A method of monitoring stretchability of stretch films in a cast film method includes determining a position of a frost line of a film material, which is solidifying to form a film web, on a casting roller of a film machine, ascertaining a correlation of the determined position of the frost line with at least one target position, and comparing the ascertained correlation to at least one stretchability of the film material, which is assigned to the at least one target position.

A flexible die head for continuously extruding pipe may have a flexible ring mandrel (112). A second, open end (120) of the ring mandrel (112) near the die exit may be continuously and resiliently formed to a non-circular shape whilst extruding the pipe so as to provide an extrudate profile to counter slump in plastic pipe forming. Symmetric and asymmetric shapes may be formed by the ring mandrel (112). The second end (120) may be flexed or otherwise distorted by use of a flexing means (122). The ring mandrel (112) may also be necked in a circumferential portion to order to further improve the forming of non-circular shapes.

A method of manufacturing a mixture PTFE thread using a mixture PTFE powder consisting of PTFE: 73-95 wt %, MoS.sub.2: 3-25 wt %, Al.sub.2O.sub.3: 1-5 wt %, and Al(OH).sub.3: 1-5 wt % comprises heat-retaining step for adding 18-25 wt % kerosene of a solvent to the mixture PTFE powder and keeping it warm at 30-50° C. for 40 to 50 hours, extruding the heat-retained mixture PTFE powder into a rod shape with a circular or elliptical cross section at the cylinder temperature of 70-90° C., rolling the extrusion at 100-150° C. into a 0.3-0.7 mm thick sheet shape, multiple-folding the sheet and passing the sheet through an oven at 250-270° C. at the rate of 10-40 cm/s, and stretching the folded sheet with a stretch ratio of 200-600% in multiple stages after heating the sheet at 450-500° C.

A system and method for reducing draw resonance of plastic material in the molten state, so-called melt, leaving an extrusion group of a plant for the production of plastic film, includes at least one thermostatically-controlled cylinder, having an embracement angle, of the melt on the cylinder, adjustable on the basis of the process rate, i.e. the linear movement speed of the plastic film, and/or on the basis of the temperature measured in the proximity of or in correspondence with the clamping area of the melt in a thermoforming, calibration and cooling group included in the plant and positioned downstream of the system.

A molding apparatus that adsorbs thermoplastic resin extruded in a sheet form from an extruding machine, onto a cavity of a mold, and shapes the thermoplastic resin into a shape according to the cavity is provided. The molding apparatus may include a frame that is positioned on a periphery of the mold and is movable relative to the mold, wherein a suction part for suctioning the thermoplastic resin is provided in a contact surface of the frame to contact the thermoplastic resin, and the suction part is provided in a linear shape along with a longitudinal direction of the frame positioned on the periphery of the mold.

The present invention relates to an extruded expanded thermoplastic polyurethane elastomer bead and a preparation method therefor. The bead consists of components of the following parts by weight: 100 parts by weight of a thermoplastic polyurethane elastomer, 0.01-0.5 parts of a foaming nucleating agent, and 0.01-0.2 parts by weight of an antioxidant. The preparation method comprises: mixing materials, then putting the mixture into an extruder for granulation to produce a particle raw material suitable for foaming, finally, putting the particle into a foam extruder, and die foaming then underwater pelletizing, thus obtaining a product bead. The present invention utilizes an extrusion method to prepare expanded thermoplastic polyurethane beads. Control of the working conditions of the foaming process could lead to acquiring an expanded=bead of a controllable density, the cell density evenly distribute. The overall production process is easy to operate. Without any special limit or requirement placed on the equipment, this method is suitable for industrial continuous production.

A pressure chamber is provided for a blown film extrusion apparatus having (i) a die head for extruding a tubular polymer bubble, and (ii) a cooling assembly down-stream of the die head for receiving the bubble and applying a cooling fluid to the bubble. The pressure chamber includes an upstream end wall sealed around the die head outlet, and extending outward from the seal; a side wall movable between a closed position for controlling air flow from a chamber volume surrounding the bubble to the atmosphere, and an open position for permitting air flow from the chamber volume to the atmosphere. The upstream end wall has an inlet for receiving air from an air supply, and an outlet in fluid communication with the inlet and configured to direct the air into the chamber volume to pressurize the chamber volume when the side wall is in the closed position.

A ram extrusion apparatus including a die having several thermal zones, a hopper for introducing a granular polymer resin to the die, and a ram for moving the granular polymer resin through the thermal zones of the die and out from an outlet end thereof at a temperature above the crystalline melt temperature of the polymer resin. The hopper may be designed to deliver the polymer resin into a resin inlet of the die in a plurality of specifically metered amounts which may vary across a width of the resin inlet end of the die. The apparatus may further include one or more finishing tables positioned after the outlet end of the die for receiving and moving the extruded resin away from the outlet end of the die so that there is no backpressure on the extruded resin, and which provide compression force and even cooling to the extruded resin.

A ram extrusion apparatus including a die having several thermal zones, a hopper for introducing a granular polymer resin to the die, and a ram for moving the granular polymer resin through the thermal zones of the die and out from an outlet end thereof at a temperature above the crystalline melt temperature of the polymer resin. The hopper may be designed to deliver the polymer resin into a resin inlet of the die in a plurality of specifically metered amounts which may vary across a width of the resin inlet end of the die. The apparatus may further include one or more finishing tables positioned after the outlet end of the die for receiving and moving the extruded resin away from the outlet end of the die so that there is no backpressure on the extruded resin, and which provide compression force and even cooling to the extruded resin.

A thermoregulation system of rotating metal cylinders in plants for the extrusion and conversion/transformation of plastic films includes heating elements applied to each rotating cylinder, wherein the heating elements are infrared heating elements, and wherein the rotating cylinder includes a metal tube rotating around a fixed shaft, which is rigidly connected to two side plates.