EP-4737096-A1 - METHOD FOR OPTIMIZING A WORKING PROCESS

EP4737096A1EP 4737096 A1EP4737096 A1EP 4737096A1EP-4737096-A1

Abstract

A method for optimizing a working process implemented by a computer, the process comprising at least: a heating step of a semi-finished product; a forming step, wherein the semi-finished product is transformed into an intermediate product; a cooling step, wherein the intermediate product is transformed into a manufactured article, the method comprising an algorithm operating according to the following steps: a definition step, wherein process parameters are defined; process variables having values that vary with the variation of at least one of the process parameters; a constraint interval comprising an interval of selected values of the variables; a first selection step, wherein one of the process parameters is chosen as a selected parameter; a simulation step, subsequent to the selection step, wherein the value of the selected parameter is progressively varied within a selected interval of values of the selected parameter, and for each value of the selected parameter, the corresponding values of the variables are calculated; an acquisition step, wherein for each value of the selected parameter within the selected interval, the corresponding values of the variables are recorded, each value of the selected parameter and the corresponding values defining a set of values; the sequence of the first selection step, the simulation step, and the acquisition step being repeated for each selected parameter chosen from the process parameters; a second selection step wherein each set is selected for each selected parameter wherein the corresponding values of the variables are included within a respective constraint interval.

Inventors

ALDINIO-COLBACHINI, Daciano
SCHIAVO, Fabio

Assignees

Solera-Thermoform Group SpA

Dates

Publication Date: 20260506
Application Date: 20241030

Claims (15)

A method for optimizing a working process implemented by a computer, said process comprising at least: - a heating step of a semi-finished product; - a forming step, wherein said semi-finished product is transformed into an intermediate product; - a cooling step, wherein said intermediate product is transformed into a manufactured article, and characterized in that said method comprises an algorithm operating according to the following steps: - a definition step, wherein the following are defined: - process parameters associated with said process; - process variables having values that vary with the variation of at least one of said process parameters; - a constraint interval comprising an interval of selected values of said variables; - a first selection step, wherein one of said process parameters is chosen as a selected parameter; - a simulation step, subsequent to said selection step, wherein the value of said selected parameter progressively changes within a selected interval of values of said selected parameter, and for each of said values of said selected parameter, the corresponding values of said variables are calculated; - an acquisition step, wherein for each value of said selected parameter within said selected interval, the corresponding values of said variables are recorded, each said value of said selected parameter and said corresponding values defining a set of values; - the sequence of said first selection step, said simulation step, and said acquisition step being repeated for each selected parameter chosen from said process parameters; - a second selection step wherein each said set is selected for each said selected parameter wherein the corresponding values of said variables are included within a respective said constraint interval.
The method according to claim 1, wherein the following are defined: - a first surface corresponding to the free surface of said semi-finished product as it is not in contact with the wall of a mold, wherein said forming step and said cooling step take place; - a second surface corresponding to the surface of said semi-finished product in contact with said wall during said forming and cooling steps; - a core corresponding to the internal portion of said semi-finished product positioned at the greatest distance from said first surface and said second surface, said process parameters comprising: - material parameters corresponding to the parameters of said semi-finished product associated with the properties of the material of said semi-finished product; - method parameters associated with the implementation of said working process; - instrumental parameters associated with the instrumentation used to implement said working process.
The method according to the preceding claim, wherein said material parameters comprise the type of material and at least one selected from: - material density; - specific heat; - thermal conductivity; - glass transition temperature.
The method according to at least claim 2, wherein said method parameters comprise at least one selected from: - size of said semi-finished product; - shape factor; - mold temperature; - delivered power; - transition temperature, wherein during said heating step, the average value of said delivered power is varied; - mold temperature - temperature at the end of said heating step corresponding to the temperature at which said heating step ends; - duration of said heating step; - duration of said forming step; - duration of said cooling step.
The method according to claim 2, wherein said instrumental parameters comprise at least one selected from: - the geometry of the mold; - the size of the mold; - the maximum deliverable power; - environmental temperature.
The method according to any of the preceding claims, wherein said variables comprise at least one selected from: - temperature of said first surface; - temperature of said second surface; - temperature of said core; - difference in temperature between said first surface and said core; - difference in temperature between said second surface and said core; - duration of said heating step; - duration of said forming step; - duration of said cooling step; - total duration of said process; - number of sub-steps into which said heating step can be divided; - delivered power of each of said sub-steps; - transition temperatures from one of said sub-steps to the next corresponding to temperatures of said semi-finished product at which, during said heating step, the transition from one of said sub-steps to the next occurs; - thermal flux of said semi-finished product during said heating step; - total delivered energy corresponding to the energy delivered during the entire working process.
The method according to at least the preceding claim, wherein said variables comprise at least one selected from: - initial temperature of said semi-finished product corresponding to the temperature of said semi-finished product at the beginning of said process; - maximum temperature of said first surface at the end of said heating step; - maximum temperature of said second surface at the end of said heating step; - difference between the maximum temperature of said first surface and the temperature of said core; - difference between the maximum temperature of said second surface and the temperature of said core; - temperature of said first surface at the end of said heating step; - temperature of said second surface at the end of said heating step; - temperature of said core at the end of said heating step; - temperature of said first surface during said cooling step; - temperature of said second surface during said cooling step; - difference between said temperature of said first surface and said temperature of said second surface during said cooling step; - delivered power during said heating step; - difference between a first temperature of said mold and a second temperature of said mold, the latter corresponding to the temperature of said mold.
The method according to any of the preceding claims, wherein in said second selection step, each said set is selected for said selected parameter for which the corresponding values of said variables are all included within a respective said constraint interval.
The method according to any of the preceding claims, wherein in said definition step, the values of said constraint interval are provided as input by a user.
The method according to any of the preceding claims, comprising a database, said database comprising said material parameters, in said definition step said algorithm associating with each of said material parameters the corresponding values in response to the selection of the material class.
The method according to claim 6, wherein: - said constraint interval of said temperature of said first surface comprises a maximum value corresponding to the maximum temperature of said first surface; - said constraint interval of said temperature of said second surface comprises a maximum value corresponding to the maximum temperature of said second surface; - said constraint interval of said temperature of said core comprises a minimum value corresponding to the minimum temperature of said core; - said constraint interval of said temperature of said cooling step comprises a maximum value corresponding to the maximum temperature of said cooling step; - said constraint interval of said temperature of said cooling step comprises a minimum value corresponding to the minimum temperature of said cooling step.
The method according to any of the preceding claims, wherein parameters to be optimized are defined from among said variables, and for each of said parameters to be optimized, an optimization interval corresponding to an interval of selected values of the corresponding said parameters to be optimized is defined, and wherein said algorithm operates according to an optimization step, subsequent to said second selection step, wherein said sets, having the values of said parameters to be optimized simultaneously included within their respective said optimization interval, are selected.
The method according to the preceding claim, wherein said parameters to be optimized and each said optimization interval are selected in a step chosen between said definition step and said optimization step.
The method according to any of claims 6-7, wherein said algorithm operates according to a verification step, subsequent to said second selection step, wherein it acquires said sets associated with at least one selected from: - a temperature profile of said first surface as a function of time; - a temperature profile of said second surface as a function of time; - an energy delivery profile as a function of time.
The method according to any of the preceding claims, wherein said process is a vacuum thermoforming and said semi-finished product is a sheet.

