US3144244A - Apparatus for heating foundry sand or similar granular material - Google Patents

Description

Aug. 11 1964 w A HUNTER APPARATUS FOR HEATING FOUNDRY SAND OR 3144244 SIMILAR GRANULAR MATERIAL Filed Feb. 1, 1965 4 Sheets-Sheet 1 M I jfi Z2 v- H O i y 1| I \m; a 200 I may 9 72 I ||I 11 15 4 ILI, i: l

INVENTOR W/L L MM A. HUNTER BY M 4 7' TO/PNE Y W. A. HUNTER APPARATUS FOR HEATING FOUNDRY SAND OR Aug. 11, 1964 3,144,244

SIMILAR GRANULAR MATERIAL 4 Sheets-Sheet 2 Filed Feb. 1, 1963 INVENTOR W/L L MM ,4. HUNTER W Aug. 11, 1964 w. A. HUNTER 3,144,244

APPARATUS FOR HEATING FOUNDRY SAND 0R SIMILAR GRANULAR MATERIAL Filed Feb- 1, 1963 4 Sheets-Sheet 3 7 60 76 7a 76 74 72 a /04 me ma 72 9a I w a I 90 4 i 12%| I 433% ii. 90 3g? I 5- /o4 5;! a 9e 7" 9 3| 94 i //a 2-1;

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INVENTOR. W//. L MM A HUN TER ATTORNEY w. A. HUNTER 3,144,244 APPARATUS FOR HEATING FOUNDRY SAND OR Aug. 11, 1964 I SIMILAR GRANULAR MATERIAL 4 Sheets-Sheet 4 Filed Feb. 1, 1963 INVENTOR. WALL/AM A. HUNTER BY A TTOR/VEY United States Patent 3,144,244 APPARATUS FGR HEATING FOUNDRY SAND 0R SIMELAR GRANULAR MATERIAL William A. Hunter, Morton Grove, IlL, assignor to Pettibone Mulliken Corporation, Chicago, Ill., a corporation of Delaware Filed Feb. 1, 1963, Ser. No. 255,455 17 Claims. (Cl. 263-28) The improved heating apparatus comprising the present invention has been designed for use primarily in connection with the heating of foundry sand prior to introduction of the sand into a mulling machine for the purpose of coating the grains of sand with a resinous bonding medium. Heating the sand prior to coating the grains thereof offers certain advantages, the principal advantage being that the heat radiates from the grains themselves, melts the resin, and effects substantially complete evaporation of the solvent, thus forming smooth resinous coatings on the individual grains of sand. The improved heating apparatus is, however, capable of other uses and may, either with or withut modification as required, be employed for heating dry granular materials other than foundry sand and for purposes other than resin-coating. For example, the apparatus may be employed for heating raw sand or other small aggregate material prior to mixing the same with tar or oil in the road building industry, little or no modification of the apparatus being required for this particular purpose. Under certain circumstances, the improved heating apparatus may, with suitable modification, be adapted for use in the drying of moist materials such as grain or the like. Irrespective, however, of the particular use to which the apparatus may be put, the essential features thereof are at all times preserved.

Heretofore, in the batch heating of foundry sand, the apparatus which has been employed has been of the tumbler type, including as it does a rotatable drum having open ends through which heated air is passed. The sand batch Within the drum is caused, upon rotation of the drum, to tumble in the manner of clothes in a tumbler-type of electric or gas heated clothes dryer. Such apparatus presents numerous problems from a mechanical and operational point of view, and furthermore, the efficiency of such apparatus is low due to the fact that heat penetration through large volumes of sand is slow. Among the mechanical and operational ditliculties which are encountered with a tumbler drum-type heating apparatus are those that are associated with charging of the cool sand into the drum and emptying the heated batch of sand from the drum when the desired temperature has been attained. If the drum is emptied through an end thereof, complicated drum tilting mechanism must be employed. If the drum is emptied through a drum gate, much residual sand is likely to be left within the drum. In either event, heating operations must be suspended during both charging and emptying operations, thus requiring burner adjustment or other attention as well as idle time losses. Localized overheating at the burner end of the drum and heat starvation at the end of the drum that is remote from the burner are problems that must be contended with. Additionally, the problem of providing suitable sand seals arises in connection with a tumbler drum-type heating apparatus.

