Device for optical detection of position or shape defects of hollow bodies in a conveyor belt of a heat conditioning unit

Abstract

Disclosed is a device (23) for detecting shape or position defects of hollow bodies (2) on a straight path (TR) defined by a conveyor belt (1) for conveying the hollow bodies (2), each hollow body having a main axis (X), the device (23) comprising: an optical assembly (24) with an integrated transmitter, the transmitter generating a light beam (25) along a light path, at least one section of which is oriented parallel to the straight path (TR) and is laterally displaced relative to a mid-plane (M) swept by the main axis (X) of the hollow body (2) by a distance (D) greater than half the width (R) of the hollow body (2) and less than twice the width (R) of the hollow body (2); a target (26) positioned away from the optical assembly (24), the target (26) being provided with a reflector (27) or a photosensor intercepting the light path of the light beam (25), the photosensor or the reflector (27) being respectively capable of detecting the light beam or reflecting the light beam to an optical receiver integrated at the optical assembly (24).

Description

Technical Field

[0001] The invention relates to the automatic control of hollow bodies transported by means of a conveyor belt.

[0002] More precisely, the invention relates to a detection device for detecting positioning defects of hollow bodies which pass through a straight path defined by a conveyor belt of hollow bodies. Background Art

[0003] These hollow bodies are for example preforms of containers of plastic material (eg PET).The preforms typically comprise a cylindrical body ending in a hemispherical bottom, a neck having the final shape, and a flange separating the neck from the body.

[0004] In facilities for making containers from preforms, the injected green preforms are generally stored in bulk in packing boxes. The preforms are first taken out of the packing boxes and oriented in rows for introduction into a heat conditioning unit (more simply called an oven) equipped with infrared emitters (typically in the form of tubular halogen lamps, or laser diodes), where the bodies of the preforms are brought to a temperature above their glass transition temperature (about 80° C. for PET). The hot preforms are then transported to a molding device equipped with a plurality of molds, where the preforms are formed into containers in the mold cavity by blowing or stretch blowing.

[0005] In the furnace, the preforms are conveyed linearly by a conveyor chain comprising a plurality of links, each provided with a support called a "turntable" provided with a chuck mounted for translation between an inactive position and an active position in which it engages the neck of the preform.

[0006] During the translation of the conveyor chain, each turntable is driven to rotate through a rack meshing with a gear connected to the chuck. In this way, the preform embedded in the chuck head is driven to translate and rotate simultaneously in the furnace so as to be fully exposed to the radiation of the infrared emitter.

[0007] The structure of such a conveyor chain is well described in European patent EP 0 935 572 (Sidel). The conveyor chain is generally mounted between two wheels, a driving wheel that drives the chain, and a following wheel. One of the wheels (e.g. the driving wheel) is located upstream of the furnace, and the other wheel (e.g. the following wheel) is located downstream of the furnace.

[0008] In certain configurations, the conveyor chain forms a plurality of parallel paths along which the hollow bodies are arranged in rows, see for example European Patent EP 2 623 439 (Sidel).

[0009] The preforms from the packaging boxes are loaded on the upper wheel through rails or gears, each preform is perpendicular to the turntable, and the chuck of the turntable is in an inactive position. During the rotation of the upper wheel, the chuck moves to its active position, the head is embedded in the neck of the preform (an operation called socketing), so that the preform is connected to the chuck in rotation. From then on, the gear meshes with the rack at the furnace entrance, and the preform is driven to rotate.

[0010] The production rate of such a facility is typically about 50,000 containers per hour, which corresponds to the travel rate of the preforms in the furnace, with the speed of the preforms on the wheels being about 1 m / s.

[0011] At this speed, positioning problems may arise; in fact, it may happen that the preform is not correctly centered relative to the chuck and, therefore, the chuck does not fit correctly onto the neck of the preform.

[0012] The absence of a preform in the production line does not cause any particular problems, but for safety reasons it is necessary to detect badly positioned preforms so that they can be ejected from the furnace. For example, when eccentrically or engaged in an angularly offset manner relative to the axis of the chuck, the preform is badly positioned on the chuck and the preform may break a tubular halogen lamp or a laser diode located nearby as it moves.

[0013] It is known in particular from European patent EP1781460 (Sidel) to eject a poorly positioned preform by means of a mechanical device which detects a chuck position between an active position and an inactive position of the chuck corresponding to a poor engagement of the chuck head on the preform neck.

