US2360676A - Cylinder etching machine - Google Patents

Description

0d. 1944- c. L. HENDERSON ETAL ,5

CYLINDER ETCHING MACHINE Filed July 28', 1941 5 Sheeis-Sheet 1 r INVENTO Charles L. fi'rzdefs n Che/view .2? Powers 1944- c. HENDERSON ET AL 2,360,575 CYL INDER ETCHING MACHINE Filed July 28, 1941 5 Sheets-Sheet 2 Fig.2. 09 C INVENTORS: Charles .5. Henderson BY Chesz'er" 16. Powers 00L 1944- c. L. HENDERSON ETAL CYLINDER ETCHING MACHINE Filed July 28, 1941 &

5 Sheets-Sheet '3 o Q m Q INVENTORS! Charles L Henderson BY 6706575297" 1?. Pours/"'6 a1: an L jd d Oct. 17, 1944.

C. L. HENDERSON E'I'AL CYLINDER ETCX-IING monum- 5 Sheets-Sheet 4 I Filed July 28, 1941 III,

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INVENTORS C/wowlies L. Heads Yv W l N w Oct. 17, 1944. L HENDERSON ETAL ,360,676

CYLINDER ETCHING MACHINE Filed July 28, 1941 5 Sheets-Sheet s I I W6)" I I INVENTORS:

Charles L. Hendersom BY t Paws 15 flan/no, 4 I

v Wigs Patented Oct. 17, 1944 V mm ETCHING momma Charles L. Henderson and Chester Powers, Appleton, Wis., assignors .to Paper Patents Company, a corporation of Wisconsin Application July 28, 1941, Serial No. 404,338 12 (oral-9) The present invention relates particularly to apparatus and methods for etching intaglio or relief printing cylinders.

In intaglio printing the printing surface comprises a smooth, metallic surface, usuallyof copper, havin formed therein, by etching or otherwise, symmetricall'y arranged ink-receiving recesses of very small area. The ink recesses throughout the printing surface areseparatedby line-like, unetched lands, which serve to support the doctor or scraper blade used for removing excess ink from the printing surface during the actual printing operation.

During the manufacture of intaglio printing cylinders, it is customary to employ a light sensitive film or resist, which asmanufactured is soluble in water or other solvent but which becomes insoluble when exposed to light, and to transfer the image or design to be reproduced to the resist photographically. The resishmay be formed upon the surface of the metallic plate orcylinder by application thereto in liquid form, or it may be in the form of a sheet, such as carbon tissue, which is wrapped around the printing cylinder or otherwise applied to the surface after the transfer operation, as in the rotogravure process. The image or design which is to be reproduced in the printing surface is broken up into small opaque dots, either before or during the transfer operation. The line-like areas between the opaque dots are exposed to light during the transfer operation, and the resist in those areas is rendered insoluble.

Following the transfer operation, the resist is washed, to either partially or wholly remove the unexposed dot areas, and is hardened. The surface is then etched by iunnersion in a suitable etching fluid or other procedure. During the etching the light insolubilized, line-like areas of resist intermediate the dot areas protect the lmderlying portions of the; printing surface from 1 the etching fluid, and as a result the etching takes place only in the unexposed dot areas which ished printing plate.

The manufacture of relief cylinders may follow a similar process. as is knownin the art.

'lnthepas'hdifficultyhasbeenexperiencedin effecting completely satisfactory etching of cylin- 35 .6 is a fragmentary perspective view illus-j areas which are different in tone from the main body of the etching, the efiect being known as shading. p Y

The principal object of the present invention is to overcome this difiiculty which is inherent in the prior art etching procedures, and to provide amachine and method whereby uniformly etched surfaces, free from shading, can be produced by a. relatively simple etching operation. It is also an object of our invention to provide an improved etching machine, particularly adapted for etching printing cylinders, which can be operated to produce a very uniform etch of excellent printing characteristic. Other objects and the various advantages of the invention will be made apparent by reference to the accompanying drawings and the following description of one preferred embodiment thereof. In the drawings:

