US3263288A

US3263288A - Method of casting cored objects

Info

Publication number: US3263288A
Application number: US331558A
Authority: US
Inventors: Schaible Michael; Tuttle Wainwright
Original assignee: Altamil Corp
Current assignee: Altamil Corp; Kennecott Corp
Priority date: 1963-12-18
Filing date: 1963-12-18
Publication date: 1966-08-02
Anticipated expiration: 1983-08-02
Also published as: SE328094B; BE657063A; DE1433936B2; DE1433936A1; GB1076627A

Description

Aug. 2, 1966 M. SCHAIBLE ETAL METHOD OF CASTING CORED OBJECTS 2 SheetsSheet 1 Filed Dec. 18, 1965 //6 Fig.1.

R D M s EE H NLL EBT m NW 0 W T T M M H H R M m MW V. 3 BM 0 0 M g- 1966 M. SCHAIBLE ETAL 3, 3,288

METHOD OF CASTING CORED OBJECTS Filed Dec. 18, 1963 2 Sheets-Sheet 2 INVENTOR. MICHAEL SCHAIBLE AND WAINWRILJHTTUTTLE,

ATTORNEYS.

United States Patent 3,263,238 METHOD fil CASTING EURED OBJECTS Michael tichaihle, Indianapolis, Ind, and Wainwright Tattle, Cincinnati, Uhio, assignors, by mesne assignments, to Altamil Corporation, Indianapoiis, Ind, a corporation of Delaware Filed Dec. 18, 1963, Ser. No. 331,558 9 Claims. (Cl. 22194) This invention relates to a method for making and finishing metallic castings, and more particularly to a process in which the patterns and resulting mold cavities, and corebox cavities and resulting cores are oriented in a particular manner to obtain certain advantages.

The teachings of this application may advantageously and desirably be employed in conjunction with the methods and apparatus taught in ec-pending applications Ser. 263,156, now US. Letters Patent No. 3,181,213, dated May 6, 1965, entitled, Method for the Use of Dynamic Vacuum in Foundry Operations, Ser. 179,960, now US. Letters Patent No. 3,181,207, dated May 6, 1965 entitled Automatic Mold Preparing Apparatus, and Ser. 239,945,

now U.S. Letters Patent No. 3,216,071, entitled, Method and Apparatus for Producing Molds, all filed in the names of Schaible et a1.

By way of background, a conventional casting process may be outlined as follows: Mating mold halves (generally a cope and a drag) are formed over a suitable pattern to provide a mold cavity which conforms to the outside configuration of the end product desired. If the casting is to be hollow, a core which conforms to the inside configuration of the end product must then be made from a suitable material, and placed inside the cavity formed by the mating mold parts, and supported therein by one or more core prints. The casting metal is then poured into the assembled mold and allowed to harden, whereupon the mold is parted, the product removed and the core knocked out of its center. The casting is at this point ready for final cleaning, machining, or other finishing operations.

Broadly considered, this invention consists of the orientation of the cavities defined between the corebox halves, and/or the mold cavities between the mating mold parts, in such a way that at least one axis of the cavity is perpendicular to the parting surface between the corebox halves and/ or mold box parts respectively. In spite of its apparent simplicity, this invention is of very great commercial significance. It is believed that the following list of objects and advantages of this invention will facilitate a complete understanding of the invention and its ramifications:

(1) Many more individual elements can be cast in a mold of a given size. This results in higher productivity and lower costs because the cost of molding materials, labor, and overhead is thereby reduced for each casting.

(2) Cores may be formed by introducing sand or other moldable material into a corebox cavity in a split corebox through an opening in one of the corebox halves, this opening being actually the end of the corebox cavity. This eliminates the need for separate blow holes, and the consequent problems of blow hole wear and cleaning.

(3) Furthermore, the above openings for the introduction of moldable material may be disposed at the end of each of the corebox cavities, even in the case of multiple rows of cavities, where the cavities in the inner rows are inaccessible from the side of the corebox.

(4) A superior core results in part because the sand or other moldable material flows more readily in the direction of introduction, and does not have to change direction as much as is necessary with a conventional orientation.

(5) The novel orientation of core cavities as taught 3,263,283 Patented August 2, 1.966

by this invention also greatly facilitates the automatic ejection of cores from one of the corebox halves, by permitting the application of force to the end of the core. The cores will then remain embedded in and projecting from the other of the corebox halves for transporting and automatic core setting. As set forth in more detail hereinafter, this core ejection may be accomplished with relatively low pressures which will prevent overstressing the core box, and eliminates the need for punching out sand from blowholes in the corebox, or the use of complicated and inefficient projecting blow tubes.

