EP1522735B1 - Shaft and post assemblies for molten metal pumping apparatus - Google Patents
Shaft and post assemblies for molten metal pumping apparatus Download PDFInfo
- Publication number
- EP1522735B1 EP1522735B1 EP05000809A EP05000809A EP1522735B1 EP 1522735 B1 EP1522735 B1 EP 1522735B1 EP 05000809 A EP05000809 A EP 05000809A EP 05000809 A EP05000809 A EP 05000809A EP 1522735 B1 EP1522735 B1 EP 1522735B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- post
- rod
- sheath
- molten metal
- graphite
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D39/00—Equipment for supplying molten metal in rations
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D7/00—Pumps adapted for handling specific fluids, e.g. by selection of specific materials for pumps or pump parts
- F04D7/02—Pumps adapted for handling specific fluids, e.g. by selection of specific materials for pumps or pump parts of centrifugal type
- F04D7/06—Pumps adapted for handling specific fluids, e.g. by selection of specific materials for pumps or pump parts of centrifugal type the fluids being hot or corrosive, e.g. liquid metals
- F04D7/065—Pumps adapted for handling specific fluids, e.g. by selection of specific materials for pumps or pump parts of centrifugal type the fluids being hot or corrosive, e.g. liquid metals for liquid metal
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/05—Refining by treating with gases, e.g. gas flushing also refining by means of a material generating gas in situ
Definitions
- This invention relates to the construction of a post for a molten metal pump according to the preamble of claim 1.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
- Reciprocating Pumps (AREA)
Description
- This invention relates to the construction of a post for a molten metal pump according to the preamble of
claim 1. - Such a post is for example known from US-A-5 558 505.
- 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. Additionally, the motor is suspended on a superstructure over the bath by posts connected to the base. Rotation of the impeller within the pumping chamber forces the molten metal as desired in a direction permitted by the pumping chamber design.
- 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.
- 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 bath 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.
- Similarly, the shaft connecting the impeller and the motor is constructed of graphite. Often, this shaft component experiences significant stress when occluding matter in the metal bath is encountered and sometimes trapped against the housing. Since graphite does not possess as high a strength as would be desired, it would be helpful to reinforce the leg and shaft components of the pump.
- In addition, graphite can be difficult to work with because different stock may have different thermal expansion rates and/or different grain orientation. This may result in a post and base having divergent and conflicting thermal expansion rates in the molten metal environment. This problem is compounded by the fact that pump construction has historically required cementing the graphite post into a hole in the graphite base. This design provides no tolerance between the components to accommodate divergent thermal expansion. Unfortunately, this can lead to cracking of the base or the post. Accordingly, it would be desirable to have a molten metal pump wherein the mating of a post and a base is achieved in a manner which accommodates divergent thermal expansion tendencies.
- An example of a submergence device is described in U.S. Patent 4,598,899, herein incorporated by reference.-An exemplary degassing apparatus is described in U.S. Patent 4,898,367, herein incorporated by reference. In both devices, a vertically oriented shaft having a impeller/rotor disposed at one end in the molten metal bath is employed. Similar problems arise in these apparatus wherein the components are usually constructed of graphite, and would benefit from an increase in strength.
- Accordingly, it is a primary advantage of this invention to provide a new and improved.
- Additional advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practicing the invention. The advantages of this invention may be realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.
- A molten metal pump comprises a pumping member (such as an impeller or rotor), at least partially enclosed within a housing. A power device is seated on a support above the housing and pumping member. A shaft connects the power device and the pumping member to provide rotation thereof according to the invention at least one, and preferably two to four posts, suspend the housing from the support. Said posts are constructed according to the features of
claim 1. - Further embodiments are defined by the dependent claims.
- Preferably, the outer member is comprised of a graphite, refractory, or ceramic material and the housing is comprised of graphite. Preferably, the rod will be comprised of a heat resistant alloy.
- In a particularly preferred form of the invention, the outer member is comprised of a plurality of generally cylindrically shaped units, aligned along their longitudinal axis. The rod runs down a central bore of each unit to provide a stacked arrangement. Preferably, the lower most unit will include a circumferential protrusion shaped to mate with a recess formed in the top surface of the housing to create a fluid tight seal.
- The accompanying drawings, which are incorporated in and constitute a part of the specification illustrate one embodiment in the invention and, together with the description, serve to explain the principles of the invention.
Of the Drawings: - FIG. 1 is a front elevation view, partially in cross-section, of a molten metal pump which is not part of the present invention;
- FIG. 2 is a side elevation view, also partially in cross-section, of Fig. 1;
- FIG. 3 is a front elevation view, partially in cross-section, of the rod of Fig.1;
- FIG. 4 is a front elevation view, in cross-section, of the inventive sheath of Fig. 1;
- FIG. 5 is a front elevation view, in cross-section, of an alternative post embodiment;
- FIGS. 6, 7 and 8 are front elevation views, in cross-section, of alternative post and base seating arrangements;
- FIG. 9 is a front elevation view, in cross-section, of a segmented post design;
- FIG. 10 is a front elevation view, in cross-section, of an alternative segmented sheath design;
- FIG. 11 is an exploded side elevation view, in cross-section, of an alternative post/base joining arrangement;
- FIG. 12 is an exploded view of section A of Fig. 11 showing the fluid tight joint;
- 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 scope of the invention defined by the appended claims.
