US2394394A

US2394394A - Pattern having integral ventforming members

Info

Publication number: US2394394A
Application number: US472719A
Authority: US
Inventors: Raymond J Miller
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-01-18
Filing date: 1943-01-18
Publication date: 1946-02-05
Anticipated expiration: 1963-02-05

Description

Feb. 5, 1946. R, J M L R 2,394,394

PATTERN HAVING INTEGRAL VENT-FORMINGMEMBERS Filed Jan. 18, 1943 s Sheets-Sheet 1 //6 INVENTOR.

,, 2 P4r/v0/vo KM/use 2 BY :v gin M4 Feb. 5, 1946. R. J. MILLER 2,394,394

I PATTERN HAVING INTEGRAL VENT-FORMING MEMBERS Filed Jan. 18, 1945 3 Shets-Sheet 2- INV EN TOR.

Patented Feb. 5, 1946 umrso STATES PATENT orrics PATTERN nlavmc m'rncnu. vnu'romumc MEMBERS Raymond J. Miller, Detroit, Mich. Application January 18, 1943, Serial No. 472,719

16 Claims.

This invention relates to the art of casting, and more particularly to the production of molds formed of plastic or granular substances such as plaster having venting runners or openings formed therein in an improved manner to permit the ready escape of entrained air or gases created during the casting operation.

Fine grained substances such as plaster of Paris or gypsum for use as mold-forming substances have been considered for a long time. Difflculties have been experienced in venting molds formed of such fine grained substances because of the virtual impossibility of forming venting runners or openings to permit the ready escape of entrained air and gases formed when molten alloy or metal is introduced into the casting cavity.

In the Capaco process of plaster molding as described in Patent No. 2,210,037, issued May 14, 1940, relatively porous molds are formed to permit the dissipation of entrained air and gases through the walls of the mold-forming substance. No venting passages are employed in such molds, and the only communication between the casting cavity and the atmosphere other than through the walls of the mold-forming substance is through the gate and sprue provided to admit molten alloy to the casting cavity.

In the Capaco process porosity of the moldforming substance is achieved by adding excess water to gypsum powder reinforced by asbestos fibre. The excess water is dispelled by a drying or curing operation to leave voids or open spaces in the portions of the mold formerly occupied by the water. If too large a quantity of water is employed, the mold will be too weak to withstand the pouring stresses to which it is subjected when molten alloy is introduced into its cavity to form a casting. If too small a quantity of water is employed, the resulting mold does not possess sufilcient porosity to enable the entrained air and gases to escape with a sufficient degree of rapidity. In molds having the highest possible permeability consistent with providing the necessary strength to withstand the pouring stresses, the molten alloy must be introduced quite slowly to enable the entrained air and gases to diiiuse through the walls of the mold. The molten alloy frequently chills and solidifies before the casting cavities are completely filled, whereupon inferior castings result.

Diflicult problems are also encountered in maintaining the gypsum powder suspended in the liquid until the mold has attained a predetermined set to provide a homogeneous mold. Elaborate air and gases formed during the casting operation may be readily dispelled from the casting cavity.

An object of this invention resides in the formation of cooperating patterns having a parting extended to the top of the pattern to provide a venting passage in the cope section of molds formed from the patterns.

Another object is to provide an improved method of forming molds having integrallyiormed venting passages.

A further object of the invention is to provide molds having venting passages leading from portions of the casting cavities positioned so that they would become isolated as molten alloy or metal is poured into a mold to form a casting.

An additional object resides in the formation of a novel and improved method of venting molds whereby the isolation of casting cavity sections during the pouring of the mold is prevented.

Another object is to provide improved venting means for a mold formed from a plurality of die patterns positioned in a flask wherein vent pas= sage-forming bars carried by each die pattern communicate with a venting outlet associated with the flash.

Yet a further object of the invention is to pro-- vide an improved method of venting die patterniormed molds of gypsum material whereby more durable molds having greater density capable of producing castings having smoother surface texture may be formed.

Still another object resides in the formation of cooperating cope and drag molds having improved venting means formed by extending the parting line to a point adjacent the upper extremity of the casting cavity in the cope mold.

