Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3863706 A
Publication typeGrant
Publication dateFeb 4, 1975
Filing dateDec 4, 1972
Priority dateDec 4, 1972
Publication numberUS 3863706 A, US 3863706A, US-A-3863706, US3863706 A, US3863706A
InventorsChandley George D, Lamb John N
Original AssigneeHitchiner Manufacturing Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Metal casting
US 3863706 A
Abstract
Apparatus, methods and molds for casting metal in an evacuated-inert gas atmosphere. The apparatus comprises a sealable melting and mold pouring chamber having a sealable loading compartment mounted thereon with a conduit having a valve communicating therebetween and a sealable mold container having a bottom opening for sealing around the lower open end of a gas permeable refractory shell mold sealingly supported therewithin and extending downwardly therebeyond. Power means supports the container from above for movement between the chamber and compartment through the conduit to a melting crucible within the chamber directly beneath the container. The mold is loaded and unloaded with the container in raised position within the compartment while maintaining the chamber in evacuated condition by closure of the valve. A movable drip guard is mounted within the loading compartment between the valve and the container in its raised position. The refractory, gas permeable, shell mold preferred has a lower open end with a central vertical riser passage and may have a plurality of overlapping mold cavities clustered thereabout connected to the riser passage by gate passages. The cross section area dimension of the riser passage is at least one inch and five times as great as the cross section area dimension of a gate passage, so that molten metal can be drained from the riser passage to provide discrete unconnected cast parts from a single mold after the mold is separated from them.
Images(5)
Previous page
Next page
Description  (OCR text may contain errors)

United States Patent 1191 Chandley et a1.

1 1 Feb. 4, 1975 METAL CASTING [75] Inventors: George D. Chandley; John N. Lamb,

both of Amherst, NH.

{73] Assignee: Hitchiner Manuiacturing C0,, lnc.,

Milford, NH.

[22} Filed: Dec. 4, 1972 [21] App]. No.: 312,138

[52] US. Cl 164/255, 164/256, 164/306, 164/363, 164/62, 164/66, 164/63, 249/120 [51] Int. Cl 822d 27/16 [58] Field of Search 164/306, 309, 61, 62, 257, 164/262, 77, 63, 65,119, 63, 361,129, 363.

Primary Examiner- Francis S. Husar Assistant Examiner-V. K. Rising [57] ABSTRACT Apparatus, methods and molds for casting metal in an evacuated-inert gas atmosphere. The apparatus comprises a sealable melting and mold pouring chamber having a scalable loading compartment mounted thereon with a conduit having a valve communicating therebetween and a scalable mold container having a bottom opening for sealing around the lower open end of a gas permeable refractory shell mold sealingly supported therewithin and extending downwardly therebeyond. Power means supports the container from above for movement between the chamber and compartment through the conduit to a melting crucible within the chamber directly beneath the container. The mold is loaded and unloaded with the container in raised position within the compartment while maintaining the chamber in evacuated condition by closure of the valve. A movable drip guard is mounted within the loading compartment between the valve and the container in its raised position. The refractory, gas permeable, shell mold preferred has a lower open end with a central vertical riser passage and may have a plurality of overlapping mold cavities clustered thereabout connected to the riser passage by gate passages. The cross section area dimension of the riser passage is at least one inch and five times as great as the cross section area dimension of a gate passage, so that molten metal can be drained from the riser passage to provide discrete unconnected cast parts from a single mold after the mold is separated from them.

6 Claims, 9 Drawing Figures WAG Q WIIIIIIJ SHEEI 2 OF 5 'III III [FIG.

PATENTED sum 30F 5 1 METAL CASTING This invention relates to metal casting apparatus, methods and molds and more particularly to the casting of metal in an evacuatedinsert gas atmosphere and the casting of a plurality of discrete unconnected parts in a single mold.

