Post-less molten metal pump

Abstract

According to a first embodiment, a molten metal pump having a base defining a pumping chamber and a motor mount adapted to receive a motor is provided. At least two plates extend between opposed sidewalls of the base and the motor mount. A shaft extends between the base and the motor while an impeller is located in the pumping chamber.

Description

POST-LESS MOLTEN METAL PUMPBACKGROUND

[0001] This application claims priority to US Provisional Application No. 63 / 529,434 filed July 28, 2023, the disclosure of which is herein incorporated by reference.

[0002] The present invention relates to an apparatus for pumping molten metal. Particularly, the present invention relates to a mechanical apparatus for moving or pumping molten metal such as aluminum, zinc or magnesium. More particularly, the present invention is related to an apparatus in which a motor is positioned above a molten metal bath and rotates a vertical shaft. The lower end of the shaft drives an impeller or a rotor to impart motion to the molten metal.

[0003] In the processing of molten metals, it is often necessary to pump molten metal from one place to another. When it is desired to remove metal from a vessel, a so-called transfer pump is used. When it is desired to circulate molten metal within a vessel, a so- called circulation pump is used. When it is desired to purify molten metal disposed within a vessel, a so-called gas injection pump is used. In each of these pumps, a rotatable impeller is submerged, typically within a pumping chamber, in the molten metal bath contained in the vessel. A motor is supported on a superstructure over the bath by posts connected to the base. Rotation of the impeller within the pumping chamber forces the molten metal in a direction permitted by the pumping chamber design.

[0004] Mechanical pumps for moving molten metal in a bath historically have a relatively short life because of the destructive effects of the molten metal environment on the material used to construct the pump. Moreover, most materials capable of long term operation in a molten metal bath have relatively poor strength which can result in mechanical failure. In this regard, the industry has typically relied on graphite, a material with adequate strength, temperature resistance and chemical resistance, to function for an acceptable period of time in the harsh molten metal environment.

[0005] While graphite is currently the most commonly used material, it presents certain difficulties to pump manufacturers. Particularly, mechanical pumps usually require a graphite pump housing submerged in the molten metal. However, the housing is somewhat buoyant in the metal because the graphite has a lower density than the metal.In order to prevent the pump housing from rising in the metal and to prevent unwanted lateral movement of the base, a series of vertical legs are positioned between the pump housing and an overhead structure which acts simultaneously to support the drive motor and locate the base. In addition to functioning as the intermediate member in the above roles, the legs, or posts as they are also called, must be strong enough to withstand the tensile stress created during installation and removal of the pump in the molten metal bath.

[0006] A prior art molten metal pump is described in U.S. Patent 6,887,425, herein incorporated by reference. Referring now to FIGS. 1 & 2, a molten metal transfer pump 1 is provided. The molten metal pump 1 includes a base assembly 3 having a pumping chamber 5 with an impeller 7 disposed therein. Bearing rings 9 provide mating surfaces between the impeller 7 and the base assembly 3. Rotation of the impeller 7 forces molten metal 11 through outlet 13 and up riser tube 15 for transport to another location.

[0007] Rotation of impeller 7 is achieved when motor 17 rotates shaft 19 by turning shaft coupling 21 provided there between. The motor 17 is positioned above the base assembly 3 on a platform assembly 22 having an insulation layer 23, a motor mount bracket 26 and a motor mount plate 25.

[0008] In a preferred embodiment, two post assemblies 27 are shown. The post assemblies 27 are comprised of a rod 29 constructed of a heat resistant alloy material disposed within an inner member 30 and an outer sheath 31 suspend the base assembly 3 below the platform 22. The inner member 30 is disposed between the rod 29 and the outer sheath 31. The inner member can be a material to wet out molten metal that may penetrate the outer sheath. The inner member can comprise fiberfrax, graphoil or other similar material, including but not limited to compressible ceramics.

