Abstract:
An offset conveyor system utilizes a lower conveying section positioned adjacent a pouring station where molten metal is poured into weighted and jacketed sand molds. Molds are transported on carriers along the lower section from a mold loading station to a weight and jacket placement station to the pouring station. After pouring, the carrier with jacketed mold is moved up an incline to an upper conveying section parallel the lower section and may overlap the lower section partially. Molds are transported in an opposite linear direction relative to the lower section to a weight and jacket removal station and to a mold dump station, where the sand mold and casting are removed from the conveyor. The carrier is returned to the lower conveyor section to receive another mold. The weight and jacket removed from the upper section is placed on a mold on the lower section, therefore only a minimum number of weights and jackets are used. The mold carriers may be dimensioned to carry sand molds in side by side relation thus, castings may circulate more than one circuit on the conveyor to permit additional cooling and solidification if necessary or multiple pourings may be accomplished.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of foundry operations and more particularly to the field of castings wherein conveyors are utilized to move sand molds to various stations along a casting line. In greater particularity, the present invention relates to a casting line utilizing a weight and jacket about the sand molds and a pouring line as well as a discharge line. In still further particularity, the present invention relates to a conveyor system wherein the pouring line and discharge line are at different elevations and to the mechanism for handling castings and molds on said conveyor. 
     BACKGROUND OF THE INVENTION 
     The art of casting metal objects in sand molds is ancient. Numerous advances have been made in the art including the automation of the process and the integration of conveyors into the process. Certain elements of casting are invariable, thus one of the problems is to adapt the environment in which the castings are made to fit the available resources. One increasingly evident factor is cost. As the cost per square foot of building space increases, the casting line becomes more expensive. Likewise, the greater cost of installation yields a reduced likelihood of adoption of a particular line. Numerous patents have addressed the problems associated with the space limitation as well as the time limitation. That is to say, a conveyor has to have sufficient length to allow a molten casting to solidify before the casting can be discharged, thus a continuously operated conveyor has a finite number of incremental movements between the time the casting is poured and the casting is discharged. The cumulative dwell time of a casting on the incremental positions must equal the length of time required before the casting can be discharged. Where space is not a problem, the casting line could be any length needed, however, space is generally a problem. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an automated casting line having minimal floor space requirements and minimal installation requirements in terms of site preparation. 
     Another object of the invention is to provide a system, which permits ready access to the various stations for maintenance and repair. 
     These and other objects of the invention are provided by an offset conveyor system wherein a lower section of the conveyor is positioned adjacent a pouring station where molten metal is poured into weighted and jacketed sand molds. Molds are transported on carriers along the lower section from a mold loading station to a weight and jacket placement station to the pouring station. After pouring, the carrier with jacketed mold is moved upwardly to an offset upper conveyor section that is parallel the lower section and may overlap the lower section partially. Molds are transported in an opposite linear direction relative to the lower section, to a weight and jacket removal station and to a mold dump station, where the sand mold and casting are removed from the conveyor. The carrier is returned to the lower conveyor section to receive another mold. The weight and jacket removed from the upper section is placed on a mold on the lower section, therefore only a minimum number of weights and jackets are used. The mold carriers may be dimensioned to carry sand molds in side by side relation, thus castings may circulate more than one circuit on the conveyor to permit additional cooling and solidification if necessary. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Apparatus embodying the features of my invention are depicted in the accompanying drawings which form a portion of this disclosure and wherein: 
