US2990989A - Compensator for web sheet - Google Patents

Description

y 1961 H. R. CARLSEN 2,990,989

COMPENSATOR FOR WEB SHEET Filed Jan. 26, 1959 2 Sheets-Sheet 1 INVENTOR HARRY ECARLSEN 5%M C %7 ATTORNEY J 1961 H. R. CARLSEN 2,990,989

COMPENSATOR FOR WEB SHEET Filed Jan. 26, 1959 2 Sheets-Sheet 2 INVENTOR HARRY IQ.CARL5EN ATTORNEY 2,990,989 COMPENSATOR FOR WEB SHEET Harry R. Carlsen, Northfield, Minn., assignor to G. T. Schjeldahl Company, Northfield, Minn., a corporation of Minnesota Filed Jan. 26, 1959, Ser. No. 789,017 8 Claims. (Cl. 22635) This invention relates to mechanism for evenly feeding webs from roll material, and more particularly to a cornpensator adjustable to multiple webs which are fed in side-by-side arrangement, but at independent rates of feed.

In machines requiring the rapid feeding of web material, the linear speed demand may be varied or may be intermittent in nature. Thus, where a web must be advanced and then stopped, as for cutting, printing or other steps necessitating a momentary'quiescent state of the web, inertia of the rolled web material may cause trouble. Thus, the capacity of the machine may be limited or the web may be erratically tensioned and stressed. Since a roll of web material such as thermoplastic sheeting may be quite heavy, it is not practical to start and stop the rotary motion thereof as the material is unrolled. In order to keep the roll unwinding in a more or less steady manner while the webmaterial is intermittently advanced for processing, a rocker-type compensator has been developed for taking up slack and exerting tension on the web to keep the roll turning even when the portion of the web beyond the compensator is momentarily quiescent. Where the nature of the web material is such as to not properly withstand tensioning, as it is pulled from the compensator, it has been proposed to insert a positive drive roll which will pull and unwind the web from the roll at a speed proportional to the amount of tension exerted on the Web beyond the compensator as reflected by the degree to which the compensator rocks against its counteractant resilient force. The more the compensator roll tends to rock against resilient force, the greater will the proportional drive be to compensate for the increased demand for unwinding the web material. A variable speed drive has been used for this purpose, and the adjustment for the drive can be made through a simple linkage between the compensator rocker arms and the control lever of the variable speed drive.

It has been found, however, that much of the time simple tensioning of the web is adequate to unwind the web and positive driving is unnecessary and may even cause trouble by over compensating. If a roll of web material is almost depleted, the tension required for unrolling is comparatively less and may need no auxiliary help whatsoever. On the other hand, if a sudden surge is needed for speeding up operation or to overcome the inertia of a large supply roll, then the auxiliary help must be adequate and instantaneous. Prior art compensators have generally failed to meet the extreme demands of fragile web roll material during the unwinding process.

The problems mentioned above are further complicated where it is desired to steadily feed, through the same mechanism, a plurality of webs similarly advanced in intermittent motion at different rates of speed and from different supply rolls of web material.

It is within the contemplation of this invention and a general object thereof to overcome the above noted difficulties and to provide a feed compensator which will be rapid in response, yet capable of meeting extreme demands in feeding web material for intermittent proc-' essing from stock rolls.

More specifically, it is an object of the invention to provide a web and feed compensator which has means for rates atent Patented July 4, 1961 driving of web material from roll stock.

Another object of the invention is to provide a machine of the class described which is capable of compensating web travel and tensioning on a plurality of webs which are simultaneously fed therethrough but requiring but one variable drive to accomplish the multiple compensa tion.

These and other objects and advantages of the invention will more fully appear from the following descrip tion, made in connection with the accompanying draw ings wherein like reference characters refer to the same parts throughout the several views and in which:

FIGURE 1 is a side elevation of the compensator mechanism, unessential portions being cut away and hidden parts shown in dotted outline;

FIGURE 2 is an end elevational view of the compensator mechanism taken from the right of FIGURE 1, the webs being removed from the mechanism for clarity; and

interdependence of the compensator parts.

With continued reference to the drawings, the web feed compensator utilizes a web supply structure which may be in the form of an upright support 10 secured to base 11 and provided with a horizontal shaft 12, upon which are rotatably mounted in side-by-side relation a pair of web supply rolls 13 and 14, as shown. Details of the roll supply are not shown and it is understood that the web material 15 and 16 which is fed from the respective rolls 13 and 14 may be folded, printed or otherwise handled without disturbing the continuity of the webs prior to their entering the compensator, at which point the webs lie in horizontal side-by-side alignment. The handling of the web material is such as to allow for different rates of web travel and for different weights of rolls 13 and 14, as well as different diameters of the respective rolls.

