WO2019198039A2

WO2019198039A2 - An integrated intelligent system and a method for estimating actual thickness of extruded films

Info

Publication number: WO2019198039A2
Application number: PCT/IB2019/053016
Authority: WO
Inventors: Siddharth LOHIA
Original assignee: Lohia Corp Limited
Priority date: 2018-04-14
Filing date: 2019-04-12
Publication date: 2019-10-17
Also published as: TWI707762B; TW202003201A; WO2019198039A3

Abstract

The present invention relates to a system and a method for accurately estimating the thickness of extruded plastic films. In particular, the invention relates to automatic allocation of a recipe-dependent calibration factor and a scanning system dependent calibration factor to the measured thickness to arrive at an accurate estimate. It also discloses making changes to the settings of the film forming die to reduce deviation of the actual thickness from the required thickness of the film. It addresses the problem faced by the conventional extrusion systems where the films are often of unacceptably non-uniform thickness. The invention comprises a PLC Controller unit (5) that is capable of receiving data from and sending it, in the form of electric signals, to other components of the system. PLC controller (5) makes computations of estimated actual thickness computation and computation of deviation of it from the required thickness. The PLC controller is also optionally capable of receiving instructions/data from and sending it to film forming die (6) to adjust the die-lip bolt settings.

Description

An Integrated Intelligent System And A Method For Estimating Actual Thickness Of Extruded Films

Field Of Invention:

The present invention relates to a method and an apparatus or a system (thickness measurement system or apparatus) for accurately measuring thickness of extruded plastic films. In particular, the invention relates to automatic allocation of a recipe- dependent calibration factor to the measured thickness and applying changes to the thickness measurement system settings to minimize deviation of actual thickness from the measured thickness. Further in particular, a gauging-system-dependent calibration factor may be applied.

Background Of Invention

A plastic extrusion machine is designed to produce endless flat plastic film/sheet or blown film of PP, HOPE, LLDPE or other blends of polyolefin. Due to the limitations of existing technology, the thickness of these continuous plastic films/sheets produced through extrusion machines has different thickness at different position and differs with time interval which may have caused due to the non-uniform melt flow across the die and which leads to non-uniform product. Ensuring that the variation between the actual and specified values of the thickness of a film/sheet manufactured on a high-speed extrusion process line is necessary to maximize uniform production. Moreover, changes to recipe compositions are also an essential part of the woven sack industry in order to increase profitability.

Conventionally, thickness of plastic film/sheet produced from extrusion machines is measured with various kind of scanning systems or other thickness measurement system available for dedicated purpose of measuring thickness of a film/sheet or blown film. These systems use online contactless measurement methods which use a source (emitter of some signal) and a detector (receiver of the signal) and where the source and detector are kept at either side of the fed film/sheet. The measurement through these scanning systems may not be the function of polymer, additive master batch or any other filler contents. Further, accuracy of such systems depend upon how much actual thickness varies from the measured thickness.

As per the conventional methods, thickness of the fed film/sheet depends on the filler material used in recipe of the composition. The thickness measurement systems are typically calibrated using one recipe. The actual recipes depend on the requirements of the individual sheet manufacturer and could be different from the one used to calibrate a system. In these circumstances, the settings of the thickness measurement devices should be changed using a calibration factor to match the actual recipes. If the actual recipe matches the one used for initial calibration of a thickness measurement system, no resetting is necessary. However, whenever changes are made to the recipe composition of the fed film/sheet, the thickness measured with a single calibration factor, would not be the actual thickness.

Technologies are available which address the problem of the variation between the measured and the actual film thickness up to certain extent. These use Beta gauge, X- ray gauge (diffraction or fluorescence), infrared gauge, capacitive measurement method etc. Technologies using Beta gauge is one of the most popular, however, as it involves a radioactive substances like Beta isotope there are drawbacks associated with it related to regulatory approvals, radiation-related health and safety matters, and half-life considerations. Alternatively, there are technologies that employ X-ray gauges, capacitive gauges, gamma back scatter gauge, or infrared gauges. The conventional systems are not capable of sensing the change in recipe composition. Further, to measure the actual thickness, one needs to enter a recipe- dependent the calibration factor manually on the Man Machine Interface (MMI) that typically control such systems to correctly measure the actual thickness. Moreover, the failure to change the calibration factor to reflect the actual recipe composition will lead result in a false measurement of the thickness, which will subsequently lead the operator (in the case of manual gauging systems) to adjust the film forming die settings to achieve the required thickness further changing the thickness of the produced film from the required specification. This leads to waste of human and material resources. Film forming die settings/adjustments are done through the manual adjustment of die- lip bolt; or in auto-guaging film forming die, through electric signal like voltage or pressure settings given to die-lip bolt of the film forming die. In auto-gauging systems, die-lip bolt settings are adjusted automatically on the basis of the signals sent by Programmable Logic Computing (PLC) Controller units that such systems deploy. In manual gauging systems, die-lip bolt settings are adjusted manually by human operators.

