US2743880A - Tension control system for printing press - Google Patents

Description

May l, 1956 H. l.. MOwHoRTER TENsIoN coNTRoL SYSTEM FOR PRINTING PRESS 2 Sheets-Sheet l Filed Aug. 14, 1952 H. L. MCwHoRTER 2,743,880

TENSION CONTROL SYSTEM FOR PRINTING PRESS Filed Aug. 14, 1952 2 Sheets-Sheet 2 May 1, 1956 United States Patent() l was@ TENSION CONTROL SYSTEM FOR PRINTING PRESS Henry McWhorter, Hinsdale, Ill., assigner to The Goss Pix'lllltrng Press Company, Chicago, Ill., a corporation o mois Applicationaugusf .14, 1952, serial No. 304,405 1 claim. l(ci. vzt'zL-vs) second element, which usually comprises some form of .braking means, is related to the rst in that it is responsive to the operation of the first element to maintainn a par- :ticular predetermined web tension .or to produce an increase or decrease thereof. 'Thus it is apparentV that the elfectiveness of the entire system is largely dependent on the sensitivity and responsiveness of the lirst element.

Numerous devices have previously been used to perform the function of sensing web4 tension changes. Examples of such devices include spring biased rollers, shock absorber mounted rollers, the so-called inertia-weight biased rollers or combinations thereof. However, none yof these devices has proved to be entirely satisfactory primarily because of their variable sensitivity and sluggish responsiveness. This has necessitated resort to complex auxiliary equipment for achieving adequate tension control. As a result, kprior tension control systems have been cumbersome, liable to malfunction, and not susceptible of economical manufacture.

Accordingly, it isthe general object of the invention to overcome the disadvantages of the prior tension control systems through the provision of a novel tension control system of an exceedingly simple characterv comprising relatively few components as compared to prior art .devices, thus minimizing initial cost and maintenance expense, and which .is highly sensitive to changes in/web tension and quickly responsive to correctthe same. v

The object of the invention thus generally set forth, together with other and ancillaryadvantages, are attained by the construction and arrangement shown by way of illustration in the accompanying drawings, in which:

Figure l is a fragmentary side'elevation of an auto matic paper reel assembly for supplying paper toa webfed printing press and including a tension control system embodying the features of the present invention.

Fig. 2 is a diagrammatic k representation of the tension control system shown in Fig. 1.

Fig. 3 is a diagrammatic representation of a press speed controller showing an auxiliary contact mechanism associated therewith. .Y Y A i n Referring more particularly to Fig. 1 of the drawings, there shown is an automatic paper reel assembly for a web-fed printing press. It includes a pair of spaced upright supporting frames of generally Y-shape upon which is supported a paper reel generally designated 11. The reel 11 is of the/type comprising a pair of spaced, three-arm spiders 12 for the support ofA spindles 13 upon which are rotatably mounted rolls of `paper 14`. vThe reel 11 includes a`central`sh'aft 15 onl whichit is""adapv'te'd,y to be rotated by means of a motor 16 and a suitalfole'gear'v 2,743,880 Patented May l, 19,56

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train, generally designated 17, enclosed within a housing l18 to index the paper rolls 14 supported thereby between loading, reserve, and operative feeding stations.

Mounted on thesupporting structure is a pre-drive assembly indicated generally at 20for bringing the reserve paper roll up to press speed 4prior to making a paster to supply the web from it to the press upon expiration of the paper roll in the operativeufeeding station. The predrive assembly includes belts 21 running about spaced Apulleys 22 and 23 and is adapted to be moved into engagement with the peripheral surface of the reserveV roll by meansof arpneumatic actuator 24. Ther belts 21 are `adapted to be driven by means of an endless beltbetween Athe pulley 23 and a dilerential mechanism indicated generally at 26, the latter being driven from they main press drive shaft (not shown). v v