[0009] Preferably, the rod is constructed of an alloy such as MSA 2000 or MSA 2001. The outer sheath 31 includes a ceramic shield for additional protection against oxidation, erosion, corrosion, etc. The lower end of rod 29 includes cap 35. Cap 35 is disposed within a cavity 37 in base assembly 3. A graphite or refractory plug 39 is cemented into the lowermost portion of the cavity 37 to seal the area from molten metal. Plug 39 is such that its diameter is sufficiently large to include the rod 29 andboth the inner member 30 and outer sheath 31 , while still sealing the connection within the housing. The upper end of the rod 29 extends through the insulation layer 23 and is secured with nut 41 to motor mount plate 26. A disc spring 43 or other compression spring is disposed between the motor mount platform 25 and insulation layer 23. Preferably, an insulating washer (not shown) will be positioned between motor mount plate 26 and spring 43. Tightening of nut 41 results in compression of the spring 43 and a bias on the rod 29 and inner 30 and outer 31 sheaths.

[0010] While the pump design of FIGS 1 & 2 has become the state of the art in the industry, the cost associated with high strength alloy materials can create competitive pressure. The present disclosure is directed to an alternative design that alleviates this issue.BRIEF DESCRIPTION

[0011] According to a first embodiment, a molten metal pump having a base defining a pumping chamber is provided. A motor mount adapted to receive a motor is also provided. At least two plates extend between opposed sidewalls of the base and the motor mount. A shaft extends between the base and the motor with an impeller is located in the pumping chamber.

[0012] According to another embodiment, a molten metal pump support is provided. The support is a substantially planar rectangular ceramic plate having a first edge including at least one ridge. The ridge is configured to engage a pump base. The plate includes a second edge configured to mate with a motor mount.BRIEF DESCRIPTION OF THE DRAWINGS / APPENDIXS

[0013] FIG. 1 is a front elevation view, partially in cross-section, of a prior art molten metal pump;

[0014] FIG. 2 is a side elevation view of the pump of FIG. 1, also partially in crosssection;

[0015] FIG. 3 is a front elevation view of a pump in accordance with one aspect of the present invention;

[0016] FIG. 4 is a side elevation view of the pump of FIG. 3;

[0017] FIG. 5 is a top perspective view of the pump of FIG. 3; and

[0018] FIG. 6 is a bottom perspective view of the pump of FIG. 3.DETAILED DESCRIPTION

[0019] Reference will now be made in detail to the present preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. While the invention will be described in connection with a preferred embodiment, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention defined by the appended claims.

[0020] Referring now to FIGS. 3-6 a molten metal pump 300 is shown having plates 301 extending between base 303 and motor mount 305. The plates 301 can be formed of ceramic. The plates 301 can optionally be formed of multiple layers.

[0021] The plates 301 can include contoured (e.g. rounded) ends 304 to facilitate the flow of molten metal thereover. The plates 301 may also include a plurality of passages (see for example passages 306 in FIG. 4) which facilitate flow of molten metal through the plate 301 while preventing the flow of rocks / debris there through. Passages 306 can be of a size and distribution suitable to permit a desirable flow of molten metal through the plate but prevent damaging rocks from passing through, 25mm or less in diameter, for example.

[0022] Motor mount 305 includes a first platform 307 and a second platform 309. First platform 307 is designed to receive a first edge of each plate 301 . The plates 301 can be attached to the first platform 307 by, for example, bolts or a wedge retaining device 310.

[0023] Each plate 301 includes a second edge including a pair of inwardly extending ridges 311 (upper) and 313 (lower). Each ridge is disposed in a notch 312 (upper) and 314 (lower) formed in base 303. The notches can be located at an edge of the base 303. Accordingly, plates 301 have a shallow “C” shaped region that can be compression fit into engagement with base 303. Ridges 311 and 313 can also be cemented to base 303.

[0024] The first 307 and second 309 platforms are spaced from one another via rods 315. Motor 317 rests upon second platform 309. A shaft 319 extends between motor 317 and an impeller 321 disposed in a pumping chamber 323 in base 303. More particularly, motor coupling 325 receives a first end of shaft 319. A cooling fin 327 can be provided which receives air from blower 328 via conduit 330 to reduce the temperature between the molten metal bath and motor 317.

