Weaving machine with cam disc for homogenising warp tension

Abstract

 The present invention relates to heald frames movement using a modified cam mechanism in weaving machines. The modified cam mechanism having at least two protrusions for lifting the heald frames such that shed formed between plurality of warp yarns for passage of the weft carrier on a weaving loom remains in lower to middle region of the shed during beating up operation. During beating up operation at pre-determined angle of the modified cam, the warp yarns are loaded equally and oscillating backrest is synchronized to take up difference in length of warp yarns as the heald frame moves irrespective of the weave. Further, the present invention relates to an improvement in the weave ability of yarns with near zero elasticity at high speeds without creating high peak tensions.

Description

FIELD OF INVENTION

[0001] The present invention relates to an improvement in heald frame movement in weaving machines to improve the weave ability. More particularly, the present invention relates to a heald frame movement using a modified cam mechanism. Further, the present invention relates to an improvement in the weave ability of yarns with near zero elasticity at high speeds without creating high peak tensions.

DESCRIPTION OF PRIOR ART

[0002] Warp and filling yarns interlace with each other at right angles to form a weave. Weaving is done using a loom to interlace two sets of yarns to each other. Conventional loom uses weft yarns carried on a pirn in a shuttle that passes through the shed. The shuttle is propelled by moving it from side to side with the help of a picking stick. This picking mechanism is power controlled by cams. On existing rapier type weaving machines, the weft is propelled by means of rapiers that pick up the filling yarn and carries it across the weaving machine. On projectile weaving machines, also referred to as gripper shuttle weaving machines, the weft is attached to a projectile/ gripper shuttle, which is propelled across the weaving width. In the case of air-jet weaving machines, compressed air is used to insert the pick. Similarly, on water-jet weaving machine water under pressure is used to insert the weft across the weaving width.

[0003] The weaving machine is warped by passing the warp yarns through heddles on two or more harnesses. When the warp yarn is moved up and down by the harness a space called shed is created through which the pick will pass. The harness can be controlled by mechanical or electronic cams. The raising and lowering sequence of warp yarns in various sequence gives rise to weave structures like twill, satin, sateen, plain weave, pile fabrics etc.

[0004] With plain weave, also referred to as 1 up 1 down weave the odd warp yarns remain on the upper shed layer, while the even warp yarns remain in the lower layer in one pick. In the next pick the warp yarns cross over. i.e., the odds yarns move down and the even yarns move up. Since the entire warp yarns are moving simultaneously, all the yarns have same tension at any given moment. Besides, the oscillating back rest assists in maintaining the tension. However, with weaves other than plain weave, it is usual practice to move only those yarns that required to be moved from top to bottom or bottom to top.

[0005] For example, with 1 up, 4 down Sateen weave where the warp yarn is split into five, the first warp yarn remains one at the upper shed and the next 4 warp yarns remain at the lower shed, at the time of pick insertion. In the next pick, the second warp yarn from below moves up and the first warp yarn above moves down and the other three warp yarn remains below during the next pick insertion,. Similarly, in the insertion next of pick, the third warp yarn moves up, the second warp yarn moves down and other three warp yarn remains below. In the insertion of fourth pick the fourth warp yarn moves up and the third warp yarn moves down. In the fifth pick the fifth warp yarn moves up and the fourth warp yarn moves down. This process is repeated for every five picks. The opposite process happens in four up and one down weaves. The same holds good for all weaves with more than 1x1 repeat.

[0006] Beating up takes place after the shedding. During, beating up the yarn that is in the lower shed and the yarn that is in the upper shed are fully stretched while the yarn that is moving from bottom to top and top to bottom will be only partially stretched. This causes a higher force on the fully stretched yarns and a moderate stress on the less stretched yarns. On existing machines, the oscillating backrest cannot be used to compensate for the extra length of the open shed yarns for weaves other than plain weave, as the length of the yarns moving will be different except at the fully opened stage. Hence, during beat up different yarns will have different length and tension.

