Winding method and apparatus

Abstract

A running web of sheet material (2) is wound onto a roll (8). An empty core (30) is arranged at a transfer position to receive the web when the roll (8) is completed. A wrap roller (20) is moved so as to draw the web upstream of the core (30) around a portion of the circumference of the core. A head assembly (40) of a cross-cut mechanism then advances, wrapping the web upstream of the core (30) around the core. A spring loaded blade (52) is then advanced so as to cut the web and to force the end of the web into the inrunning nip between the wrap roller and the core. The head assembly and the wrap roller are then withdrawn to their standby positions and the core (30) moved from the transfer position to a running position while the completed roll (8) is unloaded.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] NOT APPLICABLE

BACKGROUND OF THE INVENTION

[0002] The invention relates to a method and an apparatus for winding sheet material.

[0003] Sheet feed materials after processing are required to be wound onto easily managed rolls. These are commonly wound onto cardboard cores of 3″ (76 mm) I/D (internal diameter) but cores can vary in bore diameter and wall thickness and the material from which they are manufactured. The width of the core is selected to suit the sheet product width and for cosmetic or process purposes it is desirable to have the edges of the sheet material aligned accurately with the edge of the core.

[0004] Some products are alternatively wound to form a roll with a pre determined inside diameter with no supporting core and need to be easily removed from the winding mandrel when finished.

[0005] Typical sheet material products have widths from 30 mm to 1600 mm, but product widths outside this range do exist.

[0006] Bulk, single sheet, materials can be processed in a rewinding machine though many materials are also slit longitudinally during rewinding to avoid unnecessary further processing. This process is commonly called slitting and rewinding. Rewind roll diameters may vary from finished slit rolls of 50 mm diameter to bulk rolls of 1000 mm diameter and more.

[0007] Many processes carried out on sheet materials, such as printing, coating etc, benefit from having a constant running speed, or web speed, therefore requiring the changeover from one rewind reel to the next at the output of a processing machine to be done at speed. Machines are available to do this for slow web speeds, or while the web speed is slowed temporarily, and are generally designed to have multiple rewind shafts mounted on a turret which rotates about a centre point to bring an empty shaft into the running web path and which use a varying array of designs to cross cut the web and to transfer the material onto the empty shaft while the material is still running. A typical web speed is 200 meters per minute (mpm) but this can vary from a few mpm to 300 mpm. Faster web speeds have been achieved but are unusual.

[0008] Current technology uses many different types of system for achieving the desired changeover to a new reel while a web is running but these suffer the disadvantage that they need to attach the web to the new reel by means of a fold or a tuck on the starting wrap of material around the new reel. Conventional solutions also have severe speed restrictions disadvantageously requiring the producing or rewinding machine to be slowed down during the transfer process in an attempt to alleviate the problem of how to attach the web to the new reel.

[0009] Another problem in conventional solutions is lack of flexibility. For example, conventional reel changers may be unable to handle different core widths from, say, 25 mm to 150 mm without tooling changes, which on continuous production machinery is a considerable disadvantage.

BRIEF SUMMARY OF THE INVENTION

[0010] The invention provides a method and an apparatus for winding a sheet material as defined in the appended independent claims. Preferred or advantageous features of the invention are set out in dependent subclaims.

[0011] In one embodiment, the invention operates as follows to wind the running web at the output from a processing or rewinding machine. Initially, the running web of sheet material is wound onto a roll. An empty core is arranged at a transfer position to receive the web when the roll is completed. A wrap roller is moved so as to draw the web upstream of the core around a portion of the circumference of the core. A head assembly of a cross-cut mechanism then advances, wrapping the web upstream of the core around the core. A spring loaded blade is then advanced so as to cut the web and to force the end of the web into the inrunning nip between the wrap roller and the core. The head assembly and the wrap roller are then withdrawn to their standby positions and the core moved from the transfer position to a running position while the completed roll is unloaded.

[0012] Some embodiments of the invention may thus provide a winder, or rewinder, in which the output reel onto which the web is wound after processing may be changed on the fly, without stopping or preferably without even slowing down the web of material running through the machine. Advantageously, some embodiments of the invention may also enable this to be done without damaging the end of the web which is guided onto the new reel, for example without either folding, tucking or glueing the end of the web.

