US2972297A

US2972297A - Multicolor printing on a continuous web

Info

Publication number: US2972297A
Application number: US688034A
Authority: US
Inventors: George N Auerbacher
Original assignee: CHAMPLAIN CO Inc
Current assignee: CHAMPLAIN CO Inc
Priority date: 1957-10-03
Filing date: 1957-10-03
Publication date: 1961-02-21
Anticipated expiration: 1978-02-21

Description

Feb. 21, 1961 a. N. AUERBACHER 2,

MULTICOLOR PRINTING ON A commuous WEB Filed Oct. 3, 1957 34 mg 96 5 .22 /02 A90 nited States MULTICOLOR PRINTING ON A CONTINUOUS WEB George N. Auerbacher, Springfield, NJ assignor to Champlain Company, Inc., Bloomfield, N.J., a corporation of New York Filed Oct. 3, 1957, Ser. No. 688.034

Claims. (Cl. 101-481) individual units of the press line driven by said shaft.

Thus, additional motion or velocity may be added-or subtracted at any unit to keep it in proper registration. To do this at high web speeds, photoelectric scanners have been devised which are located between units, and which automatically feed positive or negative motion at'the running register, as may be required to maintain registration. Other expedients for this purpose are employed, such as movable compensator rollers which slightly lengthen or shorten the web between one press and the next.

In a multicolor press, the printing cylinders theoretical- 1y all have the same diameter, and it has been assumed that in such case the unit of printing matter or so-called layoff would be constant, and that departure from registration arises from variables such as web stretch or yield; minute changes in the web drive velocity at the printing cylinder; minute differences in cylinder diameter, etc. I have found that the difiiculty may arise from minute differences in the length of printed matter or layoff which may occur even at a single printing cylinder of unquestioned constant diameter. An object of the present invention is to overcome suchdiiferences, and maintain uniform layofi of the printed matter on a web, particularly when dealing with a comparatively thick web.

This helps maintain registration, and the object of the invention may be defined more broadly as being to maintain registration of multicolor printing. In theory, one might eliminate running registers, but inasmuch as the uniform layoff of my invention presupposes perfect initial registration, and inasmuch as running registers are anyway convenient, and almost a necessity to secure initial regis tration, my invention in preferred form is used along with running registers, and serves to minimize the work which must be done by the running registers.

Web scanners are employed to detect any departure from uniform layoff, and in accordance with a further feature and object of my invention, the same web scanners may be employed for both purposes, that is, to help restore uniform layoff in the event of a departure from uniform layoff, and to help restore registration in the event of a departure from registration.

To accomplish the foregoing general objects, and other ice Fig. 1 is a plan view of a multicolor printing press enibodying features of my invention;

Fig. 2 is an elevation of the same;

Fig. 3 is a schematic elevation of a part of the press. shown in Fig.2, drawn to enlarged scale; and

Figs. 4 and 5 are companion fragmentary views explanatory of the underlying principle of the invention.

Referring to the drawing, and more particularly to Fig. 3, the right hand unit of the printing press there shown is of the intaglio or rotogravure type. It comprises an engraved printing cylinder 12, and a cooperating impression cylinder 14. Cylinder 12 is inked in any desired fashion, as by use of an ink fountain 16, 'and the excess ink is scraped from the cylinder by a suitable doctor blade, schematically represented at 18. The web 20 is passed between the cylinders 12 and 14, and the underside thereof receives ink from the engraved impressions in the cylinder.

The web is then dried by passing the same through a suitable drier, indicated at 22, following which it is led to the next printing unit.

Referring now to Fig. 4 of the drawing, the printing cylinder 12 may be assumed to be conventional in that it is made of a non-yielding material, specifically metal, which is chemically etched to form the intaglio impressions therein. The impression cylinder 14 also is conventional, in at least to the extent that it is made of a yieldable material, typically rubber or its equivalent, as shown at 24. 'The web 20 is shown approaching the cylinder 12 in a downwardly sloping direction at 26, and leaving the cylinder 12 in an upwardly sloping direction at 28. In other words, in Fig. 4 the web 20 is wrapped partially around the impression cylinder 14, and it is convex in relation to the printing cylinder 12. If the web has significant thickness, the upper surface is contracted, and the lower is stretched, relative to the mean or pitch length of the web indicated by the broken line 30.

