US1216388A - Method of shaving stereotype printing-plates. - Google Patents

Description

1,216,388. Patented Feb. 20,1917.

H. A[ W. WOOD.

METHOD OF SHAVING STEREOTYPE PRI NTING PLATES;

APPLICATION FILED MAY 20. 1915.

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' UNITED STATES PATENT OFFICE.

HENRY A, WISE WOOD, OF NEW YORK, N. Y., ASSIGNOR '10 WOOD NEWSPAPER MACHINERY'GORPORATION, OF NEW YORK, N. Y, CORPORATION OF VIB- GINIA.

METHOD OF SHAVING STEREOTYPE PR1] [TING-PLATES.

Specification of Letters Patent.

.Applic'ation filed May 20, 1915. Serial NC. 29,319.

To all whom it may concern:

Be it known that I, HENRY A. W se \Vooo, a citizen of the United States, residin at New York, in the county of New York and State of New York, have invented a new and useful Method of Shaving Stere otype Printin -Plates, of which the following is a speci cation.

This invention relates to a method of finishing stereotype plates on the back and the principal objects thereof are to provide for preventing distortion of the plate by the shaving operation and especially for. preventing the-*flattening out of the portions of the plate which are provided with elevations on their printing surfaces.

Reference is tobe had to the accompanying drawing which is a sectional perspective view of the shaving arch of a machine for finishing a semi-cylindrical. stereotype, printing plate shown as provided with means for carrying out the method which is the subject of this invention. 7

As is well understood, all stereotype plates for newspapers are shaved to thickness, the plate, if a curved one, being held against a smooth semi-cylindrical arch for this purpose. Recently it has come to be the practice to make .halftone cuts in v'arying heights. In this case" the foreground and the solids are forced above the surface of the plate so that they are higher than the back-groundand the high lights of the plate. As these higher portions bring to hear more pressure on the sheet than the light portions they print more distinctly. In this way the. foreground and solid portions of the picture are sharp andblack, whereas the background andhigh lightsare less clear cut and appear graya However,

owing to the fact that the usual method of shaving plateshas been retained ,in connection wlth plates made as described above,

the pressed-up effect referred to is-destroyed in shaving This is due to the'following facts The matrix is usually made of paper which has been molded from the page of type by means of a felt blanket pressed against the type. After being molded, the matrix is dried in contact with the type and 'when removed it is found that the ressed-up portions (if the half tone have een precisely reproduced in the face of the matrix, which is what-is required, but it tions of the plate from being fiattene Patented Feb. 20, 1917.

into the casting box and a plate-is made from it, it is obvious that the metal bears against the inside face of the matrix with considerable pressure. Therefore, these projections or depressions become somewhat flattened and equalized. This naturally reduces the pi essed-up effect but still some of this effect r1 mains and is found in the cast plate. But when the cast plate goes to the shaving machine in a flaccid condition, as it should, tie shaving knife, which is invariably made dull, forces these pressed-up portions of the plate so hard against the shaving tll'Cil that they become flattened or otherwise marred.

' It is the (bject of this invention to avoid these difficulties due to the shaving operation. This invention relates solely to the shaving operation.

-Referring now to the drawing, it will be seenthat the semi cylindrical plate A'is shown in an arch Bpf the usual type. A

shaving kn fe' C is shown on a rotating knife'ca'rrier D. The plate is shown as supported on r)llers F and a lifting clamp G, a

as is the usi al practice. The plate is shown as provided with the usual finishing strips H and the knife C isshown in the actof shaving off these strips to a uniform semi- .cylindrical ;hape in order that the interior of the plate may fit the printing cylinder of the press. As so far described in this paragraph, these features are old.

In order to preservethe pressed-up orotherwise narred, I insert into the shai'ing arch B with the plate a backer This backer may be the matrix from which the plate was cast, or a duplicate thereo'f, but at any rate, it occupies t e exact position on the plate (ccupied by the casting matrix during-the casting operation. In thisway the projections mV and depressions m of the concave S111 face of the matrix fit res ectivel'y the d epressions a and the projections a on the co nvexsurface of the plate.

Although I have referred to de ressions on the matrix'and projections on t e plate,

'it is to be understood that these are merely relative terms, as they really represent the normal surfaces of. these two parts that is, the surfaces as they would be without the alteration due to the half-tone process, as carried out at present. This matrix, therefore, lies between the plate and the arch during the process of shaving and prevents, the distortion or marring of the ,plate by pressure on it from Within. Therefore, all the pressedup effect is preserved in the plate and the plate will emerge from the arch in the condition on its type face in which it entered it. This is an important feature because it permits of the preservation of the additional distinctness secured by the abovementioned method.

It will be understood, of course, that while I have called this backing-up sheet a matrix, it can be a'true matrix or a dummy matrix, having the main characteristics of the matrix but not necessarily exactly duplicating all the more minute depressions and projections thereof, if it is found convenient to make such a dummy matrix. Even in course. If a dummy'or duplicate is used,

' the casting operationcan proceed while the shaving; operation is going on, thus saving a' IIllitGIlfllflInOllIlt of time.- w

Although I have shown and described the method as used in connection with a shaving arch, it is to be understood that it of the invention as ex-' -understood; For example, the method can be applied tofflat plates, and can be carried out inapp'a'ratus such-as shown in my ap lications, Serial Nos. 13,733 and 18,248, led March 11th and March 31st, 1915, respectively. I

'It will be ties above mentioned are entirely counteracted hy thismethodwithout adding matcrially to the expense thereof and that the seen, therefore, that the dilficulmethod which is the subject of this invention (although designed for use in connection with 'plates for the production of halftone cuts) is not limited thereto and can be used for the purpose of preserving any deli- ;cate or rough irregularities of a printing plate ofaany kind. Therefore, I do not wish to be'limited to the exact application of the method herein shown and described except as defined in the appended claims, but what and projections on the printing face of the plate, and shaving the back side of while held in that condition.

2'. The method of shavingaprinting plate, which consists inapplying to the printing surface thereof a du licate of, the matrix on which it is cast, orcing' the plate with said duplicate against'a surface having the samegeneral shape as thelplate, and shav the plate ing the rear side of the plate while held in that condition.

3. The method of shaving a semi-cylindrical stereotype printing plate, which consists in applying to it a matrix on the type face thereof, said matrix fitting. the'type surface of the plate, moving the plate and matrix into'a curved shavin arch having a smooth semi-cylindrical inner -surface-,-

pressing the plate with the matrix thereon against said arch, and shaving the surfaces of the finishing strips onthe back of the plate while the plate is held in the arch.

' In testimony whereof I have hereunto set my hand, in the presence of a subscribing witness.

Witness: 1 'Bnon'wnn .Jonns."'

1;. a WISE WOOD.

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