The present invention is designed to overcome the above-noted limitations that are attendant upon the construction and use of a conventional tumbler drum-type sand heating apparatus, and accordingly, the invention contemplates the provision of a novel sand heating apparatus in which most of these problems are either minimized or eliminated altogether. Insofar as heat penetration is concerned, the invention makes provision for the creation of a continuous thin trajectory curtain of sand and for 3,144,244 Patented Aug. 11, 1964 the intersection of a gaseous flame through this curtain, thus establishing a primary heating zone where all of the sand particles or grains are subjected to intense heat in this region. From this primary heating region, the sand particles on the one hand and the products of combustion resulting from the flame on the other hand are caused to move to various secondary heating regions; where further intimate encounters take place while the sand is being maintained in a state of sparse agitation to the end that there is effected additional heating of the sand. Insofar as charging and batch emptying operations are concerned, the invention makes provision for a stationary housing for the sand instead of a rotatable drum and within the housing there is provided a series of sand agitating and conveying members which withdraw sand from the bottom regions of the housing interior and project the same into the aforementioned trajectory. The housing is provided with a sand inlet or charging opening at the top thereof, and a lower batch discharge gate. The sand agitating and conveying members are continuously movable, and since the housing is stationary, the successive batches may be introduced into the housing and removed through the discharge gate without necessitating cessation of the operation of the sand agitating and con veying members. When the discharge gate is opened after a batch of sand is heated to the proper extent, the moving sand agitating and conveying members assist in discharging the sand substantially to completion. The problems of effectively sealing the sand within the housing during operation on any given batch are greatly minimized according to the present invention by the provision of novel sand seals in the regions where the agitating shaft for the sand agitating and conveying members pass through the housing side wall, and associated with these sand seals are novel means for dissipating heat from the shaft in the vicinity of the shaft bearings so that there will be little danger of the bearings becoming overheated.

The present invention is possessed of advantageous novel structural features which are not applicable to a conventional tumbler drum-type sand heating apparatus and among the more important of these is a novel discharge gate construction which embodies an automatically operable sand deflector plate which, when the discharge gate proper is opened, automatically becomes projected into the trajectory of sand within the housing so that during such time as the gate remains open, all sand which is projected into the trajectory will be deflected and directed outwardly through the discharge gate opening, the deflecting operation continuing until substantially all of the sand in the housing is discharged from the housing.

Operational and constructional advantages such as ruggedness and durability, simplicity, smoothness and relative silence in operation, ease of assembly and dismantlement for purposes of inspection of parts, replacement or repair thereof, and reliablility of operation without constant supervision on the part of an operator, are further desirable features which have been borne in mind in the production and development of the present sand heating apparatus.

The provision of a sand heating apparatus of the aforementioned character being the principal object of the invention, numerous other objects and advantages, not at this time enumerated, will become readily apparent as the following detailed description ensues.

In the accompanying four sheets of drawings forming a part of this specification, one illustrative embodiment of the invention has been shown.

In these drawings:

FIG. 1 is a front perspective View of a. foundry sand heating apparatus constructed according to the principles of the present invention;

FIG. 2 is a sectional view taken substantially centrally and vertically through the housing of the apparatus;

FIG. 3 is a sectional view taken on the line 33 of FIG. 2;

FIG. 4 is a rear view of the apparatus with portions thereof in the vicinity of the discharge gate broken away and other portions removed in order more clearly to reveal the nature of the discharge gate;

FIG. 5 is an enlarged fragmentary sectional view taken substantially centrally and longitudinally through a gate assembly employed in connection with the present invention and showing the gate proper in its open position; and

FIG. 6 is a sectional view similar to FIG. 5, but showing the gate proper in its closed position.

Referring now to the drawings in detail, and in particular to FIG. 1, the heating apparatus that is illustrated therein and is designated in its entirety by the reference numeral 10 has been designed for use specifically in the batch heating of foundry sand preparatory to transferring the heated batch to a mulling machine for admixture with a suitable coating resin. Briefly, the apparatus involves in its general organization a heavy gauge sheet or plate metal housing structure 12 embodying a housing proper 14. The latter embodies a curved or arcuate bottom wall plate 16 (see FIG. 2) and defines an internal sand heating and circulating chamber 18. A batch of sand which is introduced into the chamber 18 is adapted to be operated upon by a rotary series of sand agitating and conveying members in the form of elongated bucket-like structures or scoops 20 (hereinafter referred to simply as scoops) which create within the chamber 18 a sand movement pattern which is conducive toward elfective heat exchange relation between a sand heating flame issuing from a burner 22 and the moving sand within the chamber.

The burner 22 is disposed adjacent to an olfset pocket 24 of the chamber 18 and the scoops 20 are so disposed in the peripheral regions of an open squirrel-cage rotor or structure 26 that, upon rotation of the structure at a predetermined speed, they exert a scooping action on the sand in the bottom region of the chamber 13 and cause the sand to be distributed in and around the chamber 18 in a particular manner so that primary heat assimilation by the sand in the vicinity of the offset pocket 24 of the chamber occurs. Secondary heat assimilation of the sand takes place in the central regions of the chamber 18. The primary and secondary heating of the sand in the chamber 18 constitutes one of the principal features of the present invention and it will be described in considerable detail presently. However, forthe present it is pointed out briefly that the sand scoops operate by a positive sand conveying action, first, to pick up sand quantities which are commensurate with their volumetric capacity, and then to convey successive quantities or amounts of sand to the primary heating region in front of the burner 22 where they are projected into a trajectory which intersects the burner flame. Each scoop emerges from the lower portion of the chamber 18 with an excess quantity of sand piled high over the open rim or mouth of the scoop and the speed of rotation of the squirrel-cage structure 26 is such that there is spillage throughout and over the entire upper circumferential region of the structure. This spilled sand falls downwardly through the open squirrel-cage structure in the form of a sparse suspension or rain of sand and secondary heating gases, resulting from the flame at the burner 22 in the primary heating region, pass through the sand suspension and impart further heat to the sand thereof. Sand from both the primary and secondary heating regions falls to the lower portion or the chamber 18 and the process of sand agitation and distribution is continuous throughout the entire heating cycle.