The printing cylinder 12 applies printed matter to the underside or stretched surface of web 20, and on reflection it will become evident that when the web is subsequently straightened or laid flat, the printed matter will be slightly contracted. The layoff on the web then will be slightly less than the circumference of the printing cylinder 12.

Referring now to Fig. 5, assumes that the web is wrapped partially around the printing cylinder 12, as shown in broken lines, that is, it approaches the cylinder in upwardly sloping direction as shown at 32, and leaves the cylinder in downwardly sloping direction, as shown at.

34. Differently expressed, the web is concave in respect to the printing cylinder 12. Here again, one face of the web is stretched, and the other contracted, relative to the pitch line, but in opposite sense from what is shown in Fig. 4. Thus, when the web is subsequently straightened or laid flat, the printed matter on the bottom face of the web will be stretched or lengthened slightly, and the layoff will be slightly greater than the circumference of the printing'cylinder.

Now, in practical apparatus of types already in common use, including the type illustrated in Figs. 1-3, it would not be convenient to keep changing the angle of approach and departure of the web from the printing cylinder. However, I have found that for purposes of the present invention, this may be done in effect, by

' changing the pressure exerted on the web by the impression cylinder. This is so because of its yieldable nature, and referring to Fig. 5 of the drawing, the web 20 shown in solid lines approaches and leaves the printing cylinder 12 in downward and upward sloping directions, 26

and 23, exactly as in the case of Fig. 4, but increased pressure between the cylinders has caused a surface C0117 tact instead of a line contact with the printing cylinder at 36, resulting from compression or yield of the material of -the impression cylinder at 38. The portion of sprees? the. web immediately atthe. printing cylinder is concave rather than convex in respect to the printing cylinder, and this is so despite the slope of the Web at 26 and 23.

Thus,=a variation in pressureexerted on theimpression cylinder is equivalent to:a:change :in TWebrdlICCtlOl'I; or in convexity versus concavity; relativeqtou the? printing cylinder. Thisin turn causes. achange inwlayoff of the printed matter on the .web, andrthusthe pressure .ofthe impression cylinder may be usedntozvary, therlength of the layoff in one direction orthe other;

Reverting. now to Fig. 3 .of the drawing, theapparatus includes a'pressure exerting means Atlwtoexert pressure oncthetweb between the cylinders.12 and 14ft ltsfurther comprises .a. detector means 110, .44; :46:to:1deteet any departure'ifro-m uniform layofizof'fthe .printedi-matter, and .further comprises: means;48 and: t) :for varying :the pressure'exerted' on the. webaby, .the;means.;40:in: that direction-which tends to restore uniformclayofil't Considen'nglhe :invention in greatercdetail, .andrreferring: more; particularly to "Figsa l and. 2,. web; so is: 1111- wound vfrom.a..large reel.54, and:.then;passed through appropriate. units such as. a splicer. 56,-decurler 53 and.

pull unit 66. The roll 54 maybe-amounted :onta roll carrier 62: designed to facilitate changingv from one roll as it expiresto a new roll, shownatdS. The expired roll may thenbe removed and replaced by. another full rollJpreparatory to expiration of thesecondroll, and

so one The: web feed or. pull unit .69 is'arrangedfor fine speedadjustment, as: by a means of an infinitely variable drive'64. There is usually a slack loopofi ahead of the feed unit. 66. The web .thengoes to a series of units for multipleoperations on the'web. Inthe present case, a multicolor gravure'press is shown,.comprising printing units 71 72,74, 76 and 78, These are. followed by a pull unit 80, which may-befollowed by still further units, not shown; for:scoring, creasing, punchingor/an-d cutting the web.

