CA2103136C

CA2103136C - Method and apparatus for heat treating metal castings

Info

Publication number: CA2103136C
Application number: CA 2103136
Authority: CA
Inventors: Paul M. Crafton; Scott P. Crafton
Original assignee: Consolidated Engineering Co Inc
Current assignee: Consolidated Engineering Co Inc
Priority date: 1991-05-24
Filing date: 1992-04-15
Publication date: 1997-12-23
Anticipated expiration: 2012-04-15
Also published as: AU663088B2; KR970005373B1; JPH08224656A; ES2107438T5; AU1906292A; ES2107438T3; JP2851574B2; JP2620027B2; JPH06507839A; CA2103136A1; MX9202441A; EP0546210B2; AU690776B2; AU4076395A; EP0546210B1; WO1992020478A1; BR9206048A; EP0546210A1

Abstract

An improved method and apparatus for heat treating a metal casting having a sand core comprising a heat treating furnace (11), with fans (44) for directing a flow of air over the casting to dislodge the sand core. The dislodged sand falls into a trough (50) where it is collected and conveyed to a central collection bin (60) for reuse.

Description

lo METEIOD AND APPARATUS FOR H~AT
TREATING METAL CASTINGS

Technical Field The present invention relates generally to methods and apparatus for heat treating hollow metal c~ting~, and relates more specifically to an improved method and apparatus for heat treating metal castings with sand cores which provides for removal of the sand core and for recovery of the sand core material for reuse.

B~ckground of the Invention Methods and apparatus for manufacturing hollow metal castings such as cylinder heads, engine blocks, and the like are well known. Conventional prior art processes ~or manufacturing aluminum castings ~ypically employ a cast iron "flask-typel' mold having the exterior features ofthe block forrned on the interior walls ofthe mold A sand core, pre-molded from a mixture of sand and an organic binder and . s, ,, i WO 92J2047~ PC'r/US92/03079 ~
~l 03136 having interior features of the casting formed on by it~
exterior surface, is placed within the mold. The mold is ~hen filled with molten aluminum alloy.
After the aluminum alloy has solidified, the casting is removed from the mold. Because untreated aluminum alloys may be softer or less strong than desired, it is often necessary to heat treat the casting to strengthen or harden the metal. According to conventional manufacturing processes, before the casting is heat treated, the sand is o removed from the interior of the casting. An operator chisels the sand out of the interior of the wor}~piece wi~h a pneumatic chisel. The casting may then be fed into a "sh~keout" system, a vibrating table which agitates the casting to further brea~; up dle sand and dislodge it from the interior of the casting. When the sand has been removed, the casting is heat-treated in a conventional m~nner by heating the casting to a high temperature and then quenching the casting. Optionally, the casting may further be heated at a lower temperature to "age"
the al~lmimlm alloy.
If it is then desired to recover the sand removed from the interior of the casting for subsequent reuse, additional steps must be taken to process the sand. l'he sand removed by chiseling and shaking the casting is fed into a sand burnout unit to bum off the binders.
Prior art processes for manufacturing aluminum alloy castings suffer a number of disadvantages. The steps of removing the sand from the interior of the casting by chiseling and sh~ing not infrequently result in damage or scarring to the as-then unhardened alunlinum alloy. Further, the shakeoul process must be carried out manually and is thus labor-intensive, thereby increasing the expense of the manufacturing process. Also, the additional steps required to salvage the sand for reuse are time-consuming and require additional labor and equipment expense. The sand recovery process is costly and WO 92/2047X 2 1 0 3 1 3 S PCr/~lS92/03079 presents certain environmental problems concerning the handling of the binder was~e products.
Efforts have been made to overcome some of the disadvantages associated with prior art methods and apparatus for sand-casting metal objects. One exarnple is disclosed in U.S. Patent No. 4,41 1,709, wherein a method for the manufaclure of aluminum alloy castings comprises pouring a molten ~ nninllm alloy into a mold having therein a sand core forrned from sand and an organic resin binder. After the o alloy solidifies, the casting is shaken or vibrated to destroy the core, and appro~ tely half of the sand used to form the core can readily be removed from the casting. Subsequently, the casting is he~te~, and Ihe organic resin binder in the remaining portion of the sand core is burned off. The sand is thus unbonded such that about 80% of the remaining sand (approxirn~tely io% of the total core sand) falls from the casting by force of gravity. Thereafter, the casting is quenched in a water bath, and the rem~ining sand in the c~stin~ is removed by flowing water ~rough the casting.
While ~e method disclosed in the aforementioned U.S. Patent No. 4,411,709 af~ords certain benefits over the prior art by eli~in~ting the process of vibrating the sand core from the casting, it still suffers certain disadvantages in that i does not climin~te the requirement for s~ ing or agitating the 2s casting prior to heat treating, nor does it eliminate the additional processing steps needed to recover the sand for subsequent reuse. The aforementioned patent also does not include an age hardening process for increasing the hardness of the metal. Further, since the method disclosed in the aforementioned U.S. Palent No. 4,411,709 relies upon force of gravity to remove the sand from the casting, sand will remain on flat and upwardly concave surfaces after the binder has bumed off.

~0 92/20478 PCr/US92/03079 .~ ' ~
21i)313~ 4 Summary of the Invention As will be seen, the present invention overcomes ~hese and other disadvantages associated with prior art casting processes. Stated generally, the present invention provides an improved method and apparatus for heat treating metal castings with sand cores which provides for removal of the sand core and recovery of the sand core material for reuse.
The method and apparatus of the present invention elin~linates the need for chiseling or sh~king the casting prior to hea~
o treating, thereby eliminating the possibility of damage associated with those steps. In addition, the present invention recovers the sand in a clean state.
Stated more specifically, the present invention comprises an apparatus for heat treating a metal casting having a sand core comprising sand bound by a binder. A furnace includes a work ~n~ber for ~eceiving the casting ~erewithin.
A ~ti~lg me~ns heats the work cl arrlber such that the casting and its sand core are heated to a temperature sufficient to combust the binder of the sand core. Thus, the binder is burned off, leaving only the sand of the sand core. The apparatus further includes an air~ow means for directing a flow of air over the casting so-as to dislodge a portion of the sand from the casting. A me~ns, for example a screen, disposed within the work ch~r~ber retains portions of the sand core which may become dislodged from said casting prior to the binder being combusted therefrom. A means operativel~
associated with the furnace collects the sand which is dislodged from the casting. lhe sand thus collec~ed is free of binder material and is suitable for reuse.
3() In another aspect, the apparatus of the present invention comprises a quench tank for containing water into which the lle~teA c~stin& is submerged. The tank includes an agitation me~ns for agitating the water so as to dislodge sand remaining in the càsting. A collection means operatively 3s associated with the tank removes the dislodged sand and a wo 92/20478 2 i 3 3 1 3 ~ Pcr/~lsg2/03079 portion of the water from the tan~ and separates a major portion of the water from the sand.
Another aspect of the invention comprises a method for heat treating a metal casting having a sand core s comprising sand bound by a binder. The casling with sand core therewithin is heated to a temperature sufficient to combust the binder of the sand core. Thus, the binder is burned off, leaving only the sand of the sand core. Next, a flow of air is directed over the casting so as to dislodge a o portion of the sand from the casting. Clumps of sanld core material which become dislodged from said casting prior to the binder material being combusted therefrom are captured and retained within the fumace to permit the binder material to be combusted therefrom. The sand dislodged from the casting is dlen collçc~e~ e sand thus ~ollected being free of binder material arid suitable for reuse.
Thus, it is an objec~ of the present invention to provide an improved method and apparatus for heat trealing metal castings.
It is another object of the present invention to provide an improved method and apparatus for removing the sand cores from metal castings.
Another object of the present invention is to provide a method and apparatus which removes the sand core from a metal ~asting which rrinimizes the risl~ of damage resl-ltirl& to the casting.
It is a further obiect of the present invention to provide a method and apparatus for removing the sand core from a metal casting which requires less labor and expense than conve-~tiorl~l methods and apparatus.
Yet another object of the present invention is to provide a method and apparatus for removing a sand core from a casting which recovers the core material in a state suitable for reuse, thereby elilnin~ting the need for additional 3s ~rocessing of the recovered sand.

~ ) t, 13 G 6 Other objects, features, and advantages of the present invention will become apparenl upon reading the following specification, when taken in conjunction with the drawings and the appended claims.

Brief Description of lhe Drawings Fig. 1 is a top plan view of a first embodiment of an apparatus for heat treating, quenching, and aging metal castings according to the present invention.
o Fig. 2 is a side cut-away view of the heat treating furnace of the apparatus of Fig. 1.
Fig. 3 is an end cut-away view of the heat treating fumace of Fig. 2.
Fig. 4 is a side cut-away view of the quench tank of the apparatus of Fig. 1.
Fig. 5 is an end cut-away view of the aging oven of the apparatus of Fig. 1.
Fig. 6 is a side cut-away view of an alternate embodirnent of an apparatus for heat treating, quenching, and aging metal castings according to the present invention.

Detailed Description~ of the Disclosed Embodiment Referring now to the drawings, in which like nllmerals indicate like ele~ne~ts throughout the several views, Fig. 1 shows an apparatus 10 for heat-treating and aging metal castings according to the present invention. In the disclosed embodiment, the metal castings are cylinder heads which are cast from an aluminum alloy in a conventional manner. The casting process is well known to those skilled in ~he art and comprises no part of the present invention.
Accordingly, the casting process will be described only briefly.
The casting process employs a cast iron flask-type mold having the exterior features of the cylinder head fo~ned on its interior surfaces. A sand core comprised of sand and a WO 9~/20478 PCI /US92/03079 ~iO31~