[0013] Advantageously, embodiments of the invention may allow the web to be wound onto a core, such as a cardboard core, or onto a reel without a core.

[0014] It can also be seen that the web width which can be handled by the method and apparatus according to some embodiments of the invention is limited only by the widths of the wrap roller and the cutter. Embodiments of the invention may thus provide flexibility to handle a large range of web widths without retooling.

[0015] It is preferable to be able to start winding a web on a new reel at as high a web speed as possible, in order to avoid slowing down the machine from which the web is output. Embodiments of the invention may advantageously avoid any need for folding, tucking or sticking the web to the new reel and minimizes the handling of the cut end of the web, and may therefore advantageously be able to handle high web speeds.

[0016] Most problems in achieving a tuck-free start on a new reel for a web running at as much as 200 mpm revolve around two main issues.

[0017] First, for this web speed the cutting blade speed needs to be of the order of 3.33 m/second, so that the blade is traveling at the same speed as the web. Most air cylinder activated systems are limited to 1 m/s, for example, and so may be unsuitable. One embodiment of the invention therefore uses a serrated cross cut blade actuated by short stroke springs, which are advantageously sized to accelerate the blade to web speed within a short distance, such as about 4 mm of travel. This mechanism and the reloading of the spring energy by resetting the blade and compressing the springs may all be achieved mechanically, allowing a high degree of precision on the blade release position.

[0018] Second, it is advantageous to be able to wrap the new reel, whether a core or a shaft, with the running web and to minimize the length of free web after cutting. Optimization of this process in one embodiment requires precision in the release of the blade and a wrap of the web around the core greater than about 300°. Hence when the blade is released it preferably moves into an inrunning nip (between the wrap roller and the reel) at line speed (web speed) forcing the severed web into the inrunning nip with no excess web. This may advantageously eliminate the tuck or fold over at the cut end of the web.

[0019] The cutter, or blade assembly, preferably allows the web to run around a small radius with the blade positioned at or slightly downstream from the exit from the radius. Miniature individually-sprung rollers may provide the small radius and apply rolling pressure to the incoming web, urging it against the reel. The pressure should preferably be such that, at the maximum design web tension of the machine with which the winding apparatus is to operate, the friction between the rollers, the web and the reel will continue to feed the web at full tension. The web tension is preferably controlled by driving the reel on which the web is wound. It may therefore be advantageous for full tension to be obtainable as soon as the web starts to be wound on the new reel. Individual loading of the miniature rollers is preferable because it ensures that slit webs with individual cores or webs of different widths can still be processed, allowing for possible dimensional or positioning errors in core sizes etc.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Specific embodiments of the invention will now be described by way of example with reference to the drawings, in which;

[0021] FIG. 1 shows an apparatus according to a first embodiment of the invention in a first configuration, before operation;

[0022] FIG. 2 shows the apparatus of FIG. 1 in a second configuration;

[0023] FIG. 3 shows the apparatus of FIG. 1 in a third configuration;

[0024] FIG. 4 shows the apparatus of FIG. 1 in a fourth configuration;

[0025] FIG. 5 shows an enlarged side view of the cutter assembly of FIG. 4;

[0026] FIG. 6 shows an enlarged side view of the cutter assembly of FIG. 5 with the blade extended;

[0027] FIG. 7 shows an enlarged partial front view of the cutter assembly of FIG. 5; and

[0028] FIG. 8 shows an enlarged partial front view of the cutter assembly of FIG. 5 with the blade extended.

DETAILED DESCRIPTION OF THE INVENTION

[0029] FIG. 1 illustrates a winding apparatus according to a first embodiment of the invention. The winding apparatus receives an incoming web 2 of sheet material from a web processing machine such as a printer or rewinder. The web runs over guide rollers 4, 6 and is then wound onto a roll 8. The roll is supported and driven by a shaft 10, which is one of four drivable shafts 10, 12, 14, 16 mounted on a rotating turret 18. The turret is conventional, providing four winding stations at 90° intervals so that successive 90° rotations of the turret move the winding stations between a running position, an offload position, a core load position and a transfer position. During normal operation, the web is wound onto a roll in the running position. When the roll reaches a predetermined size, the web is cut and winding begins in the transfer position, as described below. The turret is then rotated through 90° to bring the completed roll into the offload position, where it is unloaded. The same rotation brings an empty shaft into the core load position, where a cardboard core is loaded onto the shaft in preparation for movement into the transfer position.

