GB2062695A - Tambour Safety Device - Google Patents

Tambour Safety Device Download PDF

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Publication number
GB2062695A
GB2062695A GB8035280A GB8035280A GB2062695A GB 2062695 A GB2062695 A GB 2062695A GB 8035280 A GB8035280 A GB 8035280A GB 8035280 A GB8035280 A GB 8035280A GB 2062695 A GB2062695 A GB 2062695A
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GB
United Kingdom
Prior art keywords
knitting
machine
ratchet
safety device
ratchet mechanism
Prior art date
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Granted
Application number
GB8035280A
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GB2062695B (en
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Corah Ltd
Original Assignee
Corah Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Corah Ltd filed Critical Corah Ltd
Priority to GB8035280A priority Critical patent/GB2062695B/en
Publication of GB2062695A publication Critical patent/GB2062695A/en
Application granted granted Critical
Publication of GB2062695B publication Critical patent/GB2062695B/en
Expired legal-status Critical Current

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Classifications

    • DTEXTILES; PAPER
    • D04BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04BKNITTING
    • D04B35/00Details of, or auxiliary devices incorporated in, knitting machines, not otherwise provided for
    • D04B35/10Indicating, warning, or safety devices, e.g. stop motions

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

Abstract

The present invention provides a safety device for use on a knitting machine with a tambour mechanism or the like which reduces the risk of machine damage caused by too great an accumulation of yarn loops on a needle. A mechanical form of the device has a drum (18) which is indexable with the tambour drum, each indexing actuating a link lever (32) by means of a respective cam surface (20) on the drum. The lever (32) cooperates with a pawl (56) and rack wheel (42) which is rotationally indexed by the pawl (56) a set amount for each course knitted by the machine. After rotation of the rack wheel (42) through a preselected number of indexing steps the wheel (42) actuates a switch (59) or similar mechanism to stop the machine. However, each indexing of the drum (18) actuates the lever (32) which released the rack wheel to return to its initial rest position. Thus the machine is stopped only in the absence of a change in knitting instructions over a preselected number of knitted courses. <IMAGE>

