GB2545324A - Improvements in or relating to weaving looms - Google Patents

Improvements in or relating to weaving looms Download PDF

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Publication number
GB2545324A
GB2545324A GB1618563.9A GB201618563A GB2545324A GB 2545324 A GB2545324 A GB 2545324A GB 201618563 A GB201618563 A GB 201618563A GB 2545324 A GB2545324 A GB 2545324A
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GB
United Kingdom
Prior art keywords
weft yarn
valve arrangement
control
propelling
fluid
Prior art date
Legal status (The legal status 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 status listed.)
Granted
Application number
GB1618563.9A
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GB2545324B (en
Inventor
Urquhart Clarke Christopher
John Turnbull Philip
John Watson David
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Griffith Textile Machines Ltd
Original Assignee
Griffith Textile Machines Ltd
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Filing date
Publication date
Application filed by Griffith Textile Machines Ltd filed Critical Griffith Textile Machines Ltd
Publication of GB2545324A publication Critical patent/GB2545324A/en
Application granted granted Critical
Publication of GB2545324B publication Critical patent/GB2545324B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D47/00—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms
    • D03D47/12—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein single picks of weft thread are inserted, i.e. with shedding between each pick
    • D03D47/24—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein single picks of weft thread are inserted, i.e. with shedding between each pick by gripper or dummy shuttle
    • D03D47/25—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein single picks of weft thread are inserted, i.e. with shedding between each pick by gripper or dummy shuttle inserted from only one side of loom
    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D47/00—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms
    • D03D47/28—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed
    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D47/00—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms
    • D03D47/28—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed
    • D03D47/30—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed by gas jet
    • D03D47/3006—Construction of the nozzles
    • D03D47/3013—Main nozzles
    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D47/00—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms
    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D47/00—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms
    • D03D47/28—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed
    • D03D47/30—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed by gas jet
    • D03D47/3026—Air supply systems
    • D03D47/3033—Controlling the air supply
    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D47/00—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms
    • D03D47/28—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed
    • D03D47/30—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed by gas jet
    • D03D47/3066—Control or handling of the weft at or after arrival
    • D03D47/308—Stretching or holding the weft
    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D47/00—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms
    • D03D47/34—Handling the weft between bulk storage and weft-inserting means
    • D03D47/347—Yarn brakes
    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D49/00—Details or constructional features not specially adapted for looms of a particular type
    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D49/00—Details or constructional features not specially adapted for looms of a particular type
    • D03D49/24—Mechanisms for inserting shuttle in shed
    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D49/00—Details or constructional features not specially adapted for looms of a particular type
    • D03D49/24—Mechanisms for inserting shuttle in shed
    • D03D49/42—Mechanisms for inserting shuttle in shed whereby the shuttle is propelled by liquid or gas pressure
    • D—TEXTILES; PAPER
    • D03—WEAVING
    • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
    • D03D51/00—Driving, starting, or stopping arrangements; Automatic stop motions
    • D03D51/18—Automatic stop motions
    • D03D51/34—Weft stop motions

Abstract

A weft yarn tension control mechanism 10, for use with a textile weaving loom deploying a cycle of projectiles 16 gripping the weft yarn 14. The mechanism comprises a projectile propelling mechanism (figure 2a, 12) for a first direction D1 to direct the weft yarn through a shed formed by a plurality of warp yarns. The mechanism also includes a valve 18 which includes a fluid source 20, which can be air, and which is moveable between a first position where the valve directs a propelling fluid (figure 2a, 22) towards the weft yarn to assist in the propelling of the projectile and a second position where the valve directs a tensioning fluid (figure 2b, 24) towards the weft yarn in a second direction D2 so as to tension the yarn and reduce overrun. The valve may also alter the fluid flow rate. The control mechanism may also include a brake and computer controlled units for both the brake and the valve.

