US2305852A - Stereotype printing plate - Google Patents

Description

H. N. DURHAM YsTERlilo'rYPE PRINTING PLATE Dec. 22, 1942.

2 sheets-sheet' 1 Filed Nov. 29, 1939 MTNVETOR. BY Ww Y- ATTORNEYS r Dec. 22, 1942. H, N. DURHAM STEREOTYPE PRINTING PLATE Filed Nov- 29, 1939 2 Sheets-Sheet 2 Patented Dec. 22, 1942 STERETYPE PRINTING PLATE Hobart N. Durham, Manhasset, N. Y., assignor to The Goss Printing Press Company, Chicago, Ill., a. corporation of Illinois Application November 29, 1939, Serial No. 306,598

3 Claims.

IZlhe present invention relates to printing presses and more particularly to new and useful improvements in the stereotype printing plates particularly adapted for use on high speed rotary printing presses.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and `combinations pointed out inthe appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

Of the drawings: Figure 1 is a top plan view of a typical and illustrative embodiment of the plate strengthenv ing member used in connection with the present Figure 4 is a cross sectional view showing a printing plate according to the present invention clamped to a printing cylinder and ready vfor operation on the press; and

Figure 5 is a side elevation of the printing cylinder shown in Figure 4 but with the plate removed.

The present invention has for its object the provision of a novel and improved printing plate particularly adapted for use on a rotary printing cylinder which is to be operated at relatively high speeds of rotation. Another object of the invention is the provision of a relatively light yet exceedingly strong stereotype printing plate adapted for use on rotary printing presses and which will run without danger of breaking for unusually long periods of time. The invention also provides a novel and extremely strong printing plate which has a reinforcing member which may be used over and over again.

In accordance with the illustrative embodiment of the present invention, the printing plate comprises a relatively thin partially cylindrical stereotype cast from metal of relatively low melting point and relatively low tensile strength such convex side comprising the text and illustrations or whatever other matter is to be reproduced, and having its concave surface generally smooth so that the concave and convex surfaces are concentric. Within this parti-cylindrical plate, and extending for substantially its full width and from one straight edge to the other straight edge, is a. thin flexible perforate sheet of relatively high tensile strength having a melting point substantially above that of the stereotype metal, and for this purpose this perforate sheet may well be made of stainless steel. Along each straight edge of the plate, the inner flexible reinforcing sheet extends beyond the edges of the plate and is shaped so that it may be easily gripped by suitable clamps or other devices on the printing cylinder. The perforations in the reinforcing sheet are preferably elongated circumferentially of the plate so that the danger of the inner and outer layers of the plate being sheared from each other during the printing operation is substantially eliminated.

Heretofore stereotype plate for use on rotary printing presses have been extremely heavy, and it is only recently that semi-cylindrical plates such as are usedfor newspaper work have been substantially reduced in weight although they are still generally of relatively heavy weight. When such plates are operated at relatively high speeds of rotation such as four or ve hundred revolutions per minute for extended periods of time, the plates show excessive wear and occasionally become sufficiently brittle and crystalline thatfracture of the plate occurs, causing damage to the press and possible injury to the Workman. These effectsv are largely due to the fact that the centrifugal force developed by the heavy semi-cylindrical printing plates are greater than can be adequately resisted by the platesecuring means commonly used, and the present invention avoids these defects by reducing the mass of the plate, increasing its tensile strength and providing cooperating means on the plate and cylinder by which the plate may be more securely held during the high speed operation of the press.

It will be understood that the foregoing general description and the following detailed description as well, are exemplary and explanatory of the invention but are not restrictive thereof.

Referring now in detail to the illustrative embodiment of the invention as shown in the accompanying drawings where Figures 1 and 2 show a. typical and illustrative form of reinforcas stereotype metal, having a printing face on its ing member on which the strereotype plate is to sheet of stainless steel or other material having a relatively high melting point and relatively high tensile strength, and this sheet I is formed with a relatively large number of elongated slots II which are preferably arranged' in rows and are uniformly spaced, the slots in one row being staggered with reference to the slots in adjacent rows. The slots are preferably elongated circumferentially of the cylinder, and as illustratively shown are several times as long as they are wide. and extend from one straight edge of the plate to the other straight edge and from a point closely adjacent to one curved edge of the plate to a point closely adjacent to the other curved edge.

The ends of the sheet I0 are preferably rolled around a rigid bar I2 and are lapped as at I3 where they may be secured by welding so as to provide an enlarged edge of even greater strength at the two ends of the plate by which the reinforcing member may be gripped during casting and during the printing operation.

Means are provided for tightly stretching the reinforcing sheet I0 to a semi-cylindrical shape during the casting operation, and for holding it at a relatively uniform distance between the adjacent faces of the core and cope, and preferably the reinforcing sheet is held so that it is centrally disposed with respect to the casting chamber.

