U.S. patent application number 11/303221 was filed with the patent office on 2007-06-21 for tension control system for converting packages of elastic thread.
This patent application is currently assigned to Kimberly-Clark Worldwide, Inc.. Invention is credited to Thomas A. Bett, Thomas Tanakon Ungpiyakul, Paul A. Weber.
Application Number | 20070138331 11/303221 |
Document ID | / |
Family ID | 37890896 |
Filed Date | 2007-06-21 |
United States Patent
Application |
20070138331 |
Kind Code |
A1 |
Bett; Thomas A. ; et
al. |
June 21, 2007 |
Tension control system for converting packages of elastic
thread
Abstract
A system and method for tension control in a thread feeding
system that provides a fast and reliable method for feeding
elastomeric thread or fiber from a package to a thread processing
system. The system includes a driven elastomeric thread package
holder. The thread feeding system also includes a variable-speed
motor configured to drive the driven elastomeric thread package
holder.
Inventors: |
Bett; Thomas A.; (Oshkosh,
WI) ; Ungpiyakul; Thomas Tanakon; (Neenah, WI)
; Weber; Paul A.; (Appleton, WI) |
Correspondence
Address: |
KIMBERLY-CLARK WORLDWIDE, INC.
401 NORTH LAKE STREET
NEENAH
WI
54956
US
|
Assignee: |
Kimberly-Clark Worldwide,
Inc.
|
Family ID: |
37890896 |
Appl. No.: |
11/303221 |
Filed: |
December 15, 2005 |
Current U.S.
Class: |
242/418.1 ;
242/420.6 |
Current CPC
Class: |
B65H 2701/31 20130101;
B65H 59/04 20130101 |
Class at
Publication: |
242/418.1 ;
242/420.6 |
International
Class: |
B65H 59/04 20060101
B65H059/04 |
Claims
1) A thread feeding system comprising: guide rolls configured to
guide an elastomeric thread through a thread path of the thread
feeding system; a driven elastomeric thread package holder; a
variable-speed motor configured to drive the driven elastomeric
thread package holder; a first tension sensor configured to
determine the tension on the thread; and a first tension controller
device configured to control a speed of the variable-speed
motor.
2) The thread feeding system of claim 1, wherein the speed of the
variable-speed motor is maintained within a first predetermined
range of thread tension values by the tension controller
device.
3) The thread feeding system of claim 1 further comprising guide
rolls and a tension sensor, wherein a wrap angle of the thread
around the tension sensor is in the range between 5 and 210
degrees.
4) The thread feeding system of claim 1, wherein the driven
elastomeric thread package holder is adapted to contact a core of
an elastomeric thread package.
5) The thread feeding system of claim 1, wherein the driven
elastomeric thread package holder is adapted to contact a
circumference of an elastomeric thread package.
6) The thread feeding system of claim 1 further comprising a
plurality of driven fiber package holders.
7) The thread feeding system of claim 1 further comprising at least
one guide located less than 0.5 meter from the driven package
holder.
8) A method for controlling elastomeric thread tension in a thread
feeding system for a manufacturing system, comprising measuring a
thread tension of a moving elastomeric thread; determining whether
the moving thread has a tension that is out of range relative to a
predetermined tension value; controlling the speed of a driven
elastomeric thread package holder; and delivering the thread to a
desired location in the manufacturing system.
9) The method of claim 8, further comprising determining whether an
average tension for the moving thread is out of range relative to
the predetermined tension value for the thread.
10) The method of claim 8, further comprising setting an alarm when
the thread tension is at a level indicating at least one of broken,
not moving and thread out of range tension level.
11) The thread feeding system of claim 8 further comprising at
least one guide located less than 0.50 meter from the driven
package holder.
12) The method of claim 8, wherein the driven elastomeric thread
package holder is adapted to contact a circumference of an
elastomeric thread package.
13) The method of claim 8, wherein the driven elastomeric thread
package holder is adapted to contact a core of an elastomeric
thread package.
14) The method of claim 8 further comprising a plurality of driven
fiber package holders.
15) The method of claim 11, wherein the elastomeric thread package
is an as-spun elastomeric thread package.
16) A thread feeding system comprising: guide rolls configured to
guide an elastomeric thread through a thread path of the thread
feeding system; a driven elastomeric thread package holder; a
variable-speed motor configured to drive the driven elastomeric
thread package holder; at least one guide located less than 0.5
meter from the driven package holder; a first tension sensor
configured to determine the tension on the thread; and a first
tension controller device configured to control a speed of the
variable-speed motor; wherein the speed of the variable-speed motor
is adjusted to maintain the tension on the thread within a
predetermined range of thread tension values.
