US2391587A - Method of making molds having transition cores - Google Patents

Description

Dec. 25, l 945.

R. J. MILLER METHOD OF MAKING MOLDSV HAVING TRANSITION CORES Filed Sept. 21, 1942 3 Sheets-Sheet l IN VEN TOR. Emwa/vo J/V/u 5e BYZ-fM Dec. 25, 1945. v

R. J. MILLER METHOD OF MAKING MOLDS HAVING TRANSITION CORES I s Sheets-Sheet 5 Filed Sept. 21, 1942 INVENTOR. Pam/0N0 J/V/l. 5e

Patented Dec. 25, 1945 UNITED STATES PATEN ass st? 1 OFFICE METHOD OF MAKING MOLDS HAVING TRANSITION CODES Raymond J. Miller, Detroit, Mich auignor, by

direct and meme assignments,

Miller-Engieering Corporation, Detroit, Mich, a corpora- 11 tion oi Mic Application September 21, 1942, Serial No. 459,106

12 Claims. (Cl. 22 -131) to a pattern positioned in a desk. The moldiorming substance used in such casting opera-. tions is referably a porous or granular material or a substance like plaster susceptible or becoming porous after iormation.

In these methods or casting. production patof mold-Iorming equipment used.

lie within the usable portions or the plaster oi the cope and drag sections, since it is impossible to cast articles having a vertical dimension reater than the distance from the outside limit of the bottom of the drag to the top of the cope. This dimension consitutes a'limiting factor in the use or these casting methods because of the type In a typical die pattern a pattern has of H" is used as standard, and the vertical height of the plaster mold of the cope or drag sections is approximately 2%". In this equipment it is impossible to extend a parting into more than apterns are secured to a flask. and the combined a pattern and flask constitutes a die pattern. The external dimensions of the die patterns may be varied through relatively wide limits. However, it is desirable that the mold-forming equipment be standardized as much as possible, since dirferent flasks are required in the formation of molds of diflerent sizes, and specialized drying equipment conforming generally to the external contour of the mold-forming sections is necessary in the operation of the process.

To permit greater flexibility in the use of this equipment the die pattern may be divided into a plurality of sections of uniform size. A single pattern may extend over one or more of these sections, and patterns or diflerently shaped artifeles may be positioned adjacent each other in t flask.

proximately or the H" of the base, and it is necessary that approximately of plaster lie above the top-most portion or the pattern or the article being formed. It is thus impossible with this equipment to form a casting having a parting line extending more than approximately 3%," vertically. 7:" Of which may extend into the base.

This invention is directed to the development or an improved method whereby the vertical height or a parting may extend from the bottom limitoithe dragiothetoplimitoithecope'ina' system where disassociated patterns are employed. This may be accomplished by the use oi transition mold shaping members extending into both the cope and drag sections of the mold,

These transition mold shaping members may be formed by a reproductive process directly from the pattern 01' the article to be rormed. The "reverse side of the transition mold shaping members are contoured to eliminate back-draft, and patterns having a contour to receive the reverse side of the transition mold shaping members are formed by a reproductive process directly from Plaster molds having mold impressions of a plurality oi diil'erentarticles to be reproduced may thus be formed in the cope and drag sections of a mold. In order that the matched pattern impressions oi the 1 and drag sections oi the mold may accurately align with each other with a sufllcient degree oi accuracy to provide sood castings. the pattern segments must be accurately machined to predetermined horizontal and vertical dimensions.

Intheuseoi'presentmethods-apartinghasa vertical limit oi from the base of the pattern to the top of the cope or drag respectively, and the parting cannot extend through the base 01 the pattern.

By these methods it is also necessary that the verticaidimensionsoitheeastingtobeiormedto mold shaping members. It is thus possible to form castings wherein the parting may extend vertically throughout the entire usable moldtorming substance in both the cope and drag.

An object of this invention resides in the development of an improved method whereby the partinglinenmyextendtotheiulllimitsoithe usable portions or the mold-forming substance in both the cope and drag of molds iormed by die pattei'm.

