Field of Invention:
The invention relates to slit film tape or yarn winding type device and a process to
control yarn tension during winding such that consistent unwinding yarn tension
can be achieved in relation to bobbin package diameter.
5
Background of Invention:
A yarn winder is used for winding of continuously arriving yarn of polyolefin —
flat/fibrillated or any similar type— onto a bobbin. Here, yarn defines flat tapes,
multifilament and monofilament yarns or any similar type of yarns or tapes. In
10 general, bobbin holders, also known as mandrel cores, are mounted on spindles on
each winder machine frame. Each spindle needs precisely controlled rotation, so
may be driven independently by an electric motor through a suitable mechanism
such as a belt and pulley arrangement or with a direct driving system.
Conventionally, the encoders or other similar devices for pulse generation are
15 mounted on the motor for monitoring the motor revolutions, and the signal
therefrom is communicated to the electronic controller with the help of suitable
cable. The controller further sends the electrical signals to the inverter/drive of the
active motor which determines the power to be given for the motor driving the
spindle.
20
The conventional winders of the above type are disclosed in the US Patent Nos.
5228630, 4765552 and European Patent 861800A2.
3
In these conventional winders, yarn winding tension is controlled by regulating
tightening of the oscillating arm tensioning spring (hereinafter referred to as a,
dancing arm resistance for onwards references). The to and fro motion of dancing
arm is monitored electronically to keep yarn delivery at nearly uniform tension
with constant linear speed to spindle5 .
Wound bobbins produced from winders are used for further in line applications as
necessary. One of the major applications of wound bobbins is in formation of
tubular sacks on Circular Weaving Machines, which are also known as Circular
10 Weaving Looms (CWM/CWL). Circular looms contain plurality of bobbins of slit
film tapes used as weft and warp. Weft bobbins are arranged around a circular
reed ring, such that as the main shaft drives the central part, weft bobbins start
moving along the reed ring path and woven fabric produced is taken off by the
fabric take off unit.
15
In conventional winders, winding tension of yarn is maintained by providing
resistance to the motion of the dancing arm by adjusting spring attached to it.
Position feedback of dancing arm is routed to the control logic of winders, which
in turn rotate the bobbin mandrel such that a position of dancing arm is
20 maintained consistently with least oscillation. To maintain the winding tension for
various types of yarn of different properties like denier, width etc., the spring
attached to the dancing arm is adjusted such that its variation is minimized as
much possible to achieve good quality of produced bobbins. Conventionally,
4
spring associated with dancing arm is set once at the start of the winding process,
which remains constant throughout build of the bobbin as product. When the yarn
from the bobbins is used as the weft yarn on a circular loom, its unwinding
tension increases as the size of the bobbin decreases. This might be due to high
pulling force required for rotating the bobbin at increased angular velocity, or an5 y
other unidentified reasons during winding. This increase in yarn unwinding
tension results in undesirable variation in the fabric width – particularly so as weft
bobbin size reduces with time. This, however, also increases necking of the fabric
produced and sometimes breakage due to high weft tension.
10
To produce a good quality fabric of uniform width (or fabric without unacceptable
variation in width), it is necessary to vary the tension in the weft bobbin tape,
especially below a certain bobbin size. This variation in tension is carried out
gradually or discretely from a lower to higher level as the bobbin size grows.
15
There is therefore a need to develop a method of changing yarn winding tension
such that when same bobbin is unwound, the weft tension is lower compared to
conventionally wound bobbin at same bobbin size, to generate uniform quality
woven fabric.
20
Objects of the invention:
Accordingly, it is an object of the present invention to provide an automatic
method of stepwise or gradually or discretely varying the dancing arm stiffness or
resistance to its motion in relationship to build bobbin size.
5
Another object of the present invention is to reduce the width variation of fabric
produced by using yarn from these bobbins.
