MXPA97010514A - System of two stages by heat for the treatment, removal and regeneration of the ar - Google Patents

Abstract

In order to efficiently treat and demold a non-ferrous metal function by heat, and then fully regenerate the reject male sand, a two-stage system is provided for processing non-ferrous metal castings and sand for males formed of sand and binder. The two-stage system includes a first step to remove the sand from the non-ferrous metal foundry while at the same time heat treating the non-ferrous metal foundry, and also includes a separate second stage to regenerate the sand for males . For this purpose, the fluidized and heated sand is used while the foundries and sand are transported together in the first stage and the sand alone is transported in the second stage for the recirculation of at least a portion of the sand at the first stage.

Description

SYSTEM OF TWO HEAT STAGES FOR TREATMENT. DISMOLLATION AND REGENERATION OF THE SAND Related Request This is a partial continuation of the joint pending application, filed previously, with serial number 08 / 844,738, filed on April 21, 1997, which is a partial continuation of the joint pending application, filed previously, with the number of Series 08 / 770,343, filed on December 20, 1996.

FIELD OF THE INVENTION The present invention relates generally to the foundry industry and, more particularly, to a vibratory sand regeneration system for regenerating foundry sand.

BACKGROUND OF THE INVENTION As is well known in the art, vibratory processing equipment has been developed to satisfy a wide range of diverse applications. It is often the case that a system for handling any of a variety of different materials will include as an integral component a vibratory conveyor. Generally, vibratory conveyors can be used to transport materials to and through a processing section to a post-processing location. In a particular application, a vibratory conveyor can find advantageous use in a foundry to transport metal castings or the like from one point to another after they have been formed. There is another very important need to be able to remove molds of sand and sand cores and to regenerate after that and recirculate the sand of casting which is typically glued by a resin to form the sand molds and to make the sand cores used in the molds to create interior voids during the conventional production of metal castings. After the metal castings have been formed, the sand molds and sand cores must be removed, after which the sand must be regenerated which has typically been carried out using a machine called a shaker. In connection with this, the shaker is typically of a vibratory nature and operates so that the moisture and sand of the bonded clay type is simply released to shakes of the metal castings. Optionally, sand molds and sand cores using resin-bonded type sand can be subjected to hot air in order to cause the resin glue in the sand to decompose so that the sand falls out of the castings of metal and the filling passages. In any case, the sand will typically be collected at the bottom of a chamber for subsequent heating or chemical processing to remove any remaining resin to thereby regenerate the sand which is stored for later reuse. As shown by Na anishi, in US Pat. No. 4,411,709, it has been known that resin-bonded sand molds and sand cores can be removed, and that the sand is simultaneously conditioned for reuse, heating the molding sand glued with resin and the sand for males at a sufficient temperature to be able to pyrolize the resin glues in the sand. As explained in Crafton, U.S. Patent Number: 5,354,038, and then in Bonnemasou et al., U.S. Patent Number: 5,423,370, it may be advantageous for this heating to be carried out using a fluidized bed of sand particles. In particular, Bonnemasou et al., US Pat. No. 5,423,370, states that fluidized beds are useful for removing sand cores from molten aluminum parts, but also warns that, when hot, these aluminum parts cast are such that they can not tolerate "even the most modest handling".