Indicated also in Fig. 1 of the drawing, in phantom outline, is a paster assembly operative to effect the Yjoining of the running web W with the leading end of the paper on the reserve paper roll as the running web roll isl about to expire. The paster assembly 30, per se, forms no part of the present invention. For the details thereof, reference is made to applicants copencling application Serial No. 239,542,`i`1led July 3l, 1951, now United States Patent No. 2,689,095. Suiiic'e it to say for present vpurposes that lthe paster assembly 30) includes a carriage 31 4journaled on a'shaft k3:2 for swinging movement toward and away from the reel assembly by means of pneumatic piston and cylinder, actuator 33. A set of web deflecting brushes 34, are rockably supported on the carriage 31 for movement into and out of web engaging position by means of a pneumatic actuatorl 35. The web deilecting brushes 34are adapted to press the running web into engagement'with the new roll of paper so as toeiect a paster uponrindexing theV new roll from the reserve station upony expiration of ,the paperroll occupying the operative feedstation. After the paster rhas been made, the old web must be severed, and forthis purpose the paster assembly 3 0 is equippedwith a tail cutter 36.

In carrying out the present invention a floating roller 40 engaging in a loop'intherunning web W and suspended lfor lateral movement finto and out of the loop, with the movement thereof severely limited, is utilized asa Yweh tension sensing device. The limitation of movement, as will be seen, enables the-inertia eect of the floating roller to be substantially eliminated. The roller serves I W is fed from the paper roll 14 occupying the operative feeding station and lis passed4 about a cooking roller 48 whichis adjustably supported in position forappropriate movement to remove diagonal stress lines from the running web.` From thecocking roller, the web has .a U- shaped loop formed therein in the bight of which is disposed the oating roller 40. From the oating roller the lweb passes about a guide or lead-in roller- 49 'and then VupwardlyV tothe printing press (not shown).

vThe belt actuator-42comprises a hydraulicpiston ,S0

l l and cylinder 51 to eifect a pull on the tension belt 4 4. To

thisl end the actuator includes a pair of pulleys 52 and 53, respectively iixed to the supporting structure 10 and to the piston 50 and about which the belt 44 is looped. While in the drawings only one belt is shown for illustra- I`and passes'abou'tia guidroller 54 disposed betweenthe arrangement causes the belt to frictionally engage the periphery of the running web roll and thus apply a braking force thereto. Movement of the piston within the cylinder so as to extend or retract the tension pulley 53 determines the amount of braking force applied by the belt to the periphery of the running` web roll. p

It will be apparent that the piston 50'divides the cylinder 1'into two chambers 'Slafand 51b, which, for'convenience, will be referred to a`s`the tension-increase and tension-decrease chambers, respectively. Thus upon ,supplying pressure fluid to the tension-increase chamber the piston is extendedfthereby moving the tension pulley 5.3, outwardly (to the right) to effectively tightenthe belt i fandA increase frictional ,engagement thereof with the periphery of the running web'roll. l Movement of the ten- 'sion pulley inwardly results in a decrease of the braking force.

The supply of pressure fluid to' the belt actuator 42, as 'previously noted, is under the'control of pressure Huid regulating means, designated generally at 46. In the illustr'ative embodiment of the present invention, this rmeans f includes a jet pipe 55 enclosed within housing 56 and 'pivoted at 57 for lateral movement lbetween tension-increase and tension-decrease positions.

Pressuretluid is supplied to the jet pipe by way of a line 58 from a pump 59 which in turn draws its supply from a sump 60. Supply line pressure is under the control of a suitable pressure regulating relief valve 61 which is interposed between the supply line 58 and a drain line 62. The relief valve may be equipped with a suitable line pressure indicator 63.