Referring to Fig.1, theiunits of the press line, and bothpull units, are all driven in unison by a common drive .shaft 82driven by a-motor 84 through suitable belts 86'. The gearing between theshaft 82- and the gravure cylinder shafts is shown at 90, 92, 9 5, 96, 98, respectively. This ordinarily includes running register mechanism of the differentialgear typ'e, so that additional motion may-be'fed in bymeans of remotely controlled reversible acorrection motors, indicated at Mill, 102,- 1d4, 106 and108; Running register Qtl'and correction motor 1% onthe first --unit 7tl are not essential, but maybe usedfor'convenience and uniformity. The differential gear-running registers need not be described in detail, for they are well known inthe art, and referencealsomaybe made to U.S. Patent No. 2,163,035 issued'to' William FJGrupe on June 20, 1939, and entitled Apparatus for Ellecting Register of Multiple Operations.

To automatically control the registration correction motors, the web may bescanned by suitable scanners housing photoelectric cells or eyes, indicated in Fig. 2 at 110, 112, 114 and 116. These form part of a registration control apparatus which may be of the type disclosed in US. Patent2,348,862 granted to Morris Sorkin on May 16, 1944 and entitled Registration Control Apparatus. In that apparatus, the position of a mark on the web is compared or related to the position of a mark on the print cylinder shaft, and for this purpose, each print cylinder shaft is provided with a socalled phase detector unit. These are indicated in Fig. l at 122, 124, 126 and 128. Such units (scanner and phase detector) are not needed 'for'the first press unit 70, because the problem is to keep the subsequent units inregistration with the first unit.

' In lieu of comparing the'position of a mark put: down on the web by the first'unit, with the position of a mark on the second cylinder, it may lac-compared with; a sec- 0nd mark put down on the web by the second cylinder (which, of course, is an indication of the position of the second cylinder). Such a system is disclosed in US. Patent 2,151,570 granted March 21, 1939 to D. R. Shoults 'et al. and entitled Control System. For pur poses of the present invention; there is some difference between a system using scanners to compare two marks on the web, and a system: comparing a single mark on the web with a phase detector. Either system will control a correction motor to add motion to the drive :of a unit, and thus speedsitqor. .slows.it:.sligl1tly. in. order 1 to hold it in register.

structurally, there would be a. difference in the addition of another scanner following the last printing unit 78, this being indicated..'at-118.in;Fig. 2. This added scanner 118 would replace the phase detector shown at 128 in Fig. 1. In passing, it maybe mentioned that even" with. phase: detectors, the; webfscanners. may be located: (though .less, desirably), followingtheircrespec'- tive phaseizdetector, instead: of preceding thesame, in which case the scanners 112 through 118.would-;be used withthe phase;detectorsz122=128z The :disadv'antageis that; the; comparison for .registration and the resulting correctiontare' madelater, after an additional length: of.

webcorresponding toLthat .usedin one;printing.unit.;. In any event, the phase'detector system ismoreconvenient here,xbecause;a phase:detectoniszneeded. on at leastthe first unitfor layoff lcontrol...

Referring to Fig. .2,,.feed.unit 60 .is followedby. a dancer roll .130;- This is gievenvia.weightizcorresponding to double the desiredweb tension, oriit may be'rnadeof excessive weightiand thenrcounterbalanced .by. springs. or a weight arm', (no shown. The .dancer roll: 13%. is anounted for vertical movement, and may 'be.:provide'dwith limit switches, notrsh'ownn Theinfinitely variable .drive' 64 is driven by shaft 32,.but-has a =remotely:controlled. reversible adjusting'rnotor. 132,1 an'd the limit switches at dancer-roll 130 are connectedtomotor 132. The feed velocity'is increased when" the danceriro'll- 130 rises, and is decreased. when-itfalls; in orden to keep the dancer. roll suspended at 'an intermediateI.-point; where: its weight determines thetension of :the W61); Theielement 132lmay behydraulic,in which case-its valves.are'electrically controlled, with the same end result.