Summary of Invention5 :
The invention discloses an apparatus for regulating winding tension as function of
bobbin (2) diameter in a slit film tape or yarn (1) winder system carrying at least
one automated winder. It comprises a dancing arm (3) equipped with a tension
setting means or device (3B) which regulates the yarn tension. The instantaneous
10 position (3F) of said dancing arm (3) and resistance 'R' to movement of said
dancing arm (3) during the winding process are variable. The inventive feature of
the invention being provision of a tension setting means (3B) of changing
resistance 'R' of the dancing arm (3) as a function of the bobbin (2) diameter 'D'
during the winding process. The invention also provides a method for regulating
15 winding tension as function of bobbin (2) diameter in a slit film tape or yarn (1)
winder system. The invention helps overcome a number of problems related to
uniformness and consistency of package the fabric making industry is currently
facing. It solves technical problem of winding bobbin throughout using same
tension adjusted for dancing arm, resulting higher tension during unwinding at
20 low bobbin sizes. It also helps reduce the necking or shrinkage of the fabric
produced due to varying resultant winding tension.
6
List of parts:
Slit film tape (1)
Spindle with Bobbin (2)
Dancing Arm (3)
Dancing Arm Rollers (3A)
Tension setting device (3B)
Dancing Arm Movement Delimiter
(3C)
Dancing Arm in optimal operating
Position (3D)
Dancing Arm in End Position (3E)
Dancing arm at Instantaneous
Position (3F)
Tensioning Bow (4)
CAM Box (5)
Pressure Roller (6)
Slit film tape Guide (7)
MMI (8)
Parent Controller (9)
Winder head controller (10)
Pressure lines (11A and 11B))
Communication bus (12)
Brief description of figures:
The objects and advantages of the invention thereof may be understood by
making reference to the following description, taken with the accompanying
drawings5 :
Figure 1 shows a schematic of winder with oscillating Dancing Arm for slit film
tape winding with a tension control knob
Figure 1A shows the schematic of apparatus of the invention with a tension
setting means/device deployed in a winder with oscillating Dancing Arm for slit
10 film tape winding
7
Figure 2 shows a schematic of a two-step winding tension control logic of the
invention
Figure 3 shows a schematic of MMI, parent controller and winder head
controllers
Figure 4 shows the tape running over the tensioning bow, the pressure roller an5 d
the tape guide in action.
Detailed Description of the invention:
Figure 1A shows the apparatus of the invention. The invention discloses an
10 apparatus for regulating winding tension as function of package diameters of
bobbins that are used in a tapeline that deploys a number of bobbins (2) on which
yarn (1) or slit-film tapes are wound to form packages. The apparatus uses a
tension setting means (3B) for changing the variable resistance 'R' of a dancing
arm (3) as a function of the bobbin/package diameter ‘D’. The apparatus is used
15 for all types of yarns (1). The relationship between R and D is generally
represented by a function 'f' as:
R = f(D) Eq. 1
20 In a preferred embodiment the tension setting means (3B) of the apparatus -
which controls the dancing arm (3) resistance ‘R’ in a gradual manner (i.e.
changing pressure continuously) or in discrete steps – is a pressure line
multiplexer (which selects a pressure line at any instance). In a pressure line
8
multiplexer or pressure line multiplexing system, at least one (preferably two or
more) of pressure lines (11A and 11B, for example) is connected for sourcing
pressure. The pressure line multiplexer (3B) is also provided with a pressure line
selection switch (not shown). In one aspect of the invention where two pressure
lines (11A and 11B) are provided, only one of the pressure lines (11A and 11B) i5 s
selected using the pressure line selection switch at a time and the pressure is
transmitted to the dancing arm (3) for generating resistance R. This is illustrated
with a schematic example shown in Figure 2 for two discrete levels. Figure 2
shows two pressure lines (11A and 11B) out of which any one line is active at any
10 time. This can be suitably improved by using multilevel (or multi-stage or multistepped)
multiplexing or a system to achieve continuously/gradually changing
resistance ‘R’.
The apparatus of the invention controls the dancing arm resistance ‘R’ in a
15 gradual manner or in discrete steps by changing pressure continuously, or by
selecting a pressure line at an instance. In a pressure line multiplexing system, a
number of pressure lines can be sourced, but only one of them is selected for
activation at a time and the pressure is forwarded to Dancing arm (3) for
producing resistance ‘R’ to its oscillating movement.
20
The present invention also discloses a method for regulating winding tension as
function of bobbin (2) diameter which dynamically changes set resistance of the
dancing arm (3) during the yarn winding process by using pneumatic, or
9
magnetic, or electromagnetic braking technology. The method disclosed by the
invention involves determining at what point of bobbin (2) formation (bobbin
diameter), the pressure exerted on the dancing arm by the pressure lines (11A and
11B) (and effectively the dancing arm resistance) needs to change. This is done
on the basis of the pre-set relationship between R and D, which relationship i5 s
determined by individual users based on their own requirements and experience.