Description

SPECIFICATION Tambour Safety Device The present invention is concerned generally with a powered straight bar knitting machine and in particular with such a machine commonly known as a Cotton patent machine. The invention relates particularly both to a Tambour safety device for a powered straight bar knitting machine and a powered straight bar knitting machine when fitted with such a Tambour safety device.
A Cotton patent machine is a powered straight bar multisection bearded needle machine on which full-fashioned sweaters, hosiery and underwear, for example are produced. The machine includes a single set of needles and produces a jersey structure.
It is often desired to produce a design in stitch in knitted fabric produced on a Cotton patent machine. This may be achieved by tucking, i.e. a procedure in which when a needle receives new yarn but does not cast off an old loop, the new yarn is formed into a tuck loop with which the held, old loop combines to make a tuck stitch.
However, there is a limit to the number of yarns which can be accumulated in any one stitch, the exact number of yarns depending upon how many needles are tucking, the distribution of these needles, the kind and count of yarn used, the stitch length and various other factors. As a general rule, however, it is not advisable to produce stitches containing more than four tuck loops and failure to clear the needles after four successive tuck loops causes excessive stress on the needle beards. Should this continue the knitting elements including the bearded needles become damaged resulting in a considerable downtime period whilst reneedling is carried out.
The selection as to which needles knit or tuck is effected by means of a Tambour mechanism which includes an elongated Tambour drum having a plurality of so-called strips secured to the periphery thereof each representing knit or tuck instructions for a course of knitting.
The Tambour drum is both recriprocally and rotatably mounted. In one end position of the reciprocal movement, the drum lies adjacent the bearded needles with a strip in operative engagement via presser elements with the beards of selected needles to close those needle beards and hence cause the needles to knit plain knitting.
Where there are gaps in the strip, the needle beards remain open so that, on that course of knitting, those needles form tuck loops. In the other end position of the reciprocal movement, the drum lies remote from the needles and hence the drum is rotatable, in accordance with a knitting programme, to present a further strip to the bearded needles in the following knitted course.
Should a particular strip include one or more gaps, thus producing tuck loops, and should that strip fail to be moved on after say four courses have been knitted in accordance with the instructions contained on the strip, hen one risks damaging the knitting elements in the manner set out hereinabove.
In accordance with the broadest aspect of the present invention there is provided a safety device for a powered straight bar knitting machine of the type having a tambour mechanism or the like for imparting knitting instructions to the knitting instruments for each course knitted by the machine, the safety device comprising first means for monitoring each change in knitting instructions applied to the knitting instruments; counting means for counting the number of successive courses knitted by the machine; resetting means operable in response to each change in said knitting instructions to reset said counting means; and control means actuable responsively to said counting means reaching a preselected count for stopping the machine.
In a preferred form of the invention the counting means comprises a pawl and ratchet mechanism arranged to be indexable wih each course knitted by the machine and said control means is actuable responsively to said ratchet mechanism being indexed into a preselected position.
Conveniently the resetting means is operable to release said ratchet mechanism for enabling the ratchet mechanism to return to an initial rest position.
Preferably the counting means includes a sensor for detecting movement of a carriage of said machine through a preselected position.
Advantageously the counting means includes an electronic counter.
The present invention also provides a safety device for a powered straight bar knitting machine comprising ratchet means; a cam member having a plurality of cam surfaces each of which corresponds with instructions imparted to the knitting instruments on a particular knitted course, the cam member being adapted to be indexable a preselected amount responsively to a change in the knitting instructions; pawl means for racking the ratchet means a respective racking step after each course of knitting is completed from a rest position through a preselected number of racking steps to a second position; link means having a cam follower for engaging said cam surfaces, the link means coupling the cam member with the ratchet means and being actuable in response to indexing of the cam member to allow said ratchet means to return to said rest position; and means actuable responsively to said ratchet means reaching said second position for stopping the machine.
The invention will now be described further by way of example with reference to the accompanying drawings in which: Figure 1 is a general perspective view showing part of the Cotton patent machine having a Tambour mechanism and includes a part of a Tambour safety device in accordance with the invention, and Figure 2 is a side elevational view of a Tambour safety device in accordance with the present invention.
In Figure 1 a Tambour drum is designated 10.
The drum includes eighteen peripherally mounted strips 12 each corresponding with a course of knitting.
The drum is indexable rotationally, in known manner, to cause a particular strip, selected in accordance with a knitting programme, to lie adjacent the machines bearded needles (not shown) which are disposed in rectilinear manner alongside the drum. The strip operatively engages the bearded needles by way of presser elements (not shown) the arrangement being such that tuck loops are produced in a fabric being knitted on a machine where there is a gap in the strip. All the other needles produce plain knitting.
In addition to being indexable rotationally, the Tambour drum 10 is also reciprocally mounted.
The known mechanism for achieving this is shown diagrammatically and includes a shaft 14 which is coupled to the Tambour drum by a series of linkages 1 6. In the illustrated position the drum is in an end operative position in which it operatively engages the needles. Upon rotation of the shaft 14 clockwise, the linkages move generally downwardly thus tilting the drum 10 anti-clockwise to an inoperative position at the other end of its reciprocal movement.