suitable binder material and defining the interior features of the casting is placed within the mold. Depending upon the applica~ion, the binder may comprise a phenolic resin binder, a phenolic urethane "cold box" binder, or other suitable s organic binder material. The mold is then filled with a molten al.~ ..., alloy. When the alloy has solidified, the c~s~ing is removed from the mold and is now ready for heat tre, ~g and aging.
The heat treating and aging apparatus comprises a o heat treating furnace 11, a quench tanlc 12, and an aging oven 13. ln the disclosed embo~ nent, these three components are laid out in a "U" s~ ell configuration, with the heat treating fumace 11 comprising one leg of the "U", the quench tank 12 comprising the base of the "U", and the aging oven 13 s comprising the other leg of the "U". However, other con~lgurations, such as an in-line configuration or an L-shaped aligtl~Gn~, may be employed as spase constraults may dictate.
Referring now to Figs. 2 and 3, the heat treating furnace 11 defines a work chamber lS therewilhin. The furnace 11 comprises a number of different zones 16, the nature and purpose of which will become apparent. In the disclosed embodiment, the furnace comprises eight ~ones, designated by the re~erence numerals 16AoH. However, the number of zones 16 is not crucial, and the furnace may be zs divided into a greater or lesser number of zones as the individual application may require.
Wi~hin each zone of the fumace 11, a pair of burners 18 are mounted in the vertical side walls 19 and are diagonally disposed to fire in opposi~e directions to heat the work chamber 15 of the furnace. The burners l8 are conventional me(liuln velocity, tempered air burners which are commercially available from a number of different manufactu~ers. As can be seen in ~ig. 3, each bumer 18 includes a fuel line 20 for supplying natural gas to the bumer.
3s A combustion air blower 21 in communication with the burner by means of an air line 22 supplies combustion air to the bumer. A butterfly valve 23 located within the air line 22 is adjustable to control the volume of air delivered to the bu~ner 18.
s The burners 18 are designed to heat the wor};
chamber I S of the furnace 11 to a temperature of approximately 850~-1000~F. In the disclosed embodiment, the work chamber lS is heated to a temperature of approxinnately . .
980~P. The butterfly valves 23 for the first zone 16A and the o fourth through eighth zones 16D-H are adjusted to introduce 1~13% oxygen to their respective burners 18. The butterfly valves 23 for the second and third zones 16B, 16C are adjusted to introduce 13-17% oxygen to their respective burners 18. The function and purpose of controlling the ~s amount of oxygen delivered to the various zones 16 will be explained below.
The fumace 11 further includes a prehea~
ch~rnber 24 disposed upline of the heating zones 16. Exhaus~
gases from the heating ~ones 16 are directed through the preheat chamber 24 and heat the chamber to a temperature of approximately ~00~-700~F. By utilizing waste gases rather than burners to heat the preheat chamber 24, considerable energy saYings are rea!ized. The fun~ace 11 has an input door 25 at i~s upper end 26 and a discharge door 27 at its lower end 28. Another door 29 separates the preheat chamber 24 from the heating zones 16. To inhibit the loss of heat through the furnace walls, a layer of ceramic fiber insulation 30 is disposed just inside the outer fumace walls 31. A me~al liner 32 is disposed on the inner side of the ceramic fiber insulation. The pwpose of the metal liner 32 is to protect the jns~ tjon 31 from the abrasive effects of flying sand, as will be more fully explained below.
Within the work chamber lS of the fumace 11 is a roller hearth 34 comprising a plurality of driven roller~ 36 3s for supporting and conveying workpieces through the f~mace WO 92/20478 PC'r/US92/03079 ~ ~ ~' 3 1 :,~

in a direction of travel indicated by the arrow 38. The roller hearth 34 and drive mech~nism for driving the rollers 36 are of conventional design well known to those skilled in the art.
At the entry and exit locations of the furnace 11, the roller s hearth 34 comprises high speed clutch actuated rollers for transporting the workpieces rapidly into and out of the furnace. In addition, the portion of the roller hearth 34 which transports the workpieces from the preheat chamber 24 into the heating zones 16 of the fumace also comprises high speed, o clutch actuated rollers. The major portion of the roller hearth 34 disposed within the furnace 11 is driven at a constant speed.
To facilitate 1Q~ of castings into the furnace 11 and transport of the c~ctin~s through the furnace, the castings are lo~de~ into b~c~pts 40 which, in tum, are loaded onto the roller hearth 34 to be conveyed through the furnace.
In the disclosed embodiment, each basket 40 holds forty to fifty workpieces. The ~sl~ets 40 are of open construction to perrnit sand dislodged from the workpieces to fall freely out of tbe basket. To facilitate removal of the sand from the workpieces, the workpieces may advantageously be angled within the bPc~ets 40 so that the sand ~,vill more easily fall out.
With further reference ~o the roller hearth 34, the speed with which the roller hearth conveys ~e wor}~pieces through the furnace 11 is a f!~nction of ~he production capacity of the apparatus 10. Thus, in the disclosed embodiment where the furnace 11 must accommodate a new basket of workpieces every thirty-five minutes, ~he roller hear~h 34 must have conveyed the previous basket of workpieces within thirty-five 3~ minutes by a dist~nce at least suf~lcient to permit the next basket of workpieces to be introduced into the fumace. In the disclosed embor1irne~ based upon the size of the baske~s and the production requirerne-~ts of the apparatus, the roller hear~h 34 conveys the workpieces through the fumace 11 a~ a speed 3s of approxiln~tely six feet per hour.

WO 92/2W78 PCI'/US92/03079 ,~

210313G lO

It will be appreciated by those skilled in the art that given the speed of ~he roller hearth 34, the dwell time, that is, the time for which the workpieces are exposed within the work chamber lS of the fwnace ll, is a function of the s length of the furnace. For a roller hearth 34 which moves at six feet per hour, where it is desired to heat lreat the workpieces for six hours, the furnace ll must be at least thirty-six feet in length plus the length of one baslcet 40 and door end clearance space.
o At the vertical center line of each zone, an axial fan 44 is mo1~n~ed in the top 45 of the fumace ll. The fan 44 circ~ tes the air within the c~--csl,onding zone to provide an airflow of 3000-5000 feet per mirllltc~ In the first five zones 16A-E of the fumace ll, the fan 44 directs its airflow lS downward into the work ch~rnber 15 by meanc of ductwork 46. In the sixth zone lCF, the airflow is directed hori70nt~11y over the workpieces by side-flow ductwork (not shown). In - the ~eventh zone 16G, the fan 44 draws air upwardly through the work çh~nber lS. In the eighth zone 16H, the fan 44 once again directs its airflow downward into the work ch~mber lS by me~n~ of ductwork 46 in a manner similar to the first ~lve zones 16A-E. The reason for the varying airflow patterns within.the various zones 16 will be more fully explained below.
2s Disposed within the furnace ll beneath the roller hearth 34 are a plurality of st~in1ess steel troughs 50 whose pu~pose is to collect sand which falls from the castings within - the work chamber 15. The interior walls of the troughs 50 are smooth and are disposed at a 45~ angle with respect to horizontal. The walls are sufficiently angled that sand will scttle into the bottom of the trough 50 without "bridging."
While conventional troughs for h~ndling wet sand typically havc walls angled as much as 60~, it will be appreciated that lhc troughs 50 within the furnace 11 will be handling only 3S CA~ICUIC1Y dry sand, and walls angled at even less than 45~ will WO !~/20478 2 1 ~ 3 1 3 1'~ PCr/US92/03079 collect the sand without permitting the sand to bridge the trough.
A one-quarter inch screen 52 is positioned beneath the roller hearth 34 and over the troughs 50 in each of the first three zones 16A-C. The screens 52 capture particles larger than one-quarter inch which are dislodged from the castings and prevent these larger particles from passing into the trough 50. Any clumps of core material which may becorl~e dislodged from the workpieces before the o phenolic resin binder fusing the core together has been complelely bumed off will be ret~ined on the screens 52. The clumps of core material collected on the screens 52 will contin-le to be exposed to the heat and oxygen-rich airflow within the fumace 11 until the binders have burned off, at which time the clumps will ~isintegrate. When the clumps have ~ ntegrated to a size m ~11er than one-quarter inch, the sand will fall through thc screcns 52.
It has been found that a screen size of sm~ller than one-quarter inch is not practical, since flashings.which are dislodged from the castings will tend to clog a finer screen.
Also, while screens 52 may be pssitioned across the troughs 50 in all of the zones 16A-H if desired, it has been found that by far the greatest risk of clumps of core material becoming dislodged from d~e castings occurs within the first three zones 16A-C. Thus, in the disclosed embodiment, screens are provided only over the troughs in zones 16A-C, and screens o~.rer the ~roughs in the remaining zones 16D-H are not necess~ry.
The disclosed embodiment further comprises a plurality of inverted V-shaped baffles 53 disposed over the troughs 50 and belle~t1l the screens 52. Sand passing through the screens 52 will strike the baMes 53 and tumble down the sloped sides of the baffles. Tbus, any remaining small clumps of sand will be broken up further before falling into the 3s troughs 50. ln the disclosed embodiment, the baffles 53 have WO 92/20478 PCT/I_'S92/03079 ,<. .