(6) In the case of cored castings, orienting the mold cavity so that at least one axis is perpendicular to the parting surface between the mold parts, will insure that at least one of the mold halves includes one full core print and a half core print. This permits individual cores to be set in mold cavities with short core prints, in such a manner that the core is balanced and will not shift or sag out of position prior to mold closing.

(7) The novel orientation taught by this application also permits the solidified castings to receive additional operations, such as cleaning, core knock out, machining, and tinning while they are still secured to the gates and runners. This means that all the castings gated to a single runner may be handled at once, and that the various operations listed above can be carried out automatically because all the ends of each casting are readily accessible to the Working tools without interference, as set forth in more detail hereinafter.

With specific reference to the co-pending applications referred to earlier in this specification, it is a further object of this invention to provide an improved method of positioning mold cavities and cores which will permit the pattern draw (or mold extraction), core ejection, core setting, and mold closing motions to be in the same direction, e.g. vertical.

Referring to the drawings:

FIGURE 1 is a top plan view of a drag mold for cast brass solder T fittings, the mold cavities being oriented according to the teachings of this invention;

FIGURE 2 is a sectional elevation of mating cope and drag molds for the same product;

FIGURE 3 is a sectional elevation of the mating corebox halves utilized to produce cores for the above product, the cavities being oriented according to the teachings of this invention, and showing a plurality of cores remaining partially embedded in and projecting from one of the corebox halves;

FIGURE 4 is a sectional elevation showing a plurality of cores being set in the cavities of the drag mold;

FIGURE 5 is a top plan view of a drag mold for solder T fittings, the mold cavities being oriented according to conventional practice;

FIGURE 6 is a sectional elevation of a mating cope and drag showing conventional mold cavity orientation;

FIGURE 7 is a perspective view of a plurality of castings still attached to one of the runners by the gate;

FIGURE 8 is a sectional elevation of a portion of an assembled mold showing the manner of parting a elbow to carry out the method of this invention; and

FIGURE 9 is a sectional elevation of a portion of an assembled mold showing the manner of parting a 45 elbow to carry out the method of this invention.

While it will be understood that the invention is applicable to the casting of a wide variety of products, such as pipe and tube fittings, electrical fittings, and plumbing fittings, it will be described in detail with respect to a specific product; namely, a cast brass T fitting adapted to be sweat soldered to copper tubing. As seen in FIGURES 1 and 2, the mold cavities for the T fitting are oriented with the longest axis or straight run 10 of the T oriented perpendicular to the parting surface between the cope 11 and the drag 12. In the case of casting a T fitting, the parting surface between the mold parts is substantially planar; however, as set forth in connection with a modification of this invention, the mold parts in certain cases mate along a surface which is non-planar, In this latter case, the parting surface between the mold halves will be characterized by two or more parallel planar surfaces, and it will be understood that the phrase parting surface as used hereinafter in this specification is to be construed as including both the planar and non-planar embodirnents.

It will be seen that each of the mold cavities for a T fitting includes the

core prints

13, 14, and 15a and 15b,

the

core prints

13 and 14 being at the upper and lower ends respectively of the cross piece 10 of the T, while the

portions

15a and 15b together constitute a core print at the end of the leg 16 of the T.

This novel orientation of the mold cavities may be compared with the conventional orientation shown in FIGURES and 6. In this case, it will be seen that the cross piece 20 of the T as well as the leg 26 (corresponding respectively to the cross piece and leg 16 of the T of FIGURES 1 and 2) are both parallel to the parting surface between the mold halves.

When oriented in the conventional manner, it will be seen that the cope and drag molds each contain three half-core prints, 23a, 24a, and 25a, and 23b, 24b, and 25b respectively. By way of comparison, when the mold cavities are oriented according to applicants teachings, each core is set in one complete core print and one halfcore print, while in the conventional process, a core is set in three half-core prints. Applicants have found that their unique orientation greatly facilitates automatic handling and setting of cores, and in the case of setting individual cores for a 90 or 45 elbow as described later in this application, applicants orientation becomes essential.

