US1191353A - Composition and mold for stereotypes. - Google Patents

Description

I I EEIEE-EE msx I J. J. C. SMITH.

COMPOSITION AND MOLD FOR STEREOTYPES.

APPLICATION FILED AUG.2. 1911.

Patented July 18, 191-6.

I I 1 vv' 1 aftozuci en e tis.

JOHN J. C. SMITH, OF PASSAIC, NEW JERSEY, ASSIGNOR TO PAUL M. HAMMALIAN', OF Li-IACKENSBLCK, NEW JERSEY.

COMPOSITIGN AND FOR STEREOTYPES.

Specification of Letters Patent.

aatented July 18, 1916.

Application filed August 2, 1911. serial No. 642,006.

To all whom it may concern: 7

Be it known that 1, JOHN J. C. SMITH, a citizen of the United States, and aresident of Fassaic, county of Passaic, State of New Jersey, have invented certain new and useful Improvements in Compositions and Molds for Stereotypes, of whichthe following is a specification.

This invention relates to improvements in molds and composition for molds for stereotypes. In general terms, my invention relates to the more rapid, facile and economical production of stereotypes formed of cast aluminum or other hard metals having very high melting points.

More particularly my invention relates to the rapid, facile and economical production of molds for casting stereotypes of aluminum or other hard metals.

In producing stereotypes, time is a very important element because stereotypes are required to be completed on very short notice, and itis therefore important.and desirable to rapidly produce a mold in which such stereotypes may be cast.

By the use of my invention molds may be formed by direct impression into a molding composition of a pattern, such as a form of set-up printing matter, half-tone, or the like, which molds will faithfully take and retain the fine, delicate and intricate outlines of such impressions of type matter, half tones and the like; separate perfectly and cleanly from the pattern without distortion; will be exceedingly thin, light in weight, contain a minimum of material, and be capable of easy handling and rapid drying; withstand the heat of molten metal at temperatures of from 800 to 1200 and be free from any tendency to char, crack, warp or check either during drying or whilethe casting operation is being carried on.

In the accompanying drawings which illustrate an apparatus for carrying out one form of my inventiomand in which similar reference characters designate corresponding parts throughout the several views, Figure l is a plan view of a forming plate preferably employed by me, the fabric base and the plastic material being spread thereon and plastic material being broken away .to show the fabric beneath; Fig. 2 is a plan view of a drying frame preferably employed by me in carrying out my invention; Fig.

\powder.

3 is a plan view of a mold, the cover or cope plate being partially broken away; Fig.4 s a cross-section of the forming plate shown in Flg. 1; Fig. 5 is a cross-section of the drylng frame shown in Fig. 2; and Fig. 6 is a cross-section of the mold shown in Fig. 3.

In order toproduce a mold having thecharacteristics above described, I employ a molding composition, the principal or characteristic constituent of which is an argillaceous material of fine texture and good tenacity and plasticity. I have found that fine, difi'use, potters clay, prepared in a manner similar to that used by potters for-crockery and the like, is well suited to the purpose of my invention and therefore prefer to use this material. I take this potters clay and mix it with about one-third its weight of asbestos fiber and about onefourth its weight of fine asbestos powder, using sufficient water as hereinafter described. In place of the asbestos powder, I

in the kind of potters clay or the substitution of another powdered fire-proof substance will not constitute a deviation from the spirit of my claims. The above mentioned materials, I mix with sulficient Water to form, by active stirring, a slush, and such stirring is continued until the long fibers of the asbestos fiber are thoroughly'divided and mixed with the clay. I then evaporate the surplus water in any convenient way, and knead the materialeither by hand or by suitable machinery until it assumes the'form of a plastic tenacious greasy-feeling substance, when it is ready for the next "step, which is to form it into sheets of suitable thickness.

It is well known that clay and clay compositions have a great tendency to shrink while drying or coming from their plastic conditions to conditions in which they are free from moisture and the shrinkage aforesaid, of course, is in all directions and is inch to the foot. A sheet of such material of suitable thickness for producing a mold for making stereotypes cannot, therefore,

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without cracking or distortion be secured to a stifi non-contracting base while drying as is done with wax on a metal plate in the electrotype process of making printing plates and it is impossible to handle such material unless a suitable base is provided therefor. It was necessary, therefore, to

find a material which would first act as a suitable base to hold the composition sheet in condition to be handled and secondly which would yield or accommodate itself to the movement of the composition during its contraction or shrinkage I discovered that a sheet of strong, speciallywoven cotton or hemp cloth was best suited for this purpose and answered all the requirements.

Preferably such cloth is woven rather loosely about the same as burlap, but the yarn out of which it is woven should be strong and free from knots so that the sheet or cloth woven therefrom will present an even, uniform and flat surface. I preferably take a sheet of this cloth, wet it, spread and smooth it down on a suitable metal plate so that it adheres to the same. I then take the composition described above which, as aforesaid, is in a soft plastic state and spread it on the cloth in any suitable manner, making sure, however, that the soft clay is forced into the interstices of the open-woven cloth and that the cloth and material are firmly stuck together. I preferably accomplish this in the following manner: I take a straight, level and smooth metal plate A, provided with guide strips a a, which project above the surface of the plate, as shown in cross-section in Fig. 4, a distance suflicient to provide a suitable bed for forming the composition sheet. In practice, the height of these guide strips above the surface of the plate isabOut three-sixteenths of an inch. On the plate A, .and between the guide strips a a, I lay.

