US1978073A

US1978073A - Tensioning mechanism for printing presses

Info

Publication number: US1978073A
Application number: US665304A
Authority: US
Inventors: Belcher Daniel
Original assignee: Bemis Brothers Bag Co
Current assignee: Bemis Brothers Bag Co
Priority date: 1933-04-10
Filing date: 1933-04-10
Publication date: 1934-10-23
Anticipated expiration: 1951-10-23

Description

Oct. 23, 1934. D. BELcHER TENS'IOHING MECHNISM FOR PRINTING PRESSES Fi1ea.Apri1 1o. lss

I A Sheets-Sheet l s' l: ATTORNEYS.

Oct. 23, 1934.

D. BELCHER 1,978,0734

TENSIONING MECHANISM FOR PRIIN'IIIGr PRESSES i u 4 S'hee' Filed April 10, 1933 s-Sheet 2 .DAN/EL .BEL c//Ee @www Trae/VEYJ TENSIONING 'MEGHANISM FOR PRINTING` PRESSES Fi1ed.Ap`ri1 1o, 195s 4 Sheets-Sheet 3 IAWENTORT EL 554 CHER l l I BY M A TTO YS.

Oct..23, 1934.

D. BELCHER TENSIONING MECHANISM'FOR PRINTING PRESSES Fi1ed.Aprii1 1o, 1953 4 sheets-met 4 e Q E w 5 NLMN L @E m T. if m? ,o w uw Fw -%4 mi,

,9 Z L. uws A o m-:cf Y W15. 5 7,u u 6 .om 7.. m mom M Patented Oct.l 23, 1934 iJNITED STATES 1,978,073 TENSIONING MEggNISM FOB PRINTING poration of Missouri Daniel Belcher, Minneapolis,

Bemis Bro. Bag Co., Minneapolis Minn., assignor to Minn., a cor- Applieaton April i0, 1933, Serial No. 665,304

13 Claims.'

This invention relates to an improved tensioning mechanism adapted for use in connection with. rotary printing presses, and is an improvement over the form shown in my patent, No. 1,653,199,

5 issued December 20, 1927.

In printing presses of the rotary type comprising a printing cylinder and an impression or blanket cylinder, between which cylinder the web is fed to receive an impression, dilcuity is somel times experienced in the handling of the web before and after passing between said cylinders in order to relieve it of unnecessary tensional strains, which may be imparted thereto, as a result of improper tensioning of the web. in order to vary the i spacing between impressions, the web is intermittently bed between the printing and impression cylinders, and the traveling speed of the web between said cylinders is relatively higher than the speed at which it travels when delivered to the machine and discharged therefrom. Because o! this differential in the traveling speed of the web, means must be provided for automatically taking up slack or tensioning the web portions between the feed rolls of the machine and the printing and impression cylinders, so that the web portions between said feed rolls and printing and impression cylinders will always be kept taut, regardless of the feeding of the new webinto the n achine and the feeding of the printed web therefrom. In printing presses of the character. above described, the web is intermittently fed between the printing and impression cylinders, and its movement may be/completely lnterrupted at times between impressions, even though the unprinted web is being constantly fed into the machine, and the printed web discharged therefrom at the same speed. It will thus beI understood that means must be provided for taking up the slack in the web between the points where it is fed into the machine and discharged therefrom, so as to maintain the webunder tension at all times.

The novel tensioning mechanism herein dis-A (Cl. lol-228) web of material, either paper or cloth, before such material is made into sacks or bags, ior various purposes, having means whereby the distance between the impressions may be varied to a predetermined degree, said distance depending upon G0 the size of the bag or sack to be manufactured from the web of material.

Objects of the invention reside in the specific construction of the means provided for tensioning the web portions entering and leaving the printing andjimpression cylinde in the means for relieviigthe web of severe tensional strains when the impression cylinder contacts with the printing cylinder to initially start the feeding action of the web between said cylinders; inthe speciiic construction and mounting of the tensionrollers whereby said rollers will oscillate about a 'common axis, and in opposite directions, so that as the imprinted new web is being fed into the machine, the slack therein will be taken up by one of said rollers, while the other of said rollers will be moving in the opposite direction to permit the printed web portion to discharge from the machine at the same speed as the imprinted web is being fed thereto; in the specific construction 80 ythe following description and accompanying drawings and will be pointed out in the annexed 95 claims.