The ideal operating pressure (the pressure exerted by the pressure line multiplexer
on the dancing arm for optimal winding/package results) depends on bobbin
diameter and would be known to a person skilled in the art. This pressure is
10 optimized by the user for better quality of winding with optimum required
tension. As the package grows in diameter, the pressure requirement changes. The
optimal pressure is the pressure which sets resistance R to movement of the
dancing arm to a level at which the package is wound with the correct tension in
the yarn.
15
The relationship between package diameter and the pressure exerted by the
tension setting means/device (3B) (or consequently the resistance 'R') is thus
predetermined by the user. The preferred embodiment provides a two-stage
pressure setting system. The inventors have found that, typically, the set tape (1)
20 tension preferably lies between 0.08 cN to 0.1 cN per Denier. For example, if tape
(1) denier which is getting wound on bobbin is 800, then system set tape tension
must be in between 64 cN to 80 cN range. Based on these desired tape (1)
tensions, knob settings are selected manually in current winding systems.
10
Typically, in conventional winders, the resistance R of the dancing arm (3) to its
oscillating movement during the winding process is controlled by settings of a
knob which can be set at various positions by adjusting torsion of the spring that
is provided in the knob, which effectively increases stiffness of the dancing arm
(3) system according to yarn (1) properties5 .
In Figures 1, yarn ‘1’ delivered from direction ‘a’ after cutting and conditioning
from a tape line machine passes through a dancing arm roller (3A). A winder
starts winding as the running yarn (1) passing through dancing arm (3) roller (3A)
10 causes the dancing arm (3) to assume its instantaneous position (3F) due to the
yarn tension required for winding.
Also as shown in Figures 1 and 4, a CAM box assembly (5) constitutes a pressure
roller (6), a tape guide (7), a tensioning bow (4) along with other assembly parts.
15 The yarn (1) travels over the tensioning bow (4) before passing through the split
film tape guide (7).
The pressure roller (6) presses the spindle (2) to maintain winding tension. The
spindle rotational speed is electronically controlled in a closed loop as per
20 feedback provided (see Figure 2) on the dancing arm (3) deflection (i.e.
information on the instantaneous position (3F) of the dancing arm (3) is
monitored using a position sensor, relative to its optimal operating position (3D)
during the winding operation) so as to provide optimal tension in the yarn. The
11
optimal operating position (3D), as the name indicates, is the target position of the
dancing arm (3) during the winding operation to achieve optimal package
characteristics. However, during the winding operation, depending on the winding
process parameters, the dancing arm (3) typically deviates from its optimal
operating position (3D). The dancing arm (3) is arranged/designed such that as i5 t
is deflected angularly from its optimal operating position (3D) position, the
spindle (2) starts rotating and thus yarn winding starts on spindle. The extreme
positions (3E) which the dancing arm (3) is allowed to assume during a winding
operation are facilitated by provision of a dancing arm (3) movement delimiter
10 (3C – not shown).
Typically, in the conventional devices, the setting of the tension setting knob is
not changed during entire winding process. As a part of the closed loop, a position
sensor which is mounted on dancing arm (3) regularly transmits details of the
15 instantaneous position (3F) of dancing arm (3) to a winder head controller (10).
Based on these details the machine operator makes a decision regarding manually
tightening or loosening of the yarn (1). For instance, if the instantaneous position
(3F) of the dancing arm (3) is such that the dancing arm (3) deflects from its
optimal operating position (3D) towards the winding bobbin (2) then yarn (1) is
20 travelling in a looser-than-desired state. On the other hand, if the dancing arm
deflects away from its optimal operating position (3D) in a direction away from
the winding bobbin 2), then yarn is traveling in a tighter-than-desired state.
According to the instantaneous position (3F) of the dancing arm (3) deflection,
12
positional details of the dancing arm (3) are communicated to the winder head
controller (10) and thus the speed of spindle is regulated to control yarn
tensioning.
As stated earlier, a major disadvantage of conventional yarn winding methods i5 s
that these are carried out at a constant knob setting, which in turn results in
necking or shrinkage of the fabric produced due to varying resultant winding
tension, and sometimes in undesired frequent weft breakages.
