HEAT TREATMENT UNIT FOR PREFORMS WITH A SAFETY SYSTEM FOR DETECTING RADIATION LEAKS

Description

[0001] The present invention relates to a preform heat treatment unit of a container manufacturing installation, of the type comprising an enclosure within which the preforms pass along a predefined path and at least one emitting wall comprising at least one emitting element of monochromatic or pseudo-monochromatic electromagnetic radiation arranged to emit said radiation towards the preforms circulating in the enclosure, said enclosure being closed at least in part by a fairing arranged to prevent said radiation from passing through the fairing to the outside of the enclosure.

[0002] Such a heat treatment unit, or furnace, is generally equipped with a plurality of heating elements arranged to emit heat towards synthetic material preforms passing through the heat treatment unit in order to apply a heating profile to these preforms and enable their subsequent deformation, for example by stretch blow molding, so as to produce containers from the preforms.

[0003] The use of monochromatic or pseudo-monochromatic electromagnetic radiation emitting elements, or laser emitters, as heating elements is particularly beneficial in such a heat treatment unit because such elements offer superior optical efficiency and accuracy compared to other types of heating elements, such as halogen incandescent lamps, enabling faster and more selective heating of preforms.

[0004] However, the use of such laser emitters requires special precautions due to the danger posed by the emitted radiation to operators working around the heat treatment unit. Indeed, the radiation is emitted in the infrared range and is invisible to the naked eye, and can therefore easily cause serious injuries not only to the eyes but also to the skin of operators who may not be aware of their exposure to this radiation.

[0005] To prevent this exposure, the enclosure containing the preforms will be contained as much as possible to minimize radiation leakage. For example, the enclosure will be closed with a shroud comprising walls designed to block radiation. These walls will enclose the enclosure and the emission components, leaving at least one opening for the entry and exit of preforms. At least some of these walls will be removable to allow access to the enclosure for handling and other operations when the heat treatment unit is shut down and the emission components are not emitting radiation.

[0006] Before commissioning the heat treatment unit, it is essential to ensure that all removable panels are in place to prevent radiation leaks at these locations. An operator is typically responsible for verifying that all removable panels are present before authorizing the start-up of the heat treatment unit. However, such a verification is prone to errors and oversights by the operator.

[0007] During operation, it is also important to ensure that there are no radiation leaks, particularly at the preform passage opening or due to a damaged wall outside the enclosure. Since this radiation is not visible to the naked eye, any radiation leakage is difficult to detect.

[0008] One of the aims of the invention is to overcome this drawback by providing a heat treatment unit in which any radiation leakage can be easily detected.

[0009] To this end, the invention relates to a thermal processing unit of the aforementioned type, further comprising at least one safety system including at least one image acquisition device disposed outside the fairing and at least one image processing device for images acquired by said image acquisition device, said image acquisition device acquiring images at least in the near-infrared range, the images acquired by said image acquisition device being capable of showing radiation emitted outside the fairing, the processing device being configured to identify the presence of a radiation leak outside the enclosure if at least one image acquired by said image acquisition device shows radiation emitted outside the fairing.

[0010] Using a near-infrared imaging device and an image processing device, it is easy to determine if the enclosure has a radiation leak and where the leak occurs. By selecting a suitable imaging device, it is also possible to easily verify that all removable panels are in place when the heat treatment unit is switched on.

