Patent Publication Number: US-8967363-B2

Title: High volume excavating and loading apparatus and method

Description:
FIELD OF THE INVENTION 
     This invention relates to mining machinery and more specifically to an apparatus and method for high volume excavating and loading of ores. 
     BACKGROUND OF THE INVENTION 
     One of the most common arrangements for moving large quantities of heavy material such as overburden from strip mining operations, earth from excavation operations, and other similar material movement, is to use large electric or hydraulic excavators to lift the material into large trucks. Hydraulic excavators come with either front shovel boom arrangements or backhoe booms. 
     Large electric and hydraulic excavators are typically on crawler tracks and have a large volume bucket that is at the end of a boom and is commonly rated by the cubic yards of material that it will hold. The capacity of most large electric shovels is typically in the range of 70 to 80 cubic yards, commonly quoted as 70 to 80 yards. The capacity of hydraulic excavators is typically in the range of 45 to 50 cubic yards. 
     Once the operator moves the shovel to the desired area, the boom is swung toward the pile and the bucket is pushed through the pile until it is full of material. In order to maximize the operating time of the shovel, several trucks are used. Trucks typically line up on either side of the large shovel so that, after a truck on one side is loaded, the shovel operator swings to the opposite side to continue operating. A line of trucks is typically formed on each side of the shovel in order to maximize productivity of the shovel and avoid shutting down the loading operation. Operating in this manner, a large electrical shovel with a 70 yard bucket can typically load about 14,000 tons of earth per hour. 
     Although this production rate is impressive, the efficiency of the shovel is limited by the dead time that occurs with each loading cycle of a truck. A loading cycle includes the time it takes for the operator to drive the bucket through the pile, swing the loaded bucket from the pile while raising it above the truck, then release the load into the truck. The typical cycle time on large shovels is typically around 35 seconds. The truck is therefore sitting idle for much of the time while the operator runs through his loading cycle and this reduces the efficiency of the operation. With the high cost of fuel and the enactment of legislation reducing carbon emissions of trucks, the costs of operating large electric or hydraulic shovels is very expensive. The cost of a large electric shovel is also very expensive, typically in the range of $30 million for a 70 yard shovel. 
     Accordingly, there is a need to reduce the unproductive time and improve the efficiency in moving large quantities of heavy material to a waiting transport vehicle such as a truck. It would also be beneficial to reduce the cost of the equipment for performing this operation. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an excavating and loading apparatus and method. The excavating and loading apparatus includes an excavator and a stacker conveyor. The excavator includes paired crawler tracks and an articulated boom with a bucket. The excavator further includes an inclined feeder conveyor with an intake end and a discharge end. A wide apron is positioned at the intake end of the feeder conveyor. The apron includes a left-hand side and right-hand side load receiving area that are arranged on opposing sides of the intake end of the feeder conveyor. Two double-hinged feeder blades are positioned at the apron. The feeder blades are arranged to operate asynchronously. Each feeder blade includes a main blade and a wing blade. The stacker conveyor is on paired crawler tracks and includes an intake end and a discharge end. The articulated boom pulls material to a first side of the apron in which the feeder blades are open, after which the feeder blades on that side activate and push the material from that side of the apron onto the intake end of the feeder conveyor. The feeder conveyor runs continuously and delivers the loaded material to the stacker conveyor which delivers the material to a waiting truck, similar haulage vehicle, or feeder-breaker to be crushed and fed onto an overland conveyor. The excavating and loading apparatus continues to load in this manner, with the double-hinged feeder blades operating asynchronously, wherein a first side of the apron is loaded by the bucket while the opposing side is deactivated after which the first side feeder blades are deactivated and the second side feeder blades are activated. In this manner, asynchronous operation of the feeder blades continuously delivers material to the feeder conveyor whereupon the feeder conveyor continuously delivers material to the stacker conveyor. 