Description

IMPROVEMENTS IN OR RELATING TO WEAVING LOOMS
This invention relates to a weft yarn control mechanism for use with a weaving loom deploying a cycle of projectiles gripping a weft yarn, a weaving loom including such a mechanism, and to a method of controlling a weft yarn.
It is known to make a woven fabric, such as a carpet, from weft and warp yarns. A woven fabric made from weft and warp yarns can be misshapen due to slack in the weft yarns during weaving of the yarns to produce the fabric. It is therefore important to remove slack from the weft yarns during weaving so as to prevent such misshapen fabrics being produced. This is particularly important when weaving patterned fabrics, such as patterned carpets, since even a small amount of slack in the weft yarn could result in an obvious misshapen pattern which is unpleasing to the eye.
Accordingly, there is a need for improvements to conventional weaving techniques to reduce the risk of the resultant woven fabric being misshapen.
According to a first aspect of the invention there is provided a weft yarn control mechanism, for use with a weaving loom deploying a cycle of projectiles gripping a weft yarn, comprising: a propelling mechanism configured to propel a projectile gripping the weft yarn in a first direction through a shed formed by a plurality of warp yarns; and a valve arrangement including a fluid source, the valve arrangement being moveable between a first position and a second position, wherein in the first position the valve arrangement is configured to direct a propelling fluid towards the weft yarn to apply a force to the weft yarn in the first direction so as to assist in the propelling of the projectile, and wherein in the second position the valve arrangement is configured to direct a tensioning fluid towards the weft yarn to apply a force to the weft yarn in a second direction opposite to the first direction so as to tension the weft yarn and reduce overrun of the weft yarn.
Use of a cycle of projectiles in a weaving loom, known in the art as a projectile weaving loom, provides a faster weaving time and tighter weave of weft and warp yarns than other types of weaving looms. Such a weaving loom is typically used for weaving denim fabric in which a misshapen fabric due to slack in the weft yarn is not problematic due to the movement of the denim when worn. Moreover, a projectile weaving loom is conventionally made to handle one type of weft yarn or a range of weft yarn types with similar physical properties (i.e. weight, thickness). The types of weft yarns that a conventional projectile weaving loom is typically made to handle are light, fine weft yarns with uniform properties along its length, such as a polypropylene weft yarn.
If, however, a projectile weaving loom is to be used for the manufacture of fabrics where uniformity in the resultant fabric is critical, such as is the case for carpets -especially patterned carpets, then it is important that the projectile weaving loom is able to effectively remove slack from the weft yarn during the weaving process. Moreover, when a projectile weaving loom is to be used for the manufacture of thick fabrics, such as carpets, a thick, heavy and organic (i.e. non-uniform along its length) yarn must be used, such as a jute weft yarn. In addition, oftentimes a fabric such as a carpet includes both a fine (e.g. polypropylene) weft yarn and a thick (e.g. jute) weft yarn in the same fabric piece.
Turning to the present invention, the valve arrangement being configured to direct a propelling fluid towards the weft yarn to apply a force to the weft yarn in the first direction assists in the propelling of the projectile since the propelling fluid pushes the weft yarn through the air in the first direction (i.e. the direction of travel of the projectile). Such assisting means that a lower force is required to propel the weft yarn through the shed which creates a quicker and more repeatable weft insertion.
The valve arrangement also being configured to direct a tensioning fluid towards the weft yarn to apply a force to the weft yarn in the second direction to tension the weft yarn removes any slack from along the length of the weft yarn that has travelled through the shed, and therefore reduces the risk of the resulting woven fabric being misshapen.
Moreover, directing the tensioning fluid in this manner to reduce overrun of the weft yarn further reduces the risk of the resulting woven fabric being misshapen. It will be understood that overrun is the amount of extra weft yarn that has travelled through the shed, often leaving a loop of weft yarn which is not required and can cause slack in the weft yarn. The use of a tensioning fluid to achieve a reduction in overrun means that all or at least a large amount of overrun of the weft yarn will be tensioned by the fluid, thus a greater tolerance of overrun can be handled by the weft yarn control mechanism.