[0011] The heat treatment unit according to the invention may further comprise one or more of the following features, considered alone or in any technically feasible combination: said fairing includes at least one opening for the entry and / or exit of preforms into and / or out of the enclosure, at least one image acquired by said image acquisition device showing at least said opening; the safety system further includes an alarm device arranged to issue an alarm to an operator and / or to stop or prevent the operation of the heat treatment unit if the treatment device identifies the presence of a radiation leak outside the enclosure; the alarm device is triggered when the radiation level detected by the treatment device exceeds the maximum permissible exposure as defined in IEC 60825-1 and / or the protected exposure limit as defined in IEC 60825-4;the fairing includes at least one removable wall disposed in a predefined area of ​​the enclosure, the image acquisition device being further arranged to acquire images in the visible range, said image acquisition device being arranged to acquire at least one image of said predefined area and the processing device being configured to detect the presence or absence of said removable wall in said acquired image; the removable wall includes at least one identification element, the image acquisition device being arranged to acquire at least one image of said identification element, said processing device being configured to detect the presence of said identification element in said acquired image; the removable wall delimits at least part of the opening;the image acquisition device includes at least one camera capturing images at least in the near-infrared range, said camera being oriented so that at least part of the fairing extends within the frame of said camera; the security system includes a plurality of image acquisition devices arranged to each acquire at least one image of a different area of ​​the fairing, the processing device being configured to identify the presence of a radiation leak outside the enclosure if at least one image acquired by said image acquisition devices shows radiation emitted outside the fairing;The image acquisition device is mobile relative to the enclosure and / or includes at least one moving element such that the image acquisition device acquires images of a plurality of areas of the fairing by moving relative to the enclosure to detect the presence or absence of radiation leaks in said areas.

[0012] The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the drawings in which: [ Fig.1 ] - there [ Fig.1 ] is a schematic perspective representation of part of a heat treatment unit according to the invention, and [ Fig.2 ] - there [ Fig.2 ] is a schematic perspective representation of the heat treatment unit of the [ Fig.1 ] without the removable partitions enclosing the space.

[0013] With reference to Figs. 1 And 2, we describe a heat treatment unit 1, or furnace, of a container manufacturing plant using preforms 2.

[0014] The heat treatment unit comprises an enclosure 4 delimited by two walls 6 ([ Fig.2 ]), at least one of which is an emitting wall comprising at least one emitting element of monochromatic or pseudo-monochromatic electromagnetic radiation. The preforms 2 circulate within the enclosure 4 along a predefined circulation path T defining a longitudinal direction. The walls 6 are spaced from each other along a transverse direction substantially perpendicular to the longitudinal direction so as to extend on either side of the circulation path T. On the Figs. 1 And 2The path T has been represented as rectilinear, but it is understood that it could be curved in certain configurations of the container manufacturing installation. Alternatively, the preforms 2 circulate within the enclosure 4 along a predefined circular path T. The heat treatment unit includes a gripping and movement system 8 for the preforms 2 along the circulation path T between the walls 6. The preforms 2 are held so that their respective axes extend in an upward direction substantially perpendicular to the longitudinal and transverse directions. In other words, the upward direction corresponds to the height of the preforms 2 and the height of the walls 6. The gripping system can be arranged so that the preforms 2 rotate about their axis as they circulate along the path T.

[0015] The emitting element comprises, for example, a plurality of monochromatic or pseudo-monochromatic electromagnetic radiation sources. More specifically, the emitting element is, for example, a laser emitter, and the radiation sources are laser chips arranged to emit laser radiation in the infrared range along an emission direction substantially parallel to the transverse direction. The radiation sources are, for example, arranged side by side and one above the other on a support so as to form rows of radiation sources extending along the longitudinal direction.

[0016] Such emission elements are described for example in document FR 3 124 030 and a person skilled in the art can refer to this document for further details, particularly with regard to the structure of each radiation source, the arrangement of radiation sources on a support, the connection of radiation sources to each other and the cooling of heating elements.

[0017] The emitting wall 6 comprises, for example, a plurality of emission elements as described above, the emission elements being distributed, for example, at least along the longitudinal direction on the wall 6 and, alternatively or in addition, at least along the elevation direction on the wall 6.

[0018] According to one embodiment, the two walls 6 are emitting walls as described above. It should be noted that each wall 6 may also include reflective elements arranged to reflect the radiation from the emitting elements of the opposite wall. Such an enclosure arrangement is described, for example, in document FR 3 124 030, and those skilled in the art may refer to it.

