US3048384A

US3048384A - Pump for molten metal

Info

Publication number: US3048384A
Application number: US858283A
Authority: US
Inventors: Victor D Sweeney; Walter U Kaji
Original assignee: Metal Pumping Services Inc
Current assignee: Metal Pumping Services Inc
Priority date: 1959-12-08
Filing date: 1959-12-08
Publication date: 1962-08-07
Anticipated expiration: 1979-08-07

Description

1962 v. D. SWEENEY ETAL 3,048,384

PUMP FOR MOLTEN METAL Filed Dec. 8, 1959 3 Sheets-Sheet 1 I U4 33 20 19 I8 INVENTORS VICTOR D. SWEENEY BY WALTER u. KAJI ATTORNEYS Aug. 7, 1962 Filed Dec. 8, 1959 V. D. SWEENEY ETAL PUMP FOR MOLTEN METAL 3 Sheets-Sheet 2 I l I II M! 1" INVENTORS V/CTOF? D SWEENEY y WALTER KAJ/ ATTORNEYS 1962 v. D. SWEENEY ETAL 3,048,384

PUMP FOR MOLTEN METAL 3 Sheets-Sheet 3 Filed Dec. 8, 1959 INVENTORSI VICTOR D. SWEENEY BY WALTER U. KAJ/ M 9L WW ATTORNEYS United States Patent 3,048,384 PUMP FOR MOLTEN METAL Victor D. Sweeney, Merion Station, Pa., and Walter U. Kaji, Chagrin Falls, Ohio, assignors to Metal Pumping Services, Inc., Cleveland, Ohio, a corporation of Ohio Filed Dec. 8, 1959, Ser. No. 858,283 4 Claims. (Cl. 266-38) The present invention relates to pumps and, more particularly, to pumps for lifting and conveying molten metal.

It has long been an object of the art to develop satisfactory means for pumping molten metal to locations where work is to be done with the metal or to the metal. Although a number of pump designs have been proposed for the pumping of molten metal, most of these pumps were not commercially feasible, due to the costly and elaborate designs which were believed to be required because of the corrosive character of the molten metal. These designs embodied large, hollow casings formed of refractory materials. The relatively bulky mass of these hollow casings necessitated the gradual cooling and curing of the casings over a period of many weeks to form casings which would possess even reasonable commercial life. These complicated manufacturing procedures greatly increased the cost of such pumps.

An additional problem in the selection of a suitable design for a pump to be used with molten metal is the character of the particular metal being handled. For example, with certain metals, such as aluminum, impurities therein tend to settle to the bottom of the molten bath, while with heavier metals, such as certain zinc alloys, the impurities tend to rise to the surface of the bath. As a result, if the pump is of such a design that the molten metal is drawn from the bottom of the bath, the pump will be particularly useful for the pumping of the heavier metals in which the impurities accumulate near the surface-of the bath. However, if this same pump were employed for the pumping of the molten aluminum, the metal discharged by the pump would be severely contaminated with impurities because of the molten metal having been withdrawn from the bottom of the bath where the impurities had collected.

In spite of the fact that these problems were well known for a long period of time, the pumps available did not fulfill the need for a pump of simple design and of a low manufacturing cost which would be capable of moving a variety of molten metals under different operating conditions.

Therefore, it is an object of the present invention to provide a pump for conveying molten metal which overcomes the above-mentioned disadvantages of the prior art structures.

Another object of the invention is to provide a pump for molten metal which can be used to draw the metal from either the upper or the lower parts of the molten bath, and which can be converted quickly and conveniently from one type of operation to the other.

Another object of the invention is to provide a .novel shrouded impeller structure for pumps, useful for the conveying of molten metal.

Still another object of the invention is to provide a pump which will permit controlled intermittent flow simply and conveniently.

These and other objects and advantages of the invention will be apparent from the following description and accompanying drawing in which:

FIG. 1 is an elevational view, with parts broken away, of a pump embodying the present invention in operative association with a molten metal bath from which metal is to be pumped; I

FIG. 2 is a sectional view of another form of pump embodying the invention;

ice

FIG. 3 is a side elevation of the impeller of the pump shown in FIG. 1;

FIG. 4 is a plan View of an element of the pump shown in FIG. 1;

FIG. 5 is a sectional view taken on line 5-5 of FIG. 2;

FIG. 6 is an elevational view, with parts broken away, of another form of pump embodying the invention;

FIG. 7 is a side elevation, with parts broken away, of the pump shown in FIG. 6; and

FIG. 8 is an enlarged elevational view of the pump shown in FIG. 6, showing the details of the connection between the pump shaft and the driving means.

