US2121309A - Rotary printing press - Google Patents

Description

J 21, 1938. a. WALE ROTARY PRINTING PRESS Filed March 28, 1955 2 Sheets-Sheet 1 INVENTAOR Z2 Arfoz rsm B. WALE ROTARY PRINTING PRESS June 21, 1938. I

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Patented June 21, 1938 PATENT OFFICE aoramr ramrmo PRESS Bruce. Wale, San Francisco, Calii'., assignor to Standard Process Corporation, Chicago, 11]., a corporation of Delaware Application March 28, 1935, Serial No. 13,461 7 Claims. (Cl. 101-378) This .invention relates to rotary printing presses of that class which print direct to paper from the raised portion of type or its equivalent or from a printing plate whose printing surface is in relief. Such presses are usually known as typographic presses and the printing plates are frequently referred to as' typographic printing plates.

Heretofore, the printing plates as employed in these presses have been quite thick and rigid (the thickness varying from to $4,), being preformed to a definite and predetermined shape to fit the printing cylinders and capable of maintaining such shape by their own strength or self-supporting character. As thus made, the plates are secured to the cylinders merely by clamping them down. The different kinds of plates and the different ways they are produced are too well known to merit detailed discussion, although the most common are stereotypes and electrotypes. l

The use of such thick and rigid printing plates is costly, troublesome and time consuming, not only from the standpoint offorming the original plates, but also because of certain refinements which must be observed in finishing .the plates before they can be applied to the cylinders or printed from. Thus, the plates (owing to the process followed in reproducing the original type form) invariably present uneven or non-concentric printing surfaces, and it is necessary to correct these irregularities, as by underlaying the plates where low spots occur, and shaving down the plates where high spots occur. And, in some instances, as for solid areas, an additional underlay of .010" more or less is required to secure satisfactory inking and impression of that particular solid area.

Notwithstanding these and other. manipula tions, (sometimes referred to as make ready), it is practically impossible to produce a true and accurate printing surface, and hence the adjustment of the inking rollers and of the impression cylinder must be such as to compensate for any irregularities remaining in the curved printing plate. For example, the inking rollers are usually adjusted to have a streak or more in order to reach all parts of the printing surface, and the impression cylinder must likewise be adjusted for a rather heavy squeeze in order to force the paper into contact with the low as well as the high spots of the printing surface. Both of these conditions demand that the depth of relief must be considerable depending upon the character and related locations of the printing areas,

in order to prevent the non-printing areas from being inked or impressed. On a single plate this depth of relief will range between ,6 and 952" in varying amounts.

A still further difliculty arises in feeding the 5 paper through the press. Due to the great depth of relief and the lack of trueness or concentricity of the printing surface of the plate, it is necessary to keep the paper under positive control during the entire period of impression. On such 10 presses this is accomplished by paper tension and pulling rollers acting before and after printing and involving in addition, a considerable arc of wrap" of the paper around the impression cylinder. On sheet-fed presses. grippers are employed to hold and pull the sheet until printing has been entirely accomplished. Because of this necessity, the true and natural flat surface of the paper is distorted, and the paper is obliged to accept the imprint while its fibers and sur- 20 face are in a strained and curved condition. This, incidentally, adds to the necessity of a heavy squeezeto secure satisfactory printing.

While this old practice of printing in typographic presses has prevailed for many years and 25 in fact is in common use today, being perforce accepted as satisfactory for good printing, the objections referred to are inherent in the practice and the perfection acquired in printing is dependent essentially upon the skill and care 30 exercised in preparing the printing plates and in the make ready.

The present invention is intended to obviate or minimize the foregoing objections in typographic presses and contemplates a novel form of print- 35 fng plate which can be applied directly to its supporting cylinder and used at once for printing without the necessity of any further manipula-,- tion and without the need for any particular skill. It is also within the contemplation of the 40 invention to provide a printing plate which may be produced at small cost and without difliculty and still be capable of printing with the utmost accuracy.

