US20240002185A1

US20240002185A1 - Electronic Nip Adjustment and Pressure Measurement on Pull Station

Info

Publication number: US20240002185A1
Application number: US18/200,849
Authority: US
Inventors: Jamie Heroux; Dwight Fameree
Original assignee: Paper Converting Machine Co
Current assignee: BW Converting Inc
Priority date: 2022-06-30
Filing date: 2023-05-23
Publication date: 2024-01-04
Also published as: EP4536574A1; MX2024015000A; WO2024005995A1

Abstract

A pull station has top and bottom continuous loops with the top continuous loop disposed on a frame and movable relative to the bottom continuous loop with a frame actuator connected with the frame. The frame actuator has a sensor for sensing position. A stop, adjustable with a stop actuator and having a load sensor, is operatively engageable with the frame and prevents movement of the top continuous loop toward the bottom continuous loop. A control determines a distance between the top and bottom continuous loops based upon the actuator position sensor; determines a force imparted to webs based on the stop load sensor, the weight of the frame and the top continuous loop, and a force imparted to the top continuous loop by the frame actuator as the webs are conveyed in the pull station; and controls the pull station based upon the distance and/or force measurements.

Description

RELATED APPLICATION DATA

This application claims priority benefit to U.S. provisional application Ser. No. 63/357,088, filed Jun. 30, 2022, the disclosure of which is incorporated by reference herein.

BACKGROUND

The disclosure is directed to an electronic nip adjustment for a pull station used in connection with a converting line. In particular, the pull station is used for processing multiple webs of material that are arranged in a vertically stacked arrangement. The pull station conveys the vertically stacked arrangement of webs from an entrance of the pull station through a discharge of the pull station.
In the current state of the art, initial setup and adjustment of a pull station for each product substrate, sheet count, stack height, and (if applicable) liquid combination is an iterative process performed manually from within the line's protective guarding, with the line stopped each time an adjustment is needed. In the current state of the art, the setting of a pull station for each product combination can be saved in a recipe or product process, but the saved value is a number read from a scale, counter, or the like which must be returned to manually. In the current state of the art, the force applied to the stack of webs is unknown, as is the extent to which the force applied to the stack of webs is in excess of that needed to maintain control of the stack of webs and/or sufficient to cause liquid to be wrung from the stack of webs. Making reference to FIG. 1A and 1B, generally speaking, in the converting line 10, the webs are unwound on an unwind station 12 and directed to a folding station 14. Depending upon the product format, the folding station 14 folds the webs W as needed and arranges them in an overlapping format to form a ribbon of webs that are arranged in a vertically stacked arrangement. The overlapping format may include any number of formats of folding, including C-folding, V-folding, W-folding and Z-Folding. A lotion may be injected onto each of the webs or into the ribbon of webs at the folding station 14. The ribbon of webs W is then introduced into the pull station 16 before entering into a cutting and stacking station 18. The pull station 16 is integral to the converting line in drawing the webs of material from the unwind station 12 and through the folding station 14 and to the cutting and stacking station 18.
The disclosure is directed to maximizing the efficiency of the pull station and the converting line, in general. In particular, the disclosure is directed to a control for controlling the pull station which enables the pull station to draw the webs from the unwind station without significantly altering the characteristics of the webs. For instance, in the fold station, a lotion or liquid may be applied to the webs or to the ribbon of webs. Accordingly, the control for controlling the pull station as described herein enables the ribbon of webs to be drawn through the converting line in an efficient manner that maintains the caliper of the respective webs and a required amount of liquid in the substrate.
As will be described in greater detail below, the control controls the position of a top continuous loop of the pull station relative to a bottom continuous loop of the pull station so as to maintain a desired force or pressure on the ribbon of webs as the ribbon is conveyed from an entrance of the pull station to the discharge of the pull station. The control also allows an adjustment to set the minimum distance between the top continuous loop and the bottom continuous loop for each specific product format processed on the converting line, thus allowing automatic set up of the pull station depending upon the product format and manufacturing processing requirements of the product. Additionally, as will be described in greater detail below, the control system allows for speed measurements to determine whether the ribbon is slipping as it is being conveyed from the entrance of the pull station to the discharge of the pull station. To the extent the ribbon is determined to be slipping, the force applied to the ribbon vis-à-vis the top continuous loop may be increased to eliminate the slipping condition while maintaining the required amount of liquid in the substrate.

DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic block diagram of a converting line using a pull station.

FIG. 1B is an operator side view of a folding station, the pull station, and cutting and stacking stations of the converting line.

FIG. 2 is an operator side perspective view of a pull station of a converting line.

FIG. 3 is a drive side perspective view of the pull station of FIG. 2 .

FIG. 4 is a partial, enlarged, operator side, perspective view of the pull station of FIG. 2 showing additional detail of a top continuous loop, a frame supporting the top continuous loop, and a frame actuator for positioning the frame and the top continuous loop.

FIG. 5 is another partial, enlarged, operator side, perspective view of the pull station of FIG. 2 showing additional detail of the top continuous loop, the top frame and the frame actuator.

FIG. 6 is a partial, front, operator side view of the pull station of FIG. 2 .

FIG. 7 is a partial, discharge end view of the pull station of FIG. 2 showing the frame and the top continuous loop in a position away from the bottom continuous loop.

FIG. 8 is a partial, discharge end view of the pull station of FIG. 2 showing the frame and the top continuous loop in a position toward the bottom continuous loop with a ribbon of webs between the top continuous loop and the bottom continuous loop.

DETAILED DESCRIPTION

FIGS. 2-8 show the general structure of the pull station 16. The pull station 16 comprises a structural framework 20 which supports the various components of the pull station. The pull station 16 comprises a top continuous loop 22 and a bottom continuous loop 24 that cooperate to draw the ribbon of webs W from an entrance 26 of the pull station to a discharge 28 of the pull station. In general, the pull station draws the ribbon of webs W through the folding and unwind stations of the converting line and to the cutting and stacking station. The top continuous loop 22 and the bottom continuous loop 24 comprise one or more belts which define surfaces between the entrance 26 and the discharge 28 of the pull station that are arranged generally parallel to each other and spaced apart generally vertically based upon a height of the ribbon of webs W to be conveyed through the pull station. Accordingly, the top continuous loop 22 and bottom continuous loop 24 are generally parallel to each other from the entrance 26 of the pull station to the discharge 28 of the pull station. As shown in FIG. 3 , the top continuous loop and bottom continuous loop are driven by a transmission which includes a belt drive system 30 and motor 32. In particular, as shown in FIG. 3 , the motor 32 drives a main belt 34 that engages a first pulley 36 on a drive shaft 38 of the bottom continuous loop 24 for movement of the bottom continuous loop. An auxiliary belt 40 extends between a second pulley 42 on the bottom continuous loop drive shaft 38 and a pulley 44 on a drive shaft 46 of the top continuous loop 22. Thus, the belt drive system 30 allows for synchronized motion of the top and bottom continuous loops 22,24 with one motor 32. It is also possible to have the top continuous loop and bottom continuous loop driven by separate drive systems and separate motors.
The top continuous loop 22 is supported by a frame 50. The frame 50 is movable relative to the structural framework 20 of the pull station 16 so as to allow the top continuous loop 22 to move toward and away from the bottom continuous loop 24. The frame 51 supporting the bottom continuous loop 24 is stationary on the structural framework 20. As best shown in FIGS. 6-8 , the frame 50 is supported on a vertical slide 52 formed in the structural framework 20 of the pull station 16 so as to allow the frame to move upward and downward on the structural framework 20 of the pull station and move the top continuous loop 22 toward and away from the bottom continuous loop 24. To effectuate motion of the frame 50 and thus the top continuous loop 22, a frame actuator 54 is provided. In one aspect, the frame actuator 54 may comprise a pneumatic cylinder with an end effector 56 that is operatively connected to a yoke 58 extending across the frame 50. Depending upon the configuration of the frame actuator 54, the frame actuator may be configured to apply a desired amount of force on the ribbon of webs W as the ribbon is conveyed from the entrance 26 of the pull station to the discharge 28 of the pull station. In one configuration of the frame actuator 54, a pneumatic cylinder may be arranged with a pressure sufficient to apply a desired force to the ribbon of webs W. The frame actuator may also be another type of linear actuator, including a ball screw or acme lead screw driven by a motor, which may supply sufficient torque and pressure to the ribbon of webs.
The frame actuator 54 may have a position sensor 60 that is adapted and configured to sense the position of the end effector 56 of the frame actuator and thus the position of the frame and top continuous loop 22 relative to the structural framework 20 of the pull station and the bottom continuous loop 24. The output of the frame actuator position sensor 60 may be directed to a controller that will be described in greater detail below.