An additional object of this invention is to provide production pattern equipment formed by a reproductive process and having vent passageforming members carried thereby.

A further object resides in the formation of gypsum molds having feeding passages communi cating with the lowermost portions of the casting cavities to minimize turbulence resulting from the introduction of molten alloy or metal to form castings.

Yet another object of the invention resides in the formation of pattern-carrying blocks having impression-forming runner members to permit feeding of molten alloy or metal adjacent the bottom of a, casting cavity and to permit the escape of entrained airand gases from the top of the casting cavity.

Another object is to provide an improved method of venting casting cavities by means of venting passages extending through various sections of the mold and capable of being successively isolated as molten alloy or metal reaches them. without interrupting the venting action of other por tions of the venting system. 3

Other objects and advantagesof this invention will be apparent from the following detailed description considered in connection with the accompanying drawings, submitted for purposes of illustration only and not intended to define the scope of the invention, reference being had for that purpose to the subjoined claims.

In the drawings wherein similar reference characters refer to similar parts throughout the several views: a

Fig. 1 is a fragmentary'plan-view of a flask containing a plurality of die patterns embodying the present invention.

Fig. 2 is a fragmentary sectional view taken substantially on the line 22 of Fig. 1 looking in the direction of the arrows.

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 1 looking in the direction of the arrows.

Fig. 4 is a sectional view taken substantially on the line 4-4 of Fig. 1 looking in the direction of the arrows.

Fig. 5 is a view similar to Fig. 1 showing a modified form vof the invention.

Fig. 6 is a sectional view taken substantially on the line 6-8 of Fig. 5 looking in the direction of the arrows.

Fig. '7 is a fragmentary sectional view of a portion of a mold member.

Fig. 8 is a view similar to Fig. 7 showing the step of perforating the upper portion of the mold to vent the casting cavity.

Fig. 9 is a fragmentary sectional view of a vent riser positioned in the mold body.

Fig. 10 is a view similar to Fig. 6 showing a modified form of the invention. i

Fig. 11 is a fragmentary sectional view taken substantially on the line I l-ll of Fig. 10 looking in the direction of the arrows.

Fig. 12 is a sectional view taken substantially on the line l2-I2 of Fig. 11 looking in the direction of the arrows. v

Fig. 13 is a side elevational view or a ventforming member adapted to be positioned on the flask to form a vent in the mold.

Fig. 14 is a fragmentary sectional view of'a mold embodying a vented outlet formed by the member illustrated in Fig. 13.

Fig. 15 is a fragmentary side elevational view of a pattern embodying a modified type of ventforming member.

Fig. 16 is a fragmentary sectional view illustrating a mold formed from the pattern and vent members illustrated in Fig. 15.

. Fig. 17 is a side elevational view of a pattern embodying a modified form of venting means.

Fig. 18 is a sectional view taken substantially on the line l8-l8 of Fig. 17 looking in the direction of the arrows.

Fig. 19 is a fragmentary sectional view taken substantially on the line l9-l9 of Fig. 1'! look--' ing in the direction of the arrows.

Fig. 20 is a view similar to Fig. 19 showing a still further modified form of venting means.

Fig. 21 is a fragmentary sectional view illuse.

trating the cope and drag mold members embodying the venting feature disclosed in Figs. 17 to 19.

Fig. 22 is a sectional view illustrating a still further modified form of the invention.

Fig. 23 is a fragmentary sectional view of assembled cope and'drag molds illustrating a plurality of vent passages interconnecting spaced casting cavities with a single main vent passage. Fig. 24 is a-fragmentary sectional view taken substantially on the section line 2424 of Fig. 25

of the assembled cope and drag molds formed from pattern equipment of the type illustrated in Fig. 1 wherein the cope casting cavity is formed from the pattern impression 36 of Fig. 1 and illustrating the venting of portions of the casting cavity projecting to diflerent vertical heights above the parting line between the cope and drag molds.

Fig. 25 is a fragmentary plan view of the casting cavity of the cope mold, taken substantially on the line 2525 of Fig. 24 looking in the direction of the arrows.

Before explaining in detail the present in, vention it is to be vunderstood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed'herein is for the purpose of description and not of limitation.

