QUARTZ LAMP RADIANT OVEN

摘要

A method and apparatus for radiant heating of hollow thermoplastic article preforms to the molecular orientation temperature, radiant energy is both converted to heat at the article surface and penetrates the interior of the article wall and is therein converted to heat. The principle limitation of radiant heating is the capacity of the material to conduct heat away from the surface where extreme temperatures would result in crystallization of the material. To achieve the desired temperature uniformly throughout the article wall, brief periods of intense infrared radiant heating are alternated with brief periods of negligible heating to take advantage of the combined effects of radiant and internal conductive heating. The article preforms are rotatably supported parallel to a plane of quartz lamps so that the combined patterns of radiant emission of all the lamps are distributed in continguous segments over the preform surfaces. The articles are rotated while the quartz lamps are alternately energized with high and low levels of power for presettable periods to produce alternate periods of intense infrared radiant emission and insignificant radiant emission.