Patent GB-598468-A (GB)
Title: Improvements in or relating to straight-bar knitting machines
IPC: D04B11/32
Filed: 1944-07-06
Abstract: 598,468. Knitting-machines. DEHN; F. B. (Textile Machine Works)..July 6, 1944, No. 12929. [Class 74 (ii)] In knitting a turned welt upon a straight-bar machine, the welt hooks are moved to a position between the needles to receive the alternate loops of the first course, are moved away from the needles as knitting proceeds, are moved towards the needles to a position in front of the needles and remain in that position while knitting proceeds, and finally are moved to a position in between the needles for the loops to be restored to the needles. The welt wires are placed manually upon the fabric before the hooks are moved towards the needles to their intermediate position, and draw-off straps having hooks thereon are moved towards the needles to a position between the wires and the needles, are held in this position temporarily, and are then rapidly withdrawn to engage the wires to apply tension to the wires and fabric. Tension is applied to the fabric both by means of a weight and by spring means, each of which devices can apply torque to a common shaft, and a clutch is provided between the weight and the shaft so that the spring can act upon the shaft without affecting the weight. A group of five cams is provided for operating the knock-over bits, and selecting means comprising a disc having projecting pins of different length to engage levers arranged in different planes are provided for determining which cam controls the movement of the knock-over bits. Means are provided for giving the needle bar an additional forward movement during the return of the loops from the welt hooks to the needles. The welt hooks project from one side of a welt bar having at its other side resilient members arranged to receive the thrust in moving the bar towards the needles. A welt hook is provided between each pair of needles, and a member is mounted upon the welt bar between each second pair of welt hooks to position the loops upon the welt hooks for return to the needles. The welt bars 354 with the welt hooks 351 thereon are moved towards the needles 26 by pins 381 carried upon links 382 pivoted to levers 384. The levers 384 are mounted upon a shaft 385 which is oscillated by racks 387, Fig. 27, and pinions 388 upon the shaft 385. The racks 387 are pivoted to links 389, in turn pivoted to levers 392 carrying cam followers 394. Each follower 394 can be moved axially by pattern mechanism to engage either a circular disc 398 or one of three cams 399, 401, 402. Each of the cams 401, 402 moves the welt hooks to a position between the needles, the cam 402 maintaining the hooks in this position for a longer period than the cam 401 to facilitate the return of the loops to the needles. The cam 399 moves the welt hooks to the intermediate position in front of the needles, and to maintain the hooks in this position while the fabric is drawn off by the welt wire, a locking lever 408 is mounted upon the lever 392 and engages the upper surface of a bracket 437 to hold the lever 392 in the position to which it has been raised by the cam 399. When the lever 392 is raised yet further by the cam 402, a second lever 404 mounted upon the lever 392 is rotated by engagement with a lever 417 to swing the locking lever 408 away from the bracket 437. The pins 381 engage resilient projections 357 on the welt bars and the cams 399, 401, 402 serve only to move the welt hooks towards the needles. Weight-operated means are provided for applying tension to the fabric through the welt hooks, and both weight-operated and spring- operated means can apply tension to the fabric through the welt wires. Straps 677, Fig. 43, are secured to loops 358 upon the welt bars and to pulleys 679 upon a shaft 681 which has at its end a pulley around which is wrapped a cable carrying a weight. Straps 691 having hooks 692 to embrace the welt wires 676 are secured to drums 693 fixed upon a shaft 694. A pulley 695, Fig. 70, is loosely mounted upon the shaft 694 and has wrapped about it a cable 696 carrying a second weight. The pulley 695 also carries a pawl 705 which engages a notch in a collar 701 upon the shaft 694 to drive the shaft to apply tension to the straps 691. The shaft 694 can also be driven by a pawl 718 engaging a ratchet wheel 763 upon the shaft, the pawl 718 being moved away from the teeth of the ratchet wheel by a cam and with driving engagement with the teeth by springs. The spring-actuated pawl is brought into operation when a pin 708 upon the pulley 695 engages a lever 742 to raise a stop 735 to release a control rod 175 which actuates a bell-crank lever 728 and link 722 to move a mask 719 from beneath the pawl 718. A handle 714 is provided for rotating the shaft 694 to wind up the weight, a claw coupling 715, 716 being provided so that the handle can be free of the shaft. A group of five cams 285, Fig. 94, is provided for actuating the knock-over bits 73 so that their movements may be different when yarn is being laid for the first course of the welt or during idling courses, when the first, say, eighteen courses of the welt are being knitted, when the following courses of the welt are being knitted, during the knitting of the last course of the welt, and subsequently when knitting with a reinforcing thread. The cams 285 act upon a follower 293 carried upon a lever 290 which acts through links 291, 287, 279 and lever 288 to operate the knock-over bits. For moving the follower 293 axially of the camshaft 42 to bring it into register with the various cams 285, a forked lever 295 is mounted upon an axially movable rod 296, which is controlled by patterning mechanism. The patterning mechanism comprises a disc 326, Fig. 104, mounted upon a shaft 317 rotated intermittently by pawl-and-ratchet means under control of a timing chain, the disc having pins 327 ... 331 of different length fixed in holes 332 therein. Some of the pins are of uniform diameter throughout their length, and others have the free ends reduced in diameter. Levers 334 ... 337 are provided for engaging the pins 327 ... 331, and the raising of one of the levers operates the forked lever 295 to move the follower 293 into register with a corresponding cam 285. The needle bar 27, Fig. 82, can be tilted forwardly, to facilitate transfer of loops from the welt hooks to the needles, by a cam 571 and lever 558. In sections of the machine employing presser cams for giving the horizontal movement to the needle bars, each of the links 46 are normally connected to a lever 37 carrying a presser cam follower 41 by a socket 54 embracing a pin 49 upon the lever 37. The needle bar 27 is tilted forwardly by moving the link 46 with respect to the lever 37, a pin 533 upon the link engaging in a slot 532 of a metal loop 531 pivoted upon the pin 49. A pin 536 upon the loop 531 is engaged by a notch 535, Fig. 81 (not shown), in the arm 534 of a bellcrank lever 537 actuated by the cam 571 and lever 558. The bell-crank lever 537 is mounted upon a lever 539 secured to a shaft 549 axially movable under pattern control, and in the normal position of the shaft 549, a projection 564 on the lever 539 is engaged by an arm 562 upon the lever 558 so that the levers 558, 539 are locked together so that the shaft 549 is not rotated and the arm 534 is raised so that the notch 535 is freed from the pin 536. Upon axial movement of the shaft 549, the projections 562, 564 are moved out of register, and the shaft 549 is rotated to move the arm 534, rotating the loop 531 and moving the link 46. The welt hooks 351, Fig. 15, extend substantially horizontally from the welt bars 354 and transfer instruments 359, one to each pair of welt hooks are obliquely disposed so as to project slightly above the welt hooks to position the loops upon the hooks for transfer to the needles. The transfer instruments may have grooves in the ends 371, Fig. 23, thereof, to receive the needles 26, and alternate welt hooks 368 may be bent downwardly slightly where the transfer instruments cross them to facilitate the passage of the needles upwardly through the loops held by the hooks. Resilient members 356 may be secured to the welt bars to receive the thrust of the pins 381. Specification 598,526 is referred to.