2io3136 12 upturned flanges at their lower ends which provide structural rigidity to the bafnes and also comprise another surface for sand particles to impact before falling into the trou~hs ~0.
Referring in more detail to the ductwork 46 illustrated in FIG. 3, the ductwork includes vertical walls 5~
which tenninate at a lower end 55. A narrow gap ~6 is fo~ned between the lower end SS of the ductwork 46 and the roller hearth 34. The dimensions of the gap 56 are closely controlled so as not to provide a retum airflow path above the roller hearth 34. Instead~ the airflow is forced between the rollers 36 and sweeps over the screen52 and the baffles 53 before returning upwardly outside the vertical walls 54 of the ductwork 46. The importance of this airflow pattern will be explained below.
s One end of a screw conveyer or auger 58 is in communication with the bottom of each trough j0 and is ad~pted to remove the sand which collects in the respective trough. ln the ~isclosed embo~i~ent, it has been determined that the screw conveyers ~8 need run only periodically in order to keep the troughs 50 emptied. Because the major portion of the sand will be collected within the troughs in the first three heating zones 16A-C, the augers 58 associated with those troughs run for two minutes out of every fifteen minute period. The remaining screw conveyers 58 run for two 2s minutes out of every twenty-~lve minute period. All of the screw conveycrs 58 empty onto a steel vibratory sand conveyer 59 which comprises a reciprocating steel bed capable of accommodating material as hot as 900~F. without being damaged. The conveyer 59 transports the reclaimed sand to a central collection bin 60 to await reuse.
Referring now to Fig. 4, at the downline end of the heat treating fumace is the quench tank 12. The capacity of the quench tank 12 is a function of the size and number of workpieces being immersed at a single time, the specific heat 3s of the alloy comprising the workpieces, and the temperature to W092/204~X f~ 1 ~ 3 1 3 S PCI/US92/03079 which the workpieces have been heated. Preferably, the quench tank 12 should hold sufficient water that the immersion of a load of workpieces into the tank will raise the temperature of the water by no more than 10~F. In the s ~lisclo~ed embodiment, this requirement is met by a quench tank 12 having a capacity of 4,000 gallons of water.
The quench tank 12 includes a conven~ional rack arr~-lE~..,c..t 62 for immersing tbe ~cket of workpieces in the tank. The rack 62 has a plurality of driven rollers 64 for drawing the workpieces onto the rack. The basket of workpieces is l~q~e~ onto the rack 62 while the rack is in its niscd position, ir.~ic~d by ~e solid lines in Fig. 4. At that point, thc rollcr drive ~nech~lis~n is disengaged, and the rack 62 with workpieces thereon is lowered into the tank 12 by lS means of a pn~m~iC cylinder (not shown) until the basket of workpieces rescl~es the lowennost position, shown by the dotted lines in Fig. 4. The ~ çnGh tank 12 is fully automatic and is designed to submerge a load fully within ten seconds af~er the furnace discharge door 27 begins to open. The quench tank 12 preheats the water to a suitab~e quench temperature and includes cooling plates 66 to restore the preq-lenching temperature after each cycle. The quench tanlc 12 also is proYided with twin propeller agitators 68 and direction vanes to agitate thé water in the tank. After the 2S workpieces have been submerged for approximately eight minl~tes~ thé pneumatic cylinder is actuated to raise the rack 62 and lift the workpieces out of the tank 12. As will be appreciated by those skilled in the art, all of the aforementioned features of the quench tank 12 are conventi~
In addition to the foregoing conventional characteristics, the guench tank 12 includes certain other fcatures for recovcring sand which may be loosened from the workpieces during the quenchirlg process. The tank 12 includes a trough 72 within its base such that any sand which WO g2/2047X PCl ~US92/03079 ~ iO~13G 14 becomes dislodged from the castings and setlles out of the water will be collected in the bottom of the trough. A
watertight screw auger 74 is disposed within the bottom of the trough 72, and the auger communicates with a holding area s 76. A double-diaphragm slurTy pump 78 is operative to draw material out of the bottom of the holding area 76 and to convey it to a vibratory sand dryer 80. The vibral~ sand dryer 80 is of conventional design and therefore is s ~vn in the drawings only schematically. l'he sand dryer 80 includes o a vibrating, rotating 150 mesh screen which pennits water but not partic~ te matter larger than 150 mesh to pass through the screen. Particulate mar~ter too hrge to pass through the screen openings is vibrated off onto the sand conveyor 59. Water which passes dlrough the screen falls into a collector beneath IS the screen. The collector in tum is in fluid communica~ion with a 30 gallon holding tank, which is periodically emptied into the quench tank 12.
Workpieces removed from the quench tank 12 are introduced into the aging oven 13 for precipitation hardening to increase the hardness of the castings. The aging oven is of conventional design and will therefore be described only brietly. Wi~h reference to Fig. 5, the aging oven 13 of the disclosed embodiment is a four z~ne oven and comprises a work ch~mber 85. The oven 13 includes outer oven walls 86, an insulating blanket of ceramic fiber 88, and a metal liner 90. A fan 92 located along the longitudinal centerline of the oven 13 circulates hea~ed air throughout the work chamber 85 of the oven. To transport workpieces through the work chamber 85, the oven 13 includes a roller hearth 9~ for conveying workpieces through the oven. As is the case with the roller heanh ~4 of the furnace 11, the sections of the roller heanh 94 which transport the wor}~pieces into and oul of the oven 13 comprise high speed, clutch actuated rollers.
The major portion of the roller hearth 94 which is disposed 3s within the oven 13 transports ~he workpieces at a constant wo 92/2047X 2 i ~ 3 1 ~ ~ PCI~/US92/03079 speed. As hereinabove explained with respect to the speed of the roller hearth 34 of the furnace 11, the minimum speed of the roller hearth 94 is determined by the production requirements of ~he apparatus 10. Given the constraints thus s imposed by the minim~ required speed of the roller hear~h 94, the maximum dwell time of the workpieces within the oven 13 is a function of the length of the oven. In the disclosed embodiment, the dwell time is approximately four hours, though longer ovens for aging periods of up to twenly o hours may be desirable, depending upon the alloy used in the ca,stin~ and the characteristics required of the casting.
The oven 13 includes a number of burners 96 for heating the interior of the ovcn. In the disclosed embodimer~t, the burners 96 heat the interior of the oven to a temperature lS of 450~ + 5~F. However, depen~ling upon the alloy being aged and the hardness desired, the temperature in the oven may range from 250~-500~F.
The aging oven 13 includes a series of troughs 98 located in its lower portion. However, since the vast majority of the sand is removed during the heat treating and quenching steps, the amount of sand reln~ining on the wor}ipieces upon their introduction into Ihe aging oven 13 is, at most, minimal.
Since so little sand is dislodged within the oven 13, no provision is made for automatically collecting and conveying

2~ the sand to a central recl~m~tion location. Instead, th~e troughs 98 may be emptied at relatively long intervals during routine rn~intenance of the oven.
The operalion of the appara~us 10 will now be described. When the molten ~ minum alloy of the castings has solidified, the castings are removed from their respective molds and transferred into one of the baskets 40. Each of the ~sl~ets 40 is large enough to hold forty to fifty workpieces and, as previously mentioned, is of open construction to pe~mit sand to pass freely there~hrough. To fur~her facilitate 3s removal of the sand from the cavities of the workpieces, the WO 92~20478 PCI /US92/03079 ~ia313~' 16 wor~;pieces may advantageously be angled within the basliet 40 so that the s~nd will more easily fall out of lhe wor};pieces.
The basket 40 of workpieces is placed on the roller hearth 34 at the upper end 26 of the furnace 11. The input door 25 of the fumace 11 is opened, and the high speed, clutch actuated rollers transport the basket 40 of worl~pieces into the preheat chamber 24. E~haust gases from the fumace 11 are directed through the preheat chamber 24 and bring the workpieces up to a temperature of about 380~F. The o workpieces are exposed wilhin the preheat chamber 48 until the preceding basket has moved far enough through the fumace to perimit introduction of another basket. Thus, in the disclosed embodiment, the workpieces soak in the preheat ch~n~ber for approximately thirty-five minutes. When the 1S preceAing b~c~el has moved far enough into the furnace to pennit another basket to enter, the door 29 between the preheat ct~ ber 24 and~the work ch~mber lS opens, and high speed, clutch ~ct~l~t~(l rollers transport the bas};et 40 into the work eh~mber.
The natural gas fired burners 18 heat the interior of the furnace 11 to a temperature of approximately 980~F.
This temperature is sufficient not only to heat treat the castings but also to burn off the organic binders fusing the core sand together. Thus, as the castings are heated within the wor}~
chamber 15 of the furnace 11, the binders are burned off of the sand core material. As the binder burns off, the sand comprising the core loosens. The sand is dislodged from the castings by force of gravity and by the 3000-5000 feet per minute airflow within the fumace generated by ~e fans 44.
As previously described, the second and third 16B, 16C of the eight zones 16 are provided wilh 13-17%
oxygcn, while the remaining zones 16A and 16D-H are provided wilh only 1(~13% oxygen. It has been found thal the major ponion of such combustion occurs in the second and 3s ~hird zones; in the first zone 16A, the casting and core are wo 92/20478 ;~ 1 0 3 1 ~3 ~ PCI /US92/03079 being brought up to the combustion temperature of 980~~, and in the later zones 16D-H the combustion has been substan~ially completed. Further, it has been found that, in those zones where the major ponion of ~he combustion occurs, combuslion of the organic binder material will consume approximately 4-S% oxygen. Accordingly, the burners 18 in zones 16B and 16C are adjusted to provide approximately 4-5% more oxygen than the other zones to compensate for lhe oxygen consumed by combustion of the binder material and lo o facilitate the combustion process. ln the remaining zones 16A
and 16D-F, however, the burners 18 are not adjusted to provide the excessive amount of air required by zones 16B
and 16C. Since there is not the excessive amount of air which must be healed, the burners in those zones where less combustion occurs can operate more efficiently than if the higher volume of air were provided to all zones of the fumace.
The workpieces and the sand cores within the workpieces are heated to a temperature of 980~F. over the course of approYim~tely one hour. After the workpieces have reached the "soak" temperature of 980~F., ~hey remain in the fumace for an additional five hours, for six total hours of exposure within the fumace. In other applications, depending upon the alloy used and the metalurgical characteristics desired, the soak time may be as long as twelve hours or as short as four hours.
As the workpieces are conveyed through the first five zones 16A-E, they are subjected tO a downward directed flow of turbulent air. As the workpieces pass into the sixth zone 1 6F, the side-flow ductwork redirec~s the airflow horizontally over the workpieces. Then, as the wor~ipieces pass into the seventh zone 16G of the fumace 11, they are subjected to an upwardly directed turbulent airflow, caused by the respective one of the fans 44 drawing air upwardly 3s tbrougb the wor}; ~h~rnber 15. Finally, as the workpieces pass WO 92/2047X PCT/IIS92/03079 .
~10313~ ' through the eighth zone 1 6H, the workpieces are again exposed to a downward directed airflow. This succession of downward, sideways, upward, and downward turbulent airflows is successful in dislodging about ~5% of the sand s from the workpieces.
As will be clear to those skilled in the art, sand panicles being blown about inside the furnace by the 3000-5000 feet per minute airflow have a significant potential for ab~asion to the interior surfaces of the fumace 11. The metal ~oliner 32 can thus be appreciated for the protection it affords against damage to the fumace's ceramic fiber insulation 31.
The sand dislodged from the castings falls through the basket 40, passes through the s~ce~ between the rollers 36 of the roller hearth 34, falls through the screens 52, strikes ISthe baffles ~3, and falls into the troughs 50 beneath the heanh. Any ~huil~ of sand still bound by the organic resin which may become dislodged from the worlcpieces over the rst third of ~he fumace are captured on the screens ~2 over the troughs 50, where they will remain until the heat of the 20furnace burns off uhe rem~inir~ binder. When the remaining binder is bumed off, the clumps of sand will fall apart, and the sand will fall throllgh~the screen 52, impact upon the baffles 53 to further break up the clumps, and fall in~o the trough 50.
The sand which falls into the troughs 5 0 is 25conveyed by the screw conveyers 58 to the common sand conveyer 59, whereby it is transponed to the collection bin 60 for reuse. It will be appreciated that the sand thus recovered is substantially pure, the organic resin having been bumed off during the heat treating process.
30As Ihe workpieces exit the lower end 9~ of the heat treating furnace 11, they are ready for quenching. The water in the quench tank 12 is preheated to a suitable q-lenching temperature. The basket 40 of castings is driven on~o the rack 62 by the powered rollers 64, and the racli is 35submerged in the water within ten seconds after the furnace WO 92/20478 2 i ~ 3 1 ~ ~i PCr/US92/03079 discharge door begins to open. While Ihe wor~;pieces are submerged, the twin propellers 68 agitate the water in the tan};, ~nd the direction vanes direct the flow of water over the workpieces. The turbulent water washes any sand remaining s in the cavity of the workpieces out of the worlcpieces and into the tank 12. The workpieces remain submerged for approximately eight minutes, at the end of which time the pneumatic cylinder is actuated to lift the racl; 62 out of the tank 12. When the workpieces are removed from the quench o tank, subst~rlti~lly all of the rem~ining sand has been removed from the castings. The c~ctin~ are now ready for aging.
Meanwhile, the sand which was washed out of the c~sti~s in the quench tanlc 12 settles into the trough 72 in the bottom of the tank. The screw auger 74 conveys the sand-water slur~ to dle hold~ng area 76, and the double-diaphragm pump 78 moves the slurry onto the vibratory sand unit 80.
The water in the slu~ry p~Cse~ through the vibrating screen and falls into the collector adjacent to the screen. The water thus separated from the sand is conveyed to the holding tank 82 and from there is returned to the quench tank 12. The sand which remains on top of the vibrating screen is tlisch~rged from the screen onto the sand conveyer 59, where it joins sand from the troughs 50 of the furnace ll in route to the reclamation bin 60.
Upon completion of the quenching process, the workpieces are introduced into the aging oven 13. The burners 96 heat the work chamber 8~ of the oven 13 to approximately 450~F. The roller hearth 94 conveys the bas~;et 40 of workpieces slowly through the work chamber 8~ of the oven 13 such that the workpieces are subjected tO the 450~F.
heat of the oven of the disclosed embodiment for a period of about four hours. As previously suggested, the dwell time within the aging oven 13 may range from four to twenty hours, depending upon the particular alloy being used and the 3s metallurgical characteristics desired of the casting. The WO 92~20~8 PCI /US92/03079 , 21031~