While this invention is applicable to all types of pattern equipment and the molds formed therefrom, it is illustrated herein as applied to molds and pattern of the so-called die pattern type wherein a plurality of pattem-carrying blocks l0, l2, 14, etc., are removably-mounted in a flask Hi. .The pattem-carrying blocks l0, l2, l4, etc., are carried by frames i8, 20, 22-, etc. detachably connected to the bottom plate 24 of the flask It by means of screws 26. -A separator member 28 preferably extending transversely of the flask It may be provided to divide the space within the flask into two separated pattem-receivin compartments.

A feeder-forming runner 30 may be positioned on the separator member 28 to forma feeder impression 3| in the .cope mold 33 to conduct molten alloy or metal from the space formed in the mold by a feeder-forming member 32 to the casting cavities 35 formed in the mold investment by the

pattern impressions

34, 36, etc., carried by the blocks l0, I2, etc., respectively.

The feeder-forming runner 30 connects with riser-forming members associated with each of pressions by way of controlled feeder-forming.

members such as the impressions 50'and 52 carried by the pattern blocks ill and i2 respectively.

The frames i8, 20, 22, etc., are formed to accurate external dimensions in three planes and are of graduated sizes so that a pattern-carrying frame of proper size may be selected to accommodate a particular pattern. The space within the flask it may thus be emciently used, since a plurality of patterns of the same or difierent sizes may be used simultaneously to form cope or drag molds havin casting cavities conforming to the contours of the venous patterns employed.

Die patterns are of the so-called separated pattern-plate type and are used in pairs in the formation of cope and drag molds cooperating to provide the desired casting cavities. The cope and drag pattern members of each pair of cooperating pattern blocks are accurately positinned with reference to the edges of their assoelated pattern-carrying frames, and since the frames are accurately positioned in the flask it, assurance is bad that the pattern impressions in the cope and drag molds will accurately align to form thedesired casting cavity.

iihe production pattern equipment on the pat tern-carrying block it, it, id, et cetera, may be formed by the reproductive method as disclosed in my copending applications Serial No. 421,115, filed December 1, 1941 (M47), and Serial No. 454,831, filed August 1 1942 (M-ZB). This production pattern equipment may be formed from separated complementary master pattern members or from a unitary master pattern formed of wood or of any other suitable material.

Where a unitary master pattern is employed, it may be embedded in any suitable parting ma terial, such for example as molding clay, wax, plaster of Paris, paramn, etc, up to its normal parting plane to divide the pattern into vertically-spe/ced sections having no back draft. The parting material may be contoured adjacent the edge of the pattern to extend the parting to the top of the cope pattern to accommodate the venting runners employed to permit the escape of entrained air and gases from the casting-cavity. The parting material may also be contoured to drop the parting down to the bottom of the casting cavity to permit the feeding of alloy or metal at the bottom or the casting cavity to prevent turbulence in the flow of the metal when pouring the mold. The parting line need not be straight, but must be continuous around the periphery of the model.

A female impression of the exposed portion of the pattern and the surface of the parting material may be formed in a frame in any suitable moldable substance, such for example as alloys of the bismuth antimony base including cerrobase possessing the characteristic of flowing and solidifying with negligible change of volume. The assembly may then be inverted, the parting me.- t'erial removed, and another female impression formed in the same type of material of the then exposed portion of the pattern and the exposed surface of the female impression formerly made. These complementary female impressions may be separated, the pattern removed, and the female impressions used in the formation of production patterns.

Where the pattern equipment is being reproduced from separated pattern segments, female impressions of each segment may be formed in suitable frames, and the production pattern equipment formed from these female impressions.

Where so-called match-plate patterns are desired, the female impressions of vertically-spaced portions of the desired pattern may be positioned on opposite sides of a pattem-carrying frame and till suitable moldable substance introduced into the space within .the frame and the female impressions to form a matched-plate pattern having the desired complementary pattern impressions on opposite sides of a single plate as more clearly illustrated in my copending application Serial No.

465,234, filed November 11, 1942 (M-33).