In addition to the foregoing, the use of the tensioning fluid can replace a mechanical lever which is conventionally used to remove slack from a weft yarn in a weaving loom (particularly a projectile weaving loom). Such a conventional lever would grip and pull the weft yarn after it has travelled through the shed of warp yarns so as to tension the weft yarn. In such a mechanism, the amount of slack that can be removed from the weft yarn is limited to the degree of movement of the lever, e.g. typically 100mm of weft yarn overrun. Therefore, if there is a large amount of slack in the weft yarn the lever mechanism may not be able to remove all of the slack, thus resulting in the weft yarn not being fully tensioned. Moreover, once the lever brakes there may be some lateral movement of the lever in the opposite direction to that of the pull of the lever (i.e. the lever “bounces”), and as such a portion of tension may be lost.
In contrast, the present invention provides essentially a limitless amount of weft yarn overrun reduction since it is not bound by a physical lever.
Also, when changing from one weft yarn type to another (e.g. from a polypropylene yarn to a jute yarn) the conventional mechanical lever would need to be physically altered so as to allow for a different tolerance of overrun to suit that type of weft yarn. This alteration could take hours and is usually carried out by a skilled operative.
In the present invention, however, the valve arrangement provides a greater tolerance of weft yarn overrun reduction without having to change the characteristics of the valve arrangement.
In addition to the foregoing, because the conventional mechanical lever pulls the weft yarn taught, the projectile would need to have a gripper which has been selected for that particular type of weft yarn so that the projectile does not lose grip of the weft yarn when it is being pulled. When changing from one weft yarn type to another, the gripper would often need to be changed so as to suit that type of weft yarn.
In the present invention, the use of the tensioning fluid obviates the need for the grippers of the projectile to be changed when changing between weft yarn types since there is not the same mechanical strain being put onto the weft yarn. This, together with there no longer being a need to physically alter a mechanical lever, greatly reduces the set-up time of a weaving loom particularly when changing between weft yarn types. For example, when changing from a polypropylene weft yarn to a jute weft yarn the set-up time would typically be a matter of hours for a conventional weaving loom. However, the set-up time is reduced to a matter of seconds for a weaving loom using the weft yarn control mechanism of the present invention.
In addition to the foregoing, the valve arrangement provides greater control of the overall speed of a weaving loom using the weft yarn control mechanism of the invention since both the speed of the weft yarn entering the shed and the speed of removing the tension can be controlled to either slow the weaving loom down or speed it up. In this regard, it might be advantageous to slow the weaving loom down when the fabric includes a plurality of colours which requires parts of the loom to run at different speeds. Meanwhile, it might be advantageous to speed up the weaving loom to increase productivity of the fabric.
Preferably the valve arrangement is configured to switch from the first position to the second position after a predetermined time within each cycle of the projectiles in the weaving loom.
Such an arrangement means that the valve arrangement switches automatically to provide the propelling and tensioning fluid each time a projectile travels through the shed of warp yarns.
The valve arrangement in the first position may be configured to direct the propelling fluid in the first direction. Moreover, the valve arrangement in the second position may be configured to direct the tensioning fluid in the second direction.
Directing the propelling/tensioning fluid in the first/second direction provides the required force to the weft yarn in the desired direction in an efficient manner.
In some embodiments of the invention the valve arrangement may be configured to alter the flow rate of any fluid directed therefrom.
Such alteration provides a degree of control of the force being applied to the weft yarn in the first and/or second directions, and so the weft yarn control mechanism can be adapted to suit different weft yarn types. For example, a heavier, thicker yarn such a jute may need a higher flow rate than a finer yarn such a polypropylene.
Optionally the weft yarn control mechanism further includes a valve control unit configured to operate the valve arrangement in accordance with a control program.
Such an arrangement means that the valve arrangement can be set up prior to the weaving process with a bespoke control program to suit that particular fabric piece. Moreover, it means that the valve arrangement is automatically controlled during the weaving process.
