MOLTEN METAL TRANSFER STRUCTURE AND METHOD

Abstract

The invention relates to systems for transferring molten metal from one structure to another. Aspects of the invention include a transfer chamber constructed inside of or next to a vessel used to retain molten metal. The transfer chamber is in fluid communication with the vessel so molten metal from the vessel can enter the transfer chamber. A powered device, which may be inside of the transfer chamber, moves molten metal upward and out of the transfer chamber and preferably into a structure outside of the vessel, such as another vessel or a launder.

Claims

1. A method for transferring molten metal from a vessel, wherein the vessel comprises: (a) a cavity configured for retaining molten metal; (b) an intake section in communication with the cavity; (c) a transfer well in communication with the intake section; (d) an outlet in communication with the transfer well; and (e) one or more brackets attached to the vessel, wherein the brackets are configured to position an insert next to an outside surface of the vessel such that an inlet of the insert aligns with the outlet of the vessel; the method comprising the steps of: positioning the insert next to the outside surface of the vessel so that the inlet of the insert aligns with the outlet of the vessel, and operating a molten metal pump positioned in the insert to move molten metal from the vessel into the insert.

2. The method of claim 1, wherein the pump comprises a rotor and drive shaft and that further includes the step of positioning the rotor and the drive shaft at least partially in an uptake section of the insert.

3. The method of claim 1, wherein the insert inlet has a cross-sectional area and the insert includes an uptake section that has a second cross-sectional area, wherein the second cross-sectional area is larger than the cross-sectional area.

4. The method of claim 3, wherein the insert uptake section is cylindrical.

5. The method of claim 3, wherein the insert uptake section comprises a first vertical section with a first cross-sectional area and a second vertical section having the second cross-sectional area, the second cross-sectional area being adjacent the insert inlet, and the second cross-sectional area is smaller than the first cross-sectional area.

6. The method of claim 1, wherein the insert comprises one or more brackets for positioning the molten metal pump in a cavity of the insert, and that further comprises the step of attaching the molten metal pump to the one or more brackets.

7. The method of claim 6, wherein the one or more brackets comprises two metal beams that extend from a first side wall of the insert to a second side wall of the insert, and each of the metal beams is connected to the first side wall of the insert and the second side wall of the insert.

8. The method of claim 7, wherein each beam is L-shaped.

9. The method of claim 3, wherein the insert has three walls outside of the vessel and has a fourth wall that is an outer wall of the vessel.

10. The method of claim 6, wherein the insert includes an uptake section and wherein the one or more brackets and the uptake section are configured such that when the molten metal pump is positioned in the insert the rotor is partially or entirely within the uptake section.

11. The method of claim 1 that further includes a launder connected to an outlet of the insert, and that further includes the step of pumping molten metal through the outlet.

12. The method of claim 1, wherein the pump does not include support posts.

13. The method of claim 2, wherein the rotor comprises one or more rotor blades, and each blade includes: (a) a first portion having (i) a leading edge with a thickness of ⅛″ or greater, (ii) a first upper surface angled to direct molten metal upwards, and (iii) a first bottom surface with an angle equal to or less than the angle of the first upper surface as measured from a vertical axis; and (b) a second portion integrally formed with the first portion, the second portion having (i) a second upper surface angled to direct molten metal upwards, the angle of the second upper surface being greater than the angle of the first upper surface as measured from the vertical axis, and (ii) a second bottom surface, the second bottom surface having an angle greater than the angle of the first bottom surface as measured from the vertical axis.

14. The method of claim 2, wherein the molten metal pump further includes a superstructure for supporting a pump motor.

15. The method of claim 2, wherein the drive shaft includes a motor shaft and a rotor shaft, and that further includes the step of constructing the rotor shaft with a height sufficient to position the rotor at least partially in the uptake section.

16. The method of claim 2 that further includes the step of constructing a drive shaft with a height sufficient to position the rotor at least partially in the uptake of the insert.

17. The method of claim 2 that further includes the step of constructing the rotor with a diameter that is 1/32″ to 1⅛″ less than the diameter of the inlet of the insert.

18. The method of claim 6 that further includes the step of constructing one or more pump brackets configured to connect the pump to the one or more brackets attached to the insert.