Where separated patterns of the die pattern type are to be formed, the pattern-carrying frames it, it, 22, etc., may be superimposed on and aligned with frames of the same dimensions having the female impressions of the desired pattern. The production patterns may then be formed by introducing into the space within the frames a moldable substance capable of filling the female impression and the space within the pattern-carrying frames it, 28, 22, etc. Many types of substances are suitable for forming the production pattern equipment, such for example as white metal, alloys of aluminum, the bismuth antimony base alloys such for example as cerrobase, cerrobend, and cerromatrix, etc. If the substance of which the female impressions and the production patterns are formed do not possess the characteristic of substantially constant volume upon solidification, suitable allowance should be made to compensate for the variation.

Great flexibility and accuracy are involved in the formation of pattern equipment by the reproductive process, and in view of the facility with which the parting may be-extended vertically, it is possible to achieve results not heretofore practical.

Referring now to Figures 1 to 4, the pattern 36 on the pattern-carrying block it is a cope pattern of a connecting rod having a central body portion at having spaced rigidifying webs 5t and 58 and large and small end connections til and 62.

In the formation of the pattern 3% the master model corresponding with the contour of the pat-. tern 35 is embedded in the parting material, and the parting material is applied to the edges of the model to provide tapered or angularly-disposed sections 6 3 and 66 adjacent the large and small ends 60 and tirespectively. Venting strips t8 and it are formed on the tapered sections 6d and lid respectively and preferably extend to the end of the block it remote from the feeder.

The venting strips 68 and, it may be reproduced from any convenient, preferably pliable substance applied directly to the parting material before the female impression is formed. The

tapered sections 64 and 66 extend the parting to the top of the high sections of the pattern and are tapered angularly as illustrated to facilitate separation of the pattern from the female impression during'the formation of the pattern equipment, and the separation of the mold from the pattern when molds are formed.

The venting strips 68 and In communicate preferably at the end of pattern-carrying block id with eventing strip l2 extending transversely feeder runner-30 is disposed angularly to lead the molten substance down through thesurge poolis ber 38 communicating with the casting cavity through the controlled feeder-forming member 88. As illustrated in Figs. 23 to 25 the

vents

91, 99 and IM being positioned adjacent the top of the high portions of the casting cavities of molds formed from the pattern remain open to permit I the escape of air and gases until the casting cavity is completely filled, and the shrinkage compensating supply of molten alloy or.metal in the riser chamber formed by the riser-forming member 88 maintains the casting cavity completely filled until solidification is complete The pattern 88 carried by the block I2 is illustrative of an irregularly shaped article having a plurality of

portions

88, 82, 84 and 86 projecting above the surface of other portions of the pattern. These vertically extended portions of the

pattern form impressions

8i, 83, 85, etc., in the mold having no venting communication one with the other, or with the outside atmosphere during the pouring of molten alloy or metal into the mold when the alloy or metal rises above the surface of the mold cavity adjacent the vertically extended

impressions

8i, 83, 85, etc., of the

portions

88, 82, 84 and 88 of the pattern. As illustrated, these high portions ofthe casting cavity of'themold formed from the pattern 38 may be readily vented by providing

tapered sections

88, 98, 92 and 94 adjacent each of the vertically extended

portions

88, 82, 84 and 88 respectively. The

tapered sections

88, 98, 92, etc., form impressions 88. 9|, 93, etc., in the cope mold 33 formed from the cope pattern 38 as illustrated in Fig. 25. .Vent forming runner strips 98, 98 and I88 communicating with the topmost portions of the vertically extended

portions

88, 82 and 84 of the pattern may communicate with a single vent forming runner strip I82 extending longitudinally of the pattern carrying block I2. The vent forming runner strips 98, 98- and I88

form vent runners

91, 99 and IN extending along the tapered

impressions

89, 9| and 93 respectively of the casting cavity of the cope mold 33, and these branch vent passages communicate with a single 'vent passage I83 communicating with a main vent passage I8'I extending along the end of the mold as illustrated in Figs. 24 and 25. A vent forming runner I84 extends to the top of the' tapered section 94 positioned adjacent the porcasting cavities extend down the contoured part9 ing to the normal parting linev 285 between the cope and drag molds. All 01' the vent passages 288, 28'! and 288 communicate with a single vent passage 289 extending along the parting line between the cope and drag sections of the mold to a main vent passage 2I8 extending across the end of the mold and communicating with atmosphere.