Description

METHOD FOR OPTIMIZING A WORKING PROCESS The present invention relates to a method for optimizing a working process of the type specified in the preamble of the first claim. The object of the present invention is a method for optimizing a working process which finds application in the field of material processing and primarily, but not exclusively, in the field of polymeric material processing. Currently, processing techniques for semi-finished products that allow for the making of manufactured articles are known. In detail, these processing techniques may include molding methods. In these techniques, the material can be inserted into a mold and undergoes to a deformation process that allows the material to acquire the desired shape of the mold. These techniques can be hot or cold, depending on the values of the process temperatures. For example, a hot molding process is the injection molding, wherein the material, typically polymeric, is melted and injected into the mold until its internal cavity is filled, then cooled and extracted from the mold. Another molding technique is vacuum thermoforming, wherein a sheet of polymeric material is laid on the mold by means of a vacuum. The sheet is heated by heating elements (typically lamps) and rendered malleable so that it can be deformed. The vacuum created within the mold draws the sheet towards the mold and deforms it so that it adheres to the mold until it takes the shape thereof. At the end of the forming, the manufactured article thus obtained then undergoes a controlled cooling and is extracted from the mold. The known techniques described include some significant drawbacks. In particular, they require the control of a plurality of parameters that may conflict with each other. This aspect makes it more complex to find sets of parameter values that allow achieving the best performance of the process, for example, in terms of time, energy consumption, and quality of the manufactured article. In this situation, the technical task underlying the present invention is to devise a method for optimizing a working process capable of substantially overcoming at least part of the cited drawbacks. Within said technical task, an important purpose of the invention is to obtain a method for optimizing a working process capable of optimizing the parameters of a working process. Another important purpose of the invention is to create a method for optimizing a working process that allows reducing the duration of a working process. The technical task and the specified purposes are achieved by a method for optimizing a working process as claimed in the appended claim 1. Preferred technical solutions are highlighted in the dependent claims. In this document, measurements, values, shapes, and geometric references (such as perpendicularity and parallelism), when associated with words like "approximately" or other similar terms such as "about" or "substantially", are to be understood as subject to measurement errors or inaccuracies due to production and/or manufacturing errors and, above all, subject to a slight deviation from the value, measurement, shape, or geometric reference to which it is associated. For example, such terms, if associated with a value, preferably indicate a deviation not exceeding 10% of the value itself. Moreover, when used, terms like "first", "second", "upper", "lower", "main", and "secondary" do not necessarily identify an order, priority of relation, or relative position but may simply be used to more clearly distinguish between different components. Unless otherwise specified, as apparent from the following description, terms such as "processing", "computing", "determination", "computation", or similar refer to the action and/or processes of a computer or similar electronic computation device that manipulates and/or transforms data represented as physical quantities, such as electronic magnitudes of records of a computing system and/or memories into other data similarly represented as physical quantities within computer systems, records, or other storage, transmission, or information display devices. The measurements and data reported in this text are to be considered, unless otherwise indicated, as performed in International Standard Atmosphere ICAO (ISO 2533:1975). The invention comprises a method for optimizing a working process implemented by a computer. The working process may be a forming process that allows the production of a manufactured article. For example, the process may preferably be a vacuum thermoforming. Moreover, the semi-finished product may be a sheet. The process includes at least one heating step of a semi-finished product. In the heating step, the semi-finished product is heated in such a way as to reach a desired temperature. Furthermore, the heating step may allow achieving a desired thermal gradient between portions at different depths of the semi-finished product. The heating can be performed by the administration of heating