A further object resides in the provision of an improved casting process whereby relatively deep articles may be cast in transition mold shaping members formed by a reproductive process.

Another object is to provide an improved method oi making accurately matched core-boxes and pat erns by a reproductive method thereby eliminating the ordinary laborious processesof conforming core boxes and patterns.

Still a further object of the invention resides in the provision of a novel method of making core boxes by a reproductive process to accurately embody the exact contour of the desired core in such a manner that no finishing operations are lrJequired on the core-forming surfaces of the core Another object is to provide an improved method of producing accurately aligned core and pattern members directly from a master pattern.

Other objects and advantages of this invention will be apparent from the following detailed description considered in connection with the accompanying drawings, submitted for purp ses 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:

Fig. 1 is a perspective view of a master pattern of an article requiring a parting line of greater vertical height than the combined height of a pattern base and the usable portion of one mold.

Fig. 2 is a sectional view illustrating the first step in the practice of the invention wherein the article of Fig. 1 is embedded in any suitable parting material.

Fig. 3 is a sectional view showing one step in the formation of a transition core-forming member by a reproductive process made directly from a master pattern of the article to be cast.

Fig. 4 is a sectional view, illustrating the shaping of the reverse side of the core box-forming member to a desired configuration.

Fi 5 is a sectional view illustrating the formation of a female member from which the cope production pattern is formed, the female member being formed by a casting operation from the reverse side of the transition mold shaping member.

Fig. 6 is a sectional view illustrating the formation of a companlon'transition mold shaping member.

Fig. '7 is a sectional view illustrating the shaping of the reverse side of the companion transition mold shaping member to embody a desired V shape.

Fig. 8 is a sectional view illustrating the formation of a female member from which the drag production pattern is formed, the female member being formed by a casting operation from the reverse side of the companion transition mold shaping member.

Fig. 9 is a sectional view illustrating the formation of a male production pattern from the dra female member.

Fig. 10 is a sectional view illustrating the formation of a male production pattern from the female cope member.

Fig. 11 is a sectional view illustrating the formation of the upper half of the drag core box by a reproductive method.

Fig. 12 is a sectional view illustrating the formation of the upper half of the cope core box by a reproductive method.

Figs. 13 and 14 are sectional assembly views of the drag and cope core boxes respectively.

Fig, 15 is a sectional view of the male cope production pattern being used as apart of a die pattern to form a plaster mold.

' Fig. 16 is a view similar to Fig. 15 illustrating the use of the drag production pattern to form a plaster mold conforming to the external contour Of the drag core.

Fig. 17 is a partially assembled view showing the transition mold shaping members in place.

Before explaining in detail the present invention it is to be understood 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 inven-.

tion 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.

Referring now to the drawings, Fig. l is illustrative of a pattern of any article 20 which may be formed by a casting operation. The article 20, for example, may be an angle member having a substantially flat smooth plate 22 intersected by another substantially flat smooth plate 24 at right angles thereto in such a manner as to provide an area 26 of back draft to a vertical movement of the cope section of a mold relative to the drag section thereof.

If the vertical height of a required partin such, for example, as the distance from the apex 28 to the base 30 of the article 20, and the length of both of the plates 22 and 24 are greater than the usable portion of plaster of either the cope or drag sections of a plaster mold plus the vertical height of one pattern base it would be im- Possible to use the plaster molding process by methods heretofore known in this art.

To cast the article 20 in a plaster mold it is necessary that the parting between the upper and lower mold sections extend into both the cope and drag sections. Although this has heretofore been impossible it may now be accomplished by the use of transition cores extending into both the cope and drag 'of the mold. The complications heretofore encountered in making transition cores to accurately match both the pattern of the article to be formed and the production pattern to provide the core impressions, has rendered their use impractical, if not impossible. However, by this method of forming molds, these complications may be readily overcome by the formation of matched core boxes and production patterns by a reproduction method directly from a model of the article to be reproduced.