Figures 5 and 6 illustrate a somewhat modified form of the invention wherein a venting strip 8 is carried by the flask I8 along the marginal edges of the pattern block 18, I2, I4, etc. The

longitudinally-extended venting strips 88 and I8 of the pattern block I8 and the longitudinallyextended strip I82 and I84 of the block I2 abut against the end of the transversely-extended strip II8 carried by the flask I8 to form the impressions of the vent system in the mold formed from the die patternsand flask. The vent riserforming member I4 is preferably positioned at the opposite end of the flask I6 from the feederforming member 32.

After the pattern blocks have been formed in the manner indicated aboveand are assembled in the flask I8, themold investment may be introduced into the flask to form the mold. Where plaster of Paris or gypsum is used as the mold investment, it is necessary only to add a suflicient quantity of liquid to chemically combine with the gypsum powder because the improved venting means permits the ready escape of entrained air and gases formed during the pouring operation.

The flask I8 is filled with the mold investment to a desired point above the highest portion of the pattern and riser members. After the mold has attained a predetermined set as by the use of a heating or curing operation, the patternis extracted and the cope and drag molds are assembled for use in the formation of castings. The formation of the cope pattern only has been illustrated; however, it will be understood that the drag pattern will be complementary thereto tion 88 of the pattern to form-an impression of a vent runner in the mold to vent the portion of the mold formed therefrom. The longitudinally extended vent runners I82 and I84 communicate with a transversely extended vent runner I88 carried bythe pattern block I2 and aligned with the transversely extended vent runner I2 carried by the pattern block I8 to form a main vent runner I8I in the mold to permit the escape of entrained air and gases through the venting opening formed by the vent riser I4.

It will be understood that the parting line 31 between the cope mold 33 and the drag mold 39 is contoured so that the drag mold 39 carries projections to close the tapered

impressions

89, 9|, 93, etc., and leave the

vent passages

91, 99 and IN, etc., open to permit entrained air and gases to escape from the casting cavity when the mold is filled to form a casting.

'Fig. 23 illustrates cope and drag molds 288 and 2! having a plurality of spaced casting cavities 282, 283 and 284 wherein the parting line 285 casting cavities corresponding with the contour of the pattern.

In the formation of the drag pattern equipment, the runner members applied to the parting material to form the vent passages are removed before the drag female impression is formed of the master model and parting material. The female impression from which the drag pattern equipment is formed thus embodies the contour of the parting material applied to extend the parting to the top of the cope pattern, but does not have the impressions of the venting runners. When molds are formed from the cope and drag pattern equipment, the impressions of the venting runners remain open to permit the ready escape of entrained air and gases formed during the pouring of the castings.

Figure 7 illustrates a fragmentary section of the cope mold I I2 having an impression I I4 of the vent riser I4. It will be noted that the mold closes over the top of the impression H4. The impression H4 is opened to atmosphere as illustrated in Figure 8 by projecting any suitable tool through the impression II4 to form the opening II8 to permit entrained air and gases to escape from the casting cavities through the venting network formed in the mold. It Will be apparent that the vent-forming riser may extend through the top of the mold, if desired.

A vent riser may be positioned in the mold II 2 to permit increasing the hydrostatic casting pressure, if desired. Fig. 9 illustrates a vent riser ltd having a tapered lower edge I22 adapted to be introduced into the mold H2 above the impression 6 i d of the vent-forming member.

