Abstract: Blow-molded thermoplastic articles such as bottles are produced from preforms while measuring the pressure in the article and comparing the measured pressure with standard values. Articles having measured pressure values which deviate from standard are rejected.

Abstract: In apparatus for controlling the length of parison portions available for blow molding which includes a carrier supporting a plurality of blow molds, a drive train for the carrier to consecutively position such molds beneath an extruder head and a logic module responsive to a control signal for regulating the length of parison portions protruding beyond the cavity of successively presented molds, the improvement which includes variable speed means responsive to such signal for changing the speed of movement of the carrier to vary the rate at which consecutive molds are presented to the head.

Abstract: The process comprises heating a hollow thermoplastic parison to orientation temperature ranges by selectively applying radiant heat to at least three portions of the parison. The thus irradiated parison is passed to a molding zone, and therein subjected to a pressure differential sufficient to expand the parison into conformity with a molding zone cavity.

Abstract: Method for controlling the length of parison portions available for blow molding which includes use of a carrier supporting a plurality of blow molds, a drive train for the carrier to consecutively position such molds beneath an extruder head and a logic module responsive to a control signal for regulating the length of parison portions protruding beyond the cavity of successively presented molds, the improvement which includes use of variable speed means responsive to such signal for changing the speed of movement of the carrier to vary the rate at which consecutive molds are presented to the head. The method involves varying the speed of movement of the carrier in response to such signal to thereby vary the rate at which molds are presented for receiving consecutive parison portions, and therefore the amount of the length of each such parison portion available to protrude beyond the cavity of a mold.

Abstract: Corrugated plastic tubes simultaneously feeding from a plurality of sources are doffed, stacked in nesting relation and formed into bundles of a predetermined number of tubes in accordance with the present invention. The corrugated plastic tubes are produced in continuous length in separate production lines, cut to predetermined lengths, and fed along predetermined paths to respective doffing stations where the tubes are doffed into a common hopper positioned adjacent the doffing stations. Upon a predetermined number of the tubes being doffed into the hopper and accumulated in stacked and nested relation, the tubes are advanced to a bundling station where strapping machines secure pliable strapping elements around the stacked and nested tubes to form the same into compact bundles. The bundles are then removed from the bundling station ready for shipment or storage.

Abstract: Multiaxially oriented containers are formed from an extruded, molecularly orientable thermoplastic parison having a programmed wall thickness. The parison while at extrusion temperature is sealed at one end and expanded incrementally in a conditioning mold into the shape of a preform which is allowed to set therein for a brief time period in order to develop an outer skin at reduced temperature. The full wall of the variable thickness preform is then reduced in temperature to within the orientation temperature range and the preform then stretched longitudinally and expanded radially in a finishing mold to develop axial and radial orientation while forming the container. Since the thicker portion(s) of the programmed parison do not cool as much in the conditioning mold as do the thinner portion(s) they consequently subsequently stretch to a greater extent, and this phenomenom must be compensated for in the initial programming step.