Patent Grant
6843640
1. Field of the Invention
This invention relates generally to the art of processing and treating molten metal, molten alloys, molten salts, or any other molten materials (hereinafter collectively referred to as “molten materials”).
2. Discussion of the Art
In the course of processing molten materials, it is often necessary to transfer the molten materials from one vessel to another or to circulate the molten materials within a vessel. Pumps for processing molten materials are commonly used for these purposes. The pumps can also be used for other purposes, such as to inject purifying gases into the molten materials being pumped. A variety of pumps as described are available from Metaullics Systems Co., L.P., 31935 Aurora Road, Solon, Ohio 44139.
In the case where a molten material is melted in a reverbatory furnace, the furnace is typically provided with an external well in which a pump is disposed. When it is desired to remove molten materials from the vessel, a transfer pump is used. When it is desired to circulate molten materials within the vessel, a circulation pump is used. When it is desired to modify molten materials disposed within the vessel, a gas injection pump is used.
In each of these pumps, a rotatable impeller is disposed within a cavity or housing of a base member that is immersed in a molten material. Upon rotation of the impeller, the molten material is pumped through an outlet or discharge opening and processed in a manner dependent upon the type of pump being used. The impeller itself is supported for rotation in the base member by means of a rotatable shaft. The shaft is rotated by a motor provided at the shaft's upper end. Several support posts extend from a motor support platform to the base member for supporting and suspending the base member within the molten material. In addition, risers may extend upward from the base member for providing a path or channel for the molten materials to exit through.
Although pumps of the foregoing type have been in effective operation for several years, they still suffer from a variety of shortcomings. For example, graphite or ceramic (i.e. refractory materials) are typically the materials used for constructing many of the components of pumps used for processing molten materials because of its low cost, relative inertness to corrosion, and its thermal shock resistance. Although graphite has advantages when used for certain components of molten material pumps, it is not the most advantageous material to be used for complicated shapes and mechanically stressed components.
Rather, it is preferable to make these types of components, e.g. support posts, risers and rotating shafts, from a metallic material, such as iron based alloys or steel, since metallic materials are considerably stronger per pound than graphite. The problem with using these materials is that the base member and impeller are typically constructed from graphite (due to its wear characteristics) and it is difficult to maintain a connection between metallic and graphite components. Such a difficulty arises because of the differences in thermal expansion experienced by these materials. Accordingly, bolts and conventional fasteners are generally not feasible connecting mechanisms. Moreover, the simplest connection would be for the metallic shaft to include a circular threaded male member which is configured to be received within a threaded female member of the graphite impeller.
A second problem arises in connection with attaching a metallic shaft to a graphite impeller. Particularly, because graphite is a relatively weak material, the graphite threads of the impeller are easily stripped upon shaft rotation.
Even when the two components to be connected are of the same material, such as the base and riser of a pump for processing molten zinc or molten magnesium, there are connection problems. For example, the use of bolts and fasteners as a connecting mechanism do not provide optimal strength.
A third problem with known molten material pumps is that the pump components are often manufactured with clearances, tolerances, etc. which permit molten materials to escape from the cavity or housing of the base member. Because the pressure outside the base member is much less than that within the base member, the molten materials naturally gravitate toward the crevices created by the clearances and tolerances. Accordingly it is difficult to maintain an effective seal within the base member's housing.
A fourth problem associated with the foregoing molten material pumps is that the shafts of these pumps have a tendency to grow in length at elevated temperatures due to thermal expansion. The increased length often pushes the pump out of alignment. Similarly, the riser can bend or move during operation and push the pump out of alignment.
Accordingly, a need exists in the art of processing molten materials to provide a molten material pump having an improved (1) sealing assembly, (2) self-aligning shaft, (3) shaft-to-impeller connection, (4) impeller design, and (5) connection assembly for other pump components.
In accordance with one aspect of the present invention, a molten material pump includes a base member defining a chamber within which an impeller is disposed. A rotatable shaft is operatively connected to the impeller. The rotatable shaft has a first end and a second end. The second end of the shaft has a non-circular shape dimensioned to mate with a cooperating non-circular shaped opening in the impeller. A motor is operatively connected to the rotatable shaft for driving the rotatable shaft.