The valve control unit may be configured to control the amount of time the valve arrangement is operating in the first and/or second positions. Moreover, the valve control unit may be configured to control the flow rate of the fluid being directed from the valve arrangement.
The provision of such a valve control unit provides a means for automatic control of particular characteristics of the valve arrangement. Moreover, the amount of time and/or the flow rate can be changed to suit a particular weft yarn, thus eliminating the need for physical parts (e.g. the grippers of the projectile) to be altered when changing weft yarn types.
Preferably the weft yarn control mechanism includes a brake mechanism configured to stop the weft yarn from traveling in the first direction when the brake mechanism is applied, wherein the valve arrangement is configured to remain in the second position while the brake mechanism is applied.
The inclusion of a braking mechanism permits a predetermined length of weft yarn to be propelled through the shed in the first direction before it is stopped by the brake mechanism. Meanwhile, the valve arrangement being configured to remain in the second position while the brake mechanism is applied means that the timing of the brake mechanism can be controlled so as to control the valve arrangement.
Optionally the weft yarn control mechanism further includes a brake control unit configured to operate the brake mechanism in accordance with a control program.
Such an arrangement means that the brake mechanism can be set up prior to the weaving process with a bespoke control program to suit that particular fabric piece. Moreover, it means that the brake mechanism is automatically controlled during the weaving process.
The brake control unit may be configured to control the amount of time the brake mechanism is applied.
Since the valve arrangement is configured to remain in the second position while the brake mechanism is applied, one control program can be used to control both the the brake mechanism and the valve arrangement.
The tensioning fluid and/or the propelling fluid may be or include air.
According to a second aspect of the invention there is provided a weaving loom comprising a weft yarn control mechanism as described hereinabove.
The weaving loom shares the benefits associated with corresponding features of the weft yarn control mechanism outlined above.
The weaving loom further includes a cycle of projectiles configured to, in turn, grip the weft yarn and be propelling by the propelling mechanism through the shed formed by the plurality of warp yarns.
According to a third aspect of the invention there is provided a method of controlling a weft yarn within a weaving loom deploying a cycle of projectiles gripping the weft yarn, the method comprising the steps of: propelling a projectile gripping the weft yarn in a first direction through a shed formed by a plurality of warp yarns; operating a valve arrangement in a first position in which the valve arrangement directs a propelling fluid towards the weft yarn to apply a force to the weft yarn in the first direction so as to assist in the propelling of the projectile; and switching the valve arrangement to a second position in which the valve arrangement directs a tensioning fluid towards the weft yarn to apply a force to the weft yarn in a second direction opposite to the first direction so as to tension the weft yarn and reduce overrun of the weft yarn.
The method of tensioning a weft yarn shares the benefits associated with corresponding features of the weft yarn control mechanism outlined above.
The method may further include the steps of: switching the valve arrangement back to the first position after a predetermined amount of time; and propelling another projectile gripping the weft yarn in the first direction through the shed formed by a plurality of warp yarns.
Such steps provides a repeatable weaving method.
Optionally the method further includes the step of: inputting a control program into a valve control unit to control the amount of time the valve arrangement is in the first and/or second positions.
Optionally the method further includes the step of: inputting a control program into a valve control unit to control the flow rate of the propelling and/or tensioning fluids.
Preferably the method includes the steps of: applying a brake mechanism to stop the weft yarn from travelling in the first direction; and switching the valve arrangement to operate in the second position when the brake mechanism is applied.
The method may further include the step of: inputting a control program into a brake control unit to control the amount of time the brake mechanism is applied.
