US2205867A

US2205867A - Web replenishing means

Info

Publication number: US2205867A
Application number: US176848A
Authority: US
Inventors: Walter C Scott
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-11-27
Filing date: 1937-11-27
Publication date: 1940-06-25
Anticipated expiration: 1957-06-25

Description

June 25, 1940. w. c. sco'rT 2,205,867

WEB REPLENISHING MEANS Filed Nev. 27, 1937 5 Sheets-Sheet 1 I INVENTOR m ATTORNEY June 25, 1940. w, c, sco -2,205,867

WEB REPLENI SHING MEANS Filed Nov. 27, 1937 5 Sheets-Sheet 2 ATTORNEY W. c. SCOTT 2,205,867

WEB REBLENISHING MEANS Filed Nov. 27, 1937 I 15 Sheets-Sheet 5 INVENTOR Mile] (3 Jmlf ATTORNEY June 25, 1940. w. c. SCOTT 2,205,867

WEB REPLENISHING MEANS Filed Nov. 27, 1957 5 Sheets-Sheet 4 INVENTOR fiager f Jmi/ v ATTORNEY W. C. SCOTT WEB REPLENISHING MEANS 5 Sheets-Sheet 5 Filed Nov. 27, 1937 H mw w a l xv m mw mm \L v Q 4 N Qw I Q a n w INVENTOR Jim 6 Jaw/f BY W ATTORNEY Patented June 25, 1940 UNITED STATES PATENT OFFICE 18' Claims.

This invention relates generally to web replenishing or web splicing mechanism in which a rotatable replenishing web roll is provided with a pasted portion and has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web. More specifically it relates to the class of devices in which a shield is rotated at the same speed as the roll and serves to protect the pasted portion thereof while the roll is brought up to the desired speed, said shield being thereafter rel-eased from its driving means and retarded to thereby expose said pasted portion, the paster being made while the roll continues its rotation.

The problem of releasing the shield from its driving connection and stopping it is a serious one and I have found that brakes for retarding the shield will not operate satisfactorily because the speed attained by the shield at the moment of its release will vary and therefore the brakes will be called upon to meet different operating conditions with the result that the retardatio of the shield becomes non-uniform.

The main object and feature of this invention 25 is to make the speed of deceleration of the shield proportional to the speed of rotation of the web rolL-the higher the speed of the roll the greater the speed of deceleration of the shield and the slower the speed of the roll the less the speed of deceleration of the shield, the device thus being self-compensating, as it were.

The invention can best be understood in connection with the accompanying drawings in which the invention is clothed in several forms, 35 and in which:

Fig. l is a view in side elevation with partsbroken away and in section of a web supply mechanism embodying one form of the inven-' tion;

Fig. 2 is a sectional View substantially on the plane of line 2-2 of Fig. 1, with parts shown in elevation;

Fig. 3 is an enlarged sectional view of the left-hand end of Fig. 2, but showing the parts at a different moment in the cycle of operations;

Fig. 4 is a diagrammatic view showing relation of the elements of a variable transmission means employed in connection with my invention; and

Figs. 5 and 6 disclose a modified form of invention, Fig. 5 being somewhat diagrammatic and showing the mechanism associated with one of the three rolls usually employed, and Fig. 6 being a sectional view substantially on the plane of line 66 of Fig. 5.

A conventional form of roll stand I0 is disclosed in Figs. 1 and 2, said roll stand having a rotatable shaft II to which spiders i2 are keyed at opposite ends thereof. Each of the spiders here consists of a hub portion 13 and three arms 5 it, each set of opposed arms carrying a web roll designated here for convenience as active roll I5, replenishing roll l6 and reserve roll ll. l8 indicates the running web leading from theactive roll to a web-pulling machine such as a printing machine into which the running web is threaded.