Ignition is maintained constantly at the burner 22 and the squirrel-cage structure 26 is continuously rotated without shutdown during batch changes. At the end of the heating cycle, a discharge gate 28 is opened. This gate is disposed above the level of the bottom wall 16 of the housing proper 14 and adjacent to the sand trajectory across the burner flame. At the time that the discharge gate 28 is opened, a deflector plate 34 is automatically projected through a discharge opening 32 and into the trajectory path so that, as sand continues to be flung into the trajectory by the scoops 20, the heated sand, instead of returning to the lower portion of the chamber 18, is discharged from the chamber into a suitable receptacle (not shown) for immediate transfer while still hot to a sand mulling apparatus (also not shown). When no further sand issues from the discharge opening 32, the gate is closed and a fresh charge or batch of unheated sand is introduced into the chamber 13 through a charging opening 34 in the upper portion of the housing proper 14.

Specifically, and as best seen in FIGS. 1, 2 and 4, the housing structure 12 involves in its general organization a pair of full- height side plates 40 and 42, a partial height back plate 44 (see FIG. 2), upper and lower front plates 46 and 48, an intermediate front plate 50, and the previously-mentioned curved bottom wall plate 16. The upper edge of the intermediate front plate 50 is connected to the lower edge of the upper front plate 46 by a horizontally disposed shelf plate 52. A top plate 54 extends across the housing structure, and in combination with the side plates 40 and 42, the back plate 44, the front plates 46 and 50, and the bottom plate 16, defines the internal sand heating and circulating chamber 18. A charging stack 5% at the top of the housing structure 12 defines the charging opening 34 and communicates with the upper portion of the chamber 18 through an inclined perforated air distribution plate 60. An exhaust opening 62 is provided in the side plate 40 above the level of the plate 60 and is adapted to be connected to the suction side of a blower, and exhaust stack or other exhaust means (not shown) for the air and other gases leaving the heating chamber 18. A screen 62 for catching oversized material or scrap extends across the upper portion of the heating chamber 18 beneath the air distribution plate and slopes downwardly and outwardly in opposite directions from a transverse center line. The side wall 40 is provided with a peephole assembly 66 in order that the interior of the housing structure may be viewed from the outside.

Referring now to FIGS. 2 and 3, the previously-mentioned squirrel-cage structure 26 includes a horizontally disposed supporting shaft 70, the ends of which are .rotatably journalled in shielded bearing assemblies 72 on the side plates 40 and 42. Means are provided for inhibiting the flow of heat by conduction from the shaft 70 to the bearing assemblies 72, and accordingly, each bearing assembly is bolted as at 74 to a vertically extending supporting plate 76 which is maintained spaced from the adjacent side plate 40 or 42, as the case may be, by a rectangular cage structure 78, which, in combination with the side plate 4! defines a chamber 79. A sand return opening 80 is provided in the side plate near the bottom of the chamber 79. A combined sand shield and sand flinger plate 82 is disposed within the space between each supporting plate 76 and the adjacent side plate of the housing structure and is secured in position by a set screw 84. Recessed bushings 86 support the ends of the shaft 70 within the inner faces of the bearing assemblies 72. The extremities of the shaft 70 pass through clearance openings 88 in the adjacent side plates and also through second clearance openings 90 in the supporting plates. 76. 7

From the above description, it will be seen that heat of conduction is inhibited from flowing to the bearing assemblies 72 from the shaft 70 by reason of the recessed bushings 86 as well as by reason of the flinger plates 82 which function to a certain extent as heat radiatiors behind the supporting plates 76. Heat of convection and of radiation from the housing structure walls is shielded from the bearing assemblies by reason of the cage structures 78, the flinger plates 82 and the supporting plates 76, all of which are interposed in a heat radiating area.

The bearing assemblies 72 are shielded from contact with any sand which may escape from the chamber 18 through the clearance opening 88 by reason of the flinger plates 82 which have a tendency to throw such sand radially outwardly of the shaft 70 where it will return to the chamber 18 through the openings 80.

In order further to dissipate heat of conduction from the shaft '70, heat-radiating hub-like extensions 92 are provided on the recessed bushings 86 and are formed with radial heat-radiating fins 94.

The shaft is adapted to be driven in one direction by an electric motor (not shown), operating through a suitable power train (also not shown), the terminal application of power being applied to a sheave 96 which is keyed as at 98 to one end of the shaft 70 exteriorly of the housing structure 12.

The squirrel-cage structure 26 within the chamber 18 is centered on the shaft 70 between the two side plates 40 and 42 and involves in its general organization a pair of vertically extending spaced apart end plates 100 and 102 (see FIGS. 2 and 3) which are bolted as at 104 to respective hubs 106. The latter are keyed as at 108 to the shaft 70. Set screws 110 hold the bolts 104 in place. The end plates 180 and 102 are circular and the previously-mentioned scoops are in the form of elongated trough-like receptacles presenting open rectangular rims 112, sloping side walls 114, curved bottoms 116, and flat end walls 118. One side wall 114 of each scoop 20 is welded to the outer periphery of each end plate 100 and 102 and the various scoops are equally and circumferentially spaced about the periphery of the squirrel-cage structure 26 as best shown in FIG. 2, and as a result, their open rims 112 face in the leading direction of rotation of the structure. The scoops 20, in addition to serving their sand conveying and impelling function, also serve to rigidify the squirrel-cage structure in the manner of peripheral spacers which extend between the two end plates 100 and 1132. Additional spacing members 121) extend between the two end plates 100 and 102 (see FIG. 2).