circulation of the air within the wor~; chamber 85 by the f~n 92 facilitates uniform heating of the wor};pieces. Any sand which becomes dislodged from the workpieces d~lring the aging procedure will settle into the troughs 98 in the boltom of the oven 13. The emergence of the workpieces from the aging oven 13 signals the end of the heat treating and aging process.
As will be appreciated from tl~e foregoing description of the operation of the apparatus 10, a primary feature of the present invention is the combustion of the phenolic resin binding the sand core by exposing the casting and core to the heat of the furnace 11. It has been found that the major portion of such combustion occurs in lhe second and third of the eight 7O'~S; in ~e ~lrst zone 16A, the casting and lS core are being brought up to combustion temperature of 980~F, and in the later zones 16D~H the combustion is subst~nti~lly complete. Accordingly, the burners 1g in zones 16B and 16C are adjusted to provide air in excess of the amounlt required by the burners to ensure that there is suf~lcient oxygen in those zones to facilitate the combustion process. In the disclosed embodiment, the burners 18 in zones 16B and 16C are adjusted to provide 13-17% oxygen. ln the remaining zones 16A and 16D-F, however, the burners 18 are adjusted ~o provide only lO-13% oxygen. Since there is 2s not the extent of excess air which must be heated, the bumers in those zones where less combustion occurs can operate more efficiently than if the same extent of excess air were provided to all zones of the furnace.
The foregoing embodiment has been disclosed with respect to a continuous process, that is, workpieces are continuously being introduced into the apparatus 10, some workpieces thus being in one stage of processing ~ hile other workpieces are at other stages of the process. In this continuous process, some workpieces will be undergoing he:~
3s treating at the same ~ime that other workpieces are being 213313~

quenched and still other wor};pieces are being aged. ln fi~ict, al any given time, there may be baskets of wor~pieces al ~ilrious poin~s within the fumace 11, some only just beginninn the heat treating process while others are further along in the process, s all continuously advancing through thie apparalus. However, it will be appreciated that the present invention is equally well suited for batch processing, where only a single b~tch of materials is undergoing processing at any given timie.
Fig. 6 discloses a batch-type heat t~ tin~
o apparatus 110 according to the present invention. Cer.~ o~
the components of the batch apparatus 110 are i(iientical to components previously described and will be designat~d by th~
same reference numerals previously used. Thus, con pollenls previously described can be reco~ni7e~1 from their design~tioll lS by a reference numeral less thian 100. Thiose components not previously described with reference to the continuous h~a~
tre~tin~ furnace will be designated with reference numer;31s higher than 100.
The apparatus 110 includes an ele~ate~i drop-bottom furnace 111 elevated on legs 114. A lift mechainism 116 powered by pneumatic, hydraulic, or mech~nic~l po~er, is operative to raise and lower workpieces into and out of the furnace 111. In the disclosed embodiment, the lift mechilnisn~
116 includes hooks 1 18 for engaging a bas~et ~0 of workpieces, whereby the entire basket is lifted inlo the furnace. A sliding door 120 in the bottom of the fumace has a pair of sand collection troughs 122 formied therein. Screells 52 positioned over the troughs 122 prevent p~irticles l.lrp~er than one-quarter inch from falling into th~ troughs.
Pneumatically operated high temperature slide gat~s al e selectively operable to discharge sand collected in ~lle trou~h~
122.
As with the continuous furnace 11, the batcll furnace 110 has a ceramic fiber insulating blanket 12~ lo 3s retain heat within the furnace and a metal liner 126 to protec~

WO 92/20478 PCI /US92~03079 21G313~ 22 the ceramic fiber insulation from flying sand. A fan 44 mounted in the top of the furnace circulates the air within the furnace at 3000-5000 feet per minute. Burners 18 mounted in the side walls of the fumace 110 heat the work chamber 130 s of the furnace. The bumers 1~ once again comprise means for introducing 120-160% excess air into the burners, with the result that the environrnent within the furnace comprises 10-12% oxygen.
A pair of tracks 140 runs beneath lhe elevated o furnace 110. A quench tank and transfer car 145 runs along the tracks 140 on wheels 146 and comprises a quench tan~;
148, a sand collection bin 150, and a basket transfer area 152. The car 14S is selectively operable to position eilher the basket transfer area 152, the quench tank 148, or the sand IS collection bin lS0 bene~ the drop-bottom furnace worl~
chq~nber 130.
The quench tank 148 includes a heater for preh~ting the water in the tank to a suitable quenching temperature. A pair of propeller agitators 68 circulate the water in the quench tank. A header 156 in the bottom of the tank has a plurality of openin~s for placing the interior of the tank in ~luid connrnllnication with a vibratory sand dryer ~0.
A double diaphragm pump 78 is selectively operable to pump sand out of the bottom of the q!ler-ch tank 148 and convey i~ to the vibratory sand dryer 80. The operation of the vibratory sand dryer has previously been explained. After the water has been remoYed from the sand by the vibra~ory sand dryer 80, the water is pumped into a holding tank 82, and the sand is conveyed into the sand bin lS0.
The operation of the batch-type fumace 110 will now ~e explained. Castings are formed as previously described and removed from their respective molds. The castings are placed in a basket 4 0, and the basket of workpieces is placed on the basket transfer area 1~2 of the 3s quench tank and transfer car 145. The car 14~ is then moved wo 92/20478 ~ 1 0 3 1 ~ 6 PCI /US92/03079 along its trac~s 140 to position its basket transfer area 152 directly beneath the heated fumace 111. The bot~om door 120 of the fumace is opened, and the lift mechanism 116 is lowered so that the hooks 118 of the lift mechanism enga~e s the basket 40. The lift mech~-lism 116 is then actuated to raise the basket 40 of workpieces in~o the work chamber 130 of the furnace 111, and the bottom 120 of the furnace is closed.
The burners 18 heat the load in the work o chamber 130 of the fumace 111 to a temperature of approximately 980~F. Again, however, depending up~n the alloy used and the metallurgical characteristics desired, the workpieces may be heated over a range o~' 850~-1000~F. 120-160% excess air is introduced into the bumers 18 so that the IS resulting atmosphere within the fumace comprises 10-12%
oxygen. The fans 44 operate to circulate the air within the fumace to achieve an airflow of 3000-5000 feet per minute.
As the castings and the cores are heated, the resin binder begins to burn off. Loosened sand is dislodged from the workpieces by the airflow and by force of gravity, and the dislodged sand falls into the troughs 122. Clumps of core mateAal from which the binder component has not completely bumed off will be captured on the screens 52 over the troughs 12~ and retained there until the binder has burned off, at which time the unbonded sand will fall through the screen, tumble down the inverted V-shaped baffles 53, and fall into the troughs. The metal liner 126 protects the interior of the furnace 111 from the abrasive effects of flying sand.
When the workpieces have been heat trea~ed for the desired length of time (six hours in the disclosed embodiment), the burners 18 are shut down. The transfer car 145 is positioned along itS tracks 140 so that the quench tanl;
148 is directly beneath the work chamber 130 of the furnace 111, and the bottom 120 of ~he furnace is opened. The lift 3s mechanism 116 is then actuated to lower the basket 40 of wo 92120478 Pcr/us92/03079 .

~ 1 O,~ ; 24 workpieces into the quench tank 148. The wor};pieces are submerged for the desired length of time, during which period the water in the tank is agitated by the tWih propellers 68 to loosen the rem~ining sand from the castings. Sand thus dislodged from the wor~pieces settles to the bottom of the tan};
148. At the end of the quench sequence, the lift mechanism 116 is again actuated to lift the workpieces out of the tanl;
148. If aging is desired, the furnace 111 is cooled tO abou~ -450~F., the basket is again lihed inlo the work chamber 130, o and the fumace door 120 is closed. The workpieces are then aged for the desired length of time.
Upon completion of the quenching sequence, the transfer car 145 is positioned such ~at the sand collection bin 150 is directly bene~th the slide gates of the sand troughs 122.
The gates are opened, and the collected sand is discharged from the troughs into the sand collection bin. Again, the sand thus recovered is in a clean, reusable state, all of the binder material having been burned of~ by the heat of the furnace.
It will be appreciated by those skilled in the art tbat the provision of a high speed airflow within the wor}~
chamber 1~ of the fumace 11 will result in abrasive particles of sand being blown about the interior of the furnace at high velocities. The disclosed embodiments therefore include special precautions for preventing excessive abrasion and dama~e to the interior of the fumace. The interior walls of the furnace, for example, are provided with l l gauge liners comprised of a 4l30 alloy to resist abrasion~ Also, the fans 4 include features designed to withstand the abrasive ~nvironment wilhin the work chambers 15. For example, the blades of the fans 4 4 are of solid, rather than hollow, construction, as it has been found that flying sand particles can wear holes in hollow blades, especially along seams, and acc~ te within the blades. Even a small accumulation of sand within the hollow blades can throw the fan 44 out of b~l~nce and cause catastropkic damage to the fan drive wo 92/20478 ~ 1 0 3 1 3 6 PC'r/US92/03079 mechanism. As another precaution, the leading edges of the blades of the fans 44 are tapered to deflect sand particles.
It will be appreciated that the present invention offers significant advantages over prior art methods and s apparatus for processing sand castings. First, the requirement of removing a subst~ti~l portion of the core material prior to heat treating the casting has been elimin~ted. Consequently, the labor, equipment, expense, and risk of damage or scarring to the workpiece associated with manually chiseling out ~he o sand core or subjecting the workpiece to agitation and vibration have been elin in~te~
Funher, by subjecting the sand core material to the heat and airflow within the furnace, the resin binder fusing, the core sand is bumed off. To cnsure that substantially all of IS d e binder is comb~lsted, the screens 52 prevent chunlcs of core material larger than a predetennine~l size from falling out of the furnace and retain such ch~mks within the wor~; chamber 15 until a sufficient amount of binder has burned off that the chunk can disintegrate and pass through the screen. Chunks of material which are sufficiently srnall to pass through the screen 52 will impact upon the inverted V-shaped baffles 53 and tumble down the sloped walls of the baffles, further rlisintegrating the material into its individual particles of sand.
Thus, the sand is recovered ir~ a clean, reusable state.
While the recovered sand is clean in the sense that the binder materials have been bumed off, the requirements of a parlicular installation may dictate certain additional processing of the sand before it can be reused. For example, i~
may be desirable to screen the reclaimed sand to reclassify the sand and tO remove any debris which may have become in~elmixed with the sand.
To facilitate combu~tion of binder material from chunks of sand retained on the screens 52, the fumace 11 of the disclosed embodirnent ensures a continuous airflow of 3s oxygenated air over the screens, as indicated by the arrows in ~"::, "", ~ ~",.