[0019] Thus, due to the large number of emitting elements and reflections within the enclosure, it is understandable that radiation can easily be emitted outside the enclosure and pose a risk to operators working around the heat treatment unit. The problem arises particularly at the inlet and outlet of enclosure 4, that is, where the preforms 2 enter and exit the enclosure. Indeed, enclosure 4 must be open in these areas to allow passage for the preforms 2.

[0020] According to one embodiment, at least one airlock 10 is provided at the entrance and / or exit of enclosure 4. As shown in the [ Fig.2 [ ] Such an airlock 10 is located downstream of an opening 12 allowing the entry of preforms 2 into the enclosure 4 and upstream of the emitting walls 6, and / or upstream of the opening allowing the exit of preforms 2 from the enclosure 4 and downstream of the emitting walls 6, the upstream and downstream positions being defined according to the direction of flow of preforms 2 within the enclosure 4. Such an airlock 10 is designed to limit, or even eliminate, the radiation likely to pass through the opening associated with this airlock 10 by forming a radiation trap inside the airlock. To this end, the airlock 10 is, for example, equipped with shields 14 extending along the predefined path T of the preforms 2 as they pass through the airlock 10, for example between successive preforms 2, in order to block the radiation directed towards the opening 12.These shields are, for example, rotatable to form turnstiles through which the preforms 2 must pass before and / or after passing between the emitting walls 6. Such airlocks 10 are described, for example, in document WO 2011 / 110791, so they will not be described in further detail here. Those skilled in the art can refer to this document for more details on the implementation and arrangement of such airlocks 10 in a heat treatment unit 1.

[0021] As depicted on the [ Fig.1 The enclosure 4 of the heat treatment unit 1 is further enclosed within a casing 16 arranged to prevent radiation emitted within the enclosure 4 from escaping it. Thus, the casing 16 is designed to isolate the enclosure 4, as much as possible, from the room in which the heat treatment unit 1 is located, so that operators can move around the heat treatment unit 1 without risk of exposure to radiation emitted within the enclosure 4. The casing 16 closes off the enclosure 4 along the predefined path T, at least on both sides of the enclosure 4 in the transverse direction and at least above the enclosure 4 in the vertical direction Z. To this end, the casing 16 extends along the walls 6, on their outer side, and covers the space between the walls 6 as well as the walls 6 above the enclosure 4.On the lower side of the enclosure 4, the fairing 16 includes, for example, a slot-shaped opening to allow passage for the gripping and movement system 8 of the preforms 2 between the inside of the enclosure 4 and the outside. The fairing 16 further defines the opening 12 for the entry and / or exit of the preforms 2 into and out of the enclosure 4; that is to say, this opening or these openings 12 are made in the fairing. When one or more airlocks 10 are provided, the fairing 16 also surrounds them, as shown in the [ . Fig.1 ].

[0022] In one embodiment, the fairing 16 comprises at least one removable partition 18 forming part of the fairing 16. A removable partition 18 is understood to mean that the removable partition 18 can be reversibly separated from the rest of the fairing 16 and the enclosure 4, for example, to provide access to the enclosure 4 and to the components extending within it for maintenance or other purposes. For this purpose, the removable partition 18 is, for example, mounted on a housing of the fairing 16 by means of reversible fasteners that allow the removable partition 18 to be attached to the housing and removed from the housing. The removable partition 18 extends between an inner face 20, facing inwards towards the enclosure 4 when the removable partition 18 is mounted on the housing, and an outer face 22, opposite the inner face 20 and facing outwards towards the enclosure 4.The removable partition 18 is arranged to prevent the passage of radiation emitted by the emitting elements of the inner face 20 to the outer face 22 of the removable partition 18. For this purpose, the removable partition 18 can be made of a material that prevents this passage, for example, by absorbing the radiation, or the inner face 20 can be coated with such a material. Alternatively, the material can be a radiation-reflective material. The removable partition 18, for example, conforms to passive laser shields as defined by IEC 60825-4.

