A device and method for turret positioning in automatic yarn winder
Field of Invention:
The present invention relates to a turret type automatic winding method and apparatus. In particular, the invention relates to the means for relative positioning of spindle and the pressure roller.
Terms used:
In the following description, the term "yarn" is intended to also include the threads, tapes, profile tapes, fibrillated tapes and slit-film bands of various linear mass density, diameter, width and thickness. The term "bobbin" is intended to include any metallic or non-metallic bobbins on which the yarn is wound to form a suitable package. The term 'yarn' is also used to describe yarn with multiple threads or ends that a single winder might receive.
Background of the invention:
The conventional winders consist of rotating spindle and reciprocating traverse guide which is mounted in cam box housing and pivoted through swivel arm. There is also a freely rotating roller mounted on arm/bracket which is secured


with cam box/traverse housing. This roller is known as "bail roller" or "pressure roller" which maintain at all time contact with the periphery of package being formed and ensures uniformity of shape and density of the yarn package by application of uniform pressure. In conventional winder with manual doffing and single spindle, the gap between pressure roller and bobbin on spindle at the start of winding can be accurately adjusted and repetitively maintained. This gap is necessary for the yarn to start getting wound around the bobbin. As the yarn package takes shape, the package makes contact with the pressure roller throughout the rest of the formation of package. This is typically achieved through the pressure applied on the pressure roller.
In automatic turret type winders, a continuously advancing yarn is generally wound on an initially empty bobbin to form a suitable yarn package. At the start of the winding operation, an empty bobbin is installed on one of the bobbin holders, generally known as a spindle. When the pre-determined package size (determined by the length or diameter of the package that is formed, or by the time taken to form the package) is achieved, the continuously advancing yarn is transferred by an automatic transfer device to another empty bobbin installed on another spindle.
In the automatic turret winders, the process of yarn transfer for forming new packages is carried out without interrupting the winding operation. The spindles are alternatively moved to the winding position and simultaneously the cam box with pressure roller is swung radially to and fro from the spindle in winding

position. One drawback of such winders is that they require special control mechanisms to set up the initial minimum gap between the pressure roller and bobbin on spindle before the winding start-up operation and also to repetitively maintain distance between spindle and pressure roller after bobbin changeover operation. Some such mechanisms, such as a servo motor or a stepper motor, are disclosed in US patent 5489067. Some other complicated methods are described in the US patents 5029762, 5016829, and 5605294.
If the initial relative positioning of spindle with the pressure roller is not controlled uniformly and repetitively after bobbin changeover operation, it results in non-uniform yarn layer at the start of the formed package. Packages without uniformly layered yarn result in tension variation in processes where the yarn packages are used, particularly on looms. The unevenly formed packages also lead to more fabric width variation and/or wastage of material in subsequent operation. Further, when the relative position of spindle and pressure roller is such that the gap between them is kept to a bare minimum (the 'optimal' gap), the chance of yarn transfer failure during bobbin changeover is very high, particular in case of heavy denier yarns or slit film bands. Thus to achieve higher yarn transfer efficiency, the starting or initial gap between spindle and pressure roller should be higher than optimum gap between spindle and pressure roller required for best yarn package winding.

The conventional mechanisms that control the initial gap between the pressure roller and the bobbin comprise a number of components, and are complex and costly. There are several factors that influence the accuracy with which the gap is maintained within acceptable variation range during the winding start-up operation. These factors are manufacturing accuracy of the components, the fact that the turret moves rotationally, inertia of the cam box, and the sensitivity of the brake and the sensors. All these factors cumulatively cause a high level of variation in the gap and maintaining the minimum gap between the bobbin and pressure roller within an acceptable level, before the winding start-up is a great concern.
It has also been observed that with the use of low-cost drive means, such as frequency inverters, for various operations and low-cost controlling techniques have meant that the accurate repeatability of spindle positioning at the start of each winding operation is almost impossible to achieve.
Thus, there is need to provide a simple, cost effective control mechanism for controlling the minimum gap between the bobbin on spindle and pressure roller initially before winding start-up and repeatability of same thereafter for each and every bobbin changeover operation.

