US2788743A

US2788743A - Apparatus for photogravure and similar printing

Info

Publication number: US2788743A
Application number: US312372A
Authority: US
Inventors: Andre K Schwerin
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-09-30
Filing date: 1952-09-30
Publication date: 1957-04-16
Anticipated expiration: 1974-04-16

Description

April 16, 1957 w 2,788,743

APPARATUS FOR PHOTOGRAVURE AND SIMILAR PRINTING Filed Sept. 30, 1952 2 Sheets-Sheet 1 Inn-Arron April 16, 1957 sc w Rm 2,788,743

APPARATUS FOR PHQTOGRAVURE AND SIMILAR PRINTING Filed Sept. 30, 1952 2 SheetsSheet 2 2.1a zoig 7 A, Invsuron .SC/IWER/N Hi 5 fl/VDRE Hrromvzrs APPARATUS FOR PHOTGGRAVURE AND SIMILAR PRINTING Andre K. Schwerin, Montreal, Quebec, Canada Application September 30, 1952, Serial No. 312,372

3 Claims. (Cl. 101 382) This invention relates to improvements in method and apparatus for photogravure and similar printing.

According to certain present known methods of photogravure printing, a screened gelatine relief, obtained from photographical layouts or other printable material must be etched or engraved on the surface of a cylinder or roll which has been conditioned for engraving thereon. This necessitates a great deal of time and expense in preparing the surface of the cylinder and the subject matter to be engraved thereon. For example, in the preparation of photographic materials for reproduction on the cylindrical surface, all of this material to be reproduced has to be premounted on a common form. In the case of a plurality of reproduction positives of different density and contrast it is necessary to retouch each of these in order that their densities and contrasts may be equalized for a single engraving process on the surface of the cylinder. The retouching of each individual positive is lengthy process and particularly costly. In any case with this system as above outlined the Whole surface of the cylinder must be engraved in one operation and there is no possibility of removing sections from the engraved surface of the cylinder.

A particular advantage of the present invention is that the positives employed for reproduction may be individually exposed and the gravure may be done on separate, flat and flexible plates without regard to the density or contrast of the positives. The engraved plates which are of a special alloy which is sensitive to magnetic attraction, are then mounted on a cylinder having a magnetized surface designed to cause the plates to adhere thereto. This facilitates the assembling of the engraved plates about the cylinder and thereby dispense with the cumbersome process of engraving the entire surface of the cylinder.

The present invention also permits of quick interchangeability of all engraved sheets both before and during the printing process, particularly where it is desirable to re-arrange their location in the master plan or to substitute new material. It frequently happens in the news printing industry that important pictorial items of news come in just before, and in some cases during,

the printing operation. When these items are of sufficient importance, substitution must be made which necessitates scrapping the engraved cylinder or roll on hand and engraving a new cylinder with the substitute engravings incorporated therein. Otherwise, the paper must go to press without the latest news pictures. According to the present invention any number of engraved plates can be removed, re-arranged and substituted by others at relatively small cost both as to labour and materials.

Another advantage is that a faulty engraving does not result in the loss of a cylinder as in the case of the entirely engraved cylinder. A faulty engraved plate can be removed from the cylinder of the present invention without affecting the remainder of the plates thereabout.

nited States Patent Patented Apr. 16, 1957 Still another advantage is that the plates after having been used can be stored for future use in an entirely new set-up. This is not possible with the entirely engraved cylinder.

The above and other features and advantages characteristic of this invention will be understood more readily from the following detailed description taken in connection with the accompanying drawings, in which- Fig. 1 is a perspective view illustrating a printing cylinder embodying my invention.

Fig. 2 is a sectional view taken along the lines 2-2 of Fig. 1.

Fig. 3 is a perspective view of one segment of the magnets of a cylinder, illustrating the manner of assembly of the elements of a magnet, the cylinder having been removed for sake of clarity.

Fig. 4 is a sectional view enlarged, taken along the lines 44 of Fig. 1.

Fig. 5 is a view similar to Fig. l, but showing the backing sheet only partially surrounding the cylinder.

Fig. 6 is a sectional view of the cylinder taken at rightangles to the view shown in Fig. 2.

Fig. 7 is an enlarged detail of a fragment of the cylinder shown in Fig. 2.

Fig. 8 is an elevational view showing details of the cylinder with the backing sheet and plates removed.

Fig. 9 is an enlarged perspective view of a fragment of the cylinder shell, assembly parts having been removed for sake of clarity.

Referring more particularly to the drawings, 5 generally indicates a printing cylinder in association with a press roll 6 of a photogravure type printing machine. The printing cylinder is provided with a magnetized surface about which a thin backing sheet 7 is secured with the adjacent surface of said sheet to the entire surface of the cylinder by magnetic attraction. The sheet 7 is provided with a plurality of apertures 8 for the insertion of engraved sheets or plates 9 of a thickness equal to the thickness of backing sheet 7. Plates 9 are of a steel alloy of high magnetic permeability to ensure magnetic attraction of the plates to the magnetized surface of the cylinder 5. The exposed surface of plates 9 has a thin copper film obtained by electrolysis, or other suitable application, for engraving purposes. When plates 9 are magnetically secured to the surface of cylinder 5 within the apertures 8 of sheet 7, a thermoplastic filler It is inserted between the edges of the plates 9 and the opposing edges of the backing sheet 7 which define the apertures 8 so as to completely fill the spaces and to provide a homogeneous cylindrical surface presenting no obstacle to the blade of a printing machine. The thermoplastic filler 10, when set, also serves as a bonding agent to prevent sliding movement of plates 9 relative to the backing sheet 7.