Some of the existing (prior art) systems are now examined. The patent US5418830A disclosed that measurement signal seems to be sensitive to the variation in density of air present in the gap between source and detector as well as beta and x-rays are very sensitive to material composition of the film/sheet which cannot be neglected. The patent US 4088886 discloses a method to find the calibration factor for running sheet material film by using X-ray florescence analyzer which provides measure of each quantity of metal alloy. However, its drawbacks are that the layout of this system is complicated and it only detects metal alloys in a composition. Therefore, this system is not suitable for measuring composition of plastic film materials. The analyzer is not suitable for tubular film like blown film where there is no place to measure the composition before the extrusion die.

The patent US 3988582 described the method of measuring the thickness using back scatter principle of a blown film where source and detectors are at outside of the blown film. This method, in which air under pressure is supplied to the interior of an elongate plastic bubble, is not accurate as air gap between source/detector head and the bubble changes because of varying air pressure inside the bubble. This variation in distance between sensor head and bubble causes an erroneous measurement of the film thickness. It is therefore evident that there is currently no technical solution on the market satisfactory for measuring the thickness of a relatively varying density of the plastic sheet without changing the calibration factor.

There is therefore a need to provide an in-production/online thickness measurement system for endless flat plastic film/sheet or blown film of PP, HOPE, LLDPE or other blends of polyolefin that will accurately measure the actual thickness of the produced film regardless of the recipe composition.

There is also a need to provide such systems that can be easily integrated with existing extrusion machines, dosing and mixing units, and can work with any of the thickness gauging system such as those use x-ray, beta, gamma, capacitive or infrared type or any other contactless method of measurement.

Further, there is a need for a system that will monitor the recipe composition of the film/sheet, and provide feedback to the detectors deployed by the thickness measurement systems in case of change in recipe composition in order to change the calibration factor automatically. This will eliminate the need manually to monitor the recipe changes and change the system settings accordingly. The measured thickness will thus reflect the actual recipe composition and will be closer to the actual thickness of the produced film as compared with the conventional systems.

Summary Of Invention:

The present invention discloses a method and an apparatus or a system (thickness measurement system or apparatus) for accurately estimating thickness of extruded plastic films. In particular, the invention discloses how to automatically allocate a recipe-dependent calibration factor to the measured thickness in order to arrive at an estimate of the film thickness. It also discloses how to apply a calibration factor based on the guaging (or scanning) technology to the measured thickness to further improve the accuracy of estimation. It further discloses how to adjust the settings of the film forming die, on the basis of the estimated thickness, so that the actual thickness of the extruded film is within the acceptable range of deviation from the required thickness. Further in particular, a gauging-system-dependent calibration factor may be applied. In order to do so, depending on the electric signals issued by the PLC Controller unit to the film forming die unit for settings of the die-lip bolt at required location may be adjusted depending on whether the estimated actual thickness is within the acceptable limits of deviation from the required thickness.

Brief Description Of Figures:

Figures 1 shows schematic of the intelligent integrated system of invention

Figure 1 A shows the block diagram of signal transfer used in the invention

Figure 2 shows the correlation between the measured thickness and actual thickness Figure 2A shows the discrete points used for measurement of thickness

Figure 3 shows the typical curve from which calibration factor is determined

List Of Parts:

1 - Dosing and mixing unit 2A - Cooling system

2 - Extruder 2B - Plastic film 3 - Guaging/scanning system 5 - PLC controller 3A - Discrete point 6 - Film forming Die

4 - First database of recipes and 10 S - integrated intelligent film corresponding calibration factors thickness measurement system 4A - Second database of gauging

systems and corresponding calibration

factors

Detailed Description Of The Invention

The present invention provides a method for continuously reducing measurement deviations in film thickness measurement for flat/circular/blown film/sheet and point- to-point annular deviations in film thickness measurement for tubular film. The method detects change in the proportion of the filler or other essential components of the said film/sheet and uses a varying recipe calibration factor as per the changed recipe of the composition. The invention discloses an integrated intelligent film thickness system and a method for continuous change in recipe calibration factor.