Fig. 1 is an and elevation of an etching machine constructed in accordance with the present invention; I a

Fig. 2 is'a-sectional view of the machine illustrated in Fig. l, the view being taken on the line 2'2 of that figure;

Fig. 5 is a fragmentary sectional view-showingthe details of one of the resilient bearing supports for the sealing rolls forming a part of the machine illustrated in the other figures of the trating one means of adapting the apparatus of the other figures'of the drawings for use in connection with short rolls;

Fig. 'l is a sectional view, generally similar to 40 Fig. 4, of a modified form of the apparatus of Fig. 7. thereby become ink-receiving recesses in the fin the present invention; and

Fig. 8"is a sectional view on the line 8-8 of Referring particularly to Figs. 1 and 2, the apparatus therein illustrated includes a rectgns'u- .larly-shaped outer tank ll of relatively haw,

reinforced, wood construction whichis supported upon four uprights l3 and a rigid, metallic frame l5,

wallsmaybesplashedwith acidor other etching fluid, the wood of which the tank Ills constructed should be impregnated or painted with anacid-resistlng compound.

The etching fluid is contained within a. boxlike container or tank l1, preferably made of wood'whichhas been coated or otherwisetreated torender it acid-resistin Thetank I1 is suppcrtedadjacent-theopentopofthemaintank- Theoutertankllisopenatthetopandserves to contain the other elements of the ap Because of the possibility that the tank II by means of suitable hollow support members N) (Fig. 3), having bracket portions 2| afflxed to the two ends of the main tank II by suitable lag screws 23, as illustrated. The acid or other etching fluid is applied to the surface which is to be etched by means of a rotatable impeller member 25 and an impeller housing 21 which cooperates therewith. The impeller housing 21 comprises an elongated, open-mouthed, rigid vesvel'having the general outline illustrated in Figs. 4 and 6. It is bolted to one of the support members l9 at each of its ends, and thereby supported in proper position within the tank l! for the etching fluid. The impeller housing 21 comprises two complementary half sections of cast iron which are bolted together by suitable bolts 28. The housing 21 is coated with acid-resisting material and is open along its lower edge, as illustrated at 29, to permit free entry of the etching fluid thereinto. a

The impeller 25 of the apparatus illustrated in the drawings comprises a series of paddle members 3| made of an acid-resisting plastic, such as that sold under the trade name of Lucite, or of some other acid-resisting material, which are affixed to a suitable rotatable shaft 33., One end of the shaft 33 extends through an opening 35 in the main tank I I, as illustrated in Fig. 3, for connection to amotor 31 (Fig. 2) or other rotating means.

I The impeller 25 is supported for free rotation within the impeller housing 21 by suitable bear-' ings 39 (Fig. 3), which in turn are supported in the hollow support members l9. To prevent acid carry-over into the bearings 39 during the operation of the apparatus, a labyrinth seal 4| is provided at each end of the impeller housing 21, and this is backed up at each end of the machine by a gland seal 43. The motor 31 which is used for rotating the impeller 25 is supported upon a bracket 45 aflixed to the adjacent end of the main tank H and is connected to the impeller shaft 33 by a belt 41 and suitable pulleys l9 and A variable speed motor is preferred.

In order to confine the etching fluid which is discharged through the mouth 53 of the impeller housing 21 by operation of the impeller 25, the machine is provided with two longitudinally-extending sealing rolls 54 and 55 which are supported for free rotatable movement by means of central shafts 55 and spaced bearings 51 which form a part of the support members l9. The sealing rolls 54 and 55 are identical in construction and should be made of fairly soft, acid-resisting rubber or rubber compound. Rolls of sufficient -softness to give a plastometer-reading of about 140 with a /4 inchball have proven particularly satisfactory. To prevent acid from being carried into the supporting bearings '51 for the sealing rolls, the bearing supporting struc ture includes a liquid deflector 59 anda gland seal 8 l as shown in Fig. 3.