In the practice of my invention (speaking of a 45 preferred embodiment), I employ a flat zinc or copper plate of an initial uniform thickness of the order of .006" to .008"; I make from it a zinc or copper etching, and in the etching step I remove the metal to a depth of .002 to .004". 5 This method (etching) of producing a plate gives a uniform depth of relief in the entire extent of the plate, hence the non-printing surface will be at a uniform and constant distance, below the printing surface on any given plate, regardless of subject. I am careful so to control the etching step that the plate will not be eaten through where flaws appear in the metal but I have found that even if, in consequence of accident or inattention. the plate be eaten through in such places, the desired result may still be gained. Considering these dimensions, it is readily apparent that so thin a sheet of metal is in fact shapeless. The etched plate is then applied directly to a truly cylindrical supporting member or carrier by means mounted on the carrier and which are operative to draw the plate taut about the face of the carrier with suflicient tension to bend the plate to and maintain it in true cylindrical shape for printing, the carrier with the plate as thus mounted'thereon becoming of course the printing cylinder. Nothing further is required, and the printing operation may be carried on as usual.

In my commercial development, I have printed letterheads and billheads from such plates when mounted on printing cylinders 11" in circumference and even as little as 8.50" in circumference, this latter circumference corresponding to a diameter of 2.70". I mention the type of printing and the small size of the printing cylinder to emphasize the radical change brought into the art by my invention, it being obvious that the printing of letterheads and billheads (which usually present an extensive blank or white area), as well as the small size of printing roller, aggravate the conditions which must be met to produce good printing. Nevertheless, the printing produced under the conditions stated was substantially perfect and presented no particular difllculty.

It will be seen, therefore, that my novel printing plate, while having its printing portions of substantially greater thickness than that of its non-printing portions, relatively speaking, is so thin and flexible in its thicker printing portions, yet possesses such tensile strength in its thinner non-printing portions, that the plate, when applied under tension to a truly cylindrical supporting member, will present a true cylindrical printing surface. According to the dimensions given above, the depth of etching does not exceed onehalf the original thickness of the plate (being in fact just one-half in the case of the .008" plate), it being found that under such conditions the stresses set up in the thicker printing portions are no greater than those setup in the thinner non-printing portions and that as a consequence the plate when applied under tension to its sup-- porting cylinder will be given a true cylindrical shape, its smooth back conforming exactly to the smooth rigid surfaceof the cylinder, its printing face being drawn into corresponding cylindrical shape, and the non-printing surface being likewise given true cylindrical shape so as not to destroy the uniform depth of relief.

In the use of my improved plate, as thus mounted on its supporting cylinder, the inking roller is set in non-contacting relation to the plate, being spaced from its printing surface at a distance corresponding to the desired thickness of the ink film to be deposited thereon, and the impression cylinder is also set in non-contacting relation to the plate, being spaced from its printing surface at a distance slightly less than the thickness of the material to be printed upon. Owing to the shallow depth of relief of the printing plate, the printing and impression cylinders are enabled to advance the material through the pass formed by and between them solely by their contact therewtih and this irrespective of the nature or extent of the printing surface, it being remembered that the plate is of such thinness and flexibility as to become a perfect cylinder when mounted under tension on a truly cylindrical supporting member.

The invention is particularly suited for commercial work, such as letterheads, billheads, ruled forms, and other printed matter commonly ordered in large quantities. For such work, a small printing press embodying my improvements will answer the needs of a job-printing establishment which is required to turn out such work with speed and economy. Because of their extreme thinness and flexibility, the plates when removed from the supporting cylinder may be laid out fiat and stored away in that condition, thereby contributing to further economies in storage or filing, etc.