For the purpose of this invention, the recipe calibration factor is defined as the ratio of measured thickness (measured using the measuring system/technology and the associated software) to actual thickness of the extruded film (2B). Alternatively, the terms recipe gauge factor, recipe correction factor, or recipe proportionality factor are used to describe it.

For the purpose of this invention, the recipe has been defined in terms of the essential or key ingredients of a composition. For example, a recipe may be defined simply in terms of the inorganic content and polymer content. In some other case, the recipe may be defined in terms of the polymers, additives, etc. Depending on the application of the film, the essential ingredients of a recipe may be determined. As a part of the invention, a comprehensive first database (4) of recipes and corresponding recipe calibration factors is created using any system of measuring the actual film thickness. The first database (4) is created on the basis of measurement of the film thickness for films of a number of recipes in controlled environment. The recipe calibration factors for a large number of recipes are already saved in a database (4). The first database (4) is created after performing number of experiments and resulting data saved in the first database (4) for most of the recipe used in the industry. The greater the number of recipes tested for creation of the first database (4), the better the accuracy of the recipe calibration factor. In the case, there’s a new recipe available, which is already not a part of the first database (4), the first database (4) is capable of being updated to store the new recipe and the corresponding recipe calibration factor. It should also be noted that the accuracy of the thickness measurement is dependent on the different technologies deployed by the gauging systems - e.g. beta rays, x-ray, gamma rays, capacitive or infrared rays. This is because of the technological limitations of specific systems and the specific algorithms deployed by them. This means that the measurements carried out by different gauging techniques may be different.

The present invention also accounts for these dependencies by applying a further factor, termed as a‘gauging system calibration factor’ to the recipe calibration factor to arrive at the‘final calibration factor’. The gauging system calibration factor is determined by measuring the same fdm using different technologies and arriving at the ratio of the measured thickness with the actual thickness. The gauging system calibration factor may be determined for sheet produced using any one recipe and holds true for sheets produced using any other recipe. In order to measure thickness of a film of a recipe of any given specification, a closest match is found in the first database (4) for the components of the specified recipe. The match may be exact or it may be extrapolation between any two or more points of the first database (4). A corresponding recipe calibration factor is then computed by extrapolating between corresponding recipe calibration factors in the first database

(4).

Practically, it is observed that the film thickness measurement system generates calculation error while showing the thickness on the display screen like an MMI (Man Machine Interface - not shown) when the recipe (the percentage of polymer material or any other filler component) changes. Conventionally, as a corrective action the machine operator needs to input new calibration value or recipe values on MMI of the thickness measurement/scanning system to change its computing algorithm, every time recipe composition is changed in the dosing and mixing unit. In the present invention, the first database (4) stored in the PLC (Programmable Logic Computing/Controller) controller controls the selection of recipe calibration factor corresponding to different recipe.

Figure 1 shows the block diagram of the intelligent integrated film thickness measurement system of invention to measure the thickness of a film. It shows a dosing and mixing unit (1) which supplies raw material to the extruded film manufacturing unit or extrusion unit or simply the extruder (2). The extruder (2) is capable of producing a flat or circular or blown type film through the film forming die (6). The film (2B) that is formed by the film forming die (6) proceeds to a gauging system (3) (alternatively a gauging unit or a gauging device) that scans the film (2B) and collects data regarding the film’s thickness at discrete points (3 A) across the width of the film (2B). The gauging system (3) is capable of using any conventional technologies of thickness measurement such as beta rays, x-ray, gamma rays, capacitive or infrared rays.

The film forming die may be linear type (which produces a flat sheet with edges) or annular type (which produces a tubular film). The discrete points (3 A) may be spread across the entire width of the flat film or throughout the perimeter of the tubular film. The film forming die has die bolts; each die bolt corresponding to at least one discrete point (3A). The scanning system (3) measures thickness at least at discrete points (3 A). It may collect data at other points on the film (2B). The first database (4) itself is stored within a PLC Controller unit (5). The recipe composition of the film that is being scanned is compared with the recipes inside the first database and on the basis of which a calibration factor suitable for the current recipe is selected from the database by the PLC Controller unit (5). Using the selected recipe calibration factor, a correction is applied by the PLC Controller Unit (5) to the measured thickness at discrete points (3 A) to arrive at the best estimate of the actual thickness at discrete points (3 A) of the film. In other words the measured thickness is multiplied by the recipe calibration factor to arrive at the estimated actual thickness at the discrete points (3 A) of the extruded film (2B).

