Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B7/00—Mixing; Kneading
  • B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
  • B29B7/34—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices
  • B29B7/38—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary
  • B29B7/46—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft
  • B29B7/48—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft with intermeshing devices, e.g. screws
  • B29B7/488—Parts, e.g. casings, sealings; Accessories, e.g. flow controlling or throttling devices
  • B29B7/489—Screws
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/251—Design of extruder parts, e.g. by modelling based on mathematical theories or experiments
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/251—Design of extruder parts, e.g. by modelling based on mathematical theories or experiments
  • B29C48/2517—Design of extruder parts, e.g. by modelling based on mathematical theories or experiments of intermeshing screws
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
  • B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
  • B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
  • B29C48/402—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders the screws having intermeshing parts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/50—Details of extruders
  • B29C48/505—Screws
  • B29C48/59—Screws characterised by details of the thread, i.e. the shape of a single thread of the material-feeding screw
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/50—Details of extruders
  • B29C48/505—Screws
  • B29C48/64—Screws with two or more threads
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/92—Measuring, controlling or regulating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92009—Measured parameter
  • B29C2948/92019—Pressure
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92009—Measured parameter
  • B29C2948/92038—Torque
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92009—Measured parameter
  • B29C2948/92085—Velocity
  • B29C2948/92095—Angular velocity
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92009—Measured parameter
  • B29C2948/92209—Temperature
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92323—Location or phase of measurement
  • B29C2948/92361—Extrusion unit
  • B29C2948/9238—Feeding, melting, plasticising or pumping zones, e.g. the melt itself
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92323—Location or phase of measurement
  • B29C2948/92361—Extrusion unit
  • B29C2948/9238—Feeding, melting, plasticising or pumping zones, e.g. the melt itself
  • B29C2948/9239—Screw or gear
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2948/00—Indexing scheme relating to extrusion moulding
  • B29C2948/92—Measuring, controlling or regulating
  • B29C2948/92323—Location or phase of measurement
  • B29C2948/92485—Start-up, shut-down or parameter setting phase; Emergency shut-down; Material change; Test or laboratory equipment or studies
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
  • B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
  • B29C48/405—Intermeshing co-rotating screws

Definitions

• the present invention relates to the technical field of screw extruders and to the optimization of screw extruders and extrusion processes.
• the present invention is a method for optimizing the geometry of screw extruders and for optimizing extrusion processes.
• the present invention furthermore relates to a process for the production of screw extruders.
• the subject matter of the present invention is furthermore a computer system and a computer program product with which the methods according to the invention can be carried out.
• Screw extruders are used, for example, in the production, processing and processing of plastics and foods.
• the tightly meshing twin-screw shaft with corotating shafts has a dominant role among the extruders.
• a significant advantage of the tightly meshing co-rotating screw, in contrast to the single-shaft machines, is that the threads scrape exactly to the necessary games and thus clean each other. Screw extruders are described in detail in the following publication [1]: K.
• the aim of the flow simulations is to gain a deeper understanding of the flow processes taking place in the extruder in order to ensure a safe and economical extruder design together with a few experiments.
• Simulations should also serve to capture processes that are difficult or impossible to measure in an experiment.
• a flow simulation provides local information about pressure, velocity, and temperature throughout the computational domain.
• the calculation of gradients gives additional information about shear rates and heat transfer coefficients.
• the complexity of the models can be gradually increased. This enables statements as to which process variables are decisive for product quality. By varying the operating conditions, extrusion processes can be optimized.
• the object of the prior art to provide a more efficient method for optimizing screw extruders and / or extrusion methods.
• the sought-after method should in particular be suitable for identifying also optimized geometries for extruders.
• the object is also to provide a method for producing optimized screw extruders.
• this object is achieved by decoupling the simulation calculations from the concrete optimization.
• a multiplicity of simulation calculations are first carried out in a previously defined parameter space.
• the results of the simulation calculations are used to generate a data-based model for this parameter space.
• the data-based model describes the defined parameter space and provides forecast values for all stored value combinations for the stored parameters.
• the results of the simulation calculations for a variety of different issues are available and no further simulation calculations must be performed to answer a specific question.
• predictions for specific questions can be made in a much shorter time than would be needed to perform a simulation calculation.
• the data-based model can also be used to optimize parameter values for extruders and / or extrusion processes.
• the time-consuming individual simulation for a specific problem is thus replaced by an overall model that only has to be generated once.