It will also be apparent from comparing FIGURES 1 and 5, that by virtue of applicants orientation, one is able to cast 24 solder T fittings in a single mold of a given size, whereas when utilizing the ordinary and -con ventional orientation, it is only possible to cast 12 such fittings in a single mold of the same size.

Turning now to FIGURE 3, cores for the above described T fittings are formed between a pair of

mating corebox halves

30 and 31. Once again, it will be seen that the core cavities are oriented so that the longest axis or cross-piece 32 of the core is perpendicular to the parting surface between the corebox halves. While a plan view of the corebox has not been shown, it will be understood that the cavities between the corebox halves are arranged on the same dimensional layout as the cavities between the mold parts, as will be made clear hereinafter.

When the

corebox halves

30 and 31 are held tightly together, sand or other moldable material is introduced through the apertures 33 in the top of the corebox half 30. It will be apparent that each of the apertures 33 is actually an open end of the longest axis of one of the corebox cavities. This arrangement means that the core box need not be provided with separate blowholes, thereby eliminating many problems of the prior art, such as blowhole wear, and the need for cleaning sand out of the blowholes, or the need for complicated and inefiicient projecting blow tubes. This further means that a core formed in such a corebox will be free from unwanted blowhole projections on its body which would cause an indentation or weakening of the wall of the ultimate casting if not cleaned off in a separate operation.

As set forth in greater detail in US. Letters Patent 3,181,207 and 3,181,213 referred to earlier in this specification, handling and setting of the cores automatically is greatly facilitated by ejecting the hardened cores from one of the corebox parts, so that they remain partially embedded in and projecting from the other corebox part. Preferably, these cores may be ejected from the half 30 of the corebox by applying force to the exposed end of the core itself, through the same aperture 33 through which the moldable material was introduced. As noted earlier in this specification, the apertures 33 are relatively large, and make it possible to use the resilient diaphragm described in detail in United States Letters Patent 3,181,207 and low pressures which will not overstress the corebox. That is, the diaphragm may bear against the entire exposed end of the core for ejection, rather than force itself through a small blowhole.

Referring again to FIGURE 3, it will be understood that the core box halves 30 and 31 are held tightly together while sand or other moldable material is introduced through the apertures 33 in the core box top 30. After the cores 32 have been hardened in any conventional manner, an ejecting force, preferably by means of the diaphragm (not shown) briefly described above will be applied to the exposed end of the core through the aperture 33. At the same time, the core box halves 30 and 31 will be separated, bringing them to the positions shown in FIGURE 3. By virtue of the application of force through the openings 33, and the simultaneous separation of the core box halves, the cores will remain partially embedded in and projecting from the core box bottom 31.

The ejected cores which are now partially embedded in and projecting from core box bottom 31 may be set in the cavities in the drag 12 as briefly described above and shown in FIGURE 4, the core being supported in the complete core print 14 and the half core print 15b.

Referring now to FIGURES 8 and 9, the special problems of orienting and parting a elbow fitting and a 45 elbow fitting will be described. FIGURE 8 illustrates a cope 40 and drag 41 mating along the parallel

planar surfaces

42 and 44, these surfaces being joined by the curved portions 43. It will be apparent to the skilled worker in the art that when a fitting such as the 90 elbow illustrated is oriented in the manner described above, namely with at least one axis perpendicular to the parting surface, it will be impossible to provide a planar parting surface which does not require an undercut cavity. That is, the planar portion 42 bisects a leg 45 of the fitting being cast. If the parting line 42 of the leg 45, when viewed as in FIGURE 8, is lowered, the cavity in the cope 40 will be undercut. Similarly, if the planar portion 44 is raised to a position coplanar with the portion 42, the drag cavity will be undercut by virtue of the curved portion 46 of the elbow.

According to conventional practice, when casting a 90 elbow fitting, the mold cavity is oriented so that the axes of both legs of the elbow are parallel to the parting plane between the mold surfaces. This permits utilization of a planar parting surface, but presents numerous other difliculties. It will be readily apparent to the skilled worker in the art that if the mold cavity is oriented with both axes parallel to the parting surface between the mold halves, each mold part will include two half core prints, and an elbow core cannot be supported horizontally in the two half core prints unless they are made extremely large, thereby further reducing the capacity of the mold. To avoid this difliculty, the prior art would generally arrange two or four elbow fittings so that the passages through the fittings define generally a U or an 0 respectively, in which cases a single U-shaped or O shaped core respectively can be used to core two or four elbows. Either of these arrangements further reduces the capacity of the mold.