Moreover, although it is known to use heat to regenerate the sand by pyrolyzing the resin or binder bonding material, this has a dilemma that seems unsolvable; namely, how to apply sufficient heat to efficiently pyrolize the binder material in a manner that achieves significant energy conservation. There is also a related problem because metal castings must typically be treated at a specific temperature that must be controlled within strict tolerance in order to avoid damage to the castings and at the same time a highly heat treatment environment is provided efficient and effective Although the temperature for the heat treatment of the metal castings may be sufficient for demolding purposes, that is, for removing the cores that are formed of sand and the resin or binder glue material in the castings to regenerate the sand, that same temperature may not be enough to regenerate the sand by pyrolizing the glue material of resin or binder. Particularly for aluminum castings, the competition requirements are important for (1) efficiently and effectively heat treating the castings in an environment where the temperature is controlled within strict tolerance, (2) demolding the castings by removing the sand for cores thereof, and (3) regenerating the cored sand for reuse in a manner that fully ensures that the resin or binder glue material is completely pyrolyzed, or can be better achieved in more than one stage. The present invention relates to overcoming one or more of the above problems at the same time as achieving one or more of the resulting objects by providing an exclusive system of vibratory heat treatment, demoulding and sand regeneration.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and system for removing sand stuck with resin in the form of a sand mold and / or sand core of a piece of metal casting in order to regenerate the sand for later use. It is also an object of the invention to provide an apparatus and system having a fluidized bed through which hot castings are heat treated while being moved by vibratory forces to thereby remove the sand from the castings by the action combined vibratory forces, heated and fluidized sand, and the movement of the castings through the sand. It is another object of the present invention to provide the fluidized vibrating bed for transporting castings as an intermediate section of a vibratory conveyor fed with reclaimed hot sand and recirculated in a continuous conveying system. It is still a further object of the present invention to provide a two-stage system for processing metal and sand castings for cores formed of sand and resin or binder glue material that includes a second, completely separate, step to completely regenerate the sand for males removed from metal castings for reuse. In accordance with the above, the present invention is directed to an apparatus and system for removing and regenerating sand from the molds of the metal castings. The apparatus and system includes a fluidized bed together with means for vibrating the bed to move the castings from an inlet for the castings to receive the castings to an outlet for the castings to remove the castings . Means are provided for supplying hot sand to the fluidized bed at a point generally near the entrance to the casting and also means are provided for removing the reclaimed hot sand from the fluidized bed to be recirculated from a point generally close to the outlet of the castings. The apparatus and system also include means for recirculating hot sand from the sand removal means for the media supplying the sand where it is fluidized again. In addition, the apparatus and system includes means for deflecting excess sand therefrom, preferably in the form of an overflow conduit having a lower edge defining a spout at a preselected level. In an exemplary embodiment, the system comprises a heated chamber for removing and regenerating sand, a plenum for providing hot air to the hot chamber, and a support surface of the casting piece resembling a grate separating the hot chamber from the plenum. . The system also advantageously contemplates the support surface of the casting formed to have a plurality of dividers forming a plurality of conveyors for transporting castings extending longitudinally through the system. Preferably, a continuous uninterrupted vibrating casting support surface defines a continuous conveying path that leads from a casting load conveyor, to and through the fluidized bed, and then to a casting outlet conveyor. As a perhaps superior alternative for using dividers to form multiple rails for transporting castings, a pallet may be used in conjunction with a mechanical robot loading device to support a plurality of sand molds each containing a cast iron casting part. metal The vanes for the castings advantageously have a plurality of support bins for castings. Preferably, the support bins of the castings of each of the blades allow the hot air from the plenum to pass into the fluidization section where the sand in the fluidized bed is fluidized and heated. In a very preferred mode, the sand supply means comprises a sand distribution conveyor having a sand distribution opening disposed above the loading conveyor of castings upstream of the entry of the castings into the fluidized bed. The sand removal means also advantageously comprises a sand transfer conveyor communicating with a sand removal conduit which is preferably disposed generally at a point below the outlet conveyor of the castings at a point downstream of the sand. exit of the castings towards the fluidized bed. Still further, the sand recirculation means preferably comprises a sand return conveyor extending from the sand distribution conveyor to the sand transfer conveyor to recirculate the sand to be fluidized and heated in the fluidized bed. In a much more preferred embodiment, the apparatus and system includes an inlet seal for articulated castings from above the inlet of the fluidized bed and also includes an outlet seal for articulated castings from above the bed outlet. fluidized where the seals serve to conserve energy by retaining the heat within the fluidized bed. Additionally, the sand distribution conveyor, the sand transfer conveyor, and the sand return conveyor are all more advantageously portions of a continuous enclosed and insulated continuous vibratory transport system for recirculating hot sand through the fluidized bed. with very improved and efficient heat transfer characteristics. In the alternative embodiment, a plurality of hot gas distribution ducts and hot gas permeable vanes supporting the sand molds containing the metal castings are provided whereby the vanes are transported through the fluidized bed while they support on at least one pair of rails carried by and connected to the upper surfaces of the hot gas distribution ducts. In the alternative embodiment, each of the hot gas distribution ducts preferably entirely covers the width of the fluidized bed and has lower surfaces pierced in spaced relationship with a lower surface of the heating chamber. This allows the hot gas to be directed into the sand surrounding the distribution ducts. The hot gas will first be directed downwards, will immediately penetrate upwards through the sand between the hot gas distribution ducts and through the vanes causing all the loose sand to fluidize. In another alternative embodiment, a two-stage system for processing castings of metal and sand for cores formed of sand and binder is described. The two-stage system of this alternative embodiment includes a first stage for removing the core sand from the metal castings, while also heat treating the metal castings. Additionally, the two stage system includes a second, separate stage, to regenerate after that at least the core sand removed from the metal castings for reuse. In the first stage of this other alternative embodiment, the two-stage system includes a means for transporting the castings and the sand including a casting part entry for receiving the castings and a casting part outlet for removing the castings and also includes a means for fluidizing and heating the sand in the transport medium of the first stage to a substantially uniform heat treatment temperature. This causes the castings to be heat treated while at the same time causing the binder in the core sand within the castings to decompose so that the core sand is removed from the castings in fewer groups. of sand for males and binder. further, the first stage includes a means for transferring all the sand from the first stage transport medium which includes the core sand removed from the castings, and which includes any group of the core sand and binder, to the second stage. stage where male sand is completely recovered for reuse by completely pyrolyzing the binder while the male core is within the second stage. In the second step of this other alternative embodiment, the two-stage system comprises a means for transporting the sand including a sand inlet to receive all the sand from the sand transfer medium of the first stage and also includes a means for fluidizing and heating the sand in the transport medium of the second stage to a sand regeneration temperature. This causes the grit sand that is removed from the castings in the first stage, and that includes any group of grit sand and binder, is subjected to heat that is sufficient to completely pyrolyze the binder in the second stage to cause by this, the sand for males is regenerated for reuse. In addition, the second stage includes means for recirculating at least a portion of the sand from the transport medium of the second stage to the transport medium of the first stage after the core sand has been regenerated for reuse and, advantageously, is provide means for diverting surplus sand to a point downstream from where the sand for males has been regenerated for reuse. In a most preferred form of this other alternative embodiment, the temperature to treat with substantially uniform heat is a first selected temperature and the sand regeneration temperature is a second, higher, selected temperature sufficient to ensure that all of the binder is pyrolyzed . It is also an advantageous feature for the two-stage system to include means for transporting sand for cores formed from sand and binder from a separate location directly to the second stage to be combined with the sand of the first stage conveyor medium, which, as previously described, it includes the core sand removed from the castings as well as any group of grit sand and binder. With this arrangement of the present invention, the two-stage system can completely regenerate all core sand for reuse, including any unused or unusable male core, to completely pyrolyze the binder while the core sand is within the second stage. Since the castings have been removed, the temperature is not limited to the metallurgical specification required by the castings. Other objects, advantages and features of the present invention will become apparent from a consideration of the following specification taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a plan view of an apparatus and system for removing, regenerating and recirculating sand from a metal casting part in accordance with the present invention; Figure 2 is an elevated cross-sectional view taken generally along lines 2-2 of Figure 1; Figure 3 is an elevated cross-sectional view taken generally along lines 3-3 of Figure 1.

