Blow molding

A blow molding assembly comprising:

• a die;
• a mandrel disposed at least partially inside the die and defining, with the die, an annular gap configured to flow molten resin toward an outlet of the die, thereby forming an extruded parison extending away from the outlet of the die;
• a self-adjusting holder disposed outside the die, the self-adjusting holder comprising three or more spring-loaded fasteners configured to bias the die to center, absent molten resin in the gap, the die with respect to the self-adjusting holder, and the three or more spring-loaded fasteners configured to allow, during extrusion of the molten resin, movement of the die with respect to the holder within a plane that is substantially orthogonal with respect to a longitudinal axis of the mandrel, thereby altering a shape of the annular gap and accommodating pressure differences in the molten resin;
• and
• a plurality of mechanical fasteners extending through a body of the self-adjusting holder, the plurality of mechanical fasteners securing the body of the die holder to a head of the blow molding assembly.

A method comprising:

• obtaining a ring-shaped die holder comprising three or more spring-loaded fasteners positioned around an inner perimeter of the die holder and configured to bias a body inserted through the ring-shaped die holder;
• and
• positioning, the die holder around a die of a molding assembly, the molding assembly comprising the die and a mandrel disposed at least partially inside the die and defining, with the die, an annular gap configured to flow molten resin toward an outlet of the die, thereby forming an extruded parison extending away from the outlet of the die, the positioning comprising securing, with a plurality of mechanical fasteners extending through a body of the ring-shaped die holder, the body of the die holder to a head of the molding assembly;
• wherein the spring-loaded fasteners are configured, after positioning the die holder around the die, to apply pressure to respective positions on an outer surface of the die while permitting movement of the die within a plane that is substantially orthogonal to a longitudinal axis of the mandrel, thereby accommodating pressure variations in the molten resin and maintaining a substantially even thickness of the extruded parison.