While as just stated the invention is particularly suited for letterhead and similar commercial work requiring the use of a small printing cylinder, it should be understood that the invention in its broader phases embraces the complete scope of the typographic printing art in which relief surfaces are used for printing direct to paper. It is also worthy of note that the invention, in the production of the improved plate, permits the use of the customary etching process which eliminates all possibility of perpetuating any irregularities or unevenness in the original typographic surface to be reproduced. In fact, the invention provides for the first time an etched relief plate capable of being mounted directly on the printing cylinder of a rotary press. In the usual production of zinc etchings, a plate of a thickness of or more, is employed. The etching step involves the removal of the metal to a depth of the order of .05. Additionally, over broader spaces between the lines of the etching, the metal is routed out to greater depth. This is done in order to prevent the surface of the plate in these cut-away portions from coming into contact with the inking rollers or with the paper. The plate when prepared is mounted on a plane-surfaced wooden block. It is rigid, and, in the printing, surface-to-surface contact under pressure is made between paper and plate. It is obvious that such a plate is incapable of being used directly on the printing cylinder of a rotary press, first, because the thickness of the printing portions of the plate is too great to permit them to be given a true cylindrical shape by applying the plate under tension to the printing cylinder, and second, because the thickness of the non-printing portions is so small in relation to the original thickness of the plate that said non-printing portions would not possess sufficient tensile strength to bend the thicker printing portions into true cylindrical shape when the plate is applied under tension to a cylindrical supporting surface. Moreover, the depth of relief of the printing surface of such a plate is altogether too great to enable the printing and impression cylinders to advance the material through them solely by contact therewith. Indeed, the depth of relief is so great that the use of tractive devices would be required to advance the material through the .pass formed by the printing and impression cylinders in order to nullify or render ineffective any tendency of the cylinders to advance the material, such being the condition which actually prevails in typographic presses employing stereotypes or electrotypes.

2,121,509 I c c with the'paper, it being noted from Fig. 1 that In the accompanying drawing: i Fig. 1 is a, sectional view, largely diagrammatic, of a typographic press embodying my inventlon;

Fig. 2 is a plan view of the improved printing plate, broken away at the center; I

Fig. 3is alongitudinal section on an enlarged scale taken through the printing plate of Fig. 2;

Fig. 4 is an enlarged cross section taken through a portion of the printing cylinder and showing one form of the tensioning means employed for applying the plate to the cylinder;

Fig. 5 is a view similar to Fig. 4, but showing another form of plate tensioning means;

Fig. 6 is a section taken longitudinally through the tensioning means of Fig. 5;

Fig. 7 is an. enlarged cross section taken through a portion of the impression cylinder and showing the tensioning means employed for applying the tympan paper to the cylinder;

Fig. 8 is a plan view of a printing plate used for tabular work, the plate being broken away both longitudinally and transversely; and

Fig. 9 is a perspective view of a section of the plate shown in Fig. 8.

Referring to Figs. 2 and 3, a plate I, of the; initially small thickness already indicated, is subjected to the usual operations of making a zinc etching, with the qualification, however, that the etchingstep is shortened. Ordinarily the metal will be eaten away to a depth not greater than .004. In addition to the characters 2, the margins 3 at the ends of the plate are protected and left of undiminished thickness. Across these end portions, however, properly spaced lines 4 are etched. In these end portions,

too, are formed orifices 5. When the plate has been prepared in the flat, the margins are ,bent along the lines 4, to form the terminal channels 6 and I.

The printing roller or cylinder 8, ordinarily of steel, of a size to which the plate is accurately formed, is provided with a longitudinally-extending groove 9. The plate is applied to the roller with its marginal channels 6 and 1 nested one within the other, andthe nested channels within the groove 9. A clamping bar I is then set within the inner channel and the whole is secured by screws II that penetrate the bar l0, pass throughthe orifices in the plate, and enter screw-holes in the body of the roller. All is accurately proportioned, so that the plate is drawn taut upon the face of the roller and firmly secured. The securing means are such that plates are readily applicable to and removable from the roller, and a minimum space, circumferentially, is required for anchorage. It follows that for a given area of printing surface the size of the roller may be reduced to a minimum;

and this, as I have indicated, is advantageous.

Referring to Fig. 1 the roller 8 with a plate secured upon its surface is brought into usual association in the printing press. Cooperating with it is an impression roller or cylinder l2, which is a smooth. steel roll of like diameter faced with a tympan sheet iii of paper (or it might be a thin layer of semi-hard rubber);

and between these two rollers the paper P to be printed is advanced. Ordinarily the rollers or cylinders 8 and I2'are positively driven at equal surface speeds, and the paper is caused to advance at uniform speed with them as they rotate.

