Blow molding process and apparatus for producing hollow plastic articles

A blow molding process for producing hollow plastic articles comprising:

• providing an extrusion machine having a die defining a downwardly extending annular melt passage in combination with air blowing means and a mold having a cooling means below the die including two mold halves defining a cavity, and
• performing in each blow molding run the steps of:
• plasticizing and metering an engineering plastic material within the extrusion machine;
• extruding the plasticized and metered material having a hollow form through the die annular passage toward the mold, when the mold is opened;
• and
• preblowing air at a low pressure from the die into the interior of the extruded hollow material during the extrusion step, to thereby produce a parison having a longitudinal hollow form to be partially received in the mold and molded to form the article within the cavity defined by said mold halves,
• wherein the extrusion machine is activated so as to elevate an extrusion speed from zero up to a level near a predetermined full speed .alpha. immediately after the commencement of the extruding step,
• wherein both the extrusion and preblowing steps for preparing said parison are commenced concurrently, and
• wherein a material remaining in the die is integrated with an upstream portion of a downstream parison prepared in a preceding blow molding, said portion having a closed and free lower end.