[0007] US6135163 provides a warp thread tension compensation for the different thread groups during shedding with the help of a various tensioning module is attached at the circumference of the back rest.

[0008] GB290382 discloses a method of manufacturing of leno cloth by sufficient lifting of heald frames with the help of cam modification.

[0009] GB1063688 relates to a shuttle looms which permits an increase in the height of the shuttle to the same height as that of the reed with the help of cam modification.

[0010] GB1077296 relates to a selective raising, lowering and keeping in pause or dwell condition of the heald shedding bars, according to the weaving and pattern requirement.

[0011] Indian patent application no. 14/KOL/2008 discloses a cam mechanism for the shed formation and decoupling the cams from the rollers.

[0012] Thus it can be seen that needs exist to modify the cam design, which ensures an improved heald frames movement to maintain equal or near equal yarn length at all times irrespective of cam angles. Moreover, in these respects, the present invention substantially departs from the conventional concepts and designs of the prior art and in so doing it overcome other problems encountered in conventional products.

OBJECTS OF INVENTION

[0013] It is, therefore, an object of the present invention to provide an improvement in heald frame movement in weaving machines, which overcomes the above-noted disadvantages.

[0014] Accordingly, it is the primary object of the present invention to provide an improvement in heald frame movement in weaving machines to improve the weave ability.

[0015] It is another object of the present invention to provide such improvement in heald frame movement using a modified cam mechanism.

[0016] It is another object of the present invention, wherein the modified cam mechanism having at least two protrusions for lifting the heald frames such that shed formed between plurality of warp yarns for passage of the weft carrier on a weaving loom remains in lower to middle region of the shed during beating up operation.

[0017] It is another object of the present invention, wherein the protrusions are at 270 degree and 0 or 360 degree, for the production of 1 up x 3 down weave.

[0018] It is another object of the present invention to provide an improvement in the weave ability of yarns with near zero elasticity at very high speeds without creating high peak tensions.

[0019] It is another object of the present invention to provide an improvement in the weave ability of twill, drill, sateen and other such weaves with either normal or stripe or reverse or broken in any type of weaving machine.

[0020] It is another object of the present invention, wherein the modified cam mechanism aids in the movement of heald frame irrespective of the weave.

[0021] It is another object of the present invention, wherein the modification of cam mechanism correlates with the working of electronic tappet and dobby in the weaving machines.

[0022] It is another object of the present invention to provide an improvement in heald frame movement to maintain equal or near equal yarn length between dropper and fell of the cloth at all times irrespective of cam angles.

[0023] It is another object of the present invention, wherein the modified cam mechanism facilitates weaving with more than 1 x 1 repeat.

[0024] It is another object of the present invention, wherein the modified cam mechanism can be used in negative and positive driven cams.

[0025] It is another object of the present invention, wherein the modified cam mechanism can be used as a modification in electronic tappets.

SUMMARY OF INVENTION

[0026] Thus according to the basic aspect of the present invention there is provided a weaving machine having plurality of heald frames, cam mechanism, an oscillating backrest, and weft carrier, wherein the improvement comprises of:

modified cam mechanism having at least two protrusions for providing heald frames movement.

[0027] It is another aspect of the present invention, wherein the modified cam mechanism with the protrusions lifts the heald frames such that shed formed between plurality of warp yarns for passage of the weft carrier on a weaving loom remains in lower to middle region of the shed during beating up operation.

[0028] It is further aspect of the present invention, wherein during beating up operation at pre-determined angle of the modified cam, the warp yarns are loaded equally and the oscillating backrest is synchronized to take up difference in length of warp yarns as the heald frame moves irrespective of the weave.

[0029] It is yet another aspect of the present invention, wherein the protrusions are at 270 degree and 0 or 360 degree, for the production of 1 up x 3 down weave.

