US1083890A - Stereotype. - Google Patents

Description

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WITNESSES v WA/Q jimmy/g;

J. J. 0. SMITH.

.STEREOTYPE.

APPLICATION FILED JU'LY25, 1910v Patented J an. 6, 19.14.

UV VEN TOR A TTORNEYS UNITED STATES PATENT OFFICE.

JOHN J. 0. SMITH, 0F .PASSAIC, NEW JERSEY, ASSIGNOB T0 IAUL M. HAMMALIAN, OF

HACKENSACK, NEW JERSEY.

STEREOTYP'E.

Specification of Letters Patent.

Patented Jan. 6, 1914.

To all whom it may concern:

Be it. known that I, JOHN J. 0. SMITH, a citizen of the United States, and a resident of Passaic, county of Passaic, State of New Jersey, have invented certain new and. useful Improvements in Stereotypes, of which the following is a specification.

This invention relates to stereotypes and particularly stereotypes formed of cast aluminum or of a cast metal having aluminum as its characteristic component.

In the accompanying drawing, which forms part of this application, the figure 1s a perspective view of a steneotype construct ed according to my invention.

Stereotypes at present employed are formed, either by castin type-metal against 1 a matrix of paper mac or by electrotypmg on a wax or similar impression,. the electrotype shell being afterward reinforced or backed by type metal. I

A great desideratum in the of making stereotypes has been to produce a stereotype of harder metal than the type-metal or electrotype plates commonly used, which are heavy in weight and soon become defaced loy wear and usage. Further, since it is desired to use cuts, illustrations, type matter and the like in many different publications in different and remote places and at as nearly the same time as. possible, the cost of transportation, particularly where sent by mail, as is frequently done, is, owing to the weight of the ordinary type-metal stereotypes, an item of considerable expense, which my invention is intended to overcome.

I have found that aluminum, or an alloy consisting principally of aluminum, possesses characteristics and properties rendering it eminently suitable and desirable for stereotypes. Among such properties may be mentioned its ability to make a good casting of the character required for stereotypes; its rigidity, hardness and durability;

its ability to make a good printing surface which will wear well-and permit comparatively roughusage, and which will not oxidizeand will be substantially acid proof; and its lightness in weight;

The relatively high melting temperature of aluminum, and the difficulties encountered in preparing a mold to meet the conditions required for making stereotypes of this metal, and the impossibility of making elec if trotypes of aluminum the frame.

adhesive surface to have heretofore pre eluded its use for stereotypes.

To successfully produce stereotypes of this metal, the molding composition used must not only possess the requisite characteristics of withstanding the heat of the molten metal to be cast therein when the mold is formed without cracking or checking, but it must also possess such tenacity that it will, when set, withdraw absolutely clean from the patterns and without distortion. Furthermore, it must be of such a character that it will enter the finest detail and lines of the design and reproduce a sharp and perfect impression. It will be obvious that even the finest cracks or a slight amount of shrinking or Warping will destroy the mold and make it impossible toprocure a good casting therefrom, particularlywhen it is considered that themetal is cast in the molds under pressure.

Molds heretofore employed for producing metal castingsand stereotypes do not satisfy the above requirements.

To produce aluminum stereotypes in the best manner now known to me, .I preferably employ a molding composition of my own invention formed of clay, asbestos fiber and plaster of Paris, (which composition is fully described in Letters Patent of the United States, No. 950,355, issued to me) and then proceed as follows: A mold frame is provided having sides adapted to inclose the molding space and the patterns, and a plate, preferably of steel, supported by said sides and extending over the space inclosed thereby. Said plate, which, as aforesaid, is part of the mold frame, is perforated or provided with a plurality of apertures, through which the molding material is poured as hereinafter stated. Said frame is preferably shallow so as to take very little molding material, and so as to form a thin mold, the strength and rigidity of which is derived from the metallic frame. The frames 1 have employed are not over three-eighths of an inch thick, including the perforated plate. For use with the said frame I provide a base of somewhat greater dimensions than This base may he of wood or any other suitable material or may form the topv of a table or "work bench. On its upper surface, this base is rovided with a nonwhich'the molding mato become confined in the cavities and lines.

terial Lwill not stick, as, for example, a

' smooth rubber sheet.

as may be desired, and according to the dimensions of the mold frame employed. The patterns will preferably be arranged with sufiicient space between them to allow for the necessary gates or sprues, as will be understood'by any one skilled in the molding or casting art.