- Referring now to Figs. 1 and 2, molten
metal transfer pump 1 is provided. The molten metal pump includes abase assembly 3 having a pumping chamber 5 with an impeller 7 disposed therein. Bearing rings 9 provide mating surfaces between the impeller 7 and thebase assembly 3. Rotation of the impeller 7 forcesmolten metal 11 throughoutlet 13 and upriser tube 15 for transport to another location. - Rotation of impeller 7 is achieved when
motor 17 rotatesshaft 19 by turningshaft coupling 21 provided therebetween. The motor is positioned above thebase assembly 3 on aplatform assembly 22 having aninsulation layer 23, amotor mount bracket 25 and amotor mount plate 26. - Two
post assemblies 27, comprised of arod 29 constructed of a heat resistant alloy material disposed within arefractory sheath 31 suspend thebase assembly 3 below theplatform 22. Preferably, the rod will be constructed of an alloy such as MSA 2000 or MSA 20001 available from Metaullics Systems Co., L.P., 31935 Aurora Road, Solon, Ohio, 44139. The refractory sheath also includes aceramic shield 33 for additional protection against oxidation. The lower end ofrod 19 includescap 35.Cap 35 is disposed within acavity 37 inbase assembly 3. A graphite orrefractory plug 39 is cemented into the lowermost portion of the cavity to seal the area from molten metal. The upper end of therod 29 extends through theinsulation layer 23 and is secured withnut 41 to themotor mount plate 26. Adisc spring 43 or other compression spring is disposed between themotor mount platform 25 andinsulation layer 23. Preferably, an insulating washer (not shown) will be positioned betweenmotor mount plate 26 andspring 43. Tightening ofnut 41 results in compression of thespring 43 and a bias on therod 29 andsheath 31. - - Advantageously this assembly provides a high strength alloy rod connection between the base and motor mount. Of course, it also protects the otherwise degradable rod from the molten metal environment. A further advantage is that the thermal expansion mismatch resulting from divergent grain orientations in a graphite post and a graphite base is eliminated because a graphite post is not rigidly cemented into a hole in the base. Furthermore, the strength of the graphite sheath is increased because it is retained under compression as a result of being squeezed between a
socket 45 and the upper surface ofbase assembly 3. - Turning now to Figure 3, a detailed depiction of
rod 29 is provided. In this embodiment,cap member 35 is welded atweld lines 47 to the lower most end of the rod. Of course, other mechanisms of attachment, including but not limited to, threaded or swaged, are appropriate joining techniques. Figure 4 provides a detailed cross-sectional view of thegraphite sheath 31. - Referring now to Figure 5, an alternative post embodiment is depicted. In this embodiment, the
post 101 again includesrod 103 protected from the molten metal environment bysheath 105.Rod 103 passes through a bore/cavity 106 in abase member 107 and is retained by thecap 109 containing asnap ring 111 having corresponding retaininggrooves cap 109 androd 103, respectively. Again adisk spring 117 andnut 118 are provided, which in concert with theplatform 119 create a bias onrod 103 and a compressive force onsheath 105. - Turning now to Figures 6, 7, and 8, alterative post and base joining techniques are depicted. For example, in Figure 6,
rod 201 extends throughbase 205 and includes a threadedend 202 on whichgraphite cap 203 is secured. In Figure 7, the embodiment of Figure 6 is modified to includeseal members bore 301 is provided in the end ofgraphite post 303 and a threadedgraphite post 305 extends upwardly throughbase member 307 and is mated to the end of thepost 303. An advantage of each design is the ability to create a tension on the post to provide a self-alignment mechanism without the need for a structural use of cement. In this regard, a thermal expansion gap can be provided (see Fig. 11) where cement has been historically required. - Furthermore, the use of a
protrusion 211 on the end cap post/bolt 203/205 in a combination withrecesses 213 on the top and bottom surfaces of the base 205/307 create a fluid tight joint. Accordingly, molten metal does not enter this joint, allowing the post to be removed from the base if a rebuild of the pump is required. - It should be noted that while the present joining mechanisms in Figures 6 through 8 are generally depicted as coinciding to the utilization of a steel alloy rod, these mechanisms for joining a post to a base are equally applicable to a graphite post arrangement. Moreover, the arrangements depicted in Figures 6 through 8 can equally be considered as being constructed of all elements comprised of a combination of steel and graphite/ceramic or graphite/ceramic alone. The advantage provided by these assemblies is that there is no necessity for a cement joint between the post and the base which better accommodates thermal expansion mismatches.