If desired, means may be provided to maintain each venting member open until its associated casting cavity is completely filled and prevent interruption of the main venting passages when a single vent positioned at a low level is closed.

as illustrated in Figures 10 to 12, a recessiorming member are may be positioned on the pattern-carrying block in alignment with the longitudinally-extending vent-forming member iii. When the mold investment is introduced into the desk to form the mold, it conforms to the shape of the recess-for member 528 and embodies an enlarged recess in alignment with the venting passage l8.

ii. filter member, such for example as a synterized block 928 may be introduced into the recess iSil as illustrated in Figure 12. The block 21223 is relatively porous and permits entrained air and gases to flow through it readily. When the casting cavity is completely filled, molten alloy or metal flows through the venting passage 532 formed the mold H2. When the molten alloy or metal contacts the synterized block i 28 it congeals because the porosity of the block is not sufficient to permit the alloy or metal to pass through. The individual venting passage is thus closed; and the main transversely-extending venting passage is not interrupted, but is maintained open to permit free venting of other portions of the casting cavity. It will be apparent that filter members or interrupting blocks can be positioned in branch-venting conduits, if desired, as between the longitudinally-extending venting conduits m2 and the branch conduits provided to vent the portions of the mold formed by the vertically-extended

portions

80, 82, and 84 of the pattern 36.

The main vent riser preferably carried by the flask it may be closed after the casting cavity is completely filled to permit increasing the hydrostatic pressure without using a riser member as illustrated in Fig. 9. The vent riser ll of Fig. 13 may be contoured, such for example as to provide a cylindrically-shaped portion I36 to form a seat for a :iilter member in the form of a synterized plug M8 as illustrated in Fig. 14. When the casting cavity has been completely filled and the need for venting eliminated, molten alloy or metal flowing down the main venting passage formed by the vent-forming strip i6 contacts the synterized disc and congeals, whereupon the hydrostatic pressure may be increased, because the molten alloy or metal cannot escape through the venting riser.

lhe mold impressions formed from individual sections of the pattern may be conveniently vented by means of individual vents, if desired.

As illustrated in Figure 15, a vent-forming memher it? may be positioned on any portion of the pattern to vent the casting cavity formed therefrom. The vent-forming member 562 is preferably provided with a. contoured portion M4 to provide a seat for a filter member such as a synterized disc M8 in the mold H2 as illustrated in Figure 16. The disk 8 is preferably of a. thickness equal to the depth of the cylindrical portion idd to provide the mold H2 with a casting cavity with a smooth-textured surface accurately aligned with the remainder of the casting cavity.

When the mold has been formed with a vent impression M8 conforming with the contour oi the vent-forming member 2, the top of the mold may be broken out as indicated at iii! to mrmit the escape of entrained air and gases through the synterized disc. When'the casting cavity is filled, the molten alloy or metal contacts the synterized disc E46 and stops. The synterized disc being fine-grained provides the vented portion of the casting with a smooth-textured surface.

The entire mold may be formed of synterized material, if desired, by introducing any suitable metal powder in the flask to conform to the shape of the pattern. The metal powder may then be synterized to bond it together to embody the contour of the pattern. Desirable substances for this purpose are synterized iron, brass, copper, bronze, etc. These synterized molds have a vem high permeability and permit the ready escape of entrained air and gases without any venting means. Smooth-textured castings may be formed, because the synterized material has a fine-grained, smooth surface. It is possible to cast ferrous metals .of virtually all types in synterized molds, because of the high melting point of the substances available for use in the for:- mation of synterized molds. These molds are quite strong and do not distort after being synterized, and are fully capable of withstanding the stresses to which they are subjected.

Figures 1'1 to 21 illustrate a further modified form of the invention to prevent the venting system from becoming prematurely rendered inoperative where portions of the casting cavity to be vented are disposed at varying vertical heights.

The pattern to is provided with a vent-carrying member 552 adjacent each high portion of the pattern where venting of the casting cavity of the mold would be required. The vent-carrying member 852 communicates with the portion of the pattern where venting is required by means of a web or rib i156. A vent-forming strip 55d extends up the side of the vent-carrying member i52 across its top and down the opposite side to connect with a vent-forming strip I58 on the pattern-carrying block.

Where a pattern has a plurality of sections of varying vertical height used in the formation of molds having impressions extending above the adjacent surface of the mold and capable of beoming isolated as molten alloy or metal is introduced into the casting cavity, vent-carrying members 852 of a vertical height greater than the highest point of the pattern may be provided adjacent each portion of the pattern where venting is desired. The vent system is not interrupted when the lowest vented portion of the casting cavity is filled, because the remainder of the vent passages remain open until the entire casting cavity of the mold is filled. This result is accomplished because the vent-carrying members lot are higher than any portion of the casting cavity.