[0014] This device is satisfactory when the preform is poorly positioned at the wheel (which is the majority of cases), but it cannot detect:

[0015] - preforms that were correctly positioned at the upstream wheel, but subsequently became poorly positioned, for example when overturning occurred between the upstream wheel and the heating zone (the path of which is linear), generally due to the centrifugal forces that accompany overturning;

[0016] - Preforms that, while correctly positioned, have shape defects (e.g. due to squeezing). Summary of the invention

[0017] The present invention aims to propose a solution which makes it possible to more reliably detect defects in the shape or positioning of hollow bodies (typically preforms) in a conveyor belt.

[0018] To this end, a device is first proposed for detecting shape or position defects of hollow bodies passing through a straight path defined by a conveyor belt of hollow bodies, each hollow body having a main axis, the device comprising:

[0019] - an optical assembly incorporating an emitter generating a light beam along a light path, at least a section of which is oriented parallel to said path and laterally displaced by a distance greater than half the width of the hollow body relative to a median plane swept by the main axis of the hollow body in a standard position;

[0020] - a target positioned remote from the optical assembly, the target being provided with a reflector or a photosensor intercepting the optical path of the light beam, the photosensor or the reflector being respectively able to detect the impact of the light beam on the photosensor or to reflect the light beam towards an optical receiver integrated at the optical assembly.

[0021] When the hollow body has a shape or positioning defect, the hollow body is inserted in the optical path between the optical component and the target and struck by the laser beam, thus allowing the shape or positioning defect to be detected.

[0022] Various additional features may be considered individually or in combination. Thus, for example:

[0023] -The optical components are mounted on adjustable supports;

[0024] - the support comprises a bracket, the bracket comprises a column and a crossbeam fixed to the column, and the optical component is mounted on the crossbeam;

[0025] -The column is installed in a vertical direction relative to the fixed plate;

[0026] - The support includes rollers for adjusting the position of the column relative to the board in the vertical direction;

[0027] - the support includes a brake lever, the tightening of which ensures the position of the locking column relative to the plate;

[0028] -The crossbeam is installed in a lateral translation relative to the column;

[0029] -The crossbeam is installed in a longitudinal translation relative to the column;

[0030] - the support comprises a slider mounted for translation relative to the column in the transverse direction, and the crossbeam is mounted for translation relative to the slider in the longitudinal direction;

[0031] - the support includes rollers for adjusting the position of the crossbeam relative to the uprights in the transverse direction;

[0032] - the support comprises a brake lever, the tightening of which ensures the locking of the position of the crossbar in the transverse direction;

[0033] - the support comprises at least one position indicator of the optical component;

[0034] - the target comprises a reflector covered with a prism;

[0035] - The target is mounted on the foot in an adjustably manner.

[0036] According to a particular embodiment, in order to detect, on two rectilinear paths, defects in the shape or positioning of a hollow body passing through at least one of these paths, the device comprises:

[0037] - a first optical assembly integrating an emitter, the emitter generating a light beam along a first light path, at least a section of the first light path being oriented parallel to the first path;

[0038] - a first target positioned remote from the first optical assembly, the first target being provided with a reflector or a light-sensitive sensor intercepting the first light path;

[0039] - a second optical assembly incorporating an emitter generating a light beam along a second light path, at least a section of the second light path being oriented parallel to the second path;

[0040] - a second target positioned remote from the first optical assembly, the first target being provided with a reflector or a light-sensitive sensor intercepting the second light path.

[0041] Other additional features may also be considered. Thus, for example:

[0042] - the optical component is positioned in the extension of said path;

[0043] - Relative positioning of the target and the optical assembly;

[0044] - the path is defined between an entry point and an exit point, the optical component being positioned at the exit point or at the entry point;

[0045] - the target is positioned relative to the optical assembly at the entry point or respectively the exit point;

[0046] - the optical component is laterally offset from said path, and said device comprises an optical angle reflector (such as a prism or a mirror) positioned to orient said segment of the optical path parallel to said path;

[0047] - The optical component integrates an optical bandpass filter having a passband centered on a predetermined wavelength.

[0048] - The transmitter generates a laser beam.

[0049] In a second aspect, a conveyor belt of a thermal conditioning unit for conveying hollow bodies (2) is proposed, wherein the conveyor belt is equipped with a detection device (23) as described above.