     OBJECTS AND ADVANTAGES 
     A first object of the invention is to provide an excavating and loading apparatus that is more efficient than conventional large electric or hydraulic shovels in loading trucks or similar vehicles. This is accomplished by reducing the non-productive cycle time that is typical of large conventional shovels. A large shovel typically requires 35 seconds to complete one cycle, which includes pulling the bucket through the muck, swinging the boom to position the bucket over the truck, dumping the bucket contents into the truck, and then swinging the boom and bucket back to the muck. The excavating and loading apparatus of the current invention operates continuously, with the backhoe reaching up and out into the material and pulling it to the apron. The apron is thus continually fed by a bucket and a feeder conveyor and stacker conveyor continuously transport the material to a truck or similar vehicle. 
     A second object is to provide a large volume excavating and loading apparatus that can be produced at a substantially lower cost than conventional electric shovels. A conventional electric shovel typically costs about $30 million. The excavating and loading apparatus of the present invention would cost about half of the cost of a typical electric shovel. 
     A third object is to provide an excavating and loading apparatus that will load at a higher rate than conventional electric shovels. The excavating and loading apparatus of the present invention is capable of loading at a rate of 16,000 tons per hour versus a rate of 14,000 tons per hour for a conventional electric shovel with a 70 cubic yard bucket. 
     A further object is to provide a high volume excavating and loading apparatus that is much smaller than conventional electric shovels. As a result of the continuous conveying of the mined material from the front apron of the excavator to the truck bed, the cycle time is substantially lower than the cycle time of a typical electric shovel. This is a result of eliminating the need to swing the boom from the pile to the truck, dump the bucket contents, and then swing the boom back into the digging position. The boom and bucket are operated constantly in excavating and loading apparatus of the present invention and there is no need to swing the load back to the truck as the double hinged feeder blades operate alternately to push mined material from the apron to the feed conveyor and on to the stacking conveyor to convey the load to the truck or feeder-breaker. 
     These and other objects and advantages of the present invention will be better understood by reading the following description along with reference to the drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the preferred embodiment of an excavating and loading apparatus according to the present invention. 
         FIG. 2  is a side elevation view of the excavating and loading apparatus of  FIG. 1 . 
         FIG. 3  is a top view of the excavating and loading apparatus. 
         FIG. 4  is a top view of the excavating and loading apparatus with the control cabin rotated to load the left side of the apron. 
         FIG. 5  is a side view of the excavating and loading apparatus with the boom and bucket directed downward to dig below grade. 
         FIG. 6  is a front view of the excavating and loading apparatus with the boom and bucket raised. 
         FIG. 7  is a side elevation view of the excavator portion of the excavating and loading apparatus of the present invention. 
         FIG. 8  is a top view of the apron portion of the excavating and loading apparatus depicting the double hinged feeder blades in the open position. 
         FIG. 9  is a top view of the apron area depicting the main blade of the right side double hinged feeder blade in its fully extended position and the wing blade open. 
         FIG. 10  is a top view of the apron area depicting the main blade of the right side double hinged feeder blade in its fully extended position and the wing blade closed. 
         FIG. 11  is a top view of the apron area depicting the main blade of the right side double hinged feeder blade partially during its closing sequence with the main blade retracted from its fully extended position. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1  there is shown the preferred embodiment of an excavating and loading apparatus  20  according to the present invention. The excavating and loading apparatus  20  includes an excavator  22 , a feeder conveyor  24 , and a stacker conveyor  25 . The excavator  22  includes a front end  26 , an upper stage  27  that includes a control station  28 , paired crawler tracks  29 , and an articulated boom  30  with a bucket  32 . The feeder conveyor  24  is pinned beneath the upper stage  27  and includes an intake end  34  and a discharge end  36 . A wide apron  38  is positioned at the intake end  34  of the feeder conveyor  24 . The paired crawler tracks  29  of the excavator are supported by a crawler frame  39 . 
     Referring to  FIG. 2 , the excavator  22  is connected to bucket  32  by articulated boom  30  and stick  40 . The stacker conveyor  25  is on paired crawler tracks  42  and includes an intake end  44 , a discharge end  46 , and side walls  48  for containing material on the stacker conveyor. The paired crawler tracks  42  of the stacker conveyor  25  are supported by a crawler frame  49 . 