The precision casting on a high production basis of metals which must be cast in an evacuated or inert gas atmosphc re has long been a problem. In part, this is due to the time necessary to establish the required seals and to evacuate the apparatus. especially insofar as the relatively large melting and pouring chamber is concerned. There are also problems caused by the inclusion in the cast parts of dross or other impurities present on the surface of the molten metal. Additionally there are problems in separating the cast parts from the solid metal riser connecting them, which make necessary relatively wide separation between the mold cavities.

Accordingly, it is a major object of the invention to provide much improved apparatus, methods and molds for casting metal in an evacuated-inert gas atmosphere and one capable of operating in much reduced cycle times.

It is another object of the invention to provide a dross and impurity free molten metal surface for introduction into the mold.

It is still another object of the invention to provide novel methods and molds which provide automatic separation of the cast parts from one another and so make possible greatly increased part packing within the mold.

This is accomplished, according to one aspect of the invention, by providing, preferably in combination with a scalable melting and mold pouring chamber having a scalable loading compartment mounted thereon and valve and conduit means communicating therebetween, that improvement which consists of a scalable mold container having a bottom opening for sealing around the lower open end of a gas permeable mold supported therewithin and extending downwardly therebeyond and power means supporting the container from above for movement between the chamber and compartment through the valve and conduit means. Preferably, the mold container has independent upper and lower relatively movable cup elements supported by suitable fluid actuated pistons for vertical movement. A melting crucible for holding molten metal is mounted within the chamber directly beneath the container. Means are provided for selectively varying the pressure of the chamber, compartment and container to fill the mold after lowering the container with the lower open end of the mold beneath the surface of molten metal in the crucible. The mold is loaded and unloaded with the container in raised position within the loading compartment while maintaining the chamber in evacuated condition by closure of the valve means. A movable drip guard may be mounted within the loading compartment between the valve and conduit means and the mold container in its raised position.

In another aspect, the invention provides dross and impurity free molten metal by inductive stirring in the crucible to cause outward surface movement to carry impurities away from the central area of the crucible to which the mold opening is introduced.

The invention, in still another aspect, provides a novel mold and method of casting in a refractory, gas permeable, shell mold comprising providing a mold having a lower open end with a central vertical riser passage having a plurality of preferably overlapping mold cavities clustered thereabout and connected to the riser passage by gate passages. The cross section area dimension of the riser passage is at least about 1 inch and five times as great as the cross section area dimension of a gate passage, so that molten metal can be drained from the riser passage after solidification in the mold cavities to provide discrete unconnected cast parts from a single mold after the mold is separated from them.

For the purpose of more fully explaining the above and further objects and features of the invention, reference is now made to the following detailed description of preferred embodiments thereof, taken together with the accompanying drawings, wherein:

FIG. I is a side view, partly broken away and in section, illustrating apparatus according to the invention;

FIGS. 2 and 3 are, respectively, detail side and top sectional views of a gas permeable shell mold of the invention mounted in the apparatus of FIG. 1;

FIGS. 4 through 6 are sectional side views of the operating elements of the apparatus of FIG. 1 showing successive steps in the operation of the methods of the invention;

FIGS. 7 and 8 are, respectively, detail side and top sectional views of another gas permeable shell mold of the invention such as may be mounted in the apparatus of FIG. 1; and

FIG. 9 is an isometric view of a cast part from the mold of FIGS. 7 and 8.

Referring to the drawings, and especially to FIG. 1 thereof, there is provided a scalable melting and pouring chamber 12 with a sealable loading compartment 14 mounted thereabove having a door 15. A conduit 16 having a slide valve 18 provides selective communication therebetween.

In chamber I2 is provided a melting crucible 20 having surrounding induction coils 24 which form part of an induction melting furnace 22. Furnace 22 is mounted on vertically movable platform 26 by means of interposed load cells 30 to permit the measuring of the weight of furnace 22 and hence that of the molten metal in crucible 20. Platform 26 is moved vertically by hydraulic cylinder and piston 32 mounted on support plate 34. Chamber 12 may be provided with a bottom closure 36 mounted on support plate 34, and the latter may be mounted on dolly 38 by scissors legs 41 for removal of furnace 22 from chamber 12.