Figure 4 is a cross-sectional elevated view taken in generating along lines 4-4 of Figure 1; Figure 5 is a cross-sectional elevated view taken generally along lines 5-5 of Figure 1; Figure 6 is a perspective view of a pallet for supporting a plurality of metal castings as they are transformed through the apparatus and the system of Figure 1; Figure 7 is a cross-sectional elevated view similar to Figure 2 illustrating an alternative embodiment; Figure 8 is an elevated cross-sectional view taken generally along lines 8-8 of Figure 7; Figure 9 is an elevated cross-sectional view taken generally along lines 9-9 of Figure 7; Figure 10 is a plan view similar to the Figure 1 illustrating yet another alternative embodiment; Figure 11 is an elevated cross-sectional view taken generally along lines 11-11 of Figure 10; and Figure 12 is an elevated cross-sectional view taken generally along lines 12-12 of Figure 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In the illustrations given herein, and with particular reference first to Figures 1 and 4, the reference number 10 will be understood to mean in general an apparatus and system for removing and regenerating sand from a piece of metal casting according to the teachings of the present invention. As shown in Figure 1, the apparatus 10 is used to process metal castings such as 12, each having its sand mold and sand cores still in place as it follows a continuous, vibrant path which is extends from a casting load conveyor 14 to a casting part entry 16 of a fluidized bed 20 where the process is carried out. More specifically, the cast part load conveyor 14 has a casting or floor support surface 22 that is sufficiently wide to accommodate at least one metal casting piece 12, and is preferably large enough to accommodate a plurality of castings. metal castings 12 in a generally side-by-side manner (see, for example, Figure 2). As clearly illustrated in Figure 2, the support surface or floor 22 of the casting can advantageously be formed so as to have a plurality of dividers 24 extending longitudinally along the loading conveyor of the casting part. 14 so as to form a plurality of rails for transporting castings along which the metal castings 12 can be moved. Referring now to Figure 4, the support surface or floor 22 of the castings is vibrated by an unbalanced motor or eccentric driver 26 and associated springs and rocker assemblies 30 to produce vibratory forces acting generally throughout of oblique axes such as 32. In this way, the vibratory forces cause each of the sand molds containing the metal castings 12 to be transported along their respective transport rails to the fluidized bed 20 for pyrolysis the sand molds and the sand cores to regenerate the sand. Alternatively, as perhaps a superior alternative, several metal castings 12 can be placed in each of a plurality of open frame vanes 25 which can be transported on the supporting surface or floor 22 of the castings. Each of the vanes 25 (see Figure 6) for the castings 12 advantageously has a plurality of support hoppers 25a which can be defined by a square or rectangular side frame 25b and a plurality of rods 25c for dividing the vane into the 25a hoppers, and the vanes 25 may also have a plurality of rods 25d to support the castings therein. In this way, the support bins of the castings 25a of each of the blades 25 is such that it allows the hot air to pass through to fluidize the sand in the fluidized bed 20 as will be described later. Before entering the fluidized bed 20, hot sand is poured onto the sand molds containing the metal castings 12 to cover them to provide a supply of hot sand for fluidization. The hot sand is recirculated sand poured from a sand distribution conveyor 34 that will be seen to overlap the load conveyor of the casting part 14 (see Figures 4 and 5). Referring specifically to Figure 2, the side walls 36 on the loading conveyor of the castings 14 will be understood to prevent this hot sand from spilling laterally as it is transported to the fluidized bed 20. As soon as the hot sand has been supplied to the loading conveyor 14, the sand molds containing the metal castings 12 will move the sand to the fluidized bed 20 through the inlet for castings 16. As this happens, the sand molds containing the castings 12 and the sand bed surrounding and covering them will push back an entry seal for castings 40 (see Figure 4) which can be articulated from a point above the entry for castings 16 towards the fluidized bed 20. As will be appreciated from the foregoing, the seal of the entry for castings 40 serves to help retain heat within the sand in the fluidized choke 20 as the metal castings 12 are transported therethrough. As soon as the sand molds containing the castings 12 reach the fluidized bed 20, it will be understood that they move rather slowly within a heated chamber 42 along another support surface or floor of the bed 44 of the casting part from the inlet for castings 16 to the outlet of the casting piece 46. The supporting surface or floor of the bed 44 of the casting piece is preferably an uninterrupted continuation of the supporting surface or floor 22 of the casting part of the load conveyor 14, that is, advantageously comprises a single, uninterrupted and continuous vibrating surface. Thus the bearing or floor surfaces 22 and 44 of the casting can be supported by the same spring and rocking mounts and are vibrated by the same unbalanced motor or eccentric driver 26 to produce vibratory transport forces generally along axes obliques such as 32. Heating air is produced at a controlled temperature as required by the heat treatment specification in a hot air supply oven (not shown) and fed to a convector plenum 50 that extends below and substantially entirely along the support surface or floor 44 of the casting. As will be recognized by those skilled in the art, the heated air fed to plenum 50 is forced through convenient openings through and substantially entirely along the support surface or floor 44 of the casting into the sand bed that surrounds the sand molds containing the castings 12 to thereby fluidize and further heat the sand in the fluidized bed 20 and pyrolyze the resin glue material. As will also be recognized by those skilled in the art, the degree of fluidization can be varied at different points along the fluidized bed 20, if desired, alternating the temperature of the air and / or the volume of air entering the sand. , for example, by varying the size of the air openings. Since the metal castings 12 move quite slowly through the fluidized bed 20, it may be useful to control the degree of fluidization at different points along the same. Referring to Figures 7-9, an alternative embodiment of a fluidized bed 120 is illustrated for use with the remainder of the apparatus and system 10 for removing and regenerating sand from a metal casting part in accordance with the teachings of present invention. The supporting surface or floor 22 of the casting part and convective plenum 50 of the fluidized bed mode 20 best illustrated in Figure 2 has been replaced by a plurality of hot air distribution ducts 82 and hot air permeable vanes. 84 supporting the sand molds containing the cast metal pieces 12. With this alternative construction, the vanes 84 are transported through the fluidized bed 120 at the same time as they are supported on at least one pair of rails 86a and 86b carried by and connected to the upper surfaces 88 of the hot air distribution ducts 82, thereby eliminating the need for the supporting surface or floor 24 of the casting part. More specifically, it will be seen that each of the hot air distribution ducts 82 entirely encompasses the width of the fluidized bed 120 and can advantageously be rectangular in cross section (see Figure 9). The hot air distribution ducts 82 also have perforated bottom surfaces 90 in spaced relationship with the bottom surface 92 of the heated chamber 42 within the fluidized bed 120 (see Figure 8) to allow hot air to be directed towards the sand 96 surrounding the distribution ducts generally as shown by the arrows in Figure 9. The hot air will first be directed downward, then will penetrate upwardly through the sand 96 between the hot air distribution ducts 82 and through the paddles 84 causing all of the loose sand 96 to fluidize including that surrounding the sand molds containing the metal castings 12 that are being carried on the paddles 84. As will be appreciated by those skilled in the art, the size and the structure of the hot air distribution ducts 82, the degree and size of the perforation of the lower surfaces 90, the spacing ngitudinal between air distribution ducts 82, and other parameters will be within the capacity of technicians with ordinary experience who will now have a complete understanding of the inventive concept of the alternative modality illustrated in Figures 7-9. As the sand molds containing the metal castings 12 move through the heated chamber 42, the binder in the sand molds and sand cores is pyrolysed, the pyrolyzed binder is vented from the fluidized bed 20 through of ventilated piles 52 in the upper part of the furnace 42, and the reclaimed sand from the molds and cores is mixed with the fluidized sand near the metal castings 12 supported on and transported along the supporting surface or floor 44 of the casting. As will be appreciated, the unbalanced motor or eccentric driver 26 is used to move the sand molds containing the metal castings 12 through the fluidized bed 20 at different speeds. This can be desired to vary the actual time of the metallurgical treatment of the castings as well as the sand regeneration treatment within the bed for a specified time based on metallurgical considerations to ensure the proper formation of the castings as well as the removal complete of the sand molds and the sand cores of the castings and regenerate the sand. The long residence time can be achieved by using a lower first speed of the motor or impeller in which the horizontal component of the vibratory force is not sufficient to overcome the friction and other resistance to the forward movement of the transport pallets of the castings or of the castings themselves through the fluidized bed 20. The treatment period can be continued using a second higher speed of the engine or impeller to increase the horizontal