In the accompanying drawings, there has been disclosed a structure designed to carry out the various objects of the invention, but it is to be understood that the invention is not conned to the exact features shown as various changes may be made within the scope of the claims which follow.

In the drawings: A -Flgure 1 isa longitudinal sectional view of a conventional printing press withsome of the parts omitted and showing the invention applied Figure 2 is anl enlarged detail view showing the tensioning mechanism in-normal position;

Figure 3 is a longitudinal sectional view showing the tensioning mechanism in operative posi' ion;

Figure 4 is a cross-sectional view on the line 4--4 of Figure 3;

Figure 5 is an enlarged detail sectional view on the line 5-5 of Figure 2; and

Figure 6 is an enlarged detail sectional View on the line 6--6 of Figure 2.

In the selected embodiment of the invention here shown, for purposes ofdisclosure, there is illustrated in Figure 1, a portion of a conventional printing press of the offset type, comprising the usual main frame 5 having an impression cylinder 6 suitably mounted thereon and the usual complementary printing rolls 7 which are adapted;Ax

to receive supplies of ink from suitable inking rollers, not shown. The impression cylinder 6 is shown provided with suitable printing surfaces or blankets 8 suitably secured to the periphery thereof, and which are adapted to peripherally engage a printing cylinder 9, shown mounted in suitabe bearings 11 supported in brackets 12 on the main frame 5.

At the opposite end of the machine, there is shown the usual feed roll 13, which cooperates with a relatively smaller feed roll 14 to feed the unprinted web 15 to the printing and impression cylinders 9 and 6, respectively, as will be under- `stood by reference to Figure 1. The unprinted web is supplied to the machine frame in a roll 16 supported upon a suitable spindle 17 mounted upon a frame extension 18. From the roll 16, the web passes around suitable idler rollers 19 and 21, as shown. The printed portion of the web is guided around the feed roll 13 by

suitable rollers

22 and 23, and over an idler 24 from whence it is wound into a roll 25 supported upon a suitable spindle 26 also mounted upon the frame extension 18. Suitable means, not shown, is provided for driving the spindle 26 to wind the web thereon.

v The novel means herein disclosed for 'automatically tensioning the web portions entering and leaving the printing and impression cylinders, is shown comprising a pair of

anti-friction rollers

27 and 28, preferably constructed of a relatively light weight-material such as aluminum. 'Ihe

rollers

27 and 28 are rotatably supported in a pair of arms 29 by suitable anti-friction bearings 31 mounted upon suitable studs 32 secured to the arms 29. The arms 29 have their intermediate portions secured together by a tubular connecting member 33 having flanged sleeve members 34 suitably secured to the ends thereof which, in turn, are secured to the arms 29 by bolts 30, as shown. Anti-friction bearings 35 support the tubular cross member 33 and arms 29, and are supported upon suitable pivot studs 36, secured by caps 41 to the upper rails 38 of the intermediate frame section 39. The arms 29 and cross member 33 are thus secured together for operation as a unit, and cooperate to provide a common support for the

rollers

27 and 28, which support will hereinafter be referred to ,by the numeral 37.

From the

feed rolls

13 and 14, the unprinted web passes downwardly under an idler- 42, then forwardly around another idler roller 43, and thence rearwardly around the lower roller 28 of the support 37, from whence it is guided between the impression and printing cylinders 6 and 9, respectively, by a suitable roller 44. This roller is shown provided with a brake device comprising a pair of fricton elements 45 and 46 pivoted to the main frame at 47, and having their opposite ends suitably connected together by an adjusting screw 48 and a wing nut 49. A compression spring 51 is coiled about the screw 48 between the element 46 and wing nut 49, to frictionally hold the brake elements in engagement with a cylindrical extension 52 provided at one end of the roller 43, whereby the rotation of said.roller may be retarded or entirely interrupted, if desired.