[0023] The removable partition 18 is positioned within a predefined area of ​​the enclosure 4. This predefined area corresponds, in particular, to a zone in which the radiation emitted by the emitting elements is likely to escape from the enclosure 4 in the absence of the removable partition 18, and is blocked by it when the removable partition 18 is mounted on the rest of the fairing 16. Thus, the predefined area extends, for example, to an edge of the opening 12 of the enclosure, or along a portion of the emitting partition 6, or opposite it. In other words, the removable partition 18 defines, for example, at least one edge of the opening 12 of the enclosure 4 and / or extends opposite one or more emitting elements in the transverse direction.

[0024] According to a particularly advantageous embodiment and as shown in the [ Fig.1 The fairing 16 is formed by an assembly of removable panels 18, meaning that the fairing 16 is entirely demountable. Each removable panel 18 is positioned in a predefined area of ​​the enclosure 4, and their assembly allows the enclosure 4 to be completely closed except in areas where it must be open, as described previously. It is thus understood that when all the removable panels 18 are mounted on the enclosure 4, radiation leakage is only likely to occur at the openings provided in the enclosure 4, and that the enclosure 4 can be equipped with features to reduce this risk of leakage at the openings, such as the airlocks 10 described previously.It is also understood that the absence of a removable partition 18 in the corresponding predefined area can lead to radiation leakage at the level of this predefined area and cause a risk to operators working in relation to this predefined area when the heat treatment unit is in operation.

[0025] The heat treatment unit according to the invention includes a safety system comprising at least one image acquisition device 24 disposed outside the enclosure 4, facing at least a portion of the shroud 16 and arranged to acquire at least one image of at least that portion of the shroud 16. The safety system further includes an image processing device 26 for the images acquired by the image acquisition device 24, arranged to determine whether or not there is any radiation leakage from the enclosure 4 based on the acquired image. Thus, the safety system makes it possible to verify that the radiation emitted by the emitting wall(s) 6 does not escape from the enclosure 4, i.e., that it is not stopped by the shroud 16, during the operation of the heat treatment unit.In one embodiment, the safety system further includes an alerting device arranged to issue an alarm to an operator and / or to stop or prevent the operation of the heat treatment unit if the treatment device 26 detects the presence of a radiation leak. In this way, it is ensured that the heat treatment unit does not operate when a radiation leak outside the enclosure 4 is detected, or at least that operators working around the heat treatment unit are warned of the presence of a leak and can take appropriate action.

[0026] The image acquisition device 24 is arranged outside the enclosure 4 and acquires images from the external side of the fairing 16, as shown in the [ Fig.1 ].

[0027] The image acquisition device 24 includes, for example, at least one camera capturing images at least in the near-infrared range, the camera being oriented so that at least a portion of the fairing 16 extends within the camera's frame. Near-infrared is understood to mean a wavelength approximately between 0.7 µm and 1.6 µm.

[0028] More specifically, the image acquisition device 24 is positioned so that at least one aperture 12 is within the frame of the acquired images. Indeed, the inlet and / or outlet aperture 12 of the preforms 2 into and out of the enclosure 4 is the location where radiation leakage is most likely to occur, even when shields 14 as described previously are provided. When the same aperture 12 allows both the inlet and outlet of the preforms, or when the inlet and outlet apertures are adjacent, a single image acquisition device 24 can be used to detect the presence of leakage at the aperture(s) 12. When the inlet and outlet apertures are separate, one image acquisition device 24 per aperture is preferably provided to monitor for leakage at each of the apertures 12.The image acquisition device(s) 24, or additional image acquisition devices 24, can also be positioned to detect the possible presence of leakage in other areas of the fairing 16, in particular at the removable walls 18 extending along the emitting walls 6, as shown in the [. Fig.1 This embodiment is advantageous, in particular for detecting if a removable partition 18 is damaged and allows radiation to pass from the inner face 20 to the outer face 22.