' a sheet a: of said cloth which 1 wet and same direction.

smooth down to make it adhere to the plate. I then take the soft plastic composition in dicated by g and spread it on the cloth by means of a large trowel until it fills the space between the surface of the plate and the top of the guide strips, also allowing considerable surplus. Then 1 preferably take a straight metal bar', and resting it on the guide strips a a, draw it over the material and bring it even and level with the guide strips This spreading or smoothingbar should be drawn over the material in this manner several times, but always in the This manipulation of spreading and smoothing the material forces the same into the interstices of the open-woven cloth and such cloth and commenses A, and lay it on a straight fiat slab such as l have designated B in the drawings. This will keep the said sheet in-a flat position and assist in absorbing a portion of the moisture therein. After the sheet is removed from the plate, its surface is far too soft to take a usable impression of type matter or the like and it must be brought to a suitable condition by drying out a portion of the water until the composition attains approximately the hardness and plasticity of a piece of wax undera temperature of F. To bring my composition sheet into that condition I preferably proceed as follows: in order to prevent the sheet from warping and curling up at the edges I place thereon a metal frame C which rests on the margin or periphery of the sheet and is open at its center. The frame C is preferably notched or cut out, as shown, to form a plurality of small feet 0 send alternative open spaces 0' c, surrounding its edge. The feet a crest upon the margin of the composition sheet and the notches c c permit the circulation of air and consequent more rapid drying-thereof. This construction furthermore eases up the contact of the frame and permits the contraction of the sheet without injury, such shrinkage or contraction of the sheet, by the time it has come to a' state of plasticity to take the type-matter impression, being as aforesaid about one quarter of an inch'to the foot. The combination of the woven cloth with the composition allows such shrinkage without showing cracks or fissures. When the clay slabs have acquired the required plasticity to take a perfect impression, the surface of the clay slab is smoothed by means of a smooth polished trowel which imparts an even smooth and polished surface to the composition sheet, which is now ready to take the type matter impression.

The step of impressing the pattern con sisting of a form of type matter, half-tone or the like, into the composition sheet to form a mold or matrix differs from the procedure employed in making a wax matrix or mold for the electrotyping of printing surfaces only in. this way, that l a ply afine coating of sperm oil in the sur ace of the pattern by means of a brush. I lay the sheet on a straight smooth metal" plate the till - however, observed to keep the iron frame C sheet, place the whole under a press the same as used by electrotype plate-makers and apply a pressure sufficient to force the type or design of the pattern or type form into the composition of the sheet to the depth of type face or to the shoulder. After the impression is taken the pattern or type form may be easily removed and a perfect matrix is obtained. It will be obvious that, if the size of the pattern or type form is suflicient to cover only a part of the surface of the sheet, a number of impressions can be made alongside of each other on the same sheet to fill the same. WVhen the sheet has all the impressions desired it is preferably taken from the plate and laid on a hot steam table to more quickly drive off moisture. Be it,

on the impressed sheet so as to prevent warping and curling. In the course of ten to fifteen minutes on the steam table the impressed sheet acquires hardness or rigidity and becomes as stiff as a heavy paste board. It can now be readily and easily handled and will remain perfectly straight.

I remark here that the impressed sheet or matrix still contains somemoisture which would prevent the production of a sharp casting. To drive off the residue of 'the moisture, I place the impressed sheet or matrix in a drying oven heated to about 600 to 700 F. Heat of that degree will render the sheet perfectly dry so that when used as a matrix or mold, molten aluminum or other metal may be cast under pressure and a perfect and sharp casting of the finest outlines will result.

So far I have described only the formation of a sheet or matrix which contains only the impressions ofthe type faces or designs as deep as the type head an'd'have not yet indicated the method of providing for the thickness of the body of the stereotype plate. This is done by means of the following easily understood mechanical arrangement shown in Figs. 3 and 6 of the drawings: I

preferably provide each impressed sheet or matrix-with a blank margin N of about one inch all around. On this margin N I place a metal frame 0 of suitable depth and up on that frame, I place a cope slab or cover plate P which forms a suitable space Q between the impressed sheet or matrix proper and the cope plate P for the reception of the fluid, or molten metal, which is forced into such space through a suitable gate R.

The cope plate P is partly broken away to show the mold T.

Molds prepared in this manner maybe used in machines for casting metal under nressure in the manner fully understood by persons skilled in that mechanical art, and

types of which form the subject-matter of several Letters Patent issued to myself.

By reason of the improvements above described, I am enabled to produce a cast aluminum stereotype in a shorter period of time than has heretofore been possible and of an extraordinary perfection and fineness of. design.

The molding composition employed by me is of such character that it may first be formed into extremely thin sheets used by 4 composition in condition for handling the thin layersof this composition, so that the impression may be properly made and re- I produced.

It will be understood that the embodiment of my invention hereinbefore illustrated and described is simply my preferred form'of invention and is by way of illustration only and not of limitation to the precise details and steps disclosed. Many modifications of the same will suggest themselves to those skilled in the art Without departing from the spirit of my invention.

Having described my invention, I claim:

1. {A composition for molds for the purpose specified, consistin of approximately sixty-four per cent. of c ay, twenty-one per cent. of asbestos fiber and fifteen per cent. of asbestos powder.

2. A mold for casting stereotypes; said mold formed of a base of suitable yielding material and a layer of molding composition consisting of approximately slxty-four per cent. of potters clay, twenty-one per cent. of asbestos fiber and fifteen per cent. of asbestos powder.

, 3. A mold for casting stereotypes, said mold formed of a base composed of an open woven fabric and a superimposed molding I In testimony whereof, I have hereunto set my hand to the foregoing specification in the presence of two subscribing witnesses.

JOHN J. 0. SMITH.

Witnesses: v

GEORGE W. OHAnWIoK, HELEN V. HOLMES.

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