There now follows a brief description of a preferred embodiment of the invention, by way of a non-limiting example, with reference to the accompanying drawings in which:
Figure 1 shows a weft yarn control mechanism according to an embodiment of the invention;
Figure 2a) shows a schematic view of the weft yarn control mechanism shown in Figure 1 when the weft yarn is being propelled;
Figure 2b) shows a schematic view of the weft yarn control mechanism shown in Figure 1 just before the weft yarn is stopped; and
Figure 2c) shows a schematic view of the weft yarn control mechanism shown in Figure 1 when the weft yarn is stopped. A weft yarn control mechanism according to a first embodiment of the invention is designated generally by reference numeral 10.
The weft yarn control mechanism 10 includes a propelling mechanism 12 which is configured to propel a projectile 16 gripping a weft yarn 14 in a first direction Di through a shed formed by a plurality of warp yarns (not shown).
The projectile 16 is configured to gip the weft yarn 14 via grippers (not shown) at one end of the weft yarn 14 and carry the weft yarn 14 in the first direction Di when it is propelled in the first direction Di. There would typically be a plurality of projectiles 16 which grip the weft yarn 14 and are, in turn, propelled through the shed formed by the warp yarns, i.e. a cycle of projectiles 16. In this way, the weft yarn tension control mechanism 10 can be used in combination with a projectile weaving loom (not shown).
In the embodiment shown, the propelling mechanism 12 is a mechanical mechanism such as an accelerating hammer that propels the projectiles 16 by driving them through the shed formed by the warp yarns. The propelling mechanism 12 may take any other suitable form to propel the projectiles 16 through the shed.
The weft yarn tension control mechanism 10 also includes a valve arrangement 18 including a fluid source 20. The valve arrangement 18 is moveable between a first position and a second position. In the first position, as shown in Figure 2a, the valve arrangement 18 is configured to direct a propelling fluid 22 towards the weft yarn 14 to apply a force to the weft yarn 14 in the first direction Di so as to assist in the propelling of the projectile 16. In the second position, as shown in Figures 2b) and 2c), the valve arrangement 18 is configured to direct a tensioning fluid 24 towards the weft yarn 14 to apply a force to the weft yarn 14 in a second direction D2 opposite to the first direction Di so as to tension the weft yarn 14 and reduce overrun of the weft yarn 14.
The valve arrangement 18 is also configured to switch from the first position to the second position after a predetermined time within each cycle of the projectiles 16 in the weaving loom.
In the embodiment shown, the valve arrangement 18 in the first position is configured to direct the propelling fluid 22 in the first direction Di such that the propelling fluid 22 flows in line with the direction of travel of the weft yarn 14. Moreover, the valve arrangement 18 in the second position is configured to direct the tensioning fluid 24 in the second direction D2 such that the tensioning fluid 24 flows in line with the opposite direction of travel of the weft yarn 14.
In other embodiments of the invention (not shown) the valve arrangement 18 may be configured to direct one or both of the propelling and tensioning fluids 22, 24 at an angle towards the weft yarn 14 (e.g. a fluid 22, 24 both directly above and beneath the weft yarn 14) such that the fluid 22, 24 does not flow in the first or second direction Di, D2 but it still applies a force to the weft yarn 14 in the respective first or second direction Di, D2.
The valve arrangement 18 may include one or several valves (not shown) which permit the switching between the first and second positions. The valve arrangement 18 also includes a nozzle (not shown) to direct the propelling and tensioning fluid 22,24 as desired.
In the embodiment shown, the propelling fluid 22 and the tensioning fluid 24 are the same fluid. In particular, the propelling and tensioning fluid 22, 24 is air.
In other embodiments of the invention (not shown) the propelling fluid 22 and the tensioning fluid 24 may differ from one another. Moreover, one or both of the propelling and tensioning fluids 22, 24 may be or include a liquid such as water.
The weft yarn control mechanism 10 further includes a valve control unit 26 which is configured to operate the valve arrangement 18 in accordance with a control program. In the embodiment shown, the valve control unit 26 forms part of a computer 28 into which an operative can input the control program.
The valve control unit 26 is configured to control the amount of time the valve arrangement 18 is in the first and second positions, and it is configured to control the flow rate of the fluid 22, 24 being directed from the valve arrangement 18.