The article 20 may be positioned on any suitable parting substance 32 such for example as molding clay, dental plaster, etc. The pattern 20 may be embedded in the substance 32 to approximately midway as illustrated by the line 34 so that a portion of the pattern 20 is above the line 34 and the remainder is below the line 34. The parting substance 32 is shaped with reference to the surfaces 22 and 24 of the article 20 in such a mannor as to eliminate back draft, as by the formation of angularly related surfaces 36 and 38. The angle of the surface 38 is such as to relieve the back draft at the portion 26 of the pattern.

Referring now to Fig. 3 it will be observed that a frame 40 is superimposed on the parting substance 32 and any suitable moldable substance 42 such for example as plaster or an alloy consisting of approximately 42% tin and 58% bismuth is ap- August 14; 1942.

asanssa the space-within the remsieiiiember u and frames I8 and 12 to form therein a male pro-- duction pattern 18 of the female member 88 of Referring now to Fig. it will be observed that a frame 50 is superimposed on the parting substance 32, and any suitable moldable substance 52 such for example as an alloy of the so-called "Cerro" type consisting for example of 42% tin and 58% bismuth is applied to the exposed surface of the transition cope mold shaping member 44 and parting substance 82 to form within the frame 80 a female member 84 conforming to the contour of the exposed portion of the transition cope mold shaping member 44.

The frame 88 is preferably formed to accurate external dimensions for use in an alignment frame consisting of a right angle to engage the side walls of superimposed frames in the subsequent formation of pattern equipment of the die attern type. I

After solidification of the substance 82 of which the female member 84 is formed, the frame 88 with the transition cope mold shaping member 44 and pattern 28 inplace therein may be inverted as illustrated in Fig. 6. The initially applied parting substance 32 may now be removed and a frame 88 superimposed on the frame 88. Any suitable moldable substance 88 such for example as plaster or cerrobend may be applied to the exposed surfaces of the pattern 28, the transverse cope mold shaping member 44 and the female member 84 within the confines of the frame 88.

The frame 58 need not accurately conform with the shape and contour of the frame 88, since all that is necessary is that it confine the substance 58 to cover the Portion of the pattern 28, formerly covered by the parting substance 82.

After the substance 88 has set, the frame 88 may be removed. The plaster or other substance 58 may then be partially cut away as illustrated in Fig. 'I to eliminate back draft and to form a transition drag mold shaping member 88 conforming to the contour of the portion of the pattern 28 formerly coveredby the parting substance 82. a

As illustrated in Fig. 8 another frame 82 of accurate external dimensions may be superimposed on the frame 88 having the female member 54 therein. The frame 82 may be accurately aligned with the frame 88 by means of a right angle frame 84. Any suitable moldable substance 88 such for example as cerrobend or cerrobase may be introduced into the space within the frame 82 to cover the exposed surface ofv the drag transition mold shaping member 88 and the edges of the cope transition mold shaping member 44 'to form in the frame 82 a female member 88 of the transition core and pattern members.

The frame 82 with the female member 88 therein may be removed, and as illustrated in Fig. 9. may be placed in the right angle frame l4. A male pattern frame 18 having accurately finished external surfaces, may be superimposed the transition drag mold shaping member 88. The frame It may be formed with an' inwardlyextended bead It to engage and securely hold the substance 14 of which the male production pattern 181s formed.

Referring now to Fig. 10 it will be observed that the frame 88 housing the female member 84 having the external contour of the cope transition mold shaping member 44, may be inverted and positioned in the right angle frame 84. A male production pattern frame 80 having accurately formed external surfaces may be superimposed on the frame 88 and aligned therewith by the right angle frame 84. A riser frame 82 corresponding to the riser frame I2 illustrated in Fig. 9 may be superimposed on the male production pattern frame 88. The space within the female member 84 and frames 88 and 82 may be filled with an suitable moldable pattern-forming substance 84 such for example as cerrobase to form a male production pattern 86 of the external surface of the cope transition core-forming member 44.