10 The pressure multiplexing system used in the present invention preferably uses
pneumatic technology; however, it can also be implemented by using other
technologies such as magnetic or hydraulic braking or any other technology
existing or developed in future that can be used for applying braking. The device
of the invention facilitates a procedure for changing the dancing arm oscillating
15 resistance R proportionally to the bobbin diameter. The winder of the invention
may be the conventional yarn winders or winders modified to use suitable
pneumatic or hydraulic or magnetic systems to achieve winding functionality.
In figure 2, the functional diagram with preferred embodiments is described. A
20 Man Machine Interface (MMI) (8) is provided for entering the desired
machine/process related parameters of the winder machine (such as the yarn
denier, weight, speed, the tube outer diameter), which are known to a person
skilled in the art. The MMI (8), a parent controller (9) and winder head controller
13
(10) communicate with each other either over serial or parallel bus backbone. The
parent controller (9) is a channel for data-entering-point into an assembly of such
winder units, whereas a winder head controller (1) (or simply a head controller) is
a controller for each winder unit. There may be more than one winder unit in a
winder family5 .
Similar to conventional systems, the parent controller (9) is provided to transfer
data to all winder head controllers (10) for their operational requirements and
functionality. Parent controller (9) thus transfers process data such as the line
10 speed, winding recipe, etc. from each winder to respective winder head controllers
(10). There may be more than one winder head controller (10); all winder head
controllers (10) are connected to a single 'parent' controller (9) (also termed as the
'gateway' controller).
15 One of the embodiments of the present invention discloses a method where
multiple control lines (or pressure lines, for example 11A and 11B) are supplied
to line multiplexer and selected line (11A or 11B) is connected to the dancing arm
(3) for control of resistance R according to yarn (1) properties. The variation in
resistance can also be implemented by other means of braking which can be
20 continuous or discrete in nature of application. The source of control of resistance
‘R’ can be pressure (applied to the pivot point of the dancing arm (3), about which
the dancing arm (3) swings) or any other technique for controlling the winding
tension.
14
As an illustration, Figure 3 shows two pressure lines (11A and 11B). According to
the invention, one of the multiplexed pressure lines (11A or 11B) is connected to
the dancing arm (3) at any time. The pressure line (11A or 11B) thus replaces the
conventional torsional spring for adjusting oscillating resistance of the dancing
arm (3). The pressure line multiplexer (12) is an electromechanical control devic5 e
(for example, pneumatic valves which are electronically controlled for turning on
or switching off) for selecting one line at a time to connect with dancing arm (3).
The pressure settings of the pressure lines (11A and 11B) can be changed
10 manually or automatically according to the required pressure adjustment suitable
for proper winding. The pressure settings depend on yarn properties required for
optimal winding. Preferably, the pressure settings, the package cutoff size, and the
final package size, are input using the MMI (8) prior to starting the winding
operation. However, the settings may be adjusted during the winding process,
15 without halting the winding operations.
The winder head controller (10) carries information about cutoff bobbin size of
the package above which line-switching is required for optimal bobbin winding.
As the cutoff bobbin size of the package is reached, winder head controller (10)
20 generates a control signal to switch pressure lines. Bobbin size cutoff value is
entered by the machine user on MMI (8) which communicates the bobbin size cut
off value to winder head controllers (10) which are available on communication
bus (12) (see Figure 3). The ultimate size a package is allowed to reach is
15
typically set before the winding operation is started, however, it may be adjusted
during the winding operation.
It is possible to have different settings for different bobbins (2) that are being
wound simultaneously, depending on the properties of the yarn which are gettin5 g
wound. If same type of yarn (1) is used in a machine on all bobbins, then it is not
required to have different pressure settings from bobbin to bobbin. However, in
the case where different bobbins (2) are wound with yarns of different properties
(such as denier) on the same tapeline machine then different settings may be
10 required.
Pressure setting required for good winding (without side fall and better finish)
depends upon yarn properties like denier and yarn winding tension. For a single
low denier yarn (1), as a comparative measure, lower tension is required at lower
15 diameter of bobbin (because at lower diameter yarn tension is higher due to higher
angular velocity of bobbin) and higher tension at higher diameter of bobbin due
lower angular velocity of bobbin. Thus, by keeping lower tension at lower
diameter the higher tension of yarn (which results due to higher angular velocity)
gets compensated. The actual values of the required tension are known to a person
20 skilled in the art. On the contrary, if higher denier yarn is used (i.e. in case of
heavy duty take-up winders) then the higher tension is required at smaller
diameter and lower tension is required at higher bobbin diameters.
