Patent GB-756818-A (GB)
Title: A machine for making bed sheets and the like
Inventor: MACISAAC JOHN THOMAS
IPC: D06H7/02
Filed: 1954-10-05
Abstract: 756,818. Sewing-machines. FIELDCREST MILLS, Inc. Oct. 5, 1954, No. 28621/54. Class 112. [Also in Groups VIII and XVI] A machine for producing large articles such as bed sheets in finished form from web material provided with woven selvedge, or already hemmed, along each longitudinal edge comprises means for successively drawing a predetermined length or blank from the web, cutting off said length, forming a first fold along each raw edge of the blank, forming a second fold in the raw edges while moving the blank transversely to the direction in which it was drawn off from the web, and sewing the folded edges to form the hems, the hem at one edge being made wider than that at the other. In the machine described means are provided for maintaining slack in the web sufficient to allow the required length to be drawn across the machine; for forming a certain amount of slack between the ends of the blank length before it is cut; for clamping the blank while it is cut and while the first folds are made; for feeding it relatively fast up to the stitching point and relatively slowly during the sewing; and for starting and stopping the sewing mechanism in accordance with the position of the blank. All the operations are automatically performed in sequence; in the machine described the various operations are produced by cams on a main motor-driven control shaft or shafts or by motors controlled by switches actuated either by such cams or by the movement of the work. Feeding web to machine.-The web W is drawn from a roll on a spindle 151, Fig. 1A, by a feed roller 157 placed at some height above the machine driven by a motor 165 and provided with a pressure roller 160. It hangs in a bight between the roller 157 and an idle roller 190 at the entrance to the machine, and when the bight is drawn up by the machine it exposes a photo-electric cell by which the motor 165 is started to restore the bight. The end of the web rests on a table 145, Fig. 10, and is clamped resiliently on it by a series of closely-spaced leaf-springs 200 fixed to a shaft 201 which is rocked by a cam to release the web immediately before it is drawn across the machine by a series of grippers 247, 250 mounted on a carriage 216 running on tracks 47. The gripper jaws 247 are fixed to a non-rotating rod 210 on which the jaws 250 are pivoted, springs being provided to urge these jaws to the closed position, in which they grip the end of the web against the jaws 247, the edge of the table 145 being notched to clear the jaws. The rod 210 is fixed to the carriage 216, which is moved along its tracks between stops by endless cables 221 driven by an electric motor controlled by limit switches and by cam-actuated switches. Shafts 257 carried by the frame adjacent to the ends of the tracks 47 carry arms 254 arranged to depress the tails 255 of the movable gripper jaws 250 so as to open the grippers; the shafts 257 are inter-connected to move in unison, and are actuated by a cam so that the grippers open when the carriage approaches the position shown and again after it reaches its other extreme position. Before the grippers are opened in the latter position a bar 283, Fig. 1A, carried by arms on a cam-actuated shaft 285, is moved down to depress the middle portion of the web into a slot 77 between supporting tables 75, 76 so as to draw off a predetermined additional amount of web and form slack in the web. Web holding and cutting.-Also before the grippers 247, 250 are opened after drawing off a length of web as described above, holding- down plates 300, Fig. 10, carried by arms on shafts 303 which are interconnected and actuated by a cam, are lowered to hold the web against endless conveyer belts 700 (then stationary) adjacent to hem-supporting plates 130, 136, Fig. 14. An endless ribbon-like cutting blade 380, Fig. 10, with a razor-sharp upper edge, is carried by end pulleys and intermediate supporting rollers in a housing 194 (see also Fig. 1A), over which the web W passes, and is continuously driven by a motor 401. The housing 194 is fixed to a bar 381 which is supported on pivots 386 so arranged that one end of the housing is higher than the other; the bar 381 has an arm 410 adjustably connected to a rod 411 whereby it is rocked at the appropriate time by a cam to raise the inner run of the blade 380 against the web, the inclination of the housing 194 from end to end causing the cutting operation to start at one edge of the web and progress across to the other edge. First folding.