Patent Publication Number: US-3876191-A

Title: Furnace ladling apparatus and crucible

Description:
Apr. 8, 1975 I United States Patent Lauersdorf [54] FURNACE LADUNG APPARATUS AND FOREIGN PATENTS OR APPLICATIONS mmm 00&#34; dd.&#34; 0 .m.m y 43 .mmm nne UUG 057 765 9 99 HHH 2000 994 476 6 5 05 n t m ch r o d S a L H e n. me E Dw M l m C t n W e v C m J 7 .l  
 Assignee: Sola Basic Industries, Inc.,  
  Primary E.\&#39;ammer-Gerald A. Dost Milwaukee Wm Attorney. Agent, or Firm-Smythe &amp; Moore Mar. 15, 1973 [22] Filed:  
 [57] ABSTRACT A furnace ladling apparatus comprises a crucible Appl. No.: 341,736  
 mounted in a furnace and having an inlet passage and delivery tube disposed within the crucible adjacent a side wall thereof. A delivery spout extends from an opening communicating with the delivery tube in the 94 bn33 M 8 6 3 26 a 9 &#39;1 3 &#34;l N N 2 n .9 2 &#34;0 a m B u we 6 n 0 6 U 2 n u 3 &#34;&#34;00 m m m 7 m5 r wk S5 .l f C M d6 Sol fl UmF mum 555 upper end of the crucible. A pair of reference electrodes are spaced along one side of the passage in the 222/399, DlG. l2  
 delivery spout so as to be responsive to the level of molten metal in the spout. Shot timer means are con- [56] References Cited UNITED STATES PATE NTS nected to the reference electrodes so that the timer is actuated when the molten metal reaches the reference electrodes in the delivery spout so as to provide a predetermined amount of metal.  
 &#39;2 Claims, 5 Drawing Figures Tornberg........... Morris et al. Schwartz et a1. 960  
  L e m 6 HL .llrilliil IR PRESSURE 07 @QMQQQEQ VQQQE FURNACE LADLING APPARATUS AND CRUCIBLE The present invention relates to a furnace ladling apparatus and, more particularly, to a crucible for the apparatus having a delivery spout with reference level means therein.  
  A number of different furnace ladling devices have been proposed for forcing molten metal from the chamber of a melting furnace to a desired point of use, such as to a die-casting machine. Such devices have been generally in the form of a crucible which has a discharge tube external to the main body of the crucible and extending upwardly to a point above the molten metal in the chamber and discharging the metal adjacent to one side of the chamber. When used in conjunction with a die-casting machine, measured shots or amounts of molten metal are periodically discharged. Examples of such are seen in US. Pat. Nos. 2,846,740, 3,050,794, 3,191,247 and 3,229,337.  
  When the apparatus is so constructed that the molten metal may stand in the discharge tube above the level of molten metal in the chamber between successive shots, there is a tendency for the metal in the upper part of the discharge tube to freeze or to cool to a mushy consistency should the duration between successive shots become too great. If there are any delays due to difficulty with the die-casting machine or for any other reason, a freezing or partial freezing of the metal in the discharge tube may occur which in turn makes it difficult to restart the operation.  
  One of the objects of the present invention is to provide an improved crucible for a furnace ladling apparatus.  
  Another of the objects of the invention is to provide an improved device for dispensing a predetermined amount of molten metal from the discharge spout.  
  Another object of the invention is to eliminate the necessity of modifying the furnace body for a discharge tube.  
  According to one aspect of the present invention, a furnace ladling apparatus has a hollow chamber to contain molten metal and a crucible is positioned in the chamber. The crucible comprises means for defining a molten metal inlet and it also has a delivery tube with the upper end of the tube terminating above the normal level of molten metal in the chamber. A delivery spout is connected to the delivery tube open end and the spout includes means responsive to the level of molten metal therein. The metal inlet and delivery tube both comprise vertically extending passages which are positioned adjacent the inner face of the wall of the crucible.  
  Other objects, advantages and features of the present invention will become apparent from the accompanying description and drawings, which are merely exemplary.  
 In the drawings:  
  FIG. 1 is a vertical sectional view through a portion of a furnace ladling apparatus and through a crucible mounted within the furnace;  
  FIG. 2 is a top plan view of one form of crucible showing the arrangement of passages therein;  
  FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2;  
  FIG. 4 is a sectional view taken along the line 44 of FIG. 2; and  
  FIG. 5 is a schematic diagram&#39;showing one form of an electrical control circuit including a shot size&#39;timer and reference electrodes actuating the timer.  
  Proceeding next to the drawingswherein like reference symbols indicate the same parts throughout the various views, a specific embodiment of the present in vention will be described in detail.  
  As may be seen in FIG. 1, there is shown a furnace indicated generally at 10 which may be any desired type of metal melting or holding furnace formed of refractory material and defining an inner chamber 11 containing molten metal 12. In operation of the furnace, it is generally contemplated that the level of the metal therein will vary from level 12 to a lower minimum level which will not fall below the bottom end of a crucible 13 mounted within the furnace.  
  The upper end of the crucible is constructed with a flange 14 which rests upon a crucible cradle 15 mounted on the top 16 of the furnace and secured in position by bolt means 17. The crucible is closed by a clean-out lid 18 to which is connected nipple 19. The lid 18 also has an opening 20 to receive the upper end of delivery tube 21 whose lower end is open at 22 and extends below the normal level of the molten metal within the furnace.  
