Preform preheater

In a reheat-blow molding machine including a reheating section and a gravitational slide coupled to the reheating section for introducing a series of preforms to be blow-molded, the improvement comprising pre-heating apparatus coupled to the gravitational slide for preheating a selected portion of each preform as the preform moves down the gravitational slide, the pre-heating apparatus comprising

• a housing coupled to the gravitational slide, and
• heating elements situated within the housing and directed toward a selected locus of points situated in relation to the gravitational slide to define a path along which the selected portion of each preform travels as the preform moves down the gravitational slide.

Pre-heating apparatus for pre-heating a selected portion of each of a series of preforms prior to re-heating and blow-molding the preform, the preheating apparatus comprising:

• a gravitational slide for transporting the series of preforms downward under the influence of gravity,
• a housing coupled to the slide so that the selected portion of each of the series of preforms is shielded from the general environment, and
• heating elements fixed within the housing so that heat from the heating elements is directed toward the selected portion of each of the series of preforms as the preforms descend down the gravitational slide.

A method for increasing the rate of production of blow-molded articles in a reheat-blow process, the process comprising the steps of reheating preforms to a blow-molding temperature and blowing the reheated preforms within a mold until the preform conforms to the mold interior configuration, the method comprising the steps of:

• preheating a selected portion of each preform prior to the reheating step to generate a temperature gradient between the selected portion and the remainder of the preform, and
• initiating said reheating step while the temperature gradient is still present in the preform.