Fig. 14, the arm 102' lays a length of thread from the previous set of stitches and the arm 99 advances across the front of the path of the needles 27 until its barb engages this length of thread; as the arm 99 then retires, it draws a loop of the surface thread back across the needles and the arm 102 advances so that its fingers hold one limb of the loop behind the two left-hand needles, The surface thread passes through a hole in the needle-thread guide 164, and through holes in an adjustable U-member 175 between the limbs of which works a controlling member 179 fixed to the block 28 on the needle-bar; the member 179 has upper and lower pulling fingers 183, 184. and an intermediate cam surface Specifications 294,824, [Class 112] and' 709,551 is referred to.