i9 indicates a pasted portion on the leading end of the web of the replenishing roll, and such pasted portion can be a part of the web itself or may consist of tabs applied thereto, and it may be continuous lengthwise of the roll or interrupted in accordance with different standard practices employed in the art. 20 is a shield, arranged in the instant form of the invention to extend throughout the length of the web roll, said shield being preferably supported closely adjacent to but out of contact with the surface of the web roll, so as not to mar the surface of the roll, by means of. shield arms 2|. The width of the web to be supplied will vary with the requirements of the printing machine and can, for instance, be two, three or four pages wide depending upon the character of the product desired; and the shield, if it is to cover the entire 30 field of the pasted portion of the web, is therefore made adjustable and this is here. accomplished by having two slidably related overlapping or telescoping

members

22 and 23 so that, when spiders i2 are adjusted on shaft ii to sup- 35 I port the desired width of web, the length of the shield will be automatically adjusted. So likewise, the diameter of web rolls vary and, in order to support the shield in proper relation to the surface thereof, shield arms 2| are composed of two

members

24 and 25 that are slidably related by slots 26 and bolts 21 so that the shield can be supported at a greater or lesser distance radially from the center of rotation of the roll. As will be seen from Fig. l, the contour of the shield 5 circumierentially of the roll is preferably arcshape with taper ends 28 so as to avoid a too abrupt transition of the accelerating means, in this form of the invention running web I8, from the surface of the roll to the shield and vice 50 versa.

The means that support web roll 16 may take the form of a continuous core shaft or, as here shown, two

core members

29 and 3|] are employed. Core member 29. has a short spindle 3| 5 of oscillation of crank 42.

rotatably mounted in spider arm I l and shield arm 2| is loosely mounted on said spindle 3|; core member 35 has a somewhat longer spindle or shaft 32 mounted in the spider arm it opposite to that which supports spindle 3!, and the other shield arm 2! is loosely mounted on said shaft 32.

Suitable means are provided to move the shield in unison with core shaft 32, to release it therefrom and to thereafter retard said shield by driving it at a gradually decelerating speed to bring it substantially to a stop. In the present instance these means take the following form: keyed to vcore shaft 32 is a clutch member 33 having openings 34 for the reception of pins 35 carried by sliclable clutch member 36, whichlatter is loosely mounted on shaft 32. Hub 3'! of shield arm 2! is loose on core-shaft 32 but is provided with openings 33'with which pins 35 are always in engagement so that whatever rotative movement is imparted to clutch member 36 will betransmitted to shield arm 2!. It will now be understood that, when clutch member 36 is moved to the right (in Fig. 3), pins 35 will engage openings'ini of clutch member 33 and that these instrumentalities constitute connectable and disconnectable means to drive the shield from coreshaft 32 and in unison therewith. Carried loose- :ly on 'core-shaft'32 is a transmission member 39 and keyed to shaft 22 is a slidable clutch membe r M! the purpose of which is to couple or uncouple member 39 to and from shaft 32. Member 39 carries a crank M and, when said mem- ;ber is coupled to shaft 32, crank M will make one revolution to each rotation of shaft 32;

42 in dicates asecond crank secured to rockshaft 43 carried by spider arm M, and M is a connecting rod pivotally connected to cranks ll and as. as is a controller in the form of a gear, hav- 'ing a rising and falling speed, loosely mounted on shaft 32 and oscillated by suitable transmission be manipulated, and 53 is a lever pivoted at 55 for moving clutch member into and out of engagement with 39. is an actuating lever pivoted at 56 and designed to be moved by cam fill on clutch 36 to cause pin 55a to engage and lift upper end of lever 53 to uncouple clutch 40 from 39. The short end of lever 55, carrying pin f 55a, is normally urged downward either by being made heavier than the long end or by the action of a spring 551).

Before proceeding to describe the operation of the device, it will be well to study the interrelation of the two cranks 4| and i2 and the manner in which they are articulated, that is, their relative length, their position circumferentially with respect to each other and the length of connecting rod M that extends between them. Reference will now be had to Fig. 4 in which A indicates the center of rotation of shaft or member ,32 and therefore also the center of rotation of crank ii; it also designates the-center of oscillation of controller 45. B indicates the center When transmission member 38 is clutched or coupled to shaft 32, crank ll makes one revolution to each revolution of said shaft and of the web roll supported by it. Crank 4| is relatively short as compared with the length of crank 42, crank 52 being in the present instance twice as long as 4|. The

