US 3409243 A
Description (OCR text may contain errors)
Nov. 5, 1968 J. H. WASSERLEIN 3,409,243
' WINDING APPARATUS Filed Feb. 8, 1965 5 Sheets-Sheet l INVENTOR. JOHN H. WASSERLEIN ATTORNEY Nov. 5, 1968 J. H. WASSERLEIN WINDING APPARATUS 5 Sheets-Sheet 2 Filed Feb. 8, 1-965 H E mm H F SE TD N GN ET NU Ts 3320525 mm 1 w "a m b P 5 O B TORQUE E U Q R o T w T U L C ITENSION(8 N IAL TORQ E LENGTH WOUND z mDOmOk WEB TORQUE INVENTOR. JOHN H. WASSERLEI N ATTOR Nov. 5, 1968 H, WASSERLEW 3,409,243
WINDING APPARATUS Filed Feb. 8, 1965 5 Sheets-Sheet 5 INVENTOR. JOHN H. WASSERLEI N ATTORNEY .1. H. WASSERLEIN Nov. 5, 1968 5 Sheets-Sheet 4 Filed Feb. 8, 1965 INVENTOR. JOHN H. WASSERLEI N Nov. 5, 1968 J. H. WASSERLEIN 3,409,243
WINDING APPARATUS Filed Feb. 8, 1965 5 Sheets-Sheet 5 CLUTCH (1') CJ g 0 2 FT mm 2000 F lg. l2 2 LENGTH wouwo HUN 0s) 0 0: O
JOHN H. WASSERLEIN BWJ;
United States Patent Office 3,409,243 Patented Nov. 5, 1968 3,409,243 WINDING APPARATUS John H. Wasserlein, Clarksville, Tenn., assignor to Scott Paper Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Feb. 8, 1965, Ser. No. 431,016 7 Claims. (Cl. 242-64) ABSTRACT OF THE DISCLOSURE High speed web winding apparatus is disclosed which is adapted for turret type winders to control tension applied to the web being woundfiThe apparatus responsively adjusts the torque transmitted by a drive motor to a winding mandrel to reflect various changing torque conditions existing during the progress of the wind of a web into a roll upon'a core carried on the mandrel. In addition to a rotatable mandrel on which the web is to be wound, a drive means, and a clutch for transmitting torque from said drive means to said mandrel, the apparatus includes means responsive to the velocity of said mandrel as a function of the square of the velocity of the mandrel and, in addition, program means responsive to the progress of a wind on said mandrel and acting on said clutch for progressively controlling the torque transmitting ability of the clutch during the web wind. For example, one embodiment of the apparatus employs means, such as the combination of a centrifugally actuated clutch system and a cam system for superimposing a program control upon the clutch system, which means cooperate to properly compensate for changing torque conditions in the winding system in order to maintain substantially constant web tension during the progress of the wind.
This invention relates to winding apparatus and more particularly to apparatus for winding lightweight webs, or tapes, at high speeds.
It is common practice in the production of lowcost roll items, such as toilet tissue, to employ high speed equipment in which the rolls are wound on a series of movable mandrels which are successively brought into winding position to commence a winding operation immediately after the completion of the preceding winding operation and without stopping or slowing the incoming web of ma terial. Attempts are constantly made to operate winders of this type at increasingly higher speeds in order to render the operation more economical. Although elaborate control systems have been developed through the years, high speed operations of such machines have always been replete with problems of web breakage, particularly when winding low strength materials, such as paper.
Obviously, web breaks occur during winding when the tension to which the web is subjected exceeds the tensile strength of the web material. In high speed winding machines it is difficult to sense the tension existing in the web during the wind, primarily because of space limitations within the machine. More commonly, a clutch is imposed between the drive and the winding mandrel to limit the amount of torque imparted to the mandrel and thereby indirectly limit the tension to which the web is subjected. The use of such a clutch offers the further advantage of permitting the mandrel to slow down during the wind as the roll grows so that the web can be wound at constant speed while the mandrel is driven from a constant speed drive. An automatic winding machine incorporating these features is disclosed in US. Patent No. 2,769,600 to Kwitek et a1.
It is the principal object of this invention to improve the operation of the aforementioned type of winding equipment so that the winding operation may be performed at higher speeds and/or with less frequent web breakage.