17) The thread feeding system of claim 16 further comprising guide
rolls and a tension sensor, wherein a wrap angle of the thread
around the tension sensor is in the range between about 5 and about
210 degrees.
18) The thread feeding system of claim 16, wherein the driven
elastomeric thread package holder is adapted to contact a core of
an elastomeric thread package.
19) The thread feeding system of claim 16, wherein the driven
elastomeric thread package holder is adapted to contact a
circumference of an elastomeric thread package.
20) The thread feeding system of claim 16 further comprising a
plurality of driven fiber package holders.
Description
BACKGROUND
[0001] One common method of unwinding thread from a cylindrical
mandrel (or "package") in a manufacturing process is referred to as
over end takeoff (OETO). It should be noted that the terms "thread"
or "fiber" are used interchangeably throughout this document. One
issue common with OETO is unacceptable variations in threadline
tension. These variations in threadline tension may result in
excess utilization of thread, breakage of the thread in the
manufacturing process, or poor product quality. Further, most
thread vendors' product OETO thread packages by rewinding an as
spun roll. This step incurs additional processing and cost.
[0002] Another common method of unwinding thread from a cylindrical
mandrel (or "package") in manufacturing processes is referred to as
"rolling takeoff" which works in a draft mode or draw. This method
also may include unacceptable variations in threadline tension
resulting in many of the same issues described above.
[0003] The aforementioned problems make the processing of
elastomeric threads problematic. Furthermore some applications
(e.g., manufacturing of diapers and other personal care products)
require the use of as-spun thread or fiber that is substantially
finish-free. Therefore, a fast and reliable method of unwinding and
feeding elastomeric thread from a package to a thread processing
system is still needed in the art.
SUMMARY OF THE INVENTION
[0004] The present invention is a system, apparatus and method for
tension control in a thread feeding system that provides a fast and
reliable method for feeding elastomeric thread or fiber from a
package to a thread processing system. One version of the present
invention includes a thread feeding system including guide rolls
configured to guide an elastomeric thread through a thread path of
the thread feeding system and a driven elastomeric thread package
holder. The thread feeding system also includes a variable-speed
motor configured to drive the driven elastomeric thread package
holder and a first-tension sensor configured to determine the
tension on the thread. The thread feeding system also includes a
first tension controller device configured to control a speed of
the variable-speed motor.
[0005] Another version of the present invention includes a method
for controlling elastomeric thread tension in a thread feeding
system for a manufacturing system. The method includes measuring a
thread tension of a moving elastomeric thread and determining
whether the moving thread has a tension that is out of range
relative to a predetermined tension value. The method also includes
controlling the speed of a driven elastomeric thread package holder
and delivering the thread to a desired location in the
manufacturing system.
[0006] Finally, another version of the present invention includes a
thread feeding system including guide rolls configured to guide an
elastomeric thread through a thread path of the thread feeding
system. The system also includes a driven elastomeric thread
package holder and a variable-speed motor configured to drive the
driven elastomeric thread package holder. The system includes at
least one guide located less than 0.5 meter from the driven package
holder; a first tension sensor configured to determine the tension
on the thread; and a first tension controller device configured to
control a speed of the variable-speed motor. Further, the speed of
the variable-speed motor is adjusted to maintain the tension on the
thread within a predetermined range of thread tension values.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The foregoing and other features and aspects of the present
invention and the manner of attaining them will become more
apparent, and the invention itself will be better understood by
reference to the following description, appended claims and
accompanying drawings, where:
[0008] FIG. 1 illustrates a plan view of an embodiment of a thread
feeding system; and
[0009] FIG. 2 illustrates a plan view of a second embodiment of a
thread feeding system which feeds multiple threads.
DETAILED DESCRIPTION OF THE INVENTION
[0010] FIG. 1 illustrates a thread feeding system (40). As shown in
FIG. 1, a package (10) is held by a driven elastomeric thread
package holder (12). The package holder (12) is sized such that the
package (10) may be placed on the holder (12). The package holder
may be adapted to contact a core of an elastomeric thread package.
Alternatively, the package holder may be adapted to contact the
circumference of the elastomeric thread package. The thread or
fiber (11) is then directed, in sequence, through a static guide
(14) having a substantially circular orifice; a tension device (16)
around which the fiber may be wrapped; and a driven take-up roll or
set of rolls (18). The static guide (14) is typically an orifice
whose inner surface can be a highly polished ceramic material. Such
a surface can provide excellent wear resistance and low friction.