-After the blank B is cut off from the web, its raw ends are folded over, to form narrow and wide hems respectively. The edge B<1> just cut is turned over the adjacent holding plate 300 by a member 441, Figs. 10 and 14, carried by arms 445 on a cam-actuated rock-shaft 446, and the edge B<2> previously cut is folded over to a greater extent by a member 460, over which it lies before it is folded; the member 460 is slidably mounted on a spacer 461 on the supporting plate 130 and is linked to upwardly-extending arms on a horizontal cam-actuated rock-shaft. Blank feeding.-After the edges of the blank have been folded over, the blank is carried sideways by the belts 700 and intermediate belts 701, Fig. 1A, of which the upper runs rest on the tables 75, 76, and by belts 706 acting as continuations of the belts 700, 701, to carry the blank past means 483 for folding in the raw edges of the hems, as described below, and sewing heads 540 for stitching the hems. The upper runs of the belts 700 are urged upwards by spring-pressed rollers adjacent the delivery ends of the holding plates 300 to give sufficient bite to start the movement of the blank. Idle presser belts 495, Fig. 21, are provided above the belts 706 with their lower runs pressed downwards by rollers on spring- urged arms 497, Fig. 7, to hold the blank against the conveyer belts. All the belts are grooved longitudinally to keep the hems parallel (see Fig. 21). The belts carrying the right-hand half of the blank are driven separately from those carrying the left-hand half in order that the sewing of the two edges may be separately regulated in case one edge lags behind the other. The belts are driven by motors 364, 580, Fig. 7, providing fast and slow drives respectively; each motor 364 drives a pulley 361, Fig. 1A, and each motor 580 a reduction gear 360, the latter drive preferably including pulleys of adjustable effective diameter. The belts 700, 701 are driven directly from the pulleys 361 by belts 712, and the shaft 350 driving the belts 706 is connected to the pulley 361 and gear 360 by clutches whereby the shaft rotates with the faster of these two driving means; the arrangement is such that while the blank is being fed clear of its initial position all the belts are driven by the motors 364, and these motors are then stopped and the motors 580 started so that the belts 700, 701 are stationary while a further length of the web is drawn across the machine and the belts 706 move slowly while the hems are stitched. Discharge belts 366 driven direct from the reduction gear 360 are provided to carry the finished sheet away from the sewing heads; in a modification, the belts 706 are extended to take the place of the belts 366. In an alternative arrangement, which does not allow a length of web to be drawn off before the sewing of the preceding blank has been finished, the two sets of belts 700-701 and 706 are combined into long belts driven at alternative speeds in the manner described above for the belts 706; these belts are stationary during the drawing-off, cutting, and first folding of the blank, move fast to carry the blank up to the sewing heads and then, after a momentary stop, move slowly during the stitching. Second folding.-While the blank B is being fed up to the sewing heads the raw edges of the folded hems are folded in by stationary guides. The hem-supporting plate 521, Fig. 21, is slotted longitudinally, and the hem edge is deflected into the slot by a downwardlyinclined plate fixed to the entrance end of the upper plate 520 and a flange 527 on the spacer between the plates 520, 521; a guide member 530 deflects the body of the blank downwards to allow the under-folding of the edge; an upwardly-inclined plate 535, Fig. 7, spaced below the plate 521 completes the folding-in. Sewing. The sewing-heads 540 are driven by the motors 580 which give the slow conveyerbelt movement; the heads themselves have no feed mechanism. The fast feed motors 364 are stopped by switches 545 actuated by feelers 544 engaged by the work, and after a brief stop the presser-feet of the sewing heads are lowered by solenoids controlled by a camactuated switch, the motors 580 are started by the same switch. The latter motors are stopped when the work moves clear of the feelers of a second pair of switches 550. Separate sets of switches are provided for the two heads to ensure that the sewing of each hem is properly started and completed; in a modification a single switch could control all four motors. Specification 464,742 and U.S.A. Specifications 1,662,654 and 2,509,443 are referred to.