Objectives:
The primary objective of this invention is to provide a simple, cost effective control mechanism for controlling the minimum gap / relative positioning between the bobbin on spindle and pressure roller initially before winding start-up.
A further objective of the device of the present invention is to maintain repeatability of the minimum gap / relative positioning between the bobbin on spindle and pressure roller initially before winding start-up for each and every bobbin changeover operation.
Another objective of the present invention is to increase the yarn transfer efficiency during the bobbin change-over operation.
These and the other objects of this invention will become apparent from the description and the accompanying drawings that follow.
Brief description of figures:
Figure 1 show an automatic turret winding machine showing a turret and the
spindles mounted thereon
Figure 2 shows the non-operating position of the winding machine during the
bobbin changeover operation
Figure 3 shows the turret in a fully rotated position whereby fully wound package
is moved to the doffing position and yarn transferred onto new bobbin


Figure 4 shows the spindle and the pressure roller in a position of the minimum gap between them after the reverse rotation of turret.
Summary of the invention
The invention discloses a device to accurately position the turrets in automatic yarn winding devices. In a continuous yarn winding operation, the turret carrying bobbins is rotated such that a bobbin carrying fully formed package is moved from its winding position to a doffing position through an amount slightly greater than 180°. The turret is then rotated in a reverse direction to form a starting gap between the empty bobbin newly arrived at the winding position and the pressure roller. This method of a first rotation of the turret followed by a much smaller reverse rotation provides a very accurate formation of the starting gap that is required for a successful yarn transfer and winding operation.
List of parts:
Turret 1 Yarn transfer means 8
Spindles 2A and 2B Yarn 9
Pressure Roller 3 Arm/ brackets 10
Bobbin/bobbin core 4 Pivot axis 11
Fully wound package 5 Swivel arm 12
Guide 6 Gap 13; First gap 13A; Second gap 13B
Traverse means 7

Description of the invention and its preferred embodiments:
Figure 1 shows an automatic turret winding machine having a turret 1 on which two spindle (2A, 2B) are mounted. The turret 1 is rotatable such that in a continuous winding operation typically successive 180° rotations (typically clockwise) of the turret causes the two spindles 2A, 2B to be alternatively switched between the winding position and the doffing position. A typical winding machine also comprises a pressure roller 3 disposed to contact the periphery of a package 5 being wound on a bobbin 4 in the winding position, and movable in the machine so as to remain in contact with package 5 being formed, under positive pressure, until completion of winding operation. The winding machine typically further comprises control means (not shown in figures) to control movements of the turret and other parts such as the guide 6 and the traverse means 7 when a predetermined package size is achieved. This could typically correspond to a wound package of predetermined size in the case of automatic operations or an intentional manual activation of doffing signal.
Operation of the apparatus of the invention:
A continuously arriving yarn 9 is being wound into a package 5 by winding the yarn 9 around a bobbin 4 which is secured on the spindle 2A which is in the winding position. The advancing yarn is laid on the surface of the bobbin 4 or package 5 by means of a rotating pressure roller 3 (either freely rotating or

positively driven), which is mounted on arm/bracket 10. The traverse mechanism 7 and the arm 10 are arranged to pivot together about a pivot axis 11 using a swivel arm 12, so that the pressure roller 3 can continuously maintain contact with the package 5 being formed as the diameter of the package 5 increases during winding. The formation of a gap 13 of right size between the pressure roller 3 and the bobbin 4 at the start of the package formation is crucial for the uniform and consistent package formation.
Once the package 5 has achieved the predetermined size, the spindle changeover operation begins. The control means then initiates the yarn transfer operation by causing the activation of a pneumatic cylinder (not shown) of the swivel arm 12. The retraction of the pneumatic cylinder causes a partial rotational (clockwise in the present case) movement of the swinging swivel arm 12 thereby disengaging the traverse means 7 and moving it away from the spindle 2B. Thus the guide 6 and traverse means 7 are moved from their own operating positions (that is when the roller 3 is close to the bobbin 4 that is being wound as shown in Figure 1) to their non-operating positions (that is when the roller 3 is moved away from the winding position as shown in Figure 2).
Next, the control means then rotates the turret 1 (clockwise in the present case) to
move the fully wound package 5 from the winding position to its doffing position.

