GB2184499A - Clutch in take-up shaft for sheet rewinder - Google Patents

Abstract

A take-up shaft for a sheet rewinder comprises a hollow shaft 1 provided in its peripheral wall with through-holes 3, a plurality of drum rings 15 rotatably fitted around the hollow shaft, plungers 6 inserted one in each through-hole 3, support rings 17 provided at the opposite ends of the drum rings 15, and urging means disposed in the hollow shaft and adapted for outwardly urging the plungers. The hollow shaft 1 is brought into engagement with the drum rings 15 by means of the plungers 6 being outwardly projected by the urging means, consequently to permit the torque of the hollow shaft to be transmitted to the drum rings. The urging means may comprise an air tube 10. Alternatively the plungers may each form part of a piston (Figure 5). <IMAGE>

Description

SPECIFICATION Take-up shaft for sheet rewinder This invention relates to atake-up shaftfor a sheetslitter/rewinder, in which a plurality of slit sheets slit bya slitter are taken upon cores fitted on drum rings rotatably fitted on a drive shaft driven for rotation bythe torque ofthe drive shafttransmitted to the drum rings via friction members in frictional engagement with the drum rings.

In a sheet rewinder in which a plurality of slit sheets obtained from a wide sheet by use of a slitter aretaken up on atake-up shaft, after slit sheet rolls have been formed by taking up a prescribed amountofsheet,the take-up shaft is taken outfrom the rewinder togetherwith the sheet rolls and the take-up shaft is then with- drawn from the sheet rolls, whereafterthetake-up shaft is then mounted again on the rewinder.

Recently, there has been proposed a sheet slitter/rewinder, which is provided with a take-up shaftwith- drawal mechanism, and predetermined slit sheet rolls formed on the take-up shaft are taken out from the take-up shaft and transported to the outside while the take-up shaft is held at a set position for the take-up, as disclosed in U.S. patent No.4,431,142.

Meanwhile, there are sheet roll cores ofdifferent diameters, e.g.,3 inches and 6 inches, and cores of given diameters are used according to purpose. It is uneconomical to preparetake-up shafts of different diameters corresponding to the cores of the respective diameters. Therefore, drum rings having different outer diameters corresponding to the respective core diameters are prepared, and onlythe drum rings are replaced according tothe inner diameter of the core used forthetake-up.

Japanese Patent Publication SHO 55(1980)-16941 discloses a take-up shaft, which comprises a drive shaft driven for rotation and having the outer periphery formed with axially continuous grooves, expansible tubes accommodated in the axial grooves, and brake shoes fitted on the outer periphery ofthe drive shaft. The expansible tubes are outwardly expanded by being supplied with air so as to bring the brake shoes into frictional engagementwith the inner periphery of carriers orcorewhich are rotatably fitted on the drive shaft for tasking up sheets. This take-up shaft, however, has a complicated construction and requires cumbersome assembly.In addition,the replacement and maintenance of drum rings requires great deal oftime and labor.

Japanese Patent Publication SHO 55(1980)-37461 discloses a take-up shaft, which comprises a hollow shaft, an expansible airtube accommodated therein and three-piece split rings provided on the airtube. Rods project outwardly from the individual pieces ofthe three-piece slit rings, each rod carrying a steel ball provided at the free end. The steel balls at the end of the rods are urged into engagement with grooves formed in the inner periphery of drum rings, thereby making the drum rings integral with the hollow shaft.

In this take-up shaft, however, high machining precision and assembling precision are required to obtain registration between the steel balls and grooves. In addition, each steel ball atthe end of each rod is in contact with the associated drum ring at a fixed position thereof. Therefore the frictional surface of the drum ring, i.e., the inner periphery thereof, with the steel ball is liable to be worn locally, resulting in deviation of the transmitted torque.Further, while the drum rings are held coaxiallywith the hollow shaft bytheurging force ofthe rods while the load is light, i.e., while the taken-up sheet roll diameter is small, as the sheet roll diameter increases the drum rings deviate with respecttothe drive shaftdueto the load ofthe sheet rolls acting on the drum rings. In this case, the drum ring inner periphery and drive shaft outer peripheryare rotated in contact with each other, thus producing scars and scratches on the drum ring inner periphery.

An object ofthe invention is to provide a take-up shaftfor a sheet slitter/rewinderwhich permits uniform and accurate transmission of thetorque ofthe hollowshaftto cores overthe entire lengththereof.

Another object of the invention is to provide a take-up shaft for a sheet slitter/rewinderwhich is simple in construction and capable of easy assembly, machining and maintenance.

