US965242A - Process for making molds for stereotypes. - Google Patents

Description

J. J. G. SMITH.

PROCESS FOR MAKING MOLDS FOR STEREOTYPES.

APPLIUATION nun SEPT. 18, 1909.

965,242. Patented July 26. 1910.

' fo'a'llwhom it may concern:-

PATENT creme.

JOHN J. o. em n te rgss x'rd nnw JERSEY, AssreNo'n' 'ro PAUL m. HAMMALIAN, or V HACKENSACK, NEW JEnsEY. w

' "'rrto ohjss Ion MAKING MOLDS roe 'STEREOTYPES; 1

$65,242: I Original application-"filed April-1, 1909,

Be it known that 7.,JOHN J. C. ,S1s-rrr1r, a citizen of the United States, and residing. at

' Passa'ic, county of Passaic, State of New for Stereotypes;

Jersey, have'invented new and useful Im provementsin the Process forMaking Molds and in order that those skilled" in the 'art may understand and practice" my invention- I specification, referencebemg had to the acgive the following companying draw-in g's, forming part thereof.

My invention relates generally to the production of cast metal "designs, but more particularly to making of new and improved stereotypes forthe"reproduction by ordinary printing processes of cuts, illustrations, de-

signs,

type-matter and the like. The invention has for-its objects the production of cast stereotypesnin: rapid and 'for the purpose,

improved process or method ofmaking'and' economical manner, and of niaterialsi'iheretofore not generally supposed to be SilliilblG and more particularly an producing molds for forming such stereotypes or cast designs.

Stereotypes at present employed are for-med, either by casting type-metal against a matrix of pap'ier mach, or by electrotyping on a wax or similar impression, the eleotrotype shell being afterward reinforced or backed by type-metal; A great desideratum in the art 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 by wear and jusage. duceTouts,. illustrations, type matter and Furthen's'i'nce it isdesired to reprothe like i any diiferent publications in difl'erent and remote places and at as nearly "thesame time as possible,'the cost of trans portation,"partic arly where sent by mail, as is frequently done, is, owing tothe weight of theordinary type-metal stereotypes, an item'ofjconsiderable. expense which my. in.

ployment harder and lighter; metals suitable for print- 7, iiig purposes require considerably higher temperature for melting, 'making' the use of papier maoh matrirr impossible andnecessit run the empldymeiit'of a refraet'orymaterial for the'same. In employing a mold Specification of Letters Patent. Patented July 26, 1910.

Serial No. 487,169. I Divided and this application filed September 18, 1909. Serial No. 518,319,

or matrix of refractory material, however,

further difficulty is encou'ntered'in that such molds are formed of the molding material in a plastic or semi-fluid state from whichit has to dry and harden, and this drying, in order to be sufliciently rapid, requires a heat of about 600 F. Underthese conditions fine or even large eracks make their appearance in ordinary molds. It will be 0 vious that even the finest cracks, or' a slight amount of shrinking or warping will destroy the mold, particularly when it is considered that the metal is cast in the molds under pressure, as it'is contemplated with 7 the. molds of my present invention.

I am aware that plaster molds have been employed for producing metal castings and stereotypes,but such molds ashaveheretofore been usedv have the disadvantage not only of not satisfyin the above requ1rement,.but of requiring sue 1 length of time to dry them by heat that their use for making stereotypes 18 out of the question, because stereotypes are required to be finished on very short notice, sometimes no more than three 1 or four hours,-a period insufli'cient evenito dry the ordinary plaster mold. Stilla .further difliculty to be overcome with molds of such-material is that the material oi the mold must be capable of entering the finest lines of a delicate or-intricate design and of taking and retainingimpre'ssion in a high degree of perfection, and also that itmust .be capable of withdrawal from the pattern without distortion and must se arate from the pattern erfectly and clean y.

In order t atmy resent invention may -;be more clearly un erstood I have "illustrated the means employed for carrying it out in the accompanylng drawings, in

Which- Figure represents a planview' of the apparatus employed, parts beingb'roken away to show underlying parts. igs. 2 and'3 are similar sectional views, the ap aratus being in position in Fig. 2 forthe 'eastin operation andshowing the mold form' on the patterns; Fig. 3sh'ows the first step in removing the mold. formed from the pattern. Fig. 4 is an underside View ofifthe formed mold. Fig 5 is a detail sectional view on anenlarged scale of'a 'porti'or'i of the mold plate. L