The compensator mechanism itself is shown generall at 17 and has a supporting frame 18 mounted on a base 19 such as to properly align the webs 15 and 16 as they enter the compensator and as they leave it.

Mounted on base 19 is a variable speed drive 20 which may constitute a source of power such as a motor 21 and variable speed output 22, as shown in FIG. 2. The variable speed output 22 has an output shaft 23, the speed of rotation of which is governed by the position of lever 24. Lever 24, in turn, is pivotally connected to link 25, to crank arm 26 secured rigidly to the control shaft 27 which, in turn, extends across the entire supporting frame 18 and is journalled in bearings 28 secured in alignment at each side of the frame 18. A pair of radial pins 29 and 30 are secured adjacent the respective ends of the shaft 27 and lie in the same plane therewith. The purpose and function of the radial pins 29 and 30 will be described later in this specification.

Shaft 23 which extends from the variable speed drive 22 connects directly with the capstan or drive roll 31 over which both of the webs 15 and 16 pass, as shown in FIG. 1. Thus, irrespective of the speed demands of the separate webs, the drive roll 31, being unitary, will rotate throughout its length at whatever speed is prescribed by the outlet shaft 23 of the variable speed drive 22. The

a shaft 33. A pair of sleeves 34 are mounted upon the shaft 33 and each has an inward radial arm 35 terminating in close proximity and independently movable with respect to the other. At the outer ends of the respective sleeves 34 are provided crank levers 36 which have downwardly terminating radial arms 37 lying in alignment with the respective arms 35. Journalled across each of the respective pairs of radial arms 37 for each of the sleeves 34 is a pinch roll 38, the rolls 38 lying in parallel relation with the capstan or drive roll 31. Webs 15 and 16 pass over the common drive roll 31 but underlie their respective pinch rolls 38 so that, whenever the crank arm 36 is raised, the associated pinch roll 38 will be caused to move downwardly into contact with its associated web 15 or 16 and cause the same to be pinched against the rotating capstan or drive roll 31. The pinching effect, of course, causes the web to be forced against the drive roll and thereby to advance at whatever speed the drive roll is rotating. As the webs 15 and 16 pass over the drive roll 31, they pass through the respective identical rocker frames 39 which are mounted for rotation upon the common shaft 40, in turn secured across the frame uprights 18, as shown. Each frame 39 comprises a pair of spaced parallel rocker arms 41 and a pair of spaced parallel rollers 42 and 43 journall ed for free rotation across the respective ends 44 and 45 of the arms 41. A pair of shafts 46 and 47 are secured across the frame 18 in spaced horizontal relation, the shaft 47 lying above the shaft 46, as shown in FIG. 1. On shaft 46 in side-byside relation are mounted for free rotation a pair of rollers 48. Similarly, on shaft 47 in side-by-side relation are mounted a pair of rollers 49.

As a web is fed over the capstan or drive roll 31, it then passes under roller 42 of the rocker frame 39, then passes upwardly over a roll 48, then back under the roll 43 which is mounted at the other end of the rocker frame 39. The web then passes forwardly over the roll 49 and thence to a mechanism, not shown, which may further act upon the webs. It will be noted that, as the rocker frame pivots in a clockwise direction around shaft 40 as shown in FIG. 1, slack will be taken up in the web and it may continue to be fed into the compensator even when the same web has been stopped in its travel forwardly of the compensator. Conversely, as the rocker frame 39 pivots counterclockwise, slack in each web will be lessened and the rocker frame will yield accordingly. Under such circumstances, the web may be momentarily removed from the compensator at a greater rate of travel than that of the same web as it passes over the drive roll 31. It is understood, of course, that, if the increase or decrease in demand for web output is more than just momentary, then the rate of unwinding of the roll must be adjusted accordingly. Pinch rolls 38 are normally relaxed and lie in spaced clearance with the drive roll 31. Thus, unless the crank arm 36 is raised, the drive roll 31 will rotate without imparting any driving force to the web. A resilient connection indicated generally at 50 is pivotally secured to the crank arm 36 and also to the rocker frame at the upper end 45 of rocker frames 39. The resilient connection includes a tension spring 51 and a length adjustment 52, as shown in FIG. 1. When there is a maximum of slackin the web, upper arm portion 45 of the rocker frame 39 will be at its lowest position. Resilient connection 50 will then exert zero tension upon the crank arm 36 and the pinch roll 38 will relax and permit the web to pass freely thereunder without being driven by the drive roll 31. The instant the pulling demand on the web increases so as to tend to remove the slack, then the rocker frame 39 will begin to pivot in a counterclockwise direction. Spring 51 will come under tension and the pinch roll 38 will instantaneously cause the pinch roll 38 to bring the web into driven engagement with the capstan or drive roll 31. The web will then be caused to enter the compensator at whatever speed is imparted thereto by the drive roll 31. If greater demand is placed upon the web as it leaves the compensator, the rocker frame 39 will continue to pivot in a counterclockwise direction. However, since the pinch roll '38 is already 4 in contact with the drive roll 31, the spring 51 will merely stretch while maintaining the pinch roll 38 in contact with the web and drive roll 31.

