Abstract Hollow cylinders and tubes are made from vitreous silica by placing granular or powdered quartz or silica starting material on a granular bedding layer in a hollow form revolving about its axis and, as the rotation of the hollow form continues, melting by means of an electrical power source, and solidifying the starting material. An electrically heated hollow cylinder of carbonaceous material is disposed in the hollow form and the apertures thereof are hermetically closed with covers after the starting material has been put in. The sealed inner chamber thus formed is slowly evacuated with a vacuum to a pressure ranging from 10 to 0.0001 mm Hg. The starting material is slowly heated to the melting point while sustaining this pressure. After complete melting, the electric power source is shut off and the fused article is cooled while rotation continues. Thereafter, the vacuum pump is shut off and the inner chamber is aired before removing the cover. Lastly, the vitreous silica hollow cylinder which is still at temperatures between room temperature and 1400*C., is removed from the hollow form. Apparatus for making hollow cylinders from vitreous silica via the above-described process includes horizontally disposed, rotatable hollow form means adapted to be hermetically sealed with a cover means having a vacuum connection connected to vacuum means. Crucible means are positioned within the form means and a graphite vacuum baffle means extends into the hollow form means and the crucible means. A filling of refractory thermal insulation material is between the crucible means and the hollow form means.
APPARATUS FOR MAKING HOLLOW CYLINDERS FROM VITREOUS SILICA COMPRISING HORIZONTALLY DISPOSED, ROTATABLE HOLLOW FORM MEANS ADAPTED TO BE HERMETICALLY SEALED WITH COVER MEANS HAVING A VACUUM CONNECTION CONNECTED TO VACUUM MEANS, CRUCIBLE MEANS POSITIONED WITHIN SAID FORM MEANS, GRAPHITE VACUUM BAFFLE MEANS CARRIED BY SAID VACUUM CONNECTION EXTENDING INTO THEHOLLOW FORM MEANS AND THE CRUCIBLE MEANS A FILLING OF REFRACTORY THERMAL INSULATION MATERIAL BETWEEN THE CRUCIBLE MEANS AND THE HOLLOW FORM MEANS, AND ELECTRICAL ENERGY MEANS CONNECTED TO SAID CRUCIBLE MEANS.
Claim 2
Dependent Claim
81 words
APPARATUS FOR MAKING HOLLOW CYLINDERS FROM VITREOUS SILICA COMPRISING HORIZONTALLY DISPOSED, ROTATABLE HOLLOW FORM MEANS ADAPTED TO BE HERMETICALLY SEALED WITH COVER MEANS HAVING A VACUUM CONNECTION CONNECTED TO VACUUM MEANS, CRUCIBLE MEANS POSITIONED WITHIN SAID FORM MEANS, GRAPHITE VACUUM BAFFLE MEANS CARRIED BY SAID VACUUM CONNECTION EXTENDING INTO THEHOLLOW FORM MEANS AND THE CRUCIBLE MEANS A FILLING OF REFRACTORY THERMAL INSULATION MATERIAL BETWEEN THE CRUCIBLE MEANS AND THE HOLLOW FORM MEANS, AND ELECTRICAL ENERGY MEANS CONNECTED TO SAID CRUCIBLE MEANS.
Claim 3
Dependent Claim
24 words
Apparatus of claim 1 wherein the hollow form means comprises a double-walled metal structure having means for passing a coolant between said double walls.
Claim 4
Dependent Claim
29 words
Apparatus of claim 1 wherein the hollow form means comprises an electrically insulating material and tubular induction coil means through which coolant can flow surrounding said hollow form means.
Claim 5
Dependent Claim
92 words
Apparatus of claim 1 wherein the crucible means has an open end facing the cover means and is adapted to receive respective layers of bedding material and starting material therein, graphite pot means horizontally positioned in front of the open end of the crucible means, said pot means having a bottom with an aperture adjacent the open end of said crucible meaNs, the remaining portion of said bottom being equal in radial width to at least the sum of the bulk depths of the bedding and starting materials in the crucible means.
Claim 6
Dependent Claim
37 words
Apparatus of claim 4 wherein the vacuum baffle means extends into the graphite pot means with its forward end not extending beyond the surface of the bottom of the graphite pot means that faces the crucible means.