[0029] In one embodiment, the image acquisition device 24 is further configured to acquire images in the visible spectrum of at least one predefined area in which a removable partition 18 must be located. The processing device 26 can then also be used to determine whether or not the removable partition 18 is present in the acquired image of the predefined area. Thus, the safety system makes it possible to verify that the removable partition 18 is correctly positioned, for example, before starting the heat treatment unit 1. In one embodiment, the alarm device is also configured to send an alarm to an operator and / or to stop or prevent the operation of the heat treatment unit if the processing device detects the absence of the removable partition 18 in a predefined area.In this way, we ensure that the heat treatment unit only operates when the removable wall 18 has been properly put in place.

[0030] When the heat treatment unit 1 comprises several movable walls 18, in particular movable walls 18 adjacent to each other, the image acquisition device 24 is arranged to acquire one or more images of several movable walls 18, for example by providing that the camera frame encompasses several predefined areas so that the acquisition of a single image by the camera makes it possible to detect the presence of a radiation leak in all these predefined areas, or even the presence or absence of all these movable walls 18. Alternatively or in addition, the image acquisition device 24 is movable relative to the enclosure 4 and / or includes a movable part, such as a mirror, so that the image acquisition device can acquire images of a plurality of predefined areas to detect the presence or absence of leaks in these areas, or even the presence or absence of movable walls 18 in these predefined areas.The image acquisition device 24 is thus, for example, mobile and rotatable so as to scan several predefined areas and acquire at least one image for each of these predefined areas. The processing device 26 is then configured to determine in each image the presence or absence of radiation leakage in each of the predefined areas.

[0031] The image processing device 26 is configured to determine the presence or absence of radiation outside the enclosure 4 by analyzing the images acquired by the image acquisition device(s). Such a determination is based, for example, on an analysis of the image's colorimetry; an area of ​​the image where radiation is present appears, for example, to be brighter than an area where no radiation is present. In one embodiment, the processing device 26 can be configured to process the acquired images to highlight any radiation and / or to determine its intensity.Thus, for example, the intervention of the alert device may be triggered when the detected radiation level exceeds the maximum permissible exposure (MPE) as defined in IEC 60825-1 and / or the protected exposure limit (PEL) as defined in IEC 60825-4.

[0032] The image processing device 26 also makes it possible to determine the area where a radiation leak is occurring, so that operators can take the necessary measures to eliminate this radiation leak. The effectiveness of these measures can be determined by acquiring a new image of the affected area and using the processing device 26 to determine if a leak is still present in that area.

[0033] When the security system is also configured to detect the presence or absence of one or more movable partitions 18 in one or more predefined zones, the image processing device 26 is, for example, configured to compare the acquired image(s) with an image in which the movable partition(s) 18, corresponding to the predefined zone(s) whose images are acquired by the image acquisition device 24, are all present. Thus, the image processing device makes it easy to determine whether a movable partition 18 is not present in an image as soon as there is a difference between the processed image and the image in which all the movable partitions 18 are present.

[0034] Alternatively or in addition, each removable partition 18 may include at least one identification element 28, the image of which is acquired by the image acquisition device 24 during the verification of the presence of the removable partition 18. The image processing device 26 is then configured to detect the presence or absence of the identification element 28 in the image acquired by the image acquisition device 24 in order to determine whether the removable partition 18 is present in the predefined area. The detection of the identification element 28 can, in addition to verifying the presence or absence of the removable partition 18, determine whether the detected removable partition 18 is indeed the one that should be placed in the predefined area whose image was acquired. In fact, the identification element 28 makes each removable partition 18 distinct from the others and allows each removable partition 18 to be individually associated with a predefined area.The detection of the identification element 28 can be done in addition to, or instead of, the image comparison described above, as locating the identification element in an image can be done more simply than image comparison, particularly from a software perspective. The identification element 28 is, for example, formed by a QR code, as shown in the [. Fig.1 ], or by any other suitable identifying element, such as a barcode or other. The identifying element 28 is applied to the outer face 22 of the removable partition 18.

[0035] In the figures, each image acquisition device 24 is associated with an image processing device 26. It is understood, however, that the same image processing device 26 can be used for several image acquisition devices 24. Alternatively, the image acquisition devices 24 and image processing devices 26 can be combined to form part of a single system, for example within the same housing.