Referring now particularly to FIG. 2, the curved bottom wall plate 16 of the housing proper 14 is concentric with the horizontal axis of the shaft 70 throughout a major portion of its extent and its radius of curvature is such that only a very small clearance exists between the curved portion of the plate and the various scoops 20 as they sweep past the bottom wall plate during rotation of the squirrel-cage structure 26 in a counterclockwise direction as viewed in FIG. 2. The forward region of the bottom plate 16 is provided with a tangential planar section 122 which lies in an inclined plane that is slightly offset from the inclined plane of a similar planar section 124 provided in the lower region of the intermediate front plate 50 of the housing structure. Pairs of angle pieces 126 are secured by screws 127 to the side plates 40 and 42 and establish therebetween opposed guideways 128 (FIGS. 2, 5 and 6), which slidably receive the side edges of a flat gate plate 130, such gate plate forming a part of the previously-mentioned discharge gate 28. The upper edge of the inclined planar section 122 of the bottom wall plate 16 and the loweredge of the inclined planar section 124 of the intermediate front plate 50, define therebetween the previously-mentioned discharge opening 32 through which heated sand is adapted to be discharged from the chamber 18 during each batch emptying operation. The specific nature of the discharge gate 28 and the manner in which sand is discharged fromthe heating chamber 18 will be set forth in detail presently.

Still referring to FIG. 2, an open-ended sand collecting or gathering funnel 140 of wide U-shape design is secured to the inside surface of the intermediate front plate 50 within the chamber 18 and presents a wide upper rim 142 and a narrow lower rim 144. The upper rim 142 of the funnel 140 presents a sand receiving opening which is positioned directly in the trajectory of sand issuing from the various scoops 28 as they sweep forwardly and downwardly in their circular path of movement within the sand heating chamber 18. The lower rim 144 of the funnel defines a restricted discharge opening which is directed downwardly on an incline immediately above the inclined planar section 122 of the bottom wall plate 16 of the housing structure 12. The manner of operation of the sand collecting or gathering funnel 141) will be described in greater detail when the operation of the apparatus as a whole is set forth. A heat shield 146 extends on an incline downwards and rearwards from the juncture between the screen 64 and the upper front plate 46 to a point close to the circular path of movement of the scoops 21B and its function likewise will be made clear subsequently.

Inasmuch as the functioning of the discharge gate 28 is largely dependent upon the specific movement of sand within the chamber 18 under the impelling influence of the various scoops 20, the nature of this discharge gate will be set forth after the operation of the sand heating phase of the apparatus has been made clear.

The manner in which successive batches of sand are heated within the heating chamber 18 is apparent from and may conveniently be described with reference to FIG. 2. Heat is supplied to the interior of the heating chamber 18 by means of the previously-mentioned burner 22 which is preferably in the form of a conventional line burner. This burner is mounted on the horizontal shelf plate 52 and has its downwardly facing burner plate 151) in register with an elongated burner opening 151 in the shelf plate. A series of jet-producing openings 152 in the burner plate 15h produces, in effect, an elongated flame when the burner is ignited, and this flame is directed downwardly through the opening 151 and traverses the trajectory of sand issuing from the various moving scoops 20 and flowing 'to the funnel 140. The exhaust opening 62 in the side plate 40 of the housing structure 12 is adapted to be operatively connected to the suction side of a blower or similar exhaust means as previously pointed out and, as a consequence, the flame issuing from the burner 22 is drawn laterally so that it traverses the sand trajectory over a wide region.

The specific combustion system which is associated with the burner 22 forms no part of the present. invention and various systems are available for use for supplying combustible gaseous constituents to the burner. Preferably, these gaseous constituents are fuel gas and air, these gases being suitably combined in a proportional mixing device (not shown) at a predetermined fuel-air ratio before being conducted to the burner for combustion purposes. Obviously, if desired, a mixing type burner may be employed in place of the line burner 22.