- In the present instance, such advance of the paper is effected solely by the mutual cooperation of the two cylinders or by their contact the cylinders are setin non-contacting relation, withthe surface of the impression roller spaced from the printing surface of the printing roller at a distance slightly less than the thickness of the paper. The printing areas and the nonprintlng areas alike (regardless of the irregularity or unevenness of the form or pattern) advance the paper. In extreme cases, the printing plate I may be formed in relief with marginal bands 2, constituting no part of the printing image, to aid the printing and impression cylinders in affecting the advance of the paper.

The paper may consist of detached sheets, one entering the roll-pass with each rotation ofthe printing roller 8 or, as commonly will be the case, the paper may consist of a continuous web.

'Upon the continuous web a sequence of impressions will with the successive rotations of the printing roller be printed; and, if the paper he a. continuous web, rotary shears may be driven in synchronism with the press, to cut the printed web to a succession of accurately measured pieces. I

In my copending application Serial No. 726,875, filed May 22, 1934, I have disclosed special devices for feeding paper to the press in both sheet form and in web form and these devices will be found to be particularly useful in a press equipped with my improved printing plate.

Associated with the printing roller or cylinder 8 are suitable inking means, including in this case the inking roller l5. This roller, as will be noted from Fig. 1, is set in non-contacting relation to the printing'surface of plate I, being spaced therefrom at a distance corresponding to the desired thickness of the ink film I5 to be deposited upon the printing surface. As the inking roller is thus arranged, no ink, will be deposited upon the non-printing surfaces of the plate I and there will be no smudging of the paper during the printing impression even though the paper at times will touch such nonprinting surfaces as it is advanced by the contact therewith of the printing and impression cylinders.

Figs. 5 and 6 show a modified form of tensioning means for applying the printing plate, here designated I, to the printing cylinder, 8. In this instance, the terminal unetched portions 6 and 1 of the plate do not nest one within the other, as in Fig. 4, but are clamped in end to end relation between two bars 20 and 2| by means of short screws 22 passing through plain openings formed in theouter bar 20 and screwed into threaded openings formed in the inner bar 2|, the plate l being formed with. notches in its opposed ends to straddle the screws. Once ,the plate is clamped between-the two bars 20 and 2| they arethen drawn downwardly or inwardly in the parallel sided groove 9 by long screws 23 which pass through plain openings formed in both bars and are screwed into threaded openings 24 formed in the bottom wall of the, groove 9. In applying theprinting plate to the printing roller therefore, according to this embodiment, it is merely necessary first to clamp the ends of the plate between the bars 20 and 2| in the manner just described and then to draw the two bars as a unit down into the groove 9 by turning the screws 23, this being done progressively and uniformly until'the necessary tension is applied to the plate to shape it upon the the supporting surface of the printing cylinder. It will be observed that the bar 20 in Order the plate will not be relaxed.

of the bar 20 and the sides of the groove 9 to accommodate the thick terminal portions of the plate, although the space provided isintended to make a tight fit between the contacting surfaces that the tension originally applied to Fig. 7 shows a convenient method of applying the tympan paper IE to the impression cylinder l2. Here it will be observed that the ends of the tympan sheet are folded over reinforcing wires 11 to produce what in effect are two beaded edges.. These beaded edges are then placed in longitudinal grooves formed in the side walls of a clamping bar I8, which latter is adapted to be drawn downwardly by screws 19 into a parallel 'sided groove I 8' formed in the impression cylinder in a zone corresponding to that occupied by the groove 9 in the printing cylinder 8. In using a thin printing plate, such as herein described, one thickness of tympan paper will ordinarily sufllce, although care should be taken to see to it that the paper is always drawn taut upon the surface of the cylinder.

In Figs. 8 and 9, there is shown a printing plate I which gives a better illustration of the kind of plate that would be used for commercial work, the plate shown being a typical example of one intended for printing tabular work involving the use of type matter as well as rule matter. In this example, it will be noted that practically the whole area of the plate is occupied by the printing image, although the spacing of the different parts of the image is irregular and nonuniform except for the horizontal lines which are more'or less uniformly spaced in this particular example. In the use of a plate such as I, there would never be need for the use of separate marginal bands such as bands 2 shown in Fig. 2. It will have been understood that the printing plate I shown in Figs. 1 to 4 is intended primarily for purposes of illustration, although it could actually be used in the form shown. l

The subject of the zinc etching may be what one will; and it may, as will be understood, be applied to the plate photographically, by contact printing or otherwise, from a'master-piece that may itself be a print or drawing. or from an original of other form or character.

