Dispensing – Processes of dispensing – Molten metal
Utility Patent
1999-06-21
2001-01-02
Kastler, Scott (Department: 1742)
Dispensing
Processes of dispensing
Molten metal
C222S591000, C222S598000
Utility Patent
active
06168053
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to precision pouring of a liquid from a vessel into a container, particularly when the vessel and container are located inside a chamber.
BACKGROUND OF THE INVENTION
In vacuum metallurgy and in many other fields, liquids, such as molten metals and alloys, are often processed inside a chamber containing an atmosphere that may be at, above or below ambient atmospheric pressure. Such processing includes the pouring of a liquid at a pre-determined rate from a vessel, such as a melting furnace, into a container such as a mold. A vessel generally having a pour lip and containing a liquid is tilted to establish a pour stream that is targeted at an opening in the container. The desired pour rate may be fixed, or it may be profiled, meaning that the desired rate varies during the course of the pour. Since the targeted opening is usually fixed and the trajectory of the pour stream changes during the pour, the relative positions of the vessel and container must be controllable to allow the pre-determined flow rate and aim point to be maintained. Where the container is not moved, the horizontal (or X-axis) position of the vessel and its tilt angle measured from the Y-axis (orthogonal to the X-axis) must be adjustable. If it is also desired to simultaneously control the vertical distance of the pour lip above the target opening, the vertical position of the vessel must also be controlled.
A known approach to meeting the above requirements is to mount the vessel on a manipulator, located inside the chamber. However, such a manipulator is difficult to access for maintenance or repair. Moreover, any mechanism so located is likely to be exposed to liquid splash, fume, condensation of volatiles evolved from the liquid, etc., so it is likely to need frequent maintenance or repair. Therefore, it is advantageous that essentially all of the mechanism for moving and tilting the vessel be accessibly located outside of the chamber and sealed such that it is not exposed to the atmosphere inside. The seal system must also maintain the integrity of the atmosphere, allowing gases to leak neither out of nor into the chamber.
A prior art approach that achieves some of the above objectives is to mount the vessel eccentrically on a plate which is supported from the chamber wall and which rotates about the center of a circular peripheral seal. Rotary motion about said center is advantageous because sealing surfaces that were covered by the seal, and therefore protected from contamination prior to such rotation, remain covered and protected during and after rotation. Such protection from contamination such as splash, fume and condensates improves seal life. Rotation about this first axis, which is at a relatively large vertical distance below the vessel pour lip, will move the pour lip primarily in the horizontal direction, as long as the amount of angular motion is kept small. Rotation about a second axis, located closer to the vessel's pour lip than the first axis, tilts the vessel to assist the pouring of molten metal from the vessel.
This approach, however, has its own disadvantages. The requirement that the amount of angular motion about the first axis be kept small, means that for a given amount of traverse motion, a relatively large distance must be maintained between the pour lip and the first axis of rotation. This requirement makes the rotary plate relatively large in diameter. Consequently, relatively large forces are exerted on it when there is a significant differential pressure between the outside and the inside of the chamber. In such a case, which happens commonly, the plate must be built to withstand these large forces. This can make the plate relatively heavy and expensive. These large forces also undesirably increase the loads on the bearings that rotatably connect the plate to the chamber, unless additional compensating measures are taken. Another disadvantage of this approach is that, since the vessel's translation movement is an arc, there will also be some accompanying, coupled vertical movement of the vessel as the plate is rotated to obtain the required horizontal translation. Therefore, the height above the target opening of the vessel and its pour lip change as a function of the translation motion. This height change, being a function of the geometry of the apparatus and the motion around the two axes, is not independently controllable. For precision pouring, it is desirable that the pour lip height be independently controllable.
In the present invention, a combination of rotational movements about two offset axes can be used to achieve a truly horizontal translation of a vessel if such is desired, while a coordinated rotational movement about a third axis can be used to control the tilt angle of the vessel. This combination has the capability of pouring at a controlled rate, while simultaneously directing the pour stream at an aim point. This apparatus can be made more compact than the prior art apparatus just described, while providing equivalent or better functionality. Such compactness minimizes the above disadvantageous aspects of the prior art, while also permitting installation of the present invention on smaller chambers.
Alternatively, the rotations about the three axes may be differently coordinated, to further provide an independently controllable vertical component to the motion of the vessel. In this case, not only can the pour rate be maintained at a pre-selected value and the pour stream directed at the aim point as described above, but the vertical position of the pour lip can also be independently controlled.
SUMMARY OF THE INVENTION
The present invention, in one aspect, is a method for pouring liquid from a vessel by a fluid stream that flows from the vessel to a predetermined location or aim point. Three rotational elements are established to provide for two-dimensional movement of the vessel simultaneously with independent controllable tilt of the vessel. The first element rotates about a first axis of rotation. The second element rotates about a second axis of rotation. Relative to the first element, the rotational axis of the second element is located within the periphery of the first element, with its axis of rotation offset from and substantially parallel to the axis of rotation for the first element. The third element rotates about a third axis of rotation. Relative to the second element, the rotational axis of the third element is located within the periphery of the second element, with its axis of rotation substantially parallel to and offset from the axis of the second element. The vessel is connected to the third element. Consequently, rotation of the first, second and third elements about the first, second and third axes of rotation, respectively, will translate and rotate the vessel to accomplish pouring of the liquid from the vessel by a fluid stream to a predetermined location. If the offset distance between the axes of rotation for the first and second elements and the offset distance between the axes of rotation for the second and third elements are equal, then equal counter-rotation of the first and second elements will translate the vessel a horizontal distance of up to four times the equal offset distance. With equal offset distances and without equal counter-rotation, the trajectory of the two dimensional translation can be anywhere within a circle centered on the axis of rotation for the first element, and having a diameter equal to four times the equal offset distance.
In another aspect, the present invention is apparatus for pouring a liquid from a vessel by using a positioning system that has three rotatable elements. The first element has an opening and is connected to a fixed supporting structure in such manner that it is rotatable about an axis of rotation relative to the fixed supporting structure. The second element has an opening and is connected to the first element in such manner that it is rotatable about a second axis of rotation relative to the first element. The secon
Consarc Corporation
Kastler Scott
Seidel, Gonda, Lavorgna & Monaco, PC.
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