[0050] In a third aspect, a detection device for detecting shape or positioning defects of a hollow body in a heat conditioning unit for a hollow body is provided, the heat conditioning unit comprising a conveyor belt of hollow bodies defining at least one straight path, the hollow bodies passing through the straight path and each hollow body having a main axis, the device comprising:

[0051] - an optical assembly incorporating an emitter generating a light beam along a light path, at least a section of which is oriented parallel to the rectilinear path and is laterally displaced relative to a median plane swept by the main axis of the hollow body in a standard position by a distance greater than half the width of the hollow body and less than twice the width of the hollow body;

[0052] - a target positioned remote from the optical assembly, the target being provided with a reflector or a photosensor intercepting the optical path of the light beam, the photosensor or the reflector being respectively able to detect the impact of the light beam on the photosensor or to reflect the light beam towards an optical receiver integrated at the optical assembly.

[0053] When the hollow body has a shape or positioning defect, the hollow body is inserted in the optical path between the optical component and the target and struck by the laser beam, thus allowing the shape or positioning defect to be detected.

[0054] Various additional features may be considered individually or in combination. Thus, for example:

[0055] -The optical components are mounted on adjustable supports;

[0056] - the support comprises a bracket, the bracket comprises a column and a crossbeam fixed to the column, and the optical component is mounted on the crossbeam;

[0057] -The column is installed in a vertical direction relative to the fixed plate;

[0058] - The support includes rollers for adjusting the position of the column relative to the board in the vertical direction;

[0059] - the support includes a brake lever, the tightening of which ensures the position of the locking column relative to the plate;

[0060] -The crossbeam is installed in a lateral translation relative to the column;

[0061] -The crossbeam is installed in a longitudinal translation relative to the column;

[0062] - the support comprises a slider mounted for translation relative to the column in the transverse direction, and the crossbeam is mounted for translation relative to the slider in the longitudinal direction;

[0063] - the support includes rollers for adjusting the position of the crossbeam relative to the uprights in the transverse direction;

[0064] - the support comprises a brake lever, the tightening of which ensures the locking of the position of the crossbar in the transverse direction;

[0065] - the support comprises at least one position indicator of the optical component;

[0066] - the target comprises a reflector covered with a prism;

[0067] - The target is mounted on the foot in an adjustably manner.

[0068] According to a particular embodiment, in order to detect, on two rectilinear paths, defects in the shape or positioning of a hollow body passing through at least one of these paths, the device comprises:

[0069] - a first optical assembly integrating an emitter, the emitter generating a light beam along a first light path, at least a section of the first light path being oriented parallel to the first path;

[0070] - a first target positioned remote from the first optical assembly, the first target being provided with a reflector or a light-sensitive sensor intercepting the first light path;

[0071] - a second optical assembly incorporating an emitter generating a light beam along a second light path, at least a section of the second light path being oriented parallel to the second path;

[0072] - a second target positioned remote from the first optical assembly, the first target being provided with a reflector or a light-sensitive sensor intercepting the second light path.

[0073] Other additional features may also be considered, so for example:

[0074] - the optical component is positioned in the extension of said path;

[0075] - Relative positioning of the target and the optical assembly;

[0076] - the path is defined between an entry point and an exit point, the optical component being positioned at the exit point or at the entry point;

[0077] - the target is positioned relative to the optical assembly at the entry point or respectively the exit point;

[0078] - the optical component is laterally offset from said path, and said device comprises an optical angle reflector (such as a prism or a mirror) positioned to orient said segment of the optical path parallel to said path;

[0079] - The optical component integrates an optical bandpass filter having a passband centered on a predetermined wavelength.

[0080] - The transmitter generates a laser beam.

[0081] In a fourth aspect, a heat conditioning unit for hollow bodies is provided, each hollow body having a main axis, the heat conditioning unit comprising a conveyor belt for hollow bodies, the conveyor belt defining at least one straight path and a middle plane swept by the main axis of the hollow bodies along the straight path, the heat conditioning unit further comprising at least one lateral radiating wall disposed laterally away from the middle plane, and a detection device for detecting a shape or positioning defect in one of the hollow bodies conveyed by the conveyor belt along the straight path;

[0082] The detection device comprises an optical assembly integrating an emitter generating a light beam along a light path, at least one section of which is oriented parallel to the rectilinear path and laterally displaced relative to the median plane, the light beam being strictly located in the space extending between the lateral radiating wall and the wall of the preform.