Printing cylinders vary considerably in length and in diameter, and a satisfactory etching machine should include means for accommodating cylinders of varying dimensions. In the particular machine illustrated in the drawin s, this means includes an adjustable bearing support structure for the cylinder which is to be etched.

This structure includes a hydraulic operating mechanism 63 (Figs. 1 and 2) having a movable which is mechanically connected to' a piston 65 longitudinally-extending beam 51, a pair of vertically movable supports, one of which is located at either end of the apparatus, and means {or 15 mechanically interconnecting the supports so as to assure uniform movement thereof in response to movement of the hydraulic piston 65 and the beam 61. Each of thev'ertlcally movable supports includes a yoke 63, which is rigidly afiixed to an upper crosshead ll. Theupper crosshead 1| is bolted to two spaced, cylindrical guides 13 which are supported for slidable vertical movement in suitable spaced guideways 15 and I1 rigidly affixed to either end of the main tank II. To limit the downward movement of the vertically movable supports, and for other reasons, a second crosshead member 19 is keyed to the two cylindrical-guide members 13, as illustrated in Figs. 1 and 2. The lower crosshead member 19 at the right hand end of the apparatus (Fig. 2) has afllxed thereto a platform 8] which serves as the support for a motor 83. This motor 83 may be connected to ,the shaft 85 of the cylinder being etched by a suitable belt. 81 and pulleys89 and 9| for the purpose or rotating the, cylinder during the etching operation. To permit free rotation of the printing cylinder during the etching operation, suitable ball bearings 93 are placed over the ends of the shaft 85 of the cylinder. These bearings 93 rest on the yokes 59, as illustrated, 1

Each of the lower crossheads 19 i adjustably connected to one end of the longitudinallyextending beam 61 by means of a'rod member 95, having a threaded portion 91 at its lower end, and a pair of adjusting nuts 99. To assure equal uniform movement of the two vertically adjustable supports for the printing cylinder, each of the rod members 95 extending between the lower crossheads I3 and the beam 61 is provided with two diametrically spaced rack sections HM, and the pair of rack sections on each side of the machine are interconnected by a transverselyextending shaft I03 and suitable pinion gears I05 keyed thereto. The shafts I03 are rotatably supported on the main frame l5 of the machine by rigid bearings llll (Fig. 2).

Fig. 5, include a rigid guideway 3, a cylindrical bearing support member 5 located in said guideway and movable in a vertical direction relative thereto, aspring II! which normally biases the bearing support member H5 (and the bearing) in an upward direction, and a tension adjusting means I IQ for the spring I 11. During the operation of the apparatus, the vertically adjustable supports for the cylinder to be etched will be lowered by the operation of the hydraulic operating mechanism 83 until the cylinder resiliently engages and seals with the sealing rolls. The sealing pressure can be readily controlled by adjusting the tension of the spring H1.

During the actual etching operation it is de sirable that the printing cylinder which is to be etched should be rotated at a relatively slow speed, and tests indicate that cylinder speeds within the range of from about 10 to 12 R. P. M. are particularly satisfactory for etching copper surfaces with perchloride of iron. The impeller I leakage or discharge of the etchin fluid from the.

space between those rolls and the encompassed portion of the cylinder whichis being etched. At

the same time, the sealing roll 55 acts to doctor off excess etching fluid from the cylinder as it rotates, and prevents any substantial quantity of that fluid from remaining on the cylinder after it passes the sealing roll. To prevent any carryover of etching fluid on the other sealing r'oll'54, the apparatus includes a longitudinally-extending rubber doctor I2I which is supported upon the adjacent edges of the tank H for the etching fluid, as illustrated particularly in. Fig. 4. The

v doctor I2I continuously returns any of the etchin fluid which may accumulate on the sealing roll 54 to the main body of the etching fluid contained in the tank II. A longitudinally extending sealing doctor I23, also supported on the tank". engages the lower surface of the sealing roll 55 to prevent discharge of the etching fluid along that edge of the tank.

