GB2287242A

GB2287242A - Threading webs through web-transport machines.

Info

Publication number: GB2287242A
Application number: GB9500524A
Authority: GB
Inventors: Tad T Butterworth
Original assignee: CG Bretting Manufacturing Co Inc
Current assignee: CG Bretting Manufacturing Co Inc
Priority date: 1994-03-11
Filing date: 1995-01-11
Publication date: 1995-09-13
Also published as: ITRM950101A0; GB9500524D0; DE19505432A1; JPH07267442A; KR950031493A; ITRM950101A1

Description

11 -1 PATENTS ACT 1977 P9430GB-NFlisd

DESCRIPTION OF INVENTION

2287242 "IMPROVEMENTS IN OR RELATING TO AN AUTOMATIC WEB THREADER" THIS INVENTION relates to a web threading system, and more particularly to a web threading system for use in the field of paper converting or processing machinery. The invention is especially applicable to the type of machinery having a plurality of pairs of adjacent rolls forming nips for moving a relatively wide web, for example, or web of paper (such as, but not limited to, tissue paper) through the machine.

Prior art threading of such machines was typically accomplished by hand, in a time-consuming and sometimes hazardous manner, by attaching one corner of the web to a "thread" rope or belt on one side of the machine and then using the machine drive to "jog" the rope and web through the machine. This was normally accomplished by moving the web, typically in a bunched up form, through the rolls in the journal area on one side of the machine. With such an approach, the operator was subsequently required to jog a significant amount of the paper web through the machine to get the web smooth and centred in the nips between adjacent rolls in the machine, before the machine could be run continuously. It has been f ound that this process has become increasingly difficult as the width and length of the web increase.

The present invention seeks to overcome these difficulties by providing an automatic web threader which requires no operator contact with the web once the leading edge of web has been attached to the automatic threader, thus reducing the time and effort required to thread a web through machinery such as paper converting machinery.

According to one aspect of this invention there is provided an automatic web threading system for a web processing machine comprising a) a thread bar for holding a leading edge of a web for threading the web processing machine; b) a pair of elongate flexible elements for supporting and driving the thread bar through the machine, with one flexible element at each end of the thread bar; c) a plurality of sprockets or drive wheels positioned within the machine to guide the thread bar through the web path in the machine; d) and drive means f or moving the thread bar via the elongate flexible elements to draw the web through the machine. The web processing machine may be a paper converting machine.

The elongate flexible elements may comprise any convenient type of flexible inextensible filament members such as chains or drive belts. If chains are used, the chains pass over a plurality of sprockets positioned within the machine, whereas if belts are used the belts pass over drive wheels.

Preferably the thread bar comprises clamping means for clamping the leading edge of the web in the thread bar.

Conveniently the thread bar comprises a pair of parallel members for clamping the leading edge of the web.

Advantageously the parallel members comprise a cylinder and a generally Ushaped channel.

6 1 1 Preferably the cylinder has a diameter greater than a width of the U- shaped channel.

Advantageously the clamping means further comprises a plurality of magnets in one of the parallel members and the other of the parallel members is formed of ferromagnetic material.

Conveniently the system further comprises a resilient cord passing through the ferromagnetic YaeTaber of the thread bar to position the ferromagnetic member a predetermined distance away f rom the one member when the thread bar is in an open position.

Preferably the thread bar has first and second ends separated by an intermediate portion and the magnets are spaced closer together at the f irst and second ends than they are in the intermediate portion.

Conveniently at least part of the thread bar is mounted for pivoting movement with respect to the pair of elongate flexible elements.

Advantageously at least part of the thread bar is held in alignment with the pair of elongate flexible elements in the absence of external disturbance by a portion of the resilient cord passing through an eye extending from each end of the said part.

Preferably the portion of the resilient cord passing through each eye is secured between a pair of mounting blocks secured to the respective elongate element to maintain that portion of the cord in alignment with the elongate element in the absence of external disturbance.

Advantageously the thread bar is free to pivot out of alignment with the path of the elongate elements in the event of an obstruction causing an external disturbance to the thread bar.

Preferably the drive means comprises a clutch coupled to a main drive of the machine.

Conveniently engagement of the clutch is synchronised to a timing of the machine to avoid interference between the thread bar and parts of the machine.

Advantageously the machine is a paper converting machine.