`Pressure fluid supplied to the regulator`46 is directed through the jet pipe element 55 thereof and is directed toward two outlet orices 65,66. The latter are respectively connected to the tension-increase' and tension-decrease chambers of the cylinder 51 by way of lines 67 and 68. The two outlet orifices 65 and 66 are disposed in the path of lateral movement of the jet pipe 46 andare disposed in closely spaced relation to each other. It will be apparent that uponV movement of the jet pipe intoits tension-increase position, pressure uid Vtherefrom'will be supplied through outlet orifice 65 by way of the line' 67 to the tension-increase chamber 51a of the actuator cylinder 51. This results in an outward movement of the piston and consequently of the tension pulley 53. Such movement effectively shortens the tension belt 44 and thus increases the braking force applied' thereby to the running web roll 14. An increase in brakingforce obviously results in an increase in running webtension. Fluid contained in the tension-decrease chamber 51b of the actuator cylinder 51 is forced outwardly therefrom by way of the line 68 upon the aforesaid piston movement. Some of this uid finds its way back intor the regulator housing 56 from which it is returned to the sump 60 by way of the return line 62. Y

If there is an increase in running webtension above the normal setting, it is necessary to reduce the braking force applied by the belt 44 to the paper roll 14 Vto compensate therefor. Upon movement of the jet pipe of the regulator 46 into its tension-decrease position, pressure lluid output therefrom is discharged into the outlet orice 66 which, as previously noted, is connected to the tensiondecrease chamber 51b of the actuator cylinder 51 by way of the line 68.

In the practice of thepresent invention, however, line 68 is connected so that the uid is largely diverted to the return or drain line 62 with only minor pressure being applied to the decrease chamber of the actuator 51. Cornmunication with the return line is here effected by provid- `ing an interconnecting line 69 between the lines 62 and 68, the line 69 having a restriction therein indicated at 69a. Thus the major part of the pressure tiuid supplied from the regulator 46 is returned to the sump 60 and only a relatively small portion finds its way into the tensiondecrease chamber 51b of the cylinder 51 of the belt actuator 42. This small pressure tuid supply is suficient to retract the actuator pistony50, but with a force substantially less than that by which the piston is extended upon supply of pressure uid to Athe tension-increase chamber 51a.

As previously noted, movement of the jet pipe 55 of the hydraulic regulator 46 is under the control of the floating roller 40, with the jet pipe and the floating roller constrained to correspondingrnovement. Referring more specifically to the oating roller 4l), it is suspended from the supporting structure 10 for limited lateral movement into and outsof'the web'loop formed between the rollers 48 and 49. For this purpose, the floating rolleris journaled adjacent the lower ends of a pair of spaced arms 70 which'are'rigidwith a shaft 71. The latter, in turn, is journaled onthe supportingstructure 10. Intermediate its ends, one ofthe arms-70 is equipped with a push rod -72 having a at 72a thereon adapted for engagement with -a push pin 73` carried by the jet pipe regulator 46. The pushtpin 73 is received in a boss 74 formed integral withthe` regulator housing 56 and extends therethrough into the housing where it is'connected to the jet pipe 55. The regulator 46 is equipped' with a light compression-type spring 75 which' is interposed between the jet pipe 55 and the-interior of-'the housing 56 opposite the connection between the jet pipe and the push pin 73 to cause the jet pipe andthe push pin to follow the 'movement of the floating roller supporting arm'70.

Means is provided for maintaining the lioating rubber 40 in between the limits of its movement when the -wcb is running at the desired normal tension. Aln such position, the floating roller supporting arm I70, and the iet pipe`55, too,'will occupy their intermediate positions. A change 'in running web tension from the normal results in a corresponding dellection of the tioating roller et) and thus of the roller supporting arms 70, the push pins 72 and 73,'and `the jetl pipe 55 so as to immediately compensate for web tension change. In the present instance, the means Vprovided for maintaining the floating roller position comprises a' hydraulic actuator 78 of the piston and cylinder-type, theY piston of which acts directly on ythe oating roller supporting arm 79. Since there isa portion of the running webW acting to pull the floating roller 40 both on the top and on the bottom thereof, then the actuator 78 must exert a force equal to approximately twice the desired normal web tension. This can be readily achieved through appropriate choice of piston and cylinder size taking into consideration hydraulic'uid pressure with which it is 'supplied from the same source as'is the jet pipe regulator by way of pressure fluid supply lines 79 and 80. Since it'is necessary only to hold the oating roller in position against the action of the running web W, pressure iluid needbe supplied only to one side of the'piston of the actuator `78. Thus the holding force i exerted by the 'actuator"which, as noted above, amounts to about twice the desired normal web tension,-permits Y of control by means of a suitable pressure regulating valve 81 inserted in the supplyline 79. By means of this valve, the press operator can readily alter the setting of the normal web tension to' be' maintained, as might be 4necessary forA the proper operation of the printing press. Thus, adjacent the valve S1 and in the line 79, a suitable gauge or indicator 82, calibrated'directly in pounds of tension pull for the running web, is provided. t Adrain line 83 for the pressure regulating valve 81 is provided so that when the desired tension-'setting of the valve is reduced, excess tluidlcan bleed -back therethrough to the return line 62.