The term zinc etching is one that has come to be applied by extension to an etched metal place, even though the metal be other than zinc. I shall in the ensuing claims use the terms etching and metal to cover such wider field.

My improved plate, when compared with prior printing plates used intypographic presses, presents striking and numerous dissimilarities:

Prior plates'are thick and rigid, being applied to the printing cylinder after being preformed to shape (stereotypes are of course cast, while electro types are'rolled or pressed to shape, usually when heated) and capable when removed from the cylinder of maintaining their shape by their own strength, and self-supporting character; whereas my plate is thin and flexible, being made from sheet metal by an etching process and shaped directly on the cylinder, audit is incapable when removed from the cylinder of maintaining printing shape or any definite shape.

Prior plates are secured to the printing cylinder by clamps which act merely to hold the plates down in place; whereas my plate is secured to the cylinder by drawing means thereon which exert sufficient tension on the plate to give it its proper printing shape,the plate in fact being incapable of being brought to printing shape except when thus applied to the cylinder.

Prior plates, because of their thickness and method of production, invariably present untrue or non-concentric printing surfaces; whereas my plate, because of its thinness and method of production, always presents a true cylindrical printing surface.

Prior plates, also because of the untrueness, of their printing surfaces, require a great depth of relief, as well as a non-uniform depth of relief; whereas my plate, because of the trueness of its printing surface, permits of a small depth of relief, as well as of a uniform depth of relief.

Prior plates, because of their great and nonuniform depth of relief, present non-printing portionsnot nearly so thick as the printing portions, thereby forbidding the use of tension in attaching the plates to the printing cylinder; whereas my plate, because of its small and uniform depth of relief, presents non-printing portions which can be made half as thick as the printing portions, this relative thickness of the printing and non-printing portions permitting the plate to be shaped under tension on the printing cylinder and in fact forbidding shaping in any other manner.

Prior plates, because of the lack of trueness or concentricity of their raised printing surfaces, require the use of inking rollers and impression cylinders which are set to rotate in overlapping relation to the printing cylinder so as thereby 'to make a substantial or wide surface contact with the printing surfaces, these conditions necessitating a great depth .of relief of the printing surfaces; whereas my plate, because of the trueness or concentricity of its raised printing surface, permits the use of an inking roller and of an impression cylinder which are set in noncontacting relation to the printing cylinder or the printing surface of the plate, these conditions permitting a minimum depth of relief of the printing surface.

Prior plates, because of the lack of trueness or concentricity of their raised printing surfaces, as well as the great depth of relief of these surfaces, necessitate the use of tractive devices for advancing the paper through the pass formed by and between the printing and impression cylinders; whereas my plate, because of the trueness and concentricity of its printing surface, as well as the small depth of relief of this surface, enables the printing and impression cylinders by their own tractive effort to advance the paper through the pass formed by and between them. a

Prior plates are costly, requiring special treatment or make ready after casting or shaping; whereas my plate is relatively inexpensive, requiring no special treatment or make ready after the etching operation.

Prior plates cannot be conveniently stored away for repeated use because of their bulk and their permanently curved form; whereas my plate, because of its light flimsy character, can be used repeatedly and laid out flat for filing away in any standard filing cabinet like an ordinary paper record.

Prior plates are not well suited for letterhead and similar commercial work, being altogether direct to paper.

too costly; whereas myi plate is particularly adapted for such work.

It will be seen therefore that my invention represents a decided innovation in typographic printing presses. The improved plate is really unique and offers an entirely new technique in the art of typographical printing surfaces.