• the high computational effort is unique and can be automated as far as possible. It is crucial that the results of the simulations are stored in a form - in the form of the data-based model - in which they are available for later questions.
• a first subject of the present invention is thus a method for producing a prediction tool for screw extruders and / or extrusion methods, comprising at least the following steps
• steps (a) to (e) of the process according to the invention are preferably carried out in the order indicated.
• step (a) of the method according to the invention a parameter space is determined. Initially, the parameters required for the simulation of extrusion processes are defined. Three groups of parameter sets can be distinguished: Parameter for describing the Geometry of screw extruders, parameters for writing the extruded material and process parameters.
• Appendix 1 is part of the present application.
• the cross-sectional profiles (profiles according to section perpendicular to the axis of rotation) of a pair of exactly scraping screw extruders can be described by circular arcs.
• the profiles are defined by specifying the centers, radii and angles of the arcs forming them exactly.
• the further parameters for describing the geometry of pairs exactly abschabender screw extruder can be set, such. the slope in a threaded element.
• the indication of the games (game between snail and housing, game between the snails) may be required.
• the geometries of the screws are precisely defined.
• the screws do not necessarily have to be defined as parameters by the above-described coordinates and sizes of circular arcs, but for example, derived quantities can also be used for their description.
• derived quantities are used as descriptors (parameters) of which a real physical influence is to be expected in reality.
• the width of the crest with which the worm scraps the housing can be specified.
• the width of the comb has an influence on the entry of energy into the conveyed material and is therefore an important parameter for characterizing a screw extruder.
• Parameters that characterize the material to be conveyed include density, heat capacity, thermal conductivity, viscosity and others. These parameters for the extruded good are often dependent on process parameter values. For example, the viscosity is dependent on the processing temperature.
• Process parameters include pressure, temperature, screw extruder speed, shaft torque and others.
• the parameter space is defined. This means that the value ranges for the respective parameters are determined, which are to be used as the basis for the simulations. For example, the range of values for the Initial Temperature on Extrusion parameter could be set to 0 ° C to 500 ° C.
• step (b) of the method according to the invention a selection of representative value combinations takes place within the parameter space.
• Representative value combinations are value combinations that describe the parameter space as extensively as possible and cover as many different areas of the parameter space as possible. The goal is to find combinations of values that describe the parameter space so well that the data-based model in which it exists Input value combinations (together with the results of the simulation calculations), can also make predictions for other values.
• experimental design planning based on statistical experimental design such as Placket-Burmann test plans, central composite plans, Box Behnken test plans, D-optimal plans, Balanced block diagrams, methods according to Shainin or Taguchi and others.
• Methods for experimental design are i.a. described in: Hans Bendemer, Optimum Experimental Design, series German paperbacks, DTB, Volume 23 (ISBN 3-87144-278-X) or Wilhelm Kleppmann, Paperback Experimental design, optimize products and processes, 2nd ed. (ISBN 3-446-21615 -4).
• step (d) it is possible that at a later point in time the method according to the invention shows that the selected value combinations do not adequately describe the parameter space (see step (d)). In this case, it may be necessary to select different and / or further value combinations (see step (e)).
• step (c) of the method according to the invention simulation calculations are carried out for the selected value combinations.
• Various selected scenarios are calculated and simulated as to how different screw extruders behave under different process parameters and / or possibly using different materials (extruded material).
• the three-dimensional helical contour must be in a form that allows for mathematical calculations by means of a computer.
• the virtual representation of a screw in a computer advantageously takes place as described in [1] on pages 149 to 150 in the form of a so-called computing grid.
• the construction of pairs exactly abschabenden screws in the computer initially by determining their cross-sectional profiles (hereinafter also referred to as short profiles), ie by fixing the generating and generated screw profile.
• the profiles are preferably determined by specifying the centers, radii and angles of the circular arcs.
• the basic principles listed in Annex 1 and the design specification listed in Annex 1 or a design specification derived therefrom apply.
• the profile is then continued into the third dimension, in the direction of the axis of rotation.
• a model of a conveying element is produced, for example, in that the profile is helically rotated in the axial direction.
• a model of a kneading element is for example generated by the profile is continued in sections in the axial direction, wherein the sections are offset from each other, so that staggered discs arise.
• the representation of the screw extruder in the computer takes place in the form of computer grids.
• the volume between the inner surface of the housing and the surfaces of a screw extruder is crosslinked with a computational grid consisting of polyhedra such as tetrahedra or hexahedra (see, e.g., [1]).