The weft yarn control mechanism 10 further includes a brake mechanism 30 (shown in Figures 2a) to c)) which is configured to stop the weft yarn 14 from travelling in the first direction Di when the brake mechanism 30 is applied. In the embodiment shown, the valve arrangement 18 is configured to remain in the second position while the brake mechanism 30 is applied. The valve arrangement 18 may also be configured to switch to the second position when the brake mechanism 30 is applied.
The brake mechanism 30 includes a clamp 32, but it may take any other form which is capable of stopping the weft yarn 14 from travelling in the first direction Di.
In the embodiment shown, the valve arrangement 18 is configured to direct the tensioning fluid 24 towards the weft yarn 14 to apply a force to the weft yarn 14 in the second direction D2 before the brake mechanism 30 stops the weft yarn 14 from travelling in the first direction Di. In this way, the valve arrangement 18 is configured to slow the weft yam 14 before braking.
The weft yarn control mechanism 10 further includes a brake control unit 34 which is configured to operate the brake mechanism 30 in accordance with a control program which controls the amount of time the brake mechanism 30 is applied. In the embodiment shown, the brake control unit 34 forms part of the same computer 28 as the valve control unit 26, but in other embodiments it may instead form part of a separate computer.
Figures 2a) to c) show schematics of the weft yarn control mechanism 10 in use within a weaving loom deploying a cycle of projectiles griping the weft yarn (i.e. a projectile weaving loom).
In particular, Figure 2a) shows the weft yarn control mechanism 10 in use when the weft yarn 14 is being propelled in the first direction Di through the shed (not shown).
In this regard, the projectile 16 (not shown in Figures 2a) to c) for clarity purposes) grips an end of the weft yarn 14 and is propelled by the propelling mechanism 12 (also not shown in Figures 2a) to 2c) for clarity purposes) in the first direction Di. At the same time, the valve arrangement 18 operates in the first position and directs the propelling fluid 22 in the first direction Di towards the weft yarn 14 which helps to propel the projectile 16 and the weft yarn 14 in the first direction Di.
As shown in Figure 2b), after a predetermined amount of time, the valve arrangement 18 switches to operate in the second position and thus directs the tensioning fluid 24 in the second direction D2 towards the weft yarn 14. The tensioning fluid 24 in the second direction D2 applies a force to the weft yarn 14 in the second direction D2 and therefore begins to slow down the weft yarn 14 from its travel in the first direction Di.
Turning to Figure 2c), after a predetermined amount of time the braking mechanism 30 is applied and clamps the weft yarn 14 at a predetermined length of weft yarn 14, thereby stopping the weft yarn 14 from travelling in the first direction Di. The valve arrangement 18 continues to direct the tensioning fluid 24 in the second direction D2 which now tensions the stationary weft yarn 14 and eliminates or reduces the amount of overrun of the weft yarn 14.
The projectile 16 then releases the weft yarn 14 which can result in the projectile 16 pushing against the weft yarn 14, i.e. in the second direction D2. Such pushing normally causes the weft yarn 14 to become slack, however the tensioning fluid 24 being directed in the second direction D2from the valve arrangement 18 ensures that a constant tension of the weft yarn 14 is maintained while the projectile 16 releases the weft yarn 14.
After another predetermined amount of time, the braking mechanism 30 stops being applied and the valve arrangement 18 either switches to off (i.e. wherein no fluid is being directed therefrom) or to operate in the first position.
At this time, the projectile 16 travels back to a starting point within the projectile weaving loom so that it is ready to grip another weft yarn 14 and begin the whole process again. This is considered one cycle of the projectile 16 in the weaving loom.
In the event that the weft yarn type is being changed, e.g. from a polypropylene to a jute, an operative may change the control program of the valve control unit 26 and/or the brake control unit 34, as outlined below.
The control program may be changed so as to control the flow rate of the propelling and/or tensioning fluids 22, 24.