When the etching operation has been completed it is usually desirable to wash oil the etching fluid as quickly as possible. To facilitate this operation the apparatus includes a pivotally supported metallic apron or deflector I25 which is of such design that it may be swung into place from the inoperative iposition illustrated in full in Fig. 4 to the operative position illustrated by the dotted lines of that figure. In its operative position the apron I25 covers the sealing rolls 54 and 55 and the space therebetween which would otherwise open into the etching fluid tank I'I. Before moving the apron I25 into place, it is of course necessary to raise the cylinder to a position a'bove that occupied by the protective apron. and th s is accomplished by operation of the hydraulic elevatingmechanism 63 for the cylinder supports. The elevated position of small and large cylinders are illustrated by the dotted outlines of Fig. 4. Following the elevation of the. cylinder and the movement of the apron to operativeposition, the cylinder can be washed immediately by a hose or other means without'risk of diluting or contaminating the etching fluid. The washing liquid will be collected in the main tank from which it can be conveniently discharged.

When etching relatively short cylinders, it will atomizing structure I21, as illustrated, includes a pair of complementary, machined plate members I29 which are designed so as to provide a plurality of regularly spaced atomizing jet cham bers I3I which open into wedge-shaped throats I33 wherein are disposed deflector members I35 for dividing and directing the atomized stream so as to assure full coverage at the open upper end of the throat. The complementary plate members I29 are bolted together and are held 'in place within a suitable tank I'I'-A for the adjustable support means for the cylinder which is to be etched are exactly the same in this apparatus as in the previously described structure.

Doctors I2 I-A and I23-A similar to the doctors HI and I23 are provided for preventing excess etching material from being carried around on the,sealing rolls 54 and 55.

Tests have shown that-the etching apparatus which has been described in the foregoing is capable of producing gravure cylinders which are substantially completely free from shading or other defects. Apparently because the etching fluid is continuously applied to a portion of the rotating cylinder and is continuously doctored off at the edges of such portion, the etching operation takes place very uniformly and is capable of easy and convenient control. This accomplishes the highly desirable function of making it possible to carry out the etching of printing cylinders conveniently and. efficiently.

It will be apparent that the apparatus and methods described in the foregoing can be used be found desirable to partially cover both ends of the impeller housing with an acid-resisting, removable cover I 21, as illustrated in Fig. 6. c This arrangement confines the discharge ofthe etching fluid to the length of the cylinder which is'to be etched. j

The modified form of the apparatus illustrated in Figs. 7 and 8 is essentially similar to'the machine which has been described in the foregoing, with this one important exception: In-the modifled apparatus, the etching fluid is directed against the surface to be, etched by means of a liquid jet atomizing structure I21 which is operated by a plurality of spaced air jets. The

by the prior .art and the express language thereof.

We claim: 1. In combination in apparatus of the class described, a cylinder, a pair of spaced horizontally-extending sealing rolls which contact said cylinder, and spray means operable/ to provide a spray of etching fluid which is directed onto thatportion of the surface'of said cylinder which is between said sealing rolls. I

2. In combination in apparatus of the class described, a cylinder, a pair of spaced, generally parallel, horizontally-extending sealingmembers which resiliently contact said cylinder ing the operation of said apparatus, spray me s operable to provide a spray of etching fluid which is directed onto that vportion of the surface of said cylinder which is between said sealing members, and means for moving said surface through said spray during the etching operation. 3. In combination in apparatus of the class described, a cylinder, means for supporting said cylinder for rotation about its longitudinal axis, means for rotating said'cylinder during the opoperable to provide an elongated, relatively narrow spray of etching fluid which is directed onto the surface of said cylinder along the length thereof, and means including a pair of spaced, generally parallel, longitudinally-extending rolls which contact the surface of said cylinder at either side of said spray for restricting the area of said cylinder which is contacted by said spray and for continuously doctoring off the etching fluid from the cylinder surface as it passes out of said spray.