- Turning now to Figure 9, an alternative embodiment of the present invention is provided wherein the
post 401 includes arod 403 and asheath 405. However, in thisembodiment sheath 405 is comprised of the plurality of segmented units. This design is particularly desirable because of the relative ease of forming individual segmented units (A-E) as opposed to an elongated tube. Again, thepost 401 is provided with aspring 407 and ametallic coupling unit 409, which in combination with the motor mount (not shown) creates a compressive force on the sheath segments (A-E). A fluid tight seal is created between each of the individual units as a result of the compressive force, and, may be enhanced by the inclusion of a gasket material (not shown) therebetween. The lower most unit E includes acircumferential protrusion 411 which is seated in arecess 413 in the top surface of thebase 415. Accordingly, a fluid tight seal is achieved. As in any of the other designs herein, a bead of cement-or sealant may be placed around the seatedprotrusion 411 to further protect against unwanted metal seepage. - Referring now to Figure 10, an alternative embodiment of a
segmented sheath 501 is depicted. In this embodiment, the end surfaces of the individual units A-E are cooperatively contoured to facilitate achieving an appropriate mating arrangement. In this regard, a verifiable seating arrangement is provided to assure a metal tight seal is formed between each individual segment. - Turning now to Figure 11, a detailed view of an arrangement mating a graphite post to a graphite base is provided to demonstrate both the desired tolerance for thermal expansion and a desirable configuration for achieving a fluid tight seal. More particularly,
graphite post 601 passes through a hole 603 in a base assembly 605. Threadedgraphite cap member 607 is attached to the lowermost portion ofpost 601. At both of the top and bottom interface ofpost 601 and/or cap -member 607 to the base assembly 605, acooperative protrusion 609 andrecess 611 are provided to create a fluid tight if seal. Referring now to Figure 12, the angled surfaces of the protrusion and recess are depicted. In this manner, a fluid tight mating surface achieved. The mating surfaces may be filled with a gasket material (not shown). A further advantage of the present invention is the tolerance provided bygap 613 for thermal expansion.
Claims (9)
- A molten metal pump post comprising:an elongated rod (29);a sheath (31) receiving the elongated rod such that a first end and a second end of the rod extends from the sheath;a coupling unit (41) at least partially surrounding a first portion of the sheath member proximal the first end of the rod; characterised in thata biasing member (43) at least partially surrounding a portion of the rod adjacent the first end of the rod.
- The post of claim 1, wherein the coupling unit (41) comprises a nut.
- The post of claim 1, wherein the sheath (31) comprises a refractory material.
- The post of claim 1, wherein the sheath (31) further comprises a ceramic shield (33).
- The post of claim 1, wherein the rod (29) comprises a heat resistant alloy.
- The post of claim 1, wherein the biasing member (43) comprises a disc spring.
- The post of claim 1, wherein the sheath (41) includes a circumferential protrusion disposed at one end.
- The post of claim 1, wherein the sheath comprises a plurality of segmented units (405).
- The post of claim 8, wherein an end surface of adjacent segmented units are contoured.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10770198P | 1998-11-09 | 1998-11-09 | |
US107701P | 1998-11-09 | ||
EP99971898A EP1129295B1 (en) | 1998-11-09 | 1999-11-09 | Shaft and post assemblies for molten metal pumping apparatus |
Related Parent Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99971898A Division EP1129295B1 (en) | 1998-11-09 | 1999-11-09 | Shaft and post assemblies for molten metal pumping apparatus |
EP99971898.4 Division | 1999-11-09 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP1522735A2 EP1522735A2 (en) | 2005-04-13 |
EP1522735A3 EP1522735A3 (en) | 2005-11-16 |
EP1522735B1 true EP1522735B1 (en) | 2006-12-20 |
Family
ID=34315388
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP05000809A Expired - Lifetime EP1522735B1 (en) | 1998-11-09 | 1999-11-09 | Shaft and post assemblies for molten metal pumping apparatus |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP1522735B1 (en) |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4598899A (en) * | 1984-07-10 | 1986-07-08 | Kennecott Corporation | Light gauge metal scrap melting system |
US4898367A (en) * | 1988-07-22 | 1990-02-06 | The Stemcor Corporation | Dispersing gas into molten metal |
DE4303759C2 (en) * | 1993-02-09 | 1997-05-15 | Eberhard Maucher | Dosing pump |
US5558505A (en) * | 1994-08-09 | 1996-09-24 | Metaullics Systems Co., L.P. | Molten metal pump support post and apparatus for removing it from a base |
US5944496A (en) * | 1996-12-03 | 1999-08-31 | Cooper; Paul V. | Molten metal pump with a flexible coupling and cement-free metal-transfer conduit connection |
-
1999
- 1999-11-09 EP EP05000809A patent/EP1522735B1/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
EP1522735A2 (en) | 2005-04-13 |
EP1522735A3 (en) | 2005-11-16 |
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