US 2722261 A
Description (OCR text may contain errors)
Nov. 1, 1955 H. L. BISHOP 3 3 DEVICE FOR USE IN MANUFACTURING ELECTROTYPES Filed Aug. 10, 1954 IN V EN TOR.
HIS ATTORNEYS United States Patent 'OfiFice 2,722,261 v fatented Nov. 1,1955
DEVICE FOR USE IN MANUFACTURING ELECTROTYPES Homer L. Bishop, Dayton, Ohio, assignor of thirty per cent to Earl E. Stansell, West Carrollton, Ohio Application August 10, 1954, Serial No. 448,910
' 6' Claims. (Cl. 153-32 This invention relates to a device for use in manufacturing electrotype plates and more particularly to a device for maintaining a high degree of accuracy in the size of electrotype plates during the curving process.
When the electrotype plate is subjected to the curving process, distortion of the impression on the plate is inevitable, due to stresses set up within the shell and backing metal when the curving takes place. curving process, unless some means is used to prevent, actual stretching of the shell occurs on its surface, and distortions occur due to pressures set up within the backing metal. The fidelity of the impression is thus ruined.
The importance of maintaining uniformity in the size of a series of shells is particularly important in color printing where perfect coincidence of images is necessary to prevent overlapping.
The object of the present invention is the provision of a device or curving frame for maintaining the shell exactly at its original length, and further to provide for even curving of the backing metal so that no buckling occurs from pressures which are set up within it, and no distortions of the image on the shell occur from this cause.
A further object of the invention is the provision of means for preventing stress in the backing metal, and means for preventing the lengthening of cracks once they are formed.
A further object of the invention is the provision of a device for holding a shell and backing during the process of curving, and one wherein the shell and backing are maintained at a set of predetermined dimensions during the curving process. This includes the length of both the inside and outside circumferences.
A further object of the invention is the provision of a device for use in the curving process of electrotype plates which provides for correction of inaccuracies in the size of the electrotype plates, so that accurate dimensions and an accurate curvature are obtained in the finished product.
Other objects and advantages reside in the construction of parts, the combination thereof and the mode of operation, as will become more apparent from the following description.
In the drawing,
Figure 1 is a perspective view of an electrotype plate comprising a shell and backing, held within the device of the invention.
Figure 2 is a schematic view showing a shell and backing of an electrotype plate secured in the device of the invention, and being passed through curving rollers.
Figure 3 is a cross sectional view of the device of the invention after it has been subjected to the curving process.
Figure 4 is a schematic view of the electrotype plate after the curving process.
Referring more in detail to the drawing, a form or curving frame, generally indicated by the numeral 10, consists of a pair of steel retaining bars 12, a bendable steel plate 14, a metal having high tensile strength, and an elastomeric enclosing member 16.
The steel bars 12 are shown as riveted at 18 to the steel plate 14; but the attachment can be made in any desired manner.
As will be noted in the drawing, the bars 12 are quadrilateral in cross section; the inward or facing edges are formed at an angle to the normal. This angular shape of the bars functions as a holddown engaging beveled margins of the electrotype shell so as to prevent the ends from curving away from the plate 14. In the present instance, and for present uses, this angle is 12 from the normal, making the angle between the plate 14 and the slanted edge 20 an exact angle of 78. However, the invention is not limited to this specific angle in that the angle'may be increased or decreased within certain limits.
The enclosing member 16 is made of rubber, or other elastomer, and receives the form 10, enclosing it on all In the usual sides with the exception of the upper surface of the bars 12 and the space between them.
The electrotype 22, consisting of the shell 24 and backing metal 26, of soft metal, such as lead, as is common in the art, is placed in this space by sliding it in from an edge portion. The ends of the shell and backing are beveled at an angle to coincide as nearly as possible with the 78 angle between the plate and the retaining bars. If there are inaccuracies in this operation, and the abutting ends do not accurately coincide, this inaccuracy is cared for and corrected during the curving process.
During the curving process the shell lies flatly against the surface of the steel plate, and its ends fit accurately to the inward surfaces of the bars 12. The shell is thus protected against anystretching or other change in size,
and the image it carries on its surface remains completely and perfectly intact, and free from any sort of distortion.
The form 10, carrying the electrotype plate is passed between suitably arranged curving rollers. Figure 2 shows an inner roll 28 and a pair ofouter rolls 30. The present invention is not limited to any specific number or any specific arrangement of rollers, or, in fact, to any specific curving process. The important thing is that the exactness of the impression upon the shell remains intact in any curving process that is desired to be used.
In Figure 3 is shown the form and the electrotype plate after they have emerged from the curving rollers. The outward ends of the form are now sprung downwardly, and the finished electrotype plate is released.
