US1876261A - Apparatus for casting metals and metalloids - Google Patents

Description

Sept. 6, 1932. G. PEMETZRlEDE-R APPARATUS FOR CASTING METALS AND METALLOIDS 2 Sheets-Sheet Filed Aug. 29, 1930 fm ezzior Sept. 6, 1932'. G. PEMETZRIEDER I 1,876,261

APPARATUS FOR CASTING METALS AND METALLOIDS Filed Aug. 29, 1950 z-sneets-sheet 2 Patented Sept. 6, 1932 UNITED STATES PATENT OFFICE.

GEOBG PEMETZRIEDER, F BERLIN-TEMPELHOF, GERMANY APPARATUS FOR CASTING METALS AND ME'IALLOIDS Application filed August 29, 1930, Serial No. 478,766, and in Germany December 3, 1929.

The beneficial eifect of using centrifugal force in casting metals and metalloids is well known. Up to the. present time rotating drums have been used in which the metal rises by the effect of centrifugal force at the lnteriorside of the drum and forms a ring upon solidification. In another known arrangement the vertical sideof the drum is composed of a series of closed molds, filled in radial direction by the molten metal. In still other arrangements single closed molds are employed which are set up around the axis of rotation of the apparatus and filled by radial channels. In doingso it is usual to fill the several molds by means of a common central runner and radial side channels.

' These procedures have the disadvantages that either they do not employ closed forms, or, in the case of radial filling of closed molds,

'0 they cause zones of difierent density to appear in the castings, due to the fact that the centrifugal forces increase in pro ortion to the distance from the center 0 rotation. The method according to the invention ofl'ers 5' the means for removing these disadvantages and rendering the casting moldreally useful for all fields of use.

The new method depends upon an arrangement of closed forms which avoids increasing the centrifugalforce within the form by filling the forms in rising direction through a channel at the inferior end of the mold.

For carrying out this method an apparatus is made use of in which closed forms are arranged around the axis of rotation of the casting machine. Coaxial to the axis of rotation there is a central runner from the base of which radial channels run into the lower ends of the molds. According to the invention the molds are arranged so that their greatest dimensions lie parallel to the axis of rotation. Consequently the central runner, radiating channels, and molds form a communicating system within which the pressure in the mold keeps in equilibrium with the centrifugal force in such a way that the various zones of the cast metal are under substantially the same pressure. In order to make this physical law ellicacious according to 60 the invention inlarger molds too, if for technical reasons one cannot arrange each mold with its greates extensionparallel to the axis of rotation, one has to provide for each mold several casting channels, the number and-position of .which are such that the part of the u mold corresponding to each channel has its greatest extension parallel to the axis of rotation.

According to another feature of the invention, when employing several channels for 0 one form, the casting material is brought into the several parts of the mold at'the same time and in quantities proportional to the volume of the respective parts of the mold. In'this way it is possible to make irregularly formed, a unsymmetrical castings with the described homogeneity. By this procedure the otherwise inevitable faults or cracks are also avoided. The regulation of the quantity is accomplished in 'a simple way be varying the cross-section of the channel; the regulation of the moment when the metal enters the mold by making the channels more or less crooked. The shape of the mold may make it necessary to diminish the back-pressure arising in the 78 mold. This is done by positioning the form obliquely to the axis of rotation, because then, according to the law of the parallelogram of forces, only the vertical component of the pressure within the form is effective. f Two examples of carrying out the process according to the invention are shown in the annexed drawings.

Fig. 1 is a vertical form of apparatus.

Fig. 2 is a horizontal section on the line 2-2 of Fig. '1.

Fig. 3 is a vertical central section of another form of apparatus.

Fig. 4 is a diagram of the forces existing no central section of one in the molds shown in Fig. 3.

Fig. 5 is a diagrammatic view correspond ing to a horizontal section on the line 5-5 of Fig. 3.

On a rotating plate a which is moved in 96 some suitable way there is arran ed a base plate 7) to which are fixed a num r of single forms closed in themselves and consisting of two parts. Those forms are arranged around the middle of axis of rotation 100 d. At the top the apparatus is closed by a lid 0. It has in the middle 9. hole f, through which the casting material is. brought to a separate runner g belowit. The axis of this runner coincides with the axis *of the centrifugal apparatus. To the lower end of the runner side channels are connected in star formation, the outer ends of which open into the forms a. Preferably these channels are formed by recesses i in the base plate 6 and a cover plate 7".