The thickness data is collected by the scanning unit (3) at discrete points (3 A) across the width of the fdm (2B). The fdm forming die has a number of die-bolts spread across the width of the film. Depending on the deviation of the estimated actual thickness from the required or specified thickness at discrete points (3A) across the width of the film (2B), a signal is sent by the PLC Controller unit (5) to the film forming die (6) so as to adjust the settings of die-lip-bolt unit (not shown) to minimize the deviation at a location corresponding to a particular one or more discrete point (3 A) along the width of the film (2B). This process of adjustment of the die-lip bolts is automated in the case of automated gauging film forming die systems and manual in the case of manual automated gauging film forming die systems. The adjustment process is also iterative and carried out until the deviation at all discrete points (3 A) is within the acceptable limit. At this stage, the estimated overall thickness of the film (2B) itself is determined by averaging the estimated thickness measured at discrete points (3A). Any averaging technique such as statistical method/technique of averaging, including computing simple arithmetic average, may be used. It is important to note that there’s a time lag between the time when the raw material is fed to the mixing and dosing unit and when the film comes to the scanning unit of the gauging system. As an optional feature, a second database (4A) of gauging systems and corresponding gauging system calibration factors is also maintained within the PLC Controller Unit (5). The gauging system calibration factor corresponding to the actual system of thickness measurement used is applied to the recipe calibration factor to arrive at the final calibration factor which is applied to the measured thickness to arrive at the estimated actual thickness. In other words, the recipe calibration factor is multiplied by the gauging system calibration factor to arrive at the final calibration factor.

In the systems that do not have the optional feature of the second database (4A), the final calibration factor is the same as the recipe calibration factor.

If anytime during the process of manufacturing the recipe is changed, the PLC Controller (5) is notified by the mixing and dosing unit (1) of the time of feeding of new recipe to the dosing and mixing and unit (1) and the details of the recipe composition itself. Time of arrival of the film manufactured according to the new recipe is calculated on the basis of the production speed of the extruder. The PLC Controller (5) resets the recipe calibration factor at a time to coincide with the arrival of the film (2B) of the new recipe at the gauging unit and uses it to calculate estimated actual film thickness. Thus once the recipe of the composition has been fed to the system at the dosing and mixing unit, no further input is required with regards the recipe at any other point in the fdm production process.

The detail of recipe from dosing and mixing unit (1) is communicated to PLC controller (5) and compared with the first database (4) which is stored in PLC controller (5) itself. The PLC controller (5) provides a representation of an integrated intelligent film thickness measurement system (S) which is a control system which links dosing and mixing unit (1) and gauging system (3) with the first database (4). The integrated intelligent film thickness measurement system (S) automatically updates the changes in dosing unit (1) in suitable time interval to the film thickness scanning system. The PLC controller (5) is a main controller of the complete extrusion machine and responsible for many functions apart from the ones such as running the extruder, reading the temperature and pressure of different components of an extrusion machine. It is a master controller responsible for any logic control in the complete system.

The details of measuring thickness by scanning systems using various technologies such as beta rays, x-ray, gamma rays, capacitive or infrared rays are already known and therefore not explained in detail here. It has been found that any of the existing contact type or contactless online thickness gauges may be used for the thickness measurement purpose in the system of the invention.

The second database (4A) is capable of accepting data for new thickness measuring technologies as and when they are available.

A person skilled in the art is aware that the recipes change a number of times during the manufacture of a film depending on the customer requirement or specific purpose for which the film is manufactured. Let us assume that a film requires A, B, and C as raw materials supplied to the dosing and mixing unit in proportions x%, y%, and z % respectively. At the start of the manufacturing process, this information is fed to the system. The PLC Controller (5), with the help of the databases (4, 4A), calculates/allocates a calibration factor and corrected the measured thickness value to actual thickness of film. As stated earlier, the invention provides the capability of adjusting required location die-lip bolt settings depending on the changes to recipe and the resultant deviation of the estimated actual thickness from the required or specified thickness.

This leads to a significant improvement in the consistency and uniformity and compliance of the actual thickness of the manufactured film with the required thickness expected from a given recipe. More importantly, and unlike the conventional systems, the risk of the operator failing to notice the recipe change and changing the extruder and gauging system settings - which will adversely affect the uniformity and consistency of the film and lead to wastage - is completely avoided in the system of invention.

