Method for controlling a facility for producing containers

Abstract

The present invention relates to a method for manufacturing containers (23) made of thermoplastic materials in a facility (1) comprising at least a first unit (2) for producing preforms (3) and a second unit (10) for producing containers by blow moulding or stretch-blow moulding the preforms (3) previously produced by the first unit (2); said method being noteworthy in that it comprises at least the following steps: measuring at least one physical quantity of at least one preform (3) or at least one container (23) and / or of at least one physical quantity of at least one of the steps of the method of the second unit (10) for producing containers (23) and / or the variation in said physical quantity, and modifying at least one of the control parameters of the first unit (2) for producing preforms, depending on the measurement of said physical quantity and / or of the variation in said physical quantity.

Description

[0001] DESCRIPTION

[0002] TITLE: Method for regulating a container production installation

[0003] technical field

[0004] The present invention relates to the field of molding containers such as bottles from preforms in polyethylene terephthalate (PET) and / or recycled polyethylene terephthalate (rPET), or in any other equivalent material such as polypropylene (PP) for example, which are blown into a mold.

[0005] State of the art

[0006] In the field of plastic bottle production, it is well known that a plastic blank, also called a parison or preform, can be obtained by means of a preform production unit from PET flakes, recycled PET, or any other equivalent thermoplastic, said preform production unit comprising at least one extruder producing molten material from said PET flakes and an injection molding device.

[0007] The PET flakes are heated and extruded in the extruder to form a viscous paste which feeds the injection molding device in which the preforms are produced, the heating, extrusion and injection stages being controlled by a control unit from various so-called pilot parameters such as the heating temperature of the flakes, the extrusion temperature, the extrusion speed, the injection pressure, the dwell time in the mold, the injection speed, the cooling time and the ejection speed of the preforms for example.

[0008] From these preforms, it is known to obtain containers, such as bottles for example, by means of a container production unit by blow molding or stretch blow molding of said preforms previously produced by the first unit, said second container production unit being positioned downstream of the first preform production unit.

[0009] The said container production unit includes at least one oven for heating the preforms and a mold consisting of two half-molds delimiting a molding cavity, the said preforms being heated in the oven and then positioned in the mold, with possibly a pre-blowing step, the said preform heating, pre-blowing and blowing steps being controlled by a control unit from various so-called control parameters such as the heating temperature of the preforms in the oven, the blowing pressure in the mold and / or the pre-blowing pressure and / or the pre-blowing flow rate and / or the speed of the drawing rod for example.

[0010] Furthermore, it is well known that the quality of the preforms obtained from the preform production unit can affect the organoleptic qualities of the foodstuffs

[0011] General food products, such as still water, contained in plastic containers made from said preforms. In this regard, document LIS2012 / 098153A1 is known.

[0012] According to document US2012 / 098153A1, if the process flow after the formation of the viscous paste obtained by heating PET and / or rPET flakes is interrupted to measure and evaluate the quality parameters of the viscous paste, the heat present in the recycling process is wasted and greater logistical efforts are required.

[0013] If the acetaldehyde content of the viscous is too high, which may be due to excessive shear and temperature during the recycling process, taste-neutral foodstuffs, for example still water, may be affected in terms of taste if these foodstuffs are filled into the plastic containers obtained from the preforms.

[0014] Since the quality of the plastic material introduced into the batch recycling process, particularly PET flakes, is subject to natural fluctuations, the process flow must be controlled until the viscous pulp is discharged to ensure compliance with a predetermined quality standard for the molten material. To this end, it is common practice to take samples of the viscous pulp as it exits the extruder or the recycled product and submit them to laboratory testing. This allows for process flow control and provides measurement results regarding acetaldehyde content, intrinsic viscosity, color, and / or the content of other contaminants in the molten material or recycled product. Such a plant for producing viscous pulp from recycled product is described, for example, in document DE 102005013701 A1.

[0015] Thus, document U S2012 / 098153A1 describes an installation for the continuous production of preforms for plastic containers using at least recycled polyester for food filling, comprising at least one upstream installation section producing melt, at least one injection molding installation section producing preforms, and an installation control system, where at least the upstream installation section producing melt and the injection molding installation section are interlocked at an interface to form a single installation unit. For deriving process modification strategies and / or preform qualification strategies, an inline measurement station including an evaluation device is provided at the interface for at least one melt quality parameter measured in the process flow.