These stretching and spacing means comprise a plurality of interrupted narrow ribs 35 'which are formed in circumferentially extending rows on the convex surface of the'cylindrical core 2l, the ribs of one row being staggered with respect to the ribs of adjacent rows, and the several rows being so positioned that when the reinforcing sheet I0 is in casting position its slots II do not overlie the ribs 35. 'The ribs are preferably long and narrow and come to a relatively sharp edge so that the indentations caused by them in the plate do not leave any large 'area of the nished plate'without substantial support, and near the straight edges of the plate, the ends of the individual ribs 35 are preferably so formed that they do not interfere with the drawing of the core from the cast plate, although the resiliency of the plate will permit the plate to be stripped from the core. l

After the reinforcing sheet has been properly positioned in the casting chamber, the molten stereotype metal is poured into the casting chamber and lls the space between the matrix 20 and the convex surface of the core, the metal ilowing in on both sides of the reinforcing sheet I0 and through the slots II, thereby uniting the reinforcing sheet, the inner and outer faces of the plate, and the metal filling the slots II into a single piece forming the semi-cylindrical printing plate.

'Ihe printing cylinder of the present invention with a reinforced stereotype plate secured on its surface is shown in Figures 4 and 5 of the drawings, and as there embodied the cylinder 40 is adapted to receive a plurality of plates and is shown as being one page wide and two pages in circumference. Clamping means for tensioning the plates circumferentially of the cylinder are disposed substantially diametrically opposite each other, the clamping means for the adjacent ends of two plates being provided in the marginal space between the plates. Between the clamping means, the surface of the cylinder is preferably smooth. but at each end of each plate the 2,305,852 y l be cast: This reinforcing member comprises a :"'cylinderv is providedwithgrooves 4I which are v adapted to receive the reinforced ends I2 of the reinforcing sheet I0, and these grooves are preterably so positioned that as the ends I 2 are'drawn radially inwardly into the grooves, an increasing tension is applied to the reinforcing sheet II so as to securely hold the sheet and plate against the surface of the cylinder.

'Cooperating with the grooves 4I are a plurality of fingers 42 having their inwardly extending portions 43 threaded and passing through the threaded interior of the' respective worm gears 44, these worm gears being seated within the axially extending slots 45 and adapted to be turned in unison by means of the worms 4l on worm shaft 41 which extends beyond one end of the cylinder and is connected to the squared member 48 which receives the hand crank for rotating the shaft 41 and moving the clamps 42, 43 inwardly and outwardly. A separate worm shaft is provided for each set of clamps, and the two sets of clamps for the adjacent ends of the two semi-cylindrical plates are preferably staggered so that they may be actuated by separate worm shafts 41. The finger-like ends 42 of the clamps are of relatively small height so that they do not extend beyond the surface of the plate, and are sufllciently low so as notto engage the inking rollers during the` printing operation.

Whatever stretch there is in the plate at the beginning of the printing operation, is fully taken up by the action of the clamps 42, 43, and if'the plate has any tendency to stretch during the printing operation, as for instance after an exceedingly long high speed run, the plate can be,

additionally stretched by further turning of the worm shafts 41. 'I'he tendency of the plate to trifugal force, and the external face of the plate may elongate more than the inner face of the plate due to the rolling action during printing. However, this causes no damage to the plate as the elongated slots II provide a relatively long and narrow connection between the inner and outer cast portions of the plate so that any shearing actionv between the inner and outer layers does not cause an appreciable weakening of these connectingmembers within the slots II.

After the printing operation has been completed, the discarded plates may be thrown in the melting pot of the stereotype casting equipment and the stereotype metal is melted there'- from. -However, if the reinforcing sheets are made of steel or some similar materiaL'they rise to the surface of the melting pot as soon as the stereotype metal has been melted therefrom, andthey may then be recovered from the melting pot for use over and over again. Stainless steel is the preferred material, due not only to its non-corrosive properties but also tothe fact that it has substantially the same coeii'icient of thermalexpansion as stereotype metal, and less trouble with buckling is experienced by its use.

The invention in its broader aspects is not limited to the specic mechanisms shown and described but departures4 may be-made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

What I'claim is:

1. A curved stereotype printing plate comprising a metal sheet having elongated perforatiom therein, the perforations being elongated circumerentially of the sheet and a stereotype body cast thereon and passing through the perfora-` tions.

2. A curved stereotype printing plate comprising a metal sheet having elongated perforations therein, a curved stereotype body cast on both sides of the sheet and passing through the perforations, the perforations being elongated circumferentially of the plate and reinforcing members attached to opposite straight edges of the sheet and extending beyond the adjacent ends of the stereotype body.

3. A curved stereotype printing plate comprising a perforate sheet of metal having relatively great tensile strength and of approximately the same thermal expansion as the stereotype metal, a stereotype body cast on the metal sheet and extending through the perforations in the sheet, said perforations being 'elongated circumferentially of the curved plate,

HOBART N. DURHAM.

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