[0083] Various additional features may be considered individually or in combination. Thus, for example:

[0084] A target positioned remote from the optical assembly is provided with a reflector or a photosensor intercepting the optical path of the light beam, the photosensor or the reflector being able to detect the impact of the light beam on the photosensor or to reflect the light beam towards an optical receiver integrated at the optical assembly, respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Other objects and advantages of the present invention will become clear from the description of embodiments with reference to the following drawings:

[0086] Figure 1 : is a perspective view showing a thermal conditioning unit of a preform equipped with a detection device according to the invention, with a larger scale detail focused on the area where the optical assembly is located in the upper frame of the figure and a larger scale detail focused on the area where the target is located in the lower frame;

[0087] Figure 2 is a perspective view of the detection device in operation when the hollow body conforms to the normal shape and positioning;

[0088] Figure 3 yes Figure 2 A detailed perspective view of the installation from another angle;

[0089] Figure 4 Yes Figure 2 A larger scale perspective view of details of the optical components of the detection device is shown;

[0090] Figure 5 yes Figure 4 A detailed perspective view of the optical components along another viewing angle;

[0091] Figure 6 is with Figure 2 A similar diagram shows the detection device in operation when the hollow body has shape or positioning defects;

[0092] Figure 7 It is a schematic diagram made in the axis of the optical assembly and represents the operation of the optical assembly. DETAILED DESCRIPTION

[0093] Figure 11 shows a conveyor belt 1 for ensuring the transport of hollow bodies 2. In the example shown, the hollow bodies 2 are preforms from which containers are to be formed (by blowing or stretch-blowing). Of course, the hollow bodies 2 can be different: they can be molds or even containers. However, it is assumed below that the hollow bodies 2 are preforms, which are preferably formed from a plastic material (generally PET).

[0094] Each prefab 2 (see Figure 2 ) comprises a cylindrical body 3 extending along a main axis X, an open neck 4 extending from a first end of the body 3, and a hemispherical bottom 5 extending to the other end of the body 3. In the example shown, the preform 2 comprises a flange 6 separating the body 3 and the neck 4. R represents the half width measured between the main axis X and the periphery of the body 3. As in the example shown, the body 3 is a cylinder of revolution, and the half width R represents the radius of the body 3.

[0095] Here, a conveyor belt 1 is used to transport the preforms 2 in an arranged manner to a thermal conditioning unit 7, also called an oven, which comprises one or more radiation walls 8 (two in the example shown), each wall being equipped with one or more rows of infrared radiation sources, here in the form of tubular lamps (e.g. halogen lamps).

[0096] In the oven 7, the preform bodies 2 are exposed to radiation from the walls 8 in order to be heated to a temperature above their glass transition temperature (about 80° C. in the case of PET) in order to subsequently form containers in a molding unit (not shown) equipped with a mold having a plurality of cavities with containers of a given model.

[0097] Firstly, the conveyor belt 1 comprises a fixed frame 9. In the example shown, the frame 9 comprises a pair of legs 10 and one or more beams 11 connecting the legs.

[0098] Secondly, the conveyor belt 1 comprises a transport chain 12 defining a predetermined path along which the preforms 2 move. This path extends along a closed loop. In the example shown, this path comprises two straight paths TR connected by a curved (especially circular) path TC. In a variant not shown, this path comprises a single straight path TR. In another variant not shown, this path comprises two adjacent straight paths TR close together, on which the preforms 2 move in two parallel rows, as in the configuration described in patent EP 2 623 439 (Sidel).

[0099] To return to the example shown, the conveyor chain 12, only partially shown in the figure, comprises two straight sides 13, each defining a straight path TR, and two arcuate sides 14, each defining a curved path TC. In its curved sides 14, the conveyor chain 12 is transported on at least one of its wheels 15, which is a motorized wheel. Each straight side TR defines a longitudinal direction of movement and extends between an entry point E and an exit point S.

[0100] The conveyor chain 12 comprises chain links 16 which are articulated to one another via hooks 17 .

