US1882191A - Process and apparatus for casting ceramic articles - Google Patents

Description

Oct. 11, 1932. B. s. PURINTON PROCESS AND APPARATUS FOR CASTING CERAMIC ARTICLES 1931 2 Sheets-Sheet 1 Filed July 27 I C r r //I n INVENTOR Oct. 11, 1932. B. s. PURINTON 1,832,191

PROCESS AND APPARATUS FOR CASTING CERAMIC ARTICLES 2 Sheets-Sheet 2 led July 27, 1931 INVENTOR Patented Oct. 11, 1932 Lima TEN 1:0 FF! I BERNARD s aun n'rongor EAST LIVERPOOL, OHIO "rnoonss ANnArPnBATns non cAsTING CERAMIUARTICLCES 7 Application filed July 27, 1931. SerialNo. 553,28d. v

The presentinvention relates to...the casting of ceramic articles, and more especially to the casting ofceramic. articles such as chinaware, porcelain and semi-porcelain tableware, in water absorbentmoldsi In the ceramic industrytableware articles, such as pitchers,covered dishes, casseroles, and like shapes, which cannot be made on a jigger, are usually made by casting in water absorbent plaster of Paris molds. A fluid slip of ceramic. material is poured by the. workmen into the mold and allowed to stand therein until the workman judges that sufficient time has elapsed for a. semi-solidcoherent layer of the ceramic material to have become deposited against the walls of the mold due to the absorption of .the water from the slip. The workman then pours out the excess slip. The mold and its contained semis solid layer of ceramic material therein is allowedto dry. The mold is then opened and the article, such as the: pitcher or dish, is re.- moved and finished by applying the glaze and firing.

' blisters, strains, etc.

This process as carriedout in the manufacturing plant is .a hand operation, the, molds being filled and emptied by workmen. The thickness of the walls of the article is determined by the judgment of the workman in emptying the excess slip after he believes that sufficient time has elapsed for a layer. of proper thicknessto become deposited .in, themold.

The labor cost of making articles by this 51 casting method is so high that it :haisben limited to the making of those articlessuch as casseroles, covered dishes, pitchers, etc., whichcannot be-made on a rotary table or jigger. Cups, plates, and the like,'are usually. made on a rotary table: or jigg er from a bat of'plastic ceramicmaterial. The jiggering process is cheaper than" the casting process and is therefore used when possible, although the jiggeredproductis] inferior due to air The object ofmy invention is to cheapen the; cost of productionby the casting process, whereby it can be employed not only in .making articles such as pitchers, covered l sh and th l ut a so m k ng ps,

grammatically apparatus for carrying out plates, etc., which have heretofore been generally made on a jigger. I

e In carrying out my process, a water absorbent mold, such as a plaster of Paris mold, is immersed in a bath of fluid ceramic slip which rises into and fills the mold. The mold is allowed to remain in the slip bath for a pre-- determined time and is then removed, allowing theexcess slip to drain from the mold. This process readily adapts itself for machine operation, whereby the operations of dipping andremoving the molds from the slip can be carried out by machinery, thus doing away with manual labor and predetermining the time of immersion and thereby accurately controlling the thickness of the 7 layer deposited in the molds.

In-the drawings, there is illustrated diamy process. 1

In the illustrated embodiment of my inven tion, Figure l is a bottom planview of a set of plaster of Paris cup molds;-

.FigureQ is a section along the line 11-11 of.-Figurel;' a

Figure 3 is a vertical section through the molds along the line HIT of Figure lillus- "tinting the molds as immersed in the tank or S P";

Figure 4 illustrates a modification, being an interior view ofhalf of a" plate mold; and Figure 5 is a vertical sectionthrough a plate mold immersed in a bath of slip.

- Referring to the illustrated embodiment of the invention illustrated in Figures 1, 2' and 3, a number of 'cup molds l are for-med in a slab or body 2 of water absorbent material, such as plaster of Paris. The moldis used in an inverted position, as shown in the drawings. The tops of the mold cavities 1 have vent holes?) which allow the escape of entrapped air when the molds are immersed in the slip bath. In Figure 3 the molds are shown as dipped into a bath 4L of the usual ceramic slip held in a tank 5. The set-of molds is dipped, preferably by machinery, into the bath i of slip. As illustrated in Figure 3, the molds are shown as resting on a grid 6 which allows the slip to enter the mold cavities" 1.

The slip 41's the usual fluidslip,such as a is used in the hand plaster of Paris mold casting operation. It is formed by a water suspension of a mixture of clay, feldspar and flint, together with small amounts of sodaash and silicate of soda to help hold the clay mix in suspension. The slip is preparedin the usual way in a blunger and is poured into thetank 5.

.VVhen the molds l-are dipped into the bath of slip, the'slip rises and'fills the mold cavities, as shown in Figure The en-;v

trapped air escapes throughthevents 3. I

The plasterof Paris mold body, because of its water absorbent properties, absorbs the faces, and causes a-semi-solid coherent layer of the ceram1cmater1al to collect against the at the places where this is notiwished.