This rotation, denoted as the first rotation, is typically 180° in conventional turret type winding machines. Typically at the same time as the turret rotation is taking place, the control means, moves the traverse means 7 by a partial rotational movement of the swinging swivel arm 12 (anticlockwise in the present case) back to its own operating position. Further, the control means make the yarn transfer means 8 operable after a suitable time interval when the guide 6 means is in the operating position, for successfully transfer the yarn onto new empty bobbin 4.
The operating positions of various parts of the typical automated turret type winding machine, namely the swivel arm, pressure roller, guide means, traverse means, are well known to a person skilled in the art.
In accordance with the most preferred embodiment of this invention the first rotation of the turret, indicated by angle 9i, from the winding position to the doffing position is kept slightly more than the conventional 180° (see figure 3). It is evident from Figure 3 that once the first rotation (clockwise in this case) of the turret is thus complete and when the traverse means 7 along with pressure roller 3 is brought in towards the spindle 2B by the displacement of pneumatic cylinder, there exists a slightly-larger-than-necessary gap (named as first gap 13A) between the spindle 2B and the pressure roller 3. The control means also initiates the yarn

transfer mechanism to complete its operation. Thus the continuously advancing yarn starts getting wound on the new bobbin mounted on spindle 2B.
One characteristic feature of the present invention is that at this stage the control means rotates the turret 1 in opposite direction (anticlockwise in the present case) preferably by an angle θ2. θ2 being preferably a few degrees in magnitude, so as to reduce the first gap such that minimum gap (termed as second gap 13B) between spindle 2B and pressure roller 3, required for optimal yarn winding operation, is achieved.
In a further embodiment of the present invention, in order to further reduce the variation range of second gap 13B between pressure roller 3 and the bobbin 4, suitable mechanical means such as a stopper, an O-ring and/or pressure roller etc can be provided against which the bobbin 4 will be rested after the second rotation of turret by θ2. Thus repeatability of second gap 13B is achieved more accurately.
The magnitude of the second gap is determined based on the yarn layer thickness;
such that the yarn transfer onto bobbin mounted on spindle 2B is facilitated with
ease. The machine is then in the condition as illustrated in figure 4, which
represents the start of winding operation on an empty bobbin. As the package

formation starts, the pressure roller makes and maintains contact with the package that is being formed.
One key advantage of the present invention is that the simple step of inverse rotation provides an easy, inexpensive, consistent and repeatable means to create the minimum optimal gap (the second gap) between the pressure roller 3 and the spindle 2B and that the success rate of yarn transfer/changeover mechanism is higher.
Winding of a package on the bobbin 4 then proceeds normally until the condition illustrated in figure 1 is reached once again, whereupon the complete transfer operation is repeated.
In an embodiment of the invention, the winding machine may also comprise a deflecting means, in which case the control means are designed to move the deflecting means so as to disengage the traverse means 7 from the spindle 2A before rotating the turret 1, and to retract the deflecting means so as to allow the traverse means 7 to move back from the non-operating position to the operating position before operating the yarn transfer 8.