In accordance with another aspect of the present invention, a connecting assembly for interconnecting components of a molten material pump includes a first mounting member connected to a first pump component. The first mounting member has a shape configured to fit within a cooperating recess of a second mounting member connected to a second pump component. The first mounting member includes a first upper dimension and a second lower dimension configured to mate with a first upper dimension and a second lower dimension respectively of the cooperating recess. The first mounting member and cooperating recess of the second mounting member are shaped to form a locking relationship between the second lower dimension of the first mounting member and the first upper dimension of the cooperating recess.
In accordance with another aspect of the present invention, an impeller for a molten material pump includes a substantially cylindrical body having an upper surface, a lower surface, and a peripheral sidewall. A plurality of passages extend through the body of the impeller. A plurality of grooves are defined in the peripheral sidewall of the impeller body.
In accordance with another aspect of the present invention a molten material pump includes a base member defining a chamber housing an impeller. A rotatable shaft has an upper shaft portion connected to a motor and a lower stub shaft connected to the impeller. The lower stub shaft is not rigidly connected to the upper shaft portion so that the stub shaft is free to move in an axial direction.
In accordance with another aspect of the present invention a molten material pump includes a base member defining a chamber housing an impeller. A pump seal member is disposed on a top surface of the base member. The pump further includes a rotatable shaft having a first end connected to a driving means and a second end connected to the impeller. A deflector plate is operatively connected to the rotatable shaft and disposed on top of the pump seal. The deflector plate is sufficiently weighted to compress the seal member against the base member. In a preferred embodiment, the deflector plate is at least 9.921 kilograms (4.5 pounds).
In accordance with another aspect of the present invention, an impeller for a molten material processing system includes a body having an upper surface, a lower surface and a peripheral sidewall. A plurality of passages extend through the body of the impeller for receiving a molten material. A non-circular shaped opening extends axially into the body of the impeller for receiving an associated shaft.
In accordance with another aspect of the present invention, a rotatable shaft for a molten material processing system includes an elongated member having a first end attachable to a motor and a second end attachable to an impeller. The second end of the elongated member has a non-circular shape.
In accordance with another aspect of the present invention, a connecting assembly for interconnecting components of a molten material pump includes a first mounting member connected to a first pump component. The first mounting member includes a shape configured to slidingly engage a cooperating recess of a second mounting member connected to a second pump component. The first mounting member and cooperating recess are shaped to form a locking relationship therebetween.
In accordance with another aspect of the present invention, an impeller/rotatable shaft assembly for a molten material pump includes an elongated shaft member having a first end attachable to a motor and a second end attachable to an impeller. The second end of the elongated member has a circular shape. The assembly further includes an impeller body having an upper surface, a lower surface and a peripheral sidewall. A circular opening extends axially into the body of the impeller for receiving the circular second end of the elongated shaft member. The circular opening and circular second end of the elongated shaft member are concentric and share a central axis. The central axis is offset from an axis of rotation of the elongated shaft.
One advantage of the present invention is the provision of an improved connection assembly between components of a molten material pump, for example between a base member and a post and/or riser.
Another advantage of the present invention is the provision of an improved connection between an impeller and a rotating shaft of a molten material pump.
Another advantage of the present invention is the provision of an impeller having grooves machined into its peripheral surface which enhances the sealing characteristics of a pump assembly.
Another advantage of the present invention is the provision of a deflector plate which weighs on and enhances the sealing characteristics of the pump sealing assembly.
Yet another advantage of the present invention resides in the ability of the molten material pump to maintain effective operation and alignment after thermal expansion of the rotating shaft has occurred.
Still another advantage of the present invention resides in the ability of the molten material pump to maintain proper alignment upon bending or movement of the support riser during operation.
Still other benefits and advantages of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed specification.
The invention may take physical form in certain parts and arrangements of parts, several embodiments of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof and wherein:
a is a side view of an impeller in accordance with the present invention;
b is a top view of the impeller shown in
a is a side view of a shaft in accordance with the present invention;
b is a top view of an impeller in accordance with the present invention;
c is a cross-sectional view of a molten material pump in accordance with the present invention;
d is a plan view of an alternate embodiment of a shaft/impeller assembly in accordance with the present invention;
a is a cross-sectional view of a portion of a molten material pump in accordance with another embodiment of the present invention;
b is a plan view of a stub shaft in accordance with the embodiment shown in
c is a top view of the stub shaft shown in FIG. 8B.
Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents that may be included within the spirit and scope of the invention defined by the appended claims.
Referring now to
The pump is supported by at least one post 24 which extends from the base member 12 to a support plate 26. The post is shown mounted to the support plate via a standard nut/bolt connection. However, any suitable connection is acceptable. The motor 22 is positioned above the support plate 26 and is supported by struts 30 and a motor support platform 34. In the case of a molten material transfer pump, a riser 36 extends from the base member to the support plate 26 much in the same manner as the post 24. A molten material is pumped from the impeller 16, through a discharge opening 38 of the base member 12, and into a channel 42 defined in the riser 36. It must be understood, however, that a riser having a channel defined therein is not necessary for all pumps. For example, in circulation pumps and gas injection pumps, the riser may be replaced with posts similar to post 24, and the molten material simply discharges radially from base member 12.
The pump may optionally include an inlet tube or pipe 44 connected to a lower surface of the base member. Such a tube is provided when a molten material is being pumped from below the base member 12 and it is desired to minimize the length of the pump. Rather than providing a longer pump, it is often less expensive to attach an inlet pipe to the base member in order to achieve a deeper inlet drawing zone.
With reference also to
Accordingly, the present invention provides a connecting assembly 50 which has excellent strength at elevated temperatures and effectively connects a first pump component to a second pump component. For example, the post 24 (which is the first pump component) includes a first mounting member 52 having a shape configured to fit securely within a cooperating recess 54 of a second mounting member 55 attached to the base member 12 (the second pump component). Alternatively, the second mounting member 55 may be integrally formed in the base member rather than being defined in a mounting member attached to the base (e.g. see recess 82 of FIG. 2). The first mounting member and cooperating recess of the second mounting member are shaped to form a locking relationship therebetween (as will be more fully described in connection with FIGS. 3 and 4). Although the post and base member are identified as the first and second pump components in this embodiment, it must be understood that the first and second pump components may be any other pump components that are to be connected.
With further reference to
Although the first mounting member may be received into recess 54 in any suitable manner, it preferably slidingly engages recess 54. More specifically, recess 54 extends transversely across an entire top surface of the second mounting member as shown in FIG. 3. This enables the first mounting member to slide into recess 54 in the direction of arrows A. Alternatively, recess 54 does not extend entirely across the second mounting member. In such an embodiment, the first mounting member is dropped into recess 54 and rotated until tapered portions 58 and 60 engage grooves 66 and 68.
It is important to note that the shape of the first mounting member 52 and recess 54 is not limited to that described above. Rather, the present invention contemplates a mounting member and recess having any shape which adequately achieves an axial locking relationship between the first mounting member and the recess of the second mounting member. For example,
Returning to
With reference also to
The foregoing connecting assembly 50 has been described in connection with a post and base member merely for the purpose of example. However, as noted above, the connection assembly is equally suitable for interconnecting other pump components. For example, the riser 36 is also preferably connected to the base member using the described connection assembly. Moreover, the connecting assembly can be used to connect extension pieces to posts and/or risers. Furthermore, another recess 82 can be provided in the underside of the base member (see
With reference to
To minimize molten material leakage, the peripheral sidewall 90 of the impeller preferably includes slots or grooves 94 defined therein. The grooves extend from an intermediate portion of the impeller sidewall to upper and lower edges of the impeller sidewall. The depth of the grooves for an impeller having a diameter of 9.525 centimeters (3¾ inches) is preferably in the range of 0.08-0.3175 centimeters ({fraction (1/32)}-⅛ inches). The width of the grooves for this particular impeller is preferably in the range of 0.3175-1.27 centimeters (⅛-½ inches). However, it must be appreciated that the depth and width of the grooves of the impeller are not limited to those ranges cited above. The depth and width of these grooves will depend largely on the size of the impeller and the liquid being pumped.
