Patent GB-915822-A (GB)
Title: Program control for sewing machines
IPC: D05B21/00
Filed: 1961-07-10
Abstract: 915,822. Sewing-machines. SINGER MANUFACTURING CO. July 10, 1961 [July 22, 1960], No. 24820/61. Class 112. [Also in Group XXIV] A sewing-machine work-holding frame movable along two co-ordinates at right-angles to one another is moved by means comprising a driving member, a driven member, a retractable element carried on the driving member to provide a positive driving connection between the driving and driven members, a punched control element disposed between the driving and driven members, and means for shifting the control element in timed relation with the stitch-forming means for moving the apertures in the control element into registry with the connection element to control operation of the driven member in accordance with the arrangement of apertures in the control element. A sewing-machine having a lower arm 12 and an upper arm 13 is mounted on a base member 30 which is in turn fixed to a table top 31. The machine is driven by a motor 17 via a belt 18 which can be shifted to engage any one of three pulleys 21, 22, 23 mounted on the upper arm shaft 20. Pulley 21 is a loose pulley, and pulleys 22 and 23 are adapted to drive the machine at reduced and full speeds, respectively. Belt-shifting is effected by a fork 27 on the inner bar 24 of a pair of bars 24, 25 slidable on pins 26 projecting from arm 13. Bars 24, 25 are releasably coupled together by a detent 281 provided on one arm of a lever pivoted on bar 25 and biased into a notch in bar 24 by a spring 282, the other arm of said lever being provided with a handle 280. A spring 165 biases bar 24 to the machine-stopping position. A pin 160 on the outer bar 25 is engaged with one arm of a lever 162 pivoted on a fixed bracket 163. A follower roller 167 on the other arm of lever 162 is biased by a spring 166 against a rotatable cam 168 formed with peripheral stations having one of three radii corresponding to belt 18 engaging pulleys 21, 22 or 23, respectively. Base 30 is provided with ways 32, 33 on which is slidable transversely of the arms 12, 13 a frame 34 provided in turn with ways 35 on which is slidable longitudinally of the arms 12, 13 a carriage 37 provided with a flat horizontal plate 38. Work is secured between the plate 38 and a frame 40 which is pivoted to lugs 39 on plate 38 and is locked against the latter by clamping handles 43. A lead screw 50, journalled` in base 30, engages a nut 52 on the carriage 37, and is driven by a shaft 54. A lead screw 51, engaging a nut 53 on frame 34, is driven via a right-angle gear unit 55 by a shaft 56. The movements of the belt-shifting lever 162 and the rotation of the shafts 54 and 56 in both directions are controlled in a predetermined manner by means of a perforated tape 60 to produce a desired pattern of stitching. The machine is arranged to run at high speed for straight stitching longitudinal of or transverse to the arms 12, 13, and to operate at low speed for diagonal or curved stitching. The feed-shafts 54, 56 are braked by an adjustable brake block 290 at low speed to prevent over-run, and run freely at high speed. A brake-releasing cam 295 is actuable by a sprocket 296 engaged by a chain 297, the ends of which are connected respectively to a spring 298 and one arm of a bell-crank lever 299. The other arm of the latter is connected by a link 300, via a pin-andslot connection 301, to the lower arm of the belt-shifting lever 162, the arrangement being such that lever 299 is rocked to release brake 290 when belt 18 engages the high speed pulley 23. The tape 60 is formed with a middle row of regularly-spaced drive holes 64, two rows of holes 65 and 66 on one side of the holes 64 for controlling the rotation of shaft 56 in opposite directions, two rows of holes 67 and 68 on the other side of the holes 64 for controlling the rotation of shaft 54 in opposite directions, and an outer row of holes 69 for controlling the movements of the belt-shifting lever 162. Tape 60 extends loosely between reels 70 which are fast on shafts 71 journalled in a frame 72 carried on the table top 31. The shafts 71 are interconnected by a belt 74, and one shaft 71 is driven by a belt 76 from a shaft 78 which is journalled in spaced plates 80 fixed to a base-plate 99 mounted by means of bolts 100 and resilient washers on the table top 31. Shaft 78 is coupled to the output shaft of a reversing unit 82 controlled by a lever 83. The input shaft of unit 82 is driven by a belt from a shaft 88 which in turn is driven by gears 88 and 99 from the arm shaft 20. Tape 60 passes between a hollow drum 102 secured to shaft 78 and a series of tape-supporting plates 130 carried by plate 99 and clamped between the plates 80. Drum 102 is provided with a middle row of tape-driving pins 104 adapted to engage the holes 64, and is also formed with five rows of holes 105 to 109 corresponding to the holes 65 to 69, respectively. A pin 110, slidably fitted in each one of the