US909832A - Method of bending electrotype-plates. - Google Patents

Description

B. F. UPHAM.

METHOD OF BENDING ELEGTROTYPE PLATES. APPLICATION FILED DEC. 17, 1906. RENEWED SEPT. 30, 1908.

Patented Jan. 12, 1909.

' l ng L T Ana/6242i 1/ BMW i v E UNITED s rarns PATENT OFFICE.

BURT F. UPHAM, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO SOUTHGATE MACHINERY (30., OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

METHOD OF BENDING ELEGTItOTYPE-PLATES.

Specification of Letters Patent. Appliuationflled December 17, 1906, Serial No. 348,313. Renewed September 30,

Patented Jan. 1 2, 1909.

1908. Serial No. 456,396.

type-Plates, of which the following is a full, clear, and exact description.

In the process of bending electrotype plates for use upon cylinder presses, it has hitherto been customary to lay the electrotype shell face downward upon a flat surface; then back the same with melted alloy to a thickness of substantially half an inch;

then, after the alloy has well hardened, to plane it down until shell and all are brought to a total thickness of three-sixteenths of an inch; and, finally, to place the same face downward within a concave mold of the desired curvature, and press the backed shell to conform therewith.

For certain kinds of work, as for presses employing both flat and curved printing-surfaces, this method is highly objectionable, inasmuch as in the process of bending, the electrotype shell is appreciably elongated, to an extent amounting in the larger plates to fully an eighth of an inch.

The fiat plate, used in conjunction with this curved one, not being thus elongated, the two will not match, and, hence, Where one impression is designed to be superim= posed upon the other, as in color work, very imperfect results must follow.

I have found that it is not practical to place the electrotypc shell in a concave mold corr espondingin curvature to the cylinder upon which the electrotype is to be used, and then to pour therein the melted backingmetal to the required final thickness, especially for large plates, on account of the failure of the molten metal to flow with uniformity to the extreme limits of theplatc, and to consequently form depressions and blow-holes whereby the plate is rendered worthless for withstanding the heavy pressures towhich the printing surface is subjected. Neither is it practical in the usual printing establishment, to back up a properly curved electrotype shell to the custonr ary excessive thickness, and then to plane down the backing togage by some form of planing machine. A machine for thus planing a cylindrical concave'surface would be too complicated and expensive to be owned and operated by such establishments.

The object of my invention is the production of a process whereby electrotype plates may be made of the proper curvature with.- out such undesirable elongation, and hence fit for use in conjunction with fiat plates:

My process consists essentially in backing up the electrotype she1l,'0r other printing surface, and then treating the same in accordance with a process certain steps of which include two bendings opposite in direction; the last bending being to a curvature disposed to fit the printing surface to the cylinder upon which it is to be used, and

- the process serving to eliminate superficial distortion of such surface. By this method, the contractionof the first bending acts to entirely neutralize the elongation of the second, and so produces a curved late perfectly nlatclung the original fiatfp ate.

I have devised two methods or carrylng this process into effect, the first consisting in backing u the electrotypc shell in a con-. cave mold; than bending 1t flat and planing it to gage, and finally curving it in the cus tomary manner.

My second method consists in backing up the electrotype shell in the usual manner upon a fiat surface; then curving it face inward upon a cylindrical surface and routing or turning it to gage, and finally bending it back to a flat contour, and then curv-- ing it in the usual way. 2

Referring to the drawings forming part of this specification, Figure 1 is .a side elevation in diagram of the mold used in the first step of my first process. Fig. 2 illustrates the second step in'said process. Fig. 3 shows the mold used in the third step of said process; Fig. e f-illustrates the first step in my second process. Fig. 5 shows the secand step in this second process, and Fig. 6