When the curving is finished and the electrotype plate, together with the steel plate 14 and the enclosing elastomer 16 have emerged from the rollers, the plate 14 and the curving frame are held in curved position due to the fact that the inclined margin 20 of the bar 12 is held by the beveled margins of the curved electrotype plate 14. By merely deflecting one end of the curving frame so as to place a reverse curve in the portion of the curving frame adjacent the bar 12, this bar then clears the end of the electrotype plate. As soon as this takes place, the curving frame shapes into a straight position, ejecting the electrotype plate.
When using multi-color electrotype plates, it is very important that all of the electrotypes register. During the process of casting the backing metal on the shell, the shell may be distorted due to stresses set up, caused by temperature changes and shrinkage when the backing metal solidifies and cools. That being the case, even though all of the shells of a set of electrotype plates used in multi-color printing may be identical in dimensions before application of the backing metal, the resulting electrotype plates may not be uniform in length. If, for example, one electrotype plate is shorter than another of the same set, the longer one may be trimmed to size to fit between the retaining bars and the shorter one cut short. Due to the fact that the backing metal is placed in compression during the curving of the electrotype plate, the shell will stretch, so that the length of the shell, even though & short, will stretch sufficiently so as to be equal in'length to the Qthcr :electrotypeplate which was origina1ly longer. -By -the apparatus disclosed herein, ;it is therefore possible to compensate for irregularities resulting from, the casing of the backing metal.
,In curving an electrotype, the backing metal ,is compressed. ,In the electrotype shownherein, a plurality of substantially conical holes 40, arranged in rows and tiers in the-back side of the backing metal, provide pockets into ,which some of the surplus metalcaused by the curving operation mayfiow, thereby-reducing the diameter of theholes. furthermore,these holes limit-the cracking of the,eleotrotype plates and thereby prolong the lifeof the electrotype plates. If a crack develops, it will developin the weakest areas. This, of course, would be between two adjacent holes. However, when a crack does develop between two .adjacent holes, the .holes will limit the length of the crack, so that the crack will not-extend across a large area of the electrotype plate, resulting in failure. This has been more fully describedin my copending application Serial No. 448,911, filed Aug. 10, 1954, for Device for Use in Manufacturing Electrotype Plates.
Due to the fact that the electrotype plate is substantially equal ,in thickness to the thickness of the steel plate 14 and the elastomer or enclosing member 16, it can readily be seen that the face of the electrotype plate lies in a neutral plane ,where, if it were bonded to the steel plate 14, it would receive the maximum shearing stresses, assuming the materials to be homogeneous throughout.
Although the preferred embodiment of the device has beendescribed, it will be understood that within the purview of this invention various changes may be made in the form, details, proportion and arrangement of parts, the combination thereof and mode of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claims.
Having thus described my invention, I claim:
1. A device for use in the manufacture of electrotype platescomprising a bendable steel plate, a pair of metal retaining bars positioned in parallelism and secured to said plate, the inward facing edges of said steel bars being so inclined as toform an angle of 78 with said bendable plate, anelastomeric form partially encompassing saidsteel plate and said parallel bars, said parallel bars forming avspace for confining the shelland backing of an electrotype plate.
2. A device for use in the proces of curving electrotype plates, which comprises a bendable steel plate, a pair of steel bars placed in parallel position and secured to said plate, the inner facing edges of said bars forming an acute with said bendable late, said bars forming a space for holding the shell and backingmetal of an electrotype plate,
3. A device for use in the process of manufacturing curved electrotype plates having beveled margins including a shell and backing metal, said device comprising a bendable steel plate for flatly supporting said shell, a pair of retaining bars secured to said plate, and placed in parallelism, the inward facing walls of said bars being formed at an angle to the normal so as to snugly .fit the beveled margins of the ,electrotype plates, an elastomeric enclosing member covering all areas of said steel plate lying outside the space occupied by said electrotype plate.
4. A device for use in the process of manufacturing curved electrotype plates having an, impression .carrying shell provided with backingtmetal .on the rear surface ,of theshell, the ends.of the plate'beingbevelled, saidtdevice including a sheet of metal that is bendable and that has high resistance to elongation .as compared with the backing metal, a pair Lof plate retaining bars extending across said sheet of metal adjacent the .ends thereof and .fixedly secured ithereto, said bars extendingparallelto each other, the tinwardly facing edges of the bars being formed at an acuteangle with respect .to the adjacent portions of the shell-.0f-metal, so thatas thebevelled ends of the plate are positioned against the inclined facing edges of the bars, these hold theplate against the sheet of metal.
5. A device accordingto claim 4 wherein the side of the sheet of,met-al opopsitethebars iscovered with an elastomeric material permanently secured to the metal, the combined thickness of the sheetof metal and the elastomeric :material being substantially equal to the thickness of-the plate.
6 A device according toclaim4 wherein an elastomeric member .encloses:the sheet of metalon all sides excepting the upper surface of :the :bars and the space between the bars.
References Cited in the file of this patent UNITED STATES PATENTS 395,488 Dale Jan. 1, 1889 1,173,363 McCarroll Feb. 29, 1916 FOREIGN PATENTS 169,486 ,Germany Apr. 5, 1906