result is that a complete rotation of crank M will not cause a complete rotation of crank 42 but will oscillate the latter, which oscillating movement is in turn transmitted to controller i5. But also, the oscillating movement of crank 62, and therefore of controller 25, will not be uniform as to speed but will be rising and falling going from zero to high speed and then back to Zero. The full lines of il, 2 and M in Fig. 4 indicate the high speed position of crank 42. Now it will be evident that deceleration of the shield should be accomplished in less than one revolution of "shaft 32 because, after the shield has passed the point of contact with running web E5 or other accelerating device, and it is desired to effect the paster, the shield should not again come in contact with said running web or other accelerating device. Also it will be apparent that the transfer of the control of the shield from shaft 32 to controller should be effected at a time when said controller is moving at substantially the same speed as the shield and that necessarily requires that crank d2 shall at that moment be moving at its highest speed, and that sufficient time must be allowed in which to bring said crank 42 up to full speed. For the purpose of making this clear, let us trace the movement of crank (62 during its movement in one direction only.

The dot and dash position of M, 42 and i indicates the position of the parts at zero or at the beginning of the movement of crank 22 in one direction. As will be observed, the parts are so articulated that, at that moment, connecting rod i l lies parallel to crank M and overlies the lat--v ter. Movement of crank il from point-'0, in the direction indicated by the arrow will now gradually accelerate the movement of crank 32 until point I) is reached. During this time crank d2 has moved from point x to point y and is new traveling at its highest speed. Continued movement of crank iii from point I) now imparts a decelerating movement to crank d2 until point e is reached. When crank' li reaches point 0, crank 22 'is at point 2 which is the zero point at which no motion or very little motion takes place. The position of the parts at this moment is indicated by the dotted lines, and it will be observed that connecting rod d4 now forms a straight-line extension of crank l Continued rotation of crank ii will now reverse the movement of crank 32 and will cause it to move in the other direction until crank it again reaches point a. During its movement from point a to point e, crank (H has traveled somewhat more than one hundred eighty degrees, that is, slightly more than one-- half of a revolution of shaft 32, and crank 32 in traveling from a: to a has moved somewhat more than forty-five degrees. However, the period during which the shield has been decelerated is represented by the travel of crank M from b to c which in this instance is somewhat less than ninety degrees of revolution of shaft 32. It is not intended by the foregoing to convey the impression that the relative length and circumferential positionof the two cranks and the length of the connecting rod herein disclosed must necessarily be used, but the relationship shown has been found convenient and effective for the purpose indicated. To sum up the matter: the train of elements from is to Q5 constitutes a timed driv-' ing means in which is included a variable speed mechanism, here the two connected cranks, for gradually retarding or decelerating the shield after it is released from member 32.

The operation of the device is as follows: before starting acceleration of the wab roll, clutch 36 is moved to the right in Fig. 3 thereby bringing pins 35 into openings 34 thus connecting the shield to shaft 32. This movement also serves to move cam 57 away from actuating lever 55 and as the short end of 55 is heavier than the long end or is moved by a spring 55b it drops away from lever 53 thereby permitting clutch it to engage member 39 thereby coupling said member to shaft 32. Themovement of clutch l-t can be effected by hand or springs (not shown) can be utilized to effect this movement automatically when 53 is released by 55. The web roll is now accelerated either by running web l8 or other means, and the shield being connected to shaft 32 will move in unison with the roll and protect the pasted portion thereof. Rotation of shaft 32 will also rotate crank 45 in unison with the roll and crank d2 will oscillate thereby oscillating controller 45 which latter is mounted loosely on shaft 32.. When the roll has attained uniting speed, clutch 36 is moved to the left when recess t9 and tooth are opposite to each other, thereby releasing the shield from shaft 32 and connecting it to controller 45. This happens at the moment when controller s5 is traveling at its highest speed, that is: when crank 42 is at the point y in Fig. .4, and the transfer of the control of the shield from 32 to 45 is therefore elfected without shock. The speed of crank ill now begins to decelerate and when it is substantially at zero, point a, Fig. 4, cam 5'! will have moved to a position where it will contact lever 55 and. cause the latter to throw out clutch 45 thereby preventing continued rotation of crank ll and consequently preventing continued movement of controller 45. It is not necessary that this action take place absolutely at zero; it may occur slightly before or slightly after crank A 2 reaches this point so that when clutch it! is thrown out the parts may still have a slight movement which however is soon brought to an end by the inertia of the parts. The important point is that the speed of deceleration is always proportional to the speed of the web roll, and that the shield is controlled at all times. As the web roll continues its rotation the paster will be effected in a manner well understood in the art.

