Manufacture of halogen cycle incandescent lamps

Claim 1

Method of manufacturing a halogen cycle incandescent lamp having a bulb of hard glass and lead-in wires passing thereinto through a pinch seal comprising, in accordance with the invention, the steps of providing a length of hard glass tubing (1); clamping the ends of the hard glass tubing length in clamps (2), heating the tubing intermediate the clamps and drawing apart the hard glass tubing to shape a bulb (5) with a rounded-off bowl (6) and an integrally formed exhaust tube (4); providing a mount comprising one or more individually connectible filaments (7) and two or more lead-in wires (8); said mount with the wires being introduced into the bulb (5) with the lead-in wires extending through the open portion of the tubing forming the bulb at the end remote from the exhaust tube; heating a portion of the bulb through which the mount has been introduced and containing a quantity of about two or more grams of glass substantially uniformly about its circumference to a working temperature at which the glass will soften to a viscosity of approximately 10 +4 poise, said temperature being sufficient to render the glass plastic but below the temperature at which the glass will wet the lead-in wires; pinching the heated glass to surround the lead-in wires mechanically in close engagement to form an initial mechanical connection between the mount and said wires and the thus pinched bulb and to provide a preliminary pinch portion; withdrawing the pinch tool from the pinched region; heating the thus pinched region by heating at least those portions of the pinched glass which are immediately adjacent the wires to liquefaction temperature and fusion with the wires to effect wetting of the glass immediately adjacent the wire and intimate merger of the surface of the wire with the glass to form a vacuum tight fusion seal; then, after the vacuum tight fusion seal is obtained, mold pinching the initially pinched and reheated, fused region in a pinched-mold to mold the pinch region to a desired external shape which is to be retained after the lamp has been made to re-fashion the external shape of the lamp after the heating-to-fusion step; and finishing the lamp by filling the lamp with an inert gas through the exhaust tube (4) and tipping off the exhaust tube.