  The crucible 13 can be made of a suitable refractory. One refractory is a clay-free mixture of silicon carbide and zircon which is thixotropically cast in the mold and then fired or sintered. The particle sizes of silicon carbide and zircon are chosen to provide the desired characteristics. In addition, suitable water retention and dispersing agents can be added to the mixture.  
  Also mounted within the crucible is a vertically extending inlet tube 23 (FIG. 4) whose lower or inlet end 24 opens at the bottom of the crucible and whose upper end 25 opens into the crucible space below the top thereof.  
  As can be best seen in FIGS. 2 to 4, both of the delivery and inlet tubes 21 and 23 can be positioned side by side within the crucible against an inner face of the cylindrical wall of the crucible and may be integrally formed with the wall of the crucible, as shown in the drawings. Thus, the inlet tube and delivery tube are integral components of the crucible, and their position within the crucible enables the molten metal within the crucible to prevent excessive heat loss of the metal in these tubes.  
  The upper end of the delivery tube 21 is indicated at 26 and is connected to an opening 27 (FIG. 1) in a delivery spout 28 which has a passage 29 with an upwardly inclined bottom surface 30 extending to a discharge opening 31 below which can be positioned a shot cylinder 32 as is known in the art. The function of the delivery spout 28 is to transfer molten metal from the crucible to the shot well of a die-casting machine (not shown). Positioned on sides of the delivery spout are two spaced reference electrodes 33 and 34. Metal entering the delivery spout through the opening 27 continues to rise until the metal shorts out across both electrodes, thereby acting as a switch to start the timing of the shot size timer, which may be seen in the control circuit of FIG. 5. As soon as the shot is completed, the metal in the delivery spout runs back into the crucible to clear the reference electrodes.  
  Electrode 33, which is closer to the discharge opening 31, is positioned at the horizontal level of this opening so that this electrode will be contacted by the metal at the precisemoment that the metal begins to flow through the opening 31 into the shot cylinder so as to start the timing cycle.,Electrodes 33 and 34 may comprise conventional spark plugs, and the reference level detector may operate at a low voltage, such as 12 volts. As known in the art, nipple l9 communicating with the upper end of the crucible 13 is connected to a suitable compressed air supply which is used to introduce a pressure into the crucible to force the metal through the delivery tube and out through the delivery spout. It also is possible to alternately connect a vacuum to the crucible.  
  The size of the shot in the die-casting machine is determined by the setting of the shot size timer and the pump flow rate valve. Once the proper flow rate is established, the size of the shot can be changed by varying the setting of the shot size timer. Once the timer has been set to the desired time, the furnace will continue to deliver an identical amount of metal with each shot.  
  Referring now to one form of circuit which can be used, such as seen in FIG. 5, line voltage is applied at 35 to the circuit. The operation can be started by closing start switch 36 which will energize the primary of step-down transformer 37. When the start switch 36 is actuated, relay 38 will be closed which is a lock-in arrangement andwill close contacts 39. In case there is a power failure, the circuit will open. The shot size 1 timer, which can be a conventional timer means, is indicated as being within the dot-dashed lines 44. Switch 45 is an interlocking circuit which indicates that the shot well is cleared so as not to pump one batch of metal upon another. When switch 46, which is a limit switch on the die-casting machine, closes, the relay 41 will be activated so that the pumping action then is actually started. Relay 42 is a backup timer. As metal comes into passage 29, it will close the circuit across the electrodes 33 and 34 which will result in the secondary of transformer 37 energizing relay 47. When relay 47 is energized, contacts 48 will close to energize the shot size timer 44. When the shot size timer times out, it operates to open switch 49.  
  The proper timer setting can be determined for each size shot in accordance with procedures well known in the art.  
  In the form shown in FIG. 1, the height of top 25 is so related to the level of the metal that flow into the crucible will be by gravity. If the height of the top end 25 is above the normal level of molten metal in the furnace 10, then a vacuum can be applied to the chamber 50 through opening 19.  
  Thus, it can be seen that the present invention provides for the automatic energization of the shot size timer in response to a predetermined level of liquid in the delivery spout. The level of liquid may coincide with the initial flow of liquid through the delivery spout so that the timer will be energized at the beginning of the flow of metal for a shot. In addition, there is disclosed a crucible where the inlet and delivery tubes are disposed completely within the outline of the crucible whereby freezing of metal which may be in the tubes is,  
 largely eliminated.  
  It will be understood that changes in various details of construction and arrangement of parts may be made without departing from the spirit of the invention except as defined in the appended claims.  
 What is claimed is:  
  1. In a furnace ladling apparatus, the combination including a hollow chamber to contain molten metal, a crucible in said chamber, means in said crucible and integral therewith defining a molten metal inlet therein, a delivery tube within said crucible and integral therewith having its upper end terminating above the normal level of molten metal in the chamber, a delivery spout in fixed position on said crucible and communicating with the delivery tube upper end, and means in said delivery spout responsive to the level of molten metal therein, said metal inlet and delivery tubes comprising means defining vertically extending passages within the crucible, the vertical passages being positioned adjacent each other and to the inner face of the side wall of said crucible.  
  2. A crucible for a furnace ladling apparatus comprising a substantially cylindrical body having top and bottom ends adapted to be placed in a metal holding furnace, means in said crucible defining a first integral vertically extending passage opening at the bottom of the crucible for a molten metal inlet, means in said crucible defining a second integral vertically extending passage having its upper end terminating above the normal level of molten metal within the furnace for the delivery of molten metal from the crucible, said passage defining means being against the inner face of the crucible body wall, and said inlet passage and said delivery tube are positioned adjacent each other against the inner face of the cylindrical wall of the crucible.