TRANSFERRING MOLTEN METAL FROM ONE STRUCTURE TO ANOTHER

Abstract

A system and method for transferring molten metal from a vessel and into one or more of a ladle, ingot mold, launder, feed die cast machine or other structure is disclosed. The system includes at least a vessel for containing molten metal, an overflow (or dividing) wall, and a device or structure, such as a molten metal pump, for generating a stream of molten metal. The dividing wall divides the vessel into a first chamber and a second chamber, wherein part of the second chamber has a height H2. The device for generating a stream of molten metal, which is preferably a molten metal pump, is preferably positioned in the first chamber. When the device operates, it generates a stream of molten metal from the first chamber and into the second chamber. When the level of molten metal in the second chamber exceeds H2, molten metal flows out of the vessel and into another structure, such as into one or more ladles and/or one or more launders.

Claims

1. A system for transferring molten metal from a vessel, the vessel comprising at least a first chamber and a second chamber, the first chamber and second chamber being separated by a dividing wall including an opening, the system further comprising: a pump configured to fit into the first chamber and to pump molten metal from the first chamber through the opening in the dividing wall and into the second chamber to raise the level of molten metal in the second chamber to a level at which molten metal flows out of the second chamber; and a degasser in one or both of the first chamber and second chamber, wherein the degasser is configured to degas molten metal.

2. The system of claim 1 that further includes one or more of a launder, a ladle, an ingot mold and a feed die cast machine, wherein when the molten metal flows out of the second chamber it flows into one or more of a launder, a ladle, an ingot mold, and a feed die cast machine.

3. The system of claim 1 wherein the pump is a circulation pump.

4. The system of claim 1 wherein the pump is a gas-release pump.

5. The system of claim 1 wherein the pump is configured to automatically operate when the molten metal within one of a launder, a ladle, and an ingot mold reaches a first level.

6. The system of claim 1 wherein the pump is configured so that its pumping speed varies automatically depending on the amount of molten metal in one of a launder, a ladle, and an ingot mold.

7. The system of claim 1 wherein the pump is configured to automatically operate when the molten metal in the second chamber reaches a second level.

8. The system of claim 1 wherein the pump is configured so that its pumping speed varies automatically depending on the amount of molten metal in the second chamber.

9. The system of claim 1 wherein the pump is configured to automatically stop pumping when the molten metal in the second chamber is at a third level.

10. The system of claim 1 wherein the pump is configured to automatically stop pumping when molten metal in the launder is at a fourth level.

11. The system of claim 1 wherein at least part of the dividing wall has a height of H1 and the second chamber has a wall with an outlet through which molten metal flows out of the second chamber, and the outlet has a height of H2, wherein H1 is greater than H2.

12. The system of claim 11 wherein the entire dividing wall has a height of H1.

13. The system of claim 11 wherein the opening in the dividing wall is in a lower half of the dividing wall.

14. The system of claim 11 wherein the opening in the dividing wall is positioned below H1.

15. The system of claim 1 wherein each degasser is a rotary degasser.

16. The system of claim 1 wherein the opening does not include a filter.

17. The system of claim 1 wherein the pump has a housing with a pump outlet through which molten metal exits, and the pump is positioned in the first chamber so the pump outlet aligns with the opening in the dividing wall in order to pump molten metal from the first chamber through the pump outlet, through the opening, and into the second chamber.

18. The system of claim 17 wherein the pump housing is in contact with the dividing wall.

19. The system of claim 17 wherein the pump housing is in contact with the dividing wall.

20. The system of claim 17 wherein the pump is mounted on the dividing wall.

21. The system of claim 1 wherein the pump is configured to be mounted on the dividing wall.

22. The system of claim 17 wherein the pump is configured to be mounted on the dividing wall and the pump has a height selected so the pump outlet aligns with the opening when the pump is mounted on the dividing wall.

23. The system of claim 1 wherein there is a degasser in only the second chamber.

24. The system of claim 1 wherein there is a degasser in only the first chamber.

25. The system of claim 1 wherein there is a degasser in the first chamber and the second chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 is a cross-sectional side view of a system according to the invention for pumping molten metal from a vessel into another structure.

[0030] FIG. 2 is the system of FIG. 1 showing the level of molten metal in the furnace being increased.

[0031] FIG. 2A shows the system of FIGS. 1 and 2 and displays how heights H1 and H2 are determined.

[0032] FIG. 3 is a top view of the system of FIG. 1.

[0033] FIG. 3A is a partial, cross-sectional side view of a system.