Fig. 11 illustrates the formation of the top half of the drag mold shaping core box. A frame 88 may be superimposed on the frame 82 housing the female member 68 from which the drag pattern 66 was formed. The drag transition mold shaping member 6| is positioned in the female member 68, then the members 84, 44, and the pattern 28 are removed, Any suitable moldable substance 98 such for example as cerrobase may be introduced into the spacewithin the frame 88 to form the upper half 82 of thedrag mold shaping core box.

After solidification of the substance 88 of which the upper half 92 of the drag mold shaping core box is formed, the frame 88 having the upper mold shaping core box member 82 therein isremoved from the frame 82 and the female member 68. The drag transition mold shaping member 88 may then be removed andthe elements 88 and 82 reassembled as illustrated in Fig. 13 having a mold cavity 84 accurately conforming to the contour of the transition drag mold shaping member 68 for producing the drag transition mold shaping member. A suitable opening 88 may be provided to permit the introduction of a 'mold-forming substance, such, for example, as

plaster or a gypsum compound to form' the desired drag transition mold shaping member 88 (Fig. 17) extending from the drag portion I88 of the mold into the cope portion I28.

on. the frame 82 and aligned therewith by means of the right angle frame 84. A riser frame I2 may be superimposed on the male pattern frame II and aligned therewith as illustrated. The use of the riser frame is more clearly disclosed-in my copending application Serial No. 4:54.831, filed Any suitable mold-forming substance 14 such for-example as cerrobase may be introduced Into To form the upper half of the cope mold shaping core box a frame I84 may be superimposed on the frame 58 housing the female member 84 having the imprint of the contoured surface of the cope transition mold shaping member 442 The transition mold shaping member 44 is left in place in the female member 84 and the pattern 28 is removed. Grooves I88 may be formed in the surface of the moldable substance 82 outside of the female impression 84 of the transition mold shaping member 44.

A moldable substance I08 such for example as cerrobase is then introduced into the space within the frame I84 to fill the space surround-.

ing the transition cope mold shaping member 44 and the portion of the female member 84 above the "line 34. Ridges Ill projecting into the grooves I88 are formed to accurately locate the upper half N2 of the cope mold shapingcore bus with reference to the lower half constituting the female member 04.

To form the cope mold shaping member the frame I04 housing the upper half I I2 of the cops mold shaping core box may be removed from the frame and the transition mold shaping member 44 removed from the female member I4. The upper half II2 of the cope core box may then be reassembled on the female member 54 as illus-' trated in Fig. 14 to form a cope mold shaping core mold II4 accurately conforming to the external contour Of the transition cope mold shaping member 44-.

Plaster or other suitable mold-forming substance may then be introduced into the mold shaping core box through a suitable aperture I It to form a cope transition mold shaping member II! (Fig. 17).

After the drag and cope mold shaping core box-forming members of Figs. 13 and 14 have been formed they may be assembled as illustrated therein, and any suitable mold-forming substance such for example as plaster may be introduced to formthe transition mold shaping members. After the mold shaping members have attained a substantially predetermined set in the core boxes they may be removed therefrom and subjected to a drying operation to drive of! virtuall all moisture whereupon cores of relatively porous structure having flue-grained, hard surfaces are provided to form the mold cavity I20 of the article 20 as illustrated in Fig. 1'7.

As illustrated in Figs. 15 and 16 the cope and drag production pattern members 08 and respectively are mounted on flasks I22 and I24. The patterns 08 and 16 being carried by their respective frames 80' and 10 are formed to accurate. horizontal and vertical dimensions for reception in the flasks I22 and I24.

After assembly as illustrated in Figs. and 16, mold-forming substance such for example as plaster I 26 may be applied to the die patterns composed of the combined flask and pattern members to provide cope and drag plaster molds I28 and I30 respectively'having female impressionsformed therein conforming to the shape of the contoured surfaces of the cope and drag mold shaping members H0 and 80 respectively.