I have discovered by investigation and analysis that machines equipped with clutches for driving the winding mandrels subject the web to large variations in tension during the course of the wind. I have further discovered that these extreme variations of tension in the web are the result of the machines failure to take into account and compensate for the various torque conditions existing during the wind. In particular, such machines, in the past, have disregarded or failed properly to take into account the inertial torque caused by deceleration of the winding mandrel and the wound web during the wind. It is, therefore, another object of this invention to provide means for varying the torque transmitting ability of a winding clutch to vary the applied torque in inverse ratio to the varying inertial torque present in the winding system. Inertial torque is the result of deceleration of the rotating system and is a function of the square of the velocity of the system. This invention, therefore, contemplates varying the torque transmitting ability of the clutch indirectly with the changes in the square of the angular velocity of the winding mandrel. For this purpose the invention employs means responsive to the angular velocity of the mandrel for reducing the torque imparted to the mandrel in inverse ratio to a function of the square of the angular velocity.
It is well known that if any degree of uniformity is to be maintained in the tension of the wound roll in a center drive winding operation it is necessary to increase the torque applied to the winding mandrel as the roll of material grows to offset the increasing moment arm through which the torque acts on the web being wound. In various prior art machines centrifugal force responsive clutch elements have been employed to progressively increase the torque imparted to the winding mandrel during the web wind. See, for example, US. Patent No. 2,901,192 to Nystrand. The use of a centrifugal clutch for this purpose has a number of drawbacks and limitations. The principal deficiencies are that the use of such a clutch does not produce the precise torque program required and is limited to the particular operating speed for which the clutch is designed. Any departure from the design speed results in the clutch transmitting more or less torque than is desired for winding at constant web tension.
It is a further object of this invention to program the torque imparting ability of a winder clutch to increase its torque imparting ability progressively as more web material is wound and the size of the wound roll grows. This program can, in accordance with this invention, also take into consideration other factors affecting web tension during the wind, such as torque conditions resulting from friction and windage in the system as well as such differences in torque profile characteristics as may exist between the actual intertial torque profile existing for the system and the torque profile of the speed responsive clutch control.
The principal features, then, of this invention reside in modifying the torque transmitting ability of a winder clutch, first, in accordance with changes in the square of the velocity of the winder mandrel and, second, in accordance with a predetermined program during the progress of the wind from start to finish. This combination of features of the invention permits webs to be wound either with constant tension throughout the wind or with any desired tension profile through the wind.
It is a further object of this invention to improve the reliability of winders employing a clutch by reducing the tendency for the clutch to undergo excessive slip prior to commencement of a web wind. In prior machines such slippage resulted in the winding surface of the mandrel not being brought up to web speed at the time the web 3 was transferred to the mandrel and the transfer could not be accomplished smoothly. This object is achieved by designing into the programming means for the clutch an override, or overload, to substantially increase the torque transmitting ability of the clutch and prevent slippage prior to web transfer.
These and other objects, advantages and features of the invention can be better understood from the following detailed description of the invention wherein reference is made to the accompanying drawings, in which:
FIG. 1 is a diagrammatic sectional view taken near one end of -a winding machine of a type to which this invention is applicable;
FIG. 2 is a graphic illustration of various torque effects present and tension forces-experienced by the web during a wind on a typcial prior art machine operating at the upper limit of its operating speed;
FIG. 3 is a graphic illustration similar to FIG. 2 illustrating conditions experienced in a winding machine incorporating this invention and operating at a comparable speed;
FIG. 4 is a sectional view through a clutch for one of the mandrels of the machine illustrated in FIG. 1;
FIG. 5 is a transverse sectional view of the clutch taken as indicated by line 55 in FIG. 4;
FIG. 6 is an enlarged sectional view of a pad arm component of the clutch shown in FIG. 4;
FIG. 7 is a perspective view of a clutch adjusting sleeve employed in the clutch of FIG. 4;
FIG. 8 is a transverse sectional view taken as indicated by line 88 in FIG. 4 and illustrating an operator adjustment for the clutch;
FIG. 9 is an elevation view of one end of the turret assembly of the machine of FIG. 1 with portions of the turret broken away to illustrate various components of a clutch programming control;
FIG- 10 is a sectional view taken as indciated by line 10-10 in FIG. 9;
FIG. 11 is an elevation view, partially in section illustrating a modified clutch incorporating this invention; and,
FIG. 12 is a graphic illustration of the effect changing winding velocity has on torque required to be transmitted by a clutch in order to maintain constant tension in the web. a
FIG. 1 illustrates a typical continuous winding machine employing a plurality of winding mandrels 11 rotatably carried by the arms of a turret 12 which, in turn, is rotatably supported by a shaft 13. Suitable means (not shown) are provided for rotatively indexing turret 12 in clockwise direction for bringing succeeding mandrels 11 into winding position adjacent a rotatably mounted bed roll 14 over which a web 15 to be wound is fed. The web 15 may be directed to bed roll 14 through perforator rolls indicated at 16 and 17 and a feed roll 18. During normal operation bed roll 14 is driven at a substantially constant velocity and as a roll of web material is completed on one of the mandrels 11 that mandrel is moved away from the bed roll and the succeeding mandrel is indexed into position near the bed roll, the web is severed and the leading edge of the severed web is transferred to a succeeding mandrel by suitable means, such as the retractable knife indicated at 19.