• the computational grid as well as the stock data of the extruder and the operating data of the screw machine in which the screw extruders and the extruder are used, are input in a flow simulation program and the flow conditions are simulated (see, e.g., [1]).
• the results of the flow simulations are available, for example, in the form of flow, pressure and / or temperature fields (see [1] pages 147 to 168). As described in [1] on the pages mentioned above, the flow simulations can be used to determine delivery and performance characteristics. From the simulation results, according to the invention, result parameters are determined which can be related to the value combinations used in each case. Preferably, axle sections and / or slopes of the straight line (pressure difference as a function of the volume flow, power as a function of the volume flow) are calculated from the delivery and performance characteristics (see [1] page 158) and used as result indicators.
• a data-based model is created (step d).
• Such a model should relate value combinations of input variables (input parameters) with the corresponding key performance indicators (output parameters).
• the model is referred to as a data-based model because the model makes these relationships based on existing data (value combinations, performance measures) without the need for real physical relationships between the data and / or input.
• data-based models are, for example: linear and Nonlinear regression models (see eg Hastie, Tibshirani, Friedman: The Elements of Statistical Learning, Springer, 2001), linear approximation methods, artificial neural networks (eg perceptron, recurrent nets) (see eg Andreas Zell: Simulation of neural networks, ISBN 3-486- 24350-0 or Raül Rojas: Theory of Neural Networks ISBN 3-540-56353-9 or MacKay, David JC (September 2003) Information Theory, Inference and Learning Algorithms Cambridge: Cambridge University Press ISBN 0-521-64298 -1), support vector machines (see, eg, B.
• a hybrid model is used.
• All model types contain parameters that are determined using the generated simulation data (training) so that the input-output behavior of the model is optimal in a defined sense.
• step (d) the evaluation of the model quality takes place.
• This can be done, for example, by validation data by checking prediction reliability (see, e.g., Chiles, J.-P. and P. Delfmer (1999) Geostatistics, Modeling Spatial Uncertainty, Wiley Series in Probability and Statistics).
• prediction reliability see, e.g., Chiles, J.-P. and P. Delfmer (1999) Geostatistics, Modeling Spatial Uncertainty, Wiley Series in Probability and Statistics.
• a plausibility check of the dependencies in different areas of the parameter space is carried out using prior knowledge.
• value combinations are preferably used for which simulation calculations were carried out, but which were not used to generate the data-based model (validation data).
• the extent to which the data-driven model can also predict the results of "unknown" scenarios is determined by determining the required model quality, for example the maximum deviation between the calculated simulation result and the model predicted model result. In the modeling of extrusion processes, a maximum deviation of 5%, preferably 2%, has proven to be sufficient model quality.
• the parameter space is redetermined according to the invention and / or other and / or further value combinations are selected which describe the parameter space.
• the repetition of one or more of the steps (a) to (e) is optionally carried out in step (e) until the result parameters can be calculated with sufficient accuracy using the data-based model.
• the result of the described method according to the invention is an optimized data-based model that can be used as a prognosis tool.
• the forecasting tool may be stored as program code on a machine-readable medium such as e.g. a floppy disk, a CD, a DVD, a hard disk, a memory stick or the like.
• the prediction tool located on the machine-readable data carrier can be converted into a
• Memory of a computer to be read.
• a user can operate the prediction tool, i.
• the user is supported by a graphical user interface. It is also possible to realize the prognosis tool as a microchip, which can be equipped with a suitable periphery (input and output)
• Output devices is operated analogous to the program read in the computer.
• the subject matter of the present invention is also a prognosis tool for screw extruders and / or extrusion methods, which has been produced in accordance with the described method for producing the prognosis tool.
• the forecasting tool can be used to calculate the behavior of new or modified extruder screw extruders.
• the forecasting tool can be used to determine the effect of changing process parameter values on the material being extruded.
• Another object of the present invention is thus a method for predicting the behavior of screw extruders in the extrusion of an extrusion material. This procedure includes at least the following steps:
• steps (I) to (IV) of the process according to the invention are preferably carried out in the order indicated.
• step (I) The creation of the data-based model in step (I) is carried out as described above for the method for creating a prediction tool for screw extruders and / or extrusion methods.
• step (II) the values are entered which describe the scenario for which a prediction is to be achieved. These are the values for the geometry of the screw extruders, the values that characterize the extruded material and the values that define the extrusion process.