The method of invention uses an integrated intelligent thickness measurement system (S) incorporating an extrusion machine and controls the filler composition detail from the separate/common man-machine interface (MMI) of dosing and mixing unit (1). Further the method takes cognizance of the change in recipe material, determine the need to recalculate and reset the calibration factor at the time when the film manufactured arrives at the gauging system. The method also takes cognizance of the technology deployed at the gauging unit and further modifies the calibration factor to arrive at a final calibration factor. This integration brings the complete system on a common controlling platform to reduce the manual errors in compensating for recipe (through the use of the recipe calibration factor) and measurement technology changes (through the use of the gauging calibration factor).

Figure 2 shows a block diagram that represents that measured thickness from gauge may not be the actual thickness of the manufactured film (2B). The method of invention allows making an estimate of the actual thickness on the basis of the measured thickness by applying a calibration factor or a final calibration factor. The estimated actual thickness of a manufactured film as calculated using the method of invention is far superior than the thickness estimated using conventional methods.

Figure 3 represents the behavior of calibration factor with respect to different recipe contents. The amount of change in calibration factor depends upon filler/ content material of the extruded film and type of thickness gauge used in the system.

To accomplish the specific task of updating film thickness measurement system automatically upon change in recipe, an integrated intelligent film thickness measurement system and a method for continuous change in calibration factor is developed. This integrated intelligent system is a combination of dosing and mixing unit, online thickness measurement system and database. Thickness measurement system can be linked with dosing and mixing unit and complete extrusion machine through any conventional methods of communication.

To have seamless change in process control, the integrated intelligent film thickness measurement system ensures real time updating to the scanning system (3) considering the delay of material movement from the dosing and mixing unit to the scanning system. This minimizes any kind of computational error in the scanning system (3) due to the material flow delay. Material flow delay can vary with the line speed of the machine. The system will calculate delay of material flow and then intelligently assign the recipe calibration factor to the gauging system (3).

The dosing and mixing unit (1) is designed such that it keeps record of each component of material which is selected through its MMI and transfers new recipe parameters to the scanning system on detection of every change. The dosing and mixing unit can communicate updated parameters to film thickness measurement system on redundant digital or analog bus in case of integrated and distributed systems, which ensures delivery of relevant parameters between units.

According to the invention a method for online thickness measurement of extruded films is disclosed. The method comprises the following steps:

a. Providing an intelligent integrated film thickness measurement system (S) comprising a dosing and mixing unit (1), an extruder unit (2), a scanning system (3), a film forming die unit (6), a first database (4) of recipe calibration factors, an optional second database (4A) of gauging system calibration factors, a PLC Controller unit (5), wherein said PLC Controller unit is capable of controlling operations of other units of the system (S);

b. Feeding raw material to a dosing and mixing unit (1) and subsequently making and extruded film (2B) from an extruder unit (2) through film forming die (6) ; c. Feeding/Notification from said dosing and mixing unit (1) to a PLC controller (5) information about the composition of the raw material;

d. Selecting a recipe calibration factor on the basis of the recipe composition of the raw material;

e. Measuring the thickness of the extruded continuous film (2B) using a gauging unit (3) at at least one discrete point - preferably at all discrete points (3 A); f. Selecting/Allocation of a gauging calibration factor on the basis of the technology deployed by the gauging unit (3);

g. Applying the calibration factor and the gauging calibration factor to the measured thickness to compute the estimated actual thickness at discrete points (3 A);

h. The PLC controller (5) computing the deviation between the required film thickness and the estimated actual thickness and checking whether the deviation is greater than a predetermined acceptable limit, and making a record of the corresponding discrete points (3 A);

i. As an optional step, if the deviation is greater than the predetermined acceptable limit, the PLC controller (5) computing and sending electric signals to film forming die (6) so that adjustment may be made to the setting of the die-lip bolt corresponding to the recorded discrete points (3 A) to bring said deviation within said predetermined acceptable limit; j. Repeating steps f and h until the deviation is greater than or equal to the predetermined acceptable limit.

According to another aspect of the invention an intelligent integrated film thickness measurement system (S) or an apparatus is disclosed to carry out the method disclosed herein. The system or the apparatus comprises:

A dosing and mixing unit (1) capable of receiving raw material and mixing it and sending it down to an extruder unit (2). The dosing and mixing unit is also connected to a PLC controller (5) to which data regarding the composition of ingredients of the film to be produced are fed.