Afurtherobject of the invention isto provide a take-up shaftfora sheetslitter/rewinder, which can be readily assembled without need of high precision positioning of drum rings and frictionally driven sections and hasexcellentdurability.

To attain the above objects of the invention, there is provided a take-up shaft for a sheet rewinderwhich comprises a hollow shaft having a plurality of through-holesformed in the peripheral wall at predetermined intervals in the circumferential and axial directions, each through-hole having an inner projection provided at the inner end ofthe hole, a plurality of drum rings rotatablyfittted on the hollow shaftto close the outer open ends ofthe through-holes, the inner periphery ofthe drum rings serving as africtional surface, plungers inserted one in each through-hole, each plunger having at least one hook portion greater in size than the inner diameter of the inner projection, support rings provided at the opposite ends ofthe inner periphery of the drum rings, the inner peripheryofthe support rings being in contact with the outer peripheryofthe hollow shaft, and urging meansforoutwardlyurging the plungers through the interiorofthe hollow shaft.

With this take-up shaft, a slight variation of the position of contact between the drum ring frictional surface and plunger has no adverse effect on the results. Thus, the shaft can be easily machined and assembled, and moreover local wear of the drum rings can be suppressed. Further, the torque ofthe hollow shaft can be reliably transmitted to the drum rings. Further, the plungers can be readily inserted into and taken outfrom thethrough-holesfrom the side ofthe outer peripheryofthe hollow shaft. Moreover, since the support rings are provided in direct contact with the inner periphery ofthe drum rings and the outer periphery of the hollow shaft to supportthe drum rings in coaxial relation to the hollow shaft, the hollow shaft and drum rings are rotated without possibility of eccentric deviation from one another.It is thus possible to eliminate scaring and scratching ofthe drum ring inner periphery in frictional contact with the plunger, thus eliminatingvari- ations in the frictional force and maintaining accurate transmitted torque.

Figure lisa front view, partly in section, showing a first embodiment of the take-up shaft according to the invention; Figure2 is a sectional view taken along line ll-ll in Figure 1; Figure3is an enlarged sectional view showing an essential partofthetake-upshaftshown in Figure 1; Figure 4is a sectional view showing an essential part of a second embodiment ofthe take-up shaft accord- ing to the invention; Figure 5is an enlarged sectional view showing an essential part ofthe take-up shaft shown in Figure4; Figure 6 is a schematic representation of a system for explaining the slitsheettake-up control using the take-up shaft according to the invention;; Figure 7is a block diagram showing a take-up tension controller shown in Figure 6; Figure 8is a block diagram showing afirstexampleofa frictional torque controller; Figure 9 is a block diagram showing a second example ofthe frictional torque controller; Figure 70 is a block diagram showing a third example of the frictional torque controller; and Figure 11 is a block diagram showing a fourth example of the frictional torque controller.

Figures 1 to 3 illustrate a first embodiment ofthetake-up shaft according to the invention. Reference numeral 1 designates a shaft having a hollow portion 1a rotatably mounted at opposite ends via bearings 2 in a rewinder. One end ofthe hollow shaft 1 is coupled to and driven bya drive mechanism (not shown). Inthis embodiment, the peripheral wall ofthe hollow shaft 1 has a plurality of sets ofthrough-holes 3 arranged at predetermined intervals in the axial direction to penetrate the hollow portion and outer circumference. Each through-hole set consists of three radially uniformly spaced-apartthrough-holes 3 in this embodiment.The wall surface of each through-hole3 has an inner projection 4formed atthe inner end ofthe hole.Aretainer ring 5 is removably provided by suitable means, e.g., screwing orfitting, in the wall surface of eachthrough- hole 3 at or adjacent to the outer end thereof. A plunger 6 made of a heat-resistantwear-proof material is inserted in each through-hole 3. In this embodiment, each plunger 6 has a flange 7 having an outerdiameter smallerthanthe diameter ofthe hole 3 butgreaterthanthe inner diameter ofthe inner projection 4and inner diameterofthe retainer ringS. Thus, the plunger 6will not be detached from the through-hole 3, while itcan be freely moved radially with respect to the hollow shaft 1 over a predetermined range.

The plunger6 may have anyofvarious other configurations. Forexample, instead oftheflange itmayhave protuberances provided at an intermediate portion, or it may have a reduced-diameter portion which penetrates the inner projection 4 ofthe through-hole 3.

