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AssigneeThe United States of America as represented by the United States Department of Energy
InventorsDavid K. Mee, Albert E. Stephens
Estimating the term…
The invention is a simple and reliable mechanical arrangement for automatically positioning a thermocouple-carrying rod in a vacuum-furnace assembly of the kind including a casing, a furnace mounted in the casing, and a charge-containing crucible mounted in the furnace for vertical movement between a lower (loading) position and a raised (charge-melting) position. In a preferred embodiment, a welded-diaphragm metal bellows is mounted above the furnace, the upper end of the bellows being fixed against movement and the lower end of the bellows being affixed to support means for a thermocouple-carrying rod which is vertically oriented and extends freely through the furnace lid toward the mouth of the crucible. The support means and rod are mounted for relative vertical movement. Before pumpdown of the furnace, the differential pressure acting on the bellows causes it to contract and lift the thermocouple rod to a position where it will not be contacted by the crucible charge when the crucible is elevated to its raised position. During pumpdown, the bellows expands downward, lowering the thermocouple rod and its support. The bellows expands downward beyond a point where downward movement of the thermocouple rod is arrested by contact with the crucible charge and to a point where the upper end of the thermocouple extends well above the thermocouple support. During subsequent melting of the charge, the thermocouple sinks into the melt to provide an accurate measurement of melt temperatures.
In a vacuum-furnace assembly including a casing, a furnace therein, and a crucible in said furnace, said crucible containing solids to be melted when said casing is evacuated to a low pressure, the improvement comprising:
In a vacuum-furnace assembly including a casing, a furnace therein, and a crucible in said furnace containing solids to be melted when said casing is evacuated to a low pressure, the improvement comprising:
In a vacuum-furnace assembly including a casing containing a solid to be contacted with a sensor when said casing is evacuated to a low pressure, the improvement comprising:
Dependencies are inferred from the claim text.
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No related US applications are recorded in the indexed filing history.
Arrangement of monitoring devices; Arrangement of safety devices: devices for monitoring temperature
Crucible or pot furnaces: adapted for treating the charge in vacuum or special atmosphere
Crucible or pot furnaces: heated electrically, e.g. induction crucible furnaces with or without any other source of heat
Details or accessories of furnaces, kilns, ovens or retorts, in so far
Term ended 6 Jun 2000 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of Invention
This invention relates generally to automatic positioners for transducers or sensors. More particularly, it relates to a mechanical arrangement for automatically lifting and lowering a sheathed thermocouple used to determine melt temperatures in a crucible installed in a vacuum furnace.
2. Problem
FIG. 1 is a schematic diagram of a conventional vacuum-furnace assembly provided with a vertically displaceable sheathed thermocouple of conventional design,
FIG. 2 is a schematic diagram of part of the furnace assembly shown in FIG. 1, as provided with a thermocouple positioner designed in accordance with the invention, and
FIG. 3 is a bottom view taken along line 3--3 of FIG. 2.
The invention is generally applicable to vacuum furnaces and the like. For brevity, it will be described as used in conjunction with a vacuum-furnace assembly of the kind described above and shown in FIG. 1.
Referring to FIG. 2, the novel thermocouple positioner comprises an assembly 35. The assembly includes a tubular housing 37, which is supported by a bracket 39 bolted to a furnace coil support 13. As shown, the housing 37 is positioned just above the furnace lid and is in register with an opening 40 therein, as well as with the interior of the crucible 19. Coaxially mounted in the housing is an evacuated conventional welded-diaphragm metal bellows 41 of the welded-diaphragm type and including welded end caps. The upper end cap of the bellows is affixed to the top end of the housing 37, as by means of a bolt 43 threaded into the cap. The upper end cap is formed with a vertical bore communicating with the interior of the bellows, and a bellows-evacuation tube 45 is fitted in the bore and welded to the cap. Following evacuation of the bellows, the external end of the tube is sealed in any suitable manner. In FIG. 2 the bellows is shown in an extended position, to be described.
The bellows housing 37 is formed with vertically extending opposed slots 47, one of which is in view in FIG. 2. The bottom face of the lower end cap 63 (FIG. 2) for the bellows is affixed to and supports a horizontally disposed plate assembly 46, including plate 49a having the configuration shown in FIG. 3 and a thickness less than the width of slots 47. The end cap is affixed to a central portion 51 of the plate. The portion 51 is formed with webs 53 which extend respectively and freely through the housing slots 47 to support a separable external rectangular platform 49. The platform 49 extends freely about the housing 37. In the preferred embodiment, two similar metal weights 57 (FIG. 2) are mounted on the plate 49, on opposite sides of the housing 37, to damp the retraction of the thermocouples and to promote extension of the bellows under conditions to be described. The weights are adjustably mounted, by means of screws 59 passed through slots 61 (FIG. 3) in the plate, so that the weights may be balanced about the central portion 51 to avoid binding of the bellows in the housing. A skirt assembly (not shown) comprising a carbon disc mounted on an inverted stainless steel cup is attached to depend from the plate assembly 46; this helps to center the bellows in the housing and protect against binding.