[0016] However, beyond preserving the organoleptic qualities of the foodstuffs contained in the containers obtained from said preforms, the quality of the preforms obtained in the preform production unit is likely to also affect all or part of the steps of the manufacturing process of the containers from these preforms, which may lead to insufficient quality of the containers obtained, thus affecting the efficiency of the manufacturing installation of said containers.

[0017] Disclosure of the invention

[0018] General One of the aims of the invention is therefore to remedy all or part of these disadvantages by proposing a simple and inexpensive design process to ensure good quality of containers made from PET preforms and / or recycled PET, known as rPET.

[0019] To this end, and in accordance with the invention, a process is proposed for manufacturing thermoplastic containers in an installation comprising at least one first preform production unit from PET flakes, recycled PET, or any other equivalent thermoplastic, said first preform production unit comprising at least one extruder producing molten material from said PET flakes and an injection molding device, said PET flakes being heated and extruded in the extruder to form a viscous paste which feeds the injection molding device in which the preforms are produced, the heating, extrusion and injection steps being controlled by a control unit based on various parameters called control parameters such as the flake heating temperature, the extrusion temperature, the extrusion speed, the injection pressure, the dwell time in the mold,the injection speed, cooling time and ejection speed of the preforms, for example, and a second container production unit by blow molding or stretch blow molding of said preforms previously produced by the first unit, said second container production unit being positioned downstream of the first preform production unit and comprising at least one oven for heating the preforms and a mold consisting of two half-molds delimiting a molding cavity, said preforms being heated in the oven and then positioned in the mold, possibly with a pre-blowing step, said preform heating, pre-blowing and blowing steps being controlled by a control unit based on various control parameters such as the heating temperature of the preforms in the oven,the blowing pressure in the mold and / or the pre-blowing pressure and / or the pre-blowing flow rate and / or the speed of the drawing rod, for example, characterized in that it comprises at least the following steps:

[0020] - Measurement of at least one physical quantity of at least one preform or at least one container and / or of at least one physical quantity of at least one of the process steps of the second container production unit and / or of the variation of said physical quantity,

[0021] - Modification of at least one of the control parameters of the first preform production unit based on the measurement of said physical quantity and / or the variation of said physical quantity.

[0022] This measurement step may consist of:

[0023] - measure the blowing and / or pre-blowing curve in the mold of the second container production unit;

[0024] - measure the intrinsic viscosity of the preforms;

[0025] - measure the light absorption of preforms;

[0026] - measure the temperature of the preforms at the entrance and / or exit of the oven of the second container production unit;

[0027] - measure the dimensions of all or part of the preforms;

[0028] General - measure the variation of the crystallized zone around the injection point of the preforms; - measure the colorimetry of the preforms, said measurement preferably consisting of determining the chromatic space L, a, b called CIELAB;

[0029] - determine impurities and / or visual defects from an image of a preform recorded using a CCD sensor or similar;

[0030] - measure the wall thickness of said containers at the exit of the mold of the second container production unit at at least a determined height;

[0031] Furthermore, the measured physical quantity(ies) are recorded in the control unit of the second container production unit, which includes means for determining the modification of at least one of the control parameters of the first preform production unit as a function of the measurement of said physical quantity and / or the variation of said physical quantity, the modified control parameter(s) being transmitted to the control unit of the first preform production unit.

[0032] According to one embodiment, the measured physical quantity or quantities are recorded in the control unit of the second container production unit and then the said physical quantity or quantities are transmitted to the control unit of the first preform production unit which includes means for determining the modification of at least one of the control parameters of the first preform production unit as a function of the measurement of said physical quantity and / or the variation of said physical quantity.

[0033] According to another embodiment, the measured physical quantity or quantities are transmitted to a remote server which includes means for determining the modification of at least one of the control parameters of the first preform production unit as a function of the measurement of said physical quantity and / or the variation of said physical quantity, the modified control parameter or parameters being transmitted to the control unit of the first preform production unit by said remote server.

[0034] Another object of the invention relates to a computer program product comprising a sequence of instructions which, when the program is executed by a computer, leads the computer to implement the steps of the process according to the invention.

[0035] Another object of the invention relates to a data processing device comprising means of implementing the steps of the process according to the invention.