The extruder unit (2) being capable of receiving the raw material from the dosing and mixing unit (1) and manufacturing a film (2B) through a film forming die (6).

The gauging unit (3) for scanning the film (2B) for measurement of its thickness.

The PLC controller (5) controls the manufacturing process and also houses a first database (4) of recipes and corresponding calibration factors. It also optionally contains a second database (4A) of gauging technologies and corresponding gauging calibration factors. The PLC controller (5) is capable of receiving data from and sending it, in the form of electric signals, to other components of the apparatus such as the mixing and dosing unit (1), and the gauging unit (3). PLC controller (5) makes the necessary computations such as estimated actual thickness computation and computation of deviation of the estimated actual thickness from the required thickness of the film (2B). The PLC controller is also optionally capable of receiving instructions/data from and sending it to film forming die (6) to adjust the die-lip bolt settings.

The gauging unit (3) scans the film (2B) and obtains thickness measurements at discrete points (3A) and sends it back to the PLC controller (5) for estimated actual thickness computation at discrete points (3 A). The main advantage of the inventive system is to have real time seamless updating of changes in process/receipe to the thickness measurement and control system without any human interference, ensuring uniform desired film product.

Example:

An extruded film of actual thickness of 80 microns, and whose inorganic content was around 40% and polymer content around 60% was measured using conventional method and conventional thickness measuring system. The measuring system had a fixed single gauging factor of 1.5. The measured thickness was therefore 115 microns and the resultant difference/error between actual film thickness and measured film thickness was around 44%. The thickness of the same film was assessed using the system of invention operating using an X-ray gauging method. On the basis of the inorganic content and the rest of the recipe of the raw material, a recipe gauge factor of 0.8 was assigned. The estimated actual thickness calculated according to the method of invention was therefore 78 micron. This is around 2.5% deviation from the actual thickness.

It is evident from the foregoing description that the invention has the following embodiments:

1. An integrated intelligent system (S) for estimating actual thickness of extruded films, characterized in that said system is capable of measuring thickness of said extruded film (2B) and modifying it by a final calibration factor to compute estimated actual thickness at discrete points (3A) of said film.

2. The system (S) as disclosed in embodiment 1, wherein said system comprises: a dosing and mixing unit (1) capable of receiving raw material and mixing it wherein said dosing and mixing unit (1) is also connected to a PLC controller (5) to which data regarding the composition of ingredients of the film to be produced are fed;

an extruder unit (2) which receives the raw material from said dosing and mixing unit (1) and manufactures an extruded fdm (2B) through a film forming die (6); a gauging unit (3) for scanning said extruded film (2B) for thickness measurement, wherein said gauging unit scans the film (2B) and obtains measurement of actual thickness at predetermined discrete points (3 A) across the width of said film (2B) and sends said obtained measurements back to said PLC controller (5) for estimated actual thickness computation; wherein said PLC controller (5) controls manufacturing process of said extruded film (2B) and also houses a first database (4) of raw material recipes and corresponding recipe calibration factors, and wherein said PLC controller (5) is capable of receiving data from and sending data to other components of the system such as said dosing and mixing unit (1), said extruder unit (2), and said gauging unit (3); further wherein said PLC controller (5) being capable of determining a recipe calibration factor and making the necessary computations such as estimated actual thickness computation and computation of deviation of the estimated actual thickness from the required thickness of the film at said discrete points (3A), and, optionally, on the basis of said computations, sending electric signal to the film forming die (6) to adjust the die bolt settings.

The system as disclosed in embodiment 2, wherein said PLC controller (5) optionally stores a second database (4A) of gauging calibration factors corresponding to available gauging technologies. The system as disclosed in embodiment 2, wherein said estimated actual thickness computation consists of multiplying the actual measured thickness of said film (2B) by said recipe calibration factor, said estimated actual thickness computation being carried out at discrete points (3A) where estimated actual film thickness has been measured.

The system as disclosed in embodiment 3, wherein said estimated actual thickness computation consists of multiplying the actual measured thickness of said film (2B) by said recipe calibration factor and by said gauging calibration factor, said estimated actual thickness computation being carried out at discrete points (3 A) where estimated actual film thickness has been measured.

The system as disclosed in embodiments 1 to 5, wherein said PLC controller (5), on the basis of said computations, is capable of sending electric signal to the film forming die (6) to adjust the settings of individual die-lip bolts of said die (6).