[0034] FIG. 4 is a partial, cross-sectional side view of a system according to the invention that is utilized to fill a ladle.

[0035] FIG. 5 is a cross-sectional side view of a system according to the invention that includes an optional rotary degasser and that feeds two launders, each of which in turn fills a structure such as a ladle or ingot mold.

[0036] FIG. 6 is a partial top view of the system of FIG. 5, showing a scale used to weigh the ladles.

[0037] FIG. 7 is a partial view of a system according to the invention showing a pump in a vessel that is in communication with a launder.

[0038] FIG. 8 is a view of the system of FIG. 7 as seen from side A.

[0039] FIG. 9 is a partial, cross-sectional side view of an alternate embodiment of the present invention.

[0040] FIG. 10 is a cross-sectional side view of a system according to the invention of FIG. 9.

[0041] FIG. 11 is schematic representation of a system according to the invention illustrating how a laser could be used to detect the level of molten metal in a vessel.

[0042] FIG. 12 shows the system of FIG. 11 and represents different levels of molten metal in the vessel.

[0043] FIG. 13 shows the system of FIG. 11 in which the level of molten metal has decreased to a minimum level.

[0044] FIG. 14 shows a remote control panel that may be used to control a pump used in a system according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0045] Turning now to the Figures, where the purpose is to describe preferred embodiments of the invention and not to limit same, FIGS. 1-3A show a system 10 for transferring molten metal M into a ladle or a launder 20. System 10 includes a furnace 1 that can retain molten metal M, which includes a holding furnace 1A, a vessel 12, a launder 20, and a pump 22. However, system 10 need only have a vessel 12, a dividing wall 14 to separate vessel 12 into at least a first chamber 16 and a second chamber 18, and a device or structure, which may be pump 22, for generating a stream of molten metal from first chamber 16 into second chamber 18.

[0046] Using heating elements (not shown in the figures), furnace 1 is raised to a temperature sufficient to maintain the metal therein (usually aluminum or zinc) in a molten state. The level of molten metal M in holding furnace 1A and in at least part of vessel 12 changes as metal is added or removed to furnace 1A, as can be seen in FIG. 2.

[0047] For explanation, although not important to the invention, furnace 1 includes a furnace wall 2 having an archway 3. Archway 3 allows molten metal M to flow into vessel 12 from holding furnace 1A. In this embodiment, furnace 1A and vessel 12 are in fluid communication, so when the level of molten metal in furnace 1A rises, the level also rises in at least part of vessel 12. It most preferably rises and falls in first chamber 16, described below, as the level of molten metal rises or falls in furnace 1A. This can be seen in FIG. 2.

[0048] Dividing wall 14 separates vessel 12 into at least two chambers, a pump well (or first chamber) 16 and a skim well (or second chamber) 18, and any suitable structure for this purpose may be used as dividing wall 14. As shown in this embodiment, dividing wall 14 has an opening 14A and an optional overflow spillway 14B (best seen in FIG. 3), which is a notch or cut out in the upper edge of dividing wall 14. Overflow spillway 14B is any structure suitable to allow molten metal to flow from second chamber 18, past dividing wall 14, and into first chamber 16 and, if used, overflow spillway 14B may be positioned at any suitable location on wall 14. The purpose of optional overflow spillway 14B is to prevent molten metal from overflowing the second chamber 18, or a launder in communication with second chamber 18 (if a launder is used with the invention), by allowing molten metal in second chamber 18 to flow back into first chamber 16. Optional overflow spillway 14B would not be utilized during normal operation of system 10 and is to be used as a safeguard if the level of molten metal in second chamber 18 improperly rises to too high a level.

[0049] At least part of dividing wall 14 has a height H1 (best seen in FIG. 2A), which is the height at which, if exceeded by molten metal in second chamber 18, molten metal flows past the portion of dividing wall 14 at height H1 and back into first chamber 16. In the embodiment shown in FIGS. 1-3A, overflow spillway 14B has a height H1 and the rest of dividing wall 14 has a height greater than H1. Alternatively, dividing wall 14 may not have an overflow spillway, in which case all of dividing wall 14 could have a height H1, or dividing wall 14 may have an opening with a lower edge positioned at height H1, in which case molten metal could flow through the opening if the level of molten metal in second chamber 18 exceeded H1. H1 should exceed the highest level of molten metal in first chamber 16 during normal operation.