component of the vibratory force to overcome the resistance to forward movement and thereby move the castings forward through the fluidized bed 20. This provides significant advantages since at the first lower engine speed or impeller the vertical component of the vibratory force significantly increases the fluidization of the sand compared to a fully static fluidized bed through which the castings can be pulled however while accommodating the desired length of residence time. As will be appreciated, the speed of moving the sand molds containing the castings 12 can be varied by changing the vibratory force or the revolutions per minute produced by the unbalanced motor or eccentric impeller 26. According to the metal castings 12 and the loose sand out of the fluidized bed 20 through the outlet of the castings 46, they push back a seal from the outlet of the castings 54. The seal of the outlet of the castings 54 is preferably articulated from above. the exit of the castings 46 and, like the seal of the entry for castings 40, helps to retain the heat inside the sand in the fluidized bed 20. The castings 12 and the loose molding sand (including that of the sand cores) regenerated by heat to pyrolyze the binder is moved through the outlet seal of the castings 54 to an exit conveyor of the former. castings 56 together with the sand originally supplied by the sand distribution conveyor 34. The outlet conveyor of the castings 56 has a support surface or floor 60 of the castings which is preferably an uninterrupted continuation of the castings. the support surface or floor 44 of the castings of the fluidized bed 20. In other words, all the support surfaces or floors 22, 44 and 60 of the castings advantageously comprise a single continuous and uninterrupted vibrating surface. As discussed in connection with the support surfaces or floors 22 and 44 of the castings, the support surface or floor 60 of the castings can be supported by the same spring and rocker assemblies and makes them vibrate the same unbalanced motor or eccentric impeller 26 to produce vibratory transport forces along generally oblique axes such as 32. The vibration of the output conveyor of the castings 56 will be understood to convey the metal castings 12 as well as the sand loose (including the one that has been regenerated) away from the fluidized bed 20. As seen in Figure 3, a portion of the loose sand which is preferably approximately equal to the volume of the sand that was present in the sand cores and / or in the sand on the outside of the metal castings 12 such as the sand mold, it is conveniently removed by an overload conduit 62. The overload conduit 62 conveniently extends from one side of the conveyor of the casting outlet 56 and has a fixed lower edge 64 to serve as a pourer at a preselected level in order to cause the proper amount of sand to be removed. As the metal castings 12 move past the overflow conduit 62, the excess sand that has resulted from removing the sand cores and / or the sand molds automatically spills out through the overload conduit 62 and takes away. to a sand cooler 66, where it is cooled and stored for reuse to make new sand cores and / or sand molds for new metal castings. After passing the overload conduit 62, the metal castings 12 and the remaining hot sand (including the one that has been regenerated) continues to move away from the fluidized bed 20 in the casting outlet conveyor 56. The remaining hot sand falls away from the metal castings 12 through the openings or one or more grooves (not shown) on the support surface or floor 60 of the castings of the exit conveyor 56 directly above a sand removal duct 70. A transfer conveyor 72 transports the collected hot sand in the sand removal duct to the return conveyor 74, which in turn returns the sand to the sand distribution conveyor 34. The sand distribution conveyor 34 generally extends transversely to the loading conveyor of the castings 14, and has an opening distribution 76 starting near the near side of the loading conveyor of the castings 14 and extending to the far side of the same Accordingly, as the hot sand is being transported along the sand distribution conveyor 34, it falls through the distribution aperture 76 onto the following metal castings 12 which are being transported on the conveyor loading of castings 14. Obviously, the sand transfer conveyor 72, the sand return conveyor 74, and the sand distribution conveyor 34 can advantageously be portions of a single enclosed and insulated continuous transport system. This entire transport system is preferably of the vibratory type described herein, although it will be understood that one or more portions of the transport system could take the form of other conventional forms of conveyors. In any case, it is important to recognize that the recirculation of hot sand through the isolated continuous transport system significantly increases the efficiency of the system while conserving the energy required to heat the sand. With respect to the metal castings 12, the casting outlet conveyor 56 continues to transport them even when the hot sand has been removed for recirculation through the sand removal duct 70. The metal castings 12 typically they will be transported by the exit conveyor of the castings 56, either individually in transport rails as previously described or in a pallet as 25, to a damping bath 78 for a conventional cooling process of castings . During the cooling of the metal castings 12, they can be transported by any conventional means including a vibratory conveyor of the type described to a pick station 80 where they can be removed. When a pallet 25 is used, a robot may place a selected number of sand molds containing metal castings 12 at predetermined locations. These places are known and correspond to where the hoppers 25a are placed in the pallet 25. After this, when the process is complete, another robot can remove the metal castings 12 from the pallet 25 since their places have not changed . With the present invention, it has become possible to exclusively use vibratory conveying means instead of roller conveyors, this remains true not only for transporting the metal castings during the removal and regeneration of the sand but also for the recirculation Of the sand. Moreover, this is done by producing a constant circulation supply of hot sand to immediately cover the sand molds containing the hot metal castings 12. By recirculating the hot sand through an insulated transport system, it is possible to reduce the The cost of the energy required to pyrolize the binder in the sand molds and sand cores since it is not necessary to completely reheat the recirculated sand. It is also noteworthy that the vibratory transport of the metal castings through fluidized sand helps to produce a uniform temperature in the sand within the fluidized bed 20. In particular, this result is improved by the vertical component of the force of the vibratory transport movement imparted to the castings in the system shown, even at the first lowest speed of the motor or impeller, as the castings are transported through the fluidized bed 20. More specifically, the component of vertical force caused by vibratory movement serves to multiply the fluidization effect by creating an even more complete mixing of the hot air with the hot sand, the hot sand with itself, and the contact of the hot sand with the sand mold, the sand cores and the castings during the sand regeneration process. As a result, it is possible to achieve a much higher efficiency of heat transfer compared to blowing or other means of forcing hot air onto the castings. Referring to Figures 10-12, yet another alternative embodiment of the present invention has been illustrated in the form of a two stage system, generally designated 200 for processing metal castings 202 and sand for cores formed of sand and binder. . The two-stage system 200 will be seen to include a first stage which is generally designated 204 for removing the sand core from the metal castings 202 and heat treating the metal castings. Referring specifically to Figure 10, the two-stage system 200 will also be seen to include a second, separate stage, which is generally designated 206, after which regenerate at least the core sand that has been removed from the castings. of metal 202 for reuse. Referring to Figure 10 which schematically illustrates the first stage 204 of the two-stage system 200, a means is provided in the form of a castings conveyor 208 having an entry for castings such as 210 for receiving the castings 202 and an output of castings such as 212 to remove the castings. The casting conveyor 208 of the first stage 204 comprises a first heated chamber 214 (see Figure 11) having a support surface 216 for the castings 202 and also having a support surface 218 for the sand 220 and , further, a first plenum 222 is provided to direct hot air first down through the holes 224 and then up through the sand 220 into the support surface 218 into the first heated chamber 214. As will be appreciated by referring to Figure 11, the first plenum 222 comprises means for fluidizing and heating the sand 220 in the conveying means 208 of the first stage 204 and, preferably, there will be a plurality of these plenums 222 arranged transversely along the length thereof. By controlling the temperature of the hot air that is administered to the first plenum 222, it is possible to heat the sand 220 in the conveying means 208 of the first stage 204 to a substantially uniform heat treatment temperature. It is possible by this to cause the castings 202 to be heat treated in the first stage 204 while at the same time the binder in the core sand inside the castings is caused to decompose so that the sand for cores Remove at least sand cores and binder from castings. As soon as the binder in the core sand has been decomposed, a transfer conveyor 226 (Figure 10) transfers all of the sand 220 from the conveying means 208 of the first stage 204 including the core sand removed from the castings 202 More specifically, the transfer conveyor 226 transfers all the sand, including any group of coarse sand and binder, to the second stage 206 to completely regenerate the cored sand for reuse, completely pyrolyzing the binder while the core sand is within the second stage 206. Referring to the second stage 206 of the two stage system 200, means are provided in the form of a sand conveyor 228 in the second stage 206 which have a second inlet as in 230 to receive all of the sand 220 from the transfer conveyor 226 of the first stage 204. The sand conveyor 228 of the second stage 206 comprises a second heated chamber 232 (see Figure 12) having a surface of support 234 for the sand, as in 236, which was received from the first stage 204 and, furthermore, a second plenum 238 is provided for directing hot air first downwards through the holes 240 and then upwards through the sand 236 on the support surface 234 to the second heated chamber 232. As will be appreciated with reference to Figure 12, the second plenum 238 comprises means for fluidizing and heating the sand 236 in the transport means 228 of the second stage 206 and, preferably, again there will be a plurality of these plenums 238 disposed along the length thereof. By controlling the temperature of the hot air that is administered to the second plenum 238, it is possible to heat the sand 236 in the transport means 228 of the second stage 206 to the regeneration temperature of the sand to completely regenerate the sand as it moves along of the transport medium 228. Preferably, the core sand removed from the castings 202 in the first stage 204, and including any group of core sand and binder, is subjected to sufficient heat to completely pyrolyze the binder in the second stage. 