The material is brought to the rotating apparatus by the hole f. It fills the central runner g and the inertia of this column of molten material largely overcomes the tendency of the friction of the rotating wall of the runner to set it rotating. Therefore the radial channels h one after the other move around the column of liquid material and always take their material from different parts of the column. Something similar to a milling process takes place which causes a thorough intermixture-of the material. Therefore the material which runs into the molds through the star shaped channels L is already condensed. As the channels lead directly into the forms, there is also an excellent centrifugal efi'ect, so that condensed ma terial enters the forms with great rapidity under the influence of centrifugal force. Therefore the material completely fills the forms, even with a temperature as low as red heat. The centrifugal efi'ect helps the condensation of the material resulting from the causes above mentioned. so that on the whole a product is obtained which with respect to its mechanical qualities. strength, expansion and so on answers the highest demands.

The further principles of the invention in question are represented in the Figures 3 to 5. On a rotatable plate k is a base Z.

I upon which inclined molds m are mounted central runner p. From the base of the runner side channels 1", s, t. in the base lead out to the foot of each mold.

It will be remembered that one of the im Dortant features of the invention is the utilization of the counter-pressure exerted by the weight of the casting material to counteract the effect of unequal centrifugal forces. From Fig. 4'in which the line -AB schematically represents the oblique position of the forms (less than 90 with respect to the axis of the central runner) it is evident that the casting material in the communicating system formed in the central runner, the'side channels, and the mold, does not exert a counter-pressure equal to its full weight, but only to that part of its weight which corre. sponds to the proportion of the vertical component of force AC to the length AB. By

varying the angle of inclination the counterpressure can be varied accordingly.

The eifect of making the side channels of different cross-section and different arrangement of the lines is schematically illustrated in Fig. 5. As it is necessary for the mass to be cast to enter into the different parts of one form at the same time, as nearly as possible the channel 1", which feeds a'smallcr part of the casting, must be smaller in crosssection than the channel 8, which feeds a larger part of the casting. The channel I? through which the molten material is brought to a part of the mold nearer the central rlmner has tobe given a course that retards the arrival of the material at the mouth of the mold.

Having now particularly described and ascertained the nature of my said invention and in what manner it is to be performed, what I claim is:

1. Centrifugal casting apparatus, comprising a rotatable base, molds arranged on said base with one of their greater dimensions inclined to the horizontal, a central runner coaxial with said base, and side channels radiating from the foot of said runner and leading into the bottom of said molds.

2. Centrifugal casting apparatus, comprising a rotatable base, molds arranged on said base in upright position, a central runner coaxial with said base, and side channels radiating from the foot of said runner and leading into the bottom of said molds, each of said molds having a plurality of said side channels associated therewith and terminating in different parts thereof, said molds being arranged so that each part thereof associated with one of said channels has one of its greater dimensions in a non-horizontal position.

3. Centrifugal casting apparatus, comprising a rotatable base, molds arranged on said base in upright position, a central runner coaxial with said base, and side channels radiating from the foot of said runner and leading into the bottom of said molds. each of said molds having a plurality of said side channels associated therewith and terminating in different parts thereof, the several side of the respective parts of the mold into which a central runner concentric with the axis of said table and having such a small diameter that the centrifugal force exerted upon the metal in said runner when said table is in rotation is smaller than the weight of said metal; a plurality of closed molds mounted symmetrically on said table, each in upright position, said molds being spaced outward from said runner a substantial distance; and covered channels connecting the feet of said molds with the foot of said runner, whereby said molds are filled in rising direction.

6. Centrifugal casting apparatus, comprising a rotatable base, molds arranged on said base with one of their greater dimensions inclined to the horizontal at such an angle that the centrifugal forces upon the molten material in the mold are balanced by the counter-pressure exerted by the weight of the molten material in the mold, a central runner coaxial with said base, and side channels radiating from the foot of said runner and leading into the bottom of said mold.

'In testimony whereof I aflix my signature. GEORG PEMETZRIEDER.

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