The control program may also be changed so as to control the amount of time the valve arrangement 18 is operating in the first position. As such, after the inputted amount of time the valve arrangement 18 will automatically switch to operate in the second position, i.e. to direct the tensioning fluid 24.
Alternatively, the valve arrangement 18 may instead be configured to switch to operate in the second position when the brake mechanism 30 is applied. Thus, a control program can be inputted to the brake control unit 34 to control when the brake mechanism 30 is applied, which automatically switches the valve arrangement 18 to the second position.
The control program may also be changed so as to control the amount of time the brake mechanism 30 is applied. In this example, the valve mechanism 18 may be configured to operate in the second position when the brake mechanism 30 is applied. As such, by altering the amount of time the brake mechanism 30 is applied you also control the amount of time the valve arrangement 18 is operating in the second position.
Alternatively, the amount of time the valve mechanism 30 is operating in the second position may be separately controlled by the control program. A combination of the above-described control programs may be used to achieve the desired overall timing of the projectile weaving loom and slack removal of the the weft yarn 14 for a particular fabric piece.

Claims (24)

CLAIMS:
1. A weft yarn control mechanism, for use with a weaving loom deploying a cycle of projectiles gripping a weft yarn, comprising: a propelling mechanism configured to propel a projectile gripping the weft yarn in a first direction through a shed formed by a plurality of warp yarns; and a valve arrangement including a fluid source, the valve arrangement being moveable between a first position and a second position, wherein in the first position the valve arrangement is configured to direct a propelling fluid towards the weft yarn to apply a force to the weft yarn in the first direction so as to assist in the propelling of the projectile, and wherein in the second position the valve arrangement is configured to direct a tensioning fluid towards the weft yarn to apply a force to the weft yarn in a second direction opposite to the first direction so as to tension the weft yarn and reduce overrun of the weft yarn.
2. A weft yarn control mechanism according to Claim 1 wherein the valve arrangement is configured to switch from the first position to the second position after a predetermined time within each cycle of the projectiles in the weaving loom.
3. A weft yarn control mechanism according to Claim 1 or Claim 2 wherein the valve arrangement in the first position is configured to direct the propelling fluid in the first direction.
4. A weft yarn control mechanism according to any preceding claim wherein the valve arrangement in the second position is configured to direct the tensioning fluid in the second direction.
5. A weft yarn control mechanism according to any preceding claim wherein the valve arrangement is configured to alter the flow rate of any fluid directed therefrom.
6. A weft yarn control mechanism according to any preceding claim further including a valve control unit configured to operate the valve arrangement in accordance with a control program.
7. A weft yarn control mechanism according to Claim 6 wherein the valve control unit is configured to control the amount of time the valve arrangement is in the first and/or second positions.
8. A weft yarn control mechanism according to Claim 6 or Claim 7 when dependent on Claim 5 wherein the valve control unit is configured to control the flow rate of the fluid being directed from the valve arrangement.
9. A weft yarn control mechanism further including a brake mechanism configured to stop the weft yarn from travelling in the first direction when the brake mechanism is applied, wherein the valve arrangement is configured to remain in the second position while the brake mechanism is applied.
10. A weft yarn control mechanism according to Claim 9 further including a brake control unit configured to operate the brake mechanism in accordance with a control program.
11. A weft yarn control mechanism according to Claim 10 wherein the brake control unit is configured to control the amount of time the brake mechanism is applied.
12. A weft yarn control mechanism according to any preceding claim wherein the tensioning fluid is or includes air.
13. A weft yarn control mechanism according to any preceding claim wherein the propelling fluid is or includes air.
14. A weaving loom comprising a weft yarn control mechanism according to any preceding claim.
15. A weaving loom according to Claim 14 further including a cycle of projectiles configured to, in turn, grip the weft yarn and be propelled by the propelling mechanism through the shed formed by the plurality of warp yarns.