The inner end 6a of each plunger6 is in contact with the outer surface ofan airtube 10within the hollow shaft 1.The airtube 10 can be expanded and contracted according to the pressure of compressed airsupplied to itthrough an ain supply duct9 extending through a rotaryjoint8 provided adjacent to one end of the hollow shaft 1. Drum rings 15corresponding in numbertothe number ofthe through-hole sets, are loosely fitted on the outer periphery of the hollow shaft 1. Each drum ring 15 covers the outer end ofthethroughholes 3 in each through-hole set. A pair of support rings 17 made of a wear-proof material are provided at opposite ends ofthe inner peripheryofeach drum ring 15.The inner periphery ofthe support rings 17arein contactwith the outer periphery ofthe hollow shfat 1. At least one pair of support rings 17 has a projecting portion 17a projecting from the corresponding end surface of the drum ring 15. Thus, adjacent drum rings 15 are held rotatably as spaced at a predetermined distance on the outer periphery ofthe hollow shaft 1. Since adjacent drum rings 15 are in contact with each other viva the support rings 17, the frictional forces produced on their mating end surfaces are low.Therefore, even with a closely juxtaposed arrangement of a plurality of drum rings 15 between a pair of positioning rings 1 6to be described later, there is no possibility of generation of a greattake-uptorque errorthatwould otherwise result from frictional forces on end surfaces ofdrum rings. The pairofsupport rings 17 supporting each drum ring 15may be replaced with a singlesupportring.

The plurality of drum rings 15 arejuxtaposed between the pair of positioning rings 16 which are secured by the screws 18to the outer periphery ofthe opposite end portions ofthe hollow shaft 1. One ofthe pair ofthe positioning rings 16may be replaced with an increased-diameter end portion of hollow shaft 1. In this case, one end of the juxtaposed arrangement ofthe drum rings 15 is positioned by the increased-diameter end portion, while the other wend of the arrangement is positioned by one positioning ring 16 which is detachably mounted on the hollowshaft 1. The outer periphery of each drum ring 15 is provided with a plurality of (inthis embodimentthree), radially uniformly spaced-apart core-locking mechanism 14.Each core-locking mechansim 14 consists of a circumferential groove 13 having a sectional profile like a dove-tail and a steel ball 11 received in the groove 13 for rolling in the groove 13 in directions perpendicularto the axial direction ofthe hollowshaft 1. The ball 11 is fitted in the groove 13fromthe shallow bottom end thereof, and is then retained in the groove 13 by providing a retaining pin 12 orthe like adjacent to the shallow bottom end ofthegroove 13.

In this embodiment, three drum rings 15 are provided for driving each core C. With the instanttype of sheet take-up shaft, the number of drum rings and the drive force for driving each core Care increased with increase in the width of the sheet to be taken up.

To drive this embodimentofthe sheettake-up shaftfortaking up sheets on cores C, the airtube 10exten- ding in the hollow shaft 1 is preliminarily expanded by supplying compressed air undera controlled pressure according to the required take-upforce into the airtube l0through the airsupply duct 9. As a result,the plungers6 are pushed outwardly. The inner periphery ofthe drum rings iSis thus urged by the outer end 6b ofthe plungers 6with aforce corresponding to the expanding force applied to the airtube 10. Consequently, the hollow shaft 1 is made integral with the drum rings 15, and rotation oftheformer is transmitted to the latter.Then, the hollow shaft 1 is driven to cause rotation ofthe drum rings 15 in unison with the hollowshaft 1.Atthis time, the core-locking mechanisms 14 provided on the outer periphery ofthe individual drum rings 15 are operated. More specifically, each steel ball 11 is moved along the associated groove 13 toward the shallow bottom end thereof. This movement of the ball increases the extent to which the ball projects from the outer peripheryofthe drum ring.Theforce of contact between the ball and inner periphery of core Cthus is progressively increased. Eventually, core C becomes rotated in unison with the associated drum rings, whereby the sheet is taken up on core C. It is possible to control the torque transmitted from the hollow shaft being driven to the drum rings.This means that it is possible to control the frictional force acting between the plungers and the drum rings through control of the air pressure introduced into the airtube 10. Further, each drum ring 15 being driven is supported on the outer peripheryofthe hollow shaft 1 by a pairofsupportrings 17. Therefore, the drum rings 15 can be held coaxial with the hollow shaft 1 irrespective ofthe increase in the weight of the sheet rolls being wound.