More specifically as to the present invention, within chamber 12 and compartment 14 is mounted a scalable mold container, generally designated 40, having a bottom opening 42 including an annular seal 44 for sealing around the lower open end 46 of a gas permeable mold, generally designated 48, supported therewithin and extending downwardly therebeyond (FIG. 2). Mold 48 is of the precision refractory, gas permeable, shell type utilizing the lost-wax" technique and is well known and widely used in the art for casting a wide variety of ferrous and non-ferrous metals and alloys, such as steel. aluminum and nickel'chromium alloys, for example.

As shown in FIGS. 2 and 3, the novel mold of the invention includes, connected to its open end 42, a central vertical riser passage 50 with a plurality of mold cavities 52 clustered thereabout and connected to riser passage 50 by gate passages 54, the transverse cross section area dimension of the riser passage, as seen in FIGS. 3 and 8, for example. being at least about one square inch and preferably no greater than about 10 square inches in cross section area dimension and at least about five times as great as the transverse cross section area dimension of a gate passage, as seen in FIGS. 2 and 7, for example. Mold 49, shown in FIGS. 7 and 8, is similar in its construction and dimensional relationships to mold 48. It includes a central riser passage SI and a plurality of longitudinally and circumferentially spaced gate passages 55 connecting the riser passage to a plurality of mold cavities circumferentially clustered thereabout, both in longitudinally and transversely radially overlapping relationship with regard to riser passage SI. ln FIGS. 7 and 8, the mold spaces are shown as containing separated discrete cast parts 90 with short gate stubs 92 (FIG. 9) in accordance with the methods of the invention as hereinafter more fully explained.

Mold container 40, as best shown in FIGS. 4 through 6. includes a lower cup element 56 with bottom opening 42 and seal 44 (FIG. 2) and an upper cup element 58 with a gas communicating pipe 60. Each of said elements is independently supported from above for movement into sealing relationship with one another and for bodily vertical movement directly between an upper position within loading compartment 14 through conduit 16 to a lower position in chamber 12 with the lower end 46 of mold 48 beneath the central area of the surface 62 of molten metal in crucible 20. To this end, upper cup element 58 is suspended by piston rod 64 of central hydraulic cylinder 66 centrally mounted on the upper end of container 14 and lower cup element 56 is suspended by side piston rods 68, 70, respectively, of hydraulic cylinders 72, 74 mounted on the upper end of container 14 at the sides of central hydraulic cylinder 66. Hydraulic cylinders 66, 72 and 74 are operated in the conventional manner to provide power for moving piston rods 64, 68 and 70 as required.

A pair of pans 76, 78 forming a movable drip guard are mounted within loading compartment 14 above conduit I6 and are moved between their open and closed positions as shown in FIGS. 1, 4, 5 and 6 by suitable air cylinders (not shown).

Suitable vacuum pumps (not shown) are provided for evacuating loading container 40 through pipe 60, mold compartment 14 through pipe 80 and chamber 12 through pipe 82. A supply of inert gas, such as argon, is provided in bottle 86 for controlling the vacuum pressure in container 40 through pipe 60, chamber 12 through valve 88 and loading compartment 14 through valve 89 as desired.

In operation, with door 15 of loading compartment 14 and slide valve 18 open, and with lower container element 56 raised, crucible 20 may be charged by passing ingots directly through open drip guard doors 76, 78. Alternatively, cup element 56 may be removed and suitable tongs or the like may be used for carrying ingots to crucible 20 by downward movement of piston rods 68, 70. Slide valve 18 is then closed and chamber 12 evacuated through pipe 82 to a suitable high vacuum (about microns) at which time the ingots may be melted by supplying power to induction coils 24.

After melting is completed, according to another aspect of the invention, the induction coils 24 surrounding crucible 20 holding the molten metal operate to stir it by moving it axially of coils 24 upwardly in the center of the crucible to cause outward surface movement to carry dross and other impurities away from the central 5 area of crucible 20.