I am aware that printing plates which may be said to be thin and flexible have been 'used in planographic or offset presses as well as in intaglio presses, and that in some instances it has been proposed to apply these plates to their supporting cylinders by means of tension. Such planographic or intaglio printing plates are not intended, designed or adapted for use in a typographic press and hence they afford no basis of comparison with my improved plate which,

as already pointed out, has been evolved to meet the special and peculiar conditions arising in a typographic press. A typographic printing plate must present a relief printing surface which can be inked by a roller and which can print My improved plate, being a typographic printing plate, does (as it must) meet these requirements, and it has been seen from the detailed comparison above, how radically my improved plate differs from prior plates in the same class. The idea in applying planographic and intaglioplates by tension to their supporting cylinders is much the same as that followed in applying tympan sheets to impression cylinders and rubber blankets to offset cylinders, the object in all cases being to facilitate the .application and removal of the cylinder facings for renewal or substitution purposes. While my improved plate possesses that advantage also, it is purely secondary, the thinness and flexibility of the 'plate and its other structural characteristics being determined solely from the standpoint of printing and press operation.

I have herein shown and described my invention merely in preferred form and by way of example, and it will be understood that many changes and variations may be made in the form,

arrangement and dimensions of the parts without departing from the spirit of the invention. It should be understood, therefore, that I do not limit myself to any particular form, arrange ment or dimensions of the parts except insofar as such limitations are specified in the appended claims.

This application is in part a renewal and continuation of an application filed by me April 20, 1933, Serial No. 666,987, allowed April 11, 1934, and in part a continuation of my before-mentioned copending application Serial No. 726,875, filed May 22, 1934.

, Having thus described my invention, what I claim is:

1. A printing element adapted to print directly upon sheet material irrespective of the nature of the subject matter to be printed and irrespective of the relation in area or location of the printing portions to the non-printing portions comprising a rigid carrier having a smooth curved surface and a thin flexible sheet metal relief printing plate drawn taut upon the surface of said carrier by means of uniform tension applied to said plate, said plate having an outer face comprising printing and non-printing-portions, the latter having a uniform depth of relief with respect to said printing portions, the

render the plate freely flexible in the thicker or printing portions while at the same timermaintaining high tensile strength .in the thinner or non-printing portions and said tension being suflicient to shape both-printing and non-printing portions of said plate to conform'accurately to' the curvature of said carrier surface.

2. A printing element of the-type defined in claim 1 wherein said printing plate is etched to obtain said uniform depth of relief of the nonprinting portions at said outerface.

3. An element according to claim 1 wherein said plate is formed to provide a relief of sumcient height to print on paper passed between said impression means and said plate, yet sufliciently shallow to cooperate with the non-printing portions of said plate to produce a definite advance of the paper to be printed upon irrespective of the nature or extent of the printing image. f

4. An element according to claim 1 together with means provided within said element to draw said plate taut uponsaid carrier to secure the desired tension.

5. A printing element adapted to print directly upon sheet material irrespective of the nature of the subject matter to be printed and irrespective of the relation in area or location of the printing portions to the non-printing portions comprising a rigid carrier having an accurate cylindrical surface and a thin flexible sheet metal relief printing plate drawn taut upon the surface of said carrier by means of uniform tension applied to said plate, said plate having an outer face comprising printing and nonprinting portions, the latter having a uniform depth of relief with respect to said printing portions, the relative thicknesses of said printing and non-printing portions being so proportioned as to render the plate freely flexible in the thicker or printing portions while at the same time maintaining high tensile strength in the thinner or non-printing portions and said tension being sufficient to shape both printing and non-printing portions of saidplate to conform accurately to the curvature of said carrier surface without lateral distortion of the design at said printing surface due to said tension.

6. A printing element for a printing press consisting of a cylindrical carrier provided with a longitudinal groove, a plate of metal etched away and bearing over an intermediate portion printing characters in relief, and with marginal end portions etched away along lines of bending, and bent along such lines to channeled shape, the said plate being shaped upon the face of the carrier, its channel-shaped margins nested one within another and both nested within the groove of the carrier, and means engaging the nested channel-shaped margins of the plate and securing the plate to the carrier.

7. The method herein described of preparing the printing element of a printing press which consists in forming by 'etching'upon a medial portion of the surface of a plane sheet of metal a printing character in relief, and upon marginal and portions lines of bending of diminished thickness, bending the marginal end portions of the sheet to channel shape, shaping the sheet upon a longitudinally grooved cylindrical carrier with the channeled margins of the sheet nested together and nested withinthe channel of the carrier. and securing theplate upon the carrier in the so nested-together portions thereof.

. BRUCE WALE.

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