In order to insure a smooth transition of web feed from one mandrel 11 to the next mandrel and to insure continuous feed of the web 15 during the wind it is essential that each mandrel as it approaches the winding position be rotatably driven to bring its winding surface up to the surface speed of bed roll 14 and subsequently, during the wind, be permitted to slow down to compensate for the growth of the roll being wound on the mandrel. The drive means illustrated in FIG. 1 is similar to that disclosed in the aforementioned Patent 2,769,000 and includes a moving flexible belt 21 positioned to engage a clutch mechanism 22 carried by each of the mandrels 11. It will be noted that drive belt 21 engages a clutch 22 only when the mandrel for that clutch is approaching bed roll 14 or is in the vicinity thereof during the web wind. Belt 21 may be driven by any suitable means, such as the pulley and belt drive 23, and a drive motor 24. The other moving components of the winder, such as turret 12 and bed roll 14 may also be driven from motor 24, but if driven by other motive sources their movements should be synchronized so that drive belt 21 is moving at a linear speed which will cause the surface velocity of a driven mandrel 11 to match the surface velocity of bed roll 14.
Winding machines such as that illustrated in FIG. 1 often have incorporated therein slip clutches which permit the winding mandrel 11 to slow down during the web wind, notwithstanding the fact that drive belt 21 is propelled at a constant linear velocity. So called, constant torque clutches of this type limit the maximum amount of torque transmitted to their winder mandrels and are supposed to prevent the web from being subjected to excessive tension during the wind. In reality such clutches are ineffective to compensate for all factors influencing web tension and at higher winding speeds are totally ineffective to prevent web breakage.
Winding conditions FIG. 2 illustrates what has been determined by laboratory investigation and analysis to be typical torque conditions and web tension conditions existing during the winding of a series of rolls of toilet tissue or a log of such tissue in a winder employing constant torque clutches. The line identified as Clutch Torque represents the torque which is actually transferred through the clutch 22 and applied to the winding mandrel 11. For reasons which need not be discussed here there is a slight drop in the torque applied to the mandrel by the clutch at the beginning of the web wind. For all practical purposes, however, the torque transmitted is essentially constant throughout the wind. It will be noted that the web tension changes considerably during the web wind and is highest at the beginning of the wind (see curve labeled Web Tension). In the particular illustration of FIG. 2 the tension in the web at the beginning of the wind approaches 20 lbs., which is near the 20 to 30 lbs. tensile strength possessed by a perforated web of tissue paper for winding 20 rolls of toilet tissue. Consequently, any slight malfunction of the machine or non-uniformity of thickness or strength of the web can result in breaking the web at or shortly after the beginning of a wind.
FIG. 2 also illustrates one of the factors which contribute to high web tension at the beginning of a wind with existing windingequipment. Note the form of the curve identified as Inertial Torque. This torque acts in the direction of rotation of the rotating mandrel and is the result of deceleration of the mass of the mandrel and the web being progressively wound thereon. It will be noted that the inertial torque is greatest at the beginning of the web wind when the mandrel is turning at very high rotative speed and is undergoing its maximum deceleration. The inertial torque of the wound web material, the mandrel and associated rotating equipment is a function of the square of the angular velocity of the rotating system as expressed in the following equation:
paga z wherein,
C is a constant for the particular system, I is the moment of inertia of the mandrel and clutch,
I is the moment of inertia of the web wound,
R is the instantaneous radius of the building roll, and
w is the angular velocity of the rotating system.