holes 105 to 109, has a head 111 disposed within drum 102, and is urged outwardly by air pressure supplied to the interior of drum 102 via a hose 113 from an air compressor 114. The holes 65 to 68 are so arranged that any of the pins 110 aligned therewith will pass through these holes to engage between the teeth of respective sprocket-wheels 135 to 138. Sprocket-wheels 136 and 137 are fast with respective shafts 140 coupled by gears 141, 142, 143 to shafts 56 and 54, respectively, for driving these in one direction. Sprocket-wheels 135 and 138 are fast with hollow shafts 144 journalled on the shafts 140 and coupled by gears 145, 146 to shafts 56 and 54, respectively, for driving these in the opposite direction. The cam 168 controlling the movements of the belt-shifting lever 162 and formed with peripheral stations of three different radii corresponding to the engagement of belt 18 with pulleys 21, 22 and 23, respectively, is fast with a shaft 169 driven by gearing 171 to 174 from an axially-slidable shaft 175, and the arrangement is such that half a revolution of shaft 175 shifts cam 168 from one station to the next station. Cam 168 is arranged to stop the machine at the end of a stitching cycle, which may correspond either to a complete revolution of cam 168 or to a sub-multiple of such a revolution. Shaft 175 is driven through successive half-revolutions by a half-revolution clutch device actuated by the tripping of a latch lever. A pulley 180 journalled on shaft 175 is driven continuously by a belt 181 from a motor 182, and a spring 185 tends to inter-engage clutch surfaces on pulley 180 and a collar 183 fast on shaft 175. A collar 184 fast on shaft 175 carries two diametricallyopposed stop-lugs 187, 188 disposed at different distances from the axis of shaft 175 and adapted to co-operate alternatively with a stop cam projection 189 on a clutch control lever 190 for separating collar 183 from pulley 180. When lever 190 is turned to release one of the lugs 187, 188, the projection 189 moves into the path of the other lug which engages the projection to stop shaft 175 after the latter has turned through half a revolution. Lever 190 engages a pin 195 projecting radially from a rod 196 slidable axially in fixed bushings 197. A pair of bushes 203, spaced along rod 196, are adapted to slide on the latter by means of an eccentric 204 on shaft 175. Springs 107, 208 are interposed between the bushes 203 and respective collars 205, 206 fast on rod 196. As shown, lug 187 engages projection 189 and spring 207 is compressed to bias a collar 202 fast on rod 196 against the right-hand side of a latch lever 199. When the latter is tripped, against the bias of a spring 201, to release collar 202, spring 207 moves rod 196 to the left to position collar 202 on the left-hand side of lever 199 and to swing lever 90 for freeing lug 187. Shaft 175 then rotates half a revolution till lug 188 engages projection 189, and eccentric 204 moves the bushes 203 to compress spring 208 and thereby bias collar 202 against the left-hand side of lever 199. A link 214 connects lever 199 to one arm of a bell-crank lever 212, the other arm of which is in the form of a sensing finger 211 underlying the row of holes 69 in tape 60. A pin 110 engaging finger 211 thereby swings lever 212 to trip lever 199. The latch lever 199 is also adapted to be tripped, for starting the machine, by a starting- handle 230 pivoted on the upper arm 13. Handle 230 is connected by a link 232 to a curved arm 233 rigid with a gear segment 234 pivoted at 235. Segment 234 meshes with a gear 237 journalled on a stub shaft 238. Also journalled on shaft 238 are three discs interconnected by a pin 246 which is connected by a link to the control lever 83 of the reversing unit 82. The inner disc is formed with two diametrically opposed shoulders 245, the middle disc is formed with two diametrically opposed recesses 248, and the outer disc carries two diametrically opposed cam lugs 258. A pawl, pivoted on a lug 233 rigid with gear 237, is biased by a spring into engagement with one or the other of the shoulders 245. When handle 230 is moved between a pair of fixed stops, pawl 242 turns the interconnected discs through half a revolution, and the handle 230 on release is returned to its original position by a spring 236, the pawl also returning to its original position to engage the other shoulder 245, and the recesses 248 being engaged in turn by the nose of a spring-biased locking lever 250. Link thereby operates the unit 82 to reverse the drive to the tape 60, and one of the lugs 258 co-operates with a follower nose 260 of a spring-biased lever 259 to swing the latter for tripping the latch lever 199 via a cable 220 and a lever 221. While the machine is operating, a lug 270 on link 232 is positioned opposite a lug 272 on a locking-lever 271 to prevent actuation of the handle 230. Lever 271 is biased by a weak spring 273 against a stop-screw 274 on a lever 275, the latter carrying a roller 277 which is biased by a stron