[0030] FIG. 1 also shows a moveable wrap roller 20 in its standby position. The wrap roller is rotatably mounted at the end of a pivoting arm 22. The position of the pivoting arm is controlled by a pneumatic driver 24. The pivot point of the arm and the pneumatic driver are mounted on a translating carriage 26, which is also pneumatically driven. Computer control of the pivot and carriage arm enables substantial flexibility in the control of the position and movement of the wrap roller 20.

[0031] FIG. 1 also shows a cutter, or cross cut unit, 28 in its standby position. This will be described in more detail below.

[0032] FIG. 2 shows the winding apparatus of FIG. 1 in a first stage of transferring the web to a new core 30 on the shaft 12 in the transfer position. In this first stage, the actuator 24 is driven to rotate the pivot arm 22 and to draw the wrap roller across the path of the running web. This deflects the web and brings it into contact with the empty core 30.

[0033] FIG. 3 illustrates a further stage in the operation of the embodiment. To reach this stage, the carriage 26 is driven by its actuator in order to move the wrap roller past the empty core 30. The pivot arm actuator 24 then extends until the wrap roller contacts the empty core 30. As shown in FIG. 3, this movement wraps the web around the core 30 as far as possible without the running web upstream of the wrap roller contacting the web which is wrapped around the core.

[0034] At this stage, the wrap roller is positioned approximately between the core and the centre of the turret and the web is running at full speed, being wound onto the roll 8 at the running position.

[0035] FIG. 4 illustrates the operation of the cutter 28. FIGS. 5 to 8 show the cutter and its head assembly 40 in more detail.

[0036] The cutter comprises a fixed pneumatic driver cylinder 42 from which a rod 44 carrying the head assembly is extendable. The head assembly is also supported by two rods 45 slidable in linear guides 47. The head assembly thus moves so as to pick up the running web between the empty core 30 and the roll 8 and to deflect it towards the inrunning nip between the wrap roller and the empty core. When the head assembly is fully extended, as shown in FIGS. 4, 5, 6 and 8, it urges the web against the empty core by means of one or more spring loaded miniature rollers 46. Downstream from the miniature rollers, the web passes around the end of a small radius nose plate 48 and around a guide roller 50 before running onto the roll 8. The miniature rollers, the nose plate and the guide roller are all carried by the head assembly. At this point, the web is wrapped around a large portion of the circumference of the empty core, such as 3000 or more of the circumference.

[0037] The head assembly 40 also comprises a serrated cross cut blade 52 which is positioned adjacent the nose plate on its upstream side. The blade extends across the entire width of the web and is arranged to be driven beyond the end of the nose plate to cut the web. The blade is driven by coil springs 54 mounted within the head assembly. FIGS. 5 and 7 show the blade in its cocked position with the coil springs compressed, with the blade retained by a latch or trigger mechanism 55.

[0038] As the head assembly reaches its fully extended position, i.e. the position shown in FIGS. 4, 5, 6 and 8, the blade trigger is released and the blade is driven forward by the springs so that its edge extends beyond the tip of the nose plate, cutting the web. The springs accelerate the blade rapidly to a speed comparable to that of the running web so that the cut end 58 of the running web is carried with the blade as it moves beyond the nose plate and is guided or forced by the blade into the nip 56 between the empty core and the wrap roller. FIGS. 6 and 8 show the head assembly with the blade and the driving springs extended. The blade should not touch the wrap roller or the web on the reel, to avoid damaging them, but may come within as little as 1 mm of them. At this point, the web completely encircles the empty core and so its cut end is drawn around the core, beneath the subsequent layers of the web being wound onto the core.

[0039] The head assembly can now be withdrawn to its standby position, as can the wrap roller. The turret is then rotated through 90° so that the new core occupies the running position and the completed roll 8 of web can be unloaded from the offload position.

