Abstract:
An aluminum furnace charging system including a movable charger assembly, a hydraulically operated ram assembly, a hydraulically operated elevator and aluminum furnace having a hydraulically operated door whereby aluminum billets and/or scrap aluminum loaded onto the elevator is automatically and quickly charged to the furnace so that heat loss from the furnace and escape of molten aluminum from within the furnace is minimized.

Description:
FIELD OF THE INVENTION 
     This invention relates to an improved system for charging aluminum billets and other aluminum articles such as scrap aluminum to an aluminum furnace. 
     BACKGROUND OF THE INVENTION 
     Systems for loading aluminum to aluminum furnaces are well known. Typical aluminum furnace loading systems use a forklift to lift heavy, and sometimes unstable loads of aluminum billets or scrap aluminum to the height of the furnace door and then to deposit the aluminum into the interior of the furnace. This conventional method is undesirable, especially when the loads are unstable. Also, due to the potential of molten aluminum escape from the inside of the furnace when the forklift operator or others are in close proximity to the open furnace door, the conventional method of charging aluminum to the furnace is additionally undesirable. Furthermore, during conventional charging, the furnace door remains open a relatively long time and sufficient heat may be lost through the open door of the furnace to cause cold spots in the molten aluminum within the furnace. 
     OBJECTS OF THE INVENTION 
     It is an object of the present invention to provide an improved aluminum furnace charging system. 
     It is further object of the present invention to provide a remote controlled aluminum furnace charging system. 
     It is a further object of the present invention to provide an aluminum furnace charging system in which heat loss from and formation of cold spots within the furnace is minimized during charging operations. 
     It is a further object of the present invention to provide an aluminum furnace charging system which provides for safe lifting and loading of heavy materials into an aluminum furnace. 
     It is a further object of the present invention to provide a hydraulically operated ram type charger for loading an aluminum furnace. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a perspective view of an aluminum furnace charging system of the present invention shown in pre-charging mode. 
     FIG. 2 is a perspective view of the FIG. 1 charging system shown in a charging mode. 
     FIG. 3 is a perspective view showing details of the ram assembly of the FIG. 1 system. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to FIGS. 1-3, the preferred embodiment of the present invention and its operation will be described. 
     Referring to FIGS. 1 and 2 the charger assembly 10, furnace 12 and elevator 14 are shown. Charger assembly 10 includes a flat surface, or table 16 upon which ram assembly 18 is positioned within framing members 20, 22, 23, 24 and 25. The ram assembly 18 is positioned on lower rollers 26a and b, 28a and b, 30a and b, 31a and b and under upper rollers 32a and b, 34a and b, 35a and b, 36a and b, and side rollers 37a and b, 38a (not shown, but attached to framing member 22 in line with side rollers 37a and 39a and immediately opposite 38b) and b and 39a and b to provide for forward (toward furnace 12) and backward movement across the surface 16. The ram assembly 18 also includes hydraulic cylinder 40, piston 41 and front plate 42, the operation of which will be described hereinafter with reference to FIG. 2 and FIG. 3. Hydraulic cylinder 40 is fixed to the top of table 16 with a bracket 44 by conventional means, such as by welding or by bolting. Hydraulic cylinder 40 is shown with charge lines 46 and retraction lines 48 at opposite end, to permit circulation of hydraulic fluid for charging and retracting the piston 41 in a conventional manner. It should be noted that because of the heat emitted from furnace 12, a water soluble, nonflammable hydraulic fluid is preferably used to reduce the hazard of fire or explosion. 
     The charger assembly table 16 rests on four legs, not numbered, which are mounted on rollers to permit movement of the charger assembly 10 along tracks 50 and 52. Four of the wheel assemblies are shown at 54, 46, 58 and 60 respectively. The charger assembly also is provided with a lower surface or table 62 upon which a conventional power unit 64 and a control panel 66 are positioned. A conventional microprocessor controller, such as, for example, a programmable controller manufactured by Allen-Bradley, a Rockwell International Company, of Milwaukee, (Model No. 1745-LP151), not shown, is used to control operation of the charger assembly. 
     Aluminum furnace 12 is shown as a generally rectangular furnace having a furnace door 68 with cable 70 and pin bracket 72. Back stop 74 is positioned against the wall of the furnace. Door 68 covers the furnace entrance into which aluminum billets and/or scrap aluminum is charged. 
     Again referring to FIG. 1, elevator 14 is shown having a flat surface 78 upon which two aluminum billets 80 and 82 are positioned. Although elevator 14 is shown as having two aluminum billets, the number, weight and size of the billets may vary and other aluminum materials such as aluminum scrap may be placed on the elevator surface 78 in any conventional manner. It is preferred that the material to be charged be placed in abutment against the back stop 74. 