The main purpose of the apertured backing sheet 7 is to provide a rapid means of locating the engraved plates according to a master plan. Thus when it is desired to reproduce color or black and white photographs on certain pages, for example of the rotogravure section of a newspaper, the text will be arranged according to a predetermined plan and blank spaces will be provided for the reproduction of a photograph thereon. The backing sheet will then be apertured to receive a photo reproduction plate so that the reproduction of the photographs will coincide with the allotted space on the sheet to be printed. The surface of the backing sheet 7 may '15 in communication with

grooves

16 or 17.

7 core 2'7.

3 provide locations for the separate engraved plates 9 according to a master plan. However, the backing sheet may be dispensed with when not required and the plates alone can be arranged over the surface of cylinder 5. The plates 9 will be secured to the surface of the cylinder by magneticattraction and the spaces between each plate filled with a thermoplastic filler 3rd to provides; homogeneous printing surface and to prevent any shifting of the plates relative to one another on the surface of the cylinder during the press operation.

Cylinders comprises -a shell of brass or other suitabienon-magnetic material (see particularly Fig. 9).

The surface of shell 15 is recessed to provide circuml5 and 19 extending from the grooves l6 and 17 respectively. I Grooves 18 and 19 are alternately arranged and have their ends remote from their connecting circumferential groove terminating. short of the opposing circumferential groove. Openings 20 extend through shell The in terior of shell l5-is provided with brass discs 21 spaced inwardly from opposite ends and secured in place by screws 21a extending through shell 15. Discs 2 1 are provided with a. central opening through which the axis shaft 22 fitted in a sleeve 23 extends. Sleeve 23 is of brass or other non-magnetic material. The web portion 24 of discs 21 is provided with suitable openings 25 through which an electro-magnet extends. The magnet consists of an electrically energized winding 26 about a The positive and

negative terminals

28 and 29 are connected to source of current supply (not shown) through conducting

rings

30 and 31 respectively on sleeve 23 and brushes 32 and 33 connected to positive and

negative leads

34 and 35 from said source of current supply. Core 27 which projects from opposite ends of the winding 26 extends through an opening in non-magnetic plates 36 secured to the outer surface of discs 21 by screws 37 over openings 25. Plates 36 serve to support the magnet.

A grill comprising a curved bar 49 and spaced parallel fingers 41 is embedded in the surface of shell 15 with the curved bar 40 lying in the circumferential groove 16 and the fingers 41 lying in grooves 18. A connecting post 42 extends from the under side of bar 4t], through a communicating opening 20 in the shell and has its free end connected to one pole of core 27 by means of a connecting elbow 43. A second grill comprising a curved bar 44 and parallel fingers 45 is also embedded in the surface of shell 15 with the bar 44 lying in groove 17 and the fingers in grooves 19. A connecting post 46 extends from bar 44, through a communicating opening Zil in the shell and has its free end connected to the opposing pole of core 27 by a connecting elbow 4-7. With this arrangement each finger of one pole extends substantially across the width of the cylinder between adjacent fingers of the opposing pole and in spaced relation thereto. The bars 4% and 44 and

fingers

41 and 45 have their exposed surfaces lying in the circumferential path of the outer surface of shell 15 to provide a homogeneous surface upon which the backing sheet 7 and/or plates 9 are disposed.

in the drawings (see Fig. 2), I have shown four electro-magnets with the grills of each magnet arranged in spaced relation about the circumference of the shell so as to divide the magnetic field into four equal segments. This is shown for illustration purposes only, since the number of magnets and the segment which each magnet covers depends on the circumference of the shell and the capacity of each magnet. For example, a shell of a smaller diameter may require only two magnets with the grills of each magnet covering a segment equal to one half of the circumference of the shell. Alternatively,

a single magnet may suflice'for an even smaller shell.

thereto by screws 51. Discs 50 are provided with central openings through which the outer sleeve 23 of shaft 22 projects. Complementary slots in sleeve 23 and in the defining walls of the'central opening in discs 5i? are fitted with keys 52 to secure said caps to the sleeve for rotation of the shell with said sleeve. A gear 53 fixed to rotate with sleeve 23 is connected through the medium of gears, indicated at 54, for rotation of cylinder Sin response to rotation of press roll 6.