shows the final step therein. F

In Fig. 1 10' designates the concave mold used in the first step of my first method; 1, the electrotype shell; 2, the lead backing poured thereon. to half-inch thickness usually preferred, and 11 is the shaper for causing the upper surface of the lead to be concentric with the printing surface. From this mold, the plate is removedto a flat surface 12, upon which it is laid face-downward and :torced. to conform thereto by suitable pressure. ing thus flattened, it is evident that the previously'convex surface must receive a substantial compression or shortening in the operation; the extent of such contraction being of course controlled by the curvature of tee mold 10 and the thickness of the plate. In this condition the plate is planed down to the quarter or three-sixteenths of an inch thickness'l equired to fitit for the printing cylinder, as indicated by the dotted ne 3. It is then laid in the mold 15 face downward, and brought to its final shape in the usual manner; the curvature of this mold being 01' course of equal radius to that of the printing surface; As the plate is thus bent to its final curvature, its printing surface is elongated to an amount exactly equal to its contraction when flattened from its originalcurvcd form,

The secret of. making the two opposite distortions exactly equal each other, and thereby bring the printing surface back its original dimensions, is to have the origi nal curvature of the plate multiplied by its original thickness equal its final curvature multiplied by its final thickness; and as curvature is inversely proportional to radius,

7 the original radius of mold multi lied by the surface 20, with its face inward, andbentc final thickness of. plate shoul e dnal the final radius of mold multiplied by original thickness of plate. Hence the curvature of the first mold 10 should be much flatter than the final mold l5.

My second method, and the one whichl' consists in laying the electro-s hell face'd'ow'nward upon a flat surface 12, and then ppuring the melted alloy backing thereon to the usual half-inch in thickness. This plate when coolis then-removed to the cylindrical into conformity therewith, and, while there, turned 01' routed down to the desired quarter or three-sixteenths inch thickness, as indicated by the dotted line 3. This thinned plate is now, bent back to its original fiat shape, and ap lied to the mold 15 face downward, an brought to its final curvature.

During the bendings, from fiat to concave;

-and from conca'veto convex, the contraction of the first must be made to exactly equal the. elongation of. the second; but inasmuch as the final beudings after thinning are from The plate beconcave toconvex, the cylinder 20 must be niuch less fiat than the original mold 10 in the first method, and above formula cannot now be applied, but the radius of the surface ZOmust be very nearly that of the; final mold 15, depending upon whether the plate is thinned from one-half to one-fourth or from I one-half to three-sixteenths. li the'latter, the surface 20should be flatter than the surface 15. V j

Although I have specified this process as applicable to electrotype plates, I donot restrict myself thereto, as the -method is equally valuable for other metal-backed printing surfaces. Hence, in the claims, I employ the term electrotype, in all cases Where itssignification is not otherwise restricted, to designate any metal-backed printing surface. y i

The claims herein are specific to the more generic ones in my companion application Serial No. 409,805.

What I claim as my invention. and for which I desire Letters Patent is-as follows,

' ing an xcessively backed printing surface to super ially distort the same, then thinning the backing to gage, and finally bending the same to the desired curvature, whereby superficial distortion of such surface is elimi nated.

The herein described methodof preparmg electrotype plates consisting in first backing the electrotype shell with an excessive thickness of fusible metal 5 then curving the same to compressthe printing surface thereof-g thinning the backing down to its workingo thickness; and finally curvin the plate to elongate its printing surface an bring it into conformity with the printing cylinder;

4. The herein described method ofprepan ing electrotype plates for use upon cylinder presses, the same consisting in first backing up the electrotype shell upon a flat surface;

second, bending the same face down upon a cylindrical surface, and" then thinning the backing to its working thickness; and finally bringing theplate to its desired convex curvature. I

5. The herein described method of preparing electrotypeplates for use upon cylinder presses, the same consisting in first placing the electrotype shell upon a fiat surface; backing it with lead to an excessive thickness; bending itlipon e, cyfin irical of greaterradius than the iesirei printmg surface; with its said shell thinni the backing to the esized Wa king ihicii mess; and finaliy bending tbs plate to its 61% sired curvature in a pre er comma mclcL in testimonvthat E 22 foz'egsing invgntien, I have hereunto set my hzmrl this Lth Gmy of December, 1906. f

BURT F. UZPHAM.

Witnesses:

- A. B UPHAM, L, L. EANGQ.

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