[0036] A final object of the invention relates to a computer-readable recording medium comprising instructions which, when executed by a computer, lead the computer to carry out the steps of the process according to the invention.

[0037] Brief description of the drawings

[0038] Other advantages and features will become clearer from the following description of several embodiments, given by way of non-limiting examples, of the process according to the invention, with reference to the accompanying drawings in which:

[0039] General[Fig. 1] is a schematic representation of a container manufacturing facility including a preform production unit and a container production unit from said containers.

[0040] [Fig. 2] is a schematic representation of a container production unit from preforms.

[0041] Method of embodying the invention

[0042] Throughout the description, the same numerical references designate the same elements. Furthermore, the different views are not necessarily drawn to scale.

[0043] With reference to Figure 1, an installation 1 is shown for the continuous production of thermoplastic containers comprising at least a first unit 2 for the production of preforms 3 from PET flakes or chips and / or recycled PET and / or any other equivalent thermoplastic, said containers, generally PET bottles, are blow molded, intended for filling with foodstuffs, sealed and packaged appropriately.

[0044] The said preform production unit 2 3 comprises at least one extruder 4 producing molten material (PET and / or rPET or similar), preferably with a molten material filtration device, and a preform injection molding device 5 from which the preforms 3 are discharged in batches or continuously and are transported, for example, in cooling sleeves, not shown in Figure 1, along a cooling zone 6.

[0045] Upstream of said preform production unit 2, installation 1 comprises, from upstream to downstream, a material supply unit 7, said material consisting of PET and / or rPET and / or similar, a material processing unit 8 and a material decontamination unit 9.

[0046] Incidentally, the installation 1 may include, in the preform production unit 2 3, between the extruder 4 and the preform molding device 5, a rejection and / or recycling device for the molten material, not shown in Figure 1.

[0047] Furthermore, downstream of said preform production unit 2, said installation according to the invention comprises a container production unit 10, a filler 11, and a labeler 12 and / or a packaging unit. Optionally, the installation 1 may also include a container rejection device, not shown in Figure 1, positioned between the container production unit 10 and the filler.

[0048] The said container production unit 10, with reference to figure 2, includes a blow molder 13 associated with a preform thermal conditioning oven 14 3.

[0049] More specifically, said container production unit 10 includes a preform feeding device 15 (for preforms 3) which are introduced into the container production unit 10 through an inlet E which communicates with an inlet zone of the furnace 14.

[0050] The furnace 14 includes heating means 16 for the preforms 3, which are arranged mainly or partly in a "U" shaped path extending from the inlet zone of the furnace 14 into which the preforms

[0051] General3 are brought by the feeding device 15 to an exit zone of the furnace 14 in the vicinity of which is arranged a first transfer device 17.

[0052] The first transfer device 17 is intended to transfer the thermally conditioned preforms 3 from the exit zone of the oven 14 to a zone, called the introduction zone, of the preforms 3 in the blow molder 13.

[0053] The said blower 13 comprises a carousel 18 equipped with a series of molding units 19 distributed circumferentially and associated means for blowing or stretch-blowing (not shown).

[0054] A molding unit 19 generally comprises two mold holders 20 which are mounted movably between an open position and a closed position, for example mounted movably in rotation relative to each other, and a mold 21 comprising at least two molding elements 21a, 21b each fixed in a detachable manner to an associated mold holder 20.

[0055] Furthermore, said container production unit 10 includes, near the blower outlet, a second transfer device 22 for evacuating the produced containers 23.

[0056] Thus, with reference to Figures 1 and 2, said first preform production unit 2 comprises at least one extruder 4 producing molten material from said PET flakes and an injection molding device 5, said PET flakes being heated and extruded in the extruder 4 to form a viscous paste which feeds the injection molding device 5 in which the preforms 3 are produced.

[0057] The heating, extrusion and injection stages are controlled by a control unit, not shown in the figures, based on various so-called control parameters such as the heating temperature of the flakes, the extrusion temperature, the extrusion speed, the injection pressure, the dwell time in the mold 21, the injection speed, the cooling time and the ejection speed of the preforms for example

[0058] The installation 1 according to the invention further comprises a second container production unit 10 by blow molding or stretch blow molding of said preforms 3 previously produced by the first unit 2, said second container production unit 10 being positioned downstream of the first preform production unit 3.