. satisfactory to effect proper tension control.

'Upon a 'decrease in running web tension, a compara-y `tivelylarge volume of ypressure iuid is =at once required toquickly move the oating roller. I For this purpose, a hydro-pneumatic accumulator 85 is connected into the floating roller actuator supply line 79. To accommodate the required volume of oil the supply line 80 between the accumulator 85 and the actuator 78 is made substantially larger than the supply line 79 between the pressure regulating valve 81 and the accumulator..

As previously noted, the outlet orices 65 and 66 of the jet pipe regulator 46 are comparatively close together tothe end thatfrelatively little lateral :movement is required of the jet vpipe between its tension-increase and `tension-decrease positions. Thus there need be relatively little-movement of the loating roller suspending'arms l70 to effect such jet pipe movement. By the same token, ytheresneed be but a very small lateral movement of the floating roller 40. It becomes apparent, therefore, that if suchmovement of the floating roller is severely limited, the inertia of the iioating roller is substantially eliminated as afactor to be considered in the determination of its responsiveness to changes in web tension. With the above described lconstruction and arrangement and the floating roller suspended for late ral swinging movement on a radius of approximately one foot (measured ybetween the center of the roller arm supporting shaft 71 and the axis of the floating roller) an actual lateral movement of the latter axis of only one-tenth of an inch has been found Since such a small amount of movement produces satisfactory rcsults and in order that floating roller inertia be eliminated as a factor, it is 'desirable that the permissible movement of the roller be limited substantially to that amount, for example, to one-fourth of kan inch. For this purpose, suitable stop means is provided which, inthe present instance, includes an outward movement-limiting stop 87 rigid with the printing press supporting structure. VAn inward ,moviement limiting stop 88, in the illustrative embodiment, is disposed within the cylinder of the floating roller actuator and is effective to limit inward movement of the actuator piston therein. 5 fllt can be shown that the running web tension should never be permitted to reach zero because if it does there will be a loss of control of the runningweb. .lf the press operator would never so operate vthe pressure regulating valve S1 (which controls theiluid pressure to vtheiioating roller actuator 73) to cutoif the pressure fluid supply thereto, then a certain amount of tension would always be maintained in the running web. VBut dependence on the 'operator only would be subjectto the` sofcalled hum`an factor. Therefore, to insure that there will be at least a minimum tension in thev yrunning webat all times even though there might be complete lossot` lud pressure in the floating roller actuator-78, means is'provided to exert a slight outward force on the' piston of the actuator with a corresponding outwardv force on the floating roller 40. In the present instance this is accomplished through the provision of a light expansion-type spring 89 which isl interposed between the vrear end of the actuator cylinder andthe face of its piston.