The function ofthe core-locking mechanism 14will now be described in detail. As the drum rings 15with core C fitted thereon are relatively rotated (clockwise in Figure 2 in this embodiment), each ball 11 is moved along the associated groove 13 toward the shallow bottom end thereof and thus progressively projects from the outer periphery ofthe associated drum ring 15,thus pushing the innersurface of core Coutwards.The core thus is secured to and rotated in unison with drum rings 15. Further, when the core is removed, the balls 11 will not detach from the grooves 13 because the grooves 13 have a sectional profile resembling a dovetail and the retaining pin 12 is provided at the shallow bottom end ofthe groove 13.Further, the balls 11 ofthe locking mechanisms 14can also serve as rollers in the axial direction ofthetake-up shaft to permitsmooth installation and removal ofthe cores on and from the shaft.

The pair of positioning rings 16 provided adjacent to the opposite ends of the juxtaposed arrangement of drum rings 15 prevent deviation thereof in the axial direction during the take-up operation. In addition, the positioning rings 16 may be displaced in the axial direction by loosening the screws 1 foraxiallydisplacing thejuxtaposed arrangement ofthe drum rings 15. This may be doneforthe purpose of varying the position of contact between the inner periphery ofthe drum ring 15 and the outer end 6b ofthe plungers 6 in theaxial direction. By so doing, it is possible to cause uniform wear of the entire inner periphery of the individual drum rings and thus eliminate fluctuations inthefrictional force between the drum rings plungers.

To replace worn-out plunger 6, one of the pair of positioning rings 16 is unlocked with respect two the hollow shaft 1 and then displaced axially to an extent corresponding to about one drum ring. Then drum rings upto one corresponding to the plungerto be replaced are displaced likewise. When the plunger in question is exposed, the retainer ring 5 is removed from the associated through-hole 3. Now, the plunger can be readily taken out from the hole for replacement. In this connection, it is advisableto have the opposed end 17b surfaces ofthe pair of support rings 17 tapered inwardly.In this case, even if an outer end portion ofthe plungers6 projects from the outer periphery ofthe hollow shaft 1, the drum rings can be similarly moved axially by depressing the projecting plungers with the cam action ofthetapered end surfaces ofthesupport rings. As an alternative, a weak spring means may be provided between the retainer ring Sand the flange 7 of the plunger 6 such that the plunger is biased toward the center of the hollow shaft 1 and held retracted into the shaftwhile no pressurized air is supplied to the airtube. This arrangement also facilitates the axial movement of the drum rings. Further, the retainer rings may be dispensed with, if necessary, because the plunger will not be detached from the through-hole in the hollow shaft unless the drum ring is removed.

Figures 4 and 5 illustrate a second embodimentofthetake-up shaft according to the invention. Inthe preceding embodiment,the airtube 10 is expanded to causethe plungers 6to urgethe drum rings 15. In the instant embodiment, each plunger6 has a piston provided on the innerside oftheflange7, and afluid pressure supplied to the hollow portion 1a of the shaft 1 directly causes the plungers 6 to urgethe drum rings 15. More specifically, the wall surface ofeach through-hole3 provided in the peripheral wall ofthe hollow shaft 1 has the inner projection 4 provided atthe inner end, and the retainer ring 5 removablyfitted inthe through-hole 3 adjacenttothe outer end thereof has an innerannulargroove, in which an O-ring isfitted.The plunger 6 is inserted in thethrough-hole 3 with its outer end portion 6b projecting from the retainer ring 5.

The piunger6 has a piston 20 provided on the inner side oftheflange7. Piston 20 has substantially the same diameter as the diameter ofthethrough-hole3. Its outer periphery is formed with an annular groove, in which an O-ring 21 is fitted. The hole 3 serves as a cylinder, and compressed air supplied to the interiorofthe hollow shaft 1 enters the hole 3through an inlet3a to urge the piston 20. As a result, the outer end 6b ofthe plunger6 is caused to urgethe inner periphery ofthe drum ring 15which is looselyfitted on the outer periphery ofthe hollow shaft 1 thus making the drum ring 15 integral with the hollow shaft 1.

In this embodiment, the outer periphery ofthe drum ring 15 has a plurality of radially uniformly spaced- apart, circumferential inclined grooves 13. The rollers 11 held by a roller holder ring 1 1a are provided in respective circumferential inclined grooves 13. The rollers 11 constitute core-locking mechanism 14together with expansible ring 18 provided on the inner periphery of core C. As the hollow shaft 1 is rotated, each roller 11 is moved along the inclined groove 13 toward the shallow end thereof. The extent, to which the roller 11 projects from the drum ring 15, is thus progressively increased to cause an expansible ring 19 to expand and urge the inner periphery of core C. The core is thus secured to the hollow shaft.Through control ofthe pressure ofthe pressurized fluid supplied to the hollowshaft interior, the force with which the drum rings are urged by the plungers, i.e., the frictional force, can be controlled to control the torque transmitted form the hollow shaft to the drum rings with the driving ofthe hollow shaft.