From the impression and printing cylinders, the printed web passes over a fixed guide 53, thence rearwardly over the upper roller 27 of the support 37, and forwardly around a relatively larger roller 54, having its periphery provided with suitable corrugations. From the roller 54, the web passes beneath the guide roller 22 and around n,the feed roll 13, as shown.

-able bolts 30, which secure said arm to the adjacent sleeve member 34, as shown in Figures 2 and'4. The opposite end of the spring is attached to the frame 39 whereby said spring normally holds the support 37 in the position shown in Figures l and 2, wherein the. lower portions of the arms 29 of the support are engaged with suitable stops 58, carried by arms 59 secured to a rock shaft 61 journaled in

suitable bearings

62 and 63, secured to the side Lframe members 39. The stops 58 are preferably provided with suitable yieldable elements 64 such as rubber, to cushion the impact of the arms 29 therewith.

The oscillatory movement of the arms 59 is limited in one direction by suitable stops 65, secured to the main frame and provided with suitable cushion elements 66. When the support 37 is in its normal position, as shown in Figures 1 and 2, the arms 59 will be engaged with the stops 65, as clearly illustrated in Figures 1 and 2.

'I'he movement of the arms 59 is limited in the opposite direction by a suitable stop 67 provided on one of the frame members 39 and adapted to be engaged by an adjusting screw 68 carried by an extension 69 on the hub of an arm 70.

A brake drum 71 is secured to one end of the shaft 6l and has a brake band 72 frictionally engaging the periphery thereof, one end of which is anchored to the bearing bracket 62 as indicated at 73. The opposite end of the brake band has a rod 74 secured thereto, which is received in a bracket 75 secured to one of the frame members 39. A suitable compression spring 76 is coiled about the rod 74 between the bracket 75 and a nut 77, received in threaded engagement with the end of the rod, as shown in Figures 2 and 4. 'I'he nut 77 and spring 76 provide means whereby the frictional engagement of the brake band with the drum may be varied, as desired. The brake band functions to retard the rocking movement of the shaft 61, as will subsequently be described.

Means is provided for moving the arms 59 from the positions shown in Figure 2 to that shown in Figure 3, and comprises a connecting rod 78 having one end pivotally connected to the arm 70 secured to the rock shaft 61, and having its opposite end slidably supported in a guide 81 in the lower end of a cam arm 82, the upper end of which is lpivotally supported upon the bracket 12 by a pivot 83. The rod 78 extends through the guide 81 and has a suitable compression spring 84 coiled thereabout, one end of which engages the guide 81 and its opposite end a washer 85 seated against a nut 86 which is adjustably mounted upon the threaded end portion 87 of the rod, whereby the tension in the spring 84 may be varied. A suitable roller 88 is mounted on the arm 82 andengages the periphery of a cam 89 having a high point 91y adapted to engage the roller 88 and move the arm 82 in a direction towards the right, when viewed as shown in Figures 2 and 3, to the position shown in Figure 3. When the cam arm 82 isthus actuated, the arms 59 on the rock shaft 61 will be moved forwardly in a direction towards the oscillating arms 29, until the adjusting screws 68 engage the stops 67, in which position they will be temporarily retained by the brake 71-72. The purpose of thus actuating the, arms 59 is to initially set into motion the support 37 for the

tension rollers

27 and 28 so that the roller 28 will temporarily release thetension in the loop 92 of the web to permit the feeding movement of the web to be started between the printing and .impression cylinders without imparting an excessive strain to the web.

In the operation of feeding the web between the printing and impression cylinders, it is to be understood that the web is fed between said cylinders only when the blanket 8 contacts with the web. The printing and impression cylinders rotate continuously and have the same peripheral speed, but no feeding action is imparted to the web when the blanket 8 is out of contact therewith, as shown in Figures 1 and 3, which results in the' web being fed between the cylinders intermittently. 4It is further to be understood that the web is'fed between the printing and impression cylinders at a relatively greater speed than the web is fed into and out of the machine by the feed rolls 13 and 14, which makes it necessary to provide means for compensating for the differential in speeds of the web travel. When the leading edge 60 of one of the blankets 8 engages the web, the latterA is fed between the printing ,and impression cylinders, whereby the loop 92 formed in the unprinted web portion will shorten, 'as shown in Figure 3, as aresult of the web being fed between the printing and impression cylinders at a greaterA speed than it is delivered to the machine, and such feeding action of the web will cause the support 37 to swing from its normal position, shown in Figure 2,`to a position such as shown in Figure 3 against the tension of the spring 55. Such action of -the support 37 will cause the loop 93 formed in the printed portion of the web to elongate as a result of the swinging action of the upper'tension roller 27, whereby the tension applied to the upper and lower portions of the web will compensate for the increased 'speed of the web as it is fed between the printing and impression cylinders.