16. A method of controlling a weft yarn within a weaving loom deploying a cycle of projectiles gripping the weft yarn, the method comprising the steps of: propelling a projectile gripping the weft yarn in a first direction through a shed formed by a plurality of warp yarns; operating a valve arrangement in a first position in which the valve arrangement directs a propelling fluid towards the weft yarn to apply a force to the weft yarn in the first direction so as to assist in the propelling of the projectile; and switching the valve arrangement to a second position in which the valve arrangement directs a tensioning fluid towards the weft yarn to apply a force to the weft yarn in a second direction opposite to the first direction so as to tension the weft yarn and reduce overrun of the weft yarn.
17. A method of controlling a weft yarn according to Claim 16 further including the steps of: switching the valve arrangement back to the first position after a predetermined amount of time; and propelling another projectile gripping the weft yarn in the first direction through the shed formed by a plurality of warp yarns.
18. A method of controlling a weft yarn according to Claim 16 or Claim 17 further including the step of: inputting a control program into a valve control unit to control the amount of time the valve arrangement is operating in the first and/or second positions.
19. A method of controlling a weft yarn according to any one of Claims 16 to 18 further including the step of: inputting a control program into a valve control unit to control the flow rate of the propelling and/or tensioning fluids.
20. A method of controlling a weft yarn according to any one of Claims 16 to 19 further including the steps of: applying a brake mechanism to stop the weft yarn from travelling in the first direction; and switching the valve arrangement to operate in the second position when the brake mechanism is applied.
21. A method of controlling a weft yarn according to Claim 20 further including the step of: inputting a control program into a brake control unit to control the amount of time the brake mechanism is applied.
22. A weft yarn control mechanism generally as herein described with reference to and/or as illustrated in the accompanying drawings.
23. A weaving loom generally as herein described with reference to and/or as illustrated in the accompanying drawings
24. A method of controlling a weft yarn generally as herein described with reference to and/or as illustrated in the accompanying drawings.
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US5816296A (en) * 1996-03-22 1998-10-06 Lindauer Dornier Gesellschaft Mbh Method and apparatus for controlling the tension and the presentation of a weft thread for insertion into a loom shed
US6009915A (en) * 1997-11-28 2000-01-04 Sulzer Rueti Ag Method and distribution apparatus for pneumatic weft insertion in a series shed loom
US20050217094A1 (en) * 2002-03-12 2005-10-06 Paer Josefsson Pneumatic thread tensioner and thread handling system
EP2230342A1 (en) * 2009-03-18 2010-09-22 ITEMA (Switzerland) Ltd. Storage device and method for storing weft threads in a loom

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US4637229A (en) * 1985-02-11 1987-01-20 Taylor James W Jr Pneumatic thread tensioning device
JPH02104749A (en) * 1988-10-13 1990-04-17 Osaka Denshi Kiki Kk Method for adding tension to yarn of loom and knitting machine and apparatus therefor
JPH06322642A (en) * 1992-10-02 1994-11-22 Micron Kiki Kk Apparatus for delivering weft yarn of fluid jet type loom
EP1408144A3 (en) * 2002-10-10 2004-12-22 Tsudakoma Kogyo Kabushiki Kaisha Weft tension device of a loom

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4410018A (en) * 1980-09-09 1983-10-18 Sulzer Brothers Limited Nozzle structure for a weaving machine
US5816296A (en) * 1996-03-22 1998-10-06 Lindauer Dornier Gesellschaft Mbh Method and apparatus for controlling the tension and the presentation of a weft thread for insertion into a loom shed
US6009915A (en) * 1997-11-28 2000-01-04 Sulzer Rueti Ag Method and distribution apparatus for pneumatic weft insertion in a series shed loom
US20050217094A1 (en) * 2002-03-12 2005-10-06 Paer Josefsson Pneumatic thread tensioner and thread handling system
EP2230342A1 (en) * 2009-03-18 2010-09-22 ITEMA (Switzerland) Ltd. Storage device and method for storing weft threads in a loom

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