As illustrated in Fig. 17 the transition drag mold shaping member 90 is assembled in the drag mold I30, and the transition cope .mold shaping member H8 is superimposed on the drag core 98. The cope mold I28 ma be placed on the transition cope mold shaping member II! and drag mold I30 to complete the mold assembly. Suitable riser and feeder chambers may be provided to supply molten alloy or metal to the cavit I formed between the mold shaping members H0 and 08 respectively.

As the alloy or metal is poured into the mold entrained air and gases formed during the pouring and cooling operations diffuse through the walls of the cpres and molds respectively to provide a solid homogeneous casting having a smooth-surface texture accurately conforming to the shape and contour of the desired article.

- The mold-forming substances employed in the various steps illustrated herein may vary through wide limits. For example, the moldable substance 32 applied in the step illustrated in Fig.2 to form a parting, may be virtually any moldable substance capable of assuming and maintaining a desired shape. The substance applied in the step illustrated in Fig. 3 to form the transition mold shaping member may be'virtually any substance, preferably possessing the characteristics 01. substantially constant volume upon solidification. It is also desirable that this substance be readily workable so that the desired contour of the transition mold shaping member mayv be readily applied thereto.

It will be apparent that if the substance employed in the various steps recited above do not possess the characteristic of constant volume upon change of state from liquid to solid suitable allowance should be made for contraction or expansion of the substance so that the resulting mold-forming members will accurately embody the desired contour.

I claim:

1. The method of making cooperating mold and mold shaping members to deflne a casting cavity comprising contouring the side of a mold shaping member opposite from the casting cavity to permit removal of the mold section in the direction of back draft, applying a moldable substance to the contoured side of the mold shaping member to provide a female impression thereof. and applying a moldable substance to the female impression to form a production die pattern thereof.

2. The method of making matched core boxes for forming mold shaping members comprising successively applying moldable substances to spaced portions of a pattern to form mold shaping members, contouring the reverse sides of the mold shaping members to permit removal of the mold shaping members in the direction of back draft, applying moldable substances to the contoured sides of the mold shaping members to produce mold shaping core-boxes, and applying moldable substances to the pattern side of the mold shaping members to provide mold shaping core boxes for the'pattern-forming sides of the mold shaping members.

3. The method of forming core boxes for forming mold shaping members comprising ap-,

lying arting material to a pattern to allow removal of a mold section in the direction of back draft, applying a moldable substance to the exposed portion of the pattern and parting material, contouring the reverse side of the applied substance to provide a mold shaping member contoured to allow removal of said member in the direction of back draft, and forming an impression of the contoured side of the mold shaping member.

4. The method of making a box for forming mold shaping members comprising applying a moldable substance to a portion of a pattern to provide a mold shaping forming member, contouring the reverse side of the mold shaping forming member, applyin a moldable substance to the contoured side of the mold shaping forming member to provide a mold shaping box portion for the contoured side, and applying a moldable substance to the mold shapin forming member to provide a mold shaping box portion for the pattern-forming side of the pattern side of the mold shaping forming member.

5. The method of making matched mold shaping and pattern members comprising applying a moldable substance to a pattern to form a parting thereon, applying a moldable substance to the exposed surface of the pattern to provide a transition mold shaping forming member, contouring the reverse side of the transition mold shaping ins member to provide a member having a female impression thereof, and forming a production die pattern from the member having said female impression to embody the contour of the contoured side of the mold shaping forming member.

6. The method of making a core box for form-- ing a mold shaping member comprising applying parting materialto a pattern to form a parting, applying a moldable substance to the exposed surface of the pattern to provide a mold shaping forming member, contouring the reverse side of the mold shaping forming member, applying a moldable substance to the contoured side of the mold shaping forming member to provide a female receptacle, inverting the assembly, remov ing the pattern, and applying a moldable substance possessing the characteristic of solidifying to the mold shaping forming member and female receptacle to form a mold shaping core box.