The numeral 10 in FIG. 1 illustrates a bath of molten metal disposed in a suitable container, such as a holding furnace or the like, having a floor 11 and side walls 12 lined with a material having refractory properties and resistive to attack by the molten metal.

One embodiment of a pump made according to the present invention is shown in partially submerged position in the molten metal bath, and it may be seen that the form illustrated comprises a pump foot body 13 which is suspended above the floor 11 of the container for the molten metal bath. The body '13 is in the form of a slab and has a major bore 14. Axially aligned with the bore 14 is a reduced bore 15. An offset bore 16 extends partially downwardly through the body 13. A volute member 17 is positioned in the upper portion of the major bore 14 and is supported in such position by a spacer ring 18 which is positioned within the bore 14, as indicated in FIG. 1.

It will be understood that a volute member is preferred but that advantages of the invention can be realized without the employment of such a volute member. In its stead, there may be employed a projection on the trailing side of the intersection between the bore 14 and the bore 16 (the term trailing being used with respect to the direction of rotation of the impeller, described below). 4

The pump impeller 19 is generally circular in form and has a depending skirt portion 33 which surrounds an axially extending internal cavity or bore 20. Passages 21 extend through the skirt portion of the impeller and communicate with the bore 20 disposed in the skirt or peripheral portion of the impeller. The passages 21 are preferably of constant cross section and slant back-wardl'y with respect to the direction of rotation of the impeller. The impeller has a threaded bore 22 coaxial with the bore 20 by which the impeller is threadedly engaged on the lower end of the pump shaft 24. The space between the impeller 19 and the portions of the foot body 13 and ring 18 which form the pump chamber is such as to establish a running fit suitable for the metal being pumped and act as molten-metal-lubricated bearings for the impeller. If desired, the impeller 19 and/or the foot body 13 may contain insert rings, such as rings 23 and 30, at points which would be most susceptible to wear, to permit replacement of worn portions of the pump assembly easily and conveniently.

Column members

25 and 26 are provided which are engaged with the pump foot body 13, as indicated in the drawing. Column 25 may be threadedly engaged with the body 13, while column 26, which comprises a hollow conduit, is received within the offset bore 16 so as to extend down partially to meet the bore 14.

At it upper end, column 25 may be provided with suitable metal studs, and may be bolted to a horizontal plate 27. Mounted on plate 27 is a vertical plate 28 which supports an air motor 29. The motor is connected to a universal joint 31, which in turn is connected to a metal cap 32 threadedly attached to the upper end of pump shaft 24.

The upper end of the hollow column or conduit 26 is received in a hollow spout body 34. The hollow spout body is supported above horizontal plate 27 by a pair of bolts 35 and a transverse strap 36. The outlet end of the spout body 34 leads to the point at which it is desired to discharge the molten metal.

Sheets

37 and 38 of asbestos fibers or other insulating material may be positioned on the upper and lower sides of the spout 34.

If the above-described pump is to be employed to convey molten aluminum, it may be desired to draw the molten metal into the pump from a point in the bath which is above the foot body 13, as shown in FIG. 2. In such a case, the pump may be readily adapted for such pumping operation by removing the impeller 19 and shaft 24 from the apparatus and substituting a second pump impeller 19a and a second shaft 24a. Impeller 19a is similar to impeller 19 but i in an inverted position with respect to impeller 19, i.e., the inlet opening formed by bore 20 extends upwardly rather than downwardly, as in impeller 19. However, the radially extending passages which communicate with the bore 29a of impeller 19a slant backwardly with respect to the direction of rotation of the impeller, similarly to the passages 21 of impeller 19, rather than slanting in the opposite direction, as would be the case if impeller 19 were merely inverted.

The shaft 24a connecting impeller 19a with the motor is somewhat longer in length than shaft 24 employed with impeller 19. This is due to the fact that shaft 24 is threaded into bore 22 located in the top of impeller 19, whereas, shaft 24a is threaded into bore 22a, which is located in the bottom of impeller 19a.

Thus, when a molten metal such as aluminum is being pumped, the pump impeller would be positioned as in FIG. 2. The molten metal would flow downwardly into bore 20a and then radially outwardly through passages 21a, upwardly through conduit 26, and finally, outwardly along the interior of the spout body 34. In contrast, if a metal such as molten zinc is being pumped, the impeller of the pump assembly would be positioned as shown in FIG. 1, with the molten metal being drawn upwardly through bore 20, radially outwardly through passages 21,

and then, as described above, upwardly through conduit 26 and out of spout body 34.