• the input is usually made with a mouse and / or a keyboard on a computer system on which the forecasting tool can be executed as a software program.
• step (III) the calculation of result key figures takes place by means of the data-based model. This calculation is usually done in a fraction of the time necessary for a single simulation.
• results are output.
• Results can be the calculated earnings figures themselves. These can be displayed as values on a computer screen. You can also display values or quantities that are derived from the key performance indicators. The presentation of results preferably takes place by means of graphics and / or color coding.
• Another object of the present invention is thus a method for optimizing the geometry of screw extruders and / or extrusion processes.
• This procedure includes at least the following steps:
• steps (A) to (D) of the process according to the invention are preferably carried out in the order indicated.
• step (A) The creation of the data-based model in step (A) is carried out as described above for the method for creating a prediction tool for screw extruders and / or extrusion methods.
• step (B) the target profile for the screw extruder and / or the extrusion process is set.
• the determination of the target profile includes the creation of rules for all result key figures (output), which should be fulfilled by the desired value combinations (input). It is possible, for example, to set a maximum temperature increase of the extruded product or a minimum pressure build-up which is required to convey the extruded material through the extruder.
• step (C) The search for those value combinations that meet or come closest to the given target profile is done in step (C) using the data-based model.
• the result key figures (output parameters) can be calculated for a large number of value combinations (input parameters) in a very short time, so that a targeted variation of the values for the input parameters and comparison of the values for the output parameters with the target profile to the required input parameters leads that meet the target profile or come closest to it.
• This search for the "optimal" value combinations to achieve a given profile can be supported by known optimization methods such as Monte Carlo methods, evolutionary optimization (genetic algorithms), simulated annealing, etc. An overview of optimization methods, for example, is provided by M. Berthold et al., Intelligent Data Analysis, Springer, Heidelberg 1999.
• step (D) the output of the value combinations that meet and / or come closest to the specified target profile takes place.
• the output of the calculated result parameters and the deviation of the calculated result parameters from the target profile are preferably also carried out.
• the output may be in the form of numbers and / or graphics on a computer screen or printer.
• the forecasting tool can also be used in the production of new screw extruders.
• a further subject of the present invention is therefore a process for the production of screw extruders, comprising at least the following steps:
• step (iv) output and / or storage of the value combinations determined in step (iii), (v) preparation of screw extruders on the basis of those determined in step (iii)
• steps (i) to (v) of the process according to the invention are preferably carried out in the order given.
• Steps (i) to (iii) correspond to steps (A) to (C) of the process for optimizing the geometry of screw extruders and / or extrusion processes. Accordingly, a geometry of the screw extruder optimized for a given application is determined. This computer calculated geometry is then used to create a real screw extruder (step (v)). Preferably, the geometry data of the screw extruders are converted into a format which can be fed directly to a CNC machine tool (numerical control CNC) for generating the screw elements. Such formats are known to the person skilled in the art. After the geometries have been produced in the manner described, the screw extruders can be used e.g.
• screw extruders are steels, in particular nitriding steels, chrome, tool and stainless steels, powder metallurgically produced metallic composites based on iron, nickel or cobalt, engineering ceramic materials such as e.g. Zirconia or silicon carbide.
• All of the methods according to the invention listed here are preferably carried out on a computer.
• the subject matter of the present invention is also a computer system for carrying out one of the methods according to the invention.
• another object of the present invention is a Computer program product with program code means for carrying out one of the inventive methods on a computer.
• Example 1 Creation of a prediction tool for a double-flighted screw element with Erdmenger screw profile
• the present example describes a method of making a prediction tool for screw extruders and / or extrusion processes, comprising the following steps
• the geometry of a conveyor element with a Erdmenger screw profile is clearly defined by the specification of 6 geometric parameters. These 6 parameters are the number of gears, the housing diameter, the center distance, the play between the worm and the housing, the play between the two worms and the incline. In order to reduce the number of parameters and to obtain a universally valid representation, it is expedient to introduce dimensionless geometrical parameters. As a reference, the case diameter is chosen. It follows that by specifying 5 dimensionless geometric parameters, the geometry of a conveying element with a Erdmenger- screw profile is clearly defined.
• FIG. 1a shows the construction of a self-cleaning and tightly meshing Erdmenger screw profile.