The take-up roll or rolls (18) representing that part of the
manufacturing process equipment to which the thread or fiber is
being supplied, is/are rotated at a speed relatively higher than
the elastomeric thread package holder (12), so as to provide the
desired draft.
[0011] The package holder (12) is connected to a variable-speed
motor (24). A distance (d) between the package and the first static
guide (14) may be relatively short, such as less than 1.00 meter,
or less than 0.50 meter or less than 0.25 meter. These short
distances may allow for compact thread feeding systems (40). During
run, the thread is removed from the package (10) and the driven
holder speeds up or slows down depending on the tension measured by
the tension device (16) and a predetermined range of thread tension
values. One or more additional guides (20), (22) for stabilizing
the position of the threadline may be provided along the
threadline.
[0012] The following paragraphs give exemplary details of the
operation of the drive and tension control apparatus in terms of
guides (20), (22), tension sensor (16), motion sensor (26), and
break sensor (28).
[0013] The thread feeding system (40) may be attached to a central
frame member to form a free standing process. Alternatively, the
feeding system may be integrated into a manufacturing system such
as an absorbent article manufacturing system.
[0014] Alternatively one or more portions of the feeding system
(40) may be integrated into the manufacturing system while other
portions remain free standing.
[0015] As illustrated in FIG. 1, a driven elastomeric thread
package holder (12) holds a package (10) and rotates thereby
feeding the thread off the package. After the thread comes off the
package (10), the thread may be directed by static guides (14). If
multiple threads are being used, a static guide (14) may be
provided for each thread. Alternatively, if two packages (10) are
held by one package holder (12), the two strands may pass through a
single static guide (14), thereby treating the two or more strands
as a single strand. Static guide (14) is preferably an orifice
through which the thread passes. The static guides (14) may be
substantially circular orifices. However, static guides (14) are
not limited to having a circular orifice for directing the thread.
As can be appreciated, alternative embodiments may use any known or
appropriate guide device for directing the thread.
[0016] Thread feeding system (40) includes a driven package holder
(12) and a tension control device (30) that is used to increment,
maintain or decrease the amount of tension in the elastomeric
thread. The tension controller (30) is connected to a tension
sensor (16). The tension sensor (16) determines a measure of the
tension of the thread as the thread comes off the driven package
holder (12) and generates a signal representative of that
tension.
[0017] The tension sensor (16) is positioned after the driven
package holder (12) and in the thread path. The distance the thread
travels between the driven package holder (12) and tension sensor
(16) is preferably minimized. Reducing the distance the thread
travels between driven package holder (12) and tension sensor (16)
enables the thread feeding system (40) to better account for
tension variations occurring at the point where the correction is
being made (i.e., at the driven package holder (12)). A substantial
distance between driven package holder (12) and tension sensor (16)
may add additional tension variations not seen at the driven
package holder (12).
[0018] As shown in FIG. 1, guides (14), (20) and (22) may include a
combination of static guides and captive rolling guides which
direct the thread through the feeding system (40). Alternatively,
any of the guides (14), (20), (22) may be eliminated from the
feeding system (40) if an applications performance can be improved
through the use of fewer guide rolls.
[0019] After the thread passes through the static guides (14) the
thread engages a guide roll (20) configured to direct the thread
through the thread feeding system (40). Again, if multiple threads
are being used, a guide roll (20) may be provided for each thread.
If the thread feeding system (40) is supplying multiple thread
groups to the manufacturing system, multiple thread feeding systems
(40) may be added as shown in FIG. 2.
[0020] Multiple tension sensors (16, 16') may be used to determine
a net tension value for a group of threads. Multiple break sensors
(28, 28') may be used to determine whether there is a break in any
individual thread or fiber. In addition, multiple motion sensors
(26, 26') may be added to determine whether individual threads are
moving. Non-limiting examples of tension, breakage and motion
sensors are also available from BTSR.
[0021] The tension sensor (16) may be attached to a tension
controller device (30) which may be a programmable device that
implements a tension trimming algorithm in accordance to programs
and parameters entered into the device. A non-limiting example of
such a tension controller device (30) is a Cygnus Digital tension
controller manufactured by Magnetic Power Systems, Inc., 1626
Manufacturers Drive, Fenton, Mo. Another suitable tension
controller device (30) is available from Dover Flexo Electronics,
Inc., 217 Pickering Road, Rochester, Minn. The tension controller
(30) may include, but is not limited to a digital display or
readout (32) that provides information on the controller operation
and measurements; input devices (34) such as buttons, keyboard, or
a touch panel for inputting information, and indicator lights (36);
such as light-emitting diodes, that represent the status of the
device and alarms.
