US Patent 11427368 Manufacturing method for double walled container

A manufacturing method of double walled container comprises preparing a parison having a rigid outer layer and a flexible inner layer, enclosing the parison within a mold including split mold halves, thereby forming a molded parison including a pre-blow cylindrical section, a pre-blow conical bottom section, a pre-blow bottom projection, and a lower parison excessive burr, blowing gas into an inside of the molded parison, thereby forming a blown parison including a cylindrical section and a bottom section, the bottom section including a bottom projection, and removing the lower parison excessive burr from the blown parison, wherein the flexible inner layer is fixed to the rigid outer layer in the bottom projection.