Worn-out plungers 6 may be replaced in the manner as described in connection with the previous embodiment. That is, one of positioning rings 16 is loosened and axially displaced, and the drum rings up to the one corresponding to the plungerto be replaced are also axially displaced. Then the retainer ring is removed, and the plunger is taken out for replacement. The plunger may be formed integrally with or separately from the piston.

With this embodiment of the sheettake-up shaft, the pressurized fluid for controlling the torquetransmit- ted to the drum rings is supplied from a hollow shaft drive mechanism, which is not shown but is provided on the left side of the hollow shaft in Figure 4.

Further, after slit sheets have been taken up, the sheet take-up shaft with the sheet rolls is withdrawn in the axial direction from its set position for the take-up. Then, the sheet rolls are taken out, and a core or cores held in a core feeder are supplied to set positions. Thereafter, the take-up shaft is returned to the set position, whereby the cores are automatically installed. For installing core C on the sheet take-up shaft at an accurate set position thereof, a spacer 22 is provided and held between core C and a core positioning ring 23 against axial movement. To this end, the other end ofthe take-up shaft is supported by a center cone 24 rotatably supported in the bearing 2.To permit automatic locking and releasing of the core positioning ring 23 with respect two the take-up shaft, the end of the hollow shaft is provided with a radially expansible mechanism.

The radially expansible mechanism consists of a plurality of radially spaced-apart pistons 27 provided in an end portion ofthe hollow shaft 1 and an expansible ring 26 with a gap fitted on the outer periphery ofthe hollow shaft portion provided with the pistons 27. The plurality of pistons 27 can be pushed radially outwardly by pressurized fluid supplied through a pressurized fluid supply line 25, which passes through the rotaryjoint 8 provided at an end of the center cone 24 and extendsthrough the center thereof, whereby the expansible ring 26 is expanded to lockthe positioning ring 23 which is positioned on the outer periphery of the expansible ring 26.

It will be understood from the above description ofthe embodiments ofthe take-up shaft according to the invention that, each drum ring can be held coaxial with the hollow shaft by the support rings irrespective of the increase ofthe sheet roll weight or area ofthe drum ring inner periphery. Thus, it is possible to obtain high quality sheet rolls. In addition, the position of contact between the plunger and the drum ring inner periphery can be varied within a certain range. It is thus possible to suppress or avoid local wear of the drum ring inner periphery, thus reducing fluctuation in thetake-upforce applied to the individual drum rings and extending the life thereof.Further, the plungers are completelysafefrom falling into the interiorofthe hollow shaft, and it can be set in and taken outfrom the through-hole from the outer periphery side ofthe hollow shaft. Thus, the plungers can be readily assembled and replaced. This means that the replacement of the drum rings with those of a different size for cores of a different size can be readily accomplished with the take-up shaft held mounted in a slitter/rewinder.

One mode of operation oftaking up slit sheets with a slitter/rewinder employing the sheet take-up shaft according to the invention will now be described with reference to Figure 6.

Sheet S paid offmain sheet roll So byfeed rollers 33 driven byafeed-out motor M1 is slit by a slitter35into a pluralitvofslitsheets,which are taken up on a take-up shaft 32 driven by atake-up motor M2 to form sheet rolls R. Duringthetake-up of the slit sheets,thewinding hardnessthereof is controlled by movabletouch rollers 34 urged againstthesheet rolls R being wound.

The feed-out motor M1 may be a variable speed motor or a constant-speed motor provided with a con tinuousspeed change unit. As variable speed motor may be used a DC motor, an induction motorwith an inverter, an induction motor with an electromagnetic coupling, an oil hydraulic motor, etc.

The sheetfeed speed is gradually increased at the start of paying off sheet S from the sheet roll So, and it is also gradually increased and reduced at the start and end oftaking up slit sheets on the take-up shaft. Otherwise, it is held at a constant speed. The speed change pattern is preset in a speed setter 55 associated with the feed-out motor M1. The sheet feed speed may be setforthe entiretake-up process or only for speed increase and decrease periods. The electric signal ofthe speed setter is fed to a speed controllerfor motor M1 for speed control.