The system as disclosed in embodiments 1 to 6, wherein the overall estimated actual thickness of the film is computed by averaging estimated actual thickness at discrete points (3 A) using an averaging technique.

The system as disclosed in embodiments 1 to 7, wherein the averaging technique is simple arithmetic averaging. 9. The system as disclosed in embodiments 1 to 8, wherein corresponding to every die-lip bolt, there is at least one discrete point (3 A).

10. The system as disclosed in embodiments 1 to 9, wherein said first database (4) is capable of accepting data for new recipes as and when they are available. 11. The system as disclosed in embodiments 1 to 10, wherein said second database (4A) is capable of accepting data for new thickness measuring technologies as and when they are available.

12. A method for estimating online actual thickness of extruded films using the intelligent integrated system (S) of claims 1 to 11, characterized in that said method of estimating comprises measuring thickness of said extruded film

(2B) and modifying it by a final calibration factor to compute estimated actual thickness at discrete points (3 A) of said film (2B).

13. The method as disclosed in embodiment 12, wherein said method of estimating comprises the sequential steps of:

a. providing an integrated intelligent system (S) as claimed in any of claims

1 to 11 ;

b. feeding raw material to said dosing and mixing unit (1) required for extruding a film (2B);

c. feeding or sending a notification to said PLC controller (5) information about the composition of the raw material; d. selecting a recipe calibration factor from said first database (4) on the basis of the recipe composition of said raw material;

e. measuring the thickness at discrete points (3 A) of the extruded continuous film (2B) using said gauging unit (3);

f. applying said recipe calibration factor to the measured thickness of said step e at discrete points (3A) to compute the measured estimated actual thickness at discrete points (3 A);

g. computing deviation of said measured estimated actual thickness at discrete points (3 A) from required thickness of film, and said PLC controller (5) sending electric signals to said film forming die and adjusting settings of individual die-lip bolts.

The method as disclosed in embodiment 13, wherein using said PLC controller (5) to compute the deviation between the required film thickness and the estimated actual thickness and checking whether the deviation is less than a predetermined acceptable limit, and repeating said step g until the deviation is less than or equal to the predetermined acceptable limit.

The method as disclosed in embodiments 13 and 14, wherein if said deviation is greater than a predetermined acceptable limit, the PLC controller (5) computing adjustments to be made to the die bolts and applying the adjustments to the individual die-bolts. 16. The method as disclosed in embodiments 13 to 15, wherein said PLC controller (5) optionally storing a second database (4A) of gauging calibration factors corresponding to available gauging technologies, and applying said gauging calibration factor to said estimated actual thickness of said step e, to amend the said estimated actual thickness.

17. The method as disclosed in embodiment 15, wherein said estimated actual thickness computation is carried out at all discrete points (3A) where actual film thickness has been measured.

18. The method as disclosed in embodiment 16, wherein on the basis of said computations, said PLC Controller (5) sending electric signals to the extruder unit (2) to adjust the die bolt settings.

19. The method as disclosed in embodiments 12 to 18, wherein amending said first database (4) to incorporate data for new recipes as and when they are available.

20. The method as disclosed in embodiments 16 to 18, wherein amending said second database (4A) by incorporating data for new thickness measuring technologies as and when they are available.

While the above description contains much specificity, these should not be construed as limitation in the scope of the invention, but rather as an exemplification of the preferred embodiments thereof. It must be realized that modifications and variations are possible based on the disclosure given above without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.

Claims

Claims:

1. An integrated intelligent system (S) for estimating actual thickness of extruded films, characterized in that said system is capable of measuring thickness of said extruded film (2B) and modifying it by a final calibration factor to compute estimated actual thickness at discrete points (3 A) of said film.

2. The system (S) as claimed in claim 1, wherein said system comprises:

a dosing and mixing unit (1) capable of receiving raw material and mixing it wherein said dosing and mixing unit (1) is also connected to a PLC controller (5) to which data regarding the composition of ingredients of the film to be produced are fed;

an extruder unit (2) which receives the raw material from said dosing and mixing unit (1) and manufactures an extruded film (2B) through a film forming die (6);

a gauging unit (3) for scanning said extruded film (2B) for thickness measurement, wherein said gauging unit scans the film (2B) and obtains measurement of actual thickness at predetermined discrete points (3 A) across the width of said film (2B) and sends said obtained measurements back to said PLC controller (5) for estimated actual thickness computation; wherein said PLC controller (5) controls manufacturing process of said extruded film (2B) and also houses a first database (4) of raw material recipes and corresponding recipe calibration factors, and wherein said PLC controller (5) is capable of receiving data from and sending data to other components of the system such as said dosing and mixing unit (1), said extruder unit (2), and said gauging unit (3); further wherein said PLC controller (5) being capable of determining a recipe calibration factor and making the necessary computations such as estimated actual thickness computation and computation of deviation of the estimated actual thickness from the required thickness of the film at said discrete points (3A), and, optionally, on the basis of said computations, sending electric signal to the film forming die (6) to adjust the die bolt settings.