It is of course only necessary to provide the venting system on the cope pattern. The web or rib l54 is slightly tapered as illustrated in Figure 18 to eliminate back draft. The vent-carrying member l52, web H54, and vent-forming strip I55 may be applied to the master model from which the pattern equipment is formed. The shape and contour of these venting members are reproduced in the female impression from which the" production pattern equipment is formed by the reproductive method.

When the cope production pattern equipment has been iormed and positioned in the flask, mold-iormingsubstance may be applied to form the cope portion of the mold. After the mold has been separated from the pattern, a plug I80 preferably formed of the same or similar material of which the mold is formed may be inserted into the hole formed by the vent-carrying member I52. The plug I60 fills the impression of the member I 52, but leaves open the vent passage I 62 formed in the mold by the vent-forming strip I56.

No provision need be made on the drag pattern for this venting system, because the plugs I80 inserted into the mold impressions of the ventcarrying members I62 confine the venting arrangement to the cope mold.

After the cope and drag molds I85 and I88 have been assembled as illustrated in Figure 21, molten alloy or metal may be introduced into the casting cavity I68 to form the desired casting. The casting I68 will have a rib or web I'Ifl conforming to the shape of the web or rib I54 carried by the pattern. This rib I Hi may be removed in any desired manner as by cutting or grinding,

whereupon the casting will be ready for use.

As illustrated in Figure 20, the vent-forming strips I56 may be disposed at less than 180 relative to each other on the vent-carrying member I52, if necessary, because 01' space limitations.

Figure 22 illustrates an embodiment of the invention wherein a filtering plug I12 is inserted in a contoured aperture -I'M in the mold body II 2. The aperture may be formed by a suitable former similar to that illustrated in Figure 13. The filtering plug I12 may be used repeatedly, since it does not deteriorate with use.

If the molten alloy or metal contacting the lower end of the plug shows a tendency to seal or close the pores of the synterized plug, the end of the plug may be sandblasted or .machined slightly on a grinding wheel or any other suitable machine to recondition the plug for use. The plug may be used over and over again until it is worn down to substantially wafer thickness.

I claim:

1. A casting mold comprising .cope and drag mold bodies cooperating to form a plurality of separate casting cavities having vertically extended portions having no venting communication one with the other when molten alloy or metal is introduced into the mold to form castings, abranch vent communicating with the top of each of said vertically extended portions and extending along the parting line between the cope and drag molds, a' main vent interconnecting said branch vents with atmosphere, and means to interrupt the flow of molten alloy or metal through said branch vents to the main vent.

2. A mold having a casting cavity including a plurality of sections of diilerent vertical height having no venting communication one with the other when molten alloy or metal is introduced into the casting cavity, vent passages communicating with the top of said sections of difierent vertical height, and a main vent passage interconnecting said vent passages with atmosphere, said vent passages being extended vertically to points adjacent the highest of said sections of difierent vertical height to prevent molten material from entering the main vent passage until the casting cavity is completely filled.

3. A-mold comprising cope and drag members cooperating to form acasting cavity having a plurality of sections of different vertical height,

2,894,894 e and vent passages communicating with the top of each of said sections of diflerent vertical height and extending. along the parting line between'the cope and drag members of the mold.

4. A mold comprising cope and drag members cooperating to form a plurality of separate and independent casting cavities of difierent vertical height, and vent passages communicating with the top 01' each of said sections of dlfl'erent vertical height and extending along the parting line between the cope and drag members of the mold to vent each of the separate and independent casting cavities.

5. A mold comprising cope and drag members having a casting cavity including a plurality of sections of different vertical height having no venting communication one with another when molten alloy or metal is introduced into the casting cavity, branch vent passages communicating with the top of each of said sections of difierent vertical height and extending along th parting line between the cope and drag members of the mold, and a main vent passage extending alon the parting line between the cope and drag members of. the mold and connecting a plurality of the branch vent passages with atmosphere.