Either a signal from speed detector 54 provided onthefeed-outmotorM1 ora signal obtained through direct detection ofthe sheet speed is fed to a speed controller53forthetake-out motor M2 when the speed of the sheet S being paid off is being increased or reduced or is constant To speed controller 53 is also fed a signal from a take-up amount detector47. The take-up amount detector 47 detectsthe amount of sheettaken upfromthe angle of a support arm ofthetouch roller34. The required revolving rateV/TrD of thesheet roll R thus is calculated from thespeed V ofthe sheet Sand the diameter D of the sheet roll R. The take-up motor M2 is controlled through a drive speed control mechanism according to the value obtained by adding a value corresponding to an adequate amount of slip to the calculated revolving rate or by multiplying the revolving rate by a factor representing the slip. Means for increasing the speed of a drive shaft31 to an extent corresponding to a slip maybe provided either in an electric control unitorin a mechanicaltorquetransmission unit.

The take-up motor M2, like the feed-out motor M1, may be a variable speed motor or a constant-speed motor with a continuous speed change unit. Where take-up motor M2 is a variable-speed motor, e.g., a DC motor, a stationary speed controller is used as the drive speed control mechanism to control the revolving rate according to an electric signal from the speed controller 53.

The take-up amountdetector47 may be ofanywell-knowntype. For example, it may be one in which the angle of a support arm ot the touch roller 34 is detected with a potentiometerorthe like, or it may be one which detects the roll diameter from the length ofthe supplied sheet. Further, it may be one which detects the roll diameter without contact with the sheet roll. The diameter of the wound sheet roll may be calculated from the detected value.

With the conventional take-up shaft with drum rings, onlythefrictional torque between the shaft and drum rings has been considered, and the speed of the shaft has been set to a high speed or slowed down by the operator when it increases excessively. In such case, heat generation in the frictional section is not uniform, resulting in variations in the coefficient offriction, and thus has an adverse effect on the frictional torque, which is very important. According to the invention, the shaft drive speed is set with reference to the amount ofsheettaken up such thatthe revolving rate of sheet roll being paid off is slightly higherthan the sheetfeed speed, that is, the slip between hollowshaftand drum rings is held ata slight value at all time.The heat of friction is thus reduced so as to greatly extend the life ofthe frictional section and save time and labor forthe maintenance and repair. Further, since the coefficient of friction can be made constant, the precision of control ofthetake-uptorque according to the friction can be increased. Meanwhile, an output signal from the take-up tension controller 46 is coupled to frictional force controller 45 for conversion to a necessary oper- ational quantity, i.e., fluid pressure, which is coupled to the sheet take-up shaft32.

Figure7 is a block diagram showing an exampleofatake-uptension controller46. The required take-up amountforthe take-up tension pattern corresponding to the material of the sheettaken up, take-up con- ditions, etc. is set in a take-up amount versus take-up tension setter 41 by operating a variable resistor knob, a digital switch, a keyboard, etc. Frictional force controller45 calculates a take-up tension signal corresponding to the instantaneous take-up amount according to atake-up amount signal suppled from the take-up amount detector 47 mentioned above and the setting signal from the take-up amountversustake-uptension setter 41 .Theformula for calculation of the instantaneous take-up tension is adopted according to design con- ditions. For example, when the take-up diameter is detected as the take-up amount, the instantaneoustakeup tension F can be given as

where R isthetake-up diameter, Rmin is the core diameter, Rmax is the final take-up diameter, Fo is the preset take-up tension at the start oftake-up, and P is the tension reduction factor.Operatonal quantity control unit 42 calculates the necessarytake-uptorque, and also an operational quantity for obtaining the desired frictional torque, from the setting signal from the take-up amount versus take-up tension setter 41 and the take-up amount signal from the take-up amount detector47 and amplifies the result. The output of oper ational quantity control unit 42 is fed to the frictional force controller45 for conversion to the required oper ational quantity, which is coupled to thetake-upshaft. In the embodiment ofthetake-up shaftshown in Figure 1,the airtube 10 constitutes an expansion mechanism, and the air pressure constitutestheoper ational quantity.In this case, thefrictional torque transmitted to the drum rings is determined by theforce with which the plungers of thetake-up shaft are urged, which force is determined by the pressure of air supplied to the airtube. The relation between the supplied air pressure (i.e., operational quantity) and the transmitted torque can be derived from the dimensions, material, etc. of the sheet take-up shaftandex- pressed as a formula. A more accurate formula may be obtained by determining constants by empirically obtaining supplied air pressure versus transmitted torque characteristics. Further, the torque required to be transmitted can be obtained from the take-up diameter and take-up tension.The supplied air pressure, there- fore, generally can be expressed as a function of variables representing the take-up amount and take-up tension and including the coefficient offriction and other constants. Fluid pressure calculator 43 may be provided with the function of air pressure calculation using this formula. Where a constant in theformula varies with the material, dimensions, etc. of th sheet, a constant setter may be provided. The fluid pressure signal (i.e., required operational quantity signal) obtained from thefluid pressure calculator43 is amplified in an amplifier44to be fed to the pressure regulator45.The pressure regulator45 provides air under pressure based on the amplified fluid pressure signal,the air being supplied to the airtube inthetake-up shaft 32 through thetube and rotaryjoint. Thus, the operator need onlyseta take-up amountversustake-uptension pattern in the setter 41, and then the frictional torque ofthe sheet take-up shaft can be accuratelycontrolled automatically so asto provide a take-up tension corresponding tothetake-up amount. It is thus possibleto obtain high qualitytaken-up sheet rolls without need of any skill on the part of the operator.