16
As discussed here, there are a number of issues addressed by the invention. First,
invention solves technical problem of winding bobbin throughout using same
tension adjusted for dancing arm, resulting higher tension during unwinding at
low bobbin sizes.
5
Second, the problem stated in above context of fabric size variation also gets
resolved because of less variation in unwinding slit film tape tension at smaller
bobbin sizes. For example, the conventional winder results in fabric width
variation of 10 to 12%, while the inventive winder bobbins resulted in fabric
10 width variation of 4 to 6%.
It is evident from the foregoing discussion that the invention has a number of
embodiments.
1. An apparatus for regulating winding tension as function of bobbin (2)
15 diameter in a slit film tape or yarn (1) winder system carrying at least one
winder, said apparatus comprising a dancing arm (3), the instantaneous
position (3F) of said dancing arm (3) and resistance R to movement of said
dancing arm (3) being variable during the yarn winding operation,
characterized in that said apparatus comprises a tension setting
20 device/means (3B) for changing said resistance 'R' of the dancing arm (3)
as a function of the bobbin (2) diameter 'D' during the winding process.
17
2. An apparatus as disclosed in embodiment 1, characterized in that said
tension setting device/means (3B) is a pressure multiplexer capable of
changing said resistance R in discrete steps or gradually.
3. An apparatus as disclosed in embodiment 2, characterized in that in the
case of the discrete-stepped pressure change, said pressure multiplexer i5 s
provided with at least two separate pressure lines (11A and 11B) and a
pressure line selection switch, wherein only one pressure line (11A or
11B) is activated at any time using said switch and the pressure is
transmitted to said dancing arm (3) for generating resistance R.
10 4. An apparatus as disclosed in any of embodiments 2 and 3, characterized in
that said pressure multiplexer is controlled with an electromechanical
control device for selecting one pressure line (11A or 11B) at a time to
connect with dancing arm (3), said electromechanical device preferably
being a pneumatic valve which is electronically controlled for being turned
15 on or switched off.
5. An apparatus as disclosed in any of embodiments 1 to 4, characterized in
that said apparatus still further comprises a man machine interface (MMI)
(8), a parent controller (9), and a winder head controller (10), wherein said
pressure multiplexer (12) is capable of selecting a pressure line (11A or
20 11B) based on the feedback from said winder head controller (10).
6. An apparatus as disclosed in any of embodiments 1 to 5, characterized in
that said MMI (8) is capable of entering desired winder machine
parameters such as the yarn denier, weight, speed, the tube outer diameter;
18
said winder head controller (10) is capable of carrying information about
cutoff bobbin size above which pressure line (11A or 11B) switching is
required, there being provided one winder head controller (10) for each
winder in the group of winders; said parent controller (9) is capable of
transferring process data such as the line speed, winding recipe, etc. fro5 m
each winder to respective winder head controllers (10).
7. An apparatus as disclosed in any of embodiments 1 to 6, characterized in
that said dancing arm has at any time an instantaneous position (3F) which
is electronically monitored.
10 8. An apparatus as disclosed in any of embodiments 1 to 7, characterized in
that said tension setting device/means is electromechanically controlled.
9. An apparatus as disclosed in any of embodiments 5 to 8, characterized in
that at least one of said winder head controllers, said parent controller, and
said MMI are connected by a communication bus.
15 10. An apparatus as disclosed in any of embodiments 6 to 9 characterised in
that said cutoff bobbin size value can be set during any stage of bobbin
winding ranging from prior to winding start to attainment of
predetermined full package size.
11. A method for regulating winding tension in a slit film tape or yarn (1) as
20 function of bobbin (2) diameter characterized in that said method
comprises the steps of:
- providing an apparatus as claimed in any one of claims 1 to 6,
19
- determining the bobbin (2) diameter at which the resistance of said
dancing arm needs to change
- dynamically changing the resistance of the dancing arm (3) during the
yarn winding process by using pneumatic or magnetic or
electromagnetic braking technology5 .