In a still further embodiment of the invention, the second rotation is such that the bobbin 4 rests against the pressure roller (in other words, the magnitude of the second gap is zero).
The key advantage of the process of the present invention is that by simple means as described herein, the minimum gap between spindle and pressure roller can be achieved with high consistency and repeatability. There is no formation of disturbed layer or non uniform package leading to formation of better uniform package with automatic bobbin changeover winder. The number of instances of successful yarn transfer during the bobbin changeover is much higher than in the case of the conventional systems thus improving the machine productivity.
Alternative embodiments of repositioning of turret and/or traverse housing positional arrangement in accordance with invention will be readily apparent to persons skilled in art. For example movement of traverse housing means and traverse guide means may be by means of linear motors, hydraulic or pneumatic means as desired. As further alternative, the traverse mechanism and pressure roller may move linearly towards and away from the winding position instead of being mounted for pivotal movement as described herein.

It is evident from the forgoing discussion that the present invention comprises the following items:
1. A device for turret positioning in an automatic turret type yarn winding machine, said device comprising a winding machine with an automated turret, and a yarn winding and transfer mechanism,
said device being characterized in that
in an continuous yarn winding and transfer operation, the automatic turret undergoes a first rotation θ1 to take a fully wound package from its operating position to its doffing position, and the swivel arm rotates, either simultaneously, subsequently or prior, from its own operating position to its own non-operating position and back again to its own operating position,
the amount of first rotation θ1 of said turret is so as to create a predetermined first gap between the winding position of the empty bobbin to be wound and the pressure roller in its own operating position,
and said first gap is then reduced by a second rotation θ2 of said turret, said second rotation being in a direction reverse to that of said first rotation, so that a second gap is formed between said bobbin and said pressure roller, said second gap being suitable for the yarn being wound, such that soon after start of the package formation said pressure roller comes in the

contact with the surface of the package being formed and stays in contact with it.
2. A device for turret positioning as claimed in claim 1 wherein said first rotation is preferably between 180° to 195°, more preferably between 180° to 185°, even more preferably between 180 ° to 183 °.
3. A device for turret positioning as claimed in claims 1 and 2 wherein said second rotation is preferably between 0° to 15°, more preferably between 0° to 5°, even more preferably between 0° to 3°.
4. A device for turret positioning as claimed in claims 1 to 3, wherein either said first rotation and said second rotation or both said rotations takes place in multiple stages in quick successions.
5. A device for turret positioning as claimed in claims 1 to 4, wherein said yarn is a film tape with a large width-to-thickness ratio, preferably with or without fibrillation.
6. A device for turret positioning as claimed in claims 1 to 5 wherein the magnitude of said second gap is zero.
7. A device for turret positioning as claimed in claims 1 to 5 wherein the formation of said second gap is controlled by suitable mechanical means such as a stopper or an O-ring.
8. A method for turret positioning in an automatic yarn winding machine wherein said method comprises the following steps:

providing a device for turret positioning, said device comprising a winding machine with an automated turret, and a yarn winding and transfer mechanism,
disengaging the traverse means to move the swivel arm away from its operating position, and rotating the turret to cause a first rotation to move the fully wound package from winding position to a doffing position, optionally simultaneously, with the movement of the swivel arm, characterized in that the amount of first rotation of said turret is greater than 180°,
rotating said swivel arm in a reverse direction to its earlier rotation by an amount so that a first gap is maintained between the pressure roller and the empty spindle, - rotating said turret so as to adjust the first gap to form a second gap, said second gap being of optimal value to cause successful yarn winding.
9. A method for turret positioning in an automatic yarn winding machine as claimed in claim 6 wherein said first rotation is preferably between 180° to 195°, more preferably between 180° to 185°, even more preferably between 180° to 183°.
10. A method for turret positioning in an automatic yarn winding machine as claimed in claims 8 and 9 wherein said second rotation is preferably between 0° to 15°, more preferably between 0° to 5°, even more preferably between 0° to 3°.