During charging of the housing proper 14 through the charging stack 58, oversized screenings are caught by the screen 64, but the main body of the batch of sand falls to the lower regions of the rotating squirrel-cage structure 26. Although the quantity of sand in a batch may be as much as would fill one-third of the total volume of the heating chamber 18, the sand is kept substantially entirely in agitated suspension within the chamber due to the scooping, spilling and flinging action of the various scoops 20 on the sand. The scooping action takes place in the bottom portion of the heating chamber 18 where the scoops 211 traverse the curved portion of the bottom wall plate 16, lift the sand bodily upwardly along the rear region of said plate, and assume substantially up right positions as they approach and leave the lower edge region of the partial back plate 44. As the scoops 2t) commence their movement over the upper peripheral region of the rotating squirrel-cage structure 26,.they are filled to overflowing with sand and as their direction of orientation becomes progressively more inclined during passage across the upper regions of the squirrel-cage srtucture, they commence to spill sand downwardly through the open cage-like structure. At first, this sand spillage is the result of overfilling of the scoops and a drainage of the heap or mound of sand which represents the overfill. Subsequently, however, the spillage is the result of tilting of the scoops and an actual pouring of some of the sand from the scoops takes place. Finally, as the scoops approach the offset pocket 24 existing by reason of the horizontal shelf plate 52, there is a forward flinging of the sand under the influence of centrifugal forces acting on the sand so that the aforementioned trajectory or curtain of sand is established for entry into the funnel 140. The rate of rotation of the squirrel-cage structure 26 is carefully regulated so that these phenomena will obtain. The size of the discharge opening afforded by the lower rim 144 of the funnel 140 is selected as a function of the speed of rotation of the squirrel-cage structure 26 so that the funnel restricts the flow of sand back to the bottom regions of the heating chamber 18. Either too large an opening or too slow a rate of rotation of the squirrel-cage will admit the sand too freely to the bottom regions of the chamber so that there will be a pile-up of sand tending to overload the shaft 70 and the driving motor therefor. Too small a funnel opening or too rapid a rate of rotation of the squirrel-cage structure will unduly restrict the flow of sand to the bottom regions of the chamber so that the scoops 20 will have insufficient sand at hand for com plete filling thereof, and after the scoops have spilled their contents at the upper regions of the squirrel-cage structure as heretofore described, there will be insufficient sand to establish a substantial trajectory in the vicinity of the burner 22. One of the principal functions of the funnel 140 is to prevent free flow of sand from the sand trajectory into the entry region between the squirrel-cage structure and the inclined planar section 122 of the bottom wall plate 16. If sand is allowed to accumulate in this region too freely, binding of the scoops will result.

With the proper speed of rotation of the squirrel-cage structure 26, there is established an ideal trajectory of sand passing through the elongated flame isuing from the burner 22 and the sand in this curtain-like trajectory is subjected to an intense heating effect in what may be considered to be a primary heating zone. In the regions of the heating chamber 18 more remote from the burner 22 and the offset portion or pocket 24, there is considerable turbulence of the partially burned products of combustion which then become intermixed for more complete combustion. The medial region of the heating chamber 18 becomes, in effect, a combustion chamber and establishes a secondary heating zone where the sand which spills from the scoops 20 passing across the upper region of the squirrel-cage structure 26 and falls through the central portion of the squirrel-cage structure is subjected on a secondary or further heating action.

The perforated air distribution plate 60 serves to prevent short circuiting of the gaseous products of combustion directly to the exhaust opening 62 with a consequent loss of both heat and sand. This distribution plate retards the upward flow of the gases and contributes toward an even distribution of heat throughout the chamber 18, while at the same time, keeping the sand in the vicinity of the squirrel-cage structure 26 by preventing the sand from becoming unduly airborne.

Experiencewill dictate the length of the heating cycle for any given particle size or grade of sand in a batch. Ordinarily, with an apparatus having a capacity of 250 pounds per batch, a heating cycle of two and one-half minutes will suflice to raise the sand to the required temperature. However, if desired, a thermometer 153 may be mounted on the back plate 44 in order that it will give an indication or may be caused to render a signal when the sand has reached the desired temperature. At such time, gate opening operations will be carried out and the heated batch of sand will be delivered through the discharge openings 32 to the aforementioned receptacle which may conveniently be positioned in front of the housing structure 12 between a pair of generally triangular extensions 154 on the front lower corners of the side plates 40 and 42.

Referring now to FIGS. 2, 4, 5 and 6, the previouslymentioned discharge gate 28, including the flat gate plate and the sand deflector plate 30, is adapted to be operated under the control of an air cylinder 200. The latter is suitably supported on a bracket 202 which is mounted on the lower front plate 48 of the housing structure 12. The air cylinder 200 is provided with a plunger 204, the forward end of which carries a head 206. The latter is secured to an angle piece 208, the right angle flanges 210 and 212 of which are secured along their edges to the outer side of the gate plate 130. The sand deflector plate 30 is provided with side wings 214 which are pivotally connected by horizontal pivot pins 216 to the side plates 40 and 42 of the housing structure 12.

The deflector plate 30 is normally urged under the influence of two coil springs 218 to an advanced position wherein it is shown in dotted lines in FIG. 4 and wherein it is projected beneath the discharge opening of the funnel 140. As shown in FIG. 4, the springs surround the pivot pins 216 and have their ends suitably anchored to the side wings 214 and one of the walls 40 or 42, as the case may be. When the gate plate 130 is disposed across the discharge opening 32, the sand deflector plate 30 is maintained in the retracted position wherein it is shown in full lines in FIGS. 4 and 6. Accordingly, the width of the gate plate 130 in a direction transversely of the housing structure 12 is greater than the distance between the side wings 214 of the deflector plate 30 so that the lower edge of the gate plate will engage the upper edges of these side wings during gate closing movements and exert a camming action on the sand deflector plate 30 as a whole, thus tending to withdraw the plate from the interior of the heating chamber 26. The width of the angle piece 208 in the transverse direction of the housing structure is less than the distance between the side wings 214 so that this angle piece may move between these side wings during the terminal gate closing movements as shown in FIG. 6 and exert a camming effect on the upper edge of the deflector plate 30 so as to hold the latter in the retracted position wherein it is shown in full lines.