     As shown in  FIG. 3 , with boom  30  and stick  40  extended along the axial center of the excavator  22  the bucket  32  extends in front of the apron  32 . The apron  38  includes a left side load receiving area  50   a  and right side load receiving area  50   b  that are each capable of receiving a load of material. The load receiving areas  50   a  and  50   b  are arranged on opposing sides of the intake end  34  of the feeder conveyor  24 . Two double-hinged feeder blades including a left-hand feeder blade  52   a  and a right-hand feeder blade  52   b  are positioned at the rear  54  of the apron  38 . The double hinged feeder blades  52   a  and  52   b  are arranged to operate asynchronously. 
     With reference to  FIG. 4 , the upper stage  27  and articulated boom  30  are capable of being rotated by approximately 30° to each side. With the upper stage  27  rotated 30° to the left as shown and with left-hand feeder blade  52   a  open, or positioned at the rear  54  of the apron  38 , the bucket  32  can be retracted in order to pull material onto the left side load receiving area  50   a . Conversely, with the right-hand feeder blade  52   b  open, the upper stage  27  and articulated boom  30  can be rotated by approximately 30° to the right side in order to pull material onto the right side load receiving area  50   b . As shown in  FIG. 5 , feeder conveyor  24  includes side walls  55  that contain material on the conveyor.  29 ) Referring to  FIG. 6 , the angle of boom  30  can be changed by actuating paired boom cylinders  56 , which are preferably hydraulic cylinders. A slewing bearing  58  connects the upper stage  27  to the lower frame  60  and enables the upper stage  27  and articulated boom  30  to rotate with respect to the lower frame. As shown apron  38  includes a front edge  62  that can be lowered to meet grade level at the excavation site. Double-hinged feeder blades including left-hand blade  52   a  and right-hand blade  52   b  each include a main blade  64  and a wing blade  66 . 
     As shown in  FIG. 7 , articulated boom  30  further includes stick cylinders  68  to change the angle of stick  40  with respect to boom  30 , and bucket cylinders  70  in order to change the angle of the bucket  32  with respect to the stick  40 . Controls for actuating any of the cylinders are located in control station  28 , and can be manipulated by the operator as required to pull material onto the apron  38 . An apron cylinder  72  extends between the front of the lower frame  60  and apron  38  and enables the operator to raise and lower the apron  38  and the intake end  34  of the feeder conveyor  24 . The apron  38  is typically lowered to ground level for loading material onto the apron and is typically raised in preparation for activating excavator crawler tracks  29  for moving the excavator  22  to a new location. The excavator  22  further includes a pin  74  extending between the rear of the lower frame  60  and the feeder conveyor  24 . The pin  74  enables the discharge end  36  of the feeder conveyor  24  to pivot with respect to the lower frame  60 . During loading operations of the excavator  22 , the discharge end  36  of feeder conveyor  24  is pinned higher than the input end  44  of stacker conveyor  25 . Apron  38  includes a nose portion  75  extending downward from its front edge. 
       FIGS. 8-11  are top views of the apron  38  portion of the excavating and loading apparatus depicting the double-hinged feeder blades  52   a  and  52   b  in various positions during a typical loading operation. As shown in  FIG. 8 , initially the left-side hinged feeder blade  52   a  and the right-side hinged feeder blade  52   b  are in the open position, with the feeder blades positioned near the rear  54  of the apron  38 . Left-side feeder blade  52   a  is positioned behind left side load receiving area  50   a  and right-side feeder blade  52   b  is positioned behind right side load receiving area  50   b . Both the left and right side feeder blades include a main blade cylinder  76  connecting at one end to the feeder conveyor framework  78  and at its opposing end to a bracket  80  on the main blade  64 . A wing blade cylinder  82  extends between bracket  80  and bracket  84  on the wing blade  66 . Thus, via activation of main blade cylinder  76  and wing blade cylinder  82 , main blade  64  can pivot around main pin  86  and wing blade  66  can pivot around wing pin  88 . Thus  FIG. 8  depicts the double-hinged feeder blades  52   a  and  52   b  in the open position. 