With reference to Figs. 2, 7 and 8, the backing sheet 7 is fitted about the shell by the insertion of one end 55 through a transverse slot 56 in the shell 15 located intermediate the grills of two adjacent magnets. The terminal portion 57 of the end 55 of sheet 7 is then placed between one'surface of a V-shaped block 58 mounted on the web of a transverse C-shaped bar 59 and a screw clamp es carried by one inturned marginal edge 61 of bar 59. The sheet 7 is then wrapped about the surface of the cylinder and the opposite end 62 is inserted through slot 51: with its terminal portion 63 secured between an opposing inclined surface of block 58 and a second screw clamp 64 carried by the other inturned marginal edge 65 of bar 59. Bar 59 is also provided with outwardly projectin" lugs 65 through which adjusting screws 67 are threadedly arranged. Shoes 68 on one end of screws 67 bear against the inner surface of shell 15 when adjustment of the screws takes place to stretch the backing sheet 7 about the surface of the cylinder.

The adjustment of sheet 7 is accomplished While the magnets are de-energizecl. The plates 9 may also be mounted on the cylinder in the apertures 8 provided there-.

for and the filler It applied prior to energizing the magnets. Once the backing sheet and plates are suitably placed, energization of the magnets ensures that their inner surfaces cling to the adjacent surface of the cylinder to ensure that no distortion will take place on the outer surface of the plates or sheet during the printing operation.

The thermoplastic filler 10 is of a composition which is resistant to water and to aromatic solvents employed in the dilution of rotogravure inks; e. g. polystyrene, a mixture of vinyl ether and casein, or chemical compounds based on polymers of methylsilicone. These types of plastic filler set very rapidly to ensure positioning of the plates on the cylinder surface. They can also be com pletely removed from the cylinder surface by a suitable solvent. The thermoplastic filler is also inserted in the slot 56 after the backing sheet 7 has been secured in place to ensure that the entire printing surface of the cylinder is perfectly smooth.

Having described and illustrated what I now believe to be the preferred embodiment of this invention it will be understood that changes and modifications may be resorted to without departing from the scope and spirit of the present invention as defined in the appended claims. For example, although I have illustrated the use of a single set of magnets within the cylinder for energizing the magnetic grills on the surface of the cylinder, it is also contemplated to employ an auxiliary set of magnets to be employed in the event of an emergency. In this connection it frequently happens that the normal source of current supply breaks down or that the wiring of the magnet or a connection thereto becomes defective. The auxiliary magnets would be connected in such a manner that a defect in the current from the normal source of supply would automatically effect the energization of the auxiliary magnets.

I claim:

1. In an apparatus for photogravure printing, a hollow cylindrical shell of a non-magnetic substance, a magnet mounted within said shell, said shell being recessed in its outer surface to provide a circumferentially extending groove adjacent opposite ends of the shell and to provide two series of parallel transverse grooves between longitudinally extending non-magnetic ribs, one series of said transverse grooves extending from said circumferentially extending grooves adjacent one end and terminating short of said circumferentially extending groove adjacent the opposite end, the other series of transverse grooves ex tending from said second mentioned circumferentially extending groove and terminating short of said first mentioned circumferentially extending grooves, with the grooves of one series alternating with the grooves of the other series, a grill of magnetic sensitive material comprising a curved bar and spaced parallel fingers extending from one side of said bar, said bar being embedded in said first mentioned circumferentially extending groove with its fingers embedded along the series of transverse grooves extending therefrom, a second grill of magnetic sensitive material also comprising a curved bar and spaced parallel fingers extending from one side of said last mentioned bar, said last mentioned bar being embedded in said second mentioned circumferentially ex tending groove with its fingers embedded along the series of transverse grooves extending from said second mentioned circumferentially extending groove, and means connecting said first mentioned grille to one terminal of said magnet and said second mentioned grille to the other terminal of said magnet, characterized in that each of the fingers of one grille serving as a positive pole of the magnet is disposed on the outer surface of said shell between and in spaced parallel relation to adjacent fingers of the other grille serving as negative poles of the magnet which are disposed on the outer surface of the shell to provide a homogeneous magnetic field about the surface of said shell for the attraction of magnetic sensitized printing plates about said shell surface.

2. Apparatus as set forth in claim 1, including a backing sheet of magnetic sensitized material secured about the circumference of said shell within the magnetic field of said shell, said sheet being provided with apertures serving to expose portions of the magnetic field of the shell, a plurality of magnetic sensitized, flexible flat printing plates mounted within selected apertures of said backing plate against the said magnetic field of said shell, said printing plates being contoured and secured to said shell by the force of said magnetic field.

3. Apparatus as set forth in claim 2, in which said printing plates are mounted within said apertures in spaced relation to the defining edges of said apertures, and including a thermoplasti bonding agent applied to said exposed magnetic field between the adjacent edges of the apertures and the plates therein to provide a homogeneous printing surface and to secure said printing plates against sliding movement on said shell relative to said backing sheet.

References Cited in the file of this patent UNITED STATES PATENTS 1,123,055 Wood Dec. 29, 1914 1,258,982 Boedicker Mar. 12, 1918 1,347,101 Jenner July 20, 1920 1,531,492 Marquardt Mar. 31, 1925 1,624,538 Crain Apr. 12, 1927 1,657,287 Trist Jan. 24, 1928 2,056,991 Tomlin Oct. 13, 1936 FOREIGN PATENTS 9511/1914 Great Britain Mar. 25, 1914 159,385 Great Britain Mar. 3, 1921