Figures 8 and 9 show examples of sheet take-up shaft frictional torque controllers applied to the casewhere the take-up tension is controlled by the sheet take-up shaft according to the invention. In these instances, high quality sheet rolls can be obtained through control ofthetake-uptension ortake-uptorque according to the take-up amount. The relation between the take-up tension ortake-uptorque and take-up amount can be expressed either as a graph or as a formula.

In the example of Figure 8, the required frictional torque ofthetake-up shaft 32 calculated by a small computerfrom a presettake-up tension versus take-up amount relation and the detected drivetorque coupied to the drive shaft 31 as detected by a torque detector 48 are compared forfeed-backcontrol.

In the example of Figure 9, a take-up tension calculator49 obtains the take-uptension by dividing the detected torque bythe sheet roll diameter. The calculated take-up tension is compared with a presettension in a comparator50. The output of the comparator 50 is coupled to the frictional force regulator45 through the frictional torque controller 43. In this case, it is possible to set a take-up torque versus take-up amount relation.

The torque detector 48 may be one which detects the twist of a torsion shaft provided in a transmission mechanism for driving the hollow shaft. Alternatively, it may be one which detects a belt tension in a belt transmission mechanism or a reaction force acting on a torque detection gear in a geartransmission mechanism.As a further alternative, it may be one which detects a reaction force acting on a hollow shaft drive motor. Where the motor is a DC motor, it is possible to detect the motor current and use the detected current as a torque signal.

In either of the cases of Figures 8 and 9, the feedback control cannot be accomplished for each of a plurality of slit sheet rolls taken on a common take-up shaft because the individual taken-up sheet rolls do not have equal diameters at all times. However, substantially effective feedback control can be obtained by taking the sum of the frictional torques between the shaft and the drum rings forthe individual taken-up sheet rolls and comparing the sum with the actual torque of the common drive shaft. The sheet take-up tension control thus can be carried out more accurately.

Figures 10 and 11 showexamples of a sheettake-up shaftfrictional torque controller, in which thedrive torque of the drive shaft is also controlled according to a preset tension ortorque versus take-up amount relation to preventexcessivetorque as in the prior art sheet take-up shaft.

Figure 10 shows a basic arrangement Atake-up torque controller 42 shown enclosed by a phantom line receives data on the prevailing take-up amount from take-up amount detector47 and data on the required tension from tension versus take-up amount relation setter 41 and calculates the required take-up torque corresponding to the sheet width. As in the previous embodiments or the examples of Figure 8 and 9, a friction regulator, e.g., a pressure regulator, in a mechanism for transmission offriction between the hollow shaft and the drum rings is controlled. It is of course possible to use a take-up torque versus take-up amount relation setter.According to the invention, the drive torque ofthe drive shaft is also controlled according to the calcuiated take-u p torque obtained from a separately provided take-uptorque controller or a common controller. More specifically, the drive motor may be provided with a torque regulator, e.g., magnetic powder clutch, and the magnetic powder clutch may be controlled such that the transmitted torque is equal to or slightly higherthan the calculated take-uptorque. The magnetic powder clutch is convenient as atorque regulator. From the standpoint of energy saving, however, a DC motor or induction motor with an inverters preferabaly used.

Where both the drive torque ofthe drive shaft and frictional torque offriction between the shaft and drum rings are simultaneously controlled, the friction regulator can control the friction between the shaft and drum rings to zero slip through control of the two torques noted above to the desired take-up torque. In this case, each slitsheet can betaken up with the required torque with the hollowshaft and drum rings rotated together just as in the ordinarptake-up shaft. An advantage ofthe invention, however, is that upon occurrence of a difference in the taken-up slit sheet roll diameter a slip of a greater diameter sheet roll is produced.It is thus possible to continue simultaneoustake-up of a plurality of slit sheets even ifthe taken-up sheet rolls being wound have different diameters. The slip that is produced in this case is very small compared with the slip in the case ofthe prior arttake-up shaft.

