Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/10—Cores; Manufacture or installation of cores
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C25/00—Foundry moulding plants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C5/00—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
  • B22C5/06—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by sieving or magnetic separating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/10—Cores; Manufacture or installation of cores
  • B22C9/103—Multipart cores
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D15/00—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor
  • B22D15/02—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor of cylinders, pistons, bearing shells or like thin-walled objects
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D47/00—Casting plants
  • B22D47/02—Casting plants for both moulding and casting

Definitions

• This invention relates to methods and apparatus for use in casting, particularly for use in casting large, iron alloy articles such as cylinder heads and cylinder blocks for internal combustion engines.
• Green sand mold is a mixture of sand, clay and water that has been pressure formed into the mold element. Green sand molds have sufficient thickness so that they provide sufficient structural integrity to contain the molten metal during casting and thereby form the exterior walls of the casting. The structural integrity of the green sand molds, however, is not completely satisfactory and the green sand can easily yield to the pressure that may be exerted by the hands of a workman.
• a green sand mold is provided with a cavity and preformed cavity portions to position and hold core elements that form the exhaust gas, air intake, and coolant passageways and other internal passageways in the cast cylinder head.
• the coolant passages are frequently formed with two core elements to permit the interlacing of a one-piece core element forming the plurality of air intake passageways to the cylinders and a one-piece core forming the plurality of exhaust gas passageways from the plurality of cylinders.
• a first element of the coolant core is placed in the green sand mold and core elements forming the passageways for the air intakes, and for the cylinder exhausts are then placed in the green sand mold and the second element of the coolant core is joined with the first element of the coolant core, frequently with the use of adhesive.
• This method entails substantial labor costs and opportunities for unreliable castings.
• a core assembly includes for example a one-piece coolant jacket core, a one-piece exhaust core and a one-piece air intake core, all reliably positioned and held together in an integral core assembly that eliminates the more unreliable core element assembly by manufacturing personnel in the green sand mold.
• the integral core assembly was placed in the green sand mold as a whole prior to pouring the molten iron alloy into the green sand mold.
• the core elements that form the internal passageways of the cylinder head are formed with a high-grade "core sand" mixed with a curing resin so that core elements may be formed by compressing the core sand-curing agent mixture, and curing the resin while compressed to form core elements that have sufficient structural integrity to withstand handling and the forces imposed against their outer surfaces by the molten metal that is poured into the mold cavity.
• the core sand resin is selected to degrade at temperatures on the order of 300 to 400 degrees Fahrenheit so that the core sand may be removed from the interior of the cylinder head after the molten iron alloy has solidified.
• the sand be recovered for further use after it has been removed from the casting Recovery of the green sand used in the mold is also desirable, however, the large quantities of the green sand-clay mixture can be degraded sufficiently during the casting process that they cannot be economically recycled and must be hauled away from the foundry and dumped Since the production of such castings is frequently hundreds of thousands of cylinder heads per year, the cost of handling and disposing of the green sand residue of the casting process imposes a significant unproductive cost in the operation of the foundry In addition, the core sand frequently becomes mixed with the green sand to such an extent that the core sand cannot be reused in the casting process
• the invention eliminates the use of green sand by replacing green sand molds with a "core sand" assembly that can provide, during casting, both the internal and external surfaces of the cylinder head or other casting, such as a cylinder block
• a mold is formed from the same core sand that is used to form the core elements defining the internal passageways of the casting
• the mold and core elements, both of which are formed from core sand are assembled, they are placed in a carrier with sides that hold the assembled mold and core elements together during pouring of the molten iron alloy into the mold-core assembly and the cooling period during which the molten iron alloy solidifies to form the casting
• the carrier for the mold-core assembly may take several forms, including, for example, an insulative shell cast from refractory lining materials used, for example, in lining a smelting furnace
• the refractory shell may have sufficient thickness to support the core sand mold-core assembly during pouring operations, or may comprise a thinner walled refractory shell carried
• a plurality of mold carriers are provided and a plurality of core sand mold-core assemblies are provided
• the mold-core assemblies comprise core sand mold-forming elements and core sand core-forming elements.
• the mold-core assemblies are loaded, one after another, into the mold carriers and are transported to a pouring station where the core sand mold-core assemblies are filled with molten metal.
• the poured mold-core assemblies and carriers are then allowed to cool until the castings are formed and are transferred after the cooling period to an unloading station where the carriers are inverted, the castings are retrieved and the core sand is removed from the interior cavities of the castings.
• the castings are then ready for inspection and further machining operations, and the core sand is recovered and returned to provide a further plurality of core sand elements, either mold elements or core elements or both.
• the use of green sand is eliminated by replacing the green sand molds with a combination of reusable, mold-core assembly carriers and mold elements and core elements that are formed by core sand.
• Fig. 1 is a perspective view, partially broken away, of one embodiment of a mold- core assembly carrier used in the invention
• Fig. 2 is a perspective view of a mold-core assembly of the invention, with the mold elements separated to illustrate the internal core assembly;
• Fig. 3 illustrates the placement of the mold-core assembly of Fig. 2 in the mold- core carrier of Fig. 1 ;
• Fig. 4 is a block diagram of the process of the invention.
• Fig. 5 is a perspective view of another embodiment of a mold-core assembly carrier used in the invention.
• Fig. 6 is a perspective view of a presently preferred embodiment of a mold-core assembly carrier used in the invention. DETAILED DESCRIPTION OF THE BEST MODE OF THE INVENTION
• Fig 1 is a perspective view of one embodiment of a mold-core assembly carrier 10 used in the process illustrated in the block diagram of Fig 4