In Figs. 5 and 6 is shown a modification in which gears =35, t5 and s? are replaced by two oscillating cranks 58 and 59 here of equal length, and a connecting rod 69, crank 58 becoming the equivalent of controller 45. Cranks ti and 42 are shown in the zero position as are cranks 58 and During the time that crank t! travels approximately one hundred eighty degrees from the position shown, cranks 42, 53 and 59 travel in this instance approximately ninety degrees from zero to the other zero position indicated in dash dot lines. The middle of the stroke or high speed position of cranks d2, 58 and 59 is indicated in dotted lines. It is not intended to convey that the relative length and circumferential position of the cranks shown need be followed, it is merely one instance of an effective arrangement that may be used. The operation of this modified form is in all essentials the same as that de scribed in connection with the form shown in Figs. 1 to 4 inclusive.

I claim:

. 1. In a web replenishing mechanism in which a. rotatable web roll isprovided with a pasted portion and has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web, a member driven in unison with the web roll; a rotatable shield connected to said member to travel in unison therewith and to protect the pasted portion of the web roll during acceleration of the speed of rotation of said roll; means to release said rotatable shield from said member; driving means timed to move in unison with said member; and connections, including variable speed mechanism, from said driving means and connectable to said shield unison with the webroll; a rotatable shield con-;

nected to said member to travel in unison therewith and to protect the pasted portion of the web roll during acceleration of the speed of rotation of said roll; means to release said rotatable shield from to move in unison with said member; and connections, including a pair of cranks, from said driving means and connectable to said shield to retard the shield, after said shield has been released from celerating speed that is proportional to the speed at which said member moves.

. In aweb replenishing machanism in which a rotatable web roll is provided with a pasted portion has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web, a member driven in unison with the web roll; a rotatable shield con-- nected to said member to travel in unison therewith and to protect the pasted portion of the web .roll during acceleration of the speed of rotation of said roll; means to release said rotatable shield from said member; driving means timed to move in unison with said member; and connections,

including two connected cranks one rotatable andthe other oscillatory, from said driving means and connectable to said shield to retard the shield, after said shield has been released from said member, at a gradually decelerating speed that is proportional to the speed at which said memb er moves.

4. In a web replenishing mechanism in which a rotatable web roll is provided with a pasted portion and has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web, a member driven in unison with the web roll; a rotatable shield connected to said member to travel in unison therevith and to protect the pasted portion of the web roll during acceleration of the speed of rotation of said roll; means to release said rotatable shield from said member; driving means timed to move in unison with said member; and connections, including two connected cranks one relatively short and rotatable and the other relatively long and oscillatory, from said driving means and connectable to said shield to retard the shield, after said shield has been released from said member, at a gradually decelerating speed that is proportional to the speed at which said member moves.

5. In a web replenishing mechanism in which a rotatable web roll is provided with a pasted por tion and has its speed of rotation accelerated to uniting speed before it is united by its pasted said member; driving means, timed,

said member, at a gradually de-.

portion to a running web, a member driven in unison with the web roll; a rotatable shield to cover the pasted portion of the web roll during acceleration of the speed of rotation of said roll; connectable and disconnectable driving means to drive the shield in unison with said member during acceleration of the speed of rotation of said web roll; driving means connectable and disconnectableto and from said member; and connections, including a variable-speed transmission mechanism, from said driving means and connectable to said shield to retard said shield, after said shield has been released from said member, during less than one revolution of the web roll, at a gradually decelerating speed to thereby bring the shield substantially to a state of rest and to expose the pasted portion of the web roll while said roll continues its rotation.

