Patent Publication Number: US-3879022-A

Title: Method and apparatus for melting, purifying and alloying metals

Description:
United States Patent [191 Aichert METHOD AND APPARATUS FOR MELTING, PURIFYING AND ALLOYING METALS [76] lnventor: Hans Aichert, Westbahnhofstrasse 15, 6450 Hanau am Main, Germany [22] Filed: June 13, 1973 [21] Appl. No.: 369,434  
 [30] Foreign Application Priority Data June 20, I972 Germany 233l770 [52,] US. Cl 266/34 V; 13/31; 75/49; 75/10 V; 266/33 R [51] Int. Cl. C216 7/10 [58] Field of Search 13/31; 75/10 R, 10 V, 49, 75/65 EB; 266/34 R, 34 V, 39, 33 R, 33 S [56] References Cited UNITED STATES PATENTS 1,497,696 6/1924 Pulliam 266/34 R Apr. 22, 1975 l/l970 Chcng l3/3l X 2/l97l Smith 266/34 V Primary Examiner-Gerald A. Dost Attorney, Agent, or Firm-Joseph F. Padlon ABSTRACT An arrangement in which metallic particles lie on a movable support. The particles have directed onto them an electron beam. While the support executes oscillating motion, the metallic particles retain their position in space at a stationary location. The motion of the support results in rolling of the metal particles. The particles are in molten state and retain their shape through their surface tension characteristics.  
 3 Claims, 2 Drawing Figures METHOD AND APPARATUS FOR MELTING, PURIFYING AND ALLOYING METALS BACKGROUND OF THE INVENTION The present invention relates to an arrangement for melting, purifying, as well as alloying metallic elements which are in molten state and retain their shape through their surface tension. The metallic elements are present in a vacuum on a support which has applied to it a source of energy for the purpose of displacing the support.  
  A process is known in the art of the preceding species in which an energy source in the form of an electron beam is used for melting the metallic elements, and  
 crucible-shaped container means is used for retaining the molten material. This molten material or metallic elements roll into balls or droplets as a result of their surface tension. The support for the metallic molten balls or droplets is movable. At the same time, however, there is no relative motion between the metallic elements and the support when the latter is displaced. The molten material or elements retain essentially their position relative to the support.  
  With the preceding process known in the art, it is not possible to treat the metallic elements for purification purposes, in an effective manner, by a degassing process. The reason for this is that the support screens off the lower portion of the molten material against an interchange of gas with the surrounding environment. Thus, the required gas interchange is only possible through the upper portion of the surface of the molten material. As a result, the oppositely-lying volume elements of the molten material encounter considerable diffusion path lengths. The consequence of this effect is that long processing time intervals are incurred which cannot be tolerated in practice. Furthermore, alloying of the materials with other substances in which thorough intermixing of the individual components is achieved, is not at all possible with the conventionally known process.  
  A conventional process also known in the art uses a support in the form of symmetrical rotational crucible which is driven at uniform rotational velocity about an inclined axis. Through such an arrangement, however, it is not possible to obtain optimum purification and alloying of materials within a reasonable time interval, since thorough intermixing does not take place.  
  Accordingly, it is an object of the present invention to provide an arrangement for purifying metals, as well as forming alloys of metals.  
  Another object of the present invention is to provide the aforementioned arrangement in which the metals remain continuously under the influence of a source of energy for melting the metals while undergoing purifcation or alloying.  
  A still further object of the present invention is to provide an arrangement, as described, in which quanti ties of molten metals are purified and/or alloyed while they are not moved out of the path of a source of energy used for melting the materials.  
  Still another object of the present invention is to provide an arrangement which is simple in design and may be readily constructed in an economical manner.  
 SUMMARY OF THE INVENTION The objects of the present inventionare achieved by providing an arrangement in which the support for the molten metallic materials is moved or displaced so that the metallic elements in molten state roll on the support while the latter is displaced. Such rolling action executed by the metallic elements causes them to retain their positions in space. Furthermore, in view of the rolling action of the metallic elements, it is possible to continuously bring new surface portions of the metallic elements in contact with the surrounding atmosphere. The metallic elements are held together or retain their shape as a result of their surface tension characteristics. By rolling on the support in this&#39;manner, the metallic balls or droplets have surface portions removed for predetermined time intervals from being in contact with the support. At the same time, the rolling action of the droplets or metallic balls produces simultaneously a mixing process through which the individual metallic components or elements are thoroughly intermixed. Thus, through the rolling action, new volume elements are continuously brought from the region at the surface of the droplets or metallic balls and moved towards the interior thereof. The necessary length of the diffusion path is, hereby, strongly reduced, so that the gas interchange or purification time is significantly shortened. With the rolling and mixing actions the further advantage is realized whereby small quantities of materials may be economically alloyed. Finally, the temperature distribution within the metallic elements is made more optimum as a result of the intermixing processes, so that local overheating is avoided with the accompanying vaporization of alloying elements having low boiling points. Since the metallic elements retain their positions in space, it is not necessary to provide complex regulating and control mechanisms which are usually required for moving the source of energy for heating the metallic elements so that the energy source may follow along with the motion of the metallic elements.  
  The process in accordance with the present invention may be carried out either in vacuum or in the environment of a protective gas. For reinforcing the purification effects, it is desirable to carry out the process under vacuum. Sources of energy used for melting the metallic elements may be in the form of electric arcs plasma beams or similar such means. Electron beams, however, have been found to be particularly advantageous. When using electron beams, it is essential to carry out the process under vacuum, since widening of the electron beams within substantially dense gases results in process difficulties which may even make it impossible to carry out the process. Electron beams, furthermore, possess the characteristic of high energy density, and the electron beams may be easily deflected or controlled so as to be directed onto a predetermined or desired target point or impact point.  