6. A mold comprising cope and drag sections having a casting cavity including a plurality of sections of difierent vertical height having no venting communication one with another when molten alloy or metal is introduced into the casting cavity, branch vent passages extending from the top of each of said sections of diflerent vertical height interposed between the cope and drag sections of the mold, a main vent passage interconnecting a plurality of the branch vent passages, and check valve means between a plurality of the branch vent passages and the main vent passage to prevent molten alloy or metal from flowing into the main vent passage until the castlng cavity is completely filled.

7. Production pattern equipment comprising cooperating drag and cope patterns having a plurality of spaced sections of diflerent vertical height on the cope pattern, vent forming runners contacting the top of each of said sections of diflerent vertical height and extending along the parting line between the drag and cope patterns.

8. Production pattern equipment comprising cooperating drag and cope patterns wherein the cope pattern has a plurality of spaced sections of diiferent vertical height, the drag and cope patterns being contoured to extend the parting line forming runner contacting the top of the pattern impression and extending down the tapered section and along the surface of the plate to the marginal edge of the plate.

10. A production pattern comprising a base, a

. pattern impression projecting above the base, a

vent forming runner contacting the top of the pattern impression and extending adjacent the pattern impression to the base and thence along the base.

11. A mold .formlng flask comprising a bottom plate, a frame surrounding the bottom plate,

a plurality of pattern carrying blocks detachably secured to the bottom plate, said pattern carrying blocks having a substantially fiat base and a pattern projecting above the base to form a casting cavity in the mold, the blocks being contoured adjacent the patterns to extend the parting line of the mold to a point adjacent the top of each pattern, and a vent forming runner contacting the top of each pattern and extending along the contoured portion of the block and along the substantially flat base to the edge of each pattern carrying block.

12. The method of making production pattern equipment comprising mounting a master pattern having portions of different vertical height on a substantially fiat surface, applying parting material adjacent the portions or different vertical height to provide tapered sections extending from the top of said pattern portions to the substantially flat surface, applying a vent forming strip to contact the portions of the pattern of different vertical height and extend down said tapered sections and along the substantially fiat surface, applying a mold forming substance to form an impression of the pattern and parting material and vent forming strip, and casting production pattern equipment in said impression.

13. The method of making cooperating cope and drag production pattern equipment comprising applying parting material to a unitary pattern to eliminate back draft and establish a parting line between cope and drag molds, applying parting material to the pattern to extend the parting line between the cope and drag molds to points adjacent the top of the pattern, applying vent forming strips to contact the top of the pattern and extend along the parting material, applying mold forming substance to form an impression of the desired cope pattern and parting material and vent forming strip, forming cope production pattern equipment in said impression by a casting operation, forming another impression of the pattern and parting material, removing the parting material, applying mold forming substance to form an impression of the desired drag portion of the pattern formerly covered by the parting material. removing the pattern, and forming drag production pattern equipmaterial to the master model to extend the parting to the top, of the pattern, applying a ventforming strip to the parting material, forming a cope impression of the model and parting material with the vent-forming strip in place, removing the vent-forming strip from the parting material, forming another impression of the pattern and parting material, removing the parting material, forming a drag impression of the model in said another impression with the parting material removed, and forming cope and drag patterns from the cope and drag impressions.

15. A mold comprising cope and drag sections having a generally horizontally disposed parting when assembled in the casting position and cooperating to form a casting cavity extending into the cope section, the parting between the cope and drag sections being contoured adjacent the casting cavity extending into the cope section to extend to a point adjacent the top of the casting cavity, and a vent passage communicating with the top of the casting cavity and extending along the parting line between the cope and drag sections to permit the escape of air from the casting cavity.

16. The method of making cooperating cope and drag production pattern equipment having vent-forming strips from cooperating cope and drag patterns without vent-forming strip comprising applying parting material to the cope pattern to extend the parting to the top of the cope '-pattern impression, applying a vent-forming strip to the parting material, forming a cope impression of the cope pattern and parting ma,- terial with the vent-forming strip in place, con touring the drag pattern in conformity with the parting material applied to the cope pattern with the vent-forming strip removed, forming a drag impression of the contoured drag pattern, and forming cope and drag production patterns from the cope and drag impressions.

RAYMOND J. MIILER.