Also responsive to the pivoting of the rocker arms are a pair of actuators 53 connected respectively to the rocker frames 39 at a position above the shaft 40. The actuators 53 each have a link 54 pivoted at 55 to the upper arm portion 45 of rocker frame 39 and extending downwardly to a pivot connection 56 with the radius arm 57. Each of the radial arms '57 are mounted for free rotation at their other ends to the shaft 27 adjacent the respective radial ends 29 and 30. The radial arms 57 are provided with laterally extending abutment members 58 which are adapted to contact the respective radial pins 29 and 30 whenever the associated arm 57 is caused to rotate in a counterclockwise direction. It will be remembered that rotating the shaft 27 and its fixed crank 26 in a counterclockwise direction as shown in FIG. 1, will result in actuating the variable speed lever 24 so as to increase the rate of rotation of the output shaft 23. Since the construction of each of the rocker frames 39 and its associated actuator 53 is identical in construction and since the radial pins 29 and 30 on shaft 27 lie in a common plane, the shaft 27 will rotate in a counterclockwise direction as viewed in FIG. 1, in response to the rocker frame 39, whose abutment 58 will first contact the associated radial pin. As soon as the shaft 27 begins to rotate as noted above, the lever 24 will move in a clockwise direction and the shaft 23 will begin to speed up, imparting faster driving rotation to roll 31. Since any movement of the rocker frame 39 which will speed up the variable speed drive also maintains the pinch roll 38 in contact with drive roll 31, the increase in speed will drive web at a faster rate into the compensator. If the pull on a web leaving the compensator becomes still greater, the rocker frame 39 will continue to turn in a counterclockwise direction, thus causing the variable speed output shaft 23 to rotate at a still greater rate of speed. If equilibrium is established between the rate of feed and the rate of departure of a web, then the rocker frame 39 will remain at a stabilized inclination. Now, however, if the travel demand on the web is decreased, then the rocker frame 39 will pivot in a clockwise direction with its associated actuator 53 permitting shaft 27 to turn in a clockwise direction, thereby slowing down the speed of shaft 23 and the capstan or drive roll 31.

Where a plurality of webs are being fed simultaneously over the drive roll 42, it must be remembered that, even though one of the actuators 53 relaxes with respect to the shaft 27, the other one may not. Under such circumstances, the rocker frame 39 which is pivoted to the greatest degree in a counterclockwise direction will control the operation of the variable speed drive. In other words, the drive roll 31 will always respond to the greatest demand between a plurality of webs fed simultaneously thereover. If the disparity between the web demands continues, then the rocker frame 39 of the slower moving web will begin to move clockwise as the slack in the web increases. The drive roll 31 will continue to operate at a speed according to the demand of the other rocker frame and, hence, the web fed to the rocker frame under consideration will be in excess of the speed required. The rocker frame will thus continue to relax until the associated pinch roll 38 will move away from the drive roll 31. At this point, the demand of the web will transmit tension directly to the incoming web and its associated roll and will continue to be fed from the roll until the drag imparted by the roll will exceed the tension on the web as it travels from the compensator. When the demand again increases, the associated rocker frame 39 will again cause the pinch roll 38 to establish a driving connection between roll 31 and its web. The foregoing compensation has been accomplished for a plurality of webs with but a single drive roll and a single variable speed drive therefor.

It will, of course, be understood that various changes may be made in the form, details, arrangements and proportions of the parts without departing from the scope of the invention as set forth in the appended claims.

What is claimed is:

1. In a web feed compensator a mechanism having rolls in engagement with a web and adapted to shift so as to increase and decrease the distance of web travel through the compensator, a drive roll positioned adjacent said web prior to its entering said mechanism, a pinch roll shiftable towards and away from said drive roll and into and out of pressing engagement with the web and drive roll so as to impart driving motion from the drive roll to the web and then to interrupt said driving motion, said pinch roll normally being out of engagement with said web and said drive roll, and a resilient link interconnecting the pinch roll and the mechanism, said link shifting the pinch roll with increasing force to drive the web when the mechanism shifts to decrease the distance of web travel and said link with decreasing force shifting the pinch roll out of engagement with the drive roll to interrupt driving of the web when the mechanism shifts a predetermined amount to increase the distance of web travel.