  The rolling motion of the metallic elements on the support may take place in any desired manner. However, it is particularly advantageous when the support executes a periodic oscillation. An arrangement for carrying out the process in accordance with the present invention, has a vacuum chamber, a source of energy and a support for treating or processing the metallic elements. In accordance with the present invention, the support is rotatably suspended and possesses a circularshaped surface on which the metallic elements may roll. The place through the circle of the rolling surface is vertical, and the point of rotation for the displace ment or motion coincides with the center point of the rolling surface. The support, furthermore, can also be in the form of a ring-shaped closed groove having a horizontal axis. Upon rotation of the support about this axis, the molten metallic elements retain their position at the lowest point or location on the groove which is also below the axis of rotation. Upon applying a periodic oscillation to the support, it is sufficient to use a section from this ring-shaped crucible, and to secure this section about the center point. For this purpose, the support is advantageously secured to a rocker arm having a horizontal axis of rotation which passes through the center point of the circular plane of the rolling surface.  
  As a result of the periodic oscillating motion or displacement, improved puification and alloying effects are attained, since the intermixing process is significantly intensified. Molten particles from the interior of the metallic elements are brought to the surface of the elements with greater assurance, so that a gas interchange may take place with the surrounding atmosphere or environment. The charging and removal of the metallic elements from the arrangement is also simplified, since it is only necessary to simply tip the return point of the oscillating displacement about the oscillating axis.  
  The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.  
 BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENTS U Referring to the drawing and in particular to FIG. 1, anelectron beam generator 1 emits a high energy electron beam 3 in fully accelerated form through a pres-&#39; sure step path 2. Through a magnetic deflection system, not shown in the drawing, the electron beam is directed along a slightly curved path, and terminates at the end of the path on a metallic element 4. As shown in the drawing, this metallic element 4 is in the molten state and is held together to retain its shape by its surface tension. The surface tension causes the element 4 to assume the shape of a droplet, for example. The point of impact of the electron beam 3 may also be denoted as the focussed spot 5.  
  The metallic element 4 rests on a support 6 which is in the form of an arc-shaped groove 7. In particular the groove 7 has a circular shape, and the plane of the cir- &#39;cle lies in the plane of the drawing which, at the same time is vertical in practice. The arc-shaped groove 7 is a segmentof a circular-shaped ring crucible having a hollow chamber 8 for retaining a cooling medium as,  
 &#39; in the direction perpendicular to the plane of the drawfor example, water. The support is, furthermore, bent ing, so that a hammock-shaped trough or tub results. This trough or tub encloses the molten metallic element 4 under maintenance of a stable balanced state. The center point of the circle is denoted by 9. This center point 9 serves simultaneously as the axis of rotation or oscillation of the support 6 and a rocker arm10 is pivoted about this axis 9. In conjunction with a drive,  
 not shown in the drawing, the support 6 is to be periodically oscillated or displaced so &#39;that end positions 6a and 6b shown in dotted form result. The frequency of oscillation for displacing the support lies preferably within the range of 0.1 and 1 Hz. The amplitude of oscillation in this embodiment is substantially 60. By carrying out this oscillating motion. the metallic element 4 executes a rolling motion on the inner surface of the support 6. This inner surface is denoted as the rolling surface I! in the drawing. As a result of the rolling of the metallic element, new parts are brought to the upper surface from the rolling surface 11, so that they are continuously subjected to contact with the surrounding atmosphere. Since the lowest point of the support 6 remains at the same position as a result of the geometrical design, the metallic element 4 is forced to remain also in the position shown in the drawing, which is below the axis of rotation 9. With this arrangement the electron beam 3 will continuously be directed onto the metallic element 4. The entire arrangement, furthermore, is surrounded by a vacuum chamber la, which is evacuated by means of vacuum pumps, also not shown in the conventional manner.  
  In FIG. 2, parts which are identical to those used in FIG. 1 are denoted by the same reference numerals. In place of the electron beam generator 1, however, an electric arc electrode 12 is provided. By applying a voltage between the electrode and the support 6 which is in electrical contact with the metallic element 4, an are 13 may be generated between the electrode and the metallic element 4. This electric are 13 may be used for melting and further heating of the metallic element 4. Aside from using an electric arc in FIG. 2, the remaining functions of the arrangement of FIG. 2 are similar to the embodiment of FIG. 1. In FIG. 2, the oscillating motion or displacement is carried out perpendicular to the plane of the drawing.  
  It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of arrangements for melting, purifying and alloying materials, differing from the types described above.  
  While the invention has been illustrated and described as embodied in arrangements for melting, purifying and alloying materials, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.  
 I claim:  
 1. An arrangement for processing metallic materials under vacuum, comprising, in combination, a movable support; a metallic substance on said support; means for applying heat to said metallic substance on said support for maintaining said metallic substance in molten state, said metallic substance assuming a shape determined by the surface tension characteristics of said metallic substance; means for rotatably suspending said support about a predetermined pivot axis, said support 2. The arrangement as defined in claim I wherein said means for rotatably suspending said support com prises a rocker arm suspended from said pivot axis, said pivot axis being horizontal and passing through the center point of said rolling surface.  
 3. The arrangement as defined in claim I wherein said metallic substance is in form of a droplet.  
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