However, in case where the slip is very small so that the friction between the hollow shaft and drum rings is liable to become a static friction or a dynamicfriction, a certain constant slip may be provided by controlling the drivetorque on the side of the drive shaft to be slightly higherthan the desired torque in the tension control. In the example of Figure 10 the drivetorque of the drive shaft and fructional torque offriction be tween the hollow shaft and drum rings are controlled by the common torque controller 42. However, it is possible to provide an exclusivetorque controllerfor each torque.

Figure 11 shows a more practical example. In this instance, a pressure regulator using an airtube 36 is provided as a friction regulatorforthe drive shaft. The drive motor is driven at the required speed (take-up speed) and with the required torque by the drive motor controller 53, which receives a line speed signal, a take-up amount signal and a take-up torque signal. Torque detector 48 is also provided forfeedbackcontrol.

In this example the drive torque of the drive shaft is controlled by feedback control, differently from in the examples of Figures 8 and 9 in which the frictional torque isfeedback controlied.These feedbackcontrols may be suitably combined depending on the condition of application of the invention.

It isto be understood that not only the friction between the hollow shaft and the drum rings is controlled according to the computer-calculated take-up torque, but the drivetorque ofthe shaft is controlled to a calculated value corresponding to a presettension ora slightly greatervalue. Thus, the slip between the hollow shaft and drum rings may be unnecessary or very slight. The actual take-up tension thus can be stabilized without being adversely affected by the friction.

Claims (8)

1. Atake-up shaft for a sheet rewinder comprising: a hollow shaft having a plurality of through-holes formed in the peripheral wall at predetermined intervals in the circumferential and axial directions, the wall surface defining each said through-hole having an inner projection provided atthe inner end of the hole; a plurality of drum rings rotatablyfitted on said hollowshaftto closethe outer open ends of said through- holes, the inner periphery of said drum rings serving as a frictional surface;; plungers each inserted one in each said through-hole, each said plunger having a least one hook portion greater in size than the inner diameter of said inner projection, support rings provided at the opposite ends of the inner periphery of said drum rings,the inner periphery of said support rings being in contact with the outer periphery of said hollow shaft; and urging meansforoutwardly urging said plungersthroughthe interiorofsaid hollow shaft.

2. The take-up shaft according to claim 1,wherein a retainer ring is provided in each said through-hole adjacent to the outer open end thereof, an outer end portion of each said plunger has a diametersmallerthan the diameterofthe opening of said retainer ring, each said plunger is incapable of clearing the opening of said retainer ring even when it is most retracted into said through-hole, and said hook portion of each said plunger is a flange formed on the outer periphery of said plunger.

3. The take-up shaft according to claim 1,wherein said urging means includes an expansible airtube provided in said hollow shaft and means for supplying compressed air into said expansible airtube, said plungers being outwardly urged with expansion of said expansible airtube.

4. The take-up shaft according to claim 1, wherein said urging means includes pistons each provided on a portion of each said plunger positioned in each said through-hole on the inner side of said flange and means for supplying compressed air into the interior of said hollow shaft, said plungers being outwardly urged with outward movement of said positions caused by compressed air forced into said through-holes.

5. The take-up shaft according to claim 1,wherein at least one of said support rings provided atthe opposite ends ofthe inner periphery of each said drum ring has a portion projecting axially from an end surface of said drum ring.

6. The take-up shaft according to claim 1, which further comprises positioning rings fitted on said hollow shaft adjacent to the opposite ends thereof to retain said drum rings on said hollow shaft.

7. The take-up shaft according to claim 1,wherein said urging means includes: a take-up amount detector; atake-up amountversus take-uptension relation setterforsetting a take-up amountversustake-uptension characteristic pattern and calcuiating the instantaneous take-up tension according to a take-up amount signal from said take-up amount detector; and take-up tension control means having an operational quantity controllerfor calculating an operational quantityforobtaining a desiredtake-uptorquefrom said take-up amount signal and a signal representing the calculated instantaneoustake-uptension and amplifying the calculated operational quantity and a frictional force controllerfor converting an output signal from said operational quantity controller into a different operational quantity.

8. Atake-up shaft for a sheet rewinder substantially as herein before described with reference to and as shown in the accompanying drawings.