W O 92/20478 P ~ /US92/03079 .

- 2 1 0 3 1 3 ~ 26 FIG. 3. To accomplish the desired airflow pattern, the dimension of the gap 56 between the lower end 55 of the walls 54 of the duct 46 is kept to a minimum so as not to provide an airflow path around the lower end of the wall and s above the roller hearth 34. The air flowing downwardly through the ducts 46 must therefore follow a path downward between the rollers 36 and across the screens 52 before it can retum upward between the outer surface of the duct and the liner 32 of the fumace.
A further advantage of the present invention is that since the binder component is combusted, the ecological problems associated with disposal of solid waste material are avoided. If the exhaust gases include ar~ unacceptable quantity of organics or phenils, additional incineration of the exhaust IS gases may be n~cess~ry. In such an inst~rlce~ the exhaust gases upon exiting the preheat ch~mber can be delivered to an inline incinerator operating at a temperature of 1400~-1450~F. to incinerate the free organics or phenils.
The control of the oxygen content of the fumace atmosphere in the disclosed embodiment also affords certain adYantages wi~h respect ~o buming off the resin binder. By introducing excess air into the bumers ~ only those zones of the fumace where the ma~or ponion of the combustion proeess occurs, a 10-12% oxygen level within those zo.~es of the furnace i~ maintained. This level of oxygen facilitates the combustion of the organic resin binder which fuses the core, thereby accelerating the breakdown of the binder and promoting effeclive combustion of the waste products.
However, since the burners in the remaining zones are not adjusted to deliver the extreme amount of excess air required in those zones where the major portion of the combustion process takes place, the bumers are able to operate at increased efficiency.
The invention hereinabove described has been 3s disclosed with respect to a furnace utilizing natural gas ~i~3136 bumers as the heat source. However, it will be understood that the nature of the heating means is not crilical, and other types of heating systems, such as propane burners, indirect gas-fired radiant heaters, electric heaters, oil-fired bumers, or s coal-fired burners, may be employed. ~t will be appreciated that when indirect gas-fired radiant heaters or electric heat are employed, an air injection system should be used to maintain the oxygen level within the fumace at the desired 10-12%
level.
Also, while the disclosed embodiment is an eight zone furnace, the major portion of the binder combustion occurring in the second and third zones, it will be understood that a greater or sn~ller number of zones may be defined within the furnace. In such an instance, the precise zones s within which the major portion of the binder combustion occurs may vary according to a variely of factors, including without li~it~ion the temperature within the fumace, ~he size and confilguration of dle c~tirl~s and cores, the speed at which the castings are moved through the furnace, and the te~ e-ature of the castings when they are introduced into the fumace.
Finally, it will be understood that the preferred embodiment has been disclosed by way of example, and Ihat other modifications may occur tO those skilled in the art 2s without departing from the scope and spirit of the appended claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for heat treating a casting having a sand core, the sand core comprising, at least, sand particles bound together by a binder material, and the sand core defining a cavity within the casting, the method comprising the steps of:
introducing the metal casting, with the sand core therein, into a furnace;
heating the furnace to a temperature in excess of the combustion temperature of the binder material;
providing an oxygenated atmosphere within the heated furnace;
containing the metal casting, with the sand core therein, within the heated furnace in the oxygenated atmosphere to permit the binder material to combust, whereby sand particles of the sand core are loosened from the sand core;
removing the loosened sand particles from the cavity;
capturing clumps of sand core material which become dislodged from the casting prior to the binder material being combusted therefrom; and retaining the dislodged clumps of sand core material within the furnace to permit the binder material to be combusted therefrom.

2. The method of claim 1, wherein the step of removing the loosened sand particles from the cavity includes, at least, continuously removing the loosened sand particles from the cavity as the binder material is combusted.

3. The method of claim 1, wherein the step of removing the loosened sand particles from the cavity includes, at least, directing a flow of air against the casting as the casting is contained within the furnace such that the flow of air dislodges loosened sand particles from the cavity.

4. The method of claim 3, wherein the step of directing a flow of air against the casting as the casting is contained within the furnace includes, at least, a step of directing a flow of air against the casting at an airflow velocity in excess of 3,000 feet per minute.

5. The method of claim 1, further comprising a step of collecting the portion of the sand particles dislodged from the casting and conveying it out of the furnace.

6. The method of claim 5, wherein the step of collecting the portion of the sand particles dislodged from the casting includes, at least, the step of continuously collecting portions of the sand particles as the portions of the sand particles are dislodged from the casting and conveying the portions of the sand particles out of the furnace.

7. The method of claim 1, wherein the step of heating the furnace includes, at least, heating the furnace to a temperature in excess of approximately 850°F.

8. The method of claim 1, wherein the steps of capturing and retaining the dislodged clumps of sand core material include, at least, a step of providing a screen disposed beneath the casting, the screen having openings therein which are not sufficiently large to pass clumps of sand core material of predetermined size.

9. The method of claim 8, further comprising a step of causing clumps of sand core material smaller than the predetermined size which pass through the screen to impact upon a surface so as to break up the clumps.

10. A method for heat treating a casting having a sand core which comprises, at least, sand particles bound together by a binder material, the sand core defining a cavity within the casting, and the method comprising the following steps:
introducing the casting with at least a portion of sand core therein into a furnace;
heating the furnace to a temperature in excess of the combustion temperature of the binder material;
providing an oxygenated atmosphere within the furnace;
containing the casting, with the sand core therein, within the oxygenated atmosphere in the heated furnace to permit the binder material to combust, whereby portions of the sand core are loosened from the sand core and fall from the cavity while the casting is in the furnace; and suspending, within the oxygenated atmosphere in the furnace, portions of the sand core which become dislodged from the casting prior to the binder being combusted therefrom; and releasing the suspended portions of the sand core once the binder is combusted therefrom.

11. A method for heat treating a casting having a sand core which comprises, at least, sand particles bound together by a binder material, the sand core defining a cavity within the casting, and the method comprising the following steps:
introducing the casting with at least a portion of sand core therein into a furnace;
heating the furnace to a temperature in excess of the combustion temperature of the binder material;
providing an oxygenated atmosphere within the furnace;
containing the casting, with the sand core therein, within the oxygenated atmosphere in the heated furnace to permit the binder material to combust, whereby portions of the sand core are loosened from the sand core and fall from the cavity while the casting is in the furnace; and providing a screen disposed beneath the casting and within the oxygenated atmosphere of the furnace, wherein the screen has openings therein which are not sufficiently large to pass portions of the sand core of a predetermined size, and wherein the openings are sufficiently large to pass portions of the sand core which are less than the predetermined size; and suspending on the screen portions of the sand core which are larger than the predetermined size, to allow further combustion of binder material therefrom.

12. The method of claim 11, further comprising the step of releasing the suspended portions of the sand core once the binder is combusted therefrom.

13. The method of claim 11, further comprising, at least, a step of causing portions of the sand core which pass through the screen to impact upon a surface so as to break up the portions of the sand core which pass through the screen.

14. The method of claim 11, further comprising a step of directing airflow against the casting, while the casting is in the furnace, so as to dislodge portions of the sand core from the casting.

15. The method of claim 14, wherein the step of directing airflow against the casting, while the casting is in the furnace, includes, at least, directing, from a plurality of directions, airflow against the casting so as to dislodge portions of the sand core from the casting.

16. The method of claim 14, wherein the step of directing airflow against the casting, while the casting is in the furnace, includes, at least, directing airflow against the casting at an airflow velocity in excess of 3,000 feet per minute.

17. The method of claim 11, wherein the step of providing an oxygenated atmosphere within the furnace comprises, at least, the step of controlling the oxygen content in the furnace so that a higher percent of oxygen is maintained where a higher percentage of the binder material combusts.

18. The method of claim 17, wherein the step of providing an oxygenated atmosphere within the furnace includes, at least, conveying the casting through a plurality of zones within the furnace, controlling the oxygen content within the furnace to provide 13-17% oxygen in zones of the plurality of zones in which a major portion of binder combustion takes place, and controlling the oxygen content within the furnace to provide 10-13% oxygen in zones of the plurality of zones in which a major portion of binder combustion does not take place.

19. The method of claim 11, further comprising the steps of collecting and conveying the loosened portions of sand core out of the furnace.

20. The method of claim 11, wherein the step of heating the furnace includes, at least, heating the furnace to a temperature of approximately 980°F.

21. A method for manufacturing a casting comprising the following steps:
producing a casting having a sand core, wherein the sand core includes, at least, sand particles bound together by a combustible binder material, and wherein the sand core defines a cavity within the casting;
introducing the casting into a furnace prior to any substantial destruction to the sand core, wherein the furnace is heated to a temperature in excess of the combustion temperature of the binder material;
providing an oxygenated atmosphere within the furnace;
containing the casting, with the sand core therein, within the furnace to permit the binder material to combust, whereby sand particles of the sand core are loosened from the sand core and fall from the cavity while the casting is in the furnace; and suspending, within the oxygenated atmosphere in the furnace, portions of the sand core which become dislodged from the casting prior to the binder being combusted therefrom; and releasing the suspended portions of the sand core once the binder is combusted therefrom.

22. The method of claim 21, wherein the step of introducing the casting into the furnace is performed prior to any mechanical shaking intended to remove meaningful portions of the sand core, whereby mechanical shaking for core removal is avoided.

23. A method for heat treating a casting having a sand core which comprises, at least, sand particles bound together by a binder material, the sand core defining a cavity within the casting, and the method comprising the following steps:
introducing the casting with at least a portion of sand core therein into a furnace, wherein the furnace defines a plurality of zones that are spatially displaced from one another;
heating the furnace to a temperature in excess of the combustion temperature of the binder material;
providing an oxygenated atmosphere in at least one zone of the plurality of zones;
conveying the casting along a path through the plurality of zones, whereby the casting, with the sand core therein, is exposed to the oxygenated atmosphere within the heated furnace to permit the binder material to combust, whereby portions of the sand core are loosened from the sand core and fall from the cavity while the casting is in the furnace;
suspending, within the oxygenated atmosphere in the furnace, portions of the sand core which become dislodged from the casting prior to the binder being combusted therefrom; and releasing the suspended portions of the sand core once the binder is combusted therefrom.

24. The method of claim 23, wherein the step of introducing the casting into the furnace is performed prior to any mechanical shaking intended to remove substantial portions of the sand core, whereby mechanical shaking for core removal is avoided.