[0022] FIG. 1 shows the motor (24) for the driven package holder
(12) and the connection between the motor (24) and the tension
controller device (30). Cable (38) may be used to make the
electrical connection for the control signals transmitted between
the tension controller device (30) and the variable speed motor
(24). A variety of electrical interfaces including but not limited
to, serial bus, parallel bus, PMCIA bus and USB bus interfaces may
be transmitted using cable (38). Signals from the tension
controller device (30) are used to control the speed of the
variable speed motor (24).
[0023] The variable-speed motor (24) may include a drive shaft
attached to a package holder (12). The motor (24) is a variable
speed motor. This is in contrast to the constant speed motors
typically used in background art unwinding devices/thread feeding
systems. The thread feeding system, including the tension
controller device (30) provided after driven package holder (12),
monitors the tension of the thread coming off the driven package
holder (12) and alters the speed of motor (24) to control the
tension of the thread (11).
[0024] Variable-speed motor drive systems are well known, as are
the corresponding control systems. It should be understood that the
thread speed in the present invention may be driven and controlled
by any suitable or otherwise appropriate drive and control system.
The variable speed motor (24) may be a servomotor and the tension
controller device (30) may be a servo driver having a built in PID
controller. One vendor providing such controllers is Emerson
Control Techniques, 12005 Technology Drive, Eden Prairie, Minn.
55344. A non-limiting example of such a variable speed motor is the
Emerson Control Techniques Unimotor Series, Model 75EZB301CACM,
which may use an Emerson Control Techniques Undrive Series, Model
SP1201, Drive Controller. This variable speed motor drive system
includes an internal tension PID so that an external PLC or other
motor controller is not required. The system has an approximate
update time of 250 microsecond (.mu.s) on the tension input.
Another example of such a system is an Allen-Bradley ControlLogix
controller, SERCOS interface module, Allen-Bradley servo drives and
MPL-A310F motor.
[0025] In one embodiment, tension sensor (16) is a strain gauge
load cell sensor that provides an output voltage signal to tension
controller device (30) that is representative of thread tension.
One suitable strain gage sensor is a MagPower CL1-5 or LC-5000
tension sensor (16) available from Magnetic Power Systems, Inc.,
1626 Manufacturers Drive, Fenton, Mo. As can be appreciated, the
thread feeding system (40) may include any sensor suitable to
provide an output signal representative of thread tension. As yet
another alternative, a displacement LVDT load cell type sensor may
also be used.
[0026] Tension sensor (16) may be calibrated to have a tension
detection range between 0 grams and 500 grams. Alternatively,
tension sensor (16) may be calibrated to have a range of detection
between 0 grams and 1000 grams. As can be appreciated, tension
sensor (16) may be calibrated to have a variety of ranges of
tension detection depending on the application. In addition,
alternative embodiments may utilize additional tension sensors
variously located throughout the thread feeding system. However, as
can be appreciated, these tension sensors may include a variety of
characteristics and calibrations.
[0027] The tension sensor (16) may utilize a variety of voltage,
current, magnetic or other representative signals and a variety of
ranges for these representative signals. More specifically, the
tension sensor (16) may supplies an output signal in the form of a
voltage to the tension controller device (30) that is dependent on
the thread tension. Tension sensor (16) may provide an output
voltage signal ranging from 0 volts to 10 volts that is
representative of thread tension.
[0028] Guide rolls (42), (44) and tension sensor (16) define a wrap
angle (.theta.) in the range of 5 to 210 degrees of circumference
for the thread around the tension sensor (16). Preferably, the
thread is wrapped over the range of 45 degrees to 190 degrees.
Directing the thread through tension sensor (16) at the wrap angle
(.theta.) enables the tension sensor (16) to more easily be
calibrated based on the type of thread and the number of threads
being used. A predetermined wrap angle (.theta.), at a
predetermined tension, will provide a resultant force on the
tension sensor (16).
[0029] This resultant force is detected by tension sensor (16) and
converted into an output signal that can be recognized by tension
controller device (30).
[0030] In one embodiment, a user enters directly into tension
controller device (30) a desired tension setpoint that is to be
maintained for the thread. The tension controller device (30)
receives input signals from the tension sensor (16) representative
of the thread tension. Tension controller device (30) uses these
input signals to determine whether the tension level of the thread
coming off driven package holder (12) can be maintained because it
is at set point, or whether the tension needs to be increased or
decreased.
