Method of making arc tubes

摘要

A method of making an arc tube chamber (34) intermediate open tubular end portions comprises the steps of: (a) providing a tube (80) of vitreous material; (b) heating a portion of the tube (80) sufficiently to soften it in a predetermined area (88); (c) axially compressing the tube (80) to force the softened material in the heated area (88) radially inward and outward around the circumference of the tube (80) to thereby thicken the tube (80) wall in the heated area; (d) repeating step (b) and step (c) in areas of the tube (80) proximate to the previously thickened tube wall at least one additional time to thereby thicken the wall of the tube (80) over an axial distance approximating the length of the desired chamber (34); (e) heating the thickened wall area (90) of the tube (80); (f) positioning a mold (92,94) having a chamber cavity of a desired shape over the heated thickened wall area (90); (g) internally pressurizing the tube to expand the heated thickened area (90) of the tube (80) against the internal wall of the mold cavity (92,94) to thereby form a chamber (34) in the tube (80); and (h) removing the mold (92,94) from the chamber (34) to thereby provide an arc tube chamber (34) intermediate open tubular end portions. <IMAGE>