• a Erdmenger screw profile has two symmetry axes, which intersect at an angle of 90 ° on. It is therefore sufficient to produce one quarter of the screw profile and then obtain the complete screw profile by mirroring at the symmetry axes.
• the circular arcs of the screw profile are characterized by thick, solid lines, which are provided with the respective numbers of circular arcs.
• the centers of the circular arcs are represented by small circles.
• the centers of the circular arcs are connected by thin, solid lines both to the starting point and to the end point of the associated circular arc.
• the straight line FP is represented by a thin, dotted line.
• One quarter of a Erdmenger screw profile results from 2 x 2 circular arcs, which correspond to each other.
• the sum of the radii of two corresponding circular arcs (1 and, 2 and 2 ') is equal to the axial distance.
• the central angles of two corresponding circular arcs are the same size.
• the sum of the central angles 1 and 2 is equal to ⁇ / 4.
• the distance of the straight line FP from the coordinate origin is equal to half the center distance and the slope of this line is -1.
• FIG. 1b shows both the self-cleaning, tightly meshing Erdmenger screw profile according to FIG. 1a and a screw profile derived therefrom with play within an eight-shaped screw housing.
• the screw housing is represented by a thin, dashed line.
• the two holes are characterized by thin, dotted lines.
• the centers of the two housing bores are identical to the two pivot points of the screw profiles and are each marked by a small circle.
• the tightly meshing, self-cleaning screw profiles are characterized by a thick, solid line.
• the snail profiles with games are represented by a thin, solid line.
• the snail profile with games was obtained by the method of the room equidistants.
• FIG. 2 shows 255 value combinations between the dimensionless center distance A and the dimensionless pitch T in the selected parameter space.
• FIG. 3 shows 1015 value combinations between the dimensionless center distance A and the dimensionless pitch T in the selected parameter space.
• value combinations are set here in particular on the edge of the parameter space.
• Data-based models are only very limited extrapolationstemp. It is therefore important to provide the margins of the parameter space with value combinations in order to ensure interpolation up to the edge of the parameter space.
• Key performance indicators can be geometric key figures, for example. Geometric characteristics are, for example, the crest angle of a worm element, the helix angle of a worm element relative to the outer radius, the helix angle of a worm element referred to the core radius, the cross-sectional area of a worm element, the worm surface of a worm element, the housing surface, the sum of worm surface and housing surface, the free cross-sectional area of a screw element (that is, the flow-through cross-sectional area between the screw element and the housing) and the surfaces already mentioned relative to the pitch of a screw element (that is, for example, the screw surface relative to the slope).
• the geometric numbers mentioned are advantageously calculated in a simulation program for generating geometries of screw elements, in particular for generating geometries of conveying elements, kneading elements, mixing elements and transition elements.
• Key performance indicators may be, for example, metrics for assessing the grid quality of a computational grid used to compute the flow processes in a scroll element.
• Key figures for evaluating the grid quality of a computer grid are, for example, scewness, aspect ratio and warpage (see Gambit User's Guide, Fluent Inc., Riverside, NH, USA, 2006).
• the cited grating quality indicators are advantageously calculated in a simulation program for generating grating elements for screw elements, in particular for generating computing grids for conveying elements, kneading elements, mixing elements and transition elements.
• Key performance indicators can be, for example, key figures for characterizing the operating behavior of a screw element.
• the performance of screw elements such as conveying, kneading and mixing elements can be described by a pressure difference throughput and by a power throughput characteristic. To facilitate transferability to different extruder sizes, the sizes of pressure differential, performance and throughput are often used in their dimensionless form.
• the intercept points are labeled AI and A2 ([1], page 133).
• the operating point AI indicates the natural throughput of a screw element.
• the operating point A2 indicates the pressure build-up capacity without throughput.
• the intersection points are denoted by Bl and B2 ([1], page 136).
• the point Bl is the so-called turbine point. If the throughput is greater than Bl, power is delivered to the screw shafts.
• the operating point B2 indicates the power requirement without throughput.
• data-based models from present input and output variables is part of the general state of the art.
• Well-known data-based models include: linear and nonlinear regression models, linear approximation methods, artificial neural networks, support vector machines, hybrid models.
• a hybrid model was used to create a prediction tool for a two-flighted auger element with Erdmenger screw profile.
• FIG. 4 shows the predicted crest angle of a double-flighted delivery element as a function of the dimensionless center distance A (horizontal axis) and the dimensionless incline T (vertical axis).