[0050] Second chamber 18 has a portion 18A, which has a height H2, wherein H2 is less than H1 (as can be best seen in FIG. 2A) so during normal operation molten metal pumped into second chamber 18 flows past wall 18A and out of second chamber 18 rather than flowing back over dividing wall 14 and into first chamber 16.

[0051] Dividing wall 14 may also have an opening 14A that is located at a depth such that opening 14A is submerged within the molten metal during normal usage, and opening 14A is preferably near or at the bottom of dividing wall 14. Opening 14A preferably has an area of between 6 in..sup.2 and 24 in..sup.2, but could be any suitable size. Further, dividing wall 14 need not have an opening if a transfer pump were used to transfer molten metal from first chamber 16, over the top of wall 14, and into second chamber 18 as described below.

[0052] Dividing wall 14 may also include more than one opening between first chamber 16 and second chamber 18 and opening 14A (or the more than one opening) could be positioned at any suitable location(s) in dividing wall 14 and be of any size(s) or shape(s) to enable molten metal to pass from first chamber 16 into second chamber 18.

[0053] Optional launder 20 (or any launder according to the invention) is any structure or device for transferring molten metal from vessel 12 to one or more structures, such as one or more ladles, molds (such as ingot molds) or other structures in which the molten metal is ultimately cast into a usable form, such as an ingot. Launder 20 may be either an open or enclosed channel, trough or conduit and may be of any suitable dimension or length, such as one to four feet long, or as much as 100 feet long or longer. Launder 20 may be completely horizontal or may slope gently upward or downward. Launder 20 may have one or more taps (not shown), i.e., small openings stopped by removable plugs. Each tap, when unstopped, allows molten metal to flow through the tap into a ladle, ingot mold, or other structure. Launder 20 may additionally or alternatively be serviced by robots or cast machines capable of removing molten metal M from launder 20.

[0054] Launder 20 has a first end 20A juxtaposed second chamber 18 and a second end 20B that is opposite first end 20A. An optional stop may be included in a launder according to the invention. The stop, if used, is preferably juxtaposed the second end of the launder. Such an arrangement is shown in FIG. 5 with respect to launder 20 and stop 20C and 200 and stop 200C. With regard to stop 200C, it can be opened to allow molten metal to flow past end 200B, or closed to prevent molten metal from flowing past end 200B. Stop 200C (or any stop according to the invention) preferably has a height H3 greater than height H1 so that if launder 20 becomes too filled with molten metal, the molten metal would spill back over dividing wall 14A (over spillway 14B, if used) rather than overflow launder 200. Stop 20C is structured and functions in the same manner as stop 200C.

[0055] Molten metal pump 22 may be any device or structure capable of pumping or otherwise conveying molten metal, and may be a transfer, circulation or gas-release pump. Pump 22 is preferably a circulation pump (most preferred) or gas-release pump that generates a flow of molten metal from first chamber 16 to second chamber 18 through opening 14A. Pump 22 generally includes a motor 24 surrounded by a cooling shroud 26, a superstructure 28, support posts 30 and a base 32. Some pumps that may be used with the invention are shown in U.S. Pat. Nos. 5,203,681, 6,123,523 and 6,354,964 to Cooper, and pending U.S. application Ser. No. 10/773,101 to Cooper. Molten metal pump 22 can be a constant speed pump, but is most preferably a variable speed pump. Its speed can be varied depending on the amount of molten metal in a structure such as a ladle or launder, as discussed below.

[0056] Utilizing system 10, as pump 22 pumps molten metal from first chamber 16 into second chamber 18, the level of molten metal in chamber 18 rises. When a pump with a discharge submerged in the molten metal bath, such as circulation pump or gas-release pump is utilized, there is essentially no turbulence or splashing during this process, which reduces the formation of dross and reduces safety hazards. Further, the afore-mentioned problems with transfer pumps are eliminated. The flow of molten metal is smooth and generally at a slower flow rate than molten metal flowing through a metal transfer pump or associated piping, or than molten metal exiting a tap-out hole.

[0057] When the level of molten metal M in second chamber 18 exceeds H2, the molten metal moves out of second chamber 18 and into one or more other structures, such as one or more ladles, one or more launders and/or one or more ingot molds.

[0058] FIG. 4 shows an alternate system 10 that is in all respects the same as system 10 except that it has a shorter, downward, sloping launder 20, a wall 18A′ past which molten metal moves when it exits second chamber 18 and it fills a ladle 52.