25. The method of claim 24, further comprising the steps of:
providing a screen disposed beneath the casting and within the oxygenated atmosphere of the furnace, wherein the screen has openings therein which are not sufficiently large to pass portions of the sand core of a predetermined size, and wherein the openings are sufficiently large to pass portions of the sand core which are less than the predetermined size; and suspending on the screen portions of the sand core which are larger than the predetermined size, to allow further combustion of binder material therefrom.

26. The method of claim 23, further comprising the steps of:
providing a screen disposed beneath the casting and within the oxygenated atmosphere of the furnace, wherein the screen has openings therein which are not sufficiently large to pass portions of the sand core of a predetermined size, and wherein the openings are sufficiently large to pass portions of the sand core which are less than the predetermined size; and suspending on the screen portions of the sand core which are larger than the predetermined size, to allow further combustion of binder material therefrom.

27. The method of claim 26, further comprising, at least, a step of causing portions of the sand core which pass through the screen to impact upon a surface so as to break up the portions of the sand core which pass through the screen.

28. The method of claim 23, further comprising a step of directing airflow against the casting, while the casting is in the furnace, so as to dislodge portions of the sand core from the casting.

29. The method of claim 28, wherein the step of directing airflow against the casting, while the casting is in the furnace, includes, at least, directing, from a plurality of directions, airflow against the casting so as to dislodge portions of the sand core from the casting.

30. The method of claim 23, wherein the step of providing an oxygenated atmosphere further includes, at least, controlling the oxygen content within the furnace to provide 13-17% oxygen in the zones of the plurality of zones in which a higher percentage of the binder material combusts, and controlling the oxygen content within the furnace to provide 10-13% oxygen in the zones of the plurality of zones in which a lesser percentage of the binder material combusts.

31. The method of claim 23, further comprising the step of angling the casting within the furnace such that at least a portion of the loosened portions of the sand core will fall out of the casting under the force of gravity.

32. The method of claim 23, further comprising the steps of collecting and conveying the loosened portions of sand core out of the furnace.

33. The method of claim 23, wherein the step of heating the furnace includes, at least, heating the furnace to a temperature of approximately 980°F.

34. A method for manufacturing a casting comprising the following steps:
producing a casting having a sand core, wherein the sand core includes, at least, sand particles bound together by a combustible binder material, and wherein the sand core defines a cavity within the casting;
introducing the casting with at least a portion of sand core therein into a furnace, wherein the furnace is heated to a temperature in excess of the combustion temperature of the binder material, and wherein the furnace defines a plurality of zones that are spatially displaced from one another;
providing an oxygenated atmosphere in at least one zone of the plurality of zones;
conveying the casting along a path through the plurality of zones, whereby the casting, with the sand core therein, is exposed to the oxygenated atmosphere within the heated furnace to permit the binder material to combust, whereby portions of the sand core are loosened from the sand core and fall from the cavity while the casting is in the furnace; and suspending, within the oxygenated atmosphere in the furnace, portions of the sand core which become dislodged from the casting prior to the binder being combusted therefrom; and releasing the suspended portions of the sand core once the binder is combusted therefrom.

35. The method of claim 34, wherein the step of introducing the casting into the furnace is performed prior to any mechanical shaking intended to remove substantial portions of the sand core, whereby mechanical shaking for core removal is avoided.

36. The method of claim 34, further comprising the steps of:
providing a screen disposed beneath the casting and within the oxygenated atmosphere of the furnace, wherein the screen has openings therein which are not sufficiently large to pass portions of the sand core of a predetermined size, and wherein the openings are sufficiently large to pass portions of the sand core which are less than the predetermined size; and suspending on the screen portions of the sand core which are larger than the predetermined size, to allow further combustion of binder material therefrom.

37. The method of claim 36, further comprising a step of causing portions of the sand core which pass through the screen to impact upon a surface so as to break up the portions of the sand core which pass through the screen.

38. The method of claim 34, further comprising a step of directing airflow against the casting, while the casting is in the furnace, so as to dislodge portions of the sand core from the casting.

39. The method of claim 38, wherein the step of directing airflow against the casting, while the casting is in the furnace, includes, at least, directing, from a plurality of directions, airflow against the casting so as to dislodge portions of the sand core from the casting.

40. The method of claim 38, wherein the step of directing airflow against the casting, while the casting is in the furnace, includes, at least, directing airflow against the casting at an airflow velocity in excess of 3,000 feet per minute.

41. The method of claim 34, wherein the step of providing an oxygenated atmosphere further includes, at least, controlling the oxygen content within the furnace to provide 13-17% oxygen in the zones of the plurality of zones in which a higher percentage of the binder material combusts , and controlling the oxygen content within the furnace to provide 10-13% oxygen in the zones of the plurality of zones in which a lesser percentage of the binder material combusts.

42. The method of claim 34, further comprising steps of collecting and conveying the loosened portions of sand core out of the furnace.

43. The method of claim 34, wherein the step of heating the furnace includes, at least, heating the furnace to a temperature of approximately 980°F.

44. A method for heat treating a casting having a sand core which comprises, at least, sand particles bound together by a binder material, the sand core defining a cavity within the casting, and the method comprising the following steps:
introducing the casting, with the sand core therein, into a furnace;
heating the furnace to a temperature in excess of the combustion temperature of the binder material;
providing an oxygenated atmosphere within the furnace;
containing the casting, with the sand core therein, within the oxygenated atmosphere in the heated furnace to permit binder material to combust, whereby portions of the sand core are loosened from the sand core and fall from the cavity while the casting is in the furnace; and suspending within the oxygenated atmosphere in the furnace portions of the sand core that have fallen from the casting.

45. The method of claim 44, wherein the step of suspending includes, at least, capturing at least some of the portions of the sand core that have fallen from the casting, retaining the captured portions of the sand core within the furnace in a manner that permits binder material to be combusted therefrom, and releasing the retained portions of the sand core subsequent to the combustion of binder material therefrom.

46. The method of claim 45, wherein the furnace defines a plurality of zones that are spatially displaced from one another, and wherein the method further comprises the step of conveying the casting along a path through the plurality of zones.

47. An apparatus for heat treating a metal casting having a sand core comprising sand bound by a binder, wherein the sand core defines a cavity within the casting, and wherein the apparatus comprises:
a work chamber for receiving the casting therewithin;
a heating means for heating an atmosphere within said work chamber such that the casting and the sand core are heated to a temperature sufficient to combust the binder of the sand core, whereby the binder is burned off, so as to dislodge portions of the sand core from the casting; and retaining means operatively associated within said work chamber for capturing portions of the sand core which become dislodged from the casting prior to the binder being combusted therefrom, and retaining the captured portions of the sand core within said work chamber atmosphere, until the binder has been substantially combusted therefrom.

48. The apparatus of claim 47, further comprising collection means formed in a lower portion of said work chamber for collecting the portion of the sand dislodged from the casting, where said retaining means is disposed above said collection means.

49. The apparatus of claim 47 or 48, wherein said retaining means includes, at least, a screen.

50. The apparatus of claim 47 or 48, wherein said retaining means is a broad member defining a plurality of apertures therethrough.

51. The apparatus of claim 48, further comprising hearth means for supporting the casting within said work chamber, wherein said hearth means is disposed above said collection means.

52. The apparatus of one of claims 47-51, wherein said retaining means is constructed and arranged to release captured and retained portions of the sand core once the binder has been substantially combusted therefrom, wherein the released portions of the sand core are reduced to a size smaller than one-quarter inch.

53. The apparatus of claim 48, wherein said collection means includes, at least, a trough.

54. The apparatus of claim 47, further comprising baffle means disposed beneath said retaining means for contacting portions of sand core released from said capturing means.

55. The apparatus of claim 47, further comprising a discharge means for discharging the sand from said collection means and said work chamber.

56. An apparatus for heat treating a casting having a sand core comprising sand bound by a binder, wherein the sand core defines a cavity within the casting, and wherein the apparatus comprises:
a work chamber for receiving the casting therewithin;
a heating means for heating said work chamber such that the casting and the sand core are heated to a temperature sufficient to combust the binder of the sand core, whereby binder is burned and portions of the sand core are dislodged from the costing; and suspension means in heat and gaseous communication with said work chamber fosuspending portions of the sand core and substantially promoting further combustion of the binder of the suspended portions of the sand core.

57. The apparatus of claim 56, wherein said suspension means includes, at least, a screen.

58. The apparatus of claim 56, further comprising baffle means disposed beneath said suspension means for contacting portions of sand core released from said suspension means.

59. The apparatus of claim 58, wherein said suspension means is constructed and arranged to release suspended portions of the sand core once the binder has been substantially combusted therefrom.

60. The apparatus of claim 59, wherein the released portions of the sand core are reduced to a size smaller than one-quarter inch.

61. The apparatus of claim 60, further comprising means for directing airflow over the suspended portions of the sand core so as to promote combustion of the binder therefrom.

62. The apparatus of any one of claims 56-61, further comprising:
hearth means for supporting the casting within said work chamber, wherein said suspension means is disposed below said hearth means.

63. The apparatus of claim 56, wherein said suspension means is disposed within said work chamber.

64. The apparatus of claim 63, further comprising collection means formed in a lower portion of said work chamber for collecting portions of the sand core dislodged from the casting, wherein said suspension means is disposed above said collection means.

65. The apparatus of claim 64, further comprising a hearth means for supporting the casting within said work chamber, wherein said hearth means is disposed above said collection means and said suspension means is interposed between said hearth means and said collection means.

66. The apparatus of claim 65, wherein said suspension means, said hearth means, and said collection means are vertically aligned.

67. The apparatus of claim 66, further comprising a discharge means for discharging the sand from said collection means and said work chamber.

68. A method for heat treating a casting having a sand core which comprises, at least, sand particles bound together by a binder material, the sand core defining a cavity within the casting, and the method comprising the following steps:
providing a flow of oxygenated air;
heating the flow of oxygenated air to a temperature in excess of the combustion temperature of the binder material;
introducing the casting into a furnace, wherein the casting is exposed within the furnace to the flow of oxygenated and heated air to permit binder material to combust, whereby portions of the sand core are loosened from and fall from the cavity of the casting while the casting is within the furnace;
collecting, distant from the casting, the portions of the sand core which fall from the cavity of the casting prior to the binder being combusted therefrom;
maintaining the collected portions of the sand core within the flow of oxygenated air to permit binder to be combusted therefrom, whereby the flow of oxygenated air is heated and sand is at least partially reclaimed from the collected portions of the sand core; and conveying the at least partially reclaimed sand away from the furnace.

69. The method of claim 68, wherein the step of maintaining the collected portions of sand core within the flow of oxygenated air includes, at least, suspending the collected portions of sand core within the flow of oxygenated air to permit binder to be combusted therefrom.