• FIG. 5 shows the predicted pressure build-up parameter A2 of a two-speed conveying element as a function of the dimensionless center distance A and the dimensionless pitch T.
• steps (b) to (d) were repeated.
• a prediction accuracy of on average 3.22% with a standard deviation of 3.59% is often unacceptable for a design of screw extruders.
• the number of value combinations has been increased to a total of 3358.
• the further value combinations were distributed as evenly as possible in the parameter space, on the other hand, additional value combinations were again set to the edges of the parameter space. It has been dispensed with the possibility to set other combinations of values according to a local deviation size or local gradients of the earnings ratios.
• a prediction accuracy of 1.52% on average with a standard deviation of 1.55% is sufficient for a design of screw extruders.
• Example 2 Creation of a prediction tool for a double-flighted screw element with a reduced comb angle compared to a Erdmenger screw profile
• Rita shredder elements Slug elements with a reduced crest angle, hereafter referred to as Rita shredder elements (Rita-reduced tip angle), have a reduced crest angle compared to the Erdmenger screw profile.
• the relative ridge angle R is defined by the quotient of the ridge angle of the Rita screw profile and the ridge angle of the Erdmenger screw profile, in each case the self-cleaning, closely meshed screw profiles are considered.
• a parameter space of 0 ⁇ R ⁇ 1 is selected.
• the other dimensionless parameters and associated parameter spaces of the Rita screw element correspond to the Erdmenger screw element of Example 1.
• FIG. 6a shows a self-cleaning, tightly meshing Rita screw profile.
• the basic structure of Figure 6a corresponds to that of Figure la.
• a quarter of a Rita screw profile results from 2 x 3 circular arcs, which correspond to each other.
• the dimensionless center distance A 0.8333.
• FIG. 6b shows both the self-cleaning, tightly meshing Rita screw profile according to FIG. 6a and a screw profile derived therefrom with play within an eight-shaped screw housing.
• the construction of FIG. 6b corresponds to FIG. 1b.
• the snail profile with games is obtained via the method of the room equidistants.
• FIG. 7 shows 6005 value combinations between the dimensionless center distance A and the relative comb angle R in the selected parameter space.
• the selection of the value combinations is done with the methods described in Example 1.
• novel screw elements can be seamlessly integrated into a prediction tool for screw extruders and / or extrusion processes.
• the forecasting tool includes both the novel Rita auger element and the Erdmenger auger element.
• it is possible to create a prediction tool that builds only on the 2647 value combinations with a relative ridge angle smaller R l.
• a hybrid model is used to create a prediction tool for a two-flighted screw element with Rita screw profile.
• the generated data-based model allows the prediction of the desired key performance indicators.
• the shaded area indicated at the bottom left in FIGS. 8 and 9 reflects the area in which negative ridge angles are present.
• the prognosis tool allows the determination of a screw element with requirements for, for example, B2 in combination with other requirements for, for example, the crest angle.
• the profiles of a generating and a generated screw profile can always be composed of circular arcs.
• the size of a circular arc is given by the indication of its central angle and its radius.
• the central angle of a circular arc will be referred to briefly as the angle of a circular arc.
• the position of a circular arc can be determined by the position of its center point and by the position of its start or end point, where it is not specified which is the start point and which the end point, since a circular arc starting from the starting point and ending in the end point in a clockwise or can be constructed counterclockwise. Start and end points are therefore interchangeable.
• the basic principle 2 also applies to profiles with a "kink” if the kink is described by a circular arc whose radius is equal to zero.
• the "size of the bend" is given by the corresponding angle of the circular arc with the radius 0, i.e. with a kink a transition of a first circular arc takes place
• a zero radius arc is treated as a circular arc whose radius is equal to eps, where eps is a very small positive real number that tends to 0 (eps "1, eps -> 0).
• the directions in which the end points of an arc of the generating screw profile lie from the center of the circular arc are in each case opposite to the directions in which the end points of the corresponding arc of the generated screw profile lie from the center of the arc of the generated screw profile,
• the center of a circular arc of the generating screw profile has a distance to the center of a corresponding circular arc of the generated screw profile which corresponds to the center distance
• the connecting line between the center of an arc-generating screw profile and the center of the corresponding arc of the generated screw profile is parallel to the connecting line between the point of rotation of the generating screw profile and the point of rotation of the generated screw profile,
• the profiles are preferably in one plane.
• the axis of rotation of the generating screw profile and the axis of rotation of the generated screw profile are each perpendicular to said plane, wherein the intersections of the axes of rotation with said plane are referred to as fulcrums.