As soon as the blanket moves out of feeding inders being temporarily interrupted. During such return movement of the arms 29, the trav' cling movement of the web portion 94 between the friction roller 44 andthe xed guide. 53 may be substantially interrupted.` When a blanket againvengages the web portion 94, the web will again berfed between the printing and impression cylinders to be printed upon. The `high point 91 of the cam is so timed with respect tothe leading edges 60 of the blankets, that the cam will engage the roller 88 of the arm 82 at substantially the same time that each blanket moves into feeding engagement with the web portion 94, to intermittently feed it between the printing and impression cylinders. Such engagement of the cam with the roller 88 will impart an initial thrust or movement to the arms 29 of the support 37, so that at the instant that one of the blankets engages and picks up the web and feeds it between the cylinders, the shortening of the loop 92 ofthe imprinted portion of the web will causethe arms 29 to continue to oscillate from their normal positions to that shown in Figure 3, or until the blanket moves out of contact with the web, whereupon the arms are immediately returned to their normal positions by the spring 55.

Stop means are provided on the intermediate frame section 39 for limiting the oscillation of the lower portion of the support 37 in a direc- Ption towards the printing and impression cylinders. Two such stop means are provided, one on each side of the machine, and as they are alike in construction, but one will be described in detail. Each stop means comprises a springactuated stop, generally indicated by the numeral 95, comprising a head 96 having a rod 97 slidably mounted in suitable guides 98 and 99 provided upon a member loladjustably mounted in a bracket 102 secured to the upper and lower rails of the side frame members 39. A collar 103 is secured to the rod 97 and is engaged with one end of a spring 104, the opposite end of which is seated against the guide 99, as best shown in Figure 3. The spring 104 constantly urges the stop 96 in a directionrtowards the support 37. A suitable resilient element 105 is seated in the".l head 96 to cushion the impact of the lower vportion 37 with said stops. The member 101 of the stop 95 has a stud 106 secured thereto, which is movable in 'an' arcuately formed 'slot 107 provided in the iis bracket 102. A suitable nut 108 is received in 'im 4to the bracket 102 in adjusted position.

A relatively longer stud 109 is also secured to the member 101 and, like the stud 106, traverses 1 the slot 107 in the bracket 102. A pinion 111 is shown rotatably mounted upon the stud-109. and has an operating handle 112 secured to the hub thereof by such means as a set screw 113. A suitable nut or collar 114 is received in threaded engagement with the outer end of the stud 109 to retain the pinion 111 thereon. The pinion meshes with a gear segment 115 secured to the bracket 102, whereby the stop member 101 may be relatively adjusted upon the bracket, when the nut 108 is loosened, to thereby relatively adjust the position of the stop member 101 upon said bracket.

'I'he position of the stop members 101 upon the brackets 102 are determined by the eective lengths of the transfer blankets secured to the periphery of the impression cylinder 6. In other words, if' the blankets are comparatively short. the stop members 101 may be positioned as shown in Figure 3, and when the blankets are relatively 1 longer, as when a larger impression is to be made uponrthe web, the stop members 101 may be moved upwardly in the arcuate slots 107, in a direction towards the printing cylinder 9, whereby-the oscillatory movement of the lowerportion 159- of the support 37 will be greater. The stops 95 are so adjusted that the lower portions of the arms 29 of the support 37 will engage the heads 96 of said stops each time a blanket moves out of contact with the printing cylinder 9. 1t will thus be seen that during the printing operation, when the web portions 94 is being fed between the printing and impression cylinders at a relatively higher speed than the web is being fed into the machine, the

rollers

27 and 28 will be oscillated about the axis of the support 37, the lower tension roller 28 moving in a direction towards the printing cylinder, and the upper tension roller 27 moving in the opposite direction. Because of the roller 27 moving in a direction away from the printing cylinder 9, during the printing operation, the slack which tends to form in the web portion constituting the loop 93 will be taken up by said tension roller. At the same time, the web portion forming the lower loop 92 will be kept taut by the action of the roller 28 at the lower portion of the support 37, as will readily be noted by reference to Figures 2 and 3.