From the above description, it will be seen that pro jection of the deflector plate 30 into the heating chamber 18 is automatically effected each time the gate structure is moved to its open position, and that it is withdrawn from the chamber each time the gate structure is moved to its closed position. In its projected position, its withdrawal being effected by the camming engagement of the leading edge of the gate plate 128 with the upper edges of the side wings 214, the deflector plate 30 underlies the lower rim 144 of the funnel so that the sand issuing from the funnel is deflected out through the discharge opening 32. As previously stated, the squirrel-cage structure 26 is continuously rotatable and continues to rotate during batch emptying operations. During such time as the gate structure is in its open condition, the establishing of a trajectory of sand across the front of the burner 22 and the deposition of this sand into the funnel 140 is relied upon for batch emptying purposes.

It is to be noted that the sand discharge opening 32 is effectively in register with the sand trajectory and is disposed at the terminal end of such trajectory. There fore, in the absence of the funnel 140, sand issuing from the trajectory ordinarily would be directed by the deflector plate 30 outwardly from the chamber 18 through the discharge opening 32. The function of the deflector plate 30 is essentially to insure that all of the sand issuing from the trajectory will be discharged from the chamber during emptying operations. However, it is within the purview of the present invention to dispense with either the funnel 140 or the deflector plate 30, or to dispense 9 with both of these instrumentalities, and to allow sand to be ejected from the trajectory directly through the discharge opening 32.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without de parting from the spirit or scope of the invention. For example, while in the illustrated form of the invention, the apparatus is of a semi-automatic type in that batch charging and discharging operations are initiated under the control of an operator, fully automatic operations are contemplated wherein the gate opening and closing movements may be initiated under the control of a thermostat (not shown) which may be substituted for the thermometer 153 and may control the operation of the air cylinder 200. Therefore, only insofar as the invention has particularly been pointed out in the accompanying claims is it to be limited.

Having thus described the invention what I claim as new and desire to secure by Letters Patent is:

1. An apparatus adapted to heat foundry sand or the like and comprising a housing defining an internal sand circulating and heating chamber and having an upstanding front wall therein, there being a filling opening in the upper regions of said housing defining a sand inlet for the chamber, a rotor mounted for rotation about a horizontal axis within the chamber and spaced rearwardly from said front Wall, a series of scoops fixedly disposed in circumferentially spaced relationship on the periphery of said rotor, said scoops being operable upon rotation of the rotor in one direction at a predetermined speed of rotation to elevate sand at the rear side of the rotor, carry the same forwardly over the upper region of the rotor, and discharge the same in an approximate tangential trajectory passing generally downwardly through the intervening space existing between-said front wall and the rotor, said front wall being provided with a burner opening in register with said intervening space, a burner positioned to deliver a flame through said burner opening in heat exchange relation with the sand in said trajectory, means for rotating said rotor at said predetermined speed and in said one direction, said front wall being provided with a sand-discharge opening therein below the level of said burner opening and in register with said intervening space and for discharging sand issuing from the terminal end of the trajectory, and a gate movable between open and closed positions with respect to said sand-discharge opening.

2. An apparatus as set forth in claim 1 and including,

additionally, an open-ended receptacle disposed in said intervening space for receiving sand from the terminal region of said trajectory, said receptacle being provided with a restricted opening in the lower regions thereof for retarding the flow of sand downwardly through said intervening space. 3. An apparatus as set forth in claim 2 and wherein the restricted opening in the receptacle is in register with said discharge opening for the discharge of sand through the latter when said gate is inits open position.

4. An apparatus as set forth in claim 3 and including, additionally, a heat shield interposed between said front wall and the upper region of the rotor for preventing short circuiting of heat-generated by said flame upwardly between the rotor and said front wall.

5. An apparatus adapted to heat foundry sand or the like and comprising a housing defining an internal sand circulating and heating chamber and having an upstanding front wall therein, there being a filling opening in the upper regions of said housing defining a sand inlet for the chamber, a rotor mounted for rotation about a horizontal axis within the chamber and spaced rearwardly from said front wall, a series of scoops fixedly disposed in circumferentially spaced relationship on the periphery of said rotor, said scoops being operable upon rotation of the rotor in one'direction at a predetermined speed of rotation to elevate sand at the rear side of the rotor, carry the same forwardly over the upper region of the rotor, and discharge the same in an approximately tangential trajectory passing generally downwardly through the intervening space existing between said front wall and the rotor,,said front wall being provided with a burner opening in register with said intervening space, a burner positioned to deliver a flame through said burner opening in heat exhange relation with the sand in said trajectory, means for rotating said rotor at said predetermined speed and in said one direction, said front wall being provided with a sand-discharge opening therein below the level of said burner opening in register with said intervening space for receiving sand from the terminal end of the trajectory, a gate movable between open and closed positions with respect to said sand-discharge opening, and a deflector plate mounted on said housing for movement between a retracted inoperative position wherein it is disposed exteriorly of the chamber and an advanced operative position wherein it is projected partially through said sand-discharge opening for deflecting sand from the trajectory through the sand-discharge opening when the gate is in its open position.