• the distance of the pivot points from each other is referred to as the center distance a.
• ⁇ is the number of cycles ( ⁇ ⁇ 3.14159).
• a number n of circular arcs is chosen to form the generating screw profile, where n is an integer greater than or equal to one.
• ra can assume a value that is greater than 0 (ra> 0) and less than or equal to the axial distance (ra ⁇ a).
• An inner radius ri is chosen, where ri can assume a value greater than or equal to 0 (ri> 0) and less than or equal to ra (ri ⁇ ra).
• n-1 circular arcs are defined by the selectable angles ⁇ _1, a_2, a_ (n-l) and the selectable radii r_l, r_2, r_ (n-l), the angles in
• Radians are greater than or equal to 0 and less than or equal to 2 ⁇ and the radii are greater than or equal to 0 and less than or equal to the axial distance a,
• a circular arc whose radius is 0 is preferably treated like a circular arc whose radius is equal to eps, where eps is a very small positive real number that tends towards 0 (eps "l, eps-> 0), o each of the circular arcs lies within or on the boundaries of a circular ring with the outer radius ra and the inner radius ri, whose center lies on the pivot point of the generating screw profile,
• n 'of circular arcs forming the generated screw profile their angles ⁇ , ⁇ _2', ..., a n 'and their radii r_l', r_2 ', .. *, r_n' are as follows:
• the center of the i'th arc of the generated screw profile has a distance from the center of the i-th arc of the generating screw profile, which is equal to the center distance a,
• the midpoint of the i'th arc of the generated screw profile has a distance from the fulcrum of the generated screw profile, which corresponds to the distance of the center of the i-th arc of the generating screw profile from the fulcrum of the generating screw profile,
• a starting point of the i'th arc of the generated screw profile is in a direction with respect to the center of the i'-th arc of the profile of the generated screw profile, which is opposite to the direction in which a starting point of the i-th arc of the profile of generating screw profile with respect to the center of the i-th arc of the generating screw profile,
• the construction process can be carried out solely with an angle ruler and compass on paper.
• the tangential transition between the ith and the (i + l) -th circular arc of the profile of a screw element is constructed by making a circle of radius r_ (i + 1) around the end point of the ith arc, and the point of intersection of this circle closer to the pivot point of the screw element with the straight line defined by the center point and the end point of the i-th circular arc is the midpoint of the (i + l) -th circular arc.
• a conveyor element is known to be characterized by (see, for example, [1], pages 227-248), that the screw profile is continuously helically twisted and continued in the axial direction.
• the conveying element can be right- or left-handed.
• the slope of the conveyor element is preferably in the range of 0.1 times to 10 times the axial distance, wherein the slope is understood to mean the axial length required for a complete rotation of the screw profile, and the axial length of a conveyor element is preferably in Range of 0.1 times to 10 times the center distance.
• a kneading element is known to be characterized by (see, for example, [1], pages 227-248), that the screw profile is continued in the axial direction in the form of kneading disks.
• the arrangement of the kneading discs can be right- or left-handed or neutral.
• the axial length of the kneading disks is preferably in the range of 0.05 times to 10 times the center distance.
• the axial distance between two adjacent kneading disks is preferably in the range of 0.002 times to 0.1 times the center distance.
• Mixing elements are known to be formed by (see, for example, [1], pages 227-248) that conveying elements are designed with apertures in the screw flights.
• the mixing elements can be right- or left-handed.
• Their pitch is preferably in the range of 0.1 times to 10 times the axial spacing and the axial length of the elements is preferably in the range of 0.1 to 10 times the axial spacing.
• the openings preferably have the shape of a u- or v-shaped groove, which are preferably arranged counter-conveying or axially parallel.
• transition elements are called screw elements, which allow a continuous transition between two different screw profiles, wherein there is a self-cleaning pair of screw profiles at each point of the transition.
• the various screw profiles may be e.g. have a different number of gears.
• Transition elements can be right- or left-handed.
• Their pitch is preferably in the range of 0, 1 to 10 times the center distance and their axial length is preferably in the range of 0.1 times to 10 times the center distance
• the screw element is in the direction perpendicular to the surfaces of exactly abschabenden profile reduced by half the game between the worm and snail.
• the longitudinal Aquidistante and the Jardinäquidistante particularly preferably the Jardinäquidistante be used.

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• 2009
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