The invention also relates to a method of threading a web through a machine of the type having a plurality of nips formed by respective pairs of closely adjacent rolls for performing operations on the web passing through the machine, the method comprising a) clamping a leading edge of a web in a thread bar located at a starting station and positioned transverse to a desired path for the web in the machine; b) opening the nips in the closely adjacent rolls in the machine by an amount sufficient to clear the thread bar; c) drawing the web along the desired path through the machine by a pair of flexible and inextensible filament members attached to the thread bar while maintaining the thread bar transverse to the desired path; d) and returning the thread bar to the starting station once the web is threaded along the desired path in the machine.

Conveniently step a) further comprises holding the leading edge of the web between a pair of parallel members.

-q a A Preferably step a) further comprises using magnetic attraction between the parallel members to clamp the leading edge of the web in the thread bar.

In one embodiment the filament members comprise roller chains, but alternatively the filament members comprise belts.

Conveniently step c) further comprises engaging a clutch coupled to a main drive of the machine to draw the web through the machine.

Preferably the clutch is synchronised to the operation of the machine to avoid interference between the thread bar and parts of the machine.

machine.

Advantageously the machine is a paper converting The invention also relates to apparatus for clamping a leading edge of a web comprising: a) a base member extending parallel to a leading edge of a web of material; b) an elongated ferromagnetic tube supported on an elastic cord a predetermined distance away from the base member; and c) a plurality of magnets carried by the base member and located to attract and retain the tube to the base member when the tube is placed near the base member such that the leading edge of the web is retained between the base member and the tube by the magnetic attraction between the magnets and the tube.

Preferably the base member has first and second ends separated by an intermediate portion and the magnets are spaced closer together at the first and second ends than they are in the intermediate portion.

In order that the invention rmay be more readily understood, and so that further features thereof may be appreciated the invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a side elevation view of one embodiment of a machine provided with an automatic web threader of the present invention, FIGURE 2 is a fragmentary end elevation view showing a thread bar useful in the web threader of Figure 1, FIGURE 3 is a section view of the thread bar and a potion of the web taken along line 3-3 of Figure 2, and FIGURE 4 is a perspective view of a portion of the mounting arrangement for the thread bar of Figures 2 and 3.

Referring now to the Figures, and most particularly to Figures 1 and 2, a machine provided with an automatic web threader 10 may be seen. The web threader 10 includes a pair of chains 12,14, with chain 12 being shown in Figure 1. The chains are located respectively on the two opposed sides of the machine. In the embodiment shown, chains 12,14 are preferably rollerchain type 40 with a 1.27 cm (0.511) pitch as is available from the Boston Gear company. Web threader 10 is preferably for use with paper converting machinery, such as a rewinder machine 16 which as shown, for example, which perforates and rewinds tissue paper into relatively long Ulogs" for later severing into individually usable rolls of tissue paper. It is to be understood that the web for machine 16 in the presently described embodiment is 167 cms (5-1/2 feet) wide and in future embodiments may be as wide as 365 cms (12 feet) in the web width dimension 17. resulting in relatively long logs.

The machine 16 includes various rolls that extend transversely across the machine. Machine 16 includes a pair of pull rolls 18,20 movable apart at least 3.81 cas (1-1/2 inches) in the direction indicated by arrow 21. when machine 16 is operating, it is to be understood that pull rolls 18, 20 are moved together forming a nip therebetween to pull the web 50 into the machine 16. In Figure 1, rolls 18,20 are shown spaced apart for web threading.

Machine 16 also includes a perforator roll 22 which the web passes after leaving the pull rolls 18,20. The perforator roll 22 co-operates with a perforator bar 24 to perforate the web 50 in a conventional manner. A synchronising roll 26 is preferably pivoted on lever arm 28 to engage the web 50 after it leaves the perforator roll 22. The synchronising roll 26 is controlled by an actuator 30, such as an air cylinder or powered lead screw to synchronise the operation of the perforator section 22,24 with the operation of a chop roll 32, since it is desirable to sever the web 50 with chop roll 32 along a line of perforations formed by the perforator section 22,24.

The web 50 passes over an idler roller 34 and around a transfer roll 36. Transfer roll 36 together with a pair of winding rolls 38,40 form a pair of winding stations for alternatively winding logs in machine 16. It is to be understood that winding rolls 38,40 are arranged together with transfer roll 36 as shown to form a pair of nips with transfer roll 36, and are arranged to move apart in the direction shown by arrows 42,44 by a distance of at least 3.81 cms (1-1/2 inches) apart to permit threading of the machine 16. Rolls 38,40 are each movable in the direction of arrows 42,44 by a pair of ball screws and an air motor, being driven by a cross shaft to maintain parallelism.