70. The method of claim 69, wherein any clumps of portions of sand core transported away from the furnace with the at least partially reclaimed sand have been disintegrated to a size smaller than one-quarter inch.

71. The method of claim 69, wherein the step of suspending the collected portions of sand core is carried out within the furnace.

72. The method of claim 71, wherein the step of suspending includes, at least, providing a screen disposed beneath the casting and within the furnace,suspending on the screen portions of the sand core which are larger than a predetermined size, to allow further combustion of binder material therefrom, and releasing the suspended portions of the sand core subsequent to the combustion of binder therefrom.

73. The method of claim 69, wherein the furnace defines a plurality of zones that are spatially displaced from one another, and wherein the method further comprises the steps of, conveying the casting along a path through the plurality of zones, and directing the flow of oxygenated air from a plurality of directions against the casting, while the casting is in the furnace, so as to dislodge portions of the sand core from the casting, wherein the step of directing airflow includes, at least, directing a flow of air in a first direction in a first zone of the plurality of zones, and directing a flow of air in a second direction in a second zone of the plurality of zones, and wherein the step of conveying includes, at least, conveying the casting sequentially through the first zone and the second zone.

74. A method for heat treating a casting having a sand core which comprises, at least, sand particles bound together by a binder material, the sand core defining a cavity within the casting, and the method comprising the following steps:
introducing the casting into a furnace, wherein the furnace defines a plurality of zones that are spatially displaced from one another;
heating the furnace to a temperature in excess of the combustion temperature of the binder material;
providing an oxygenated atmosphere in at least one zone of the plurality of zones;
conveying the casting along a path through the plurality of zones, whereby the casting, with the sand core therein, is exposed to the oxygenated atmosphere within the heated furnace to permit the binder material to combust;
directing airflow at the casting while the casting is in the furnace so as to dislodge portions of the sand core from the casting, wherein the step of directing airflow includes, at least, varying the direction from which airflow is directed at the casting as the casting is conveyed through the furnace; and suspending, within the oxygenated atmosphere in the furnace, portions of the sand core which become dislodged from the casting prior to the binder being combusted therefrom such that binder is combusted from the suspended portions of the sand core.

75. The method of claim 74, Wherein the step of varying the direction from which airflow is directed at the casting includes, at least, directing a flow of air in a first direction in a first zone of the plurality of zones, and directing a flow of air in a second direction in a second zone of the plurality of zones, and wherein the step of conveying includes, at least, conveying the casting sequentially through the first zone and the second zone.

76. The method of claim 75, wherein the step of varying the direction from which airflow is directed at the casting includes, at least, operating a fan in each of the first zone and the second zone, and providing ductwork in each of the first zone and the second zone such that the direction of airflow in the first zone differs from the direction of airflow in the second zone.

77. The method of claim 75, wherein the step of directing a flow of air against the casting as the casting is contained within the furnace includes, at least, a step of directing a flow of air against the casting at an airflow velocity in excess of 3,000 feet per minute.

78. The method of claim 75, wherein the step of varying the direction from which airflow is directed at the casting further includes, at least, directing a flow of air horizontally through a third zone of the plurality of zones, wherein the step of conveying further includes, at least, conveying the casting through the third zone, and wherein the first direction and the second direction are vertical directions.

79. A method of processing a casting having a sand core, which sand core comprises, at least, sand particles bound together by a binder material, which sand core defines a cavity within the casting, the method comprising the steps of:
introducing a casting with at least some sand core therein into a furnace;
heating the furnace to a temperature sufficient to heat treat the casting and sufficient to combust the binder of the sand core;
burning binder of the sand core within the furnace to release core portions of varying sizes from the casting;
reducing the size of at least larger portions of the released sand core portion within the furnace, which reducing is accomplished through additional burning of binder in the larger portions of the released sand core portions; and thereafter conveying sand and any attached binder away from the furnace, thereby accomplishing heat treatment, core removal, and at least partial sand reclamation in an integrated process associated with a single furnace.

80. The method of claim 79, wherein the step of introducing the casting into the furnace is performed prior to any mechanical shaking intended to remove substantial portions of the sand core, whereby mechanical shaking for core removal is avoided.

81. The method of claim 79, further comprising the steps of:
conveying the casting along an elongated path through a plurality of adjacent zones, wherein the path and the plurality of adjacent zones are defined by the furnace; and cooling the casting at some point in time after the casting has been conveyed through the plurality of adjacent zones; and wherein the heating step includes, at least, the step of heating all zones of the plurality of adjacent zones; and wherein the burning step includes, at least, the steps of introducing oxygen to zones of the plurality of adjacent zones and controlling the introduction of oxygen to introduce larger amounts of oxygen in certain zones encountered by the casting and smaller amounts of oxygen in the zones encountered by the casting later than said certain zones, whereby core portions in varying amounts and varying sizes are released in more than one zone of the plurality of adjacent zones.

82. The method of claim 81, wherein the reducing step includes, at least, the step of reexposing the larger portions of the released sand core portions to heated and oxygenated air associated with at least one of the zones of the plurality of adjacent zones.

83. The method of claim 81, wherein the method further comprises a step of directing airflow from a plurality of directions against the casting, while the casting is in the furnace, so as to dislodge portions of the sand core from the casting, wherein the step of directing airflow includes, at least, directing a flow of air in a first direction in a first zone of the plurality of zones, and directing a flow of air in a second direction in a second zone of the plurality of zones, and wherein the step of conveying includes, at least, conveying the casting sequentially through the first zone and the second zone.

84. A method for heat treating a casting having a sand core which comprises, at least, sand particles bound together by a binder material, the sand core defining a cavity within the casting, and the method comprising the following steps:
providing an oxygenated atmosphere;
heating the oxygenated atmosphere to a temperature in excess of the combustion temperature of the binder material;
introducing the casting, with at least a portion of the sand core therein, into a furnace, wherein the furnace includes a support assembly for supporting the casting within the furnace, wherein the introducing step includes a step of placing the casting upon the support assembly, wherein the casting is exposed within the furnace to the oxygenated and heated atmosphere to permit binder material to combust, and wherein portions of the sand core are loosened from and fall from the cavity of the casting and the support assembly while the casting is within the furnace;
collecting, distant from the casting and the support assembly, the portions of the sand core which fall from the support assembly prior to the binder being combusted therefrom;
maintaining the collected portions of the sand core within the oxygenated atmosphere in a manner that permits binder to be combusted therefrom such that sand is at least partially reclaimed from the collected portions of the sand core; and conveying the at least partially reclaimed sand away from the furnace.

85. The method of claim 84, wherein the step of maintaining the collected portions of the sand core within the oxygenated atmosphere includes a step of suspending the collected portions of the sand core within the oxygenated atmosphere to permit binder to be combusted therefrom.

86. The method of claim 85, wherein the maintaining step includes a step of sizing the collected portions of the sand core and any clumps of portions of the sand core transported away from the furnace with the at least partially reclaimed sand have been disintegrated to a size smaller than one-quarter inch.

87. The method of claim 85 or 86, wherein the step of suspending the collected portions of the sand core is carried out within the furnace.

88. The method of claim 85, wherein the step of suspending includes steps of providing a screen disposed beneath the casting and within the furnace, suspending on the screen portions of the sand core which are larger than apertures defined by the screen, to allow further combustion of binder material therefrom, and releasing the suspended portions of the sand core subsequent to the combustion of binder therefrom.

89. The method of claim 88, wherein the released portions of the sand core fall into a hopper disposed within the furnace.

90. The method of claim 85, wherein the furnace defines a plurality of zones that are spatially displaced from one another, and wherein the method further comprises a step of conveying the casting along a path through the plurality of zones

91. The method of claim 90, wherein the method further comprises a step of directing the oxygenated atmosphere from a plurality of directions against the casting, while the casting is in the furnace, so as to dislodge portions of the sand core from the casting, wherein the directing step includes steps of directing a flow of air in a first direction in a first zone of the plurality of zones, and directing a flow of air in a second direction in a second zone of the plurality of zones, and wherein the step of conveying includes a step of conveying the casting sequentially through the first zone and the second zone.

92. A method of processing a casting having a sand core, which sand core comprises, at least, sand particles bound together by a binder material, which sand core defines a cavity within the casting, the method comprising steps of:
introducing a casting with at least some sand core therein into a furnace, wherein the furnace includes a support assembly for supporting the casting within the furnace, and wherein the introducing step includes a step of placing the casting upon the support assembly;
heating the furnace to a temperature sufficient to heat treat the casting and sufficient to combust the binder of the sand core;
burning binder of the sand core within the furnace to release core portions of varying sizes from the casting, wherein the released sand core portions fall from the cavity of the casting and the support assembly while the casting is within the furnace;
reducing, at a reclaiming region distant from the casting and the support assembly, the size of at least larger portions of the fallen sand core portions to at least partially reclaim sand from larger portions of the fallen sand core portions, which reducing is accomplished through additional burning of binder in the larger portions of the released sand core portions, and wherein the reclaiming region and the furnace are proximately located such that heat passes between the reclaiming region and the furnace; and thereafter conveying sand and any attached binder away from the furnace, thereby accomplishing heat treatment, core removal, and at least partial sand reclamation in an integrated process associated with a single furnace.

93. The method of claim 92, wherein gasses are transferred between the reclaiming region and the furnace.

94. The method of claim 92, wherein the method further comprises a step of maintaining the larger portions of the released sand core portions in a heated state during the time between the step of burning binder and the step of reducing.

95. The method of claim 92, wherein the step of reducing is carried out prior to any activity intended to substantially cool the larger portions of the released sand core portions.

96. The method of claim 92, wherein the reclaiming region is below the support assembly such that the released sand core potions fall, under the force of gravity, from the support assembly to the reclaiming region.

97. The method of claim 96, wherein the reclaiming region is disposed within the furnace.

98. The method of claim 97, wherein the reducing step includes a step of suspending upon a screen disposed within the heated atmosphere of the furnace at least the larger portions of the fallen sand core portions.

99. The method of claim 92, further comprising steps of:
conveying the casting along an elongated path through a plurality of adjacent zones, wherein the path and the plurality of adjacent zones are defined by the furnace; and cooling the casting at some point in time after the casting has been conveyed through the plurality of adjacent zones; and wherein the heating step includes a step of heating all zones of the plurality of adjacent zones; and wherein the burning step includes steps of introducing oxygen to zones of the plurality of adjacent zones, and controlling the introduction of oxygen to introduce larger amounts of oxygen in certain zones, and smaller amounts of oxygen in those zones encountered by the casting later than said certain zones, whereby core portions in varying amounts and varying sizes are released in more than one zone of the plurality of adjacent zones.

100. The method of claim 99, wherein the reducing step includes a step of reexposing the larger portions of the released sand core portions to heated and oxygenated air associated with at least one of the zones of the plurality of adjacent zones.

