Unit for heat treatment of preforms comprising safety system for detecting radiation leaks

Abstract

A unit for heat treatment of preforms including a safety system for detecting radiation leaks. A heat treatment unit (1) comprises: a housing (4) within which a preform (2) travels along a predetermined path (T); and at least one emission wall (6) comprising at least one emission element for emitting electromagnetic radiation, the housing (4) being at least partially closed by a shield (16). The heat treatment unit comprises at least one safety system comprising image acquisition means (24) arranged outside the shroud (16), and processing means (26) for processing the image, the acquired image being capable of displaying radiation emitted outside the shroud (16), the processing means (26) being configured to determine the radiation emitted outside the shroud (16) if the image acquired by the image acquisition means (24) displays radiation. If so, it is detected that there is a leakage of radiation outside the housing (4).

Description

Technical Field

[0001] The present invention relates to a heat treatment unit for heat treating preforms of a container manufacturing device, the heat treatment unit comprising a shell, the preforms travelling along a predetermined path in the shell, the heat treatment unit further comprising at least one emitting wall, the emitting wall comprising at least one emitting element for emitting monochromatic or pseudo-monochromatic electromagnetic radiation, the emitting element being arranged to emit radiation to the preforms passing through the shell, the shell being at least partially enclosed by a shield, the shield being arranged to prevent radiation from passing through the shield to the outside of the shell. Background Art

[0002] Such a heat treatment unit or furnace is usually equipped with a plurality of heating elements which are arranged to emit heat in the direction of the synthetic material preforms travelling in the heat treatment unit in order to impose a heating profile on these preforms and to allow their subsequent deformation, for example by stretch blow moulding, in order to produce containers from the preforms.

[0003] The use of emitting elements or laser emitters emitting monochromatic or pseudo-monochromatic electromagnetic radiation as heating elements is particularly advantageous in such a heat treatment unit, since such elements offer higher efficiency and optical precision than other types of heating elements, such as halogen incandescent lamps, which allows faster and more selective heating of the preforms.

[0004] However, the use of such laser emitters must be accompanied by special precautions, since the emitted radiation is dangerous for operators moving around the thermal treatment unit. In fact, the radiation is emitted in the infrared range, invisible to the naked eye, and can therefore easily cause serious damage not only to the eyes but also to the skin of the operator, without the operator necessarily being aware that they are exposed to this radiation.

[0005] To prevent this exposure, it is proposed to confine the housing in which the preforms travel as much as possible, so as to limit the radiation leakage outside the housing to the greatest extent possible. To this end, it is proposed, for example, to close the housing with a shield comprising walls arranged to block the passage of radiation, these walls enclosing the housing and the emitting element, while leaving at least one opening for the preforms to enter and exit the housing. At least some of these walls are removable, so as to leave access to the housing for loading and unloading and other operations when the thermal treatment unit is stopped and the emitting element is not emitting radiation.

[0006] Therefore, before any thermal treatment unit is put into operation, it should be ensured that all removable walls are present to avoid radiation leakage at these walls. The operator is usually responsible for checking that all removable walls are indeed present before allowing the thermal treatment unit to be started. However, this check may be subject to error and the operator may forget.

[0007] During operation, it should also be ensured that no radiation leaks out of the enclosure, in particular not at the through openings of the preforms or due to damaged walls. Since this radiation is invisible to the naked eye, it is difficult to detect any radiation leakage. Summary of the invention

[0008] One of the objects of the present invention is to overcome this drawback by proposing a thermal treatment unit in which any radiation leakage can be easily detected.

[0009] To this end, the present invention relates to a thermal treatment unit of the above-mentioned type, which also includes at least one safety system, the safety system including at least one image acquisition device and at least one processing device, the image acquisition device is arranged outside the protective cover and the processing device is used to process the image acquired by the image acquisition device, the image acquisition device acquires images within at least the near-infrared range, the images acquired by the image acquisition device can display radiation emitted outside the protective cover, and the processing device is configured to identify the presence of radiation leakage outside the housing if at least one image acquired by the image acquisition device shows radiation emitted outside the protective cover.