     Elevator 14 also includes a conventional elevating, or jacking system, shown in the retracted, or down position in FIG. 1 so that the surface 78 is close to the ground. Elevator 14 is also positioned on four legs, each of which has wheel assemblies like those of the charger assembly, to provide for movement of the elevator along tracks 84 and 88. However, in this preferred embodiment, elevator 14 is fixed in position with conventional means, such as by pinning or bolting, in front of furnace 12. 
     Referring to FIG. 2, the charger assembly of the present invention is shown with the ram assembly 18 in the charge position, that is, with the piston 41 and plate 42 in the fully extended position and furnace door 68 fully opened. Also referring to FIG. 2, the elevator 14 is shown in the extended, raised position. 
     Referring to FIG. 3 the ram assembly is shown having rectangular plate 42 to which is attached on its left and right sides and its top side rectangular members which extend forwardly and collectively define a hood 94. Fixed to the back side of plate 42 is piston 41 and at each distal edge of plate 42 long, rectangular, rearwardly extending beams 90 and 92 are attached by conventional means, such as be welding or bolting. Upper rails 96 and 98 are fixed to the top sides of beams 90 and 92, respectively, also by conventional means of attachment such as welding or bolting. In a like fashion, lower rails (not shown) are fixed to the bottom sides of beams 90 and 92. Also, side rails are similarly fixed lengthwise to the outer sides of beams 90 and 92. Side rail 99 is shown fixed to beam 92. The corresponding side rail fixed lengthwise to the outer side of beam 90 is not shown. The upper rollers 32a, 34a, 35a and 36a roll on upper rail 96. The upper rollers 32b, 34b, 35b and 36 b roll on upper rail 98. The lower rollers 26a, 28a, 30a, 31a roll on the lower rail fixed to the bottom side of plate 90, while the lower rollers 26b, 28b, 301, 31a roll on the lower rail fixed to the bottom side of plate 92. The side rollers 37a, 38a and 39a roll on the side rail fixed to the outer side of beam 90, and the side rollers 37b, 38b and 39b roll on side rail 99. All said rollers have a substantially V-shaped groove formed within the outer rolling surface thereof and all said rails are substantially V-shaped with the point of the V extending away from the side of the beam to which the rail is attached. Thus, when the rollers roll on the rails, the V-shaped rails fit within the V-shaped grooves of the rollers and non-linear movement of the ram assembly 18 is thereby restricted. The back of plate 42 is attached to the piston 41 by means of mounting plate 43 as shown in FIG. 1. Piston 41 is operatively connected in a conventional fashion to hydraulic cylinder 40 of the ram assembly 18. Charging lines 46 and retracting lines 48 are also shown as providing for hydraulic fluid entry to and exit from the cylinder 38. The cylinder 40 is rigidly attached to the table surface 16 through bracket 44. 
     With further reference to FIGS. 1-3, the sequence of operation for the charger of the present invention will be described. 
     First, a quantity, typically two billets, and typically weighing about twelve hundred (1200) pounds each and/or scrap aluminum is loaded onto the surface 78 of elevator 14. Typically the aluminum billets or scrap aluminum are placed onto the elevator 14 with a forklift and the aluminum billets or scrap aluminum are positioned to rest up against backstop 74, as shown in FIG. 1. 
     Upon manual initiation at control panel 66, or in accordance with a predetermined time sequence set up through control panel 66 and with the conventional microprocessor unit, not shown, the charger assembly 10 is moved laterally on tracks 50 and 52 to a pre-determined position directly in front of furnace 12 and opposite the loaded elevator 14. When the pre-determined position is reached, pins are automatically moved into position to secure the charger assembly 10 to the furnace 12. The pins are received by holes formed in the charger assembly. One of the pins is shown at 73 and one of the holes is shown at 75 for illustration purposes. In the preferred embodiment, two pins are used. Adjacent to pin 73 is a limit switch which is activated by the charger assembly which stops movement of the charger assembly along the tracks 50 and 52. 
     After the charging unit 10 is secured to the furnace in the proper position, the charging operation is started either manually or in accordance with a predetermined, timed program. Upon activation of the charging operation, the elevator 14 and furnace door 68 lift simultaneously. Movement of the furnace door 68 and elevator 14 are stopped through operation of appropriately placed limit switches, not shown. 
