Method and apparatus for rewinding

Information

  • Patent Grant
  • 6202955
  • Patent Number
    6,202,955
  • Date Filed
    Tuesday, July 13, 1999
    24 years ago
  • Date Issued
    Tuesday, March 20, 2001
    23 years ago
  • Inventors
  • Examiners
    • Jillions; John M.
    Agents
    • Stoltz; Melvin I.
Abstract
A method of differential rewinding includes mounting a plurality of cores on a shaft (20) formed with a plurality of apertures (21) containing ceramic balls (23) urged outwardly into engagement with the cores by means of an inflatable sleeve (25).
Description




FIELD OF THE INVENTION




This invention relates to a method and apparatus for rewinding and is specifically concerned with differential rewinding.




The concept of differential rewinding has been in use for many years and is adopted to accommodate variations in tension or calliper across the web when rewinding material cut from a single roll onto a number of rewind coils.




Traditional methods of differential rewinding rely on the rewind cores slipping around a shaft which is being driven at a greater speed than the moving web of material. One arrangement for effecting differential rewinding is shown in

FIG. 1

of the accompanying drawings.




In

FIG. 1

, a number of rewind cores


10


are mounted, either directly or via adaptors, on a rewind shaft


11


which is driven at a slight overspeed. Steel friction collars


12


keyed to the rewind shaft


11


are mounted on each side of each rewind core


10


or adaptor, and spacer cores


13


are positioned between adjacent rewind cores


10


.




In operation, torque is transmitted to each of the rewind cores


10


, which are free to rotate relative to the rewind shaft


11


, such torque being transmitted frictionally through the steel driving collars


12


which are keyed to the rewind shaft


11


and are loaded axially against the cores


11


and


13


as indicated by the arrows in

FIG. 1

by a pneumatic piston and cylinder mechanism. As the pneumatic pressure is increased, the frictional forces and the transmitted torque increases proportionally. This arrangement is such as to allow differential slip to occur permitting each individual strip to be rewound under optimum conditions to form a rewind roll


14


.




More recent methods of providing differential rewinding have Involved the use of torque-responsive chucks on a keyed shaft and have improved the effectiveness of the differential system. The chucks each have a bronze bush in the centre with a low coefficient of friction and are assembled with mechanically expanded leaves that grip the cores.




The torque-responsive chuck arrangements eliminate the need to remove the spacers and the drive collars from the rewind shaft during reel removal. The chucks retract and release the cores allowing the finished reels to slide over the spacers. The shaft only requires dismantling when the slit pattern is changed to re-positon the chucks.




Although the use of torque-responsive chucks provides an improvement over the arrangement shown In

FIG. 1

, it does have a serious disadvantage in that it involves a reduction in the diameter of the rewind shaft to accommodate the chucks. This results in a dramatic reduction in strength.




The objects of the present invention thus Include the provision of an improved method of differential rewinding and the provision of an improved apparatus for differential rewinding which offer significant advantages over the known systems outlined above.




SUMMARY OF THE INVENTION




According to a first aspect of the present invention there is provided a method of differential rewinding which includes mounting a plurality of cores on a shaft formed with a plurality of apertures containing roller elements urged outwardly into engagement with the cores.




According to a second aspect of the invention there is provided a differential rewinding apparatus comprising a shaft on which, in use, a plurality of cores are mounted, a plurality of apertures in the shaft, roller elements in the apertures and means for urging the roller elements outwardly into engagement with the cores.




Each of the roller elements is preferably arranged to act between a core and a torque-transfer element formed of a material which has a coefficient of sliding friction with the roller elements lower than the coefficient of sliding friction between the roller elements and the cores. The roller elements will accordingly tend to roll relative to the cores.




The cores are preferably formed of cardboard or plastic and the roller elements are preferably ceramic balls, while the torque-transfer elements are preferably in the form of steel cups within which the ceramic balls are seated.




The means for urging the roller elements, i.e. the ceramic balls, into engagement with the cores preferably comprises an inflatable sleeve contained within the rewind shaft and so arranged that, when the pressure within the inflatable sleeve is increased, the torque transferred to the cores is increased.