The web threader 10 includes a frame 46 through which an operator 66 can walk to attach the web 50 and to inspect the various parts of the machine 16 and threader 10. An input idler roll 48 is available to guide web 50 to the web threader 10.

Referring now also to Figure 3, a thread bar 52 is provided for holding a leading edge of web 50 for threading through the paper rewinder machine 16. Thread bar 52 has a clamping means for clamping the leading edge of the web 50 in the thread bar 52. The clamping means preferably includes a pair of co-operating parallel members 54,56 for holding the leading edge of the web 50. Member 54 is preferably an extruded aluminium channel having a U-shaped cross-section with a spacing between legs of the "U" less than the diameter of member 56. Member 56 is preferably a ferromagnetic tube or pipe. Member 54 includes a plurality of magnets 58, with each carried by a magnet mounting block 60. Each mounting block 60 is preferably secured to channel 54 by a cap screw 62. Each magnet 58 is secured to its respective mounting block 60 preferably by an anaerobic adhesive. As may be seen most clearly in Figure 3, when tube 56 is brought into close proximity to the upper region of channel 54, magnets 58 will attract tube 56 and retain it against channel 54. It is to be understood that it is preferable to have a slight clearance between magnets 58 and tube 56, such that tube 56 contacts the web 50 at the inner corners of the vertical projections of channel 54. The inner corners are preferably chamfered or rounded to R prevent severing of the web 50 by the contact between members 54 and 56. The magnets are closer together in the regions of the ends of the channel 54, and are spaced further apart in the central intermediate region.

To load the leading edge of web 50 into the thread bar 52, member 56 is moved away from member 54. Member 56 is restrained and conveniently held a fixed distance from member 54 by a 0.48 cms (3116 inch) diameter polyurethane cord 64, available from Eagle Belting Company. 1683 South Mount Prospect Road, Des Plains, Illinois 60018. It is to be understood that cord 64 is resilient and provides a support for tube 56 in the 'open" position shown in phantom in Figure 2. This "open" position for thread bar 52 provides clearance for the operator 66 to insert the web 50 between members 54,56. once web 50 is positioned between members 54 and 56, member 56 is pressed down towards member 54 against the resistance of cord 64 until member 56 is retained by magnets 58 against member 54, in the position shown in Figures 1, 2 and 3 in solid lines. At this time operator 66 can remove any excess tail material 68 to provide a "clean" leading edge for web 50. It is to be understood that a slight amount of web 50 projecting as a tail 68 will not interfere with the threading process.

Returning now again to Figure 1, thread bar 52 is supported by the chains 12,14. The thread bar extends across the machine, the axis of the thread bar being parallel with the rolls of machine 16. The chains 12,14 pass over a pair of idler sprockets 70,72. It is to be understood that sprockets 70,72 are each positioned concentric to a roll which carries the web 50 along the same path as the chain 12. The chain then passes another idler sprocket 74. As is conventional,, it has been found preferable to use a bowed or "mount Hope" roll (not shown) above idler sprocket 74 to remove wri.-.!.les int he web 50 in machine 16. Chain 12 then passes over sprockets mounted outboard of and concentric with pull rolls 18,20. Similarly, sprockets are provided to move chains 12 and 14 around the synchronising roll 26 and idler roll 34.

Transfer roll 36 has a (full diameter) vacuum valve outboard of the transfer roll, eliminating the option of using a sprocket, and consequently a track or raised circumferential lip (not shown) is provided on the vacuum valve to guide chains 12 and 14 around the vacuum boxes located at the respective ends of transfer roll 36. A sheet metal guide 76, preferably generally in the form of the letter J rotated 900 counter-clockwise is provided to ensure that chains 12,14 clear winding roll 40. An idler sprocket 78 assists the chain 12 as it exits machine 16. A drive sprocket and associated roll So provide a drive means for moving the thread bar 52 via the chains 12,14 to draw the web 50 through the machine 16. Drive sprocket and roll 80 is preferably powered from the main machine drive (not shown) via a clutch 82 (shown only schematically). In addition, a timing belt or chain 84 couples drive sprocket and roll 80 to an air motor and position indicating gear box 86. Air motor 86 may be used to drive the automatic web threader 10 until it is synchronised with the cycle of machine 16. It is to be understood that clutch 82 is preferably a single engagement position clutch that will not engage unless the thread bar 52 is positioned in synchronism with the timing of the internal operation of machine 16, most notably chop roll 32 which has a projection 88 acting as a knife blade holder. It is to be understood that projection 88 would interfere with the passage of thread bar 52 between rolls 32 and 36 if projection 88 is in the nip (as it would be for performing a cut-off operation to transfer web 50 from one of the 1 R winding rolls 38,40 to the other winding roll). The gear box portion (shown only schematically at 86) also provides information to the driving means (either the air motor or the clutch 82) to control movement of the thread bar 52 to the "home" or beginning position 90 as shown in Figure 1. In the preferred embodiment, one revolution of the output shaft of the gear box 86 corresponds to one complete cycle of the automatic web threader 10 which includes moving thread bar 52 from the home position 90 through the machine 16, and back to the home position 90.