19. The method of claim 1, wherein the transfer well has three side walls and a top surface.

20. The method of claim 1, wherein a pump is positioned in the insert and the pump comprises a motor, a drive shaft having a first end connected to the motor and extending into the uptake section, and the drive shaft having a second end connected to a rotor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is a top, perspective view of a system according to the invention, wherein a transfer chamber is included installed in a vessel designed to contain molten metal.

[0032] FIG. 2 is a top view of the system according to FIG. 1.

[0033] FIG. 3 is a side, partial cross-sectional view of the system of FIG. 1.

[0034] FIG. 4 is a top view of the system of FIG. 1 with the pump removed.

[0035] FIG. 5 is a side, partial cross-sectional view of the system of FIG. 4 taken along line B-B.

[0036] FIG. 6 is a cross-sectional view of the system of FIG. 4 taken along line C-C.

[0037] FIG. 7 is a top, perspective view of another system in accordance with the invention.

[0038] FIG. 8 is a top view of the system of FIG. 7 attached to or formed as part of a reverbatory furnace.

[0039] FIG. 9 is a partial, cross-sectional view of the system of FIG. 8.

[0040] FIG. 10 is a top view of an alternate system according to the invention.

[0041] FIG. 11 is a partial, cross-sectional view of the system of FIG. 10 taken along line A-A.

[0042] FIG. 12 is a partial, cross-sectional view of the system of FIG. 10 taken along line B-B.

[0043] FIG. 13 is a top view of a rotor according to the invention.

[0044] FIGS. 14 and 15 are side views of the rotor of FIG. 13.

[0045] FIGS. 16 and 17 are top, perspective views of the rotor of FIG. 13 at different, respective positions of the rotor.

[0046] FIG. 18 is a top view of the rotor of FIG. 13.

[0047] FIG. 19 is a cross-sectional view of the rotor of FIG. 18 taken along line A-A.

[0048] FIG. 20 is a side, partial cross-sectional view of an alternate embodiment of the invention.

[0049] FIG. 21 is a top, partial cross-sectional view of the embodiment of FIG. 20.

[0050] FIG. 22 is a partial, cross-sectional side view showing the height relationship between components of the embodiment of FIGS. 20-21.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0051] Turning now to the drawings, where the purpose is to describe a preferred embodiment of the invention and not to limit same, systems and devices according to the invention will be described.

[0052] The invention includes a transfer chamber used with a vessel for the purpose of transferring molten metal out of the vessel in a controlled fashion using a pump, rather than relying upon gravity. It also is more preferred than using a transfer pump having a standard riser tube (such as the transfer pumps disclosed in the Background section) because, among other things, the use of such pumps create turbulence that creates dross and the riser tube can become plugged with solid metal.

[0053] FIGS. 1-6 show one preferred embodiment of the invention. A system 1 comprises a vessel 2, a transfer chamber 50 and a pump 100. Vessel 2 can be any vessel that holds molten metal (depicted as molten metal bath B), and as shown in this embodiment is an intermediary holding vessel. Vessel 2 has a first wall 3 and a second, opposite wall 4. Vessel 2 has support legs 5, inner side walls 6 and 7, inner end walls 6A and 7A, and an inner bottom surface 8. Vessel 2 further includes a cavity 10 that may be open at the top, as shown, or covered. An inlet 12 allows molten metal to flow into the cavity 10 and molten metal flows out of the cavity 10 through outlet 14. At the top 16 of vessel 2, there are flat surfaces 18 that preferably have metal flanges 20 attached. A tap-out port 22 is positioned lower than inner bottom surface 8 and has a plug 22A that can be removed to permit molten metal to exit tap-out port 22. As shown, inner bottom surface 8 is angled downwards from inlet 12 to outlet 14, although it need not be angled in this manner.

[0054] A transfer chamber according to the invention is most preferably comprised of a high temperature, castable cement, with a high silicon carbide content, such as ones manufactured by AP Green or Harbison Walker, each of which are part of ANH Refractory, based at 400 Fairway Drive, Moon Township, Pa. 15108, or Allied Materials. The cement is of a type know by those skilled in the art, and is cast in a conventional manner known to those skilled in the art.

[0055] Transfer chamber 50 in this embodiment is formed with and includes end wall 7A of vessel 2, although it could be a separate structure built outside of vessel 2 and positioned into vessel 2. Wall 7A is made in suitable manner. It is made of refractory and can be made using wooden forms lined with Styrofoam and then pouring the uncured refractory (which is a type of concrete known to those skilled in the art) into the mold. The mold is then removed to leave the wall 7A. If Styrofoam remains attached to the wall, it will burn away when exposed to molten metal.