[0030] Another aspect of the present invention is directed to provide heald frames movement using modified cam mechanism in the weaving machine comprising:

moving the plurality of warp yarns held in the plurality of heald frames driven by the modified cam mechanism on the weaving loom; and

forming the shed for passage of the weft carrier between the plurality of warp yarns on the weaving loom,
wherein the modified cam mechanism with the protrusions lifts the heald frames such that the shed formed remains in lower to middle region of the shed during beating up operation,
wherein during every shedding operation, the plurality of warp yarns held in the heald frames are brought with or without a delay substantially to the shed crossing level, wherein during beating up operation at pre-determined angle of the modified cam, the warp yarns are loaded equally and the oscillating backrest is synchronized to take up difference in length of the warp yarns as the heald frames move irrespective of the weave, and
wherein after beating up operation, the lifted heald frame is lowered down to the bottom position of the shed for the insertion of next pick.

[0031] It is another aspect of the present invention, wherein the warp yarns will be at equal or near equal length between dropper and fell of cloth in the heald frames irrespective of the modified cam angles.

[0032] It is another aspect of the present invention, the heald frames movement provides weave ability of warp yarns with near zero elasticity at high speeds without creating high peak tensions.

[0033] It is another aspect of the present invention, wherein the mechanism of the modified cam is used in negative and positive driven cams.

[0034] It is another aspect of the present invention, wherein the modified cam mechanism is used as a modification in electronic tappets.

[0035] It is another aspect of the present invention, wherein the modification of cam mechanism correlates with the working of electronic tappet and dobby in the weaving machines.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGRURES

[0036] 

Figure 1: Illustrates an existing 1up x 3down cam arrangement.

Figure 2: Illustrates 1up x 3down modified cam arrangement according to the present invention.

Figure 3: Graphical representation of the movement of the heald frame using existing and modified cam arrangement.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING FIGURES

[0037] As already described, the present invention is directed towards an improvement in heald frame movement in weaving machines to improve the weave ability. This is achieved with the help of a modified cam mechanism. The modification of the cam mechanism helps to achieve the improvement in weave ability and correlates with the working of electronic tappet and dobby in weaving machines. The same principle is used in negative cams, positive driven cams and is used as a modification in electronic tappets. The improvement in heald frame movement helps to provide improvement in the weave ability of yarns with near zero elasticity at very high speeds without creating high peak tensions. Additionally, the present invention also helps to provide an improvement in the weave ability of twill, drill, sateen and other such weaves with either normal or stripe or reverse or broken in any type of weaving machine and facilitates weaving with more than 1x1 repeat.

[0038] Referring to Figure 1, a conventional design of 1 up x 3 down cam arrangement is shown. In weaving process using conventional cam, beating will result in yarns having different length and tension. Figure 2 illustrates 1 up x 3 down modified cam arrangement according to the present invention. The figure illustrates modifications to the cam mechanism at change points between picks. The modified cam mechanism has at least two protrusions for lifting plurality of heald frames such that shed remains in the lower to middle region during beating up operation. At the positions of protrusions that is when the protrusions are at 270 degree and 0 or 360 degree the cam lifts the heald frames carrying warp yarns that should remain in the lower shed up to the middle of the shed and lower them again to the bottom such that the movement of the heald frames is smooth and does not interfere with weft insertion. Figure 3 is a graphical representation of the movement of the heald frame using existing and modified cam mechanism of the present invention.

[0039] The improved heald frame movement is achieved by the shuttle less cam looms or weaving machine comprising the modified cam mechanism, and the heald frame for movement of plurality of warp yarns. This forms the shed for the passage of shuttle or weft carrier between plurality of warp yarn on a weaving loom. After shedding, in next pick insertion, plurality of warp yarns are brought with or without delay substantially to the shed crossing level, and then brought back to the starting position. Thus, there will be equal or near equal length of said yarns between the dropper and fell of the cloth in all the heald frames driven by the modified cams at all times irrespective of cam angles. In weaves where the warp yarn is split into five, the warp yarn remains 1 up, 4 down at the time of pick insertion as in the case of 1 up, 4 down Sateen weave, the first warp is brought up while warps 2, 3, 4 and 5 remains below during pick insertion. After shedding, in the next pick insertion, first warp is brought down and the second warp brought up. During every shedding operation, the protrusions in the modified cam lift the plurality of heald frames carrying plurality of warp yarns such that the shed remain in the lower to the middle region during beat up and after the beat up, the lifted heald frames are lowered down to the bottom position of the shed for the insertion of next pick. Therefore, Warp 3, 4 and 5 is brought up with or without a delay up to the shed crossing level (just below) and then brought back to the starting position (below) position. During this process, the warp yarns will be at equal or near equal length between dropper and fell of cloth in the heald frames irrespective of the modified cam angles.