'7. The method of making a matched mold shaping and pattern assembly comprising applying parting material to a pattern to form a parting thereon, applying a moldable substance to the exposed surface of they pattern to provide a mold shaping forming member, contouring the side of the mold shaping forming member remote from the pattern contacting side, applying mold shaping forming member'to provide a female impression thereof, inverting the f ale impression and mold shaping forming in mber with the pattern and initially appliedparting material in place, removing the parting material, applying a moldable substance to the exposed surface of the pattern and mold shaping forming member to provide a companion mold shaping forming member, contouring the reverse side of the companion mold shaping forming member, applying a moldable substance to the contoured side of the companion mold shaping forming v member to provide a female impression thereof,

a moldable substance to the contoured side of the mold shaping forming member to provide a female member, applying a moldable substance to the female member to form a production pattern, assembling the mold shaping forming member and female member, and applying a moldable substance to the mold shaping forming member and female member to form a mold shaping-box. 8. The method of making mold shaping boxes comprising applying parting material to one of the contoured sides of a unitary pattern to form a parting thereon, applying a moldable substance to the exposed surface of the pattern and parting material to provide a transition mold shapin forming member, contouring the reverse side of the transition mold shaping forming member,- applyin a moldable substance to the contoured side of the mold shaping forming member and parting material to provide a female impression thereof, inverting the female impression and transition mold shaping forming member, removing the initially applied parting material from the pattern and transition mold shaping forming member, applying a moldable substance to the exposed surface of the pattern and transition mold shaping forming member to provide a companion mold shaping forming member, contouring the reverse side of the companion transitionmold shaping forming member, applying a moldable substance shaping forming member to provide a female imto the contoured side of the companion mold v pression thereof, separating the female impressions and their associated mold shaping forming members from the pattern, assembling theitranssition mold shaping forming members and their associated female impressions and forming mold shaping box members by applyin a moldable substance to the exposed surface ofthe transition mold shaping forming members and female reeptacles. i

9. The method of making matched mold shaping member boxes and patterns comprising applying parting material to one of the contoured.

sides of a pattern to provide a parting thereon,

applying a moldable substance to the exposed surface of the pattern to provide a mold shaping forming member, contouring the reverse side of the mold shaping forming member, applying a moldable substance to the contoured side of the separating the female impressions and their associated mold shaping forming members from the pattern, applying a moldable substance to the female impressions to form production patterns, assembling the mold shaping forming members and their associated female impressions, and forming mold shaping member boxes by applying a moldable substance tothe exposedsurface of the mold shaping forming members and female impressions. 7

10. The method of forming molds having casting cavities embodying back draft and having partings extending from the cope section into the drag section comprising embedding a unitary master pattern in parting material, contouring the parting material to allow removal of a mold shaping member from the master pattern in the direction of back draft, applying a moldable substance to the master pattern and parting material to provide a mold shaping.- member separable from the master pattern in the direction of back draft,

. contouring the exposed surface of the mold shapparting material to form an impression thereof,

forming a productive pattern member by casting a moldable substance into said impression, forming core-box members'for making mold shaping members by applying moldable substances'to opposite sides of the contoured mold shaping member, and using said production pattern and corebox members in the formation of molds.

11. The method of casting articles having a vertical height greater than theusable mold investment of a single cope or drag flask plus the usable depth of a single pattern carrying base and including back draft comprising embedding a master pattern of said article in parting material to establish a parting line intermediate cope and drag flasks, contouring the parting material to permit removal of a mold shaping member from the master pattern in the direction of the back draft, applying a moldable substance to the exposed portion of the master pattern and parting material to provide a mold shaping member surrounding the portion of the master pattern embodying back draft, contouring the exposed surface of the mold shaping member, forming a production pattern embodying the co ntoured surface of the mold shaping member, forming a producarticle in parting material to establish a parting line intermediate cope and drag flasks, applying a moldable substance to the exposed portion of the master pattern and parting material to provide a cope mold shaping member,,contouring the exposed surface of the mold shaping member,- applyin a moldable substance to the contoured surface of the mold shaping member and parting material to form a cope impression thereof, removing the parting material, applying a moldable substance to the portion of the master pattern initially contacting the parting material to provide a drag mold shaping member, contouring the exposed surface of the drag mold shaping memoms? RAYHOND J. MILLER.

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