[0040] When the head assembly of the cross cut unit is withdrawn, the blade is recocked by compressing the coil springs and resetting the trigger. This returns the apparatus to the normal running position shown in FIG. 1. The recocking and trigger mechanisms are shown in FIGS. 7 and 8. As shown in FIG. 7, as the head assembly is withdrawn, a lever 60 on each side of the blade abuts against a fixed stop 62 and pivots about a pivot point 64. The opposite end 65 of each lever acts on the blade to raise it into the cocked position, compressing the springs. When the blade reaches the cocked position, the triggers 55 on each side of the blade latch. Each trigger comprises an arm 66 which pivots about a pivot point 68. A spring 70 acts on each arm to urge a lower end of the arm 72 to engage and retain the blade automatically when it reaches the cocked position.

[0041] Advantageously, as the head assembly advances, each blade trigger is operated by contact between the trigger and a stationary stop when the head assembly advances to a predetermined position. Each stop is preferably a cam surface (not shown) which acts on an upper end 74 of each trigger arm to cause the trigger arm to pivot and release the blade. Each stop is preferably adjustable so that the trigger operation can be accurately set. The blade is thus released at an accurately predetermined position at full power, driven by the springs. In a particular embodiment, it accelerates over the first 4 mm of its travel to reach its top speed and then travels a further 4 mm to cut and push the web into the inrunning nip. Immediately this has happened, the head assembly retracts to its safe, standby position, reloading the springs. The retraction is driven by the pneumatic driver 42, 44 under computer control.

[0042] The cutting and wrapping of the roll takes a fraction of a second and in practice looks like one continuous movement of advance and retraction of the cutter head assembly. This high speed of operation is advantageous because the cutting operation needs to match the running speed of the web, which may be 200 meters per minute (3.3 meters per second) or more.

[0043] It is highly advantageous to achieve a rapid and accurate blade release and to maximize the wrap angle of the web around the empty core before the blade is released. It may be possible to drive the blade pneumatically or electrically but with fast-moving webs it is likely to be necessary to use the faster blade movement achieved by the spring-driven embodiment described above. In lower web speed applications, or if faster blade speeds can be achieved, other blade drive systems may be used.

Claims

1. A method for winding a sheet material, comprising:

deflecting the path of a running web of the material to run between a wrap roller and a reel onto which the web is to be wound, and then around a portion of the circumference of the reel;

cutting the running web at a point downstream from the reel; and

inserting the cut end of the web between the reel and the wrap roller.

2. A method according to claim 1 in which the web is cut by a blade advancing at a speed matching that of the running web and in which the advancing blade carries the cut end of the web into an inrunning nip between the reel and the wrap roller.

3. A method according to claim 2 in which, before it is cut, the web is positioned near the inrunning nip by a guide element, such as a nose plate, and the blade cuts the web substantially adjacent to the guide element and before the web reaches the guide element.

4. A method according to claim 1 in which the web is deflected so that it runs in the shape of an “S” around the wrap roller and the reel.

5. A method according to claim 1 in which the web is deflected by the step of;

moving the wrap roller relative to the reel to wrap the running web around at least 180° and preferably more than 270° of the circumference of the reel.

6. A method according to claim 1 further comprising after the cut end of the web has been inserted between the wrap roller and the reel, withdrawing the wrap roller out of contact with the web and winding the web onto the reel.

7. A method according to claim 1 in which the cut end of the web is inserted between the reel and the guide roller such that the web is in contact with the reel around the entire circumference of the reel.

8. An apparatus for winding a sheet material, comprising:

a reel onto which a web of the sheet material is to be wound;

a wrap roller which is movable relative to the reel to deflect a running web to run between the wrap roller and the reel and then around a portion of the circumference of the reel; and

a cutter for cutting the running web at a point downstream from the reel and inserting the cut end of the web between the reel and the guide roller.

9. An apparatus according to claim 8 in which the web is cut by a blade advancing at a speed matching that of the running web and in which the advancing blade carries the cut end of the web into an inrunning nip between the reel and the wrap roller.

10. An apparatus according to claim 9 in which, before it is cut, the web is positioned near the inrunning nip by a guide element, such as a nose plate, and the blade cuts the web substantially adjacent to the guide element and before the web reaches the guide element.

11. An apparatus according to claim 8 in which the wrap roller can be withdrawn after the cut end of the web has been inserted between the wrap roller and the reel, while the web is wound onto the reel.

12. A roll of sheet material wound using the method defined in claim 1.

13. A roll of sheet material wound using the apparatus defined in claim 8.