The illustrated safety device of the invention includes an indexable cam member in the form of a disc 1 8 having eighteen cam surfaces or peripheral notches 20 each of which corresponds with one strip on the Tambour drum 10. The disc is mounted fast to a main drive shaft 22, which is carried in a bearing support 24 of a bracket 26 which is itself secured to a frame member 28 of the knitting machine. The shaft 22 is driven from the main drive to the knitting machine is such a manner that the disc rotates by one or two notches forward and backward each time the Tambour drum is indexed. The notches are numbered 1 to 18 and where a full ungapped strip is present on the Tambour drum, a stud is inserted in the corresponding notch of the disc 18.Thus, notch 1 7 includes such a stud 30 indicating that the corresponding strip on the Tambour drum is ungapped hence allowing the machine to run continuously producing plain fabric.
A link in the form of a cranked clawker arm 32 is pivotted at 34 to a base plate 36. One limb of the clawker arm includes a roller cam follower 38 which is engageable sequentially in the notches in the disc 18.
The other limb of the clawker arm is pointed as at 40, the point being engageable between the teeth of a rack wheel 42 of a ratchet mechanism which serves to count the number of courses knitted by the machine. The pointed limb of the clawker arm is resiliently loaded into contact with the rack wheel by means of a spring 44 the respective ends of which are fixed to the clawker and base plate by posts 46, 48.
The rack wheel 42 is mounted on a spindle 50 and includes two sets of teeth, one of which, 52, engages the clawker arm and the other of which, 54, has a racking pawl 56 resiliently received therein. The wheel includes an extension piece 55 which is normally biased anti-clockwise, as viewed, by means of a return spring 58, the spring being stretched between two posts 60, 62 located respectively on the extension piece 56 and the base plate 36. In the illustrated position however anti-clockwise rotation of the rack wheel is prevented by engagement of both the point 40 of the clawker arm 32 in the set of teeth 52 and the pawl 56 in the set of teeth 54. The face end of the extention 56 has a bolt 57 adjustably secured thereto, the bolt being engageable with a microswitch 59 in a manner to be described.
The pawl 56 is pivotally mounted at 64 to a lever 66 which is itself pivotally mounted on the spindle 50. The pawl is loaded resiliently into contact with the set of teeth 54 by a spring 72 secured between a post 74 disposed intermediate the ends of the pawl and a fixed post (not shown).
The lever 66 is normally biased anti-clockwise, as viewed, by means of a spring 68 which extends between a post 70 on the lever 66 and a fixed post (not shown).
An operating rod 76 is arranged to rack the rack wheel 42 by one tooth for each course of knitting. The operating rod is vertically actuable, as viewed, by way of a cam on the main cam shaft (not shown) of the knitting machine. Thus, as the rod 76 is raised by its associated cam, the lever 66 and hence the pawl 56 are rotated clockwse thereby rotating also the rack wheel 42 against the action of the spring 58. During racking, the clawker arm 32 is raised by an amount sufficient to allow one tooth to pass beneath it. Hence, assuming that the Tambour drum is not rotated for the next course of knitting, the rack wheel is again rotated by one tooth.
Assuming that the Tambour drum is not rotated, this action continues until the bolt 57 engages and operates the microswitch 59 which disconnects the power source from the knitting machine and hence shuts it down. If however the Tambour drum rotates, the clawker arm is moved out from one notch and hence rotated slightly anti-clockwise to remove the pointed limb 40 from the set of teeth 52. At the same time, the pawl 56 is clear of the set of teeth 54, since the operating rod 76 is being lowered, thus enabling the rack wheel 42 to return to a rest position adjacent the first tooth in the tooth set 54.
In the illustrated, preferred embodiment of the invention, a bluff 78 is interposed between the pawl 56 and the rack wheel 42. The bluff serves to hold the pawl out of contact with the set of teeth 54 whilst the rack wheel 42 returns to its rest position.
A further modification is the provision of a retaining clawker bluff 80. The bluff 80 is in the form of a bell crank pivotted at its centre to the spindle 50. The left sides, as viewed, of the bluff is resiliently loaded downwardly by means of a spring so that the bluff rests against the underside of the point 40. When the point is pivotted away from the set of teeth 52 therefore a flat 86 engages behind the point 40 to prevent damage either to the point or the rack wheel whilst the rack wheel returns to its rest position.
In a still further modification a course adjustment link 88 is provided for enabling the safety device to operate after a number of knitted courses different from four. The link is pivotted at 90 and includes a slot 92 in which a bolt 94 is received. An end of the link is stepped and each step is engageable against a rear surface 96 of the rack wheel. Hence, when one step of the link 88 engages the surface 96, the safety device operates after four knitted courses when the link 88 is turned and another step engages the surface 96, the safety device operates after say three courses. In this way the safety device may be made to operate after a preset number of courses as determined by the stepped configuration of the link 88.
A stop screw 98 may be provided on the microswitch structure 59 to support the lever 66 during the lower part of a racking movement.
While the above described preferred form of safety device is a mechanical device it will be appreciated by those skilled in the art that electrical or electronic or electromechanical devices may also be used. For example, an electronic device according to the present invention comprises a counter for counting the number of courses knitted by the machine, the counter being stepped by pulses received from suitable sensors such as microswitches or proximity sensors which detect the passage of a carriage of the machine as the carriage effects knitting of a course on the machine. A trigger circuit is actuated by the counter when the latter reaches a preselected count, the trigger circuit then switching off power supply to the machine to prevent the knitting of further courses, or alternatively initiating a change in the knitting instructions. The change in knitting instructions may be sensed by means of a suitable sensor such as microswitch which is tripped, for example, by rotation of the tambour drum, to reset the counter.
In an electromechanical safety device according to the present invention various of the mechanical parts described above may be substituted by electronic circuitry. For example, the clawker arm 32 and the rack wheel 42 and associated mechanical parts may be replaced by an electronic counter such as a shift register which counts the number of knitted courses and is reset by pulses received from a microswitch which is tripped on each indexing of the disc 1 8.

