Classifications

• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04B—KNITTING
  • D04B15/00—Details of, or auxiliary devices incorporated in, weft knitting machines, restricted to machines of this kind
  • D04B15/94—Driving-gear not otherwise provided for

Definitions

• This invention relates to racking mechanisms for circular knitting machines, particularly machines for the manufacture of socks and stockings.
• the invention aims to provide a racking mechanism for applying racking strokes selectively to a rackwheel which may be uniformly cut or rackwheel assembly rotatable conjointly with a control or programme drum.
• a racking mechanism for applying racking strokes selectively to a rackwheel which may be uniformly cut or rackwheel assembly rotatable conjointly with a control or programme drum.
• the invention provides a circular knitting machine having a needle cylinder, a control drum for controlling the knitting operation performed by the cylinder and a racking mechanism for incrementally advancing the control drum when required, said racking mechanism including a pair of pawls mounted on each of a pair of pawl carriers so as to engage when desired at a particular position on the periphery of a rack wheel, cam means on a shaft rotatable in a predetermined relationship to the needlecylinder rotation to move the carriers so that each pair of pawls performs an early and a late stroke in seriatim fashion during a pre determined extent of revolution of the needle cylinder, cam operated bluffing means for engaging a predetermined one of each pair of pawls to make their early stroke ineffective and selecting means mounted on the periphery of the rackwheel which one of the pawls should be effective in advancing the rackwheel for a subsequent increment.
• pawls can be made to "recognise" a particular tooth of the rackwheel and so move that tooth onward during a predetermined stage of cylinder revolution. Only two cams need to be provided to advance the pawls. An operative can instantly determine at what time the control drum is intended to be moved. A direct selection can be used.
• Figure 1 is a perspective view from one side of the rackwheel of a racking mechanism of the invention showing a pair of pawls engaged in a tooth of the rackwheel at the end of a racking stroke and a pair of pawls about to start a racking stroke;
• Figure 2 is a perspective view similar to Figure 1 but from the other side of the rackwheel;
• Figure 3 is a view similar to Figure 1, but showing the nearside pawl bluffed directly by a masking plate secured in a tooth of the rackwheel;
• Figure 4 is a view similar to Figure 2, but with the rackwheel teeth broken away to show a bluffing slide located within a central groove formed in the rackwheel.
• an evenly cut rackwheel has a central groove 2 cut midway of the width of the rackwheel teeth to a depth just below the roots of the teeth.
• a pair of pawls 3 and 4 are arranged to cooperate with teeth on one side of the groove 2 and another pair of pawls 5 and 6 are arranged to cooperate with the teeth on the other side of the groove 2.
• the pairs of pawls are pivotably mounted at 9 on pawl carriers 7 and 8, one . carrier to each pair of pawls.
• the pawls are biased towards the rackwheel 1 by resilient springs (not visible).
• the carriers 7 and 8 have cam follower rollers (not shown) through which they are reciprocated by four lobed cams of the type shown in British Patent 1,094,924 so as to provide a total of eight possible racks, four to each carrier, during every two cylinder revolutions.
• the pawls can be raised clear of the rackwheel 1 by a common rod 10 which is fixed on a pivotable arm 11 carried suitable on a pivot pin (not shown) secured to the frame of the knitting machine.
• the rod 10 projects, at one side, over the usual follower for a timing chain (not shown) so that it can be raised and lowered by the passage of chain studs in the usual manner.
• the rack selecting means or rack bluffing means, consists of four devices:- a. Direct bluffing devices for masking the teeth of the rackwheel 1 and fixed to the rackwheel. b. Movable bluffing device for acting on the inner pawls 4 and 5 nearest the groove.2, of the two pairs of pawls. c. Movable bluffing device for acting on all four pawls. d. Movable bluffing device for preventing racking by all the pawls until a subsequent timing chain stud is advanced under the chain follower, inspite of the pawls being lowered by a chain stud already under the follower. This bluffing device acts in the same manner as the collapsible nose feeler la described in British Patent 1,094,924
• the direct bluffing devices consist simply of suitably shaped blocks or masking pieces 12 which are secured by any appropriate means in a tooth space of the rackwheel 1.
• the block may be only wide enough to engage (bluff) a single pawl as shown, or it may be wide enough to span both pawls of a pair.
• the direct bluffing devices prevent all pawls except one from engaging each tooth to ensure that, each tooth is only engaged by the intended pawl. Many of the Figures do not show the direct bluffing devices for ease of representation.
• the movable bluffing device b consists of a slide 13 having an angled nose which rests in the central groove 2 in the rackwheel.
• the slide is high enough to prevent the two inner pawls 4 and 5 from engaging. the rackwheel 10 by engaging the wider noses of the inner pawls and lifting them to above the rackwheel teeth.
• the slide 13 is reciprocated forwards and backwards in its groove by cam means (not shown) in similar manner to the feelers, 1,2,3 and 4, shown in Figure 1 of British Patent 1,094,924.
• the timing of movement of the slide 13 is such that it remains forward (as shown in
• a block 12 is located under pawl 3.
• Slide 13 is forward. Pawls 3 and 4 cannot engage tooth on the first quarter revolution.
• pawls 3 and 4 are bluffed as above. No block is provided under pawl 6.
• Slide 13 is forward bluffing pawl 5, but pawl 6 can engage the rackwheel tooth.
• blocks 12 are located under pawls 3 and 6. Slide 13 is forward. Pawls 5 and 6 cannot engage tooth on the second quarter -revolution. To rack in the third quarter revolution, blocks 12 are under pawls 3 and 6. Slide 13 is moved back after half a revolution allowing pawl 4 to engage the tooth.
