US 3092030 A
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Description (OCR text may contain errors)
June 4, 1963 w. G. WUNDER 3,092,030
Filed July 10, 1961 INVEN 0R.
75750177 6' 2; er az/fzfl AT RNEY United States Patent 3,092,030 PUMP Filed July 10, 1961, Ser. No. 122,720 1 Claim. (Cl. 103-103) This invention relates to a pump for lifting and conveymg molten metal and more particularly to a pump adapted for immersion in a corrosive molten metal such as aluminum.
Modern light metal foundry operations require that molten metal such as aluminum or magnesium be conveyed in relatively small quantities at frequently recurring intervals from a holding furnace or the like where the metal is stored in a molten condition to molds or the like, as for example, the shot sleeve of a cold chamber die casting machine. Many attempts have been made in the past to develop satisfactory ways of pumping molten metal in this manner. The great difficulty has been to provide a pump in which the parts exposed to contact with the molten metal will resist the deleterious attack thereof and which is of sufiiciently simple construction to permit its fabrication of suitable corrosion-resistant materials. In the case of-pumping molten aluminum, metal pump parts are unsatisfactory since high melting point metals, such as iron, are dissolved when in contact with molten aluminum in spite of the fact that the temperature of the molten aluminum may be approximately one half the melting temperature of the iron. The life of pump parts which operate immersed in molten aluminum is as a consequence relatively short, in the neighborhood of a few days or less when used continuously. Moreover, the iron which is thusly introduced into the molten aluminum in substantial quantities constitutes an undesirable impurity which may adversely affect the quality of the castings. Other molten metals attack and adversely affect other higher melting temperature metals in a similar manner.
It is a basic object of this invention to provide a pump for pumping molten metals such as aluminum which is efiicient in its operation and which may be readily and economically formed of materials capable of resisting deleterious attack by the molten metal.
These and other objects are accomplished by a novel pump structure consisting essentially of a housing containing a vertically disposed cylindrical passage therein including an inlet and an outlet and rotatably mounted therein a rotor consisting of a circular body defined by a circular periphery and top and bottom oppositely disposed faces or surfaces. The top of the rotor body is attached to a vertically mounted pump shaft. The base of the rotor is provided with an opening extending upwardly therein. A series of open-ended passages extend from this opening radially outwardly and upwardly to an offset or reduced diameter portion extending downwardly from the top of the rotor. In operation, when the rotor is immersed in molten metal and caused to spin, the molten metal is drawn into the opening within the rotor and thence impelled radially outwardly to the reduced diameter portion thereof. A vertically disposed vane projecting into the pump passage translates the rotational movement of the molten metal to upward and substantially lineal motion.
Other objects and advantages of the invention will become apparent from the following detailed description of the invention, reference being had to the accompanying drawings, in which:
FIGURE 1 is an elevation view in partial cross section of a pump embodying the present invention;
FIGURE 2 is an end view taken along line 2-2 of FIGURE 1; and
FIGURE 3 is an exploded view showing various components of the pump of FIGURE 1 in perspective.
Referring to the drawings, FIGURE 1 illustrates one embodiment of the pump made in accordance with the present invention which is particularly designed for pumping molten metal from a retaining crucible or furnace into the trough of a cold chamber-type die casting machine. In general, the pump is of a centrifugal type, including a housing 10 having a cylindrical passage 11 therein which forms an inlet opening 12 at the base thereof. An outlet opening 14 is provided near the top of the housing. Operating Within the housing 10 is an impeller or rotor 16 mounted on a shaft 18. The top 15 of the housing is closed except for the provision of an opening 21 through which the rotor shaft passes.
As may be seen most clearly in relation to FIGURE 3, the impeller 16 consists of an annular block having a top side 17 and a bottom side 19 and having a reduced diameter portion 20 extending downwardly from the top side 17. Centrally of the impeller at the base thereof there is provided an annular intake chamber 22. A plurality of diagonal passages 24 extend from the intake chamber 22 to the reduced diameter portion 20.
The impeller 16 is threadably attached to a shaft 18 preferably consisting of a steel core 28 and an outer body portion 30. The steel core 28 permits the body portion 30 to be made of a relatively weak or brittle refractory material which is capable of resist-ing the erosion of the molten aluminum. Conveniently the impeller may be formed to have a passage entirely through the center thereof, the base 32 of the shaft serving as a closure or top of the intake chamber 22 of the impeller.