     With reference to  FIG. 9 , after the excavator has loaded material onto the right side load receiving area  50   b , main blade cylinder  76  is extended to push material from the right side load receiving area  50   b  onto the intake end  34  of the feeder conveyor  24 .  FIG. 9  depicts the main blade  64  closed and wing blade  66  open. 
     Referring to  FIG. 10 , after the main blade  64  is closed, wing blade cylinder  82  is fully extended to fully close the wing blade  66  and thereby further push material from the apron  38  and the nose portion  75  portion of apron  38  onto the intake end  34  of the feeder conveyor  24 . This effectively pushes all material from the right side load receiving area  50   b  onto the feeder conveyor  24 . 
     With reference to  FIG. 11 , after the material on the right side load receiving area  50   b  has been pushed onto the feeder conveyor  24 , main blade cylinder  76  begins to retract and pulls the main blade  64  toward the open position. As main blade  64  is opening, wing blade  66  remains closed until main blade  64  is fully open. Wing blade cylinder  82  is then retracted to fully open the wing blade  66 . After the material on right side load receiving area  50   b  has been forced onto the feeder conveyor  24 , the right side wing blade  66  critically is kept closed while main blade  64  is opening. At the same time right-side hinged feeder blade  52   b  is sequencing from closed to open position, the left side load receiving area  50   a  becomes active and may be reloaded with material from the bucket (not shown). Thus the wing blade  66  is held closed on the feeder blade  52   b  that is in the process of opening in order to keep the load receiving area  50   a  on the opposing side open and ready to accept material. The double hinged feeder blades  52   a  and  52   b  are designed to operate asynchronously. The asynchronous operation is controlled by a microprocessor to ensure that one load receiving side of the apron  38  is open while the opposing load receiving side of the apron is closed. 
     As shown in  FIG. 11 , the feeder conveyor  24  extends a substantial distance into the apron  38 . Thus, as either of the hinged feeder blades  52   a  and  52   b  is closed, material will quickly be transferred from the load receiving area onto the intake end  34  of the feeder conveyor  24 . Operation of the excavating and loading apparatus is continuous as the hinged feeder blades  52   a  and  52   b  continue to open asynchronously and the operator pulls material onto the open side of the apron  38  as needed. 
     With reference to  FIG. 1 , in operation, the articulated boom  30  is extended onto the pile and is retracted to pull material onto a first side  50   a  or  50   b  of the apron  38 . The double-hinged feeder blades  52   a  or  52   b  on the loaded side of the apron are then activated in the sequence described hereinabove to push material onto the feeder conveyor  24 . After the active feeder blade is in its fully closed position, the bucket is used to pull material onto the opposing side of the apron. After the double-hinged feeder blade on the first side is returned to the open position, the double-hinged feeder blade on the opposing side is activated to push the material on that side of the apron  38  onto the feeder conveyor  24 . The double-hinged feeder blades  52   a  and  52   b  continue to operate asynchronously as the operator continues to pull material to the empty side of the apron at the proper time during each cycle. The asynchronous cycling of the double hinged feeder blades  52   a  and  52   b  continues while the articulated boom  30  and bucket  32  are operated to alternatively load the open side of the apron  38 . While the excavator  22  is continues to work to fill the apron  38 , the feeder conveyor  24  and the stacker conveyor  25  run continuously to deliver the excavated material to the truck  90 . 
     As the apron  38  is continually reloaded with material by the excavator  22 , the inclined feeder conveyor  24  runs continuously and conveys material to the rear of the excavator and onto the stacker conveyor  25 . The intake end  34  of the feeder conveyor  24  is positioned in the middle of the apron  38 , thus, as each double hinged feeder blade  52   a  and  52   b  closes, the feeder conveyor  24  is reloaded with material. The stacker conveyor  25  receives material from the discharge end  36  of the feeder conveyor  24  and runs continuously to convey the material to its discharge end  46  whereupon the material falls into a waiting truck  90 , similar haulage vehicle, or feeder-breaker to be crushed. 
     Although the description above contains many specific descriptions, materials, and dimensions, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.