• blocks 12 are provided tinder pawls 3 and 6 and the slide 13 in its forward position has bluffed for half a revolution.
• the slide 13 is retracted but a bJ ock 12 under pawl 4 prevents a rack on the third quarter revolution.
• blocks 12 are provided under pawls 3, 4 and 6, but slide 13 having moved back after half a revolution, allows pawl 5 to engage the tooth.
• a further bluffing device ( Figure 1) consists of a collapsible nose or follower 19 which is pivotably and/or slidably attached by a shoulder screw 20 to a slide 21.
• the nose 19 is shown in the lowered position having been withdrawn from a peg 22.
• the nose 19 can only be raised onto a peg by movement of the rackwheel which advances a peg 22a from behind the nose.
• the slide 21 functions in an analogous way as the feeler bar 1 in British Patent 1.094,924.
• the slide 21 is advanced by an appropriate cam to the position shown in Figure 1 and remains in the advanced position, during racks 2-8 inclusive, of any 8 rack sequence of a quarter revolution each initiated by a chain stud.
• the slide 21 withdraws just prior to the first rack of any sequence, and therefore, allows rack 1 to take place. It is advanced immediately after rack 1 to be available for bluffing any remaining racks 2-8 should they not be required until a subsequent chain stud is advanced under the chain follower.
• the slide 21 repeats its reciprocatory action every two revolutions of the needle cylinder and the nose 19 merely reciprocates in the low position shown in Figure 1 after it has been removed from a peg at the end of a racking sequence. If there is no peg 22a. following immediately behind peg 22 the nose 19 may be allowed to rest on a flange 23 formed on the side of the rackwheel 1.
• the bluffing device d functions as follows. Consider that a timing chain stud has caused release of the pawls by lowering the rod 10 and that a racking sequence is in progress. It may be that, having taken one or more racks of the eight racking strokes made available by the chain stud, it is desired to cease racking before the eighth rack has taken place and before the follower has dropped off the chain stud. However, the last rack which was taken (say, for instance rack 5), would bring up a further tooth of the rackwheel which is due to be racked when the next chain stud is advanced under the chain follower.
• the bluffing device 16, shown in Figures 2 and 4 can be made to positively distinguish between first and second cylinder revolutions.
• the pegs 17 and 17a as shown are situated adjacent tooth spaces, however, if two holes are drilled adjacent to each tooth space, it is possible to place a peg either in a forward position or a rearward position relatively to a single tooth space. If the peg is in the forward position as shown in Figures 2 and 4, the. follower 16 will rest on it during the first revolution of the needle cylinders and withdraw to the low position during the second revolution.
• the follower By placing the peg in the rearward position (which would be between pegs 17 and 17a) the follower would be held high during the second revolution and lowered during the first revolution.
• the peg By placing the peg in the appropriate position, it is possible to ensure that no racking can take place on a "wrong' revolution of the needle cylinder.
• Such a safeguard is highly desirable when racking occurs to cause the needle cylinder to either go into reciprocation or out of reciprocation, but the expedient may be used at any time to ensure that the possibility of mis- -racking is minimised.
• the bluffing device 13 ( Figure 4) could be made to positively distinguish between racking in a first half revolution and a second half revolution.
• the slide 13 can be provided with suitable bluffing projections for engaging projections on the outer pawls 3 and 6.
• the retracting movement could cause bluffing projections carried by the slide 13 to mask the parts of the tooth under the outer pawls.
• forward movement of the slide would cause bluffing of the inner pawls and unbluffing of the outer pawls and reverse movement of the slide would cause bluffing of the outer pawls and unbluffing of the inner pawls.
• a further variation in the arrangement could be to mount the pairs of racking pawls in 'U' shaped channel section rings which completely surround the rackwheel.
• the rings could be oscillated to and fro on the rackwheel by. linkages coupled to the slides 7 and 8 or coupled to bell-crank levers instead of slides.
• a rackwheel can have teeth which are clearly recognisable to effect any give particular rack of No 1 up to No 8.
• the selection being effected partly by masking pieces and partly by bluffing elements, is relatively safe and the timing is likely to be less critical than with prior art arrangements.
• a timing chain can be conveniently arranged to cooperate in appropriately timed relationship with the racking mechanism.
• the pawls fulfill two purposes at the some timer firstly the pawls serve to transmit the racking force from the carrier to the rackwheel; and secondly the pawls are made to act as sensing devices to give appropriate racks only.
• the bluffing device b merely enables certain pawl to participate in sensing and its operation is thus less critical than were the bluff itself is intended to govern selection.
• the bluffing device b operates thus without interruption but the pawls themselves are instrumental in whether racking occurs in the unbluffed condition.
• the mechanism can thus be executed in a simple mechanical arrangement.

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Knitting Machines (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10512040

Family Applications (1)

Country Status (3)

Citations (7)

• 1981
  • 1981-03-12 JP JP56500853A patent/JPS57500294A/ja active Pending
  • 1981-03-12 GB GB8131279A patent/GB2083083A/en not_active Withdrawn
  • 1981-03-12 WO PCT/GB1981/000043 patent/WO1981002592A1/en active Application Filing

Patent Citations (7)

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