6. An apparatus as set forth in claim 5 and wherein the deflector plate is pivoted to the housing exteriorly of the chamber for swinging movements about a horizontal axis.

7. An apparatus adapted to heat foundry sand or the like and comprising a housing defining an internal sand circulating and heating chamber and having an upstanding front Wall therein, there being a filling opening in the' upper regions of said housing defining a sand inlet for the chamber, a rotor mounted for rotation about a horizontal axis within the chamber and spaced rearwardly from said front wall, a series of scoops fixedly disposed in circumferentially spaced relationship on the periphery of said rotor, said scoops being operable upon rotation of the rotor in one direction at a predetermined speed of rotation to elevate sand at the rear side of the rotor, carry the same forwardly over the upper region of the rotor, and discharge the same in a trajectory passing generally downwardly through the intervening space existing between said front wall and the rotor, said front wall being provided with a burner opening in register with said intervening space, a burner positioned to deliver a flame through said burner opening in heat exchange relation with the sand in said trajectory, meansfor rotating said rotor at said predetermined speed and in said one direction, said front wall being provided with a sanddischarge opening therein below the level of said burner opening in register with said intervening space and for discharging sand issuing from the terminal end of the trajectory, a gate movable between open and closed positions with respect to said sand-discharge opening, a deflector plate mounted on said housing for movement between a retracted inoperative position wherein it is disposed exteriorly of the chamber and an advanced position wherein it is projected partially through said sand-discharge opening and into said trajectory for deflecting sand from the trajectory through the sand-discharge opening when the gate is in its open position, means normally urging said deflector plate toward its advanced position, and means automatically operable upon movement of the gate toward its closed position for effecting retraction of the deflector plate from its advanced position to its retracted position against the action of said spring means.

8. An apparatus as set forth in claim 7 and wherein the retracting means for said deflector plate includes cooperating cam surfaces on the gate and deflector plate respectively.

9., An apparatus adapted to heat foundry sand or the like and comprising a housing defining an internal sand circulating and heating chamber and havingan upstanding front wall therein, there being a filling opening in the upper regions of said housing defining a sand inlet for the chamber, an open cage-like rotor mounted for rotation about a horizontal axis within the chamber and spaced rearwardly from said front wall, said rotor including a series of elongated trough-like scoops fixedly mounted on the periphery of the rotor in circumferentially spaced relationship with their axes parallel to the axis of rotation of the rotor and with their open rims presented forwardly in the direction of rotation of the rotor, said scoops being operable upon rotation of the rotor in said direction at a predetermined speed of rotation to elevate individual masses of sand during their rising movements at the rear side of the rotor, to spill portions of said masses of sand as they become inclined during their forward movement in the upper regions of the rotor so that such spilled sand falls by gravity downwardly through the open cage-like rotor, and to fling such sand as remains captive within the scoops forwardly as the scoops commence to descend at the forward side of the rotor and thus establish a forwardly and downwardly inclined sand trajectory in the forward regions of the chamber in the intervening space between the front wall and the rotor, said front wall being provided with a burner opening in register with said intervening space, and a burner positioned to deliver a flame through said burner opening in heat exchange relationship with the sand of said trajectory and thus establish a primary heating zone between the rotor and front wall of the housing, the products of combustion resulting from said flame being directed generally radially inwardly of the rotor to thus establish a secondary heating zone in and around the rotor.

10. An apparatus as set forth in claim 9 and including, additionally, a heat shield above the level of said burner and extending between said front wall and the peripheral region of the rotor for preventing upward short-circuiting of heat around the forward region of the rotor.

11. An apparatus as set forth in claim 9 and wherein said chamber is provided with a bottom wall having a curved region which is concentric with the axis of rotation of the rotor, the radius ofcurvature of said curved region being slightly greater than the over-all radius of the rotor.

12. An apparatus adapted to heat foundry sand or the like and comprising a housing defining an internal sand circulating and heating chamber and having an upstanding front wall therein, there being a filling opening in the upper regions of said housing defining a sand inlet for the chamber, an open cage-like rotor mounted for rotation about a horizontal axis within the chamber and spaced rearwardly from said front wall, said rotor including a series of elongated trough-like scoops mounted on the periphery of the rotor in circumferentially spaced relationship with their axes parallel to the axis of rotation of the rotor and with their open rims presented forwardly in the direction of rotation of the rotor, said scoops being operable upon rotation of the rotor in said direction at a predetermined speed of rotation to elevate individual masses of sand during their rising movements at the rear side of the rotor, to spill portions of said masses of sand as they become inclined during their forward movement in the upper regions of the rotor so that such spilled sand falls by gravity downwardly through the open cage-like rotor, and to fling such sand as remains captive within the scoops forwardly as the scoops commence to descend at the forward side of the rotor and thus establish a forwardly and downwardly inclined sand trajectory in the forward regions of the chamber in the intervening space between the front wall and the rotor, said front wall being provided with a burner opening in register with said intervening space, a burner positioned to deliver a flame through said burner opening in heat exchange relationship with the sand of said trajectory and thus establish a primary heating zone between the rotor and front Wall of the housing, the products of combustion resultingfrom said flame being directed generally radially inwardly of the rotor to thus establish a secondary heating zone in and around the rotor, said front wall being provided with a sand discharge opening therein below the level of said burner and in register with the terminal end of the sand trajectory, and a gate movable between open and closed positions with respect to said sand discharge opening.