[0059] FIG. 5 shows an alternate system 10 that is in all respects the same as system 10 except that it includes an optional rotary degasser 110 in second chamber 18, and feeds either one of the two launders shown, i.e., launder 20 (previously described) and launder 200 (previously described), or feeds both launders simultaneously. If only one launder is fed a dam will typically be positioned to block flow into the other launder. Launder 20 feeds ladles 52, which are shown as being positioned on or formed as part of a continuous belt. Launder 200 feeds ingot molds 56, which are shown as being positioned on or formed as part of a continuous belt. However, launder 20 and launder 200 could feed molten metal, respectively, to any structure or structures.

[0060] A system according to the invention could also include one or more pumps in addition to pump 22, in which case the additional pump(s) may circulate molten metal within first chamber 16 and/or second chamber 18, or from chamber 16 to chamber 18, and/or may release gas into the molten metal first in first chamber 16 or second chamber 18. For example, first chamber 16 could include pump 22 and a second pump, such as a circulation pump or gas-release pump, to circulate and/or release gas into molten metal M.

[0061] If pump 22 is a circulation pump or gas-release pump, it is at least partially received in opening 14A in order to at least partially block opening 14A in order to maintain a relatively stable level of molten metal in second chamber 18 during normal operation and to allow the level in second chamber 18 to rise independently of the level in first chamber 16. Utilizing this system the movement of molten metal from one chamber to another and from the second chamber into a launder does not involve raising molten metal above the molten metal surface. As previously mentioned this alleviates problems with blockage forming (because of the molten metal cooling and solidifying), and with turbulence and splashing, which can cause dross formation and safety problems. As shown, part of base 32 (preferably the discharge portion of the base) is received in opening 14A. Further, pump 22 may communicate with another structure, such as a metal-transfer conduit, that leads to and is received partially or fully in opening 14A. Although it is preferred that the pump base, or communicating structure such as a metal-transfer conduit, be received in opening 14A, all that is necessary for the invention to function is that the operation of the pump increases and maintains the level of molten metal in second chamber 18 so that the molten metal ultimately moves out of chamber 18 and into another structure. For example, the base of pump 22 may be positioned so that its discharge is not received in opening 14A, but is close enough to opening 14A that the operation of the pump raises the level of molten metal in second chamber 18 independent of the level in chamber 16 and causes molten metal to move out of second chamber 18 and into another structure. A sealant, such as cement (which is known to those skilled in the art), may be used to seal base 32 into opening 14A, although it is preferred that a sealant not be used.

[0062] A system according to the invention could also be operated with a transfer pump, although a pump with a submerged discharge, such as a circulation pump or gas-release pump, is preferred since either would be less likely to create turbulence and dross in second chamber 18, and neither raises the molten metal above the surface of the molten metal bath nor has the other drawbacks associated with transfer pumps that have previously been described. If a transfer pump were used to move molten metal from first chamber 16, over dividing wall 14, and into second chamber 18, there would be no need for opening 14A in dividing wall 14, although an opening could still be provided and used in conjunction with an additional circulation or gas-release pump. As previously described, regardless of what type of pump is used to move molten metal from first chamber 16 to second chamber 18, molten metal would ultimately move out of chamber 18 and into a structure, such as ladle 52 or launder 20, when the level of molten metal in second chamber 18 exceeds H2.

[0063] Pump 22 is preferably a variable speed pump and its speed is increased or decreased according to the amount of molten metal in a structure, such as second chamber 18, ladle 52 and/or 52 or launder 20 and/or 200. For example, if molten metal is being added to a ladle 52 (FIG. 4) or 52 (FIG. 5), the amount of molten metal in the ladle can be measured utilizing a float in the ladle, a scale that measures the combined weight of the ladle and the molten metal inside the ladle or a laser to measure the surface level of molten metal in a launder. When the amount of molten metal in the ladle is relatively low, pump 22 can be manually or automatically adjusted to operate at a relatively fast speed to raise the level of molten metal in second chamber 18 and cause molten metal to flow quickly out of second chamber 18 and ultimately into the structure (such as a ladle) to be filled. When the amount of molten metal in the structure (such as a ladle) reaches a certain amount, that is detected and pump 22 is automatically or manually slowed and eventually stopped to prevent overflow of the structure.

[0064] Once pump 22 is turned off, the respective levels of molten metal level in chambers 16 and 18 essentially equalize. Alternatively, the speed of pump 22 could be reduced to a relatively low speed to keep the level of molten metal in second chamber 18 relatively constant but not exceed height H2. To fill another ladle, pump 22 is simply turned on again and operated as described above. In this manner ladles, or other structures, can be filled efficiently with less turbulence, less potential for dross formation and lags wherein there is too little molten metal in the system, and fewer or none of the other problems associated with known systems that utilize a transfer pump or pipe.