101. The method of claim 91, wherein the method further comprises a step of directing airflow from a plurality of directions against the casting, while the casting is in the furnace, so as to dislodge portions of the sand core from the casting, wherein the step of directing airflow includes steps of directing a flow of air in a first direction in a first zone of the plurality of zones, and directing a flow of air in a second direction in a second zone of the plurality of zones, and wherein the step of conveying includes a step of conveying the casting sequentially through the first zone and the second zone.

102. A method for heat treating a casting having a sand core and reclaiming sand from the sand core, wherein the sand core comprises sand particles bound together by a binder material, the sand core defining a cavity within the casting, and the method comprising the following steps:
introducing the casting, with at least a portion of the sand core therein, into a furnace system containing an oxygenated and heated atmosphere, wherein the furnace system defines a heat treating region, and a reclaiming region disposed below the heat treating region and in heat and gaseous communication with the heat treating region, wherein the furnace system includes a support assembly for supporting the casting within the heat treating region, and wherein the introducing step includes a step of placing the casting upon the support assembly;
heat treating the casting while the casting is disposed within the heat treating region;
dislodging portions of the sand core from the casting while the casting is disposed within the heat treating region, wherein the dislodging step includes a step of combusting binder material of the portions of the sand core, and wherein the dislodged portions of the sand core fall from the casting and the support assembly into the reclaiming region;
reclaiming, at least partially and within the reclaiming region, sand from the fallen portions of the sand core, wherein the reclaiming step includes a step of further combusting binder material of the fallen portions of the sand core; and conveying the reclaimed sand away from the furnace system, thereby accomplishing heat treatment, core removal, and at least partial sand reclamation in an integrated process associated with a single furnace system.

103. The method of claim 102, wherein the method further comprises a step of maintaining the released sand core portions in a heated state during the time between the dislodging step and the reclaiming step.

104. The method of claim 102, wherein the step of reclaiming is carried out prior to any activity intended to substantially cool the dislodged portions of the sand core.

105. The method of claim 102, wherein the heat treating region and the reclaiming region are vertically aligned.

106. The method of claim 102, wherein the dislodged portions of the sand core free fall from casting and the support assembly into the reclaiming region.

107. The method of claim 102, wherein the heat treating region and the reclaiming region are both disposed within a single furnace.

108. The method of claim 102, wherein the combusting step of the dislodging step includes a step of exposing the casting and at least a portion of the sand core therein to the oxygenated and heated atmosphere.

109. The method of one of the claims 102-108, wherein the further combusting step of the reclaiming step includes a step of suspending, within the oxygenated and heated atmosphere, at least some of the fallen portions of the sand core such that binder is combusted from the suspended portions of the sand core.

110. A method for heat treating a casting having a sand core which comprises sand particles bound together by a combustible binder material, the sand core defining a cavity within the casting, and the method comprising steps of:
introducing the casting, with at least a portion of the sand core therein, into a furnace;
heating the furnace to a temperature sufficient to heat treat the casting and in excess of the combustion temperature of the binder material;
providing an oxygenated atmosphere in the furnace, whereby the casting and the sand core therein are exposed to the oxygenated atmosphere within the heated furnace to permit binder material of the sand core to combust;
directing airflow at the casting while the casting is in the furnace so as to dislodge portions of the sand core from the casting, wherein the directing step includes a step of varying the direction from which airflow is directed at the casting while the casting is in the furnace; and suspending, within the oxygenated atmosphere of the furnace, the fallen portions of the sand core.

111. The method of claim 110, further comprising steps of supporting the casting upon a support assembly within the furnace, wherein the dislodged portions of the sand core fall from the casting and the support assembly, and forcing the oxygenated atmosphere to flow across the suspended portions of the sand core, whereby combustion of the binder material of the suspended portions of the sand core is enhanced.

112. The method of claim 111, further comprising a step of releasing the suspended portions of the sand core subsequent to the combustion of binder material therefrom.

113. The method of claim 110, wherein the furnace defines a plurality of zones that are spatially displaced from one another, and wherein the method further comprises a step of conveying the casting along a path through the plurality of zones.

114. The method of claim 113, wherein the step of varying the direction from which airflow is directed at the casting includes steps of directing a flow of air in a first direction in a first zone of the plurality of zones, and directing a flow of air in a second direction in a second zone of the plurality of zones, and wherein the step of conveying includes a step of conveying the casting sequentially through the first zone and the second zone.

115. The method of claim 114, wherein the step of varying the direction from which airflow is directed at the casting further includes a step of directing a flow of air horizontally through a third zone of the plurality of zones, wherein the step of conveying further includes a step of conveying the casting through the third zone, and wherein the first direction and the second direction are vertical directions.

116. The method of claim 114, wherein the step of varying the direction from which airflow is directed at the casting includes a step of operating a fan in each of the first zone and the second zone of the plurality of zones.

117. The method of claim 114, wherein the step of varying the direction from which airflow is directed at the casting further includes a step providing ductwork in each of the first zone and the second zone.

118. The method of claim 114, further comprising a step of suspending, within the oxygenated atmosphere in the furnace, portions of the sand core which become dislodged from the casting prior to the binder being combusted therefrom such that binder material is combusted from the suspended portions of the sand core.

119. The method of claim 114, including a step of sizing the suspended portions of the sand core and releasing portions of the sand core smaller than one-quarter inch.

120. The method of claim 114, wherein the step of suspending includes steps of providing a screen disposed beneath the casting and within the oxygenated atmosphere of the furnace, wherein the screen has openings therein which are not sufficiently large to pass portions of the sand core of a predetermined size, and wherein the openings are sufficiently large to pass portions of the sand core which are less than the predetermined size, and suspending on the screen portions of the sand core which are larger than the predetermined size, to allow further combustion of binder material therefrom.

121. The method of claim 110, wherein the predetermined size is one-quarter inch.

122. A method for heat treating a casting having a sand core which comprises sand particles bound together by a binder material, the sand core defining a cavity within the casting, and the method comprising steps of:
introducing the casting, with at least a portion of the sand core therein, into a furnace that defines a plurality of zones that are spatially displaced from one another;
heating at least a plurality of zones of the plurality of zones to a temperature sufficient to heat treat the casting and in excess of the combustion temperature of the binder material;
conveying the casting along a path through the plurality of zones;
providing an oxygenated atmosphere including steps of introducing a larger amount of oxygen into certain zones of the heated plurality of zones, and introducing a smaller amount of oxygen into zones of the heated plurality of zones encountered by the casting later than said certain zones, whereby the casting and the sand core therein are exposed to the oxygenated atmosphere within the heated furnace to permit binder material of the sand core to combust so that portions of the sand core are loosened from the sand core and fall from the cavity while the casting is in the furnace; and suspending within the oxygenated atmosphere of the furnace, the fallen portions of the sand core.

123. The method of claim 112, wherein the step of providing an oxygenated atmosphere further includes steps of controlling the oxygen content within the furnace to provide 13-17% oxygen in the zones of the plurality of zones in which a higher percentage of the binder material combusts , and controlling the oxygen content within the furnace to provide 10-13% oxygen in the zones of the plurality of zones in which a lesser percentage of the binder material combusts.

124. A method for heat treating a casting having a sand core which comprises sand particles bound together by a combustible binder material, the sand core defining a cavity within the casting, and the method comprising steps of:
introducing the casting, with at least a portion of the sand core therein, into a furnace, and placing the casting upon a support assembly within the furnace;
providing an oxygenated atmosphere in the furnace;
heating the oxygenated atmosphere in the furnace to a temperature sufficient to heat treat the casting and in excess of the combustion temperature of the binder material, wherein the casting and the sand core therein are exposed to the heated and oxygenated atmosphere within the furnace so that binder material of the sand core combusts and portions of the sand core fall from the casting and the support assembly; and further reclaiming sand from the fallen portions of the sand core, by further exposing the fallen portions of the sand core to the heated and oxygenated atmosphere, wherein the further reclaiming step includes a step of sizing the fallen portions of the sand core so that any clumps of portions of sand core that are with the reclaimed sand have been disintegrated to a size smaller than one-quarter inch.

25. The method of claim 114, wherein the reclaiming step includes a step of suspending the fallen portions of the sand core within the heated and oxygenated atmosphere.

126. The method of claim 114, wherein the reclaiming step is carried out within the furance.

127. The method of claim 114, further comprising a step of conveying the reclaimed sand away from the furnace, wherein the reclaiming step is carried out such that any clumps of portions of sand core that are conveyed away from the furnace with the reclaimed sand have been disintegrated to a size smaller than one-quarter inch.

128. A method for heat treating a casting having a sand core which comprises sand particiles bound together by a combustible binder material, the sand core defining a cavity within the casting, and the method comprising steps of:
introducing the casting, with at least a portion of the sand core therein, into a furnace;
heating the furnace to a temperature sufficient to heat treat the casting and in excess of the combustion temperature of the binder material;
providing an oxygenated atmosphere in the furnace, whereby the casting and the sand core therein are exposed to the oxygenated atmosphere within the heated furnace to permit binder material of the sand core to combust;
directing airflow, at an airflow velocity in excess of 3,000 feet per minute, at the casting while the casting is in the furnace, whereby portions of the sand core are dislodged from the casting; and suspending, within the oxygenated atmosphere of the furnace, the fallen portions of the sand core.

129. A method for heat treating a casting having a sand core which comprises sand particles bound together by a binder material, the sand core defining a cavity within the casting, and the method comprising steps of:
providing a flow of oxygenated air;
heating the flow of oxygenated air to a temperature in excess of the combustion temperature of the binder material;
introducing the casting into a furnace, wherein the casting is exposed within the furnace to the flow of oxygenated and heated air to permit binder material to combust, whereby portions of the sand core are loosened from and fall from the cavity of the casting while the casting is within the furnace;
collecting, distant from the casting, the portions of the sand core which fall from the cavity of the casting prior to the binder being combusted therefrom;
maintaining the collected portions of the sand core within the flow of oxygenated air to permit binder to be combusted therefrom, whereby sand is at least partially reclaimed from the collected portions of the sand core; and conveying the at least partially reclaimed sand away from the furnace, wherein the maintaining step includes a step of sizing the collected portions of the sand core so that any clumps of portions of sand core transported away from the furnace with the at least partially reclaimed sand have been disintegrated to a size smaller than one-quarter inch.

130. An apparatus for heat treating a casting having a sand core comprising sand bound by a binder, wherein the sand core defines a cavity within the casting, and wherein the apparatus comprises:
a furnace defining a work chamber for receiving the casting therewithin;
a support assembly for supporting the casting within said work chamber;
a heating means for heating said work chamber to a temperature sufficient to combust the binder of the sand core, whereby binder material is burned and portions of the sand core fall from both the casting and the support assembly;
suspension means for suspending within said work chamber portions of the sand core that fall from the casting and the support assembly prior to the binder being combusted therefrom, wherein said suspension means includes a broad member defining apertures therethrough; and airflow means for directing airflow through said apertures and over the suspended portions of the sand core so as to promote combustion of the binder therefrom.