3. The system as claimed in claim 2, wherein said PLC controller (5) optionally stores a second database (4A) of gauging calibration factors corresponding to available gauging technologies.

4. The system as claimed in claim 2, wherein said estimated actual thickness computation consists of multiplying the actual measured thickness of said film (2B) by said recipe calibration factor, said estimated actual thickness computation being carried out at discrete points (3 A) where estimated actual film thickness has been measured.

5. The system as claimed in claim 3, wherein said estimated actual thickness computation consists of multiplying the actual measured thickness of said film

(2B) by said recipe calibration factor and by said gauging calibration factor, said estimated actual thickness computation being carried out at discrete points (3 A) where estimated actual film thickness has been measured.

6. The system as claimed in claims 1 to 5, wherein said PLC controller (5), on the basis of said computations, is capable of sending electric signal to the film forming die (6) to adjust the settings of individual die-lip bolts of said die (6).

7. The system as claimed in claims 1 to 6, wherein the overall estimated actual thickness of the film is computed by averaging estimated actual thickness at discrete points (3 A) using an averaging technique.

8. The system as claimed in claims 1 to 7, wherein the averaging technique is simple arithmetic averaging.

9. The system as claimed in claims 1 to 8, wherein corresponding to every die-lip bolt, there is at least one discrete point (3 A).

10. The system as claimed in claims 1 to 9, wherein said first database (4) is capable of accepting data for new recipes as and when they are available.

11. The system as claimed in claims 1 to 10, wherein said second database (4A) is capable of accepting data for new thickness measuring technologies as and when they are available.

12. A method for estimating online actual thickness of extruded films using the intelligent integrated system (S) of claims 1 to 11, characterized in that said method of estimating comprises measuring thickness of said extruded fdm (2B) and modifying it by a final calibration factor to compute estimated actual thickness at discrete points (3 A) of said film (2B).

13. The method as claimed in claim 12, wherein said method of estimating comprises the sequential steps of:

a. providing an integrated intelligent system (S) as claimed in any of claims 1 to 11 ;

c. feeding or sending a notification to said PLC controller (5) information about the composition of the raw material;

d. selecting a recipe calibration factor from said first database (4) on the basis of the recipe composition of said raw material;

f. applying said recipe calibration factor to the measured thickness of said step e at discrete points (3 A) to compute the measured estimated actual thickness at discrete points (3 A);

g. computing deviation of said measured estimated actual thickness at discrete points (3A) from required thickness of film, and said PLC controller (5) sending electric signals to said film forming die (6) and adjusting settings of individual die-lip bolts.

14. The method as claimed in claim 13, wherein using said PLC controller (5) to compute the deviation between the required film thickness and the estimated actual thickness and checking whether the deviation is less than a predetermined acceptable limit, and repeating said step g until the deviation is less than or equal to the predetermined acceptable limit.

15. The method as claimed in claims 13 and 14, wherein if said deviation is greater than a predetermined acceptable limit, the PLC controller (5) computing adjustments to be made to the die bolts and applying the adjustments to the individual die-bolts.

16. The method as claimed in claims 13 to 15, wherein said PLC controller (5) optionally storing a second database (4A) of gauging calibration factors corresponding to available gauging technologies, and applying said gauging calibration factor to said estimated actual thickness of said step e, to amend the said estimated actual thickness.

17. The method as claimed in claim 15, wherein said estimated actual thickness computation is carried out at all discrete points (3 A) where actual film thickness has been measured.

18. The method as claimed in claim 16, wherein on the basis of said computations, said PLC Controller (5) sending electric signals to the extruder unit (2) to adjust the die bolt settings.

19. The method as claimed in claims 12 to 18, wherein amending said first database (4) to incorporate data for new recipes as and when they are available.

20. The method as claimed in claims 16 to 18, wherein amending said second database (4A) by incorporating data for new thickness measuring technologies as and when they are available.