GB2410244A

GB2410244A - Drive system for a webbing winding apparatus

Info

Publication number: GB2410244A
Application number: GB0401652A
Authority: GB
Inventors: Richard John Truscott
Original assignee: PFE International Ltd
Current assignee: PFE International Ltd
Priority date: 2004-01-26
Filing date: 2004-01-26
Publication date: 2005-07-27
Anticipated expiration: 2024-01-26
Also published as: GB0401652D0; GB2410244B

Abstract

A drive system for a webbing winding apparatus comprises at least two spaced rollers 4a,5 which are driven by a geared arrangement 20 so as to as to move the webbing 1, the gear transmission ratio being controlled so as to maintain the tension in the webbing. The gear arrangement may comprise an epicyclic gear set or an in-line gear set. The drive system is particularly suited to winding and unwinding continuous webbing, such as paper, onto and from the spindle of a wound roll.

Description

24 1 0244 Drive System for Winding Tension Control

Description

The present invention relates to a drive system for apparatus for winding continuous webbing, such as paper, onto a spindle to form a wound roll of the webbing, or for unwinding such webbing from a roll, and particularly to a tension control mechanism for such a drive system.

When webbing such as paper is wound to form a paper roll it is necessary to maintain a constant speed for the surface of the paper but also to apply a tension to the webbing to ensure smooth and even winding. This is often done with a dancer arm which is a pivoted arm, spring biased toward the webbing, which rests against the webbing to apply a tension.

This is relatively complex to set up and load. It is also possible to apply tension by driving two spaced rollers in a cooperating manner such as a master-slave relation so that the lead roller effectively drags the slave roller and thus creates tension in the webbing. This is relatively inefficient in use of energy since the motors are effectively working against each other paper rolls of this type are typically very large since the width would typically be twice the width of an A4 sheet of paper, and thus large amounts of energy are involved.

In any case it is also desirable to apply a relatively high tension at the beginning of a winding operation, i.e. on the inside of the roll and to reduce the tension gradually as the thickness of the roll increases. If this procedure is not followed, particularly when the webbing is paper, then there is a tendency for the webbing already wound onto the roll to be squeezed and layers will not be accurately in line in the - 1 i finished product. Such a result is evidently undesirable.

According to the present invention there is provided a drive system for a webbing winding apparatus comprising: at least two spaced winding drive rollers for the webbing, and means for driving the rollers to move the webbing, wherein the driving means comprises a gear arrangement, and means for controlling the gear transmission ratio to control the tension in the webbing.

The gear arrangement may comprise a driven (input) gear, a driving (output) gear and a retaining gear and the force applied to the retaining gear is controlled to adjust the gear transmission ratio. An epicyclic gear arrangement may be used, or an in-line gear set.

According to one embodiment the control means for the gear transmission ratio comprises a hydraulic piston-cylinder arrangement.

The piston-cylinder arrangement preferably controls the position of the ring gear in an epicyclic arrangement or the idle gear of an in-line gear set. This makes the gear arrangement particularly sensitive and allows small adjustments to the webbing tension to be made.

Preferably there is also provided means for compensating for webbing extension which comprises means for sensing a limit of extension of the piston in one direction and in response thereto activating a compensating drive motor to drive the gear arrangement a compensating amount in the opposite direction. l

For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made to the accompanying drawings, in which: S Figure 1 is an overall perspective view of apparatus for winding continuous webbing on to a rolls Figure 2 is an enlargement of part of the apparatus of figure 1 showing more detail; Figure 3 is a schematic drawing showing how the continuous Figure 4 is a cross-sectional view of the device of figure 2; l5 Figure 5 is a cross-sectional view of the one embodiment of a gear arrangement suitable for the device of figure 4.

Figure 6 is a cross-sectional view of a second embodiment of a gear arrangement suitable for the device of figure 4.

In Figure 1 a continuous webbing 1, typically of paper, is shown being wound onto a spindle 2, in the direction of arrow 3 to form a roll 6. As the continuous webbing 1 is wound onto the spindle 2 it is kept under tension T by a pair of drive rollers 4a and 4b and a control roller 5. The webbing 1 passes through the nip of the rollers 4a and 4b and passes under the roller 5 which abuts the outside layer of the paper roll 6.

The roller 4a is mounted on a spindle 9 for rotation about the central longitudinal axis of the spindle. Likewise roller is mounted for rotation on spindle 17.

Tension T in the webbing is controlled by an arrangement 7, including a hydraulic piston-cylinder 8 and a gear arrangement in housing 20 acting on the spindle 9 of roller 4a.

The arrangement 7 controls the drive speed of the spindle 9 and thus of the roller 4a. The spindle 9 is rotated in a direction indicated by the arrow 10 by means of a pulley wheel 11 driven by a belt 12 which in turn is driven by a pulley wheel 13 connected to a motor 14. The motor 14 also drives belt 15 lO which drives pulley 16 to rotate the spindle 17 of the control roller 5. The pulley wheels 11 and 16 for rollers 4a and 5 respectively are driven synchronously and at the same speed.

The relative rotation speeds of the respective rollers 4a and are controlled by the arrangement 7 and optionally by a gearing arrangement in box 18 (to compensate, for example, for different sized rollers being used).