[0036] As previously stated, the detection of the presence of a leak, or even of the presence of the removable walls 18, is triggered for example before any production of the heat treatment unit 1 and this production is prevented as soon as at least one radiation leak outside the enclosure 4 is detected.

Claims

1. Heat treatment unit (1) for preforms (2) of a container manufacturing plant, said heat treatment unit comprising an enclosure (4) within which the preforms (2) travel along a predefined path (T) and at least one emitting wall (6) comprising at least one monochromatic or pseudo-monochromatic electromagnetic radiation emitting element arranged to emit said radiation towards the preforms (2) circulating in the enclosure (4), said enclosure (4) being closed at least in part by a shielding (16) arranged to prevent said radiation from passing through the shielding (16) towards the outside of the enclosure (4), the heat treatment unit being characterized in that it further comprises at least one safety system comprising at least one image acquisition device (24) arranged outside the shielding (16) and at least one image processing device (26) processing the images acquired by said image acquisition device (24), said image acquisition device (24) acquiring images at least in the near infrared domain, the images acquired by said image acquisition device (24) being able to show radiation emitted outside the shielding (16), the processing device (26) being configured to identify the presence of a radiation leak out of the enclosure (4) if at least one image acquired by said image acquisition device (24) shows radiation emitted outside the shielding (16).

2. Heat treatment unit according to Claim 1, wherein said shielding (16) has at least one opening (12) for entry and / or exit of the preforms (2) into and / or out of the enclosure (4), at least one image acquired by said image acquisition device (24) showing at least said opening (12).

3. Heat treatment unit according to Claim 1 or 2, wherein the safety system further comprises an alert device arranged to emit an alarm destined for an operator and / or to stop or prevent the operation of the heat treatment unit if the processing device (26) identifies the presence of a radiation leak out of the enclosure (4).

4. Heat treatment unit according to Claim 3, wherein the alert device is triggered when the radiation level detected by the processing device (26) exceeds the maximum permissible exposure (MPE) as defined in the standard IEC 60825-1 and / or the protective exposure limit (PEL) as defined in the standard IEC 60825-4.

5. Heat treatment unit according to any one of Claims 1 to 4, wherein the shielding (16) comprises at least one removable wall (18) arranged in a predefined zone of the enclosure (4), the image acquisition device (24) being further arranged to acquire images in the visible domain, said image acquisition device (24) being arranged to acquire at least one image of said predefined zone and the processing device (26) being configured to detect the presence or absence of said removable wall (18) in said acquired image.

6. Heat treatment unit according to Claim 5, wherein the removable wall (18) comprises at least one identification element (28), the image acquisition device (24) being arranged to acquire at least one image of said identification element (28), said processing device (26) being configured to detect the presence of said identification element (28) in said acquired image.

7. Heat treatment unit according to Claim 5 or 6 when dependent on claim 2, wherein the removable wall (18) delimits at least a portion of the opening (12).

8. Heat treatment unit according to any one of Claims 1 to 7, wherein the image acquisition device (24) comprises at least one camera capturing images at least in the near-infrared domain, said camera being oriented such that at least one portion of the shielding (16) extends within the frame of said camera.

9. Heat treatment unit according to any one of Claims 1 to 8, wherein the safety system comprises a plurality of image acquisition devices (24) arranged to each acquire at least one image of a different zone of the shielding (16), the processing device (26) being configured to identify the presence of a radiation leak out of the enclosure (4) if at least one image acquired by said image acquisition devices (24) shows radiation emitted outside the shielding (16).

10. Heat treatment unit according to any one of Claims 1 to 9, wherein the image acquisition device (24) is movable relative to the enclosure and / or comprises at least one movable member such that the image acquisition device (24) acquires images of a plurality of zones of the shielding (16) by moving relative to the enclosure (4) so as to detect the presence or absence of radiation leaks in said zones.