The pull station 16 may further include a stop 70 and a shoulder 72. The stop 70 and the shoulder 72 cooperate to set the minimum distance between the top continuous loop 22 and the bottom continuous loop 24. The stop 70 may be connected to the structural framework 20 of the pull station and the shoulder 72 may be operatively connected to or formed as part of the frame As best shown in FIGS. 3 and 7-8 , the stop 70 may be provided on the drive side of the pull station, and may comprise a stop actuator 74 for adjustably positioning the stop. As best shown in FIGS. 4, 7 and 8 , the shoulder 72 may be formed as part of the frame or operatively connected to the frame. The stop actuator 74 may adjustably position the stop 70 so the stop engages the shoulder 72 at a desired position corresponding to the minimum distance between the top continuous loop 22 and the bottom continuous loop 24 for a particular product format and product manufacturing process. The stop actuator 74 may comprise a jackscrew and motor, for example, a stepper motor. For instance, the stop actuator 74 may include a right angle head connected to the jackscrew that is driven by the motor. This allows adjustments to be made to the pull station 16 from outside the protective guarding of the converting line 10, including while the pull station is running in operation, with push button controls provided in a human machine interface (HMI) 76 for the pull station and/or converting line. This also allows for automatic control and the saving of setpoints and operating parameters for a specific product format and product manufacturing process. In FIG. 7 , the stop actuator 74 is shown in a withdrawn position and the frame 50 is shown in a withdrawn position with the top continuous loop 22 away from the bottom continuous loop 24. During operation, the frame 50 is lowered via the frame actuator 54 so the shoulder 72 of the frame engages the stop 70 and the top continuous loop 22 is spaced from the bottom continuous loop 24 at a minimum height corresponding to the desired position for the product format and product manufacturing process.
The stop 70 may include a load sensor 80. The load sensor may be a button-style load cell, for example a Honeywell Model 53. The load sensor 80 may be positioned on a distal end of the stop as shown in the drawing. Alternatively, the load sensor may be incorporated into the shoulder. The load sensor 80 may be adapted and configured to sense a load applied against the load sensor when the frame 50 engages the stop 70, for instance, when the shoulder 72 of the frame engages the stop, and more in particular, when the shoulder of the frame engages the load sensor. The stop actuator 74 may also include a position sensor 82 that is adapted and configured to sense the position of the stop actuator 74 relative to the structural framework 20 of the pull station.
The pull station may be provided with a control 90. The control 90 may include a controller 92 that includes a processor 94 with a memory 96. The frame actuator position sensor 60, the stop actuator position sensor 82, and the stop load sensor 80 may all provide inputs to the control 90 and controller 92 for generating signals for controlling the pull station. Additionally, the control 90 may include at least one speed sensor 100,102 for a respective one or both of the top and bottom continuous loops for sensing the speeds of the respective top and bottom continuous loops. The control 90 may also include a speed sensor 104 (FIG. 2 ) for determining the speed of ribbon or of the plurality of webs as they are drawn from the entrance 26 of the pull station to the discharge 28 of the pull station. As will be described in greater detail below, setpoints and operating parameters relating to the product format and product manufacturing process, as well as inputs to the controller, may be stored in the memory 96 of the controller 90 so as to facilitate set up and operation of the pull station, provide real-time dynamic control of the pull station, and data to assess the efficiency and operational characteristics of the pull station which may assist in maintenance of the pull station.
In one aspect, the controller 92 is configured to determine a distance measurement D between the top continuous loop 22 and the bottom continuous loop 24 based upon the frame actuator position sensor 60 as the plurality of webs W are conveyed from the entrance 26 of the pull station to the discharge 28 of the pull station. In another aspect, the controller 92 is configured to determine a force imparted to the plurality of webs based on the stop load sensor 80, the weight of the frame 50 and the top continuous loop 22, and a force imparted to the top continuous loop 22 by the frame actuator 54. For instance, the stop load sensor 80 may sense the amount of pressure exerted by the frame 50 via the shoulder 72 against the stop 70. The weight of the frame and top continuous loop 22 may be a constant value with the remainder of the load applied against the stop load sensor 80 being a function of the position of the end effector 56 of the frame actuator 54, and the