[0059] Said second unit 10 for the production of containers 23 comprises at least one oven 14 for heating the preforms 3 and a mold 21 consisting of two half-molds 21a, 21b delimiting a molding cavity, said preforms 3 being heated in the oven 14 and then positioned in the mold 21, possibly with a pre-blowing step

[0060] The preform heating, pre-blowing and blowing stages are controlled by a control unit from various so-called control parameters such as the preform heating temperature in the oven, the blowing pressure in the mold 21 and / or the pre-blowing pressure and / or the pre-blowing flow rate and / or the speed of the drawing rod for example.

[0061] The method for regulating the installation according to the invention comprises at least the following steps of measuring at least one physical quantity of at least one preform 3 or at least one container 23 and / or at least one physical quantity of at least one of the steps of the method of

[0062] Generalla second unit 10 of container production 23 and / or the variation of said physical quantity, and a step of modifying at least one of the control parameters of the first unit 2 of preform production as a function of the measurement of said physical quantity and / or the variation of said physical quantity.

[0063] It is understood that the step of measuring a physical quantity is carried out using appropriate sensors well known to those skilled in the art.

[0064] Thus, this measurement step may consist of:

[0065] - measure the blowing and / or pre-blowing curve in mold 21 of the second container production unit;

[0066] - measure the intrinsic viscosity of the preforms;

[0067] - measure the light absorption of preforms;

[0068] - measure the temperature of the preforms at the entrance and / or exit of the oven of the second container production unit;

[0069] - measure the dimensions of all or part of the preforms;

[0070] - measure the variation of the crystallized zone around the injection point of the preforms; - measure the colorimetry of the preforms, said measurement preferably consisting of determining the L, a, b chromatic space called CIELAB;

[0071] - determine impurities and / or visual defects from an image of a preform recorded using a CCD sensor or similar;

[0072] - measure the wall thickness of said containers at the exit of the mold of the second container production unit at at least a determined height;

[0073] Furthermore, the measured physical quantity(ies) are recorded in the control unit of the second container production unit 10 23 which includes means for determining the modification of at least one of the control parameters of the first preform production unit 2 3 as a function of the measurement of said physical quantity and / or the variation of said physical quantity, the modified control parameter(s) being transmitted to the control unit of the first preform production unit 2 3.

[0074] According to one embodiment, the measured physical quantity or quantities are recorded in the control unit of the second container production unit 10 23 and then the said physical quantity or quantities are transmitted to the control unit of the first preform production unit 2 which includes means for determining the modification of at least one of the control parameters of the first preform production unit 2 3 as a function of the measurement of said physical quantity and / or the variation of said physical quantity.

[0075] According to another embodiment, the measured physical quantity or quantities are transmitted to a remote server, not shown in the figures, which includes means for determining the modification of at least one of the control parameters of the first preform production unit 2 3 as a function of the measurement of said physical quantity and / or the variation of said physical quantity, the modified control parameter or parameters being transmitted to the control unit of the first preform production unit 2 3 by said remote server.

[0076] It will be observed that all the different steps of the process according to the invention are carried out by means of a computer program comprising a sequence of instructions which, when the program is executed by a computer, leads the computer to implement the steps of the process according to the invention. In this respect, the installation includes a data processing device comprising means for implementing the steps of the process according to the invention; in this case, it is the control unit or the remote server.

[0077] Furthermore, the computer program is recorded on a computer-readable recording medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the process according to the invention.

[0078] Finally, it is quite clear that the examples we have just given are only particular illustrations and in no way limiting as to the fields of application of the invention.