As se ler-described, theapparatusishown'in Figs. 1 and 2 may be conventional. lthas: long been the practice v.and understanding of the industry that the pressure exerted on and by impression cylinders should be maintained constant. Contrary to'this prior practice, I have found that the maintenance of registration is greatly aided by varying the pressure applied onthe' web J by the impression cylinder in such directionias: to .maintain con stant layoff of'the printedmatter on theweb...

Referring to Fig. 3, a web'scanneris located between the printing press unit 70, and the succeeding press unit 72. i The printed matterrputonthe web by cylinder 12*includes a marker or target, and this is repeated a number of times along the web until the Web scanner 11% is reached. The position ortiming. of the: target is related to the position or timing of thecylinder 12, .by use of a so-called phase detector rotating With cylinder 12. This is schematically shown-M in Fig.1, and in Fig. 3 is schematicallyrepresentedby a targeti tS on the cylinder cooperating with'a photoelectric eye- 4-4. The web scanner 110' is connectedt to apropriatecircuitry housed at 46, and the eye44=is also connected to the circuitry at46. The arrangement may be exactly like that used for registraiton cont-rol, as=disclosed:in the aforesaid Sorkin Patent"Nor-2,348;862. The output of the circuitry at id may be used to-"control-a remote reversible correctionmotor 48. This-inturmisused to vary the'ad justment of 'a pressure-regulator-Si), and -thus to vary the pressure exerted by the impression cylinder It will be understood thatin' practice the hydraulic cylind l' 40-may be made double acting instead ofsingle I acting as shown, with appropriate values to afford lifting of the impression cylinder under manual control when desired. In some systems, the impression cylinder and its associated bearings etc. may be heavier than the desired pressure on the web, and in such case, the hydraulic cylinder 40 may be double acting in order to lessen the effective weight of the impression cylinder, in-' stead of adding to it. Other ways to vary the pressure of cylinder 14 may be used, such as compression springs in lieu of the hydraulic cylinders, with a reversible correction motor, reduction gearing, and screws to raise or lower the stationary ends of the compression springs, and thereby vary the pressure exerted thereby.

Whatever mechanism is employed for the purpose is preferably duplicated in each of the printing units. Thus, the impression cylinder 138 is' controlled by hydraulic cylinder 140 and pressure regulator 150, the latter being adjusted by a correction motor 148 which in turn'is controlled by a web scanner 112, and a phase detector 122 operating 'jointly through circuitry housed at 146. Similarly in press unit 74, the impression cylinder is controlled by web scanner 114 and phase detector 124 connected to circuitry housed at 156 and controlling a remote correction motor 158. Similar remark applies to press

units

76 and 78 not shown in Fig. 3, but shown in Figs. 1 and 2.

Two separate scanners may be used between the first and second presses, one scanner for use with the phase detector 120 for layoff control, and one for use with the phase detector 122 for registration. correction. However, inasmuch as a single scanner may be wired to both circuits or control panels, I here show one scanner at 110, serving both purposes.

Referring to Fig. 3, the first web scanner 110 is connected not only to the circuitry housed at 46 to maintain uniform layoff, but also to conventional circuitry housed at 172 which controls a remote reversible correction motor 102. This is the motor also shown in Fig. 1 associated with the running register differential gearing at 92 for feeding positive or negative motion to the printing cylinder of press 72. For this purpose, the web scanner 110 makes its comparison with the phase detector 122 on the next press 72. The phase detector may be of more elaborate construction, such as that shown in Sorkin Patent 2,348,862 previously referred to.

In similar fashion, the web scanner 112 cooperates with a preceding phase detector 122 and the circuitry 146 to control correction motor 148 for uniform layoff, and the web scanner 112 cooperates with the succeeding phase detector 124 and circuitry housed at 174 to control a correction motor 104 which takes care of registration. More specifically, the motor 104 'corersponds to that shown in Fig. 1 on the running register 94 for the press 74. Similar remark would apply to the remaining web scanners and phase detectors, nearly all of which serve a dual function both for uniform layoif' and for registration. a