5. In combination in apparatus of the class described, a printing cylinder, an elongated, boxlike tank which has an open top and which contains a quantity of etching fluid, means for mentioned means including an elongated, boxlike tank which contains a quantity of etching spaced, generally parallel, horizontally-extending supporting said cylinder for rotation adjacent the open top of said etching fluid tank, means for rotating said cylinder, means located within said etching fluid tank which is operable to provide an elongated, relatively narrow spray of etching fluid and to direct said spray onto the adjacent surface of said cylinder along the length thereof, and means for continuously doctoring ofl. the etching fluid from the cylinder surface as it passes out of said spray.

6. In combination in apparatus of the class described, a printing surface, horizontally-extending support means for said surface, and means operable to provide a spray of etching fluid which is directed onto said surface to eflect the etching thereof, said last-mentioned means.

including an elongated, box-like tank which contains a quantity of etching-fluid, an elongated impeller housing located within said tank, and a rotating impeller located within said impeller housing, said impeller housing having an elongated, relatively narrow throat through which the etching fluid is directed onto said cylinder.

'7. In combination in apparatus of the class described, a printing cylinder, means for supporting said cylinder for rotation about its longitudinal axis, means for rotating said cylinder, and means operable to. provide an elongated, relatively narrow, spray of etching fluid which is directed onto the surface of said cylinder along the length thereof, said last-mentioned means including a rotating impeller, and anelongated impeller housing within which said impeller rotates, said impeller housing having an elongated, relativelynarrow throat through which the etching fluid is directed onto said cylinder.

8. In combination in apparatus of the class described, a printing surface, a pair of spaced, generally parallel, horizontally-extending sealing rolls upon which said surface rests during the operation Of saidv apparatus, and means operable to provide a spray of etching fluid which is directed onto that portion of said surface which is between said sealing rolls, said lastsealing rolls, each having a resilient outer surface upon which said cylinder rests during the operation of said apparatus, means for rotating said cylinder and thereby also rotating said sealing rolls, and spraymeans operable to provide a spray of etching'fluid which is directed onto that portion of said cylinder which is between aid sealing rolls, said sealing rolls continuously octoring off the etching fluid from the cylinder surface as it passes out of s id spray.

10. In combination in a paratus of the class described, a printing cylinder, vertically adjustable means for supporting said cylinder for ro-- tation about its longitudinal axis, a pair of spaced, generally parallel, horizontally-extending sealingrolls, each having a resilient outer surface upon which said cylinder rests during the operation of said apparatus, means for rotating said cylinder and thereby also rotating said sealing rolls, and means operable to provide an elongated, relatively narrow, spray of etching fluid which is directed onto that portion of said cylinder which is between said sealing rolls, said spray providing means including an, elongated, box like tank which contains a quantity ,impeller housing having an elongated, relatively narrow throat through which the etching fluid is directed onto said cylinder.

11. In combination in apparatus of the class described, a printing cylinder, a pair of spaced, generally parallel, horizontally-extending sealing rolls upon which said cylinder rests during the operation of said apparatus, means for rotating said cylinder, and means operable to provide an elongated, relatively narrow spray of etching 'fluid which is directed onto the surface of said cylinder along the length thereof, said last-mentioned means including a plurality of spaced jet type atomizing nozzle mechanisms and a source of pressure air.

12. In combination in apparatus of the class described, means for supporting a cylinder to be etched for rotation about its longitudinal axis, means for rotating said cylinder during the etching operation, spaced, horizontally-extending sealing members which are adapted to engage the surface of said cylinder along elements thereof to provide a restricted longitudinal pe-. ripheral area on said cylinder exposed to the acid spray, and. spray means operable to provide .a spray of etching fluid which is directed 1 onto the surface of said cylinder between said sealing members.

CHARLES L. HENDERSON. CHES'I'ER R. POWERS.

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