[0101] Each link 16 carries at least one sheath 18 and a support 19 for the preform 2. Due to the rotating nature of the support 19, the support 19 is hereinafter referred to as a turntable, and the turntable 19 is provided with: - a chuck 20 pivotally mounted in sliding relation to the sheath 18 and having one end forming a nose that can be embedded in the neck 4 of the preform;

[0102] - A gear 21 rotatably connected to the chuck 20, the gear 20 meshes with the fixed rack (because it is blocked by the conveyor chain 12, Figure 1 (not visible in the image).

[0103] Each link 16 is additionally provided with an ejector 22 connected to the sheath 18 .

[0104] When the preform 2 is mounted in the turntable 19 , the preform 2 is rotated by the turntable 19 so that the entire surface of the preform body 3 is exposed to the radiation of the (or each) wall 8 .

[0105] Each turntable 19 is installed in translation relative to the sheath 18 between an extended position and a retracted position. In the extended position, the chuck 20 protrudes from the ejector 22 so as to be engaged in the neck 4 of the preform 2 (an operation called sleeve engagement). In the retracted position, the chuck 20 is accommodated in the ejector 20 so as to be removed from the neck 4 abutting against the ejector 22 (an operation called unsleeving).

[0106] The sleeve and release are on one of the wheels 15 ( Figure 1 During these operations, the neck 4 of the preform 2 is facing upwards. After the nesting, the preform 2 is turned over so that the neck 4 is facing downwards before being introduced into the oven 7. At the exit of the oven 7 (and therefore at the end of the thermal conditioning), the preform 2 is turned over again so as to be withdrawn from the conveyor belt 1 and transferred to the molding unit.

[0107] In the straight path TR of the route, the main axis X of the preform 2 in a perfectly positioned (ie vertical, without defects in shape or positioning) sweeps through a median plane M extending simultaneously vertically and longitudinally.

[0108] In the example shown, the entry point E and the exit point S are the end points of the straight path TR, at which the main axis X of the preform 2 leaves the middle plane M (or rejoins the middle plane M) when the preforms enter (or leave) the curved path TC, or when they are turned over.

[0109] While passing through the straight path TR, the body 3 of the preform 2 sweeps a volume VB ( Figure 7 The half-width of the volume measured transversely (ie perpendicular to the middle plane M) is equal to the half-width R of the preform.

[0110] However, prefab 2 may exist:

[0111] - Locating defects, usually when socketing is not implemented correctly, or

[0112] - Shape defects (such as Figure 6 as well as Figure 7 dotted lines), for example when the preform 2 is subjected to deformations resulting in particular from erroneous injection, collisions or even squeezing.

[0113] In this case a detection should be performed so that it can be ejected.

[0114] Therefore, the conveyor belt 1 is equipped, on one and / or the other of the rectilinear paths TR, with detection devices 23 configured to optically detect shape or positioning defects of the preforms 2 passing through this path(s) TR.

[0115] The detection device 23 firstly comprises an optical component 24 .

[0116] This optical assembly 24 integrates an emitter generating a light beam 25 (advantageously calibrated) along an optical path, at least a section (or a portion) of which is oriented parallel to the straight path TR, so that this section (and therefore, at least locally, the light beam 25) is laterally displaced relative to the median plane M by a distance D greater than half the width of the preform 2 (half the width of the volume VB swept by the preform 2 of its shape and positioning standard) and less than twice the width of the preform (usually corresponding to the position of the radiation wall). In other words, the light beam 25 can preferably be located between the preform wall and the radiation wall. In the case where the light beam 25 is located on the wall of the hollow body or on the radiation wall, any defect detection is impossible.

[0117] In other words, the distance of the beam to the mid-plane swept along the straight path by the preform axis (X) is preferably strictly greater than half the width of the hollow body and / or strictly within the space extending between the lateral radiating walls and the preform walls.

[0118] In a first embodiment, the light beam 25 is preferably a laser, i.e. a collimated intense light beam with a narrow optical passband. However, in a second embodiment, a light beam with a wider optical passband may be involved. In both embodiments, the optical assembly integrates an optical bandpass filter with a passband centered on a predetermined wavelength. Whichever embodiment is considered, the wavelength or, respectively, the passband is selected so that the wavelength of the radiation emitted by the preform 2 does not interfere with the light beam, in order to avoid any detection errors.

[0119] In the following, a first embodiment is considered, whereby it is assumed that the light beam 25 is a laser, without excluding other embodiments.