     FIG. 1 is a perspective view of the system; 
     FIG. 2 is a side elevation of the system; 
     FIG. 3 is a detailed view of the elevator system; 
     FIG. 4 is a detailed view of a second embodiment of the elevator system; 
     FIG. 5 is a detailed view of a third embodiment of the elevator system; 
     FIG. 6 is a detailed view of a fourth embodiment of the elevator system; 
     FIG. 7 is a view of the drive system; and 
     FIG. 8 is a view of the jacket shift and frame. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings for a clearer understanding of the invention it will be seen in FIG. 1, that the present invention is a conveyor system on which molds are transported, filled with molten metal and discharged after the molten metal has sufficiently cooled to permit removal of the mold and subsequent handling. The present invention permits pouring of the molten metal at a lower location and discharging the metal at an upper location, hence eliminating the need for an excavated pit at the discharge location. Accordingly, the conveyor  10  includes a lower conveyor section  11  defined by a set of parallel linear tracks  12  of a selected length and an upper conveyor section  13  defined by a set of parallel linear tracks  14  of an equivalent length. As will be understood, the cooling of metal poured into a mold requires a certain passage of time, thus tracks  12  and  14  must be long enough to permit cooling. Supported on the tracks are a plurality of mold carriers  16 , each defined by an upper platform  17  supported on a plurality of wheels  18  which are positioned to ride along tracks  12  and  14 . The wheels may be flanged or may be caster wheels with rail guides as are known in the art. It is possible that the tracks could be replaced with roller conveyors with appropriate flat-bottomed carriers. Such a system would require appropriate side guides and stops in the various stations. The upper surface of the platforms is substantially flat to receive formed sand molds  21  thereon at a loading station  31 . As will be understood, the sand molds  21  are formed with any suitable mold making machinery and are slid onto platform  17  in position on the carrier to subsequently be filled with molten metal. The carriers  16  are not interconnected but rather abut at their forward and trailing ends. Platform  17  may be dimensioned to receive a single sand mold, however, it is often desirable to retain more than one mold on the carrier to enable a longer cooling time for the molten metal. Therefore the platform dimension is preferentially sufficient to accommodate three molds thereon without interference between the molds. 
     The carriers  16  on lower section  11  are all moved concomitantly by a linear actuator  75   a  or rotary actuator  75   b , as shown in FIGS. 3 and 6, which will be described hereinafter, such that each carrier  16  may be brought into alignment with loading station  31  to receive a fresh sand mold  21 . Thus, either actuator  75   a  or  75   b  may be used to move the carriers one carrier length at a time. Prior to pouring molten metal into the sand molds  21 , the molds must be encased within a weight and jacket assembly  22  as is well known in the art. In the preferred embodiment, the weight and jacket assembly  22  is removed from a sand mold  21  on upper conveyor  13  and placed on a waiting mold  21  on lower conveyor  11 . Thus, a weight and jacket shifter  41  is provided including a frame  42  extending transverse to conveyor  11  and  13  at a height sufficient to allow a weight and jacket  22  to be lifted off a sand mold  21  on conveyor  13  and moved laterally. Frame  42  extends over conveyor  11  sufficiently to. allow the weight and jacket removed from conveyor  13  to be lowered to encase a sand mold  21  supported on conveyor  11 . As is understood, weight and jacket  22  have a formed aperture  23  therein to permit pouring of molten metal into mold  21 . To accomplish the movement of the weight and jacket assembly, a cross shuttle  43  is mounted to frame  42  and moves linearly on a set of rails or guides  44  engaged by either shuttle wheels  45  or a slide. The shuttle may be conventionally driven in any suitable manner, such as by a controllable linear actuator that provides accurate positioning, by a worm gear or by a stepper motor mounted to shuttle  43 . Since the drive mechanisms are all well known, the drive is shown generically in FIG.  1 . Mounted to shuttle  43  is a gripping assembly or magnetic engagement assembly  50  which is movable vertically under the control of a hydraulic cylinder  46  to engage, lift, lower, set, and release the weight and jacket  22 . Such assemblies  50  are well known in the art and may be of any commercially acceptable configuration, which can engage and support the weight and jacket assembly. 