frame 50 and top continuous loop 22, and the position of the stop actuator 74. To the extent the frame actuator 54 is configured as a pneumatic cylinder, the pressure applied to pneumatic cylinder may also be measured as an input to the controller 92, and to the extent the frame actuator is configured as a servo motor drive, the torque of the motor may also be measured as an input to the controller. To the extent the frame actuator is configured as a pneumatic cylinder, if the ribbon imparts a transient force to the top continuous loop, for example, from one or more sections of splice tape that were used to connect an expired parent roll to a new parent roll, or for example, from an unexpectedly thick web in the ribbon or an unexpectedly higher number of webs in the ribbon, the pneumatic cylinder may allow the ribbon to temporarily overcome the force of the pneumatic cylinder and temporarily move the top continuous loop away from the bottom continuous loop. To the extent the stop actuator 74 is configured as a servo motor drive, the torque of the motor may also be measured as an input to the controller 92. The controller 92 may be adapted and configured to generate signals for controlling the pull station 16 based upon the distance measurements D and inputs to the controller. This may be useful in benchmarking different substrates and web materials for optimal settings and repeatability in processing. For instance, if certain material properties of a substrate comprising the web materials W are known and/or can be predicted, for instance, from prior product manufacturing processes in the converting line 10, then initial settings of distance and force may be used to facilitate set-up, and operational parameters may be set, maintained and/or changed as necessary during processing to maximize efficiency and quality. In one example, the force applied by the top continuous loop 22 may be controlled so as to limit the amount of force to that which is necessary to prevent slipping of the ribbon while ensuring any liquid or lotion applied to the ribbon is not wrung out of the ribbon. In this respect, the speed of one or both of the top continuous loop and bottom continuous loop may be measured via the respective loop speed sensors 100,102 and compared to a ribbon speed sensor 104 to determine a relative amount of slippage. Depending upon the comparison, the position of the frame 50 may be changed with the frame actuator 54 and/or the stop actuator 74. For instance, if the comparison of the speed of one or both of the top continuous loop 22 and bottom continuous loop 24 compared to the ribbon speed determines an undesirable amount of slippage, then the frame actuator 54 and/or stop actuator 74 may be operated so as to change the position of the frame 50 and top continuous loop 22 to apply additional pressure. The frame actuator sensor 60 and the stop actuator position sensor 82 along with stop load sensor 80 may provide signals to the controller 92 that trim control signals from the controller to the frame actuator 54 and/or stop actuator 74 to change the applied pressure. Depending upon the arrangement of the stop actuator and the frame actuator, pressure and/or torque signals of the respective actuators that are directed the controller 92 may also be trimmed by signals from the frame actuator and stop actuator position sensors, and the stop load sensor.
The processor 94 and the memory 96 of the controller 92 of the pull station may be configured to store a plurality of data structures in the memory of the controller. The data structures may comprise a plurality of data items associated together as at least one of: (i) the distance measurements between the top continuous loop and the bottom continuous loop as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station, (ii) the load measurements as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station, (iii) the speed of the plurality of webs being conveyed in the pull station, (iv) the speed of the at least one of the top continuous loop and bottom continuous loop as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station, and (v) one or more characteristics representative of the plurality of webs being conveyed in the pull station. The data may be used to assess operational functionality of the pull station and the converting line in general, efficiency of the pull station, product processing relative to previous product processing in the pull station, web material conditions, and maintenance of the pull station.
Further embodiments can be envisioned by one of ordinary skill in the art after reading this disclosure. In other embodiments, combinations or sub-combinations of the above-disclosed invention can be advantageously made. The example arrangements of components are shown for purposes of illustration and it should be understood that combinations, additions, re-arrangements, and the like are contemplated in alternative embodiments of the present invention. Thus, various modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the claims and that the invention is intended to cover all modifications and equivalents within the scope of the following claims.