6. In a web replenishing mechanism in which a rotatable web roll is provided with a pasted portion and has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web, a member driven in unison with the web roll; a rotatable shield, driven from and in unison with said member, to cover the pasted portion of the web roll during acceleration of the speed of rotation of said roll; a controller having a rising and falling speed; means to release said shield from said member and to connect it to said controller substantially at the moment when the speed of said controller is equal to the speed of the shield; connections, including a variable-speed mechanism, driven by said member and driving the controller; and a device to disconnect said connections from said member substantially at the moment when the speed of the controller is at zero.

'7. In a web replenishing mechanism in which a rotatable web rollis provided with a pasted portion and has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web, a rotatable support for the web roll, driven by rotation of the web roll; a shield loosely mounted on said support to cover the pasted portion of the web roll during acceleration of the speed of rotation oi said web roll; connecting means to drive the shield from and in unison with the rotatable support; a controller having a rising and falling speed; connecting means to drive the shield from and in unison with the controller; a rotatable transmission element mounted on the rotatable support; a device to connect or disconnect the transmission element with respect to the rotatable support; a variable-speed transmission mechanism from said rotatable transmission element to said controller; and means to automatically actuate said device to disconnect the transmission element from the rotatable support a predetermined period after the shield has been connected to the controller.

8. In a web replenishing mechanism in which a rotatable web roll is provided with a pasted portion and has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web, a member driven in unison with the web, roll; a. rotatable shield, driven from and in unison with said member, to cover the pasted portion of the web roll during acceleration oi the speed of rotation of said roll; an oscillatory controller having a rising and falling speed; means to release said shield from said member and to connect it to said controller substantially at the moment when the speed of said controller is equal to the speed of the shield; connections, including a variable-speed mechanism, driven by said member and oscillating the controller; and a device to disconnect said connections from said member substantially at the moment when the speed of zero.

9. In a web replenishing mechanism in which a rotatable web roll is provided with a pasted portion and has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web, a rotatable support for the web roll, driven by rotation. of the web roll; a shield loosely mounted on said support to cover the pasted portion of the web roll during acceleration of the speed of rotation of said 15 web roll; connecting means to drive the shield from and in unison with the rotatable support; an oscillatory controllerha-ving a rising and falling speed; connecting means to drive the shield from and in unison with the controller; a rotatable transmission element mounted on the rotatable support; a device to connect or disconnect the transmission element with respect to the rotatable support; a variable-speed transmission mechanism from said rotatable transmission element to said controller to oscillate the latter; and means to automatically actuate said device todisconnect the transmission element from the rotatable support a predetermined period after the shield has been connected to the controller.

10. In a web replenshing mechanism in which a rotatable web roll is provided with a pasted portion and has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web, a member driven in unison with the web roll; a rotatable shield to cover the pasted portion of the web roll during acceleration of the speed of rotation of said roll; connectable and disconnectable driving means to drive the shield in unison with said member dur ing acceleration of the speed of rotation of said web roll; driving means connectable and disccnnectable to and from said member; and connections, from said driving means and connectable to said shield, including a pair of cranks so 45 articulated as to retard said shield, during less than one revolution of the web roll, at a gradually decelerating speed to thereby bring the shield substantially to a state of rest and to expose the pasted portion or" the roll while said roll con- .5

tinues its rotation.

11. In a web replenishing mechanism in which a rotatable Web roll is provided with a pasted portion and has its speed of rotation accelerated.

to uniting speed before it is united by its pasted portion to a running web, a member driven in unison with the web roll; a rotatable shield, driven from and in unison with said member, to cover the pasted portion of the web roll during acceleration of the speed of rotation of said roll; 6

a controller having a rising and falling speed; means to release said shield from said member and to connect it to said controller substantially at the moment when the speed of said controller is equal to the speed of the shield; connections e including a pair of cranks, driven by said member and driving the controller; and a device to disconnect said connections from said member substantially at the moment when the speed of the controller is at zero.

12. In a web replenishing mechanism in which a rotatable Web roll is provided with a pasted portion and has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web, a rotatable support 1 the controller is at 5 for the Web roll, driven by rotation of the web roll; a shield loosely mounted on said support to cover the pasted portion of the web roll during acceleration of the speed of rotation of said Web roll; connecting means to drive the shield from and in unison with the rotatable support; a controller having a rising and falling speed; connecting means to drive the shield from and in unison with the controller; a rotatable transmission element mounted on the rotatable support; a device to connect or disconnect the transmission element with respect to the rotatable support; connections including a variable-speed transmission mechanism consisting in part of a pair of cranks extending from said rotatable transmission element to said controller; and means to automatically actuate said device to disconnect the transmission element from the rotatable support a predetermined period after the shield has been connected to the controller.