206 to make sand for males regenerated for reuse. As soon as the core sand has been regenerated, a generally designated sand recirculation transport system 242 recirculates at least a portion of the hot sand 236 from the conveying means 228 of the second stage 206 to the conveying means 208 of the first stage 204 which results in a substantial conservation of energy. Moreover, because the castings 202 are never present in the second, separate stage 206, it is possible to choose a sand regeneration temperature much higher than the substantially uniform heat treatment temperature required in the first stage 204. Referring once again to Figure 11, the support surface 216 defines at least one portion of continuous cast transport path extending from the entrance of the casting part 210, to and through the middle of 208, and then to the outlet of the casting piece 212. Similarly, the supporting surface 234 advantageously defines at least one continuous sand transport path portion extending from the sand entrance 230, to and through of the transport medium 228, and then to the sand outlet at 244. As shown in Figure 10, the sand transfer conveyor 226 has an upstream major section 226a placed below and transversely to the conveying means 208 of the first stage 204 for receiving sand through a duct or the like (not shown), and also having a downstream end as in 226b placed in communication with the transport means 228 for discharging sand directly in the second stage 206. As also shown in Figure 10, the sand recirculation transport system 242 has an upstream end 242a for receiving sand from the transport medium 228 of the second stage. 206 at the sand outlet 244 and has a downstream end 242b placed on top of the conveying means 208 to discharge sand directly into the first stage 204. As for other features of the two stage system illustrated in Figures 10-12, may include any convenient means for diverting surplus sand downstream of where the core sand has been regenerated for reuse in the conveying means 228 of the second stage 206. Thus, for example, the sand recirculation conveying system 242 it may include a spiral elevator 246 that receives the reclaimed sand when it is discharged into the sand outlet 244, and the spiral elevator 246 may cause the reclaimed sand to follow a helical path to an intermediate conveyor 248 which, in turn, may transport the reclaimed sand to a delivery conveyor 250. As will be appreciated from the description of other embodiments, the reclaimed sand can then be used to cover the castings 202 which are continuously introduced as in 252 in the first stage 202 in the entrance of the casting part 210 to undergo heat treatment and demoulding. As for the excess sand that is generated through the regeneration process, a collector 254 may be placed below the intermediate conveyor 248, and the excess sand may be allowed to spill from the intermediate conveyor 248 over the collector 254. And, as shown in Figure 10, it will further be appreciated that the excess sand that is spilled can then be transported away from the collector 254 to a sand cooler 255 after which it can be transported to another location for reuse since it will have been completely regenerated in the second Step 206. Although not specifically shown in Figures 10-12, it will be appreciated that the two-stage system 200 advantageously includes means for vibrating the transport means 208 and 228 of the first and second stages 204 and 206, respectively. The vibration means which can advantageously take the form of that described in relation to the other above embodiments will be convenient for transporting the castings 202 and the sand 220 in the first stage 204 generally from the entrance of the casting piece 210 towards the output of the casting part 212 and convey the sand 236 generally from the sand entrance 230 to the sand outlet 244. Also providing insulated walls 256 and 258, respectively, for the first and second hot chambers 214 and 232, the means of respective transports 208 and 228 of the first and second stages 204 and 206 can each thereby comprise an isolated vibratory fluidized conveyor. As for fluidization, as discussed previously, this is provided by directing hot air through first and second plenums 222 and 238 for passage through holes 224 and 240, respectively, which allows hot air to pass first. down and then up through the sand 220 and 236 towards the first and second heated chambers 214 and 232. In still another aspect, the embodiment illustrated in Figures 10-12 may include a sand transfer conveyor for cores 260 for transporting grit sand formed from sand and binder from a separate location such as a core space directly for the second stage 206. The males supplied from the core space can advantageously be deposited in a core inlet 262 of a vibration drum 264 that causes the males to break into groups of sand for males and binder, after which the groups are allowed to leave as in 266 on the male sand transfer conveyor 260 to be combined with the bed sand of the first stage 204, including the core sand removed from the castings 202 as well as any group of core sand and binder therein. With this arrangement for the invention, the two-stage system 200 of the present invention makes it possible to completely regenerate all the core sand in a foundry for reuse by complete pyrolization of the binder while the core sand is within the second stage 206. Since the heat treatment and demolding are presented in the first stage 204, it is advantageous for the first and second stages 204 and 206 to operate at significantly different temperatures. Thus the substantially uniform heat treatment temperature required in the first stage 204 is a first temperature selected to effectively and efficiently heat-treat the metal castings 202 while causing the males to be removed therefrom while a regeneration temperature. Much higher sand advantageously comprises a second selected temperature so that regeneration of the entire sand in the second stage 206 can be achieved to the extent that the metal castings 202 are not present in this portion of the two-stage system. steps 200. As a result, the core sand can be regenerated in a much shorter time interval and the additional heat added to the sand in the second stage 206 can be retained significantly due to the isolated nature of the two stage system 200. As for other details of the modality illustrated in Figures 10-12, it will be appreciated by the experts in the art who can utilize the corresponding aspects of the above embodiments described and illustrated in Figures 1-9. It will also be appreciated that the hot air to be administered to the first and second plenums 222 and 238 can be provided by a common furnace or two separate furnaces, the latter probably being preferable. In addition it may be desirable to use a furnace which delivers an oxygen-poor gas to the first plenum 222 in order to inhibit the combustion of the binder to maintain a substantially uniform heat treatment temperature. Conversely, with respect to the second heated chamber 232, a different furnace may be used to provide an oxygen rich environment to the second plenum 238 at an elevated temperature in order to ensure complete combustion of the binder to facilitate the regeneration of sand for reuse. As will also be appreciated, many of the construction details may take a variety of different forms that will be readily apparent to one skilled in the art and, thus, are not important in understanding the inventive concept. For example, in addition to the conveying means 208 and 228, some or all of the other conveyors including the sand transfer conveyor 226, the spiral elevator 246, the intermediate conveyor 248, and the management conveyor 250 may be vibratory isolated conveyors for transport sand while at the same time promoting energy efficiency by retaining the heat that has been added to the sand by the hot air supplied through the plenums 22 and 238. Furthermore, it will be understood that conventional heat sealing techniques can be used in ways that are known in the art to retain heat as the sand moves from one portion of the two-stage system to the other. As for the operation parameters such as capacities, temperatures, processing times, lengths of the conveyors, and the like, these depend on the particular application and are clearly within the capacity of those skilled in the art. Because of the present invention, the uniformity of the heat in the transport sand and, thus, the efficiency of heat transfer has been maximized, in an apparatus and systems that have truly unique attributes in relation to any apparatus and systems known hitherto. Although preferred embodiments of the invention have been presented in the foregoing, it will be appreciated that the details given herein may be varied by those skilled in the art without departing from the true scope and spirit of the appended claims.