Press speed is normally reduced in steps by means yof the main press drive motor controller. Upon each step down in press speed there will be a correspondingmomem tary decrease in running web tension. In order to maintain control of running web tension by vmeans of the tension belt `44 under such conditions with the tension control system set to maintain but minimum tension in the web, and in accordance with one ofthe more detailed aspects of the invention, an auxiliary shifting device is provided to effect momentary movement of the jet pipe toward its tension-increase position so as to supply pressure fluid therefrom directly into the regulator outlet orifice 65 and thence by way of the line 67 to the pressure increase chamber 51a of the belt actuator cylinder 51.' As shown, this auxiliary device comprises a push-type solenoid 90 whichis 'mounted so l:thatits armtureegages" the oating roller supporting arm 70; It is operative to move the same outwardly to effect a corresponding movement of the jet pipe regulator push pin 73 and of the jet pipe 55. As shownY in Fig. 3,r the solenoid 90 is actuated through the provisionof suitable contacts 91 on the press drive motor controller indicated generally at 92. The contacts 91 are closed as the motor controller arm is moved in the decrease direction by means of a rack and pinion 92a acting through a dashpot 92b. The latter is equipped with a suitable compression spring 92e which is effective to again open thecontacts 91 after the closing thereof a'nd vafterdashpot iuid4 has had suiiicient oppor tunity to ow through'its piston orifice 92d. u

In the event of anV emergency'red button stop, as 'in the case of a web break, for example, it is" desirable that there be immediate application Aoffull braking forcel applied by the belts 44 tothe web roll 14 to preclude over# running thereof and an oversupply of paper to the press. For this purpose a vpush-type solenoid 95 is provided which is controlled by the emergency stop button and which acts directly on the jet pipe 55 of the regulator 46.. This solenoid is effective, upon the linterruption of the supply of electric power to operate the press, to movethe jet pipe 55 into its full tension-increase position so as to produce a full pressure iluid supply tothe tensionincrease chamber 51a of the belt actuator cylinder. 51. Such movement of the jet pipe causes the piston 50 and tension pulley 53 of the actuator to be moved quickly toward their' fully extended positions thereby rapidly l drawing up on the belt 44 so as to apply maximum brak-- ing force to the web roll 14. v

Means is also provided for completely slacking olf on thetension belt 44 if for any reason this is desired, as for example upon initial web threading. For thispurpose, a push-type solenoid 96 under the control of a switch 96a is provided which is mounted on the jet pipe "regulator housing 56. This solenoid is operative to move the Atension control system is extremely sensitive and quickly Y responsive to web tension variations from a normal setting to compensate therefor; lt might be thought that because of the slight time delay inherent in any system of this general type between the sensing of a Variation in web tension and the actual compensation therefor,

' there would be a tendency for an oscillatory condition or hunting about the control point to obtain. It has been found, however, that any such tendency toward hunting hasv been entirely eliminated. Observations show that this is attributable to the restricted communication pro vided between the tension-decrcase supply line 68 and the Y sump return line 62 so that the majority of pressure uid directed by lthe regulator 46 toward the tension-decrease chamber 51b of the belt actuator 42 is returned to the sump 60. Thus while the belt actuator operates rapidly and with full force to compensate for a decreasein running web tension, the operation in the opposite direction, though equally quick, is of substantially less force, it being only necessary to slack olf on the belt 44 so that the momentum of the running web roll is permitted to supply paper at a faster rate with a resulting decrease in web tension.

By way of summary, the press operator adjusts the pressure tluid regulator valve 81 so that the .desired norl mal web tension obtains as indicated by the gauge 82.

As long as the web tension remains constant the floating roller actuator'ZS-holds the oating rol1er40 in its normal central position. As ,a resultthe jetpipeSS loftheregulator 46 is alsoheld in. its centralV position and the supply of pressure uid therefrom is divided substantially equally between the two outlet orices 65 and 66. Therefore, no movement of the belt actuator piston 50 occurs, and the braking force exerted by the tension belt 44 on the web roll remains constant. Should there be a decrease in running Web tension the iioating roller actuator 78 operates to move the floating roller 40 to the right as shown in Fig. 2. This produces a corresponding movement of the push pin 73 to move the jet pipe 55 into its tensionincrease position whereby to direct the iiow of pressure liuid therefrom into outlet orifice 65, and thence by way of the. supply line `67 to the tension-increase chamber 51a of the cylinder 51` of the belt actuator 42. As a result, the piston 50 and tension pulley 53 of the actuator are forced outwardly to cinch-up on the tension belt 44 with the result that an increased braking force is applied to the running web roll 14 thereby increasing the tension in the running web as it is drawn into the printing press.