11. A method for turret positioning in an automatic yarn winding machine as claimed in claims 8 to 10, wherein said first rotation takes place in multiple stages in a quick succession.
12. A method of turret positioning in automatic winding machine as claimed in claims 8 to 11, wherein said yarn is a film tape with a large width-to-thickness ratio, preferably with or without fibrillation.
13. A method of turret positioning as claimed in any of the above claims, wherein the formation of said second gap is controlled by suitable mechanical means such as a stopper or an O-ring.
While the above description contains much specificity, these should not be construed as limitation in the scope of the invention, but rather as an exemplification of the preferred embodiments thereof. It must be realized that modifications and variations are possible based on the disclosure given above without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.

We claim:
1. A device for turret positioning in an automatic turret type yarn winding machine, said device comprising a winding machine with an automated turret, and a yarn winding and transfer mechanism,
said device being characterized in that
in an continuous yarn winding and transfer operation, the automatic turret undergoes a first rotation θ1 to take a fully wound package from its operating position to its doffing position, and the swivel arm rotates, either simultaneously, subsequently or prior, from its own operating position to its own non-operating position and back again to its own operating position,
the amount of first rotation θ1 of said turret is so as to create a predetermined first gap between the winding position of the empty bobbin to be wound and the pressure roller in its own operating position,
and said first gap is then reduced by a second rotation θ2 of said turret, said second rotation being in a direction reverse to that of said first rotation, so that a second gap is formed between said bobbin and said pressure roller, said second gap being suitable for the yarn being wound, such that soon after start of the package formation said pressure roller comes in the
contact with the surface of the package being formed and stays in contact with it.
2. A device for turret positioning as claimed in claim 1 wherein said first rotation is preferably between 180° to 195°, more preferably between 180° to 185°, even more preferably between 180° to 183°.
3. A device for turret positioning as claimed in claims 1 and 2 wherein said second rotation is preferably between 0° to 15°, more preferably between 0° to 5°, even more preferably between 0° to 3°.
4. A device for turret positioning as claimed in claims 1 to 3, wherein either said first rotation and said second rotation or both said rotations takes place in multiple stages in quick successions.
5. A device for turret positioning as claimed in claims 1 to 4, wherein said yarn is a film tape with a large width-to-thickness ratio, preferably with or without fibrillation.
6. A device for turret positioning as claimed in claims 1 to 5 wherein the magnitude of said second gap is zero.
7. A device for turret positioning as claimed in claims 1 to 5 wherein the formation of said second gap is optionally or additionally controlled by suitable mechanical means such as a stopper or an O-ring.
8. A method for turret positioning in an automatic yarn winding machine wherein said method comprises the following steps:
providing a device for turret positioning, said device comprising a winding machine with an automated turret, and a yarn winding and transfer mechanism,
disengaging the traverse means to move the swivel arm away from its operating position, and rotating the turret to cause a first rotation to move the fully wound package from winding position to a doffing position, optionally simultaneously, with the movement of the swivel arm, characterized in that the amount of first rotation of said turret is greater than 180°,
rotating said swivel arm in a reverse direction to its earlier rotation by an amount so that a first gap is maintained between the pressure roller and the empty spindle, - rotating said turret so as to adjust the first gap to form a second gap, said second gap being of optimal value to cause successful yarn winding.
9. A method for turret positioning in an automatic yarn winding machine as claimed in claim 6 wherein said first rotation is preferably between 180° to 195°, more preferably between 180° to 185°, even more preferably between 180° to 183°.
10. A method for turret positioning in an automatic yarn winding machine as claimed in claims 8 and 9 wherein said second rotation is preferably between 0° to 15°, more preferably between 0° to 5°, even more preferably between 0° to 3°.
11. A method for turret positioning in an automatic yarn winding machine as
claimed in claims 8 to 10, wherein said first rotation takes place in
multiple stages in a quick succession.
12. A method of turret positioning in automatic winding machine as claimed
in claims 8 to 11, wherein said yarn is a film tape with a large width-to-
thickness ratio, preferably with or without fibrillation.
13. A method of turret positioning as claimed in any of the above claims,
wherein the formation of said second gap is controlled by suitable
mechanical means such as a stopper or an O-ring.