US 5,397,514 AGranted

Process for producing flat and annular-cross-section extrudates and device for implementing the process

AssigneeBruckner Maschinenbau Gernot Bruckner GmbH & Co. KG

InventorsJurgen Breil, Martin Haupt

Life of this patent

Estimating the term…

Loading patent…

Abstract

In prior art processes of this kind the actual thickness of the extrudate is measured, compared with a reference thickness and the setting regions of an extrusion plant are controlled dependent upon the degree of difference. In order nevertheless to improve the quality of the extrudate in relation to the desired reference thickness, according to the invention the evolution strategy process is used. An increase in the convergence rate can also be attained by taking into account strategy parameters which can be deterministically or stochastically changed, whereby mixing including fixedly settable strategy parameters is also possible. In particular, knowledge of the process can be involved as qualitative process partial knowledge.

Claims18

Dependent claims

A process for producing flat and annular-cross-section extrudates by means of an extrusion system, the extrusion system having an extrusion nozzle in the form of a wide slit or ring nozzle, and having a plurality of local adjustment zones located offset from a draw-off direction in which actuators are triggered for attaining an extrudate command thickness profile, and wherein the extrudate thickness is detected at positions located offset from the draw-off direction by means of a thickness gauge, said process comprising optimization of an extrudate thickness distribution carried out by minimizing the extrudate thickness deviation from a command thickness profile which is specified transversely to the draw-off direction by means of an evolution strategy method, in which in each case as a consequence of random changes (mutations) in control variables used in the context of a specifiable distribution density function (standard deviation), new control variables for final control elements included in said extrusion system, which affect the thickness distribution, are ascertained in the local control zones, [and]using a preselectable suppression rule (selection) in which a selection of control variables that are improved in view of a specified extrudate command thickness profile is made, triggering the final control elements in local control zones of the extrusion system, in order to carry out a following evolution step, and wherein

the evolution strategy method is adapted to various production conditions or for increasing the convergence, in order to attain an optimized setting of the final control elements in a short time, said evolution strategy method using:
prior process knowledge in the form of a transfer function that reproduces a given dependency of output variables on the control variables, or
automatic adaptive process knowledge about the transfer function between local influence on thickness and actually measured values of the extrudate thickness distribution or both said prior process knowledge and said automatic adaptive process knowledge.

A device for carrying out the process of producing flat and annular cross section extrudates, the device including an extrusion nozzle embodied in the form of a wide-slit nozzle or ring nozzle, a plurality of local setting zones that are offset from a draw-off directions, said zones including actuators for attaining an extrudate command thickness profile, a thickness gauge, and an electronic control unit operated in accordance with an evolution strategy method for optimization of an extrudate thickness distribution for minimizing the extrudate deviation from a command thickness profile,

said electronic control unit including means for operating in accordance with the evolution strategy method so that in each case as a consequence of random changes (mutations) in control variables used in the context of a specifiable distribution density function (standard deviation), new control variables for final control elements included in said device, which affect the thickness distribution, are ascertained in the local setting zones, using a preselectable suppression rule (selection) in which a selection of control variables that are improved in view of a specified extrudate command thickness profile is made and for triggering the final control elements in local setting zones of the extrusion system, in order to carry out a following evolution step, and wherein
the evolution strategy method is adapted to various production conditions or for increasing the rate of convergence, in order to attain an optimized setting of the final control elements in a short time, said means operating said evolution strategy method using:
prior process knowledge in the form of a transfer function that reproduces a given dependency of output variables on the control variables, or
automatic adaptive process knowledge about the transfer function between local influence on thickness and actually measured values of the extrudate thickness distribution or both said prior process knowledge and said automatic adaptive process knowledge.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 08/081,279Filed 25 Jun 1993
Priority: DE 40 33 974.225 Oct 1990
Granted: 14 Mar 1995
Term ends: Not estimatedThe source records don’t support an estimate.

Classification19 codes

B29C 48/313
Being adjustable , i.e. having adjustable exit sections: by positioning the die lips
B29C 48/08
Flat, e.g. panels: flexible, e.g. films
B29C 48/10
Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels: flexible, e.g. blown foils
B29C 48/269
Component parts, details or accessories; Auxiliary operations: extrusion in non-steady condition, e.g. start-up or shut-down