Water from theislip adjacentthe m'old surinnerfacesof'the molds, as indicatedatf? in Figure 3.7 The molds are allowed to remain in the bath of slip until this semi-solid coherent layer. of ceramic materialis formed to, the desired thickness for the walls of the article being" cast. Then the molds are re moved from the tank, preferably by machinery. In removing the molds, they are usually'tilted'slightly to allow the air toenter at one .side of the bottom mold cavity opene ings and the excess slip to run out andback into the bath. The molds withtheir depositedlayers of ceramic mix are then dried, pref erably in a drying room.. The drying causes a slight shrinkage of the ceramic. material,

which permits the articles,]such as the cups in the illustrated embodiment, to be readv ily removed from the molds preparatory to being finished by glazing and firing. The; spines 8 formed by the material which may enterthe vent openings 3 are readily 'cut off ofthe articles.

Since the height to the slip may rise in the vent openings 3 is. controlled byzthe depth to which the molds are dipped in the bath, there is no wasting or escaping of the slipthrough the vent holes, as would be the case in apressure casting operation.-

Asillustrated in Figures 1,2 and 3 of the drawings, the surfaces of the mold cavities l and the top surface of the plaster of Paris slip 2 areformedfromthe surface of the plaster of Paris, so that the mold cavities may absorb water and so that the water can be readily dried therefrom at the top surface of themold body as wellf'as from the mold'surfaces. The bottom surfaceeof' the mold body and the side surfaces are preferably coated or glazed with a waterproof 6 l 9 to prevent the deposit of the material This processadaptsjitself readliy to machinev operation. The molds can be dipped into the tank of slip by machinery and held therein for a predetermined time and then automatically removed, thus not only doing away with manual laborbut also substituting mechanically timed operations for the V judgment of the operator" which is now relied" upon in the manual process. The relatively large body of slip in the tank can be accu- I 'rately controlled and maintained as to condi- .of Paris The inoldpavity; 12 havin g the shape of aplate, is formed between the two. halves ofjthe split mold YA bottom feeder openingil3and; side feeder openings ltzare.

provided for admission of'the fluid slip into the mold when it is dipped into the slipibathai An air ventopeninglS is Tprovided'to allow-1 the escapeof'air trapped-in themold when it is immersed. The outer surfaces of the molds are preferably coated or glazed with a waterproof layer '16, whi'ch prevents the deposit of-the slip material at places where this is not wished; As shownin Figure 5,"the .mold is immersed in a bath 17 of fluid slip whichiby. its natural hydraulic pressure feeds itself through the feed openings 13' and 14; to sup-:1 ply the ceramic material which solidifies into asemi-solid coherent mass within the mold cavity due to the absorption of the-water from the slip by thewater absorbent plaster of'Parisl :Afterthis coherent semi-fluid body of ceramic material is formed from the slip within the mold, the mold is removed from the bathand-opened, and the bod; of the plate 18" is'allowed' "to dry' andis then removed fromthe mold ing by glazing and firing WVhile I haveillustrated scope of thefollowi g l p .e

fI'claim: 1. Theprocess of c open at its bottom, ventingthe air trapped in'the mold andfcausing theslip to-ri'seinto and fill the mold cavity and remain therein from the bath. j y a ceramic slip a water absorbent moldwhic-h is open at its bottom, rentin theyaiitrappea; in; the mold and causing the slip to riseinto preparatory to finishand described the preferred apparatus and process for carrying outfmyinvention, it is to be understood that the invention is not solimitedbut-may be otherwise embodied and practiced within the until a fsemi-SOlidcoherent lay'er' of ceramic, material is deposited against -theabsorbent} mold surfaces, 5 and then removing the {mold 125 2. The process of casting'cerainic articles, 7 Y which comprises dippinginto abath of -fluid ,j. i sting ceramic "articles; which-comprises dipping into a bath of fluid ceramie'slip a wateriabsorbent moldwhich is and fill the mold cavity and remain therein until a semi-solid coherent layer of ceramic material is deposited against the absorbent mold surfaces, raising the mold from the bath, and allowing the excess slip to drain therefrom.

3. The process of casting ceramic articles,

- which comprises dipping into a bath of fluid ceramic slip a water absorbent mold which is open at its bottom, venting the air trapped in the mold and causing the slip to rise into and fill the mold cavity and remain therein until a semi-solid coherent layer of ceramic material is deposited against the absorbent mold surfaces, raising the mold from the bath and allowing the excess slip to drain therefrom, drying the material deposited in the mold, and removing it therefrom.

&. Apparatus for casting ceramic articles, comprising a tank holding a fluid bath of ceramic slip, and a water absorbent mold adapted to be dipped into the bath having a moldcavity open at the bottom to allow the ceramic slip to rise into the mold when immersed.

5. Apparatus for casting ceramic articles, comprising a tank holding a fluid bath of ceramic slip, and a water absorbent mold adapted to be dipped into the bath having a mold cavity open at the bottom to allow the ceramic slip to rise into the mold when immersed and a vent at the top of the cavity to allow the escape of entrapped air.

In testimony whereof I have hereunto set 7 my hand.

a BERNARD S. PURINTON.

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