Another form of the pump of the invention is shown in FIGS. 6, 7, and 8. The pump is similar to the one shown in FIG. 1 with a foot body 13, a pump impeller 19, a pump shaft 24, and an air motor 29. Outlet conduit 26 is bolted to a horizontal plate 27 which also acts as a support for a hollow spout body 34. A vertical support or plate 28 is fastened to horizontal plate 27 and the air motor 29 attached to the vertical plate 28.

In place of universal joint 31, as shown in FIG. 1, connecting the motor 29 and the pump shaft 24, a connecting assembly is provided which permits the raising and lowering of the shaft 24 and impeller 19. This movement is accomplished by means of an air cylinder 41, the lower part of which is attached to horizontal plate 27, and the upper part to a lug 42.

As shown in FIG. 8, the lug 42 is connected to a sleeve 43 which in turn is atfixed to the pump shaft 24 by means of a coupling 44. The upper portion of sleeve 43 is slidably connected to motor 29 through a coupling 45. The sleeve 43 and the coupling 45 are connected by means of a pin 46 which is affixed to coupling 45 and which engages a slot 47 in sleeve 43.

When air is permitted to enter air cylinder 41 through inlet opening 48, a piston 49 rises forcing horizontal lug 42 to move upward. Upward movement of the horizontal lug 42 causes the sleeve 43, the shaft 24, and the impeller 19 which are all connected also to rise. Thus, the impeller 19 is removed from the pump chamber in foot body 13 and the pumping of the molten metal stopped without stopping or changing the speed of rotation of the motor or the shaft and impeller attached thereto.

To start the pumping action, the air pressure in cylinder 41 is released causing the piston 49 to slide back into the cylinder and causing the horizontal lug 42 to move downward. The descent of horizontal lug 42 results in the lowering of the impeller 19 which is afiixed thereto through shaft 24 and sleeve 43. The downward movement of the assembly is aided by a spring 51 which is attached to horizontal lug 42 and to horizontal plate 27.

The distance of travel of the impeller 19 may be controlled by controlling the movement of horizontal lug 42. This may be accomplished by employment of a stop rod 52 affixed to vertical support 28 by means of bracket 53.

Bolts

54 and 55 may be affixed to stop rod 52 above and below the horizontal lug 42. The position of these bolts may be varied on top rod 52 to change the distance of travel of horizontal lug 42. This adjustment in turn will control the distance of travel of impeller 19.

Advantageously, impeller 19 is raised or lowered in the pump foot body 13 a distance sufiicient to move the passages 21 of the impeller out of the pump chamber of foot body 13. Preferably, the impeller 19 is raised with respect to the foot body 13 to a point which will permit the molten metal in the outlet conduit 26 to flow back down into the bath rather than remain in the conduit with the possibility that it might be cooled to the point of solidification. If the molten metal should solidify in the outlet conduit 26, it would be necessary to apply heat to the conduit to remelt the metal before pumping could resume. Thus, it is apparent that movement of the impeller to permit the emptying of the molten metal from the outlet conduit is preferred.

As pointed out above, in place of the air cylinder 41 employed to raise and lower the pump assembly from the foot body 13 as shown in FIGS. 6, 7, and 8, other apparatus which function in a similar manner, such as a hand-operated lever, a hydraulic cylinder, or an electric motor in combination with a screw drive advantageously might be employed.

In a like manner, air cylinder 41 or other means which may be employed to raise and lower the impeller from the foot body, together with the sleeve 43, may be incorporated in the pump shown in FIGS. 1 and 2 of the drawing. The modification of the pump in FIGS. 1 and 2 in this manner not only permits the drawing of molten metal from a point in the bath above or below the foot body as previously described, but by this modification, the starting and stopping of the flow of molten metal from the pump is possible without stopping or changing the speed of rotation of the impel er body 19, the shaft 24 or the motor 29.

The portions of the pump which are exposed to contact with the molten metal or which are immersed in the molten metal bath, such as pump foot body 13, volute member 17, ring 18, impeller 19, shaft 24,

columns

25 and 26, and spout body 34, are all formed of a suitable material which will resist corrosive attack of the molten metal. The above-mentioned parts may be fabricated from a non-metallic refractory material having high resistance to attack from the molten metal, and which will not introduce contaminants into the molten metal. For example, structural carbonaceous and siliceous refractory materials, such as graphite, graphitized carbon, claybonded graphite, carbon-bonded graphite, silicon carbides, aluminum silicates, and other bonded refractory mixtures containing such materials, may be successfully employed.