Although I and R are both increasing during the wind, their relative positions in the equation are such that the combined term within the brackets is substantially constant.-It therefore follows that T is essentially directly proportional to 40- The ordinary clutch is notcapable of compensating for the variation in inertial torque during the wind. This is particularly true as winding speeds are increased because of the marked effect the higher speeds have on increasing initial inertial-torque. This-accounts for the experience with prior machines that as higher operating speeds are attempted more frequent breakage of the web material is encountered.
1 FIG. 2 further illustrates the other torque factors which have been determined to be present in the winding of weak webs at high speeds. The line identified as Friction Torque. illustrates the magnitude of the effect mandrel friction and windage have in tending to slow the mandrel and the web wound thereon. The winding system is held in equilibrium by the Web Torque, which simply is that torque which is imposed on the rotating mandrel by tension in the web and which equals the algebraic sum of the clutch torque and the inertial torque, less the friction torque.
FIG. 3 illustrates graphically the more favorable winding conditions which can be practiced utilizing the present invention. It will be noted that in this example the tension is held substantially constant at approximately 8 lbs. from the beginning to the end of the wind. The inertial torque and the friction torque exhibit substantially the same magnitudes and behaviors as in the system illustrated in FIG. 2. In this instance, however, the clutch torque is programmed to produce a constant tension wind and it will be noted that this clutch torque profile is substantially different from the clutch torque profile of the prior machines represented by FIG. 2. It will also be noted that the web torque follows a smoothly increasing curve in the negative direction as would be expected in winding a web on a growing roll at constant tension.
Programmed centrifugal clutch The web wind conditions illustrated graphically in FIG. 3 can be reproduced in accordance with this invention by means of a centrifugal releasing clutch having imposed thereon a programmed control which modifies the inherent torque imparting ability of the clutch in accordance with the progress of the wind A preferred embodiment of this clutch is illustrated in FIG. 4 and is identified generally by reference numeral 22. There is one such clutch 22 for each winding mandrel 11 and each clutch is carried by its mandrel preferably in a location between spiders 26 and 27 of the turret 12. Spider 26 has securely clamped thereon a sleeve 28 within which mandrel 11 is free to turn in a bearing 29. An extension of sleeve 28 has rotatably mounted thereon a drive wheel, or pulley, 31. Pulley 31 is mounted on bearings 32 which enable the pulley to rotate freely on sleeve 28 and independently of mandrel 11. Pulley 31 is equipped with a V-shaped channel 33 for engagement with drive belt 21 (see FIG. 1). One end of pulley 31 has a flange extension providing a clutch face 34 which constitutes a friction surface of the clutch.
Clutch face 34 of pulley 31 is engaged by a plurality of felt friction pads 36 disposed in circular array about the clutch face. Each friction pad 36 is carried in a holder 37 having a radial support arm 38 which is pivotally mounted by means of a pin 39 in a ring 41. Ring 41 is secured to an elongated sleeve 42 which is keyed to mandrel 11 for rotation therewith. The spider-like assemblage of friction pad holders 37 is rotatable with the mandrel 11 and capable of transmitting torque forces to the mandrel 11 as a result of frictional engagement of pads 36 with rotating clutch face 34. Friction pads 36 are held in engagement with clutch face 34 by suitable biasing means preferably in the form of helical springs 43 compressively disposed betweenpad holders 37 and a backup ring 44 carried for rotation with sleeve 42, but axially slidable on sleeve 42.
Referring to FIG. 6, it will be noted that the mounting of each friction pad holder 37 is such that the combined centroid of the holder 37 radial arm 38 and friction pad 36 is displaced-longitudinally of the clutch assembly fromthe axis of mounting pin 39 so that centrifugal force acting on the pad holder 37, radial arm 38 and pad 36 at the centroid during rotation of-the mandrel 11 results in establishment of-a force couple tending to rotate the pad holder 37 in clockwise direction about pivot pin 39 in opposition to the force of compression spring 43. Thus, centrifugal force acting on each of the pad holders 37 tends to reduce the force with which the pads 36 are held against clutch face 34 as the rotational velocityof the mandrel increases. At very high speeds it is possible for the force couple acting on each pad holder 37 to completely overcome the force of its compression spring 43 and separate clutch pad 36 from clutch face 34 so that no torque will be transmitted across the face of the clutch. With this construction it is possible by careful design of the assemblage of clutch holders 37 to provide in each clutch 22 a speed responsive torque transmitting characteristic inversely proportional to the square of the angular velocity of amandrel 11 so that the clutch transmits substantially less torque when traveling at high speed at the beginning of the web wind than when the mandrel slows down as the wind progresses. Preferably, the torque profile of the centrifugal portion of the clutch is designed to be comparable to but opposite to the profile of the inertial torque of the system as illustrated by the inertial torque curve in FIG. 2.