     After the weight and jacket  22  are placed on the mold  21 , the line of carriers  16  is advanced to bring the next empty mold to the pouring station  61 . At this station a manual or automated pouring process introduces molten metal through the formed aperture into the empty sand mold. Commercially available robotic ladle handling units  62  can be used to repetitively pour molten metal obtained from a furnace, shown schematically for illustrative purposes only. If manual pouring is desired, an appropriate platform  64  and ladle track may be constructed adjacent lower conveyor section  11  at the pouring station  61 . Once the metal has been poured into the mold, the conveyor is indexed, bringing a fresh mold to the pouring station and moving cooling molds away from the pouring station. At the end of conveyor  11  is an elevator  71  which receives a mold carrier  16 , mold  21 , and weight and jacket  22  on an elevator platform  72  on which a cooperative track  73  is supported. A set of stops  74  secures the mold carrier against inadvertent movement while on the elevator. The elevators, preferably, take the form of a parallelogram linkage  75 , as shown in FIGS. 3 and 6, having a horizontally disposed platform  72  movable selectively between positions adjacent the conveyors  11  and  13  for receiving and discharging mold carriers therefrom. Parallelogram linkage  75  is selectively movable between the conveyors by a linear actuator  75   a  as shown in FIG. 3 or by a rotary actuator  75   b , partially shown in FIG.  6 . Rotary actuator  75   b  includes a reversible motor  103  of any suitable type, which has an output shaft  104  which rotates through an arc B and concomitantly moves an attached arm  105  through the same arc. Arm  105  is attached to linkage  75  to selectively move the linkage between upper and lower conveyors. 
     Alternatively, the elevator platform  72  may move on an inclined guide track  76  between a lower position aligned with conveyor  11  and an upper position aligned with conveyor  13 . As seen in FIGS. 4 and 5, a linear actuator  78 , or a worm gear  79 , or any suitable source of motive power which can supply a smooth and repeatable movement between the upper and lower positions. It will be appreciated that platform  72  and track  73  must accommodate the carriers on conveyors  11  and  13 , thus the elevator may need to transport three castings at once on a mold carrier. 
     Once a carrier  16  is elevated to conveyor  13 , the driver mechanism urges the carrier from the elevator platform onto track  14 , thereby indexing the carriers on the track. It will be appreciated that a lowering elevator  81  at the opposite end of conveyor  14 , having the same features as elevator  71 , must be in position to receive a carrier  16  on a set of rails  83  supported on a platform  82  when the carriers are indexed along conveyor  14 . Elevators  71  and  81  must therefore move concomitantly between upper and lower positions to ensure that the mold carriers are properly indexed to and from the conveyors. 
     When a mold carrier  16  bearing a weighted and jacketed mold and casting on conveyor  13  reaches a position parallel the weight and jacket station  41  of conveyor  11 , it will be in position beneath the upper reach of station  41  such that the engagement assembly  50  can engage and lift the weight and jacket from the mold for placement on a fresh mold on lower conveyor  11 . After the carrier is indexed beyond this station, a mold shifter  91  is employed to move the mold and internal casting laterally. If the carrier  16  is dimensioned to support only one mold, then the lateral movement urges the sand mold and metal casting off the conveyor onto a shake out conveyor  101  wherein the sand and casting are separated with the sand sent to a reclaim process and the casting conveyed for further processing such as deburring and spur removal. If the carrier  16  is wide enough to accommodate more than one mold  21 , then the lateral movement moves one mold off the conveyor  13  onto shakeout conveyor  101  and moves the remaining mold and casting laterally sufficiently to accommodate a new mold when the carrier is returned to the mold loading station. Accordingly, the mold shifter  91  is designed to accommodate the width of the carrier, however, shifter  91  will be essentially a movable panel (not illustrated) urged across the top of the carrier by a cylinder (not illustrated) such that substantially all of the sand is moved by a lateral force applied to the mold. It will be appreciated that the same type mold shifter will be used to load sand molds and that such mold shifters are of conventional design. 