Starting at the intermediate portion of the impeller sidewall, the grooves are preferably angled forward relative to the direction of rotation of the impeller. The forwardly angled grooves capture the molten material and pull it back into the base member's pumping chamber (in the direction of arrows B) by creating an inlet pressure which counteracts the leakage pressure. In essence, a fluid seal is created which facilitates higher flow rates and pressures in the pump.
Alternatively, the grooves 94 can be angled backwards relative to the direction of rotation of the impeller. Such a configuration will facilitate leakage of the fluid being processed. Such a result is beneficial during cleaning of the bearing surfaces or when processing a fluid having a relatively large amount of solid particles, such as a granular material.
Turning now to
In conventional pumps, the shaft is round and includes a male member dimensioned to be threaded into a female receiving portion of a graphite impeller. However, particularly during rotation of a metal shaft, the shaft's male member will strip the graphite threads in the impeller's female member, since graphite is a relatively weak material. In the present invention, the polygonal shaped shaft 18 is fitted within the cooperating polygonal shaped opening 98 in the impeller.
In an alternate embodiment, (see
With reference to
An upper end of the stub shaft preferably includes a universal joint 114 dimensioned to be received within a sleeve 116 of the upper shaft portion. The universal joint preferably takes the shape of a ball-hex (see
Providing a non-rigid or loose connection in the middle of the rotatable shaft allows the upper and lower portions of the shaft to grow in length, as a result of thermal expansion, without affecting operation of the pump. As the length of the stub shaft grows, the increased length can be accommodated within sleeve 114. Similarly, as the length of the sleeve grows, the sleeve can slide over the upper end of the stub shaft. Moreover, if the posts 24 and/or risers 36 distort due to high temperatures and try to push the pump out of alignment, the universal joint permits the impeller to maintain ideal alignment. Furthermore, if the riser bends or moves during operation, the pump will continue to operate properly since the universal joint will enable the stub shaft to pivot.
With specific reference to
In the present invention, a floating deflector plate 126 is disposed on top of the upper sealing block to minimize molten material leakage. The deflector plate is preferably made from a cast iron material and is initially free to move axially along the stub shaft 110. When placed on the upper sealing block, the deflector plate is heavy enough to push or squeeze the sealing surfaces together, thereby minimizing molten material leakage. In this embodiment, the deflector plate preferably weighs at least 9.921 kilograms (4.5 pounds). However, any suitable weight is contemplated by the present invention. Once the deflector plate has been appropriately positioned, a set screw (not shown) is fastened through a key hole 128 defined in the deflector plate. Accordingly, the deflector plate is rigidly mounted to the stub shaft so that it will rotate with the impeller 16.
Thus, it is apparent that there has been provided, in accordance with the present invention, a molten material pump system that fully satisfies the objects, aims and advantages 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. In light of the foregoing description, accordingly, it is intended to embrace all such alternatives modifications, and variations as fall within the spirit and broad scope of the appended claims.
This is a divisional of application Ser. No. 09/775,401, filed Feb. 1, 2001, now U.S. Pat. No. 6,551,060, which claim the benefit of provisioner Application No. 60/178,913, filed Feb. 1, 2000.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3048384 | Sweeney et al. | Aug 1962 | A |
| 3255702 | Gehrm | Jun 1966 | A |
| 3984234 | Claxton et al. | Oct 1976 | A |
| 4426068 | Gimond et al. | Jan 1984 | A |
| 4786230 | Thut | Nov 1988 | A |
| 5092821 | Gilbert et al. | Mar 1992 | A |
| 5330328 | Cooper | Jul 1994 | A |
| 5622481 | Thut | Apr 1997 | A |
| 5634770 | Gilbert et al. | Jun 1997 | A |
| 5685701 | Chandler et al. | Nov 1997 | A |
| 6113363 | Talaski | Sep 2000 | A |
| 6358467 | Mordue | Mar 2002 | B1 |
| 6457940 | Lehman | Oct 2002 | B1 |
| Number | Date | Country | |
|---|---|---|---|
| 20030185679 A1 | Oct 2003 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60178913 | Feb 2000 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 09775401 | Feb 2001 | US |
| Child | 10403954 | US |