[0065] Another advantage of a system according to the invention is that a single pump could simultaneously feed molten metal to multiple (i.e., a plurality) of structures, or alternatively be configured to feed one of a plurality of structures depending upon the placement of one or more dams to block the flow of molten metal into one or more structures. For example, system 10 or any system described herein could fill multiple ladles, launders and/or ingot molds, or a dam(s) could be positioned so that system 10 fills just one or less than all of these structures. The system shown in FIGS. 5-6 includes a single pump 22 that causes molten metal to move from first chamber 16 into second chamber 18, where it finally passes out of second chamber 18 and into either one of two launders 20 and 200 if a dam is used, or into both launders simultaneously, or into a single launder that splits into multiple branches. As shown, one launder 20 fills ladles 52′ while there is a dam blocking the flow of molten metal into launder 200, which would be used to fill ingot molds 56. Alternatively, a launder could be used to fill a feed die cast machine or any other structure.

[0066] FIGS. 9 and 10 show an alternate system according to the invention that includes a relatively small circulation pump used to keep the temperature of the molten metal within the vessel substantially homogenous.

[0067] FIGS. 11-13 show an alternative system 100 in accordance with the invention, which is in all aspects the same as system 10 except that system 100 includes a control system (not shown) and device 58 to detect the amount of molten metal M within a structure such as a ladle or launder, each of which could function with any system according to the invention. The control system may or may not be used with a system according to the invention and can vary the speed of, and/or turn off and on, molten metal pump 22 in accordance with a parameter of molten metal M within a structure (such a structure could be a ladle, launder, first chamber 16 or second chamber 18). For example, if the parameter were the amount of molten metal in a ladle, when the amount of molten metal M within the ladle is low, the control system could cause the speed of molten metal pump 22 to increase to pump molten metal M at a greater flow rate to raise the level in second chamber 18 and ultimately fill the ladle. As the level of the molten metal within the ladle increased, the control system could cause the speed of molten metal pump 22 to decrease and to pump molten metal M at a lesser flow rate, thereby ultimately decreasing the flow of molten metal into the ladle. The control system could be used to stop the operation of molten metal pump 22 should the amount of the molten metal within a structure, such as a ladle, reach a given value or if a problem were detected. The control system could also start pump 22 based on a given parameter.

[0068] One or more devices 58 may be used to measure one or more parameters of molten metal M, such as the depth, weight, level and/or volume, in any structure or in multiple structures. Device 58 may be located at any position and more than one device 58 may be used. Device 58 may be a laser, float, scale to measure weight, a sound or ultrasound sensor, or a pressure sensor. Device 58 is shown as a laser to measure the level of molten metal in FIGS. 5 and 11-13.

[0069] The control system may provide proportional control, such that the speed of molten metal pump 22 is proportional to the amount of molten metal within a structure. The control system could be customized to provide a smooth, even flow of molten metal to one or more structures such as one or more ladles or ingot molds with minimal turbulence and little chance of overflow.

[0070] FIG. 14 shows a control panel 70 that may be used with a control system. Control panel 70 includes an “auto/man” (also called an auto/manual) control 72 that can be used to choose between automatic and manual control. A “device on” button 74 allows a user to turn device 58 on and off. An optional “metal depth” indicator 76 allows an operator to determine the depth of the molten metal as measured by device 58. An emergency on/off button 78 allows an operator to stop metal pump 22. An optional RPM indicator 80 allows an operator to determine the number of revolutions per minute of a predetermined shaft of molten metal pump 22. An AMPS indicator 82 allows the operator to determine an electric current to the motor of molten metal pump 22. A start button 84 allows an operator user to start molten metal pump 22, and a stop button 84 allows a user to stop molten metal pump 22.

[0071] A speed control 86 can override the automatic control system (if being utilized) and allows an operator to increase or decrease the speed of the molten metal pump. A cooling air button 88 allows an operator to direct cooling air to the pump motor.

[0072] Having thus described different embodiments of the invention, other variations and embodiments that do not depart from the spirit thereof will become apparent to those skilled in the art. The scope of the present invention is thus not limited to any particular embodiment, but is instead set forth in the appended claims and the legal equivalents thereof. Unless expressly stated in the written description or claims, the steps of any method recited in the claims may be performed in any order capable of yielding the desired product or result.