Claims (27)

1. An apparatus for removing and regenerating sand from metal castings, comprising: a means defining an entrance for castings to receive castings and an outlet for castings for removing castings, - a means that forms a bed for the sand and a means for supplying sand to said bed near the entrance of the castings thereof; a means for directing a hot gas through the sand in the bed to thereby heat and fluidize the sand; and means for removing the sand from the bed near the outlet of the casting for recirculation at the entrance of the castings.

The apparatus of claim 1 wherein the medium forming the bed comprises a heated chamber having a lower surface for supporting the sand, and the means for directing the hot gas through the sand includes a plurality of distribution ducts. of hot gas, each of the hot gas distribution ducts encompasses the width of the bed in longitudinally spaced relation therealong.

The apparatus of claim 2 wherein each of the hot gas distribution ducts is generally rectangular in cross section having upper and lower surfaces, and including a hot gas permeable paddle to support sand molds containing the pieces casting metal on rails carried by the upper surfaces of the ducts and further include means for vibrating the bed to transport the pallet on the rails from the entrance of the casting to the exit of the casting.

The apparatus of claim 3 wherein each of the ducts has a perforated bottom surface disposed in spaced relationship with the bottom surface of the heated chamber.

The apparatus of claim 1 wherein the medium forming the bed comprises a heated chamber having a supporting surface, and a plenum for directing hot air upwardly through the supporting surface towards the heated chamber, having the The surface supports a plurality of dividers forming a plurality of transport rails extending longitudinally through the bed.