[0056] Transfer chamber 50 includes walls 7A, 52, 53 and 55, which define an enclosed, cylindrical (in this embodiment) portion 54 that is sometimes referred to herein as an uptake section. Uptake section 54 has a first section 54A, a narrower third section 54B beneath section 54A, and an even narrower second section 54C beneath section 54B. An opening 70 is in communication with area 10A of cavity 10 of vessel 2.

[0057] Pump 100 includes a motor 110 that is positioned on a platform or superstructure 112. A drive shaft 114 connects motor 110 to rotor 500. In this embodiment, drive shaft 114 includes a motor shaft (not shown) connected to a coupling 116 that is also connected to a rotor drive shaft 118. Rotor drive shaft 118 is connected to rotor 500, preferably by being threaded into a bore at the top of rotor 500 (which is described in more detail below).

[0058] Pump 100 is supported in this embodiment by a brackets, or support legs 150. Preferably, each support leg 150 is attached by any suitable fastener to superstructure 112 and to sides 3 and 4 of vessel 2, preferably by using fasteners that attach to flange 20. It is preferred that if brackets or metal structures of any type are attached to a piece of refractory material used in any embodiment of the invention, that bosses be placed at the proper positions in the refractory when the refractory piece is cast. Fasteners, such as bolts, are then received in the bosses.

[0059] Rotor 500 is positioned in uptake section 54 preferably so there is a clearance of ¼ or less between the outer perimeter of rotor 500 and the wall of uptake section 54. As shown, rotor 500 is positioned in the lowermost second section 54C of uptake section 54 and its bottom surface is approximately flush with opening 70. Rotor 500 could be located anywhere where it would push molten metal from area 10A upward into uptake section 54 with enough pressure for the molten metal to reach and pass through outlet 14, thereby exiting vessel 2. For example, rotor 500 could only partially located in uptake section 54 (with part of rotor 500 in area 10A, or rotor 500 could be positioned higher in uptake section 54, as long as it fit sufficiently to generate adequate pressure to move molten metal into outlet 14.

[0060] Another embodiment of the invention is system 300 shown in FIGS. 7-12. In this embodiment a transfer chamber 320 is positioned adjacent a vessel, such as a reverbatory furnace 301, for retaining molten metal.

[0061] System 300 includes a reverbatory furnace 302, a charging well 304 and a well 306 for housing a circulation pump. In this embodiment, the reverbatory furnace 302 has a top covering 308 that includes three surfaces: first surface 308A, second, angled surface 308B and a third surface 308C that is lower than surface 308A and connected to surface 308A by surface 308B. The purpose of the top surface 308 is to retain the heat of molten metal bath B.

[0062] An opening 310 extends from reverbatory furnace 302 and is a main opening for adding large objects to the furnace or draining the furnace.

[0063] Transfer well 320, in this embodiment, has three side walls 322, 324 and 326, and a top surface 328. Transfer well 320 in this embodiment shares a common wall 330 with furnace 302, although wall 330 is modified to create the interior of the transfer well 320. Turning now to the inside structure of the transfer well 320, it includes an intake section 332 that is in communication with a cavity 334 of reverbatory furnace 302. Cavity 334 includes molten metal bath B when system 300 is in use, and the molten metal can flow through intake section 332 into transfer well 320.

[0064] Intake section 332 leads to an enclosed section 336 that leads to an outlet 338 through which molten metal can exit transfer well 320 and move to another structure or vessel. Enclosed section 336 is preferably square, and fully enclosed except for an opening 340 at the bottom, which communicates with intake section 332 and an opening 342 at the top of enclosed section 336, which is above and partially includes the opening that forms outlet 338.

[0065] In order to help form the interior structure of well 320, wall 330 has an extended portion 330A that forms part of the interior surface of intake section 332. In this embodiment, opening 340 has a diameter, and a cross sectional area, smaller than the portion of enclosed section 336 above it. The cross-sectional area of enclosed section 336 may remain constant throughout, may gradually narrow to a smaller cross-sectional area at opening 340, or there may be one or more intermediate portions of enclosed section 336 of varying diameters and/or cross-sectional areas.