[0010] By using an image acquisition device in the near infrared range and an acquired image processing device, it is possible to easily determine whether there is a radiation leak from the housing and the area in which the radiation leak occurs. By selecting a suitable image acquisition device, it is also possible to check in a simple manner whether all removable walls are actually present when starting the thermal treatment unit.

[0011] The heat treatment unit according to the invention may also include one or more of the following features, considered alone or in any combination that is technically feasible:

[0012] - the shield comprises at least one opening for the preform to enter and / or leave the housing, the at least one image acquired by the image acquisition device showing at least said opening;

[0013] - the safety system further comprises an alarm device arranged to warn an operator and / or to stop or prevent operation of the thermal treatment unit if the treatment device identifies the presence of radiation leakage outside the enclosure;

[0014] - when the radiation level detected by the processing device exceeds the maximum permissible exposure value as defined in the CEI 60825-1 standard and / or the protective exposure limit as defined in the CEI 60825-4 standard, the alarm device is triggered;

[0015] - the shield comprises at least one removable wall arranged in a predetermined area of ​​the housing, the image acquisition device is further arranged to acquire images in the visible light range, the image acquisition device is arranged to acquire at least one image of the predetermined area, the processing device is configured to detect whether the removable wall is present in the acquired images;

[0016] - the removable wall comprises at least one identification element, the image acquisition device is arranged to acquire at least one image of the identification element, the processing device being configured to detect whether the identification element is present in the acquired image;

[0017] - a removable wall defining at least a portion of said opening;

[0018] - the image acquisition means comprises at least one camera, the camera capturing images in at least the near infrared range, the camera being oriented so that at least a portion of the shield extends within the range of the camera;

[0019] - the safety system comprises a plurality of image acquisition devices, each image acquisition device being arranged to acquire at least one image of a different region of the shield, the processing device being configured to identify the presence of radiation leakage outside the enclosure if at least one image acquired by the image acquisition device shows radiation emitted outside the shield;

[0020] The image acquisition device is movable relative to the housing and / or comprises at least one movable element, so that the image acquisition device acquires images of multiple areas of the shield by moving relative to the housing to detect whether there is radiation leakage in the multiple areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The invention will emerge more clearly from a reading of the following description given purely by way of non-limiting example and with reference to the accompanying drawings, in which:

[0022] Figure 1 : Figure 1 is a schematic perspective view of a portion of a heat treatment unit according to the invention, and

[0023] Figure 2 : Figure 2 yes Figure 1 Schematic perspective view of a heat treatment unit without the removable walls of the enclosing housing. DETAILED DESCRIPTION

[0024] Reference Figure 1 and Figure 2 A heat treatment unit 1 or a furnace of a container manufacturing plant for manufacturing containers from preforms 2 is described.

[0025] The heat treatment unit comprises two walls 6 ( Figure 2 ) is defined by a housing 4, wherein at least one wall is an emitting wall, and the emitting wall includes at least one emitting element for emitting monochromatic or pseudo-monochromatic electromagnetic radiation. The preform 2 passes along a predetermined passage path T defined in a longitudinal direction in the housing 4. The walls 6 are spaced apart from each other in a transverse direction substantially perpendicular to the longitudinal direction so as to extend on both sides of the passage path T. Figure 1 and Figure 2 , the path T is shown as a straight line, but it should be understood that in some configurations of the container manufacturing device, the path can be curved. Therefore, as a variant, the preform 2 passes along a circular predetermined passage path T in the housing 4. The thermal treatment unit includes a system 8 for clamping and moving the preform 2 along the passage path T between the walls 6. The preforms 2 are more specifically held so that their respective axes extend in an upright direction that is substantially perpendicular to the longitudinal and transverse directions. In other words, the upright direction corresponds to the height of the preform 2 and the height of the wall 6. In a known manner, the clamping system can be arranged so that the preform 2 rotates around its axis when traveling along the path T.

[0026] 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, the radiation source being a laser chip, which is arranged to emit laser radiation in the infrared range in an emission direction substantially parallel to the transverse direction. The radiation sources are arranged, for example, side by side and one above the other on a support so as to form a row of radiation sources extending in the longitudinal direction.

[0027] Such an emitting element is described, for example, in document FR 3 124 030, to which a person skilled in the art may refer for more details, in particular as to the structure of each radiation source, their arrangement on the support, their connection to one another and the cooling of the heating element.