A pair of idler rolls and sprockets 92,94 are carried by a movable frame 96 and guided by a guide shaft 98 to act as a take-up mechanism for slack in chains 12 and 14. Frame 96 is loaded by gravity to tension the chains.

Referring now to Figure 4, a perspective view of the mounting arrangement f or thread bar 52 may be seen. In Figure 4 thread bar 52 is shown in solid lines in the "closed" position and in the "open" position in phantom. Cord 64 exits the tube 56 and passes through a pivot link mounting block 100. Cord 64 then passes through a clevis block cord guide eye or extension 102, which is part of a clevis block 104. Cord 64 then enters a cord end mounting block 106. The end 108 of cord 64 is trapped between block 106 and an end cap 110. An identical end cap 112 is secured to the pivot link mounting block 100. It is to be understood that cord 64 is wedged against blocks 100,106 by end caps 112,110 respectively, to prevent movement or escape of cord 64 from blocks 100,106. Block 100 provides a pivoting mounting via bolt 113 for a threader bar pivot link 114, which is also pivoted in clevis block 104 via a pin 116. Clevis block 104 is secured rigidly to channel 54 via a pair of bolts 118,120.

Blocks 100 and 106 are mounted to chain 14 via respective roller chain attachment plates 122,124.

It is to be understood that an identical mounting arrangement shown in Figure 4 is provided at the end of thread bar 52 which is supported by chain 12.

It is to be understood that thread bar 52 is mounted so as to be able to effect a pivoting movement with respect to the pair of chains and is held in alignment with chain 14 (and 12) because of the eye in extension 102 (of the clevis block 104) through which cord 64 passes. Link 114 permits thread bar 52 to pivot as it encounters obstructions (or other disturbances external to the threader 10) in the threading process in the machine 16. once the obstruction is passed, cord 64 will realign thread bar 52 because of the action of cord 64 passing through extension 102.

It is further to be understood that it is within the scope of this invention to substitute timing belts or other similar inextensible but flexible elements or filaments for chains 12 and 14. To avoid tearing web 50, it is highly preferably to synchronise or lock the operation of the chains or belts together at each side of the web threader 10 and machine 16 to avoid skewing or pulling on one side of the web more than the other side. If desired, a means for manually advancing the chains may be provided as well, such as, for example, wrench flats on an extension of the drive roll 80.

In the preferred practice of this invention, the roller chain closely follows the normal web path through the machine 16. All roll nips in machine 16 automatically open to allow the thread bar 52 to pass during threading.

When the bar 52 and web leading edge are through the machine 16, all roll nips are closed. and the machine 16 then has a full width web centred on the rolls and is ready to run at production rates. Chop roll 32 makes the first cut and starts to run while the thread bar 52 takes the short leading section of web 50 back to the home position 90 for disposal by the operator 66. This completes the threading cycle with the thread bar 52 back at the home position or starting point 90 ready for the next time it is needed.

The invention is not to be taken as limited to all of the details thereof as described since modifications and variations thereof may be made without departing from the scope of the invention.

Claims

CLAIMS:

1. An automatic web threading system for a web processing machine comprising a) a thread bar for holding a leading edge of a web for threading the web processing machine; b) a pair of elongate flexible elements for supporting and driving the thread bar through the machine, with one flexible element at each end of the thread bar; c) a plurality of sprockets or drive wheels positioned within the machine to guide the thread bar through the web path in the machine; d) and drive means for moving the thread bar via the elongate flexible elements to draw the web through the machine.