2. In a web feed compensator a mechanism having parallel rolls in engagement with the web and pivotally mounted for rocking in one direction to increase the distance of Web travel and in the other direction to decrease the distance of web travel through the compensator, a drive roll positioned adjacent said web prior to its entering said mechanism, a pinch roll pivotally mounted in parallel relation with said drive roll and adapted to swing into and out of pressing engagement with the web and drive roll for imparting driving motion from the drive roll to the web and then to interrupt said driving motion, said pinch roll normally being out of engagement with said web and said drive roll, and a resilient link interconnecting the pinch roll and the mechanism whereby said mechanism, when rocking to decrease the distance of web travel through the compensator, will cause said pinch roll to impart driving motion from the drive roll to the web.

3. In a web feed compensator, mechanism adapted to shift resiliently to take up and give up slack in a web as it is fed under variable tension, a drive roll positioned adjacent the web prior to its entering said mechanism, variable speed means adapted to rotate the drive roll, an actuator interconnecting the mechanism and the variable speed means for increasing the rate of rotation of the drive roll as the mechanism shifts to give up slack, a pinch roll confronting the drive roll with said web disposed therebetween, and means resiliently interconnecting the pinch roll and said mechanism, said pinch roll moved from said drive roll by said resilient means when said mechanism shifts a predetermined amount in taking up web slack.

4. In a web feed compensator for a pair of webs, a pair of mechanisms for the respective webs adapted each to shift resiliently to take up and give up slack in a web as it is fed under variable tension, a drive roll in close parallel relation adjacent both of said webs prior to their entering said respective mechanisms, a variable speed means adapted to rotate the drive roll, a pair of actuators respectively interconnecting said mechanisms and the variable speed means for increasing the rate of rotation of the drive roll in response to the mechanism which shifts I web slack,

5. A compensator mechanism for feeding rolled web material which comprises, a rocker frame mounted pivotally intermediate its ends on an axis parallel to the plane of the web when fed thereto, a roller at one end of the rocker frame journaled for rotation on an axis parallel to the pivot axis of the rocker frame and adapted to rotatably contact one surface of a web, a roller at the other end of the rocker frame journalled for rotation on an axis parallel to the pivot axis and adapted to rotatably contact the other surface of the web, a variable speed drive means having a roll adjacent said web prior to passing over said rocker frame, a link interconnecting said rocker frame and the variable speed drive mechanism and adapted to increase the speed of the variable speed drive r011 when the rocker frame tends to rock in a direction tending to permit the web to travel in a straight line, a rotatable pinch roll mounted on an axis confronting that of the variable speed drive roll with the web interposed therebetween and shiftable into and out of pinching engagement therewith, a resilient link between said rocker frame and the pinch roll whereby said rocker frame, upon movement under web tension, will first cause pinching of the web against the variable speed drive roll and, upon continued increasing tension, will cause compensative increase in the driving speed of the drive roll.

6. A web feed compensator as set forth in claim 3 wherein said actuator comprises a mechanical linkage interconnecting said mechanism and said variable speed means.

7. A web feed compensator a set forth in claim 3 wherein said means resiliently interconnecting said pinch roll and said mechanism comprises a tension spring.

8. In a web feed compensator, mechanism adapted to shift resiliently to take up and give up slack in a web as it is fed under variable tension, a drive roll positioned adjacent the web prior to its entering said mechanism, variable speed means adapted to rotate the drive roll, an actuator interconnecting the mechanism and the variable speed means for increasing the rate of rotation of the drive roll as the mechanism shifts to give up slack, a pinch roll confronting the drive roll with said Web disposed therebetween, and means resiliently interconnecting the pinch roll and said mechanism, said pinch roll diverging from said drive roll to permit slippage of the web thereover when the mechanism shifts to a predetermined degree in taking up slack and said pinch roll converging on said drive roll in pressing contact to cause driving force to be imparted upon said web when said mechanism is rotated to a predetermined position in response to increasing web travel.

References Cited in the file of this patent UNITED STATES PATENTS 989,871 Pringle Apr. 18, 1911 1,115,828 Johnston Nov. 3, 1914 1,916,467 Eger July 4, 1933 2,800,326 Berger July 23, 1957 2,807,465 Newell Sept. 24, 1957

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