Similar characters of reference are apof a metal plate 2 of any desired or suitable size-say 16" by 20 or larger-easily handled and accommodated in the casting machine. This casting machine will be hereinaft-er referred to, but forms no part of my present invention. The plate 2 is preferably of steel as affording the requisite strength and stiffness, and also because the mold composition adheres well tov steel. Other metals or alloys, brass, for example, may be employed for this plate-if desired. This plate 2 is of openwork construction or foraminated or perforated to rovide openings or holes 3, the purpose 0 which will hereinafter appear. These holes may be tapered as illustrated in Fig. 5 if desired, so as to give the mold composition a better grip to'the frame. This will be desirable where other metals than steel are employed for the frame 1. Plate 2 is also provided with a rim or flan e t around its edge on one side thereof an secured thereto in any convenient manner, as by rivet-ing, brazing or the like. jOn one side the rim is interrupted, as atl5, forming an opening or gate for use durin the casting operation. This opening 5 is c osed, however,'in-the process 0 forming the mold, by means of a removable block 6, (see Fig. l) or in any'other convenient manner. The perforated plate 2 with, its rim' or flange 4 forms'a flask or mold frame 1, relatively shallow so as to take very little molding material, and so form a thin mold, the strength and rigidity of which is derived from the metallic frame. The frames I have employed are not over three-eighths of an inch in thickness, including theplate 2. At each corner the frame is provided with a thumb-screw 7 passing through a threaded opening 7 therein.

"For use with the'frames 1 I provide a. base 8 of somewhat greater dimensions than the frame. This base may be of wood or any suitable material, or mag) form the top of a table or work bench. n its upper surface this base is provided with a nonadhesive surface to which the molding material will not stick, as, for example, a smooth rubber sheet 9. 7

The manner of using the apparatus above described and the process of preparing a mold is *asfollows: I take the pattern or patterns P, P of which it is desired to make a stereotype or casting and fasten the same temporarily on the base 8 by means of brads, or in any other convenient manner. (See Fig. 1). One or a number of such "patterns may be so secured in place, as may be desired, and according to the dimensions of flask employed. In the drawings I have shown two patterns, by way of example. The patterns will be arran ed with sulhcicnt 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. These gates or sprues are formed by removably fastenin to the base 8 blocks or pieces 10 of suitable s ape,and of a thickness slightly greater than the patterns, but of less thickness than the depth of the mold frame 1 (see Fig. 2).

Having arran ed the patterns and the blocks 01' plates forming the gate and spruesas above specified, I coat the faces thereof with a thin film of separating medium to insure a clean separation of the'mold from the patterns. For this purpose I preferably employ good sperm oil, applied to the surfaceof 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 to become confined'in the cavities and lines of the design when the molding composition or material is poured or cast on the patterns, thereby reventing thesaid molding composition 'rom entering said cavities and lines 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 andwhile still fluid, has been proposed, but this is only effective in designs which do not present the intricacies of detail ossessed by stereoty es and is ineffective for such moldin s- *urthermo'rc, if-agitation be attem ted for thepurpose of removing the confine air in the cavities, as, for instance, by applying a brush to drive the same out, the oil film becomes removedin places .where reached by the brush, and this results in the mold com os ition sticking to the pattern and pro ucmg-defects.

To overcome these 'difliculties I wet or moisten the oiled surface of the attem with a fluid which will lay unifor y 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 with oil,as

above stated, I then apply wood aleoholto ters: Patent thereforYSer. N 0. 487,168, filed frameor flask is thenplaced over the prepared patterns and the same is held in po- SltlOXLBlthfil by arranging weights around its edges or by clamping it to the bas e, or in any convenient way.

' The molding composition having been prepared, is. now poured into the mold or frame through the openings 3. This moldmg composition must possess the requisite characteristics of withstanding the heat of the molten metal to be cast therein when the mold 1s formed without checking or 'cracking, since the finest crack .would be reproduced on the cast stereotype. This heat will lbeabout 900 F. The molding composition must possess such tenacity that it will, when set, withdraw absolutely clean from the patterns and without distortion. further it must be of such character that it will enter the finest detail and lines off the design and reproduce a sharp and ave invented a moldistics an have filed an application for Let- April 1st, 1909." As 'disclosure of this mold- .ing composition is not requisite to the understandmg and carrying out of the present invention, further reference thereto is not believed tobe necessary. Sufficient of the molding composition is poured in to completely fill the interior of the mold frame and to rise through the-openings 3 and 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 or outer face of plate 2. 'This leaves the composition filling the holes or openings 3, as shown in Figs. 5 and 6 in which-the molding composition is rep resented at M. After about 1O minutes more, the compositionse'ts sufiiciently hard to permit the mold to be removed from the base-board and patterns. Thisremoval of the mold requires great care. To enable the removing of the mold to be accomplished with certainty, and without damage, I have provided at each corner of the mold plate the thumb screws 7. By turning each of these screws slightly in succession and to a similar degree, the mold will be lifted from the base-board without any danger of defacing the molded impression, as is clearly illustrated in Fig. 3. The m old may now be placed at once into thedrylng oven. This oven may be of any suitable kind, heated by gas or other means of heat.