Operation 1n the operation of this novel web tensioning mechanism, the unprinted web is threaded between the feed rolls 13 and 14, and around the

complemental guide rollers

42 and 43 in the usual manner, and it is then looped around the lower tension roller 28 of the support 37, and thence around the friction roller 44 and between the printing and impression cylindersas shown in Figure 3. The web is then passed over the fixed guide 53 and around the upper tension roller 27 of the support 37, thence around the rollers 54 and 22, and over the feed roll 13. When the web is initially threaded through the machine, the support 37 will be in the position shown in Figure 1, against the stops 58. It is to be noted that when the support 37 is in normal position, as shown in Figure l, the arms 59 supporting the stops 58 will be engaged'with the fixed limit stops 65, as shown in Figures 1 and 2. The movable stops 95 are then adjusted upon the brackets 102 according to the effective lengths of the transfer' blankets to be used, so that the lower ends of the arms 29 of the support 37 will engage the stops 96, when the tail end 116 of each blanket moves out of feeding contact with the web portion 94, as shown in Figure 3. The machine is then ready for operation, and each time a transferA blanket moves into feeding' contact with the web portion 94 engaged with the periphery of the printing cylinder 9, the arm 82 will be actuated by the cam 91 to initially set the support 37 into motion to advance the tension roller 28.in a direction towards theprinting cylinder 9, said initial starting of the support 37 being caused by the thrust exerted thereagainst by the stop 58, as a result of the rod 78 being actuated by the arm 82- and cam 91. As hereinbefor'e stated, the cam 91 is so timed with respect to the leading edges of the transfer blankets, that the arm 82 will be actuated just before each blanket movesv into feeding contact with web 94 so that the tension in the web portion forming the loop 92 will be temporarily released just before each transfer blanket engages the web to feed it between the printing and impression cylinders. The thrust imparted to the lower portions of the arms 29 of the support 37 by the forward movement' of the stops 58, is such that the web portion forming the loop 92 will tighten around the tension roller 28 before the forward momentum .imparted limiting means.

thereto is interrupted, whereby the relative shortening of the loop 92 will cause the lower portion of the support 37 to continue in a forward direction until the feeding action of the web between the printing and impression cylinders ceases. As soon as the transfer blanket moves out of feeding contact with the web portion 94, the support 37 will engage the stops 95, whereupon the support 37 will be returned to its normal position by the spring 55, as shown in Figure 1. Such return movement of the support 37 results because of the interruption of the traveling movement of the web portion 94 betweenthe cylinders 9 and 8 and further, because of the continuous feeding of the unprinted web into the machine.

The tensioning mechanism herein disclosed is comparatively simple in construction and is so designed that the web portion being fed through the machine is relieved of severe tensional strains, which might result in breakage of or damage to the web. The thrust imparted to the lower portions of the arms 29 of the supporting member 37 is important in that it starts the support 37 in motion immediately before the transfer blanket moves into feeding contact with the web portion 94, whereby said web portion may be readily started in motion without subjecting the web to severe tensional strains. The swinging action of the

tensioning rollers

27 and 28 automatically takes the slack in the web before and after printing:v so that the web is always maintained taut. By -relieving the web of excessive tensional strains at the beginning of each printing operation as herein set forth, the machine may be operated at a relatively higher speed than machines of a similar character now in common use, thereby greatly increasing the output of the machine tively adjusting the stops 95- of the tensioning mechanism, the machine-may be quickly adapted for making large or small impressions, and the spacing between impressions may also be varied, depending upon the sizes of the bags into which the web is to be manufactured.

