US1975867A - Printing plate and process of preparing same - Google Patents

Description

Oct. 9, 1934. w. SAUNDERS 1,975,867

lV/LL/AM 5A l/NOERS NNNNNN O R w gm AT ORNEY I Patented Oct. 9, 1934 PRINTING PLATE AND PaooEss or TPREPIARINGQ SAME -Williani Saunders,- Baldwin, N. Y.

Application September'19,1933, sari-amending) r} 1 Claim. (01. 101-4013 1 such service, there is a tendency of the makeready to slip and to get out of register in the operation of the press.

It is the purpose of the present invention to overcome and eliminate the features mentioned and in a sense to incorporate the make-ready in the plate itself.

These objects and others of desirable nature are attained by the novel features of invention in process and structure as hereinafter defined and broadly claimed.

The drawing accompanying and forming part of the specification illustrates the mode of procedure and the strcture embodying the invention and as the same is by way of disclosure rather than limitation, it is to be understood that the process and structure may be modified and changed from such illustration all within the true intent and broad scope of the invention.

Fig. 1 is a face view of an electrotype plate.

Fig. 2 is a cross-sectional View of the same as on line 2--2 of Fig. 1.

Fig. 3 is a face view of the make-ready taken from this plate.

Fig. 4 is a cross-sectional view of this makeready as on line 4i of Fig. 3.

Fig. 5 is a broken cross-sectional View showing the make-ready reversed and applied to the back of the plate in registered relation with the subject on the face of the plate.

Fig. 6 is a broken sectional detail illustrating the operation of impressing the make-ready into the plate in a hydraulic press or the like.

Fig. 7 is a broken sectional detail illustrating the plate with the make-ready raised on the face of the same.

Fig, 8 is a similar detail showing the back of the plate shaved to bring the plate to normal thickness and trimmed ready for use in a printing press.

The electrotype shown in Figs. 1 and 2 may be considered as illustrative of printing plates generally to which the invention is applicable, having the high and low printing and non-printing portions 9 and 10 respectively.

The make-ready shown in Figs. 3 and 4'- also may be considered as typical and produced by known methods from overlay paper or the like and embodying the backing or foundation sheet 11 and the raised overlay surfaces 12.

The invention departs from the usual practice 0. in that instead of using the overlay in cooperation with the face of the plate, it is registered and impressed into the back of the plate to raise the printing surfaces on the face of the plate.

As a first step of this new process, the makeready is reversed and registered on the back of the plate as in Fig. 5, with raised portions 12 of the overlay in register with corresponding printing surfaces 9 on the front of the plate. The make-ready is suitably secured in this registered v relation on the back of the plate, as with a suitable paste or cement and pressure is applied while so registered, to bring up the make-ready on the face of the plate.

The latter operation is illustrated in Fig. 6, where 13 and 14 indicate the companion elements of a hydraulic or other suitable press. A yielding bed for the face of the plate 15 is here shown provided by a layer 16 of lead or like material, which may have a backing 1'7, of newsprint paper or other suitable cushioning medium.

The pressure required varies with the character of the plate. For average purposes, 12,000 lbs. to the square inch may be sufficient. The effect of such pressure is apparent in Figs. 6 and '7, which show how the raised overlay portions on the back cause corresponding areas to be displaced and hence the surfaces of similar outline to be raised or lifted on the face of the plate as indicated at 9'. These raised areas, conforming to the overlay thus have the effect of a makeready incorporated directly in the plate. Hence, no external make-ready is necessary with these new process plates.

The processing described has the effect of increasing the overall thickness of the plate and usually after this raising operation, the back of the plate is shaved as at 18, in Fig. 8, to restore it to original or intended thickness, ready for use on the printing press. This shaving operation may be part of the same process by which the plate is trimmed about the edges, at 19.

By impressing the make-ready into the back of the plate, the printing surfaces are raised in direct correspondence with their values as proved up on the make-ready. Consequently, the plate thus processed gives accurate values in the matters of depth and detail and the make-ready being in effect a permanent part of the plate itself, {19

can not get out of register or lose its effect from the pounding of the press. The invention is applicable to curved as well as to flat plates and is of particular value for fine work, where with prior processes intermediate values have been lost, due to inaccuracies in the make-ready and the like. The paper overlay prevents distortion or shearing of the plate and brings up the intermediate tone values, which are of special importance in fine half tone work.

What is claimed is:

The herein disclosed method of incorporating the make-ready in an electrotype or similar printing plate and which comprises taking a proof from the printing face of the plate on overlay paper, reversing said proof and registering the same in reversed relation on the back of the plate with the corresponding printing areas on the face of the plate, temporarily securing the plate in correspondence with the registered overlay proof on the back of the plate, said raised portions sinking to a corresponding extent into the lead-like face covering layer of material, stripping the overlay proof paper from the back of the raised plate and then shaving the impressed back of the raised plate to restore it to the original or intended thickness for use on a printing press.

WILLIAM SAUNDERS.

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