     In the preferred embodiment, the control circuitry is st up such that if the elevator 14 or door 68 do not reach their corresponding limit switches within a pre-determined time, the charging operation will automatically be stopped by the control system and an audible warning will sound. Also, the microprocessor control will cause the ram assembly 18 to automatically retract to the position shown in FIG. 1. 
     When the elevator 14 and the door 68 are at the proper, limited position, the ram assembly 18 is activated so that hydraulic fluid is charged to cylinder 40 through lines 46 to cause plate 42, hood 94 and side plates 90 and 92 to move forward, that is, toward the entrance of the furnace. In the preferred embodiment, activation of the ram assembly is automatically begun upon proper engagement of the limit switches on the elevator 14 and the door 68 when they each reach their pre-determined, extended and open, respectively, positions. Alternatively, the ram assembly may be activated through manual controls at control panel 66. 
     Upon activation of the ram assembly 18, the ram moves forward, that is, toward the open furnace until another limit switch, not shown, is activated. In the preferred embodiment, if the plate 42 does not reach the limit switch within a pre-determined time, the charging operation will stop, an audible warning will sound and the ram will automatically be retracted through operation of the microprocessor control system. 
     Immediately after activation of the limit switch upon the ram reaching a pre-determined, proper position, hydraulic fluid is fed to the cylinder 40 through retraction lines 48 and the ram retracts. Also, through programming of the microprocessor control system, the elevator will begin to descend at this time. When the ram plate 42 is fully retracted, furnace door 68 descends to its normal, closed position. Furnace door 68 is opened and shut through a conventional, hydraulic system which is controlled either automatically or manually through control panel 66. The charger assembly 10 then automatically moves away from the furnace along tracks 50 and 52 to its FIG. 1 position and to expose the top surface 78 of the elevator, for reloading, as appropriate. 
     This sequence is then repeated as many times as desired. The process sequence can be entirely automatic, or can be controlled entirely or partially, by an operator through appropriate controls at control panel 66, which is of conventional design. In a preferred sequence, the entire operation, except for loading the elevator 14, is automatic and is programmed to repeat at fifteen minute intervals. 
     An alternate preferred embodiment charger assembly is envisioned where the charger assembly frame is mounted directly to the furnace, such as by bolts, and is not moved along tracks during normal operation. In this alternative embodiment, only the elevator 14 is moved laterally along its tracks 84 and 88. After charging is complete the elevator 14 would be moved along its tracks and reloaded with aluminum billets, scrap aluminum, et cetera. 
     In either the preferred embodiment or the alternate preferred embodiment, the charger assembly unit and elevator 14 may be moved from the furnace for maintenance and cleaning. The framing 20, 22, 23, 24, 25 and roller 26a and b, 28a and b, 30a and b, 32a and b, 34a and b, 35a and b and 36a and b, 37a and b, 38a and b, and 39a and b associated with the ram assembly function to keep the ram assembly in place, to permit movement of the plate 42 toward and away from the furnace and to prevent tipping of the charger assembly unit during operation. 
     During operation of the conventional aluminum furnace charging systems, the forklift operator, and other workers in close proximity to the furnace door are often at risk to personal injury due to heat and possible molten aluminum being ejected out of the furnace. With the present invention, not only need there be no forklift operator close to the furnace door, but also the charger assembly, in particular the ram assembly plate 42, hood 94, and side plates 90 and 92 provide an effective shield to reflect heat back into and to retain molten aluminum within the furnace. 
     Also, when a conventional furnace, such as furnace 12, is being loaded by a conventional method using a forklift, the furnace door 68 must remain open much longer than with the present system. Thus, in conventional charging of an aluminum furnace sufficient heat is lost from the furnace when the door is opened that cold spots have been known to have been formed inside of the furnace. A conventional aluminum furnace, such as furnace 12, typically operates at temperatures of approximately 2300° F. When using conventional, forklift type charging technology, it is known that this operating temperature will typically drop approximately 600°-700° F. during the loading operation. However, when using the charging system of the present invention, it has been discovered that the temperature drop during the loading operation is limited to approximately 300° F. Reduction in this temperature loss during loading is due to the much faster charging times associated with the charger of the present invention and also due to the fact that the front plate 42 and hood 94 of the ram assembly reflect heat back into the furnace to thus additionally minimize the temperature drop associated with the loading process. 
     Although the preferred embodiment is directed to an aluminum furnace and loading of aluminum material into the furnace, the present invention may be applied to other types of furnaces. Also, manufacture of numerous alternate embodiments of the present invention is well within the ability of one of ordinary skill in the art, and the present invention is not limited to the above described preferred embodiments, but rather is limited by the appended claims and their equivalents.