It is believed that the construction and operation of my improved apparatus, as well as the advantages thereof, will be apparent from the foregoing detailed description. The usual running register mechanism may be retained, and is preferably automatically controlled bythe usual electric eye scanners. These may be of the double marker type (Shoults Patent 2,151,571) or of the single marker and phase detector type (Sorkin 2,348,862). However, even when the double marker type is used,.one phase detector is employed, this being mounted on the first press unit, and serving for purposes of uniform layoff in the could serve in lieu of a target on the cylinder, for pur poses of comparison. v

In general, a register correction afforded by the running registers represents a temporary change in speed at any one unit, to effect a change inposition at that unit, in order to achieve registration. The amount of correctidn thus required is minimized by' maintair'u'ng uniform layoffs at all of the press units, and in accordance with my invention, this is done by appropriately varying the pressure exerted on the web by the impression cylinders in proper direction to maintain the desired uniform layoff.

It will be understood that while I have shown and described my improved apparatus in a preferred form, changes may be made in the structure shown, without departing from the scope of the invention, as sought to be defined in the following claims. In the claims, the terms marker or target are intended to include a selected part of the desired printed matter, as well as a marker used solely as a target. The reference to the web being comparatively thick means merely that the web is thick enough to result in a diiferencebetween the pitch length and the lengths of the inner and outer faces, which difference is sufiicient to make possible a layoff correction by pressure control as here taught.

I claim:

1. In the operation of a multicolor printing press working on a continuous comparatively thick web, with each unit of said press having a printing cylinder made of conventional non-yieldable material, and an impression cylinder made of conventional yieldable material, said cylinders exerting an operating pressure on the web, the method of helping maintain uniform layoff and registration of the colors, which includes putting 'a marker on the web in .a first printing unit, scanning the marker between said first and a second printing unit to measure the position of the marker after a number of repeats of the marker in order to detect a change in layoff, and varying the pressure exerted in said first printing unit on the web between the printing cylinder and the impression cylinder in that direction'which helps eliminate a departure from the desired uniform layoff While maintaining a minimum pressure sufficient to pre vent slippage between the printing cylinder and the web.

2. In the operation of a multicolor printing press working on a continuous comparatively thick web, with each unit of said press having a printing cylinder made of conventional non-yieldable material," and an impression cylinder made of conventional yieldable material, said cylinders exerting an operating pressure on the web, the method of helping maintain uniform layoff and registration of the colors, which includes putting a marker on the web in each printing unit, scanning the marker of each unit between that unit and the succeeding unit to measure the position of the marker after a number of repeats of the marker in order to detect a change in layoif in each said preceding unit, and varying the pressure exerted on the web between the printing cylinder and the impression cylinder of each said preceding unit in that direction which helps eliminate a departure from the desired uniform layoff in the said preceding unit while maintaining a minimum pressure sufficient to prevent slippage between the printing cylinder and the web.

3. A printing press for working on a continuous comparatively thick web, said press having a printing cylinder made of conventional non-yieldable material, an imimpression cylinder, said operating pressure being variable but sufficient to prevent slippage between the printing cylinder and the web, detector means to detect a "first press, where there is nopreceding marker which departure from uniform layoff of the printed matter printed on the web by the printing cylinder, and means responsive to said detector means for varying the pressure exerted on the web by the aforesaid pressure exerting means in that direction which tends to restore unieach having a printing cylinder made-of conventional non-yieldable material, an impression cylinder made of conventional v.yieldable material, an operating pressure exerting means to exertipressurc on the web-between the printing cylinder and the impression cylinder, said operatingtpressure being variable but sufiicient-to prevent slippage between the printing cylinder and the Web, detector means to detect a departure from'uniform layoff of the printed matter printed on the web by the printing cylinder, and means responsive to said detector means for varying the pressure exerted on'the web by the aforesaid pressure exertin means in thatdirection'which tends to restore uniform layoif in order to help maintain registration of the-colors.

5. -A multiple printing press working on a continuous comparatively thick web, each unit of said press having duced in said first unit, and means responsive to said web scanning means for varying the pressure exerted on the web in said first unit in that direction which helps restore the desired uniform layoff in the said first unit.