Claims

What is claimed is:

1. A control for controlling a pull station of a converting line wherein the pull station comprises a top continuous loop and a bottom continuous loop that are adapted to receive a plurality of webs in a vertically stacked arrangement at an entrance of the pull station and convey the vertically stacked arrangement of webs between the top and bottom continuous loops through a discharge of the pull station, the top continuous loop is disposed on a frame, the frame is adjustable such that the top continuous loop is movable toward and away from the bottom continuous loop, the control comprising:

a frame actuator adapted and configured to be operatively connected with the frame in a manner to allow the top continuous loop to be moved toward and away from the bottom continuous loop, the frame actuator having a sensor adapted and configured to sense a position of the frame actuator;

a stop adapted and configured to operatively engage the frame and prevent movement of the top continuous loop toward the bottom continuous loop, the stop being adjustable with a stop actuator, the stop having a stop load sensor adapted and configured to sense a load applied against the load sensor when the frame engages the stop; and

a controller including a processor and memory, the controller being configured to (i) determine a distance measurement between the top continuous loop and the bottom continuous loop based upon the actuator position sensor; (ii) determine a force imparted to the plurality of webs based on the stop load sensor, the weight of the frame and the continuous loop, and a force imparted to the top continuous loop by the frame actuator as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station; and (iii) generate signals for controlling the pull station based upon at least one of the distance and force measurements.

2. The control of claim 1 wherein the control is configured to store a plurality of data structures in the memory of the controller, wherein the data structures comprise a plurality of data items associated together as the distance measurements between the top continuous loop and the bottom continuous loop as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station, and a characteristic representative of the plurality of webs being conveyed in the pull station.

3. The control of claim 1 wherein the control is configured to store a plurality of data structures in the memory of the controller, wherein the data structures comprise a plurality of data items associated together as the force measurements, the distance measurements between the top continuous loop and the bottom continuous loop and a characteristic representative of the plurality of webs being conveyed in the pull station.

4. The control of claim 1 further comprising a web speed sensor adapted and configured to sense a speed of the plurality of webs being conveyed in the pull station and generate a web speed signal.

5. The control of claim 4 further comprising a speed sensor associated with at least one of the top continuous loop and the bottom continuous loop, the speed sensor being adapted and configured to generate a conveyor speed signal.

6. The control of claim 5 wherein the controller is configured to compare the speed of the plurality of webs being conveyed in the pull station with the speed of the at least one of the top continuous loop and bottom continuous loop based upon the web speed signal and the conveyor speed signal; and generate signals for controlling the pull station based upon the comparison.

7. The control of claim 6 wherein the controller is configured to send a signal to the frame actuator based on the comparison.

8. The control of claim 6 wherein the controller is configured to send a signal to the stop actuator based on the comparison.

9. The control of claim 6 wherein the control is configured to store a plurality of data structures in the memory of the controller, wherein the data structures comprise a plurality of data items associated together as the force measurements as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station, the speed of the plurality of webs being conveyed in the pull station, the speed of the at least one of the top continuous loop and bottom continuous loop as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station, the distance measurements between the top continuous loop and the bottom continuous loop as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station, and a characteristic representative of the plurality of webs being conveyed in the pull station. motor.

