Abstract:
An improved a sand casting line where in sand molds are carried on cars along at least a first and second linear parallel yet opposing paths, including an endless loop conveyor positioned proximal a discharge end of one of the linear paths and a loading end of the other of the linear paths, with a plurality of car supporting elements carried thereon, such that a car can be discharged from the discharge end on to a supporting element simultaneously with a second car being loaded from a supporting element onto the loading end.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    In the field of sand mold casting of metal objects, existing technology generally uses a system where mold supporting cars carry preformed sand molds along a path to allow pouring of molten metal into the molds and cooling of the metal in the mold into a casting. The cars are indexed along rails by pushing car against car as a group, typically moving one car-length at a time. 
         [0002]    At the ends of each row, the last car moves onto an end transfer device, usually a transfer carrier moving along a track at 90 degrees to the main rail lines. The transfer device moves to align with the adjacent rails, and the mold car is pushed in the opposite direction, along with the cars already on that line. The system can consist of just 2 parallel rail lines, as shown on the attached drawings, moving in opposite directions, or multiple lines can be used for more cooling time. 
         [0003]    With the currently used designs, the end transfers require that both transfer carriers be lined up with the same set of rails, with one end transfer carrier empty, so that when the row of mold cars indexes moving the mold car from the end transfer carrier to the rail line, there is an empty space on the transfer carrier at the other end to receive a mold car. Then the empty end transfer carrier must move back to the adjacent rail line to receive the next indexed car. This system only allows one line of mold cars to move at a time, because there is no end transfer carrier lined up with the other rail line. This limits the cycle time and thus the speed of the system. 
         [0004]    Another disadvantage of these systems is created by the large amount of molding sand which typically falls into the end transfers as the end transfer moves with a mold car on it. The sand comes from the “crumbling” of the molds as the hot metal inside destroys the bonding on the sand. Because there are rails, supports, and motion mechanisms under the end transfers, the sand that falls is difficult to remove, especially during production. As dropped sand builds up, it may prevent the end transfer carrier from moving properly, causing production stoppage for cleaning out the end transfer. 
         [0005]    The speed of movement of the molds through the pouring station and along the cooling lines can be increased by improving the cross transfer mechanism. 
         [0006]    The productivity of the casting system can also be increased by reducing the accumulation of sand in the cross transfer area and reduce the amount of time required to remove sand from this area. 
         [0007]    With the new transfer device, an endless chain with rails to support the mold cars, moves across the system with the mold car to move it to the adjacent rail line. The chain always moves in the same direction, and has multiple sets of the rails affixed on it, so that when the chain stops there are sets of rails lined up with both (or all) of the rail lines. This allows all of the mold car lines to index simultaneously, improving cycle time. 
         [0008]    In addition, the chains are fitted with wipers between the sets of rails, or the rails themselves used as wipers, which will push the spilled sand which has fallen through the open chains, out to one side of the end transfer. A spill pan mounted underneath the chains to catch the sand to allow the wipers to continually clean the pan. This will prevent sand buildup, and facilitate cleanup, outside of the end transfer at a single point. 
         [0009]    These and other advantages will become apparent from the following detailed description of the preferred embodiment of the apparatus. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    An improved casting conveyor is depicted in the accompanying drawings which form a portion of this disclosure and wherein: 
           [0011]      FIG. 1  is a plan view of a casting system; 
           [0012]      FIG. 2  is a plan view of the improved end conveyor for the casting system; and 
           [0013]      FIG. 3  is an elevation view of the chain driven cross transfer system; and 
           [0014]      FIG. 4  is an end view of the chain driven cross transfer system. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0015]    Referring to the  FIGS. 1-4  for a clearer understanding of the apparatus, it may be seen that the preferred embodiment of the apparatus contemplates a conventional cooling line  11  which may include a pouring line  12  along one side thereof proximal which a series of manual or automatic pouring stations, not shown, are located. A plurality of mold cars  14  are mounted on parallel rails. In the illustrated embodiment, each car  14  supports three sand molds  16  previously formed as is well known in the art. Each mold car  14  is driven along the tracks conventionally by hydraulic pushers or other motive means as is well known in the art. 
         [0016]    As will be understood, a weight and mold shifting station  18  using conventional apparatus is provided up stream of the pouring stations. The pouring stations are adjacent the molds indicated by the letter P in the drawing. A conventional weighted jacket  20  is placed on the outer most sand mold  16  on each car  14  before entering the pouring station. The jackets are removed in the weight and mold shifting station  18  when the car  14  returns thereto after passing through the pouring station  12  and along an initial cooling interval. 
