A method for producing a biaxially oriented tube from thermoplastic material, wherein a tube in preform condition is extruded from thermoplastic material and is subjected to a temperature conditioning. Use is made of an expansion device and of a drawing device which is arranged downstream of the expansion device. The expansion device includes a non-deformable expansion part and a run-on part located upstream of the expansion part and having an upstream sealing member. The expansion device further includes a first gas discharge duct having one or more first inlet ports in the exterior surface of the expansion device, a first inlet port being open or closed or partly closed dependent on whether or not the first inlet port is covered and closed, or partly closed, by the tube.

In a resin-film manufacturing apparatus of an embodiment, when a lip gap control is started, a difference between a state of a target heat bolt (THB) at a start of current control and a state of each of all the heat bolts at a start of last control is obtained, when the difference between the states of THB at the starts of the current and last control is a smallest one, a learning result of THB is set as an initial value of a control condition for THB, and when the difference between the states of THB is not the smallest one, either one of a learning result of the heat bolt of which the difference between the states is smaller than the difference between the states of THB and the learning result of THB is set as the initial value of the control condition for THB.

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.

The invention relates to a calibrating device and to a method for calibrating a film tube. An elastically deformable element (704) is secured to the sleeve (703) such that a fluid, in particular a gas, preferably air, can be introduced or discharged via a fluid connection such that a specific pressure P1 and/or a specific volume V1 is set in an area (708) enclosed by the sleeve and the elastically deformable element at a given temperature. Annular bodies (706) and (707) are arranged within the area (708), and a surface section of each annular body (706), (707) supports a respective region of the elastically deformable element (704). The elastically deformable element (704) regions which are supported by the annular bodies are located in the inlet region (711) and the outlet region (712) of the calibrating device for the film tube (713).

A system and method for extruding film with a thickened profile section. In some embodiments, the film forms bags with integral zipper profiles. Plastic film is extruded to form a tube. During extrusion, each thickened profile section is radiantly cooled in a preferential manner before thinner sections of the film freeze. A freezing control device includes at least one radiant cooling plate that is operatively aligned with a thickened profile section. The device also includes a cooling fluid recirculation system configured to maintain the plate at a temperature below the temperature of the extruded tube. The plate can be adjustably mounted on a base for positioning the plate at the desired orientation for cooling the thickened profile section of the tube.

An apparatus includes an upper lip positioned with respect to an air flow passage. The upper lip is to direct air flow from the air flow passage around a bubble of blown film. The apparatus further includes a Venturi ring movably mounted with respect to the upper lip and adjustable in position with respect to the upper lip. The Venturi ring is to adjustably lock the bubble of blown film.

A method comprises the steps of continuously measuring, proximal a tube extrusion die, a diameter of tubing extruded by the die, to produce a plurality of die-measurement or layflat samples; and continuously measuring, downstream of the tube extrusion die and proximal an accumulation point of flattened tubing, a width of the flattened tubing, to produce a plurality of flat-width samples. A slope value is calculated over a selected interval of the layflat samples and the flat-width samples to determine the stability of the diameter of the tubing and the width of the flattened tubing. A y-intercept value is calculated over the selected interval of the layflat samples and the flat-width samples to determine a forecast trend of the diameter of the tubing and the width of the flattened tubing. When the slope values, y-intercept values, and variances are within selected parameters indicative of a stable operation of the tube extrusion die and the accumulation of flattened tubing, the tube extrusion die is calibrated to produce a selected width of flattened tubing.

A system according to various embodiments can include a source for supplying a material to be treated, an extruder, at least two screws, and a drive coupled to the screws for axially rotating the screws. The extruder includes an inlet for receiving the material, which is fed therein in a controlled manner. The screws are provided within the housing of the extruder. The screws have a plurality of compression and release stages that create mechanical heat which is directly applied to the material to change the mechanical properties of the material thereby facilitating a conversion of a physical state of the material from a non-compactable state to a compactable state as the screws rotate and move the material longitudinally along the screws to produce a final product, for example, a feed tub for use as an animal feed.

A system and method for reducing draw resonance of a plastic material in 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 that is 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.

The invention relates to a calibration device (1) for calibrating a blown film (6), said device comprising; —a tubular region (55) with at least one inner wall (92), through which region the blown film (6) can be passed; —a liquid reservoir which provides a liquid and which is situated above the tubular region (55); an inlet region, in which the liquid can be introduced into the space between the outer wall of the blown film (6) and the inner wall (92) of the tubular region (55); and —a scraper device (117), situated below the tubular region (55), by means of which scraper device at least part of the liquid can be removed from the outer surface. The distance of the liquid-removing regions of the scraper device (117) from the main axis of the blown film (6) can be altered.