• the carrier 10 for the mold-core assembly may include a liner 11 , formed from a castable refractory material such as the refractory materials used to line the furnaces of iron smelting ovens
• a refractory liner 11 can be carried in a steel jacket 12
• Fig 1 illustrates steel jacket 12 as encompassing the liner 11 , except at its open top, with sufficient structural strength in the refractory liner, the steel jacket may be reduced to a supporting steel frame made, for example, from angle and strap iron as shown in Fig 5
• Fig 1 is partially broken away at one end to illustrate the refractory liner 11
• steel jacket 12 may be provided with pivot pins 13 located on an axis of rotation 14 below the center of gravity of the carrier 10 so that the carrier 10 will invert unless supported in an upright position
• steel jacket 12 may be optionally provided with one or more openings 15 to permit the refractory liner 11 to be more easily broken out of the steel sleeve 12 if it needs to be replaced
• Fig 2 illustrates a mold-core assembly 20 including mold elements 21 and 22 that are formed with core sand and resin
• the lower mold element 22 is provided with surfaces 22a to position a core assembly 23 which will generally comprise a plurality of assembled core elements, each of which is formed from the core sand used in the mold elements 21 and 22
• the mold elements 21 and 22 are provided with a passageway 24 into which the molten iron alloy may be poured and carried to fill the mold cavity 25 in this invention
• the core assembly 23 may include interior surfaces that cooperate with the mold halves 21 , 22 to form outer surfaces of the casting as well as its interior passageways
• the underside of the core assembly 23 may be provided with a cavity portion adjacent a portion of its exterior (on the underside of core assembly 23 and not shown in Fig 2)
• Fig 2 illustrates the passageway 24 for the molten iron alloy as being formed in both mold elements 21 and 22 the passageway may be formed predominantly in one mold element In the mold-core assembly 20, the upper mold element 21 is
• the mold-core assembly 20 is then lowered into the central cavity 11a of the carrier 10 with the opening 24 for receipt of the molten iron alloy facing upwardly, as shown in Fig. 3.
• the interior sides of cavity 11 a may be tapered to allow the weight of the mold-core assembly 20 to retain core elements 21 and 22 in a closed relationship. It will be noted that the taper of the sides of the cavity 11a and cavity 40a (Fig. 6) is greatly exaggerated for illustrative purposes.
• a plurality of carriers 10 are provided in first step 100 of the process and a plurality of mold-core assemblies 20, illustrated in Fig. 2, are provided in another first step 101 of the process.
• the mold-core assemblies 20 are placed in the carriers 10, shown in Fig. 3, at step 102 and are transported to a pouring station 103 where molten iron alloy is poured into the mold- core assemblies 20 through their pour openings 24.
• the carriers 10 and poured mold- core assemblies 20 are then placed in a holding area for a period, for example, about 45 minutes, to permit the molten iron alloy to solidify and form the casting, the holding period being illustrated in Fig. 4 by the broken line between steps 103 and 104.
• the carriers 10 are moved to an unloading station 104 where the carriers are permitted to invert, dumping the casting and the remnants of the mold-core assembly for further processing.
• the core sand from both the mold elements 21 22 and core elements 23 of the mold-core assemblies 20 is recovered at step 105 for return and reuse to provide further mold elements or core elements or both, as shown by line 106.
• the recovered core sand may be rehabilitated, for example, by supplying it with further resin before using the recovered core sand to provide the mold-core assemblies at step 101.
• Fig. 5 illustrates an alternative embodiment of carrier 30 that may be used in the invention, in which the mold-core assembly 20 is to be carried by a relatively thin refractory liner 31.
• the refractory liner 31 is supported by a structural framework 32, for example, a weldment of angle iron 33 and strap iron 34 spaced so that the combination of structural support 32 and liner 31 support the mold-core assembly 20 during pouring.
• the liner 31 may be formed by thin metal sheets supported by a structural framework 32.
• Fig. 6 illustrates, in a perspective view, a presently preferred embodiment of a mold-core assembly carrier 40 for provision at step 100 of Fig. 4.
• the preferred mold- core carrier 40 of Fig. 6 does not employ a refractory material liner. Rather, in the carrier 40, two thin replaceable metal sheets 41 are used to engage the sides of the mold-core assembly 20 and, as a result of their positioning, to hold the mold-core assembly together during pouring and cooling of the casting metal (steps 103 and 104 of Fig. 4).
• the two thin, replaceable metal sheets 41 which can be, for example, steel sheets % inch thick, are inserted into a structural framework 42 and may be held in place by tack welding.
• the structural framework 42 can comprise a pair of tapered framework ends 43 held in position by a plurality of side slats 44 which are welded at their ends to the framework ends 43. As indicated by Fig. 6, the slats 44 are widely separated to expose the outside surfaces of the thin metal sheets 41 to ambient atmosphere for cooling the casting.
• At least one of the metal sheets 41 may be floatably received in the framework, as by a plurality of studs 48 attached to the sheet 41 and extending through the slats 44 wherein lock nuts 49 are spaced on the studs 48 away from the sheet so that the sheet may slide on the studs 48 to seek its own angle as the mold core assembly is inserted in the carrier 40 so that the surface of sheet 41 may conform to the adjacent surface of the mold-core assembly 20 to provide a snug fit therewith during pouring.
• the framework ends 43 may be provided with pivot pins 45 to permit inversion of the carrier 40 at the unloading station, step 104.
• the carrier may be provided with a knock-out mechanism, which can include, for example, a cam 46 operated by a cam- operating surface adjacent to a conveyor on which the inverted carrier 40 is being moved at station 104.
• Fig. 6 further illustrates a frame 47 for carrying and storing the carrier 40.
• the mold-core assemblies 20 are placed into the central cavities 40a of the carriers 40 between the thin replaceable metal sheets 41 through their top openings at step 102 and are transported to a pouring station 103 where molten iron alloy is poured into the mold-core assemblies 20 through their pour openings 24
• the carriers 40 and poured mold-core assemblies 20 are then placed in a holding area for a period, for example, about 45 minutes, the holding period being illustrated in Fig 4 by the broken line between steps 103 and 104, to permit the molten iron alloy to solidify and form the castings
• the carriers 40 are moved to an unloading station 104 where the carriers are inverted and their knock-out mechanisms are operated, for example, by the engagement of cam 46 with a cam- operating surface at unloading station 104, dumping the casting and the remnants of the mold-core assembly for further processing
• the core sand from both the mold elements 21 , 22 and core elements 23 of the mold-core assemblies 20 is recovered at step