The control arrangement 7 is shown in more detail in figure 2. The pistoncylinder 8 may be hydraulically or air controlled and controls the position of an arm 19 which in turn controls the setting of an epicyclic gear arrangement housed in gear box 20. This is a well-known form of gear arrangement typically comprising a central "sun" gear, and at least one orbital or planetary gear surrounded by a ring gear. The pulley wheel 11 typically drives the central sun gear whilst the planetary gears drive the spindle 9 and hence also roller 4a at a relative speed dependent upon the gear transmission ratio. The arm 19 controls the position of the ring gear (see Figure 4) and holds it in place so as to retain the planetary gears around the sun gear. Typically the sun gear rotates in the same direction as the orbital direction of the planetary gears so that, as shown, when the pulley gear 11 rotates in the direction of arrow 21 then the spindle 9 driving roller 4a also rotates in the same direction (clockwise) as shown by arrow 10.

The gearing arrangement is shown in more detail in Figures 5 and 6.

Figure 3 is a schematic showing the tension T in the webbing 1 held between the rollers 4a and 4b at one end and the control roller 5 together with the paper roll 6 at the other end. This tension is dependent upon the relative rotation speeds of the two sets of rollers, and this on the gear transmission ratio of each of the epicyclic gear arrangement in box 20 and any gear arrangement in box 18.

Figure 4 shows the arrangement in more detail in cross section. Figure 4 also shows an additional paper stretch compensating unit 23 which comprises a motor 24 driving an elongate arm 25 arranged to engage the ring gear 26. This arrangement periodically operates to compensate for stretching of the paper as it is being wound on the roll. Periodically the stretching causes the piston-cylinder 8 to be extended to the limit of its stroke. This is detected when the arm 19 pivots to the position of the sensor 27. If the sensor detects the arm at this position it activates the motor 24 to drive the ring gear 26 so that the epicyclic gear arrangement is reset back to its central position, detected by the central sensor 28. Similarly if the piston of the piston-cylinder 8 reaches its minimum stroke this is detected when arm 19 reaches the position of the lower sensor 29 which again activates the motor 24 to drive the ring gear 26 back into its neutral position detected by sensor 28.

Figures 5 and 6 show cross-sectional views of two alternative gear arrangements which could be used within the housing 20 of control arrangement 7. In Figure 5 a traditional sun and planet type epicyclic gear unit is shown whereas Figure 6 shows an in-line spur gear unit.

In Figure 5 an input shaft 40, typically driven by pulley wheel 11 in figure 1 is fixed to the central sun gear 38, and an output shaft, typically spindle 9, is attached to the planetary gears 36, or more accurately to a spider 37 holding the planetary gears 36 in relative juxtaposition. The ring gear 26 surrounds the sun 38 and planetary 36 gears and keeps them together, and interacts with a control gear 25. As is known with epicyclic gear units, clockwise rotation of the input shaft 27, which causes clockwise rotation of the sun gear 28 at the same rate of rotation, will in turn cause clockwise rotation of the planetary gears 36 and cause the output shaft 9 to rotate at a rotation speed relative to the input speed dependent upon the gear transmission ratio. The transmission ratio depends upon the relative sizes of the gear parts, on the tooth spacing and on whether the ring gear 26 is moved or is stationery which depends on the setting of the hydraulic piston-cylinder 8.

The same effect is achieved by the in-line spur gear unit shown in Figure 6 where the input shaft 40 is integral with an input gear 31 and the output shaft 9 is integral with the output in-line gear 32, with the idle gear 30 and the control gear 25 all being mounted in the housing 20.

The tension in the web 1 is determined by the difference in the speed at which the two rollers 4a and 5 are driven and thus effectively equates to the force being applied by the hydraulic piston-cylinder 8 to the ring gear, i.e. to the body of the epicyclic gearbox. So, by controlling the force applied by the hydraulic piston-cylinder 8, the tension in the web is regulated.

The paper roll 6 itself and its spindle 2 is usually passive and is generally driven only by the friction of the winding roller 5.

Unwinding and winding attract essentially the same principles. l

Claims

Claims 1. A drive system for a webbing winding apparatus comprising: at

least two spaced winding drive rollers (4a, 5), and means for driving the rollers (4a, 5) to move the webbing (1), wherein the driving means comprises a gear arrangement (20), and means for controlling the gear transmission ratio of the arrangement to control the tension in the webbing (1).
2. A drive system according to claim 1 wherein the gear arrangement (20) comprises an input gear (38:31), an output gear (36:32) and a retaining gear (26:30).
3. A drive system according to claim 1 or 2 wherein the means for controlling the gear transmission ratio comprises a piston- cylinder arrangement (8).
4. A drive system according to any one of the preceding claims wherein the gear arrangement is an epicyclic gear set comprising a sun gear (38), at least one planetary gear (36) and a ring gear (26).
5. A drive system according to claim 4 wherein the driving means is connected to drive the sun gear (38) and the planetary gear (36) is connected to drive one of the drive rollers (4a).
6. A drive system according to claim 4 or 5 wherein the means for controlling the gear transmission ratio comprises means for controlling the position of the ring gear (26).
7. A drive system according to claim 1, 2 or 3 wherein the gear arrangement is an in-line gear set.
8. A drive system according to any one of the preceding claims further comprising means (23) for compensating for webbing extension.
9. A drive system according to claim 8 wherein the compensating means (23) comprises means (27, 29) for sensing a limit of extension in one direction and in response thereto activating a compensating drive motor (24) to drive the gear arrangement (20) a compensating amount in the opposite direction.
lO 10. A drive system according to claim 9 when appended to claim 3 wherein the sensed limit of extension is the limit of extension of the piston of the piston-cylinder arrangement (8).
11. A drive system substantially as hereinbefore described with reference to figures 1, 2, 3 and 4 in combination with either figure 5 or figure 6.