12. A method for regulating winding tension as function of bobbin diameter as
disclosed in embodiment 11, characterized in that in said step of
dynamically changing the resistance, the actual change in resistance is
effected through a pressure multiplexer in discrete steps.
10 13. A method for regulating winding tension as function of bobbin diameter as
disclosed in embodiment 12, characterized in that in said step of
dynamically changing the resistance, the actual change in resistance is
effected through a pressure multiplexer gradually.
15 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
20 scope of the invention should be determined not by the embodiments illustrated,
but by the appended claims and their legal equivalents.

We claim:
1. An apparatus for regulating winding tension as function of bobbin (2)
diameter in a slit film tape or yarn (1) winder system carrying at least one
winder, said apparatus comprising a dancing arm (3), the instantaneous
position (3F) of said dancing arm (3) and resistance R to movement of sai5 d
dancing arm (3) being variable during the yarn winding operation,
characterized in that said apparatus comprises a tension setting
device/means (3B) for changing said resistance 'R' of the dancing arm (3)
as a function of the bobbin (2) diameter 'D' during the winding process.
10 2. An apparatus as claimed in claim 1, characterized in that said tension
setting device/means (3B) is a pressure multiplexer capable of changing
said resistance R in discrete steps or gradually.
3. An apparatus as claimed in claim 2, characterized in that in the case of the
discrete-stepped pressure change, said pressure multiplexer is provided
15 with at least two separate pressure lines (11A and 11B) and a pressure line
selection switch, wherein only one pressure line (11A or 11B) is activated
at any time using said switch and the pressure is transmitted to said
dancing arm (3) for generating resistance R.
4. An apparatus as claimed in any of claims 2 and 3, characterized in that
20 said pressure multiplexer is controlled with an electromechanical control
device for selecting one pressure line (11A or 11B) at a time to connect
with dancing arm (3), said electromechanical device preferably being a
21
pneumatic valve which is electronically controlled for being turned on or
switched off.
5. An apparatus as claimed in any of claims 1 to 4, characterized in that said
apparatus still further comprises a man machine interface (MMI) (8), a
parent controller (9), and a winder head controller (10), wherein sai5 d
pressure multiplexer (12) is capable of selecting a pressure line (11A or
11B) based on the feedback from said winder head controller (10).
6. An apparatus as claimed in any of claims 1 to 5, characterized in that said
MMI (8) is capable of entering desired winder machine parameters such
10 as the yarn denier, weight, speed, the tube outer diameter; said winder
head controller (10) is capable of carrying information about cutoff bobbin
size above which pressure line (11A or 11B) switching is required, there
being provided one winder head controller (10) for each winder in the
group of winders; said parent controller (9) is capable of transferring
15 process data such as the line speed, winding recipe, etc. from each winder
to respective winder head controllers (10).
7. An apparatus as claimed in any of claims 1 to 6, characterized in that said
dancing arm has at any time an instantaneous position (3F) which is
electronically monitored.
20 8. An apparatus as claimed in any of claims 1 to 7, characterized in that said
tension setting device/means is electromechanically controlled.
22
9. An apparatus as claimed in any of claims 5 to 8, characterized in that at
least one of said winder head controllers, said parent controller, and said
MMI are connected by a communication bus.
10. An apparatus as claimed in any of claims 6 to 9 characterized in that said
cutoff bobbin size value can be set during any stage of bobbin windi5 ng
ranging from prior to winding start to attainment of predetermined full
package size.
11. A method for regulating winding tension in a slit film tape or yarn (1) as
function of bobbin (2) diameter characterized in that said method
10 comprises the steps of:
- providing an apparatus as claimed in any one of claims 1 to 6,
- determining the bobbin (2) diameter at which the resistance of said
dancing arm needs to change
- dynamically changing the resistance of the dancing arm (3) during the
15 yarn winding process by using pneumatic or magnetic or
electromagnetic braking technology.
12. A method for regulating winding tension as function of bobbin diameter as
claimed in claim 11, characterized in that in said step of dynamically
changing the resistance, the actual change in resistance is effected through
20 a pressure multiplexer in discrete steps.
13. A method for regulating winding tension as function of bobbin diameter as
claimed in claim 12, characterized in that in said step of dynamically
23
changing the resistance, the actual change in resistance is effected through
a pressure multiplexer gradually.