[0031] The tension controller device (30) will change the speed of
the variable speed motor (24) in order to minimize the difference
between the thread tension and the set point.
[0032] If the tension controller device (30) determines that the
thread tension after the driven package holder (12) is too high,
the tension controller device (30) will increase the speed of motor
(24). Alternatively, if the tension controller device (30)
determines that the thread tension (12) is too low, the tension
controller device (30) will decrease the speed of motor (24).
[0033] As described above, thread feeding system (40) may be
configured to look at a signal from the tension sensor (16) in
determining the appropriate speed for motor (24). Further, thread
feeding system (40) may include multiple sensors positioned
throughout the system that determine the appropriate speed of motor
(24).
[0034] In the configuration shown in FIG. 1, the control of the
speed of motor (24) may be is based solely on tension feedback from
an individual tension sensor (16). In this case, the changes in
speed may likely occur frequently and in large
increments/decrements. An advantage that the present system
utilizing a driven package holder (12) may have over systems
utilizing OETO is that large decrements in the speed of the motor
(12) will not cause slack in the thread (11). In the OETO system, a
large decrement in the speed of a motor may cause slack in the
thread which may lead to subsequent slippage or tangling, and
therefore breakage of the thread. This characteristic of the
present system may eliminate the need for any pretensioners in the
system.
[0035] FIG. 2 illustrates a thread feeding system (40) designed to
feed a plurality of threads, specifically two threads (11), (11'),
into the manufacturing system. Specifically, FIG. 2 illustrates a
plurality of driven package holders (12), (12') and a plurality of
tension sensors (16), (16'). In FIG. 2 element numbers followed by
a prime (') indicate duplicative elements. Duplicative elements,
such as motor (12) and motor (12') may be identical; alternatively,
duplicative element may be substantially similar. Tension
controller devices (30) and (30') may be programmed separately,
such that they independently control threads (11) and (11').
Alternatively, tension controller devices (30) and (30') may
include additional programming such that the two devices control
the tension of threads (11) and (11') together. For example, the
controller devices may control the tension of each individual
thread within range X, and control the combined tension of the
thread within a second range Y, wherein range X is greater than
range Y. This may allow for smother operation of the combined
process.
[0036] The foregoing description of the present invention provides
illustration and description, but is not intended to be exhaustive
or to limit the invention to the precise form disclosed.
Modifications and variations are possible in light of the above
teachings or may be acquired from practice of the invention. The
scope of the invention is defined by the claims and their
equivalents.
[0037] The foregoing figures (FIG.) show particular unwinder
systems used to feed elastomeric threads to a thread processing
system. However, it should be understood that the present invention
is not limited to the configuration of the unwinder systems shown.
Alternative unwinder systems within the scope of the present
invention may vary from the unwinder systems shown in a variety of
ways not limited to but at least including: (1) the number of
threads being fed; (2) types of packages supported; (3) positioning
and use of guide members; and (4) number and type of drive systems.
In particular, the present invention is suitable for use with any
unwinder system where it would be desirable to monitor and control
the tension of elastomeric or other types of thread in order to
minimize tension variations in the thread from being introduced
into a thread processing system.
[0038] Further, the written description of exemplary embodiments
discusses the applicability of the present invention for providing
elastomeric thread to a thread processing system in the form of a
diaper manufacturing system. In particular, the application is
preferably directed at the task of supplying elastomeric thread to
be used for the elastic band features present near the open end of
the legs of the diaper. While the present invention is shown in a
diaper manufacturing environment, such illustration is not intended
to be limiting and is included for exemplary purposes only. It will
be understood by those skilled in the art after reading the
description that the present invention is equally suitable for use
for any other manufacturing process that utilizes an elastomeric
thread.
[0039] Further, though only a few exemplary embodiments of the
present invention have been described in detail in this disclosure,
those skilled in the art who review this disclosure will readily
appreciate that many modifications are possible in these
embodiments (e.g. types of rack systems, guide systems, drive
systems, and control systems; sizes, structures, shapes and
proportions of the various elements and mounting arrangements; and
use of materials in terms of combinations and shapes) without
materially departing from the novel teachings and advantages of the
present invention.
[0040] Furthermore, the order or sequence of any process or method
steps may be varied or re-sequenced according to alternative
embodiments. Other substitutions, modifications, changes and
omissions may be made in the design, operating configuration and
arrangement of the preferred and other exemplary embodiments
without departing from the spirit of the inventions as expressed
herein.
* * * * *