A molding cycle may be begun with the apparatus positioned as shown in FIG. 1. That is, with container cup elements 56, 58 separated, a mold 48 is placed in bottom opening 42 of bottom cup element 56 with its 0 open end 46 therebelow (FIG. 2). Door of loading compartment 14 is then closed, and the upper element 58 of container 40 moved downwardly into sealing relationship with its lower element 56 (FIG. 5). Container 40 and compartment 14 are then evacuated through pipes 60 and 80 to a high vacuum of about 10 microns. Then container 40, compartment I4 and chamber 12 are backfilled with argon to a suitable low vacuum (about 25 inches Hg).

After all three are at the same vacuum pressure, according to the methods of the invention, as shown in FIG. 6, slide valve 18 is opened and sealed container 40 lowered by piston rods 64, 68 and 70 past open drip guard doors 76, 78 until its open end 46 is below the surface 62 of the dross and impurity free molten metal in the central area of crucible 20. Lower cup element 56 is kept above the surface 62. The molten metal is then caused to enter vertically positioned mold 48 by lowering the pressure in container 40.

According to another important aspect of the invention, after the metal has solidified in mold cavities 52 and in at least part of their gate passages 54, the still molten metal in riser passage 50, preferably while open end 46 is kept below the molten surface 62, is caused to drain back by gravity flow into the molten supply of metal in crucible by raising the pressure in container 40 by admitting argon through pipe 60. Thus, before open end 46 is moved above surface 62, the only metal left in the mold (FIG. 7) except near its open end 46, are the desired solidified cast parts 90 with short gate stubs 92 (FIG. 9) which it will be noted do not extend for the full length of the gate passages 55.

After molding is completed, container 40 is raised into compartment 14, drip doors 76, 78 are closed, and slide valve 18 is then closed. Thereafter, compartment 14 is raised to atmospheric pressure, its door IS opened, container cup elements 56, 58 separated and mold 48 or 49 removed to complete the molding cycle. The mold 48 or 49 is then separated from the contained parts by conventional methods, providing a plurality of discrete, unconnected parts (FIG. 9).

This aspect of the invention can perhaps best be understood in connection with FIGS. 7 and 8 in which the cast parts (FIG. 9) are shown as present in the mold in the form of a plurality of discrete, unconnected parts 90 with short gate stubs 92, as is made possible by the dimensional relationships of the central riser and gate passages as set forth above. The elimination of the solid metal riser which in heretofore conventional practice connected all the parts together makes possible uniquely high density packing of the mold cavities to the extent that it would be impossible as a practical matter to separate the parts were they connected to a solid metal central riser. Such is the case with the mold of FIGS. 7 and 8, which illustrates the actual practice of the invention in the casting of golf iron heads (FIG.

When it is desired to replenish the supply of metal in crucible 20, such may be done while maintaining the pressure in chamber 12 by placing an ingot in an appropriate pair of tongs in place of lower container element 56, evacuating and pressurizing compartment 14 with argon, opening slide valve 18 and lowering the ingot into crucible 20 by piston rods 68, 70.

What is claimed is:

I. In casting apparatus having a sealable melting and mold pouring chamber,

a scalable loading compartment mounted on said chamber and valve and conduit means communicating between said chamber and said compartment that improvement comprising:

a scalable mold container having a bottom opening for sealing around the lower open end of a gas permeable mold supported therewithin and extending downwardly therebeyond said mold container including upper and lower cup elements movable into sealed relationship with one another a crucible in said chamber having surrounding induction coils for holding and stirring molten metal to cause outward surface movement thereof along its surface to carry impurities away from the central area of said crucible power means including piston means independently supporting said cup elements from above for relative movement into said sealed relationship and for movement between said compartment and said chamber through said valve and conduit means to said central area of said crucible and means for selectively varying the pressure of said chamber, compartment and container to fill said mold after lowering said container with the lower open of said mold beneath the surface of molten metal in said central area of said crucible and permit loading and unloading said mold from said container in raised position by relative movement of said cup elements within said compartment while maintaining the chamber pressure by closure of said valve and conduit means.