As soon as the tension increase is effected, there is a corresponding pull by the running web W on the floating roller 40 to move it to the left as shown in Fig. 2 with the result that the jet pipe 55 is moved from tension-increase position toward tension-decrease position by means of the regulator spring '75. This movement continues until the desired normal running web tension is restored.

Conversely, if there should be an increase in web tension, as would be occasioned, for example, by an increase in press speed, the running web produces a movement of the oating roller toward the left, as shown in Fig. 2, against the action of theoating roller actuator 7S. Such movement permits the regulator follower spring 75 to moveY the jet pipe 55 toward its tension-decrease position. In such position, lpressure uid from the jet pipe is directed into outlet orifice 66 and thence by way of supply line 68 partly to the tension-decrease chamber 51h of the belt actuator cylinder 51, and partly to the drain line 62. As a result, the actuator piston 50 and the tension roller 53 are permitted. to retract whereby to relieve the braking force exerted by the tension belt 44 on the running web roll 14. As a result, less resistance is oiered to the, drawing of the web W from the paper roll 14 into D the printing press and web tension decreases. As the web tension decreases, the floating roller actuator 78 effects a movement of the oating roller 40 and its supporting arm 70 toward the neutral or central position, such movement eiecting a return of the jet pipe toward its central position as the desired normal web tension is restored.

From the foregoing, therefore, it will be apparent that a webtension control system constructed and arranged in accordance with the present invention is extremely seni iii) sitive tochangesin running 'web tension and is `quickly responsive'tocompensate for Stich changes without, however, being susceptible to hunting or oscillation by over and under swinging about -a desired normal tension setting.

The present system is free of all of the disadvantages inherent .in prior tension controls embodying shock absorbers, springs and weight-inertia tension sensing and control devices. The instant system wherein tension is controlled by means of hydraulic pressure iluid is exceedingly simple in construction and, therefore, permits of conornical manufacture. Complete tension control over a wide range can be effected solely by adjustment of a single pressure uid regulating valve. Since the entire system is hydraulic in nature and no minute-sized apertures or orifices are necessary, there is little chance of dirt, lint or the like causing a failure. Furthermore, ,it is readily adaptable to installation in connection with any of the currently used web fed printing presses.

'i claim as my invention:

ln a tension control system for maintaining a desired tension in a running web fed from a paper roll, the combination comprising a brake belt peripherally engaging the roll to apply a braking force thereto, a double-acting pressure liuid actuator connected to said belt for tensioning and slacking off the latter, a source of pressure fluid and a sump, a pressure uid regulator supplied by said source and having a movable jet pipe for applying iiuid to the ends of said actuator alternatively in accordance with the position of the jet pipe, a floating roller for engaging a loop in the running web, means for mounting said roller for bodily movement in response to changes in loop tension, means for biasing the roller in a direction to elongate the loop, and means for coupling the jet pipe in the regulator to said roller so that a departure .in loop tension from the desired value causes movement of the jet pipe to produce a corrective change in braking force, the end of said actuator employed for slacking off having a restrictcd connection to said sump;

References Cited in the file of this patent UNITED STATES PATENTS 1,544,684 Roesen July 7, 1925 1,636,987 Cline et al. July 26, 1927 2,155,431 Weiking Apr. 25, 1939 2,200,438 Wood May 14, 1940 2,334,164 Lotz Nov. 16, 1943 -2,336,112 McCleery Dec. 7, 1943 2,343,181 Heinz Feb. 29, 1944 2,518,575 Stobb Aug. 15, 1950` FOREIGN PATENTS 362,945 Great Britain Dec. l1, 1931 471,090 Germany Feb. 9, 1929

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