I claim as my invention:

1. In combination with a printing press comprising web feeding rolls, and printing and impression cylinders adapted to print a web fed intermittently between them, of rolls for applying tension to the web before and after the printing operation, said rolls having a common springactuated support mounted for swinging movement between said feeding rolls and said printing and impression cylinders, and means for limiting swinging movement of the support in one direction, comprising a movable element which also' is operable to set said support into motion, each time the feeding operation of the web is initially started between saidprinting and impression cylinders, thereby to relieve the web of excessive tensional strains, said support being actuated entirely by the pullof the web thereon, after it has been initially set into motion by said 2. In combination with a printing press comprising web feeding rolls, and printing and imf able stop with which said support is normally engaged, and means operating in timed relation to said printing and impression cylinders for interturned thereagainst at the completion of each cycle of operation of said support.

3. In combination with a printing press comprising web feeding rolls, and printing and imi the web of excessive tensional strains at the bepression cylinders adapted to print a web fed intermittently therebetween, of means for applying tension to the web before and after passing between said printing and impression cylinders, said means comprising an oscillatable support having guides over which the web is fed, means for constantly urging the support in one direction, a

movable stop against which said support is normally engaged, and means operating in timed relation to the rotation of said printing and impression cylinders for intermittently actuating said stop, whereby it will thrust said support forwardly each time said cylinders move into feeding engagement with the web, thereby to`relieve ginning of each printing operation.

4. In combination with a printing press comprising web feeding rolls, and printing and impression cylinders adapted to print a web fed therebetween, of means for applying tension to the web portions entering and leaving said printing and impression cylinders, said means comprising guides over which the web is fed, an oscillatable `support common to said guides, means for constantly urging said support in one direction, and a movable stop against which said support is normally engaged, said movable stop' comprising a pivoted arm having a friction device associated therewith lfor preventing *reboundingk of said pivoted-arm, when the stop thereof is suddenly impinged by said support upon return of the latter` to its normal position.

5. In combination with a printing prem comprising' web feeding rolls, and printing and impression cylinders adapted to print a web fed therebetween, of means for taking up slack in the web before .and after passing'between said4 cylinders, saidmeans comprising a movable support `having rollers over which the web is fed, a

movable stop, a spring operatively connected with said support and constantly urging it into engagement with said stop, and means for operating said stop to cause thelatter to start said support-in motion at about the same instant that the printing and impression cylinders move into feeding engagement with the web, thereby to relieve the web of excessive tensional strains, when the feeding operation of the webl is initially started between said' cylinders, said support being operated by the pull of the web'thereon, after having been initially started by said stop.

6. In combination with a printing press comprising web feeding rolls, and printing and impression cylinders adapted to print a web fed therebetween, of means for simultaneously taking up slack in the web portions entering and leaving said cylinders, said means comprising a :nov-

is initially started between said printing and impression cylinders, said last mentioned means comprising a cam-operated arm having an operative and yieldable connection lwith said stop and operating in Atimed relation to the operation of the printing and impression cylinders.

7. In combination with a printing press comprising printing and impression cylinders adapted to print a web fed therebetween, of means for taking up slack in the web before and after passing between said cylinders, said means comprising rollers overv which the web is fed, a support common to said rollers mounted for swinging movement about an axis disposed between said rollers, a movable stop, means constantly urging the support into engagement with said stop, and means associated with the printing cylinder for suddenly thrusting said stop forwardly, at the beginning of each feeding movement of the web between the printing and impression cylinders, whereby said support is initially set into motion to thereby relieve the web 'of excessive tensional strains, each time the feeding operation of the web is initially started between said cylinders.