6. A multiple printing press working on a continuous comparatively thick web, each unit of said press having a printing cylinder made of conventional non-yieldable material, an impression cylinder made of conventional yieldable material, means to exert an operating pressure on the web between each printing cylinder and its cooperating impression cylinder, web scanning means between a first unit and its succeeding unit arranged to detect any change in layoff of "the printed matter produced in said first unit, means responsive to said web scanning means for varying the pressure exerted on the web in said first unit in that direction which helps restore the desired uniform layoff in the said first unit, a common drive shaft for said units, running register means between said drive shaft and the printing cylinder of the second unit, and means responsive to the aforesaid scanning means to supply positive and negative motion at said running register in that direction which helps restore registration of the matter printed by the different units of the press.

7. A multiple printing press working on a continuous comparatively thick web, each unit of said press having a printing cylinder made of conventional non-yieldable material, an impression cylinder made of conventional yieldable material, means to exert an operating pressure on the web between each printing cylinder and its cooperating impression cylinder, said operating pressure being variable but suflicient to prevent slip-page between the printing cylinder and the web, web scanning means between each unit and its succeeding unit arranged to detect any change in laycif of the printed matter produced in each said preceding unit, and means responsive to each web scanning means for varying the pressure exerted on the web in each said preceding'unit in that direction which helps restore the desired uni-form layoff in the said preceding unit. a

'8. .A multiple printing press working on acontinuous comparatively thick web, each unit of said press having I yieldaole material, means to exert an operating pressure on the web between each printing cylinder and itemoperating impression cylinder, 1 web scanning means between each unit and its succeeding unit arranged to detectany change in layoff of-the printed matter produced in each said-preceding unit, and means responsive to each web'scanning means for varying the pressure exerted on the web in each said preceding unit in that direction whichhelps restore the desired uniform layoff in the .said precedingunit, a common drive shaft for said units, running register 'means between said drive shaft and the printing cylinder of the second and succeeding units, and means responsive to said web scanning means to supply positive or negative motion at said running registers as needed to help-restore registration in the event ofdeparturefrom registration of the matter printed by thedilferent units of the press.

9. A multiple printing press working on continuous comparatively thick web, .each unit of said press having a printing cylinder made of conventional non-yieldable material, an impression cylinder made-ef'conventional yieldable material, means to exert an operating pressure on the Web between each printing cylinder and its cooperating impression cylinder, said opearting pressure being variable but sufiicient to prevent slippage between the printing cylinder and the web, web scanning means between a first unit and its succeeding unit arranged to detect any .change :in layoff of the printed matter produced in said first unit, means responsive to said'weo scanning means for varying the pressure exerted on the web in said first aunitin that direction which helps restore the desired uniform lay-off in the said first unit, a common drive shaft EfOl said units, running register means between said drive shaft and the-printing cylinder of the secondunit, and means responsive to the aforesaid web' scanningmeansto supply positive and negative motion at said running register in that directionwhich helps rest-ore registration of the matter'printed by the different units of the press.

10. A multiple p-rinting'press working on a continuous comparativelythick web, each unit of said press having a printing cylinder made of conventional non-yieldable material, an impression cylinder made of conventional yieldable material, means to exert an operating pressure on the web between each printing cylinder and its cooperating impression cylinder, said operating pressure being variable but sufficient to prevent slippage between the printing cylinder and the web, web scanning means between each unit and its succeeding unit arranged to detect any change in layoff of the printed matter produced in each said preceding unit, and means responsive to each web scanning means for varying the pressure exerted on the web in each said preceding unit in that direction which helps restore the desired uniform layoff in the said preceding unit, a common drive shaft for said units, running register means between said drive shaft and the printing cylinder of the second and succeeding units, and means responsive to the aforesaid web scanning means to supply positive or negative motion at said running registers as needed to help restore registration in the event of departure from registration of the matter printed by the different units of thepress.

References Cited in the file of this patent UNITED STATES PATENTS 1,460,206 a 1923 2,036,835 1936 2,500,230 1950 2,583,580 Ludwig Jan. 29, 1952 2,651,256

Huck Sept. 8, 1953