Claims (14)

Claims
1. A safety device for a powered straight bar knitting machine of the type having a tambour mechanism or the like for imparting knitting instructions to the knitting instruments for each course knitted by the machine, the safety device comprising first means for monitoring each change in knitting instructions applied to the knitting instruments; counting means for counting the number of successive courses knitted by the machine; resetting means operable in response to each change in said knitting instructions to reset said counting means; and control means actuable responsively to said counting means reaching a preselected count for stopping the machine.
2. A device as claimed in claim 1 wherein said counting means comprises a pawl and ratchet mechanism arranged to be indexable with each course knitted by the machine and said control means is actuable responsively to said ratchet mechanism being indexed into a preselected position.
3. A device as claimed in claim 2 wherein said resetting means is operable to release said ratchet mechanism for enabling the ratchet mechanism to return to an initial rest position.
4. A device as claimed in claim 2 or 3 wherein said ratchet mechanism includes a rack wheel.
5. A device as claimed in claim 2 or 3 wherein said ratchet mechanism includes a rack.
6. A device as claimed in any of claims 2 to 5 wherein said first means comprises a member which is adapted to be indexable a preset amount in response to each change in the knitting instructions, and a link means coupling said member to said pawl and ratchet mechanism such that indexing of said member causes said link means to release the ratchet mechanism for enabling the ratchet mechanism to return to its initial rest position.
7. A device as claimed in claim 6 wherein said member is a rotatable member having a plurality of peripheral cam surfaces each of which corresponds with instructions imparted to the knitting instrument on a particular knitted course, a respective one of the cam surfaces being indexed into juxtaposition with a cam follower of the link means on each indexing step of the member.
8. A device as claimed in claim 1 wherein said counting means includes a sensor for detecting movement of a carriage of said machine through a preselected position.
9. A device as claimed in claim 1 or 8 wherein said counting means includes an electronic counter.
1 0. A safety device for a powered straight bar knitting machine comprising ratchet means; a cam member having a plurality of cam surfaces each of which corresponds with instructions imparted to the knitting instruments on a particular knitted course, the cam member being adapted to be indexable a preselected amount responsively to a change in the knitting instructions; a pawl means for racking the ratchet means a respective racking step after each course of knitting is completed from a rest position through a preselected number of racking steps to second position; link means having a cam follower for engaging said cam surfaces, the link means coupling the cam member with the ratchet means and being actuable in response to indexing of the cam member to allow said ratchet means to return to said rest position, and means actuable responsively to said ratchet means reaching said second position for stopping the machine.
11. A device as claimed in claim 10 wherein the ratchet means comprises a rack wheel and said link means comprises a lever engageable with a first set of teeth on the rack wheel for preventing return of the rack wheel to its rest position and wherein during indexing of said cam member the lever is disengaged from said teeth.
12. A device as claimed in claim 11 comprising a clawker bluff for preventing reengagement of the lever with the teeth during return movement of the rack wheel to its rest position.
13. A device as claimed in claim 10, 11 or 12 wherein the cam member is a rotatable member and said cam surfaces comprise peripheral notches on said member.
14. A device as claimed in any of claims 10 to 1 3 further comprising adjustment means for enabling adjustment of said preselected number of racking steps.
1 5. A safety device for a powered straight bar knitting machine the device being constructed arranged and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.
1 6. A safety device for a powered straight bar knitting machine the device being constructed arranged and adapted to operate substantially as described and shown in the specification and drawings accompanying patent application No.
7939421.
1 7. A powered straight bar knitting machine having a safety device as claimed in any of the preceding claims.
GB8035280A 1979-11-14 1980-11-03 Tambour safety device Expired GB2062695B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8035280A GB2062695B (en) 1979-11-14 1980-11-03 Tambour safety device

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB7939421 1979-11-14
GB8035280A GB2062695B (en) 1979-11-14 1980-11-03 Tambour safety device

Publications (2)

Publication Number Publication Date
GB2062695A true GB2062695A (en) 1981-05-28
GB2062695B GB2062695B (en) 1983-09-07

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101260594B (en) * 2008-04-23 2010-06-09 孙平范 Safety alarm device for flat knitting machine

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101260594B (en) * 2008-04-23 2010-06-09 孙平范 Safety alarm device for flat knitting machine

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Publication number Publication date
GB2062695B (en) 1983-09-07

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