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)
• Casting Devices For Molds (AREA)
• Cylinder Crankcases Of Internal Combustion Engines (AREA)
• Processing Of Solid Wastes (AREA)
• Treatment Of Steel In Its Molten State (AREA)

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• 2000
  • 2000-06-30 DE DE60020858T patent/DE60020858T2/de not_active Expired - Lifetime
  • 2000-06-30 WO PCT/US2000/018379 patent/WO2001002113A1/en not_active Ceased
  • 2000-06-30 AT AT00945150T patent/ATE297823T1/de active
  • 2000-06-30 BR BRPI0012465-6A patent/BR0012465B1/pt not_active IP Right Cessation
  • 2000-06-30 JP JP2001507593A patent/JP2003503211A/ja active Pending
  • 2000-06-30 EP EP00945150A patent/EP1218126B1/en not_active Expired - Lifetime
  • 2000-06-30 KR KR1020017016959A patent/KR100676569B1/ko not_active Expired - Fee Related
  • 2000-06-30 US US09/608,176 patent/US6644381B1/en not_active Expired - Lifetime
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  • 2000-06-30 AU AU59134/00A patent/AU5913400A/en not_active Abandoned
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• 2012
  • 2012-03-26 JP JP2012070163A patent/JP5356564B2/ja not_active Expired - Fee Related

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