[0066] A pump 400 has the same preferred structure as previously described pump 100. Pump 400 has a motor 402, a superstructure 404 that supports motor 402, and a drive shaft 406 that includes a motor drive shaft 408 and a rotor drive shaft 410. A rotor 500 is positioned in enclosed section 336, preferably approximately flush with opening 340. Where rotor 500 is positioned it is preferably ¼″ or less; or ⅛″ or less, smaller in diameter than the inner diameter of the enclosed section 336 in which it is positioned in order to create enough pressure to move molten metal upwards.

[0067] A preferred rotor 500 is shown in FIGS. 13-19. Rotor 500 is designed to push molten metal upward into enclosed section 336. The preferred rotor 500 has three identically formed blades 502, 504 and 506. Therefore, only one blade shall be described in detail. It will be recognized, however, that any suitable number of blades could be used or that another structure that pushes molten metal up the enclosed section could be utilized.

[0068] Blade 504 has a multi-stage blade section 504A that includes a face 504F. Face 504F is multi-faceted and includes portions that work together to move molten metal upward into the uptake section. The rotor preferably comprises one or more rotor blades, wherein each blade includes: (a) a first portion having (i) a leading edge with a thickness of ⅛″ or greater, (ii) a first upper surface angled to direct molten metal upwards, and (iii) a first bottom surface with an angle equal to or less than the angle of the first upper surface as measured from a vertical axis; and (b) a second portion integrally formed with the first portion, the second portion having (i) a second upper surface angled to direct molten metal upwards, the angle of the second upper surface being greater than the angle of the first upper surface as measured from the vertical axis, and (ii) a second bottom surface, the second bottom surface having an angle greater than the angle of the first bottom surface as measured from the vertical axis. As shown in FIGS. 13-17, each rotor blade 504 has a bottom 504B having a leading edge 504C and angled surface 504F. Angled surface 504F meets surface 504E, which is more vertical than surface 504F in order to push molten metal at least partially outward. Each blade 504 has a top surface 504D.

[0069] A system according to the invention may also utilize a standard molten metal pump, such as a circulation or gas-release (also called a gas-injection) pump 20. Pump 20 is preferably any type of circulation or gas-release pump. The structure of circulation and gas-release pumps is known to those skilled in the art and one preferred pump for use with the invention is called “The Mini,” manufactured by Molten Metal Equipment Innovations, Inc. of Middlefield, Ohio 44062, although any suitable pump may be used. The pump 20 preferably has a superstructure 22, a drive source 24 (which is most preferably an electric motor) mounted on the superstructure 22, support posts 26, a drive shaft 28, and a pump base 30. The support posts 26 connect the superstructure 22 a base 30 in order to support the superstructure 22.

[0070] Drive shaft 28 preferably includes a motor drive shaft (not shown) that extends downward from the motor and that is preferably comprised of steel, a rotor drive shaft 32, that is preferably comprised of graphite, or graphite coated with a ceramic, and a coupling (not shown) that connects the motor drive shaft to end 32B of rotor drive shaft 32.

[0071] The pump base 30 includes an inlet (not shown) at the top and/or bottom of the pump base, wherein the inlet is an opening that leads to a pump chamber (not shown), which is a cavity formed in the pump base. The pump chamber is connected to a tangential discharge, which is known in art, that leads to an outlet, which is an opening in the side wall 33 of the pump base. In the preferred embodiment, the side wall 33 of the pump base including the outlet has an extension 34 formed therein and the outlet is at the end of the extension.

[0072] In operation, the motor rotates the drive shaft, which rotates the rotor. As the rotor (also called an impeller) rotates, it moves molten metal out of the pump chamber, through the discharge and through the outlet.

[0073] A circulation or transfer pump may be used to simply move molten metal in a vessel towards a transfer chamber according to the invention where the pump inside of the transfer chamber moves the molten metal up and into the outlet.