Fabricated parts of such refractory materials may be subjected to simple machining operations, such as the boring of holes, the tapping of threads, and the like. In general, the larger openings, such as the major bore 14 of the pump body 13, are not formed by machining but are formed in the molding of the part.

As shown in the foregoing description, the present invention provides a new pump for conveying molten metal which may be used to draw metal from either the upper or lower parts of a molten bath and which may be con verted quickly and conveniently from one type of operation to the other. This convertibility of the pump facilitates the pumping of difierent molten metals by a simple conversion step. Thus, when pumping a metal such as aluminum in which the impurities collect on the bottom of the bath, the pump may be assembled to permit drawing of the metal from the upper part of the bath. Conversely, when heavier metals such as certain zinc alloys are to be pumped with the result that the impurities will tend to be near the surface of the bath, the pump may be assembled to draw molten metal from the bottom of the bath.

Moreover, the present invention provides a pump which will permit controlled intermittent flow simply and conveniently without starting, stopping or changing the speed of rotation of the impeller, the pump shaft or the driving means. Also, the invention provides a pump which is of simple design and which may be manufactured at substantially lower cost than pumps previously used for conveying molten metal.

It is apparent from the above discussion that various modifications may be made in the pump design described. For example, the location of outlet conduit 26 and spout body 34 may be modified or changed to provide for the delivery of the molten metal in a suitable manner for a particular bath operation. Also air motor 29 and the pump shaft 24 may be connected by the use of a different coupling means than that shown in FIGURE 8 of the drawing.

Since as pointed out above, various modifications may be made within the scope of the invention, the invention is not intended to be limited to the particular pump structures described in detail herein, except as may be required by the appended claims.

What is claimed is:

1. In a pump for molten metal, comprising the combination of (a) an upper frame, (b) a lower foot body, in the form of a refractory slab having upper and lower faces, suspended from the frame for immersion in molten metal to be pumped and defining a pump chamber therein and coaxial, upper and lower, vertical bores extending into the pump chamber through said upper and lower faces of the slab, respectively, (0) a refractory centrifugal impeller body having a periphery of cylindrical contour and an inlet that opens axially into one end only thereof, said impeller body projecting into said pump chamber with its cylindrical axis vertical for rotation therein about said axis, and (d) a vertically disposed refractory pump shaft depending from said frame and connected in coaxial driving relationship with said impeller body; the improvement in said combination wherein said coaxial upper and lower bores into said pump chamber are of the same diameter and said impeller body extends, in one of two relatively inverted positions, upwardly and downwardly into said bores and is journaled in both with a free running fit exposed for lubrication by molten metal surrounding said slab while drawing molten metal axially into the impeller body at its inlet end for discharge radially into said pump chamber, whereby said molten metal will be drawn by the impeller body from above or below said foot body according to whether the impeller body is mounted therein with its inlet end facing upwardly or downwardly.

2. The improved combination of claim 1 wherein said coaxial upper and lower bores into said pump chamber are defined, at least in part, by refractory bearing rings set into said refractory slab.

3. The improved combination of claim 1 additionally including means acting between said frame and said pump shaft for axially shifting said pump shaft and impeller body relative to said slab between an operative position of the impeller body in said pump chamber and an at least partially withdrawn and inoperative position of the impeller body, whereby the discharge of molten metal rom the impeller body into said pump chamber may be stopped and started without changing the speed of rotation of said shaft and impeller body.

4. The improved combination of claim 1 wherein said coaxial upper and lower bores into said pump chamber are defined, at least in part, by refractory bearing rings set into said refractory slab, and said combination includes means acting between said frame and said pump shaft for axially shifting said pump shaft and impeller body relative to said slab between an operative position,

of the impeller body in said pump chamber and an at least partially withdrawn and inoperative position of the impeller body, whereby the discharge of molten metal from the impeller body into said pump chamber may be stopped and started without changing the speed of rotation of said shaft and impeller body.

References Cited in the file of this patent UNITED STATES PATENTS 2,383,424 Stephanofi Aug. 21, 1945 2,493,467 Sunnen Jan. 3, 1950 2,528,210 Stewart Oct. 31, 1950 2,779,574 Schneider Jan. 29, 1957 2,808,782 Thompson et a1 Oct. 8, 1957 2,824,520 Bartels Feb. 25, 1958 2,948,524 Sweeney et al. Aug. 9, 1960 FOREIGN PATENTS 808,796 Germany July 19, 1951 954,669 Germany Dec. 20, 1956