Apparatus for preparing heat-set plastic hollow vessel

An apparatus for preparing a drawing heat-set plastic hollow vessel, which comprises

• a mandrel for supporting a preform composed of a plastic material and a hollow vessel formed from said preform,
• a supply zone for mounting the preform on said mandrel,
• a preheating zone comprising a turret having along the periphery thereof a plurality of supporting seats for supporting said mandrel and a heating mechanism for heating the preform on the mandrel,
• a blow-forming and heat-setting zone comprising a plurality of openable and closable blow-forming and heat-setting molds and a rotary member having along the periphery thereof mandral supporting members corresponding to said molds,
• a delivery zone for delivering the mandrel having the preheated preform mounted thereon, which comes from the preheating zone, to the blow-forming and heat-setting zone,
• a withdrawal zone for withdrawing the mandrel having a blow-formed and heat-set vessel mounted thereon from the blow-forming and heat-setting zone, and
• an endless delivery passage for passing the mandrel through said supply zone, preheating zone, delivery zone, blow-forming and heat-setting zone and withdrawal zone in the recited order.
• the improvement wherein the
• blow-forming and heat-setting zone comprises a mold including means for heating said mold at a heat-setting temperature through the entire course of rotation,
• a mold opening and closing mechanism for closing the mold after the mold has passed through the delivery zone and opening the mold when the mold arrives at the withdrawal zone,
• a hollow drawing rod arranged concentrically with the mandrel, which is capable of reciprocating relatively to the preform,
• a first gas passage laid out between the periphery of the drawing rod and the mandrel and leading to the interior of the perform,
• a second gas passage arranged in the interior of the drawing rod and leading to the interior of the preform through openings distributed int the length direction of the drawing rod,
• a high-pressure hot air supply mechanism as a fluid for blow-drawing the preform
• a hot air discharge mechanism, leading to the first gas passage through an opening-closing valve or a changeover valve,
• a low-pressure cold air supply mechanism leading to the second gas passage through an opening-closing valve, and
• an opening-closing control valve for connecting the first gas passage to the high-pressure hot air supply mechanism synchronously with insertion of the preform into the drawing rod to effect the draw-blow forming of the preform and simultaneously confining hot air in the formed vessel to effect the heat-setting of the formed vessel and for connecting the first gas passage to the hot air discharge mechanism after the heat-setting and connecting the second gas passage to the cold air supply mechanism to effect discharge of hot air and cooling of the vessel.