It should be evident from the earlier discussion of FIG. 2 that there are other torque conditions acting on the winding system which are not overcome by a centrifugal clutch designed to cancel the inertial torque of the system. There are, for example, the effects of friction torque and the requirement for increasing torque as the roll grows during winding. In accordance with this invention there is superimposed upon the centrifugally actuated clutch system a program control which modifies the operation of the clutch in accordance with the progress of the wind, i.e., length of web wound. The program control accounts for the other variable torque conditions to enable the clutch to impart to the mandrel the constantly changing torque required to wind the web at constant tension. This programmed modifying means includes a cylindrical cam actuating sleeve 47 concentrically disposed about mandrel sleeve 42 and having one end connected to clutch ring 44 by means of a bearing 48. Sleeve 47 has cam surfaces 49 cut in the opposite end thereof fwhich are adapted to bear against rollers 51 carried on an operator adjustment ring 52. Throughout most operating periods of the machine ring 52 is stationary with respect to trunnion spider 27, but may be moved by the operator for making fine adjustments as is explained below.
As shown in FIGS, 4 and 7, cam sleeve 47 has an actuating arm 53 attached thereto and extending inwardly of the machine turret 12. Movement of arm 53 imparts rotation to the cam sleeve 47 and this movement is translated into axial movement of sleeve 47 by virtue of cam surface 49 riding on rollers 51. Axial movement of sleeve 47, in turn, imparts axial movement to clutch ring 44 to change the compression of clutch springs 43 to vary the effectiveness of thesesprings in biasing friction pads 36 into engagement with clutch face 34. When viewed from the right-hand end of mandrel 11 as shown in FIG. 4, clockwise movement of sleeve 47 increases the compression of springs 43 and counter-clockwise rotation of sleeve 47 decreases the compression of springs 43.
Movement of actuating sleeve 47 is effected by cam means responsive to the progress of a web wind. A preferred form of cam means for this purpose is illustrated in FIG. 9 and takes the form of a large circular cam 56 which is supported for rotation about the axis of turret 12 by means of a series of wheels 55. The outer surface of cam 56 is adapted to be engaged by follower rollers 58 7 carried at the ends of the several actuating arms 53 for the cam sleeves 47. Cam 56 has a program surface segment 59 adapted to effect movement of one actuating arm 53 in a controlled manner for the clutch 22 of the mandrel upon which a web is being wound. Cam 56 also has a high rise dwell segment 60 ahead of program segment 59 which is adapted to effect overload of a clutch 22 as the mandrel for that cam is moving into winding position to insure the mandrel being brought up to initial winding velocity.
Relative movement of cam 56 with respect to turret 12 is effected by means of a drive system which synchronizes movement of cam 56 with the amount of web material wound on the mandrel. While other drive means, such as a flexible shaft, can be used for this purpose, the drive illustrated comprises a gear 61 affixed to cam 56 and a pinion 62 carried on the shaft of a stepping motor 63 which is affixed in any suitable manner to the turret 12. Movement of cam 56 is in the direction opposite to the indexing motion of turret 12 in bringing successive mandrels 11 into winding position. When observed from the end of the machine during operation, cam 56 will appear to oscillate while maintaining the same general relationship with a fixed object on the machine.
Stepping motor 63 is driven at a rate which corresponds to the operating speed of the machine and, consequently drives cam 56 with a rotational movement corresponding to the progress of a web wind, Motor 63 is preferably energized from a pulsing system which may take the form of a switch 64 located in the vicinity of bed roll 14 and actuated by a cam 66 rotating with bed roll 14 (see FIG. 1). Electrical leads 67 from switch 64 are connected by means of a suitable slip ring assembly (not shown) to corresponding leads 67 on the stepping motor 63.