The apparatus of claim 5 wherein the support surface defines an uninterrupted, continuous transport path, leading from a load conveyor, to and through the bed, and then to an outflow conveyor, the delivery means comprising a distribution conveyor having a distribution opening on top of the loading conveyor upstream of the entrance of the casting piece towards the bed, the sand removal means comprising a transfer conveyor communicating with a removal duct beneath the conveyor outlet downstream of the outlet of the casting piece towards the bed.

The apparatus of claim 1 including a means for deflecting surplus sand comprising an overflow conduit extending from one side of the bed-forming means and having a lower edge defining a sand dump to a level preselected for the sand inside it.

The apparatus of claim 1 including means for recirculating sand from the outlet of the casting piece to the entrance of the casting including an insulated conveyor extending from the sand removal means to the supply means of sand to recirculate the heated sand to fluidize in the bed.

The apparatus of claim 1 including a vane for supporting a plurality of metal castings, the vane having a plurality of support chutes for castings, allowing the hoppers to support the castings that the air hot fluidize the sand in the bed.

The apparatus of claim 1 including means for vibrating the bed to produce vibratory forces to transport the castings from the entrance of the castings to the exit of the castings and further fluidize and also transport the sand from the entrance of the castings to the exit of the castings.

11. An apparatus for removing and regenerating sand from a piece of metal casting, which comprises: a fluidized conveyor bed having a cast part entry for receiving the casting part and a casting part outlet for removing the casting part; a casting load conveyor leading to the entry of castings of the fluidized conveyor bed to transport the casting piece thereto; a sand distribution conveyor for supplying sand to be recirculated through the fluidised conveyor bed, the distribution conveyor having a sand distribution opening positioned at a point generally above the load conveyor of the casting, the sand distribution opening upstream of the inlet of the casting part of the fluidized conveyor bed; means for heating and fluidising sand in the fluidized conveyor bed by directing the hot gas therethrough, - an outlet conveyor for the casting part leading from the outlet of the casting part of the fluidized conveyor bed to transport the piece of iron. casting therefrom, - a sand transfer conveyor communicating with a sand removal duct placed at a point generally below the cast part exit conveyor, - an overload duct extending from one side of the conveyor of exit of the casting piece near the outlet of the casting part of the fluidized conveyor bed; and a sand return conveyor extending from the sand transfer conveyor to the sand distribution conveyor to recycle sand therethrough.

The apparatus of claim 11 wherein the means for heating and fluidizing the sand in the fluidised conveyor bed by directing hot gas therethrough includes a plurality of longitudinally spaced hot gas distribution ducts that span the width of the fluidized conveyor bed each of the gas distribution ducts being generally rectangular in cross section having an upper surface and also having a perforated bottom surface arranged in spaced relationship with a lower surface of a heated chamber defined by the fluidized conveyor bed, and including a hot gas permeable vane to support sand molds containing metal castings on rails carried by the upper surfaces of the ducts.

The apparatus of claim 11 wherein the fluidised conveyor bed comprises a heated chamber for removing a sand regeneration, a plenum for providing hot air to the heated chamber, and a casting support surface as a grid separating the chamber heated from the plenum, the fluidized conveyor bed having a casting support surface with a plurality of dividers forming a plurality of conveyors for transporting castings extending longitudinally through the fluidized conveyor bed, defining the supporting surface of the casting part a continuous, uninterrupted transport path, which leads from the loading conveyor of the casting piece, to and through the fluidized conveyor bed, and then to the outlet conveyor of the casting part.

The apparatus of claim 11 wherein the sand distribution conveyor extends generally transversely of the load conveyor of the casting part and the sand distribution opening is extended from a near side to a far side of the load conveyor of the casting part.

The apparatus of claim 11 wherein the overflow conduit has a lower edge defining a weir at a preselected level to accommodate the removal of excess sand created by removing sand from the casting in the fluidized conveyor bed.

16. The apparatus of claim 11 including an articulated casting entry seal from a point above the inlet of the casting part of the fluidized conveyor bed and also includes an articulated casting outlet seal from a point above the outlet of the casting part of the fluidized conveyor bed.

The apparatus of claim 11 which includes means for vibrating the fluidized conveyor bed to transport the castings of metal in the vane from the entry of castings to the exit of castings together with the sand received from the sand distribution conveyor.

18. A vibration sand regeneration system for removing and regenerating sand from a piece of metal casting, comprising: a fluidized conveyor bed having an entry of castings to receive the casting and an outlet of castings to remove the casting piece; the fluidized conveyor bed comprises a heated chamber for removing and regenerating sand, a plenum for providing hot air to the heated chamber, and a casting support surface separating the hot chamber and plenum, the workpiece support surface The casting comprises a plate as a grid through which the hot air is forced to fluidize and heat the sand as the casting is transported from the entrance of the casting to the exit of the casting; a vibratory conveyor for loading castings leading to the entry of castings of the fluidized conveyor bed to transport the casting part thereto; a vibratory sand distribution conveyor for supplying sand to be recirculated through the fluidised conveyor bed, the sand distribution conveyor having a sand distribution aperture positioned at a point generally above the load carrier of the casting, the sand distribution opening upstream of the inlet of the casting part of the fluidised conveyor bed being arranged, the sand distribution conveyor being enclosed and insulated to retain the heat in the sand to be recirculated through the conveyor bed fluidized; a vibratory conveyor for exiting the casting part leading from the outlet of the casting part of the fluidized conveyor bed to transport the casting part therefrom; the support surface of the casting part comprises a continuous, uninterrupted vibrating surface defining a continuous transport path leading from the load conveyor, to and through the fluidized conveyor bed where the support surface of the casting comprises the grid-like plate, and then to the outlet conveyor of the casting; a vibratory sand transfer conveyor that communicates with a sand removal duct placed at a point generally below the outlet conveyor of the casting, the sand transfer conveyor is enclosed and insulated to retain heat in the sand for recirculate through the fluidized conveyor bed; an overflow conduit extending from one side of the outlet conveyor of the casting piece nthe outlet of the casting part of the fluidized conveyor bed; and a vibratory sand return conveyor extending from the sand transfer conveyor to the sand distribution conveyor to recirculate sand therewith, the return conveyor being enclosed and insulated to retain heat in the sand to recirculate through of the fluidized transport bed.