The apertures in the rewind shaft are preferably arranged in the form of a multi-start helix so that, when cores of different widths are placed side-by-side on the rewind shaft, the number of roller elements which engage a particular core will depend on the width of the core Thus, as the width of a core is increased, the total torque transmitted to that core will be increased. It will thus be possible to rewind cores of different widths at the same time.




Means may be provided for preventing the accumulation of dust between the ceramic balls and the steel cups. Said means preferably comprises means for causing a flow of air out through the apertures in the rewind shaft.




The method and apparatus of the present invention are such that it is not necessary to fit spacers between adjacent cores. Any slit widths can accordingly be accommodated without resetting so that the present invention will enable the machine downtime to be decreased by up to 30% while improving the rewind shaft strength and achieving a dramatic increase in the reel quality.











BRIEF DESCRIPTION OF THE DRAWING





FIG. 1

, as mentioned above, shows a traditional form of differential rewinding apparatus,





FIG. 2

is a partly broken away plan view of a differential rewind shaft assembly in accordance with the present invention,





FIG. 3

is a transverse sectional view of the shaft assembly of

FIG. 2

,





FIG. 4

is a longitudinal sectional view of one end of the shaft assembly of

FIG. 2

,





FIG. 5

is a longitudinal sectional view of an intermediate portion of the shaft assembly of

FIG. 2

,





FIG. 6

is a longitudinal sectional view of the other end of the shaft assembly of

FIG. 2

, and





FIG. 7

is a view corresponding to

FIG. 4

but showing an alternative form of differential rewind shaft fitted with a cleaning assembly.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




The shaft assembly shown in

FIGS. 2

to


6


includes a high quality steel tube


20


which is turned to a diameter of 0.8 mm. less than the internal diameters of the cores onto which the rolls of paper or other flexible materials are to be rewound. A large number of apertures


21


are machined in the steel tube


20


, the apertures


21


being arranged in the form of a three-start helix so that, as shown in

FIG. 2

, there is a repeated pattern comprising three apertures


21


A spaced apart 120° contained in a first common plane, three apertures


21


B in a second common plane offset 40° from the apertures


21


A in the first common plane, and three apertures


21


C in a third common plane offset 40° from the apertures


21


B in the second common plane.




Each of the apertures


21


is counterbored and, in the completed assembly, each aperture


21


contains a steel support cup


22


, a ceramic ball


23


and a brass retaining ring


24


, all of which are fitted from the outside of the shaft assembly.




A rubber bladder or sleeve


25


mounted on a tubular steel cartridge


26


is mounted within the bore of the steel tube


20


. the rubber bladder


25


being attached to the steel cartridge


26


by means of hose clips


27


. The cartridge


26


is secured at its ends to mounting elements


28


and


29


fixed to the steel tube


20


so that the steel cartridge


25


and the rubber bladder


25


will rotate in unison with the steel tube


20


.




A compressed air supply (not shown) is connected to the shaft assembly through a rotary union and into one end of the shaft assembly expanding the rubber bladder


25


so as to cause the ceramic balls


23


to protrude through the retaining rings


24


and against the inside surfaces of the cardboard rewind cores (not shown).




The steel support cups


22


transmit the force exerted by the bladder


25


to the balls


23


. The coefficient of sliding friction between the ceramic material and steel is lower than that between the ceramic material and cardboard The balls


23


will thus slide preferentially relative to the steel support cups


22


and will rotate against the inside surfaces of the cores.




The higher the air pressure within the rubber bladder


25


, the greater the frictional forces acting between the steel cups


22


and the ceramic balls


23


which, in turn, increases the torque transmitted to the individual cores. The total torque transmitted to a particular core will depend on the number of balls


23


which it engages, i.e. on the width of the core.




The rotational speed of the shaft assembly is greater than that of the rewind cores causing them to slip around the tube


20


. The action of the balls


23


pressed against the inside surfaces of the cores causes small grooves to appear immediately around the bores of the cardboard cores. The ceramic balls


23


will be located in these small grooves preventing any axial displacement of the cardboard cores relative to the shaft assembly and guaranteeing a good edge profile on the rewinding reels.