By virtue of this invention, the mold cavity defined between a pair of mating mold halves is oriented so that one of the mold halves (in this case the drag 41) ineludes at least one complete core print (in this case the core print 48). As will now be readily understood, a core for the 90 elbow fitting may be set in the drag 41, wherein it is set in one complete core print 48, and

in one-half of the core print 47. When so set, the core Will be balanced and accurately held in position, with only a short core print and will not sag or shift position during a subsequent mold closing operation.

It will immediately be apparent to the skilled worker in the art, that in this embodiment the novel orientation of the mold cavity taught in this application permits an even greater increase in the number of fittings which can be cast in a given mold. It will also be apparent that this orientation is readily adaptable to a fully automatic core setting operation, such as is set forth in applicants co-pending applications referred to earlier. Still other advantages of this arrangement will be set forth hereinafter.

FIGURE 9 is in many respects similar to FIGURE 8, except that it shows the arrangement for orienting a elbow figure. In this case, the cavity between the cope and the drag 51 is oriented so that the drag contains one complete core print, 52, and a portion of the core print 53. The parting surface between the cope 50 and drag 51 is defined by the parallel planar portions 54 and 56, these portions being joined by the angular and curved portions SSaand 55b.

It will probably occur to the skilled worker in the art that orienting a screw fitting with an enlarged, threaded end as taught herein will involve an undercut mold cavity. In this case, it will be necessary to employ novel pattern construction taught in applicants co-pending application Serial No. 239,945, entitled Method and Apparatus for Producing Molds.

As explained earlier in this application, the term parting surface is intended to be comprehensive of both the truly planar parting surface defined between the cope and drag set up as shown in FIGURES 1 through 4, as well as the non-planar surfaces illustrated by way of example in FIGURES 8 and 9. It may again be noted at this time that the non-planar parting surfaces of FIG- URES 8 and 9 may be characterized as including a series of parallel, planar portions joined by variously configured intermediate portions, and the phrase oriented perpendicular to refers in this case to the parallel, planar portions.

For automatic operation, the corebox cavity is preferably oriented with respect to the parting surface between the corebox parts in the same relative position that the mold cavity is oriented with respect to the parting surface between the mold parts. In other words, the separation of the corebox halves will involve the same direction of motion with respect to the product as the core setting and mold closing motions.

As noted at the outset of this specification, one of the advantages of this invention is to provide a novel orientation of the mold cavity, whereby further operations such as cleaning, core knockout machining, and tinning of the finished casting may be carried out while the castings are still secured to the runners by means of gates. For convenience, these various further operations will generically be called finishing. Referring at this time to FIGURE 7, a number of solder T fittings and 90 elbows 61 are joined by the gates 62 to the runner 63. It will be seen that at least one axis of each fitting is perpendicular to the runner, by virtue of its original orientation perpendicular to the parting surface between the mold halves. It will also be noted that each of these fittings include a second axis intersecting the first axis, the second axis also being perpendicular to the runner 63. By virtue of this arrangement, it is believed apparent that each of the ends of each casting is readily accessible to appropriate machine heads, without interference due to other castings. Similarly, the castings may be cleaned and cores may be removed by shot blasting, since this orientation permits direct impingement of the shot on all exterior and interior surfaces.

The fact that each end of each casting may be reached for cleaning and machining without interference from other castings means that all of the castings gated to a single runner may be handled and chucked at once, for a substantially automatic finishing process.

It is believed that the foregoing constitutes a full and complete disclosure of the invention, through an exemplary embodiment illustrating many of its most important ramifications. Numerous modifications within the scope and spirit of this invention will readily occur to the skilled worker in the art, and hence no limitations are intended except insofar as set forth in the following claims.

What is claimed as new, and what it is desired to secure by Letters Patent is:

1. In a method of casting cored objects having intersecting axes including the steps of forming a pair of mold halves mating along a parting surface and defining at least one cavity therebetween, said cavity having at least two complete core prints; the improvement which comprises orienting said mold cavity within said mold halves so that one of said mold halves includes at least one complete core print and at least a portion of another core print of said cavity.

2. The process claimed in claim 1 including the steps of forming a core and setting said core in said one mold half having at least one complete core print.