2. A system according to Claim 1 wherein the thread bar comprises clamping means for clamping the leading edge of the web in the thread bar.

3. A system according to Claim 2 wherein the thread bar comprises a pair of parallel members for clamping the leading edge of the web.

4. A system according to Claim 3 wherein the parallel members comprise a cylinder and a generally U-shaped channel.

5. A system according to Claim 4 wherein the cylinder has a diameter greater than a width of the U-shaped channel.

6. A system according to any one of Claims 3 to 5 wherein the clamping means further comprises a plurality of magnets in one of the parallel members and the other of the parallel members is formed of ferromagnetic material.

7. A system according to Claim 6 further comprising a resilient cord passing through the ferromagnetic member of the thread bar to position the f erromagnetic member a predetermined distance away from the one member when the thread bar is in an open position.

8. A system according to Claim 6 or 7 wherein the thread bar has first and second ends separated by an intermediate portion and the magnets are spaced closer together at the first and second ends than they are in the intermediate portion.

9. A system according to any one of the preceding Claims wherein at least part of the thread bar is mounted for pivoting movement with respect to the pair of elongate flexible elements.

10. A system according to any one of the preceding Claims wherein at least part of the thread bar is held in alignment with the pair of elongate flexible elements in the absence of external disturbance by a portion of the resilient cord passing through an eye extending from each end of the said part.

11. A system according to Claim 10 wherein the portion of the resilient cord passing through each eye is secured between a pair of mounting blocks secured to the respective elongate element to maintain that portion of the cord in alignment with the elongate element in the absence of external disturbance.

12. A system according to any one of the preceding Claims wherein the thread bar is free to pivot out of alignment with the path of the elongate elements in the event of an obstruction causing an external disturbance to the thread bar.

13. A system according to any one of the preceding Claims wherein the drive means comprises a clutch coupled to a main drive of the machine.

14. A system according to Claim 13 wherein engagement of the clutch is synchronised to a timing of the machine to avoid interference between the thread bar and parts of the machine.

15. A system according to any one of the preceding Claims wherein the machine is a paper converting machine.

16. A method of threading a web through a machine of the type having a plurality of nips formed by respective pairs of closely adjacent rolls for performing operations on the web passing through the machine, the method comprising a) clamping a leading edge of a web in a thread bar located at a starting station and positioned transverse to a desired path for the web in the machine; b) opening the nips in the closely adjacent rolls in the machine by an amount sufficient to clear the thread bar; c) drawing the web along the desired path through the machine by a pair of flexible and inextensible filament members attached to the thread bar while maintaining the thread bar transverse to the desired path; d) and returning the thread bar to the starting station once the web is threaded along the desired path in the machine.

17. The method of Claim 16 wherein step a) further comprises holding the leading edge of the web between a pair of parallel members.

I

18. The method of Claim 16 or 17 wherein step a) further comprises using magnetic attraction between the parallel members to clamp the leading edge of the web in the thread bar.

19. The method of Claim 16, 17 or 18 wherein the filament members comprise roller chains.

20. The method of Claim 16, 17 or 18 wherein the filament members comprise belts.

21. The method of any one of Claims 16 to 20 wherein step c) further comprises engaging a clutch coupled to a main drive of the machine to draw the web through the machine.

22. The method of Claim 21 wherein the clutch is synchronised to the operation of the machine to avoid interference between the thread bar and parts of the machine.

23. A method according to any one of Claims 16 to 22 wherein the machine is a paper converting machine.

24. Apparatus for clamping a leading edge of a web comprising: a) a base member extending parallel to a leading edge of a web of material; b) an elongated ferromagnetic tube supported on an elastic cord a predetermined distance away from the base member; and c) a plurality of magnets carried by the base member and located to attract and retain the tube to the base member when the tube is placed near the base member such that the leading edge of the web is retained between the base member and the tube by the magnetic attraction between the magnets and the tube.

25. The apparatus of Claim 24 wherein the base member has f irst and second ends separated by an intermediate potion and the magnets are spaced closer together at the f irst and second ends than they are in the intermediate portion.

26. An automatic web threading system substantially as herein described with reference to and as shown in the accompanying drawings.

27. A method of threading a web through a machine substantially as herein described with reference to the accompanying drawings.

28. An apparatus for clamping the leading edge of a web substantially as herein described with reference to and as shown in the accompanying drawings.

29. Any novel feature or combination of features disclosed herein.