[0028] The emitting wall 6 comprises, for example, a plurality of emitting elements as described above, which are distributed on the wall 6 at least in the longitudinal direction, or as a variant or as a complement, at least in the vertical direction.

[0029] According to one embodiment, both walls 6 are emitting walls as described above. It should be noted that each wall 6 may also include reflective elements arranged to reflect radiation from the emitting elements of the opposite wall. Such a housing arrangement is described, for example, in document FR 3 124 030, to which a person skilled in the art may refer.

[0030] Therefore, due to the large number of emitting elements and reflections inside the housing, it is understandable that radiation can easily be emitted outside the housing, posing a risk to operators moving around the thermal treatment unit. This problem arises in particular at the inlet and outlet of the housing 4, i.e. at the locations where the preforms 2 enter and leave the housing. In fact, the housing 4 must be open in these areas in order to leave a passage for the preforms 2.

[0031] According to one embodiment, at least one compartment 10 is arranged at the inlet and / or outlet of the housing 4. Figure 2As shown in , such a compartment 10 is arranged downstream of an opening 12 allowing the preforms 2 to enter the housing 4 and upstream of the emission walls 6, and / or upstream of an opening allowing the preforms 2 to leave the housing 4 and downstream of the emission walls 6, the upstream and downstream being defined according to the direction of passage of the preforms 2 in the housing 4. Such a compartment 10 is arranged to limit, or even eliminate, the radiation that may pass through the opening associated with this compartment 10 by forming a radiation trap inside the compartment. To this end, the compartment 10 is provided, for example, with shields 14 that extend in a predetermined path T of the preforms 2, for example between successive preforms 2, when the preforms 2 pass through the compartment 10, so as to block radiation directed towards the opening 12. These shields are, for example, rotatably movable so as to form a turnstile through which the preforms 2 must pass before passing between the emission walls 6 and / or after passing between these walls 6. Such a compartment 10 is described, for example, in document WO 2011 / 110791, so that they are not described in detail here. A person skilled in the art may refer to this document for more details on the implementation and arrangement of such a compartment 10 in a thermal treatment unit 1 .

[0032] like Figure 1 As shown, the housing 4 of the heat treatment unit 1 is also enclosed in a shield 16, which is arranged to prevent the radiation emitted in the housing 4 from leaving the housing 4. Therefore, the shield 16 is arranged to isolate the housing 4 from the place where the heat treatment unit 1 is placed as much as possible, so that operators can pass around the heat treatment unit 1 without risk of exposure to the radiation emitted in the housing 4. Therefore, the shield 16 closes the housing 4 along a predetermined path T at least on both sides of the housing 4 in the transverse direction and at least above the housing 4 in the vertical direction Z. To this end, the shield 16 extends along the walls 6 on the outside of the walls 6, covering the space extending between the walls 6 and the walls 6 above the housing 4. On the lower side of the housing 4, the shield 16 comprises, for example, an opening in the form of a slit to allow the passage of a system 8 for moving and clamping preforms 2 between the inside and the outside of the housing 4. The shield 16 also defines an opening 12 for the preforms 2 to enter and / or leave the housing 4, that is, the opening 12 is made in the shield. When one or more compartments 10 are provided, the shield 16 also surrounds the one or more compartments, such as Figure 1 shown.

[0033] According to one embodiment, the shield 16 comprises at least one removable wall 18 forming part of the shield 16. By removable wall 18 is meant that the removable wall 18 can be reversibly separated from the shield 16 and the rest of the housing 4, for example in order to release access to the housing 4 and elements extending therein for maintenance operations or other operations. To this end, the removable wall 18 is mounted on the housing of the shield 16, for example by reversible fastening elements, which allow fastening the removable wall 18 to the housing and dismantling the removable wall 18 in order to separate it from the housing. The removable wall 18 extends between an inner surface 20, which faces the interior of the housing 4 when the removable wall 18 is mounted on the housing, and an outer surface 22, which faces opposite the inner surface 20 and faces the exterior of the housing 4. The removable wall 18 is arranged to prevent radiation emitted by the emitting element from passing from the inner surface 20 to the outer surface 22 of the removable wall 18. To this end, the removable wall 18 can be made of a material that prevents this passage, for example absorbs radiation to prevent this passage, or the inner surface 20 can be coated with such a material. As a variant, the material can be a material that reflects radiation. The removable wall 18, for example, complies with a laser passive protector as defined in the CEI 60825-4 (corresponding to the English IEC 60825-4) standard.