The clutch mechanism of FIG. 4 is preferably provided with an operator adjustment permitting displacement of the torque profile of the clutch 22 to higher or lower limits to enable the operator to select a more tightly wound or a more loosely wound roll in order to maintain a predetermined roll size when winding webs of different bulk. As shown in FIG. 8, this adjustment is effected by rotating adjustment ring 52 by means of a hand screw 71 passing through the ring mounting 72 and engaging a notched-out region 73 of ring 52. Sleeve 52 is maintained in contact with hand screw 71 by means of a backing spring 74 at the opposite side of the ring. Rotation of ring 52 relative to adjustment cam sleeve 47 has the effect of axially shifting sleeve 47 and changing the compression in clutch springs 43.
Operation of programmed centrifugal clutch When the machine is in operation, the turret 12 will index one of the mandrels 11 into winding position to receive the leading edge of a web being fed over bed roll 14. As the mandrel approaches winding position, the groove 33 of the clutch pulley 31 engages drive belt 21. Belt 21 is moving at a velocity which rotates clutch pulley 31 at an angular velocity which matches the surface velocity of the mandrel 11 to the velocity of the web leaving bed roll 14. During this pre-wind period it is highly desirable. that there be no slippage in the clutch 22 so that the mandrel 11 positively assumes the desired angular velocity. This condition is assured by virtue of the clutch compression springs 43 being subjected to higher than winding compression by virtue of the follower roller 58 of the actuating arm 53 of the clutch being in engagement with the high rise dwell segment 60 of the program cam 56. The cam 56 at this location is effective to rotate adjustment cam cylinder 47 to its maximum clockwise position as viewed in FIG. 9 and to thereby move clutch ring 44 to a leftmost position as viewed in FIG. 4. The compression of clutch springs 43 at this point is such as to more than overcome the centrifugal force couple acting on clutch pad arms 37, notwithstanding the high rotational velocity of the clutch and the mandrel at this point.
As the mandrel 11 reaches its winding position and web 15 is transferred to the mandrel to start the wind, cam follower 58 on clutch actuating arm 53 moves into the program segment 59 of cam 56, allowing cam cylinder 47 to undergo counter-clockwise movement to release some of the compression in clutch springs 43. This allows the centrifugal force couple acting on clutch pad holders 37 to tend to rotate the holders about their pivot pins 39 and relieve the frictional engagement between the clutch pads and the clutch face 34. As can be observed from the clutch torque curve in FIG. 3, the torque transferred to the mandrel through clutch 22 is quite low at the beginning of the wind. At this point the inertial torque of the clutch and mandrel substantially assist in winding the web 15 onto the mandrel with very little, if any, additional torque being required.
As the wind progresses and the roll of web material on the mandrel increases in size, the inertial torque decreases rapidly because of slowing of the mandrel velocity. During this period additional torque is applied to the clutch 22 because the centrifugal force couples acting on pad holders 37 diminish and the friction pads 36 are pressed into tighter engagement with the clutch face 34 by compression springs 43.
Simultaneously, as the wind progresses and the roll diameter increases, additional torque must be transmitted to the mandrel 11 by the clutch 22 to compensate for the growing moment arm through which mandrel torque is applied to the web 15. The torque transmitting ability of the clutch 22 is increased in a programmed manner by virtue of the clutch actuating arm 53 following the progressively increasing radius of program segment 59 of cam 56. The torque transmitting, or imparting, ability of clutch 22 is thus caused to follow the general profile indicated by the clutch torque curve in FIG. 3 by the combination of the centrifugal force acting on friction pad holders 37 and the programmed change of compression of clutch biasing springs 43 under control of program cam 56.
At the end of the wind web 15 is severed by the knife 19 in bed roll 14 and the mandrel 11 containing the completed roll is indexed by turret 12 out of winding position as the succeeding mandrel is brought into position. Clutch 22 of the mandrel containing the wound roll is thus moved out of engagement with drive belt 21 and this mandrel is allowed to stop so that the roll wound thereon can be removed.
During the winding operations on the several mandrels program cam 56 is advanced with respect to turret 12 in properly timed relationship to the progress of the wind by means of stepping motor 63 which is energized from switch 64 which is actuated by cam 66- rotating with bed 'roll 14.