8. In combination with a printing press comprising web feeding rolls, and a constantly rotating printing cylinder with which the web is peripherally engaged, and an impression cylinder having a blanket secured to the periphery thereof and adapted to Contact with the web and intermittently feed it between said printing and impression cylinders, of means for applying tension to the web before and after passing between said cylinders, said means comprising a support mounted for swinging movement and having guides engaging the web, a movable vstop for said lmeans for exerting a sudden forward thrust againstV said stop, whereby the latter will initially set said support into motion just before the blanket moves into feeding engagement with the web, to thereby relieve the web of excessive tensional strains, each time it is initially started, said stop being rendered inoperative to further actuate said support, during completion of each feeding movement ofthe web between said printing and impression cylinders. t l

9. In combination with a printing press comprising web feeding rolls, and a constantly rotating printing cylinder with which the web is peripherally'engaged, and an impression cylinder having a blanket secured to the periphery thereof and adapted to contact with the web and intermittently feed it between said printing and impression cylinders, of means for applying tension to the web prior to and following the printing operation, said means comprising a movable support having guides engaging the web, a movable stop for limiting movement of said support in one direction, yieldable means constantly urging said support into engagement with said stop,

and means associated with the printing and impression cylinders for setting said support into motion before the blanket moves into feeding engagement with the web, whereby the web is relieved of excessive tensional strains at the beginning of each feeding movement between said cylinders, said support thereafter being actuated entirely by the pull of the web thereon.

10. In combination with a printing press comprising webfeeding rolls, andI printing and impression cylinders between which the web is intermittently fed to be printed upon, a support mounted for swinging movement and having a tension roller thereon engaging the web, a stop movable within predetermined limits and with which said support is normally engaged, yieldable means constantly urging the support into engagement with said stop, a cam-actuated arm having an operative connection with said stop and adapted to actuate the latter just before the feeding operation of the web between the printing and impression cylinders is started, whereby said stop will thrust said support forwardly at substantially the same instant that said cylinders engage the web to feed it therebetween, whereby the web is relieved of excessive tensional strains each time the feeding operation thereof is initially'started as a result of said cylinders moving into feeding engagement therewith, said support' thereafter being operated entirely by the pull of the web thereon.

11. In combination with a printing press comprising web feeding rolls, and printing and impression cylinders between which the web is intermittently fed to be printed upon, rollers for applying tension to different runs of the web, a swingable support for said tension rollers, stops for limiting the swinging movement of said support, one of said stops being adjustable to vary the movement of the support, and the other of said stops being movable Within predetermined limits, means constantly urging the support into engagement with said movable stop, a friction device associated with said movable stop for retarding its movement, and a cam-device associated with said printing and impression cylinders and having an operative connection with said movable stop and adapted to operate it in a direction to set said swingable support into motion, just before the blanket on the impression cylinder moves into feeding engagement with the web, whereby the latter is relieved of excessive tensional strains each time it is fed between the printing and impression cylinders.

12. In combination with a. printing press comprising web feeding rolls and printing and impression cylinders adapted to print a web fed therebetween, of means'for applying tension to the web portions entering and leaving said printing and impression cylinders, said means comprising guides over which the Web is fed, an oscillatable support-common to said guides, means for constantly urging said support in one direction, a movable stop against which said support is normally engaged between printing operations, a cam-actuated arm associated with the printing cylinder, means operatively connecting said arm with said movable stop and adapted to thrust said stop forwardly each time the printing and impression cylinders move into feeding engagement with the web, whereby said support is initially set into motion by said stop to thereby relieve the web of excessive tensional strains, each time said cylinders move into printing and feeding engagemen't therewith, the movement of said support thereafter being completed by the pull of the web thereon, and a friction device for retarding the return movement of said movable stop.

13. In combination with a printing press comprisingweb feeding rolls and printing and impression cylinders adapted to print a web fed therebetween, of means for applying tension to the web portions entering and leaving said printing and impression cylinders, said means comprising guides over which the web is fed, an oscillatable support common to said guides, means for constantly urging said support in one direction, a movable stop against which said support is normally engaged between printing operations, a cam-actuated arm operating in timed relation to the printing cylinder and having an operative connection with said movable stop, said camactuated arm operating said stop to cause the latter to intermittently thrust said support forwardly at substantially the same instant that the printing and impression cylinders move into feeding engagement with the web, whereby said support is initially set into motion by said stop to thereby relieve the web of excessive tensional strains, each time said cylinders move into printing and feeding engagement therewith, and a friction device for retarding the return movement of said movable stop, when it is subsequently engaged by said support.

DANIEL BELCHER.