[0034] The removable wall 18 is arranged in a predetermined area of ​​the housing 4. The predetermined area corresponds in particular to an area in which radiation emitted by the emitting element in the absence of the removable wall 18 can leave the housing 4, while the radiation is blocked by the housing when the removable wall 18 is mounted on the rest of the shield 16. Thus, the predetermined area extends, for example, at the edge of the opening 12 of the housing, or along a portion of the emitting wall 6 or facing the emitting wall 6. In other words, the removable wall 18, for example, defines at least one edge of the opening 12 of the housing 4 and / or extends in a transverse direction towards one or more emitting elements.

[0035] According to a particularly advantageous embodiment, Figure 1 As shown, the shield 16 is formed by an assembly of multiple removable walls 18, that is, the shield 16 is completely removable. Each removable wall 18 is arranged in a predetermined area of ​​the housing 4, and their assembly allows the housing 4 to be completely closed outside the area where the housing 4 must be opened, as described above. It can therefore be understood that when all removable walls 18 are installed on the housing 4, radiation leakage may only occur at the openings provided in the housing 4, and the housing 4 may be provided with elements for reducing the risk of leakage at the openings, such as the compartment 10 described above. It is also understood that when the thermal treatment unit is in operation, the absence of a removable wall 18 in the corresponding predetermined area may lead to radiation leakage at the predetermined area, thereby causing risks to operators active opposite to the predetermined area.

[0036] The thermal treatment unit according to the invention comprises a safety system comprising at least one image acquisition device 24 arranged outside the housing 4, facing at least a portion of the shield 16, arranged to acquire at least one image of at least this portion of the shield 16. The safety system further comprises processing means 26 for processing the images acquired by the image acquisition means 24, the processing means 26 being arranged to determine whether there is a radiation leakage outside the housing 4 based on the acquired images. Thus, the safety system can check that the radiation emitted by the emission wall 6 during the operation of the thermal treatment unit does not escape from the housing 4, i.e. it is not stopped by the shield 16. According to one embodiment, the safety system further comprises an alarm device arranged to warn an operator and / or stop or prevent the operation of the thermal treatment unit if the processing means 26 detects the presence of a radiation leakage. Thus it is ensured that when a radiation leakage outside the housing 4 is detected, the thermal treatment unit is not operated, or at least an operator active around the thermal treatment unit is informed of the presence of a leakage and can take appropriate measures.

[0037] The image acquisition device 24 is arranged outside the housing 4 to acquire images of the outside of the shield 16, such as Figure 1 shown.

[0038] Image acquisition device 24 comprises, for example, at least one camera that captures images in at least the near infrared range, the camera being oriented such that at least a portion of shield 16 extends within the range of the camera. By near infrared is meant wavelengths approximately between 0.7 μm and 1.6 μm.

[0039] More specifically, the image acquisition device 24 is positioned so that at least one opening 12 is within the range of the acquired image. In fact, the opening 12 for the preform 2 to enter and / or leave the housing 4 is the location where radiation leakage is most likely to occur, even when a shielding member 14 as described above is provided. When the same opening 12 allows the entry and exit of the preform, or when the entry opening and the exit opening are adjacent, a single image acquisition device 24 can be provided to detect the presence of a leak at the opening 12. When the entry opening and the exit opening are separated, it is preferred to provide an image acquisition device 24 for each opening in order to monitor the presence of a leak at each opening 12. The image acquisition device 24 or additional image acquisition devices 24 can also be positioned to detect the possible presence of leaks at other locations of the shield 16, in particular at the removable wall 18 extending along the emission wall 6, such as Figure 1 This embodiment is advantageous, in particular, for detecting whether the removable wall 18 is damaged and allowing radiation to pass from the inner surface 20 to the outer surface 22 .