Claims

DEMANDS

1. A method for manufacturing containers (23) of thermoplastic materials in an installation (1) comprising at least one first unit (2) for producing preforms (3) from PET flakes, recycled PET, or any other equivalent thermoplastic, said first unit (2) for producing preforms comprising at least one extruder (4) producing molten material from said PET flakes and an injection molding device (5), said PET flakes being heated and extruded in the extruder (4) to form a viscous paste which feeds the injection molding device (5) in which the preforms (3) are produced, the heating, extrusion and injection steps being controlled by a control unit from various parameters called control parameters such as the flake heating temperature, the extrusion temperature, the extrusion speed, the injection pressure, the dwell time in the mold (21),the injection speed, cooling time and ejection speed of the preforms, for example, and a second container production unit (10) for producing containers (23) by blow molding or stretch blow molding of said preforms (3) previously produced by the first unit (2), said second container production unit (10) (23) being positioned downstream of the first preform production unit (2) (3) and comprising at least one oven (14) for heating the preforms (3) and a mold (21) consisting of two half-molds (21a, 21b) defining a molding cavity, said preforms (3) being heated in the oven (14) and then positioned in the mold (21), possibly with a pre-blow step, said preform heating (3), pre-blow and blow steps being controlled by a control unit based on various control parameters such as the heating temperature preforms in the oven (14),the blowing pressure in the mold (21) and / or the pre-blowing pressure and / or the pre-blowing flow rate and / or the speed of the drawing rod, for example, characterized in that it comprises at least the following steps of:, (i) Measurement of at least one physical quantity of at least one preform (3) or at least one container (23) and / or of at least one physical quantity of at least one of the process steps of the second container production unit (10) and / or of the variation of said physical quantity, ii) Modification of at least one of the control parameters of the first preform production unit (2) as a function of the measurement of said physical quantity and / or the variation of said physical quantity.

2. A method according to claim 1 characterized in that the step of measuring at least one physical quantity consists of measuring the blowing and / or pre-blowing curve in the mold (21) of the second container production unit (10).

3. A method according to any one of claims 1 or 2 characterized in that the step of measuring at least one physical quantity consists of measuring the intrinsic viscosity of the preforms (3).

4. A method according to any one of claims 1 to 3 characterized in that the step of measuring at least one physical quantity consists of measuring the light absorption of the preforms (3).

5. A method according to any one of claims 1 to 4 characterized in that the step of measuring at least one physical quantity consists of measuring the temperature of the preforms (3) at the inlet and / or outlet of the oven (14) of the second container production unit (10).

6. A method according to any one of claims 1 to 5 characterized in that the step of measuring at least one physical quantity consists of measuring the dimensions of all or part of the preforms (3).

7. A method according to any one of claims 1 to 6 characterized in that the step of measuring at least one physical quantity consists of measuring the variation of the crystallized zone around the injection point of the preforms (3).

8. A method according to any one of claims 1 to 7 characterized in that the step of measuring at least one physical quantity consists of measuring the colorimetry of the preforms (3).

9. A method according to claim 8 characterized in that the step of measuring at least one physical quantity consists of determining the L, a, b chromatic space called CIELAB.

10. A method according to any one of claims 1 to 9 characterized in that the measurement step of at least one physical quantity consists of determining visual impurities and / or defects from an image of a preform (3) recorded by means of a CCD sensor or similar.

11. A method according to any one of claims 1 to 10 characterized in that the step of measuring at least one physical quantity consists of measuring the wall thickness of said containers (23) at the exit of the mold (21) of the second unit (10) for producing containers (23) at at least a determined height. General

12. A method according to any one of claims 1 to 11 characterized in that the measured physical quantity or quantities are recorded in the control unit of the second container production unit (10) which includes means for determining the modification of at least one of the control parameters of the first preform production unit (2) as a function of the measurement of said physical quantity and / or the variation of said physical quantity, the modified control parameter or parameters being transmitted to the control unit of the first preform production unit (3) (2).

13. A method according to any one of claims 1 to 11 characterized in that the measured physical quantity or quantities are recorded in the control unit of the second container production unit (10) and then the said physical quantity or quantities are transmitted to the control unit of the first preform production unit (2) (3) which includes means for determining the modification of at least one of the control parameters of the first preform production unit (2) as a function of the measurement of said physical quantity and / or the variation of said physical quantity.

14. A method according to any one of claims 1 to 11 characterized in that the measured physical quantity or quantities are transmitted to a remote server which includes means for determining the modification of at least one of the control parameters of the first preform production unit (2) (3) as a function of the measurement of said physical quantity and / or the variation of said physical quantity, the modified control parameter or parameters being transmitted to the control unit of the first preform production unit (2) by said remote server.

15. Product computer program comprising a sequence of instructions which, when the program is executed by a computer, causes the computer to carry out the steps of the process according to any one of claims 1 to 14.

16. Data processing device comprising means for carrying out the steps of the process according to any one of claims 1 to 14.

17. A computer-readable recording medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the process according to any one of claims 1 to 14.

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