- Having arranged the patterns and the blocks on plates forming the gates and sprues for the mold, I coat the faces thereof with a thin film of separting medium to in-.

sure a clean separation of the mold from the patterns. For this purpose I preferably employ good sperm oil, applied to the sur-' face of the patterns with a stiff brush so as to reach and coat every cavity and deep line of the pattern. This coating of oil or the like, while necessary to insure clean separation of mold from patterns, has the disadvantage of increasing the tendency of air of the design, thereby preventing the plaster composition from entering and thus producing a defective mold. The repellent or antagonistic character of the oiled surface against the water of the fluid plaster composition tends to keep the latter from flowing into and occupying the deeper recesses and lines of the pattern. It will be understood that for stereotypes the design or pattern is fine and intricate, presenting many hundreds of small recesses and cavities on a surface less than fifty square inches, and in order to produce a successful stereotype a faithful reproduction of every line and cavity of the design is required. Agitation of the plaster composition, after it has been cast upon the pattern and while still fluid, has been proposed, but this is only effective in designs which do not present the intricacies of detail possessed by stereotypes and is ineffective for such moldings. Furthermore, if agitation be attempted. for the purpose of removing the confined air in the cavities, as, for instance, by applying a brush to drive the same out, the oil film becomes removed in places where reached by the brush, and this results in the mold composition sticking to the pattern and producing defects. To overcome these difliculties, I wet or moisten the oiled surface of the pattern with a fluid which will lie uniformly thereon and not be either repellent or antagonistic to the water of the molding composition. For such fluid I have found wood alcohol to give good and satisfactory results. Having therefore coated the patterns withoil, as above stated, I then apply wood al ohol to the oiled surface- This is preferably done by applying the wood alcohol in a fine spray by means of an atomizer. Care should be taken to apply no more alcohol than is required to wet the oiled surface, as an excess of alcohol would be likely to delay the setting or hardening of the mold. a The mold-frame is then placed over the prepared patterns and the same is held in position either by arranging Weights around its edges or by clamping it to the base,-or in any convenient way. The molding composition having been prepared, is now poured into the mold or frame through the perforations or apertures therein. Sufficient of the molding composition is poured in to completely fill the interior of the mold frame and to rise through the apertures or perforations and to overflow the same. When the composition has partially set, say, in about ten minutes, the surplus composition is removed by striking it off, by means of a stick or bar, level with the top of the perforations or apertures. In this way, the

frame becomes embeddedin and forms part of the mold.- After about ten minutes more, the composition sets ,sufliciently hard to permit the mold tobe removed from the base board and patterns. This removal of the mold should be done with care and I prefer- ,ably provide means for lifting the frame equally at all points. The mold may now be placed at once into. a drying oven of any suitable kind, heated by gas or other means of heat, to a temperature of about.600 F. The,, molds sustain this degree of heat without any danger of cracking or any other injury. They are left in the oven for a period of from two to three hours, at the end of which time the moisture and water are all expelled therefrom. After having been dried, the molds are ready for the casting operation. It will be apparent that the mold is constituted by the thin layer of molding composition which carries the design or impression, together with the perforated moldframe. The latter gives great stiffness, rigidity and strength to the mold, not only protecting it from damage but enabling it to resist the pressure to which his subjected in the casting operation. 7

In a co-pending application, Serial No.

518,319 (now Patent No. 965,242, dated July 26, 1910) I have fully described and illustrated my said process for making molds for stereotypes, and in another co-pending application, Serial No. 487,169 (now Patent No. 965,241, dated July 26, 1910), Ihave fully described and illustrated apparatus for making stereotypes, which process and apparatus are applicable to making stereotypes of aluminum.

When the molds are ready for casting'as above stated, fluid metal is forced into the molds under pressure. I preferably employ a machine or apparatus for so casting the metal. ltlachines or apparatus of this type haw. long been known and have been in vented by myself and others. (See for instance, United States Letters Patent, No. 70,038 granted to Michael Smith, October Q2. 1864'; No. 477,231 granted to myself and Victor E. Smith, June 21st, 1892- and No.

591.430 granted to myself October 12th,?

1997.) In machines of this character, the fluid metal .is forced into the molds under what is substantially the equivalent of hydraulic pressure, which forced the metal into the fine details and lines of the designs, enabling, thereby a perfect casting to be obtained.

I thus produce a stereotype of aluminum, or of an alloy thereof consisting principally of aluminum, of a high degree of perfection, in a rapid and economical manner.

Having: described my invention, I claim:

1. A cast metal stereotype composed of aluminium.

A. cast metal stereotype having aluminium as its characteristic component.

3. A cast metal stereotype made of an alloy of which alun'linium is the principal component.

In witness whereof, I have hereunto set my hand to the foregoing specification in the presence of two subscribing witnesses.

' JOHN J. C. SMITH.

\Vitnesses CHARLES FELTUAN, J. MoLAUonLIN.

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