[0040] According to one embodiment, the image acquisition device 24 is also arranged to acquire an image in the visible light range of at least one predetermined area in which the removable wall 18 must be located. The processing device 26 can then also be used to determine whether a removable wall 18 is present in the acquired image of the predetermined area. Thus, the safety system allows, for example, to check that the removable wall 18 is indeed in place before any start-up of the thermal treatment unit 1. According to one embodiment, the alarm device is also arranged to issue a warning to the operator and / or stop or prevent the operation of the thermal treatment unit if the processing device detects that a removable wall 18 is not present in the predetermined area. In this way, it is ensured that the thermal treatment unit is only operated when the removable wall 18 is indeed in place.

[0041] When the thermal treatment unit 1 comprises a plurality of removable walls 18, in particular a plurality of removable walls 18 adjacent to one another, the image acquisition device 24 is arranged to acquire one or more images of the plurality of removable walls 18, for example by providing a camera frame to include a plurality of predetermined areas for acquisition, so that the acquisition of a single image by the camera allows the detection of the presence or absence of radiation leakage in all these predetermined areas, or even the presence or absence of all these removable walls 18. As a variant or as a supplement, the image acquisition device 24 is movable relative to the housing 4 and / or comprises a movable part, such as a mirror, so that the image acquisition device can acquire some images of the plurality of predetermined areas in order to detect the presence or absence of leakage in these areas, or even the presence or absence of removable walls 18 in these predetermined areas. Thus, the image acquisition device 24 is movable, for example, in rotation, in order to scan the plurality of predetermined areas and acquire at least one image for each of these predetermined areas. The processing device 26 is then configured to determine in each image whether there is a radiation leakage in each predetermined area.

[0042] The image processing device 26 is configured to determine whether radiation is present outside the housing 4 by analyzing the image captured by the image capture device. For example, this determination is based on an analysis of the image chromaticity, where image areas where radiation is present appear, for example, lighter than areas where no radiation is present. According to one embodiment, the processing device 26 can be configured to perform processing of the captured image in order to highlight possible radiation and / or to determine the intensity of the radiation. Thus, for example, when the detected radiation level exceeds the maximum permissible exposure value (EMP: corresponding to English MPE) as defined in the CEI 60825-1 (corresponding to English IEC 60825-1) standard and / or exceeds the protective exposure limit (LEP: corresponding to English PEL) as defined in the CEI 60825-4 (corresponding to English IEC 60825-4) standard, the intervention of the alarm device can be triggered.

[0043] The image processing device 26 may also determine areas where radiation leakage has occurred so that the operator can take necessary measures to eliminate the radiation leakage. The validity of these measurements may be determined by acquiring new images of the area of ​​interest and using the processing device 26 to determine if there is still leakage in the area.

[0044] When the security system is also arranged to detect the presence or absence of one or more removable walls 18 in one or more predetermined areas, the image processing means 26 is, for example, configured to compare the acquired image with an image in which all removable walls 18 corresponding to the predetermined areas whose images were acquired by the image acquisition means 24 are present. Thus, the image processing means allow determining in a simple manner whether a removable wall 18 is not present in the image, as soon as there is a difference between the processed image and the image in which all removable walls 18 are present.

[0045] As a variant or as a supplement, each removable wall 18 may include at least one identification element 28, the image of which is captured by the image acquisition device 24 during the check for the presence of the removable wall 18. The image processing device 26 is then configured to detect the presence of the identification element 28 in the image captured by the image acquisition device 24 in order to determine whether the removable wall 18 is present in the predetermined area. In addition to checking the presence or absence of the removable wall 18, the detection of the identification element 28 may also allow determining whether the detected removable wall 18 is indeed the removable wall that must be placed in the predetermined area whose image has been captured. In fact, the identification element 28 allows each removable wall 18 to be distinguished from the other removable walls and allows a removable wall 18 to be associated with a predetermined area in an individual manner. In addition to the image comparison described above, the detection of the identification element 28 can also be performed, as an alternative to the comparison, so that the positioning of the identification element in the image can be realized in a simpler way than the image comparison, in particular from a software point of view. The identification element 28 is formed, for example, by a QR code, such as Figure 1 As shown, or formed by any other suitable identification element such as a bar code or others. The identification element 28 is applied to the outer surface 22 of the removable wall 18.