Programmed fan drag clutch FIG. 11 illustrates another emobdiment of this invention in which modified means are employed to reduce the torque transmitting ability of a winding clutch in proportion to the square of the velocity of the mandrel. In this clutch, identified generally by the reference numeral 80, a number of components are employed which are the same as those employed in clutch 22 of FIG. 4 and like reference numerals will be used to identify common parts.
Clutch has a pulley 31 which is driven for rotation independently of mandrel 11 and which has a clutch face 34. Keyed to mandrel 11 for rotation therewith is an elongated sleeve 42. Sleeve 42 carries for rotation therewith a slidably mounted clutch ring 81 which has imbedded in one face thereof a circular array of friction pads 36 positioned to engage clutch face 34.
Friction pads 36 are urged against clutch face 34 by an array of compression springs 82 bearing on the back face of clutch ring 81 and carried in recesses in the face of a hub 83. Hub 83 is mounted for rotation with sleeve 42 but is movable axially thereon for the purpose of varying the compression of springs 82. Like the programmed Clutch 80 also has means which vary the torque im-' parting ability of the clutch in inverse proportion to the the same angular velocity as mandrel 11. Blades 84 rotating with mandrel 11 encounter resistance from the surrounding air of a magnitude which is directly proportional to the square of the velocity with which the fan is turned. This characteristic is inherent in fan means. The fan means is thus capable of absorbing torque in the same proportion as inertial torque is generated by deceleration of the rotating system and, in effect, prevents the clutch from transferring to mandrel 11 the equivalent of the inertial torque.
Operation of fan drag clutch 80 in conjunction with program cam 56 and the remainder of the winder is identical to the operation of centrifugal clutch 22 described above.
One of the principal advantages of varying the torque imparting ability of the winder clutch by speed responsive means such as the fan blades 84 of clutch 80 and the centrifugally actuated pad holders 37 of clutch 22 is that the clutch automatically compensates for different winding speeds. FIG. 12 illustrates by means of a family of curves the different torque profiles required to be imparted to the winding mandrelat different web speeds in order to wind a web at constant tension. The higher the Winding speed the less clutch torque must be imparted to the mandrel 11 in order to keep the tension in the wound web at the desired level. This requirement is the result of increased inertial torque effects present in the system at higher operating speeds. Both the centrifugal clutch 22 and the fan drag clutch 80 exhibit velocity squared characteristics closely corresponding to variations in inertial torque with changing winding speed. Both clutches, therefore, automatically compensate for changes in winder speed.
It will be noted from FIG. 12 that at winding speeds of 2,000 feet per minute and above a negative torque is actually required to be imparted to the winding mandrel at the beginning of the wind. It can be readily appreciated that the fan blades 84 of the fan drag clutch 80 can be designed to absorb more torque than is actually transferred to friction pads 36 and, in effect, apply negative torque to the winding mandrel at the beginning of the Wind. The fan drag clutch 80 is thus capable of operating throughout the speed range illustrated in FIG. 12. Centrifugal clutch 22 has the limitation of being unable to impart negative torque to the winding mandrel 11 and therefore cannot operate as effectively at speeds in excess of those at which the negative torque requirements at the beginning of the wind are in excess of that negative torque which is provided by the friction and windage of the system. For the examples illustrated in FIG. 12 this upper speed limit for the centrifugal clutch 22 is approximately 2,000 feet per minute.
From the foregoing it should be apparent that this invention provides novel means for improving the performance of high speed winding machines. The ability of clutch systems constructed in accordance with this invention to program clutch torque applied to winding mandrels and thereby maintain a uniform tension in the web being wound is of particular significance in winding weak webs, such as perforated toilet tissue, which may be caused to break by even slight variations in the Winding tensions.
Moreover, it should be apparent that this invention is useful in winding applications wherein a tension profile during the wind is desired which is something other than constant tension. For example, in winding high gloss films it is desirable to wind theinner layers of'the roll more tightly than the outer "layers in order to prevent slippage ofthe inner layers during the latter part of the wind. For such applications, it is' possible to alter the shape, or
profile, of the program segment 59 of-cam'-56 so as to impart to the clutch the'desired'torque transfer profile while'still essentially canceling the inertial torque by means of the speed responsive attributes of the system.