3. The process claimed in claim 2 wherein said step of forming a core is accomplished by providing a two part corebox mating along a parting surface and defining a core cavity therebetween, orienting said core cavity so that at least one axis of said cavity is perpendicular to said parting plane, filling said cavity with moldable material, to form a core, and ejecting said core from one of said corebox halves, said core remaining embedded in and projecting from the other of said corebox halves, whereby the portion of said core projecting from said other of said corebox halves may be set in said one mold half.

4. In a method of casting cored objects having intersecting axes including the steps of forming a pair of mold halves mating along a parting surface and defining at least one cavity therebetween, said cavity having at least two complete core prints; the improvement which comprises orientating said cavity so that at least one axis of said cavity is perpendicular to said parting surface, whereby one of said mold halves includes at least one complete core print and at least a portion of another core print of said cavity.

5. In a casting process for producing objects having at least two intersecting axes including the steps of forming a plurality of mold cavities joined by gates to a runner between a pair of mold halves mating along a parting surface, forming a plurality of cores and setting said cores in said cavities; the improvement which comprises the step of orienting said cavities so that at least one axis of each cavity is perpendicular to said parting surface, said axis also being perpendicular to said runner, and orienting said cavity so that a second axis of said cavity is oriented perpendicular to said runner.

6. The process claimed in claim 5 wherein said second axis is generally parallel to said parting surface.

7. In a process for making hollow castings wherein a plurality of mold cavities, at least one of said cavities having intersecting axes, are formed between a pair of mold parts mating along a parting surface, said cavities being joined by gates to a runner, and wherein a plurality of cores are formed and set in said mold cavities; the improved process comprising the steps of:

(a) orienting said plurality of mold cavities so that at least one axis of each said cavity is perpendicular to the parting surface between said mold parts, said axes also being perpendicular to said runner, said intersecting axes of said cavity also being oriented perpendicular to said runner;

(b) setting said cores in said cavities; and

(c) filling said cored cavities, gates, and runner with molten metal to form a plurality of castings gated to a runner, whereby each of said plurality of castings may be machined while remaining gated to said runner.

8. The process claimed in claim 7 wherein said second axis is parallel to said parting surface.

9. In a process for making hollow castings having intersecting axes wherein a plurality of mold cavities joined by gates to a runner are formed between a pair of mold parts mating along a parting surface, and wherein a plurality of cores are formed in cavities between a pair of corebox halves mating along a parting surface, said cores being set simultaneously in said mold cavities; the improved process comprising the steps of:

' (a) orienting said plurality of mold cavities so that at least one axis of each said cavity is perpendicular to the parting surface between said mold parts;

(b) orienting said core cavities so that at least one axis of each cavity is perpendicular to said parting sur face, said parting surface of said mold cavities and said parting surface of said core cavities each dividing the respective cavities in the same relative position;

(c) filling said core cavities with moldable material to form a plurality of cores;

(d) ejecting said cores from one of said corebox halves, said cores remaining embedded in and projecting from the other of said corebox halves; and (e) setting said cores in said mold cavities.

References Cited by the Examiner UNITED STATES PATENTS 393,349 11/1888 Ayres 22-433 433,588 8/1890 Adams 22130 506,227 10/1893 Hammer 22--10 506,228 10/1893 Hammer 22-10 1,365,029 1/1921 Fisher 22-111 2,209,502 7/1940 Annich 22-130 15 2,831,225 4/1958 Kolbe et a1 22198 2,899,725 8/1959 Zink et a1 2210 2,940,142 6/1960 Wells et al. 22130 3,060,534 10/ 1962 Enzenbacher 22193 3,096,547 7/ 1963 Hunter et al 22-10 3,179,990 4/1965 Freeman 22194 J. SPENCER OVERHOLSER, Primary Examiner.

MARCUS U. LYONS, Examiner.

25 E. MAR, Assistant Examiner.

Claims

1. IN A METHOD OF CASTING CORED OBJECTS HAVING INTERSECTING AXES INCLUDINGG THE STEPS OF FORMING A PAIR OF MOLD HALVES MATING ALONG A PARTING SURFACE AND DEFINING AT LEAST ONE CAVITY THEREBETWEEN, SAID CAVITY HAVING AT LEAST TWO COMPLETE CORE PRINTS; THE IMPROVEMENT WHICH COMPRISES ORIENTING SAID MOLD CAVITY WITHIN SAID MOLD HALVES SO THAT ONE OF SAID MOLD HAVLES INCLUDES AT LEAST ONE COMPLETE CORE PRINT AND AT LEAST A PORTION OF ANOTHER CORE PRINT OF SAID CAVITY.