[0040] During beating up at pre-determined angle, the warp yarns are loaded equally and the oscillating backrest is synchronized to take up the extra length of the warp yarns. Having identical tension in all the warp yarns or near identical tension on all warp yarns during beat up helps oscillating backrest to take up the difference in length of yarn as the heald frame moves irrespective of the weave. The modified cam mechanism aids in the movement of heald frame irrespective of the weave. The movement can be modified to suit the speed of weaving thus reducing the acceleration, deceleration that happens during very high speed weaving as the heald frame can move up to 75 % and return back without moving to the neutral position.

[0041] By keeping the length of yarn from warp stop motion to the fell of the cloth equal or near equal in all heald frames irrespective of the modified cam angles helps weave yarns with very low elasticity. The modified cam mechanism improves the weave ability and allows weaving near zero elasticity yarns at very high speeds without creating high peak tensions. The reduction in tension on the warp yarn is lower if the heald frames remains at the bottom during the beat up. The same holds good for all weaves with more than 1x1 repeat.

Claims

1. A weaving machine having plurality of heald frames, cam mechanism, an oscillating backrest, and weft carrier, wherein the improvement comprises of:

modified cam mechanism having at least two protrusions for providing heald frames movement.

2. The weaving machine as claimed in claim 1, wherein the modified cam mechanism with the protrusions lifts the heald frames such that shed formed between plurality of warp yarns for passage of the weft carrier on a weaving loom remains in lower to middle region of the shed during beating up operation.

3. The weaving machine as claimed in claim 2, wherein during beating up operation at pre-determined angle of the modified cam, the warp yarns are loaded equally and the oscillating backrest is synchronized to take up difference in length of warp yarns as the heald frame moves irrespective of the weave.

4. The weaving machine as claimed in claims 1 and 2, wherein the protrusions are at 270 degree and 0 or 360 degree, for the production of 1 up x 3 down weave.

5. Heald frames movement using modified cam mechanism in the weaving machine as claimed in anyone of claims 1 to 4 comprising:

moving the plurality of warp yarns held in the plurality of heald frames driven by the modified cam mechanism on the weaving loom; and

forming the shed for passage of the weft carrier between the plurality of warp yarns on the weaving loom,
wherein the modified cam mechanism with the protrusions lifts the heald frames such that the shed formed remains in lower to middle region of the shed during beating up operation,
wherein during every shedding operation, the plurality of warp yarns held in the heald frames are brought with or without a delay substantially to the shed crossing level,
wherein during beating up operation at pre-determined angle of the modified cam, the warp yarns are loaded equally and the oscillating backrest is synchronized to take up difference in length of the warp yarns as the heald frames move irrespective of the weave, and
wherein after beating up operation, the lifted heald frame is lowered down to the bottom position of the shed for the insertion of next pick.

6. The heald frame movement as claimed in claim 5, wherein the warp yarns will be at equal or near equal length between dropper and fell of cloth in the heald frames irrespective of the modified cam angles.

7. The heald frame movement as claimed in claim 5 provides weave ability of warp yarns with near zero elasticity at high speeds without creating high peak tensions.

8. The heald frame movement as claimed claim 5, wherein the mechanism of the modified cam is used in negative and positive driven cams.

9. The heald frame movement as claimed in claim 5, wherein the modified cam mechanism is used as a modification in electronic tappets.

10. The heald frame movement as claimed in claim 9, wherein the modification of cam mechanism correlates with the working of electronic tappet and dobby in the weaving machines.

Drawing