While the" invention has been described with reference to particular embodiments thereof it is understood that changes and modifications maybe made therein with out departing from the spirit and scope of the invention;
What is claimed'isi Y i 1. In web winding apparatus, a rotatable mandrel on which the'web'is to be wound, drive means, a clutch for'transmittin'g torque from said drive means to said mandrel, means responsive to the velocity of said mandrel and acting on'said clutch to reduce the torque transmitted to the mandrel as a'function of the square of the velocity of' the mandrel, and program means'responsive to the progress of a 'wind on said mandrel and acting on said clutch for progressively controlling the torque transmitting ability of the clutch over a range of values during the web wind.
2. In a web winding apparatus, a rotatable mandrel on which the web is to be wound, drive means, a clutch driven by said drive means and adapted to impart torque to said mandrel, means responsive to the velocity of said mandrel and acting on said clutch to reduce the torque imparted to the mandrel in proportion to the inertial torque in the winding apparatus, and program means responsive to the progress of a wind on said mandrel and acting on said clutch to progressively control the torque imparting ability of the clutch over a range of values during the web wind.
3. In web winding apparatus, a rotatable mandrel on which the web is to be wound, drive means, a clutch for transmitting torque from said drive means to said mandrel, said clutch being responsive to the velocity of said mandrel and exhibiting the characteristic of reducing the torque transmittable by the clutch with increasing man- ;0 93am 2 .IQAO qom o sq go Amrqe fiup rursuen enbro sq], onuoo iqoxrsselfioxd o1 qcnnp pres go sonspe oereqe sq], fiuyigrpour 1o; IQJPII'BUI pres uo purm 12 0 SSQJBOld on], o], olnsuodsel sueeur urexfiord pue A roopn exp values during the web wind.
4. In web winding apparatus, a rotatable mandrel on which the web is to be wound, drive means a clutch for transmitting torque from said drive means to said mandrel, said clutch including at least two friction members and means biasing said members into frictional engagement, centrifugal means responsive to the velocity of said mandrel for opposing said biasing means and enabling said clutch to exhibit the characteristic of reducing the torque transmittable by the clutch in proportion to the square of the mandrel velocity, and program means responsive to the progress of a web wind for progressively increasing the effectiveness of said biasing means to modify the characteristics of said clutch during a wind, said program means being effective to control the torque transmitting ability of the clutch over a range of values during the wind.
5. In web winding apparatus, a rotatable mandrel on which the web is to be wound, constant velocity drive means, a clutch for imparting torque to said mandrel when the clutch is driven by said drive means, fan means rotating with said mandrel and acting on said clutch to reduce the torque imparted to the mandrel in proportion to the square of the velocity of the mandrel, and program means responsive to the progress of a wind on said mandrel and acting on said clutch for progressively controlling the torque imparting ability of the clutch during the web wind.
6. In apparatus for winding webs at constant velocity and with a predetermined tension profile, a rotatable r 1 1 7 mandrel on which the web is wound, a turret supporting said mandrel and adapted to move the mandrel into winding position, constant speed drive means, clutch means carried by said mandrel and capable of imparting a varying torque to said mandrel when the cltuch is driven by said drive means, and said clutch means exhibiting the ability to impart a reduced torque in proportion to the square of the velocity of the mandrel, means tor adjusting the torque imparting ability of said clutch means, cam means', movatale with respect to said turret for actuating said adjusting means, and means responsive to the progress of a web wind for actuating said cam means 7. In web winding apparatus having a plurality of rotatably mounted mandrels, turret means supporting said mandrels and adapted to successively index said mandrels into winding position, drive means, means carried by each of said mandrels and adapted to be driven by said drive means when its mandrel is in winding position, clutch means carried by each of said mandrels capable of imparting varying torque to the mandrels from said driven means, and means for varying the torque im- 1.2 v i e i .v a parting ability of the clutch means during a web wind, said varying means being adapted to maintain the torque imparting ability of the clutch at a high level as the mandrel approaches winding position to insure rotation of the mandrel at a velocity comparable to the velocity of said drive means, to reduce the torque imparting ability of the clutch to a lower level as a web is transferred to the mandrel-for winding, and to subsequently progressively increase the torque imparting ability of the clutch during a web wind.
References Cited UNITED STATES PATENTS 2,694,300 11/1954 Cherigie 24275.5 X 2,741,102 4/1956 Monkley 242-55 X 2,769,600 11/1956 Kwiteck et al. 24264 X 2,796,222 6/1957 Frankel 242--75.5 2,901,192 8/1959 Nystrand 24275.5
GEORGE F. MAUTZ, Prima/y Examiner.