13. In a web replenshing mechanism in which a rotatable web roll is provided with a pasted portion and has its speed of rotation, accelerated to uniting speed before it is united by its pasted portion to a running web, a member driven in unison with the web roll; a rotatable shield, driven from and in unison with said member, to cover the pasted portion of the web roll during acceleration of the speed of rotation of said roll; an oscillatory controller having a rising and falling speed; means to release said shield from said member and to connect it to said controller substantially at the moment when the speed of said controller is equal to the speed of the shield; connections, including a paid of cranks, driven by said member and oscillating the controller; and a device to disconnect said connections from said member substantially at the moment when the speed of the controller is at Zero.

14. In a web replenishing mechanism in which a rotatable web roll is provided with a pasted portion and has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web, a rotatable support for the web roll, driven by rotation of the web roll; a shield loosely mounted on said support to cover the pasted portion of the web roll during acceleration of the speed of rotation of said web roll; connecting means to drive the shield from and in unison with the rotatable support; an oscillatory controller having a rising and falling speed; connecting means to drive the shield from and in unison with the controller; a rotatable transmission element mounted on the rotatable support; a device to connect or disconnect the transmission element with respect to the rotatable support; connections including a variable-speed transmission mechanism consisting in part of a pair of' cranks extending from said rotatable transmission element to said controller to oscillate the latter; and means to automatically actuate said device to disconnect the transmission element from the rotatable support a predetermined period after the shield has been connected to the controller.

15. In a web replenishing mechanism in which a rotatable web roll is provided with a pasted portion and has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web, a member driven in unison with the web roll; a rotatable shield to cover the pasted portion of the web roll during acceleration of the speed of rotation of said roll; connectable and disconnectable driving means to drive the shield in unison with said member during acceleration of the speed of rotation of said web roll; driving means connectable and disconnectable to and from said member; and connections, from said driving means and connectable to said shield, including two connected cranks one rotatable and the other oscillatory, to retard said shield, during less than one revolution of the web roll, at a gradually decelerating speed to thereby bring the shield-substantially to a state of rest and to expose the pasted portion of the roll while said roll continues its rotation.

16. In a web replenishing mechanism in which a rotatable web roll is provided with a pasted portion and has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web, a member driven in unison with the web roll; a rotatable shield to cover the pasted portion of the web roll during acceleration of the speed of rotation of said roll; connectable and disconnectable driving means to drive the shield in unison with said member during acceleration of the speed of rotation of said web roll; driving means connectable and disconnectable to and from said member; and connections, from driving means and connectable to said shield, including two connected cranks one relatively short and rotatable and the other relatively long and oscillatory, to retard said shield, during less than one revolution of the web roll, at a gradually decelerating speed to thereby bring the shield substantially to a state of rest and to expose the pasted portion of the roll while said roll continues its rotation.

17. In a web replenishing mechanism in which a rotatable web roll is provided with a pasted portion and has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web, a member driven in unison with the web roll; a rotatable shield to protect the pasted portion of the web roll during acceleration of the speed of rotation of said roll; carrying means connected to said member to travel in unison therewith and to sustain said shield out of contact with the surface of the roll; means to release said carrying means from said member; and means to decelerate the carrying means after it is released from said member.

18. In a web replenishing mechanism in which a rotatable web roll is provided with a pasted portion and has its speed of rotation accelerated to uniting speed before it is united by its pasted portion to a running web, a member driven in unison with the web roll; a rotatable shield, to protect the pasted portion of the web roll during acceleration of the speed of rotation of said roll, composed of slidably related members to increase or decrease its length to accommodate it to different widths of web rolls; carrying means connected to said member to travel in unison therewith to sustain said slidably related shield members out of contact with the surface of the roll; means to release said carrying means from said member; and means to decelerate the carrying means after it is released from said member.

WALTER C. SCOTT.