niolt l material itself consists of only a thin layer of the molding composition, the time required for drying is reduced to a minimum. After having been dried'the molds are readyfor 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 openwork mold frame or plate 2. 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 it is subjected in the casting operation.

I havecontemplated employing molds prepared in the manner above described in ma chines or apparatus for casting metal under pressure. Machines or apparatus of this type have long been known, and have been invented by myself. (See for instance United States Patents No. 70.038 of'1867, and No.

477,231 granted June 21, 1892.) In machines of this character the fluid metal is forced into the molds under what is substantially the equivalent-of hydraulic pressure which forces the metal into the fine details and lines of the designs, enabling, thereby, a perfect casting to be obtained.

It will be notcd that by having the molds of the construction described they are not only of sutlicient strength to resist the pressure to which they are subjected, but, what is an important consideration, the gases from the molten metal and also the air in the casting spaces find exit through the porous molding composition filling the holes in said molds. It will be understood that the molding composition'is of a finely porous character permeable to gases, particularly under the pressure of the metal forced into .the mold. 1

By reason of the above described improvements I am enabled to produce, in a short space of time, perfect castings or stereotypes, of a fineness and perfection of design which is only attained, so far as I am aware, by the electrotype process, and also to produce such castings within as short or shorter a time than now required for making electrotype plates. The molding compositionwhieh I employ, of which the mold is made, 1s such as to permit the same to be exposed at once to the high degree of heat required to dry it in a short time without cracking or injury to the finest detail thereof. The openwork plate or frame forming part'of the mold not only gives the rigidity and strength required, by reason of openings 3, but does not interfere with the'rapi ity of drying, and at the same time-eliminates the difliculty usuall encountered'of occluded gases and air in the molds when casting. The mold plate form:

ing a part of the mold also enables the mold to be very thin, thereby economizin'g material, as well as the time required fordrying the same 1 While I have illustrated and described a particular form of apparatus and mode of 7 operation, 'it will be understood that this is by way of illustration only, and not of limitation tot-he precise details and steps dis-. closed, since it 'will'be obvious that various modifications may be made bythose skilled inthe art, without departing from the in-' vention.

The apparatus shown'Ja-nd described but not claimed herein is claimed in my applidescribed.

cation Sen No. 487,169, filed April 1st, 1909, o fwhich the-present application is a division.

What I claim is: I y 1'. The process of forming molds which comprises arranging the patterns on asuitable base, coating said patterns with an oleaginous film, wettingsaitkfilm with'a fluid non-repellent'to water, for'the purpose suitable base, placing a flask or molding the material to set, removing said consistslin arranging thepatterns uponfla frame over said" patterns, p ourin fluid molding material into saidlflask an on the patterns, and partiall embedding or, frame in sa d mold ing' materia allowing frame and molding material and subjecting the same to heat to dry and harden,

said flask.

5. The process. of forming molds which" atterns upon a consists in arranging the sk or molding suitable base, placing a frame over said patterns, pouringfluid molding material into said flask and on the patterns,and partially embedding said flask or frame in send molding material, allowin the material to set, removin said frame" an molding material and subjecting the same to'a temperature of about 600 F. to dry andharden;

flti. The process of forming molds which consists in arranging the patterns on a suitable base, coating said patterns with a film I of oil, wetting said oil film with wood alcohol, placing a molding frameover said patterns, pouring fluid molding material-onto.

the patterns through said frafne, and "partially embedding saidframe in said molding material, allowing the mold to-set, removing the mold'irom the atterns and subjecting the same toheat to 13' and harden.

7. The process of orming molds which consists in arranging the patterns upon a suitable base, placing a flask or frame having an openwork bottom or back late over said patterns, pouring fluid mo ding material onto the patterns through saidopenwo'rk or bottom plate of the flask 5Q as to embed the same in' said molding material,

4 I allowing the material to set, removing said frame and molding-material from the .pat-

terns and subjecting the same to heatto dry 'and harden. 1 I

' JOHN J. 0. SMITH.

Witnesses:

LAURA E; Moss,

' HENRY C, WORKMAN.

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