13. An apparatus as set forth in claim 12 and including, additionally, an open-ended receptacle having a restricted bottom opening and disposed in the terminal region of said trajectory for receiving sand therein and retarding the flow thereof downwardly in the chamber and for collecting sand and directing the same toward said sand discharge opening.

14. An apparatus adapted to heat foundry sand or the like and comprising a housing defining an internal sand circulating and heating chamber and having an upstanding front wall therein, there being a filling opening in the upper regions of said housing defining a sand inlet for the chamber, an open cage-like rotor mounted for rotation about a horizontal axis within the chamber and spaced inwardly from said front wall, said rotor including a series of elongated trough-like scoops fixedly mounted on the periphery of the rotor in circumferentially spaced relationship with their axes parallel to the axis of rotation of the rotor and with their open rims presented forwardly in the direction of rotation of the rotor, said scoops being operable upon rotation of the rotor in said direction at a predetermined speed of rotation to elevate individual masses of sand during their rising movements at the rear side of the rotor, to spill portions of said masses of sand as they become inclined during their forward movement in the upper regions of the rotor so that such spilled sand falls by gravity downwardly through the open cage-like rotor, and to fling such sand as remains captive within the scoops forwardly as the scoops commence to descend at the forward side of the rotor and thus establish a forwardly and downwardly inclined sand trajectory in the forward regions of the chamber in the intervening space between the front wall and the rotor, a burner positioned to deliver a flame through said burner opening in heat exchange relationship with the sand of said trajectory and thus establish a primary heating zone between the rotor and front wall of the housing, the products of combustion resulting from said flame being directed generally radially inwardly of the rotor to thus establish a secondary heating zone in and around the rotor, said front wall being provided with a sand-discharge opening therein below the level of said burner, a gate movable between open and closed positions with respect to said sand-discharge opening, a funnel-like receptacle disposed in the terminal region of said trajectory for receiving sand therein and directing the same generally toward said gate opening, and a deflector platelmounted on said housing for movement between a retracted inoperative position wherein it is disposed wholly exteriorly of the chamber and an advanced operative position wherein it is projected partially through said sand-discharge opening and into said trajectory for deflecting sand from the trajectory through the sand discharge-opening when the gate is in its open position.

15. An apparatus as set forth in claim 14 and including, additionally, spring means normally urging said deflector plate toward its advanced operative position, and means automatically operable upon movement of the gate toward its closed inoperative position for effecting retraction of the deflector plate against the yielding action of said spring means. I

16. An apparatus as set forth in claim 14 and wherein the deflector plate is pivoted to the housing exteriorly of the chamber for swinging movements about a horizontal axls.

17. An apparatus as set forth in claim 14 and wherein References Cited in the file of this patent the deflector plate is pivoted to the housing exteriorly UNITED STATES PATENTS of the chamber for swinging movements about a horizontal axis, and the means for retracting the d fl t 305,596 pm ng r Sept. 23, 1884 plate comprises cooperating cam surfaces on h gate 5 1,937,479 H6111 Sept. 3, 1912 and deflector plate. 1,307,054 Wadman May 26, 1931

Claims (1)

1. AN APPARATUS ADAPTED TO HEAT FOUNDRY SAND OR THE LIKE AND COMPRISING A HOUSING DEFINING AN INTERNAL SAND CIRCULATING AND HEATING CHAMBER AND HAVING AN UPSTANDING FRONT WALL THEREIN, THERE BEING A FILLING OPENING IN THE UPPER REGIONS OF SAID HOUSING DEFINING A SAND INLET FOR THE CHAMBER, A ROTOR MOUNTED FOR ROTATION ABOUT A HORIZONTAL AXIS WITHIN THE CHAMBER AND SPACED REARWARDLY FROM SAID FRONT WALL, A SERIES OF SCOOPS FIXEDLY DISPOSED IN CIRCUMFERENTIALLY SPACED RELATIONSHIP ON THE PERIPHERY OF SAID ROTOR, SAID SCOOPS BEING OPERABLE UPON ROTATION OF THE ROTOR IN ONE DIRECTION AT A PREDETERMINED SPEED OF ROTATION TO ELEVATE SAND AT THE REAR SIDE OF THE ROTOR, CARRY THE SAME FORWARDLY OVER THE UPPER REGION OF THE ROTOR, AND DISCHARGE THE SAME IN AN APPROXIMATE TANGENTIAL TRAJECTORY PASSING GENERALLY DOWNWARDLY THROUGH THE INTERVENING SPACE EXISTING BETWEEN SAID FRONT WALL AND THE ROTOR, SAID FRONT WALL BEING PROVIDED WITH A BURNER OPENING IN REGISTER WITH SAID INTERVENING SPACE, A BURNER POSITIONED TO DELIVER A FLAME THROUGH SAID BURNER OPENING IN

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