Method for producing profiles made of thermoplastic material
AssigneeTechnoplast Kunststofftechnik GmbH
InventorsMeinhard Schwaiger, Hugo Verniest
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Abstract
The invention relates to a method and the thus required devices for automated process and quality monitoring of an extrusion plant and an integrated closed-loop process control system for timely correction of process parameters as a result of fluctuations in the properties of the raw material or parameter fluctuations of the extrusion system in order to ensure an even quality of the produced profile.
Claims15
A method for producing profiles made of thermoplastic material, preferably PVC, in which plastic granulate or powder is plastified in an extruder and is pressed through an extrusion die in order to produce a profile strand with a predetermined cross section, with automated process and/or quality monitoring being performed in order to ensure even quality of the produced profile, such that measured values on the state of the plastic melt are recorded in the extruder and/or extrusion die and are processed, wherein at least at two measuring points spaced from one another in the direction of flow of the plastic melt one control parameter each is calculated which is obtained from a predetermined function depending on the local pressure of the melt and a parameter representative of the flow speed of the melt in the extrusion die.
An apparatus for the closed-loop control of a plant for producing profiles made of thermoplastic material, preferably PVC, in which plastic granulate or powder is plastified in an extruder and is pressed through an extrusion die in order to produce a profile strand with a predetermined cross section, in which measurement transducers are provided for determining the pressure in the melt in order to determine control parameters which are used for the closed-loop control of the extrusion process, comprising a controller calculating a control parameter at at least two measuring points spaced from one another in the direction of flow of the plastic melt each contro parameter being obtained from a predetermined function depending on the local pressure of the melt and a parameter representative of the flow speed of the melt in the extrusion die.
Dependencies are inferred from the claim text.