[0074] Alternatively, a circulation or gas-transfer pump 1001 may be used to drive molten metal out of vessel 2. As shown in FIGS. 20-22, a system 1000 as an example, has a dividing wall 1004 that would separate vessel 2 into at least two chambers, a first chamber 1006 and a second chamber 1008, and any suitable structure for this purpose may be used as dividing wall 1004. As shown in this embodiment, dividing wall 1004 has an opening 1004A and an optional overflow spillway 1004B, which is a notch or cut out in the upper edge of dividing wall 1004. Overflow spillway 1004B is any structure suitable to allow molten metal (designated as M) to flow from second chamber 1008, past dividing wall 1004, and into first chamber 1006 and, if used, overflow spillway 1004B may be positioned at any suitable location on wall 1004. The purpose of optional overflow spillway 1004B is to prevent molten metal from overflowing the second chamber 1008, by allowing molten metal in second chamber 1008 to flow back into first chamber 1006 or vessel 2 or other vessel used with the invention.

[0075] At least part of dividing wall 1004 has a height H1, which is the height at which, if exceeded by molten metal in second chamber 1008, molten metal flows past the portion of dividing wall 1004 at height H1 and back into first chamber 1006 of vessel 2. Overflow spillway 1004B has a height H1 and the rest of dividing wall 1004 has a height greater than H1. Alternatively, dividing wall 1004 may not have an overflow spillway, in which case all of dividing wall 1004 could have a height H1, or dividing wall 1004 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 1008 exceeded H1. H1 should exceed the highest level of molten metal in first chamber 1006 during normal operation.

[0076] Second chamber 1008 has a portion 1008A, 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 1008 flows past wall 1008A and out of second chamber 1008 rather than flowing back over dividing wall 1004 and into first chamber 1006.

[0077] Dividing wall 1004 may also have an opening 1004A that is located at a depth such that opening 1004A is submerged within the molten metal during normal usage, and opening 1004A is preferably near or at the bottom of dividing wall 1004. Opening 1004A preferably has an area of between 6 in..sup.2 and 24 in..sup.2, but could be any suitable size.

[0078] Dividing wall 1004 may also include more than one opening between first chamber 1006 and second chamber 1008 and opening 1004A (or the more than one opening) could be positioned at any suitable location(s) in dividing wall 1004 and be of any size(s) or shape(s) to enable molten metal to pass from first chamber 1006 into second chamber 1008.

[0079] Optional launder 2000 (or any launder according to the invention) is any structure or device for transferring molten metal from a vessel such as vessel 2 or 302 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 2000 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 2000 may be completely horizontal or may slope gently upward, back towards the vessel. Launder 2000 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 2000 may additionally or alternatively be serviced by robots or cast machines capable of removing molten metal M from launder 20.

[0080] It is also preferred that the pump 1001 be positioned such that extension 31 of base 3000 is received in the first opening 1004A. This can be accomplished by simply positioning the pump 1001 in the proper position. Further the pump may be held in position by a bracket or clamp that holds the pump against the dividing wall 1004, and any suitable device may be used. For example, a piece of angle iron with holes formed in it may be aligned with a piece of angle iron with holes in it on the dividing wall 1004, and bolts could be placed through the holes to maintain the position of the pump 1001 relative the dividing wall 1004.

[0081] In operation, when the motor is activated, molten metal is pumped out of the outlet through first opening 1004A, and into chamber 1008. Chamber 1008 fills with molten metal until it moves out of the vessel 2 through the outlet. At that point, the molten metal may enter a launder or another vessel.

[0082] If the molten metal enters a launder, the launder preferably has a horizontal angle of 0° or is angled back towards chamber 1008 of the vessel 2. The purpose of using a launder with a 0° slope or that is angled back towards the vessel is because, as molten metal flows through the launder, the surface of the molten metal exposed to the air oxidizes and dross is formed on the surface, usually in the form of a semi-solid or solid skin on the surface of the molten metal. If the launder slopes downward it allows gravity to influence the flow of molten metal, and tends to pull the dross or skin with the flow. Thus, the dross, which includes contaminants, is included in downstream vessels and adds contaminants to finished products.

[0083] It has been discovered that if the launder is at a 0° or horizontal angle tilting back towards the vessel, the dross remains as a skin on the surface of the molten metal and is not pulled into downstream vessels to contaminate the molten metal inside of them. The preferred horizontal angle of any launder connected to a vessel according to aspects of the invention is one that is at 0° or slopes (or tilts) back towards the vessel, and is between 0° and 10°, or 0° and 5°, or 0° and 3°, or 1° and 3°, or a backward slope of about ⅛″ for every 10′ of launder length.

[0084] Having thus described some embodiments of the invention, other variations and embodiments that do not depart from the spirit of the invention 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 result.