2. Casting apparatus as claimed in claim 1 further comprising a movable drip guard mounted within said loading compartment between said valve and conduit means and said cup elements in raised and separated position.

3. ln casting apparatus having a sealable melting and mold pouring chamber,

a sealable loading compartment mounted on said chamber and valve and conduit means communicating between said chamber and said compartment that improvement comprising:

a sealable mold container having a bottom opening for sealing around the lower open end of a gas permeable mold supported therewithin and extending downwardly therebeyond said mold container including upper and lower cup elements movable into sealed relationship with one another power means for supporting said elements for relative movement into said sealed relationship and for moving said container between said chamber and said compartment through said valve and conduit means a melting crucible for holding molten metal mounted within said chamber beneath said container and means for selectively varying the pressure of said chamber, compartment and container to fill said mold after lowering said container with the lower open end of said mold beneath the surface of molten metal in said crucible and to permit loading and unloading said mold from said container in raised position within said compartment while maintaining the chamber pressure by closure of said valve and conduit means.

4. Casting apparatus as claimed in claim 3 further comprising a movable drip guard mounted within said loading compartment between said valve and conduit means and said container in raised position.

5. Casting apparatus as claimed in claim 3 wherein said power means are fluid piston means independently supporting said cup elements.

6. Casting apparatus comprising a melting crucible having surrounding induction coils for holding molten metal a scalable mold container having a bottom opening for sealing around the lower open end of a gas permeable mold supported therewithin and extending downwardly therebeyond, said mold container including upper and lower cup elements movable into sealed relationship with one another power means including piston means independently supporting said cup elements from above for relative movement into said sealed relationship and for movement towards said crucible to lower the open end of said mold beneath the surface of molten metal in said crucible and means for relatively varying the pressure within said container to fill said mold after lowering said container with the lower open of said mold beneath the surface of molten metal in said central area of said crucible and permit loading and unloading said mold from said container in raised position by relative movement of said cup elements.