[0046] In the figure, each image acquisition device 24 is associated with an image processing device 26. However, it should be understood that the same image processing device 26 can be used for a plurality of image acquisition devices 24. As a variant, the image acquisition device 24 and the image processing device 26 can be combined to form part of the same system, for example in the same housing.

[0047] As previously described, for example, the detection of the presence of a leak, even of the removable wall 18 , is triggered before any putting into production the heat treatment unit 1 , which is prevented as soon as at least one radiation leak outside the enclosure 4 is detected.

Claims

1. A heat treatment unit (1) for heat treating a preform (2) of a container manufacturing device, the heat treatment unit comprising a housing (4), the preform (2) traveling along a predetermined path (T) in the housing, the heat treatment unit further comprising at least one emission wall (6), the emission wall comprising at least one emission element for emitting monochromatic or pseudo-monochromatic electromagnetic radiation, the emission element being arranged to emit radiation to the preform (2) passing through the housing (4), the housing (4) being at least partially enclosed by a shield (16), the shield being arranged to prevent radiation from passing through the shield (16) to the outside of the housing (4), the heat treatment unit being characterized in that the heat treatment unit further comprises at least one emission wall (6) A safety system is disclosed, the safety system comprising at least one image acquisition device (24) and at least one processing device (26), wherein the image acquisition device is arranged outside the shield (16) and the processing device is used to process images acquired by the image acquisition device (24), the image acquisition device (24) acquires images within at least a near-infrared range, and the images acquired by the image acquisition device (24) are capable of displaying radiation emitted outside the shield (16), and the processing device (26) is configured to identify the presence of radiation leakage outside the housing (4) if at least one image acquired by the image acquisition device (24) displays radiation emitted outside the shield (16).

2. The heat treatment unit according to claim 1, characterized in that The shield (16) comprises at least one opening (12) for the preform (2) to enter and / or leave the housing (4), and at least one image captured by the image capture device (24) shows at least the opening (12).

3. The heat treatment unit according to claim 1 or 2, characterized in that: The safety system further comprises an alarm device arranged to warn an operator and / or to stop or prevent operation of the thermal treatment unit if the processing device (26) identifies the presence of radiation leakage outside the housing (4).

4. The heat treatment unit according to claim 3, characterized in that When the radiation level detected by the processing device (26) exceeds the maximum permissible exposure value (EMP) as defined in the CEI 60825-1 standard and / or the protective exposure limit (LEP) as defined in the CEI 60825-4 standard, the alarm device is triggered.

5. The heat treatment unit according to any one of claims 1 to 4, characterized in that: The shield (16) comprises at least one removable wall (18) arranged in a predetermined area of ​​the housing (4), the image acquisition device (24) is further arranged to acquire images in the visible light range, the image acquisition device (24) is arranged to acquire at least one image of the predetermined area, and the processing device (26) is configured to detect whether the removable wall (18) is present in the acquired image.

6. The heat treatment unit according to claim 5, characterized in that The removable wall (18) comprises at least one identification element (28), the image acquisition device (24) is arranged to acquire at least one image of the identification element (28), and the processing device (26) is configured to detect whether the identification element (28) is present in the acquired image.

7. A heat treatment unit according to claim 5 or 6 as appended to claim 2, characterised in that A removable wall (18) defines at least a portion of the opening (12).

8. The heat treatment unit according to any one of claims 1 to 7, characterized in that The image acquisition device (24) includes at least one camera that captures images in at least the near infrared range, the camera being oriented so that at least a portion of the shield (16) extends within the range of the camera.

9. The heat treatment unit according to any one of claims 1 to 8, characterized in that: The safety system comprises a plurality of image acquisition devices (24), each of which is arranged to acquire at least one image of a different area of ​​the shield (16), and the processing device (26) is configured to identify the presence of radiation leakage outside the housing (4) if at least one image acquired by the image acquisition device (24) shows radiation emitted outside the shield (16).

10. The heat treatment unit according to any one of claims 1 to 9, characterized in that The image acquisition device (24) is movable relative to the housing and / or includes at least one movable element, so that the image acquisition device (24) acquires images of multiple areas of the shield (16) by moving relative to the housing (4) to detect whether there is radiation leakage in the multiple areas.

Images