         [0017]    Referring to  FIGS. 2 &amp; 3 , it will be seen that the improved transfer system utilizes an endless chain conveyor having at least two chains  24  driven around sprocket pairs  26  and  28  by motor  30 . Further, one or more idler sprockets  31  may be necessary to provide support to the chains  24  along their length. Motor  30  is precisely controlled to advance the chains  24  incremental distances. On selected links of the chains  24  rail sets  32  are bolted, welded or otherwise affixed transversely connecting chains  24  and defining movable rail extensions to the rails supporting cars  14  in the casting line. It will be understood that the term rail set is intended to encompass any profile rail for engaging a supporting wheel of car  14  and is intended to encompass any runner or support for a wheel or caster used to support car  14 . Thus, the variations shown in the  FIG. 3  are not intended to be limiting with respect to the sectional profile of the rail or the type wheel used to support car  14 . Likewise, chains  24  may be interchanged with belts, cogged or other wise adequately controllable, and capable of supporting the cars  14  in the same manner as chains  24 . 
         [0018]    A combination of control technology including limit switches or proximity sensors and motor controllers may be employed to advance the chains  24  carrying the rail sets  32  into position to align with the rails supporting the cars in casting line  11 . It will be understood that the precise location of such control elements will be determined by the location and operational characteristics of such devices which are considered to be engineering choices rather than inventive concerns. Irrespective of the type control units, it will be understood that a programmable controller or other computer control, utilizes sensed position information relative to the rail sets to prevent the cars from being advanced at any time the rail sets are not aligned with the rails supporting the line of cars. 
         [0019]    A pan or catch basin  36  extends beneath chains  24  sufficiently to catch any loose sand falling from the cars  14  as they transition onto rail sets  32  or are moved between positions relative to the casting line. Pan  36  is located proximal the lower run of chains  24  and opens to a recovery bin at one side of the casting line. Affixed to links of chains  24  intermediate the links supporting rail sets  32  is at least one wiper or blade  40  which moves with the chains  24  along pan  36  to urge sand accumulated in the pan toward and into bin  38 . Alternately, the rails  32  and pan  36  may be disposed in such close relation that the rails  32  may be used as the wipers. Wiper or blade  40  may be a solid or segmented blade and may be made from bristles, plastic, foam or other resilient material that can urge the deposited sand along the surface of pan  36  to a recovery bin. Further wiper  40  may be a plurality of nozzles discharging a air curtain or air brush capable of moving sand. Recovery bin may be a conveyor or feed into a conveyor for automated removal of unwanted sand as is well know in the art. 
         [0020]    With reference to  FIGS. 1 and 3 , note that cars  14  adjacent the pouring station  12  are indexed from left to right, thus cars  14  exiting the pouring station carrying at least one mold  14  with a weight and jacket  20  and solidifying metal there within move one at a time onto the transfer mechanism. As noted above, the cars  14  cannot be indexed unless rail sets  32  are in alignment with the rails supporting the cars being indexed. Due to the spacing of the rail sets, the rails sets on chains  24  will simultaneously align with the rails passing through pouring station and the rails on which the cars  14  move back to the weight and mold shifting station. Thus, cars may be indexed along each set of rails simultaneously. After a car carrying a jacketed mold has been indexed on rail set  32 , chains  24  move the car into alignment with the rail set leading to the mold shifting station  18 , thus leaving the next rail set in position to receive the next car bearing a jacketed mold. Because the chains always move in the same rotational direction an empty rail set is always brought into alignment with the line rails at the discharge end of a line. The same holds true at the weight shifting and jacketing end of the cast line where the weight and jacket are removed from the innermost mold, and all of the molds on the car are shifted outwardly along the length of the car one mold position, such that the mold having the longest dwell time on the car is discharged in a conventional manner. Thus, by indexing the line a car with an empty mold position is moved onto the transfer mechanism adjacent the mold shifting station. Chains  24  then bring the rail set supporting the car into alignment with the rails passing through the pouring station, and an empty rail set into alignment adjacent the mold shifting station. A fresh mold is transferred to the empty mold position and the car awaits indexing back onto the rails passing through the pouring station. 
         [0021]    It is to be understood that what is shown is a preferred embodiment and that various changes and modifications may be made therein without departing from the spirit of the invention or scope as defined in the following claims.