     The indexing of the carriers  16  on conveyors  11  and  13  is accomplished using a pusher type hydraulic cylinder assembly  111  or a rotary actuator  102 . In FIG. 6 it may be seen that rotary actuator  102  is similar to actuator  75   b  and comprises a motor  103  which may be hydraulic or electrical. Motor  103  is reversible and controllable. Motor  103  has an output shaft  104 , which rotates through an arc A and concomitantly moves an attached arm  105  through the same arc. Arm  105  carries a cross bar  106  which abuts carrier  16 . Arc A is intended to move cross bar  105  and carrier  16  one carrier length, thereby moving the entire sequence of carriers on the conveyor one carrier length. It will be appreciated that an actuator  102  is associated with each conveyor  11  and  13 . In another embodiment, -a cylinder  110  is mounted vertically adjacent elevator platform  72  to move assembly  111  concomitantly with and adjacent elevator platform  82 . In fact the cylinders may be mounted on a frame  114 ,  114 ′. Each assembly has a cylinder  112 ,  112 ′ and rod  115 ,  115 ′ that engages a pivotally mounted substantially dogleg frame  116 ,  116 ′. The frame  116 ,  116 ′ is supported at an upper end  116   a  for rotation about a horizontal axis, with the lower end affixed to a horizontally disposed pusher bar  117 ,  117 ′. Bar  117  engages a carrier  16  on lowering elevator platform  72  to urge carrier  16  and each adjacent carrier on conveyor  11  horizontally responsive to downward movement of rod  115 . Concomitantly, rod  117 ′ moves horizontally responsive to the upward movement of piston rod  115 ′. The rods  117 ,  117 ′ may thus stabilize the line of carriers and assist in positioning the carriers in the various stations. Likewise, when elevator  72  has conveyed a carrier  16  to upper conveyor  13 , rod  117 ′ engages the carrier  16  and urges the carrier and adjacent carriers horizontally along conveyor  13  responsive to downward movement of rod  113 ,  113 ′. Alternative triangular frame  116  and cylinder  110  may be supported on platform  72 ,  82 . 
     It will be appreciated that the mold carriers are circulated from the lower carrier to the upper carrier and back again, and those sand molds initially enter the circulating carrier loop on the lower carrier. If each carrier had more than one mold thereon, then a mold with a cooling casting therein moves on conveyor  11  from the pouring station to elevator  72  to conveyor  13  to mold shift station  91  at which point the mold is moved laterally, then to lowering elevator  82  to carrier  11 , to elevator  72 , to conveyor  13  to the shift station, whereupon the mold and casting are discharged to shakeout conveyor  101 . If more than two molds are supported on each carrier then each mold may be carried through another cycle for extended cooling. In the multimold per mold carrier arrangement, the inboard mold on the mold carrier could be partially or completely subjacent the inboard mold carrier of the upper conveyor, thus affording a savings of installation space. 
     In yet another embodiment, each carrier supports two sand molds in side by side relation. The molds are loaded at the mold loading station in tandem. The pouring station utilizes two pouring robots, such that both molds are filled with molten metal. If necessary the inboard mold may be filled first and the outboard mold filled second or the inboard and outboard molds on adjacent carriers may be filled. When the carriers are moved to the upper conveyor the outboard mold (inboard on lower conveyor) is off loaded first onto the shakeout conveyor. Since the upper and lower conveyors are offset, the pouring station and weight and jacket station can operate without interference from the upper conveyor. For castings that are amenable to shakeout after one pass on the conveyor, the dual filling capability effectively doubles the capacity of the system with minimal increase in space and equipment. Further, the height of the upper conveyor can be such that no excavation is needed to install the shakeout conveyor. Use of the articulated drivers likewise reduces the space required to install the system. Accordingly, a much smaller footprint and much less costly installation is possible with the present invention. 
     While the apparatus has been disclosed in various forms, these are intended as illustrations rather than limitations, and the intended scope of the invention is set forth in the claims.