10. The control of claim 1 wherein the frame actuator comprises a pneumatic cylinder.

11. The control of claim 1 wherein the stop actuator comprises a linear actuator driven by a motor.

12. A method of controlling a converting line having a pull station, wherein the pull station comprises a top continuous loop and a bottom continuous loop, the top continuous loop and the bottom continuous loop are adapted to receive a plurality of webs in a vertically stacked arrangement at an entrance of the pull station and convey the stacked arrangement of webs between the top and bottom continuous loops through a discharge of the pull station, the top continuous loop being disposed on a frame, the method comprising:

providing a frame actuator operatively connected to the frame that supports the top continuous loop of the pull station;

enabling a sensor of the frame actuator to sense a position of the frame actuator;

providing a stop that is configured to engage the frame and prevent movement of the top continuous loop toward the bottom continuous loop;

providing a stop actuator that is configured to adjust the position of the stop;

enabling a stop load sensor of the stop actuator to sense a load applied against the load sensor when the frame engages the stop;

configuring a processor associated with a controller of a control of the converting line to determine a distance measurement between the top continuous loop and the bottom continuous loop based upon the actuator position sensor;

configuring the processor to determine a force imparted to the plurality of webs based on the stop load sensor, the weight of the frame and the top continuous loop, and a force imparted to the top continuous loop by the frame actuator as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station; and

enabling the controller to generate signals for controlling the pull station based upon at least one of the distance and force measurements.

13. The method of claim 12 further comprising configuring the controller to store a plurality of data structures in a memory of the controller, wherein the data structures comprise a plurality of data items associated together as the distance measurements between the top continuous loop and the bottom continuous loop as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station, and a characteristic representative of the plurality of webs being conveyed in the pull station.

14. The method of claim 12 further comprising configuring the controller to store a plurality of data structures in a memory of the controller, wherein the data structures comprise a plurality of data items associated together as the force measurements as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station, the distance measurements between the top continuous loop and the bottom continuous loop as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station, and a characteristic representative of the plurality of webs being conveyed in the pull station.

15. The method of claim 12 further comprising configuring a web speed sensor to sense a speed of the plurality of webs being conveyed in the pull station and generate a web speed signal.

16. The method of claim 15 further comprising configuring a speed sensor associated with at least one of the top continuous loop and the bottom continuous loop to sense a speed of the respective continuous loop, and generate a conveyor speed signal.

17. The method of claim 16 further comprising configuring the controller to:

compare the speed of the plurality of webs being conveyed in the pull station with the speed of the at least one of the top continuous loop and bottom continuous loop based upon the web speed signal and the conveyor speed signal; and

generate signals for controlling the pull station based upon the comparison.

18. The method of claim 17 further comprising configuring the controller to send a signal to the frame actuator based on the comparison.

19. The method of claim 17 further comprising configuring the controller to send a signal to the stop actuator based on the comparison.

20. The method of claim 17 further comprising configuring controller to store a plurality of data structures in a memory of the controller, wherein the data structures comprise a plurality of data items associated together as the force measurements as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station, the speed of the plurality of webs being conveyed in the pull station, the speed of the at least one of the top continuous loop and bottom continuous loop as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station, the distance measurements between the top continuous loop and the bottom continuous loop as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station, and a characteristic representative of the plurality of webs being conveyed in the pull station.

21. A method of controlling a converting line having a pull station, wherein the pull station comprises a top continuous loop and a bottom continuous loop, the top continuous loop and the bottom continuous loop are adapted to receive a plurality of webs in a vertically stacked arrangement at an entrance of the pull station and convey the vertically stacked arrangement of webs between the top and bottom continuous loops through a discharge of the pull station, the top continuous loop being disposed on a frame, the method comprising:

sensing a position of the frame actuator;

adjustably setting a minimum distance between the top continuous loop and the bottom continuous loop;

imparting a force to the top continuous loop with the frame actuator;

sensing a load applied by the frame to the pull station;

determining a distance measurement between the top continuous loop and the bottom continuous loop based upon the position of the frame actuator;

configuring the processor to determine a force imparted to the plurality of webs based on the load applied by the frame actuator to the pull station, the weight of the frame and the top continuous loop, and the force imparted to the top continuous loop by the frame actuator as the plurality of webs are conveyed from the entrance of the pull station to the discharge of the pull station; and

enabling the controller to generate signals for controlling the pull station based upon at least one of the measurement of the distance and the measurement of the force imparted to the plurality of webs.