19. A two-stage system for processing metal castings and sand for cores formed of sand and binder, which includes a first step to remove the core sand from the metal castings and heat treat the castings metal, and that includes a second, separate stage to regenerate by this at least the core sand removed from the metal castings for reuse, the system comprises, in the first stage: means for transporting the castings and sand in the first stage and including an entry for the casting to receive the castings and an outlet for castings to remove the castings; means for fluidizing and heating the sand in the transport medium of the first stage to a substantially uniform heat treatment temperature to thereby cause the castings to be heat treated while at the same time causing the binder in the sand to males within the castings decompose so that the core sand is removed from the castings in at least groups of sand for cores and binder; and means for transferring substantially all of the sand from the transport medium from the first stage to the second stage including the core sand removed from the castings, and including at least groups of the core sand and binder, to completely regenerate the sand for males for reuse, completely pyrolizing the binder while the sand for males is within the second stage; the system comprises, in the second stage: means for transporting the sand in the second stage and including a sand inlet to receive all the sand from the sand transfer medium of the first stage; means for fluidizing and heating the sand in the transport medium of the second stage to a sand regeneration temperature for by this causing the sand for males removed from the castings in the first stage, and which includes any group of the sand for cores and binder, is subjected to sufficient heat to completely pyrolyze the binder in the second stage to make the core sand regenerate for reuse; and means for recirculating at least a portion of the sand from the means of transport of the second stage for the means of transport of the first stage after the sand for males has been regenerated for reuse.

The two-stage system of claim 19 wherein the conveying means of the first stage comprises a first heated chamber having a support surface for the castings and a support surface for the sand and a first plenum for directing hot air upwards through the sand to the first heated chamber, and the means of transport of the second stage comprises a second heated chamber having a support surface for the sand of the first stage and a second plenum for directing air Warm up through the sand to the second heated chamber.

21. The two-stage system of claim 20 wherein the support surface of the castings of the first stage defines at least a portion of a continuous transport path for castings, the continuous transport path for castings extending from the entrance of the castings , towards and through the means of transport of the first stage, and then towards the exit of the castings, and the sand supporting surface of the second stage defines at least a portion of a continuous transport path of sand, extending the continuous transport path of sand from the sand transfer medium, to and through the means of transport of the second stage, and then to the sand recirculation means.

22. The two-stage system of claim 19 wherein the sand transfer means comprises a sand transfer conveyor having a larger upstream section positioned to receive sand from the first stage transport means having one end. downstream positioned to transfer sand to the second stage transport means, and the recirculation means comprises a sand recirculation conveyor having an upstream end positioned to receive sand from the second stage transport means and having a end downstream placed to transfer sand to the transport medium of the first stage.

23. A two-stage vibratory system for processing metal castings and sand for cores formed of sand and binder, which includes a first vibratory stage to remove the sand for cores from the metal castings and to treat the pieces by heat metal casting, and including a second vibratory stage, separated to regenerate by this at least the core sand removed from the metal castings for reuse, the system comprises, in the first vibratory stage: means for transporting the castings and sand in the first vibratory stage and including an entry for the casting to receive the castings and an outlet for castings to remove the castings; means for fluidizing and heating the sand in the transport medium of the first vibratory stage to a substantially uniform heat treatment temperature so as to cause the castings to be heat treated while at the same time making the binder in the sand for males within the castings decompose so that the core sand is removed from the castings in at least groups of sand for cores and binder; the means for transporting the first vibratory stage comprises a first heated chamber having a support surface as a grate for the castings and a supporting surface for the sand and a first plenum below the supporting surface as a grid for directing air hot up through the sand to the heated first chamber and including means for vibrating the transport means of the first vibratory stage to transport the castings and the sand generally from the entrance of the castings to the outlet of the castings, - the vibration means of the first vibratory stage producing vibratory forces for transporting the castings and the sand generally from the entrance of the castings to the exit of the castings, - and means for transfer substantially all the sand from the means of transport of the first vibratory stage to the nda vibratory stage including the grit sand removed from the castings, and which includes at least groups of the grit sand and binder, to completely regenerate the grit for reuse by completely pyrolizing the binder while the grit sand is within the second vibratory stage; the transfer means is in communication with the means of transport of the second vibratory stage between the entry of the castings and the exit of the castings; the system comprises, in the second vibratory stage: means for transporting the sand in the second vibratory stage and including a sand inlet to receive all the sand from the sand transfer medium of the first stage, - means for fluidizing and heating the sand sand in the transport medium of the second vibratory stage at a sand regeneration temperature to by this cause the sand for males removed from the castings in the first stage, and that includes any group of the sand for males and binder , undergo sufficient heat to completely pyrolyze the binder in the second vibratory stage to make the core sand regenerate for reuse; the means of transport of the second vibratory stage comprises a second hot chamber having a support surface for the sand from the first vibratory stage and a second plenum for directing hot air up through the sand to the heated second chamber and includes means for vibrating the transport means of the second vibratory stage to transport the sand generally from the sand inlet to the sand outlet; the vibratory means of the second vibratory stage produce vibratory forces to transport the sand generally from the sand entrance to the sand outlet to recirculate at least a portion of the sand, and means to recirculate at least a portion of the sand from the middle. of transport of the second vibratory stage for the means of transport of the first vibratory stage after the sand for males has been regenerated for reuse; the recirculation means are in communication with the conveying means of the second vibratory stage generally at the sand outlet of the conveying means of the second vibratory stage.

The two-stage vibratory system of claim 23 wherein the substantially uniform heat treatment temperature is a first selected temperature and the sand regeneration temperature is a second selected higher temperature.

25. The two-stage vibratory system of claim 23 including means for transporting the sand for cores formed of sand and binder from a separate location directly to the sand inlet of the second stage, to be combined with the sand of the bed of the second stage. first stage, which includes sand for males removed from the castings, and which includes any group of sand for males and binder, to completely regenerate the sand for males for reuse by completely pyrolyzing the binder while the sand for males is within the second stage.

26. The two-stage system of claim 23 including means for diverting surplus sand downstream of where the core sand has been regenerated for reuse.

27. The two-stage system of claim 23 wherein the means of transporting the first and second stages each comprises an isolated vibratory fluidized conveyor.