a a t a

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1703739 *Aug 8, 1924Feb 26, 1929Wilhelm KlepschMethod of casting with the aid of gaseous pressure mediums
US1834101 *Mar 22, 1930Dec 1, 1931Aurora Metal Company IncCasting apparatus
US2379401 *Apr 16, 1942Jun 26, 1945American Steel FoundriesMethod and apparatus for casting metal
US2756138 *Apr 28, 1944Jul 24, 1956Meister GeorgeProcess of vacuum refining uranium
US3410332 *Jun 7, 1965Nov 12, 1968Amsted Ind IncMethod and apparatus for casting metals in a controlled atmosphere
US3589199 *Feb 19, 1970Jun 29, 1971Aluminum Co Of AmericaVacuum sampler with porous mold insert
US3635791 *Aug 4, 1969Jan 18, 1972Gen Motors CorpPressure pouring in a vacuum environment
US3774668 *Mar 19, 1971Nov 27, 1973Sulzer AgVacuum casting apparatus
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4340108 *May 29, 1980Jul 20, 1982Hitchiner Manufacturing Co., Inc.Method of casting metal in sand mold using reduced pressure
US4355680 *Nov 3, 1980Oct 26, 1982Caterpillar Tractor Co.Method and apparatus for continuous casting of hollow articles
US4374799 *Jun 17, 1980Feb 22, 1983Clerc De Bussy LeMethod for casting parts made of fused ceramic material
US4589466 *May 28, 1985May 20, 1986Hitchiner Manufacturing Co., Inc.Metal casting
US4606396 *Jan 27, 1984Aug 19, 1986Hitchiner Manufacturing Co., Inc.Sand mold and apparatus for reduced pressure casting
US4651799 *Jan 30, 1986Mar 24, 1987Hitchiner Manufacturing Co., Inc.Vented casting molds and process of making the same
US4658881 *Feb 28, 1986Apr 21, 1987M. C. L. Co., Ltd.Casting apparatus for providing controlled ambient during production casting
US4673025 *Apr 4, 1986Jun 16, 1987Inductotherm CorporationApparatus and method for maintaining constant molten metal level in metal casting
US4721149 *Feb 17, 1987Jan 26, 1988Brunswick CorporationLost foam casting system with high yield sprue
US4745620 *Nov 18, 1986May 17, 1988Inductotherm CorporationApparatus and method for maintaining constant molten metal level in metal casting
US4763717 *Apr 18, 1983Aug 16, 1988Pierre LajoyeCentrifugal method and apparatus for melting and casting of metal alloys
US4787434 *Dec 29, 1986Nov 29, 1988Brunswick CorporationVacuum lift foam filled casting system
US4830085 *Feb 26, 1988May 16, 1989Brunswick CorporationVacuum lift foam filled casting system
US4901781 *Aug 30, 1988Feb 20, 1990General Motors CorporationMethod of casting a metal matrix composite
US4966220 *Apr 14, 1989Oct 30, 1990Brunswick CorporationPrecipitation silicon upon cooling
US4982777 *Jan 27, 1989Jan 8, 1991Metal Casting Technology Inc.Countergravity casting method and apparatus
US5042561 *Oct 27, 1989Aug 27, 1991Hitchiner Manufacturing Co., Inc.Apparatus and process for countergravity casting of metal with air exclusion
US5044420 *Aug 13, 1990Sep 3, 1991General Motors CorporationVacuum-assisted, countergravity casting apparatus and method
US5113924 *Aug 17, 1990May 19, 1992Hitchiner Manufacturing Co., Inc.Graphite-free
US5346218 *Sep 28, 1993Sep 13, 1994Wilson Sporting Goods Co.Metal wood golf club with permanently attached internal gates
US5358027 *Mar 5, 1993Oct 25, 1994Cmi InternationalVacuum-assisted gravity pour casting apparatus
US5509458 *Mar 11, 1994Apr 23, 1996Hitachi Metals, Ltd.Vacuum casting apparatus and method using the same
US5735334 *Dec 7, 1992Apr 7, 1998Alloy Technologies LimitedCasting of light metal alloys
US5865054 *Jun 5, 1995Feb 2, 1999Aquaform Inc.Apparatus and method for forming a tubular frame member
US6070643 *Sep 12, 1997Jun 6, 2000Howmet Research CorporationHigh vacuum die casting
US6209616Jun 19, 1998Apr 3, 2001Richard F. PolichVacuum-assisted, gravity-fed casting apparatus and method
US6360810Feb 23, 1999Mar 26, 2002Ati Properties, Inc.Vacuum induction melting system
US6499529Aug 17, 2001Dec 31, 2002Hitchiner Manufacturing Co., Inc.Centrifugal countergravity casting
US6523598Jan 9, 2002Feb 25, 2003Ati Properties, Inc.Vacuum induction melting system
US6684934May 24, 2000Feb 3, 2004Hitchiner Manufacturing Co., Inc.Countergravity casting method and apparatus
US8312913Feb 22, 2006Nov 20, 2012Milwaukee School Of EngineeringCasting process
DE2939974A1 *Oct 2, 1979Apr 10, 1980Hitchiner Manufacturing CoVerfahren zum giessen von metall in eine selbsttragende, gasdurchlaessige sandorm und sandform sowie giessvorrichtung zur durchfuehrung des verfahrens
DE3815828A1 *May 9, 1988Nov 17, 1988Metal Casting TechVerfahren und vorrichtung zum steigenden giessen von metall unter luftausschluss
EP0071449A1 *Jul 26, 1982Feb 9, 1983E.I. Du Pont De Nemours And CompanyCeramic shell mold for casting metal matrix composites
EP0240128A2 *Mar 5, 1987Oct 7, 1987Inductotherm Corp.Apparatus and method for providing constant molten metal level in gaspermeable shell mold metal casting
Classifications
U.S. Classification164/255, 164/66.1, 164/62, 249/120, 164/63, 164/363, 164/306, 164/256
International ClassificationB22D18/06
Cooperative ClassificationB22D18/06
European ClassificationB22D18/06