[0025] First platform 307 can include a shaft seal 329 to help prevent metal penetration between platform 307 and shaft 319. A suitable seal can be a calcium silicate insert.

[0026] A riser 331 engages base 303 at a first end and extends through first platform 307 where it can engage a spout or a transfer system. The base, riser and shaft can be comprised of graphite or ceramic.

[0027] The plates 301 typically can have a height less than the rods. The distance provided between platform 307 and platform 309 spaces motor 317 above the molten metal bath to improve temperature control. First platform 307 can include a heat resistant, molten metal resistant material 333. For example, a porous ceramic fiber or a granular fill material can be employed.

[0028] The base 303 can have a length of X and the plates 301 can have a length of at least 75% of X, or at least 90% of X. In select embodiments the plates have a length greater than a height. The plates can be substantially planar with a first edge configured to attach to the motor mount and a second edge having a ridge configured to overlap or penetrate the base. Substantially planar as used herein means that the first edge and the second edge are substantially (e.g. within 10°) vertically aligned when the pump is assembled.

[0029] An advantage of the design is the elimination of high cost alloy rods of the prior art designs and the associated cost savings.

[0030] Thus, it is apparent that there has been provided in accordance with the present invention, a molten metal pump that fully satisfies the objects, aims, and advantages as set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art like of the foregoing description. Accordingly, it isintended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the appended claims.

Claims

WHAT IS CLAIMED IS:1 . A molten metal pump comprised of a base defining a pumping chamber and a motor mount adapted to receive a motor, at least two plates extending between said base and said motor mount, a shaft extending between said base and said motor, and an impeller located in said pumping chamber and attached to said shaft.

2. The pump of claim 1 wherein said base is comprised of graphite or ceramic.

3. The molten metal pump of claim 1 wherein said motor mount comprises a first platform receiving said plates and a second platform spaced above the first platform.

4. The molten metal pump of claim 3 including at least three elongated rods extending between the first platform and the second platform.

5. The molten pump of claim 4 wherein said rods have a sufficient length to include a cooling device between the first platform and second platform.

6. The molten pump of claim 4 wherein the plates are secured to said first platform and the motor is supported on the second platform.

7. The molten metal pump of claim 6 wherein a shaft coupling secured to the motor and a shaft secured to the impeller are interconnected between the first platform and the second platform.

8. The molten metal pump of claim 7, wherein the first platform includes a heat-insulating material.

9. The molten metal pump of claim 8, wherein the material comprises a ceramic fiber.

10. The molten metal pump of claim 1 wherein said plates are comprised of ceramic.11 . The molten metal pump of claim 1 wherein said plates are substantially planar and include a first edge having a means configured to attach to the motor mount and a second edge having a ridge configured to overlap or penetrate said base.

12. The molten metal pump of claim 11 wherein said plates have two ridges.

13. The molten metal pump of claim 11 wherein said base includes a chamfer or recess that receives said ridge.

14. The molten metal pump of claim 1 wherein said base has a length of X and said plates have a length of at least 75% of X, or at least 90% of X.

15. The molten metal pump of claim 1 wherein said plates have a length greater than the width of the base.

16. The molten metal pump of claim 1 wherein said plates are cemented to the base.

17. The molten metal pump of claim 1 wherein said plates extend between opposed sidewalls of the base and the motor mount.

18. The molten metal pump of claim 3 further including a riser having a first end engaging the base and a second end attached to the first platform.

19. The molten metal pump of claim 1 wherein said plates include a plurality of holes.

20. A molten metal pump support comprising: a substantially planar rectangular body comprised of ceramic having a first edgeincluding at least one ridge and a second edge configured to mate with a motor mount.

21. The support of claim 20 wherein said first edge includes a second ridge disposed at least generally parallel to the at least one ridge.

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