The shaft assembly is such that spacers between the cores are not required and it can accommodate any slit widths without resetting. The use of the shaft assembly and the method of differential rewinding of the present invention will therefore decrease the machine downtime by up to 30%, and possibly more, while improving the shaft strength and dramatically improving the reel quality.




Turning next to

FIG. 7

, this shows the apparatus of

FIGS. 2

to


6


fitted with a cleaning system. It includes a manual spool valve


30


at the end of the shaft assembly at which the supply of compressed air Is connected. The manual spool valve


30


is shown in

FIG. 7

in its cleaning position but is normally in its running position displaced upwardly from that shown in FIG.


7


.




When in its running positions the spool valve


30


provides communication between an inlet passage


31


and an air feed passage


32


connected to the interior of the bladder


25


. When in its cleaning position, the spool valve


30


provides communication between the inlet passage


31


and an air feed passage


33


which communicates with the space between the steel tube


20


and the bladder


25


.




The mode of operation of the system shown in

FIG. 7

is as follows:




a) when the shaft assembly has finished running and is stationary the air is expelled from the bladder


25


,




b) the operator then pushes the spool valve


30


into the cleaning position, i.e. as shown In

FIG. 7

, and operates a push button on the control desk controlling the differential rewinding operation. This then supplies the inlet passage


31


with a pre-set cleaning pressure for a set amount of time, and




c) the air passes into the air feed passage


33


and exits through the apertures


21


, purging the balls


23


and cups


22


of dust and dirt.




The operator then removes the reels from the steel tube


20


and inserts the new cores on to the shaft. The set amount of time at cleaning pressure has finished and the operator switches the manual spool valve


30


back into the run position, ready for the next cycle.




It will be appreciated that this sequence of operations is tied in to the machine sequencing to ensure that, every time the shaft is unloaded and then loaded, the ceramic balls


23


and the stainless steel seats


24


are cleaned.



Claims
  • 1. A differential rewinding apparatus comprising a shaft on which, in use, a plurality of cores are mounted, a plurality of apertures in the shaft, roller elements in the apertures and means for urging the roller elements outwardly into engagement with the cores, and in which each of the roller elements is arranged to act between a core and a torque-transfer element formed of a material which has a coefficient of sliding friction with the roller elements lower than the coefficient of sliding friction between the roller elements and the cores.
  • 2. Apparatus as claimed in claim 1, for use with cores formed of a material selected from cardboard and plastic, in which the roller elements are ceramic balls.
  • 3. Apparatus as claimed in claim 2, in which the torque-transfer elements are steel cups within which the ceramic balls are seated.
  • 4. Apparatus as claimed in claim 3, which includes means for preventing the accumulation of dust between the ceramic balls and the steel cups.
  • 5. Apparatus as claimed in claim 4, in which the means for preventing the accumulation of dust comprises means for causing a flow of air out through the apertures in the rewind shaft.
Priority Claims (1)
Number Date Country Kind
9815016 Jul 1998 GB
US Referenced Citations (8)
Number Name Date Kind
3815836 Munnekehoff et al. Jun 1974
3817468 Smolderen et al. Jun 1974
4135677 Warczak Jan 1979
4175712 Schippers et al. Nov 1979
4220291 Papa Sep 1980
4496114 Kataoka Jan 1985
4693431 Kataoka Sep 1987
5971314 Essert Oct 1999
Foreign Referenced Citations (4)
Number Date Country
296 04 307 U Jan 1979 DE
195 15 724 Nov 1996 DE
0 866 017 A1 Sep 1998 EP
WO 9514630 Jun 1995 WO
Non-Patent Literature Citations (1)
Entry
Anwendungsspeizifische Spannelemente Fuer LWickelwellen Papier + Kunststoff Verarbeiter vol. 31, No. 1, XP 000584425, dated Jan. 25, 1996.