The passage 11 in the housing portion 10 of the pump includes an annular portion 34 at the base thereof adapted to receive the impeller 16 so as to provide a small clearance 36 therebel-ow so that when the base of the pump is immersed in molten aluminum the impeller is not apt to engage a rigid surf-ace even if the pump is placed on the base of a crucible. The passage 11 includes a longitudinal vane 38 interiorly thereof extend-ing from a position just above the impeller 16 to a point in close proximity to the pump outlet 14.
The pumping action of the pump may be readily understood in relation to FIGURE 3. To pump the molten aluminum the unit is inserted in the molten metal to a sufficient extent to cause the intake chamber 22 of the impeller 16 to be immersed in the molten aluminum and filled therewith. Normal hydrostatic pressure will, of course, cause the molten aluminum to flow into the intake chamber 12 of the impeller. When the impeller is caused to spin, the aluminum is thrown to the periphery of the chamber 22 and onward through the diagonal openings 24 to the annular space 23 formed between reduced portion 20 of the impeller and passage 11. The longitudinal vane 3-8 within the chamber 11 causes the whirling motion of the molten aluminum to be translated into linear motion longitudinally of the pump housing passage 11 and onto the outlet 14 thereof.
As previously indicated, the pump of this invention is particularly designed to be formed of relatively brittle refractory materials. The impeller may be formed of a refractory material such as carbon. As previously indicated, the impeller structure preferably involves the use of a steel core 28 as shown in FIGURE 3 which is wrapped with asbestos strip or covered with outher suitable ceramic material. The steel core 28 is cemented to the covering material 30 and takes the torque in driving the impeller.
In some instances, the pump components may be made of a heat-resistant alloy such as the well known ironnickel-chromium types to which is fused a ceramic coating to prevent molten metal such as aluminum from attacking these pump parts when subjected to direct and prolonged contact with such a molten metal. A suit able protective ceramic coating may be applied by first spraying a composition which has a high content of ironnickel-chromium and manganese oxides and a low content of aluminum, then spraying several additional coatings, each having a progressively greater aluminum oxide content so that the final spray coat has a very high aluminum oxide content and then fusing and bonding these coatings to the base metal. The simple structure of the pump components simplifies the application of this type of coating.
While the embodiment of the present invention as disclosed herein constitutes a preferred form, it is to be understood that other forms may be adopted without departing from the spirit of the invention.
Apparatus for pumping molten metal from one level to a higher level adapted to be formed of relatively britt le non-metallic refractory materials comprising a longi tud-inal housing having a cylindrical passage therethrough, a rotor mounted on a shaft positioned within said cylindrical passage near the open-ended base of said housing, an outlet conduit communicating with said passage above said rotor, said rotor comprising a generally circular body defined by a circular periphery and upper and low er opposite faces, an opening in said lower face and extending into said body, said shaft extending into said body at the upper face and being fixed to said body, said shaft being formed of a nonmetallic refractory and having a metal core, said circular body having a reduced diameter portion at the upper end thereof, said reduced diameter portion and said passage forming an annular recess, and open-ended passages extending radially through said body from said opening to a plurality of locations around the periphery of said reduced diameter portion of said body, whereby when said rotor assembly is rotating in a molten metal bath the molten metal is drawn upwardly into said opening and thence; impelled radiallyoutwardly to saidrecess, and a longitudinal vane formed integrally with said housing extending from, a point above said rotor to a point near to said outlet, said vane being operative to translate rotational to longitudinal movement within said housing.
References Cited in the file ofsthis, patent UNITED STATES PATENTS 849,030 Valliquette Apr, 2, 1907 1,832,890 Antisell ,Nov. 2.4, 1931 2,493,467 Sunnen Jan. 3, 1950 2,528,210 Stewart Oct. 31, 1950 2,658,454 Greene NOV. 10, 1953 2,905,093 Raut et al. Sept. 22, 1959 2,948,524 Sweeney et a1 Aug. 9, 1960 3,048,384 Sweeney et a1. Aug. 7, 1962