[0120] like Figure 1 As shown in the detailed block diagram of , a light path shift is achieved towards the outside of the path TR (ie on the side opposite to the curved path(s) TC) to avoid that the preforms 2 transported in a standard manner on the curved path(s) TC cut the light beam.

[0121] Second, the detection device 23 includes a target 26 located away from the optical assembly 24. The target 26 has:

[0122] - or (first case), a photosensor which intercepts the path of the light beam 25 and is able to detect the impact;

[0123] or (the second case shown), a reflector 27 which intercepts the optical path of the light beam 25 and can reflect it towards an optical receiver integrated into the optical assembly 24 .

[0124] In the first case, the detection device 23 may or may not be operational, that is:

[0125] - As long as the photosensitive sensor equipped with the target 26 is excited, which proves that the light beam 25 reaching the target is not blocked, the detection device generates a first characteristic signal of the standard operation of the conveyor belt 1, in which case all the preforms 2 are qualified;

[0126] If, on the other hand, the photosensor equipped with the target 26 is not excited, this proves that an obstacle has been inserted in the optical path between the target and the emitter, and the detection device generates a second characteristic signal of degraded operation, in which case at least one preform 2 has a shape or positioning defect.

[0127] This first case is effective for detecting shape and positioning defects of preform 2, but it does not allow positioning the preform so as to be able to eject it without stopping the conveyor. In order to allow (manual) removal of the preform 2 in question, the conveyor must be stopped as a result.

[0128] In the second case, the detection device 23 can perform distance measurement. The optical assembly 24 equipped with both the transmitter and the receiver is configured to measure the actual optical path length of the laser beam 25 by triangulation:

[0129] - as long as the measured optical path length is equal to a predetermined standard value (corresponding approximately to twice the distance separating the optical component 24 from the reflector 27), the optical component 24 generates a first characteristic signal of standard operation, in which case all preforms 2 are qualified;

[0130] - If, on the other hand, the measured optical path length is less than the standard value, this indicates that there is a preform 2 with a shape or positioning defect that cuts off the light beam 25, and the optical assembly 24 generates a second characteristic signal of degraded operation, in which case at least one preform 2 has a shape or positioning defect. Since the distance from the optical assembly 24 (along the optical path) to the preform 2 in question can be measured, the computer can accurately position the preform 2 and, taking into account the movement speed of this preform 2 (known), control the ejection of this preform 2 when it reaches the area of ​​the conveyor belt 1 where the ejection system is located.

[0131] The optical assembly 24 is, for example, the Dx50 model (with transmitter and receiver) sold by the company SICK. According to a preferred embodiment, the reflector 27 is covered with a prism, which improves the quality of the optical signal captured by the receiver equipped with the optical assembly 24. Thus, the reflector is, for example, the PL100 model sold by the company SICK.

[0132] In the configuration shown, in which the optical path is a straight line, the (each) optical assembly 24 is located in the extension of the straight path TR, on the side of the exit point S (or as a variant, on the side of the entry point E). In this same configuration, the (each) target 26 is located in the extension of the straight path TR, on the side of the entry point E (or, respectively, on the side of the exit point S when the optical assembly 24 is located on the side of the entry point E). In this configuration, the (each) target is positioned opposite the corresponding optical assembly 24.

[0133] As a variant, the (each) optical assembly 24 may be laterally offset from the path TR of the preform. In this case, the means 23 comprise optical angular reflectors (such as prisms or mirrors) positioned so as to orient the optical path section parallel to the path TR.

[0134] When the path of the preform 2 includes two straight paths TR, in order to detect shape or positioning defects of the preform 2 passing through at least one path on these two paths, the device 23 includes:

[0135] a first optical assembly 24 integrating an emitter generating a light beam 25 along a first light path, at least one section of which is oriented parallel to the first path TR;

[0136] - a first target 26 positioned away from the first optical assembly 24, the first target 26 being provided with a reflector 27 or a light-sensitive sensor intercepting the first light path;

[0137] - a second optical assembly 24 integrating an emitter generating a light beam 25 along a second light path, at least one section of which is oriented parallel to the second path TR;

[0138] A second target 26 positioned remote from the first optical assembly 24, the first target 26 being provided with a reflector 27 or a light-sensitive sensor intercepting the second light path.

[0139] Whatever the embodiment considered, the optical assembly 24 (or each optical assembly) is preferably mounted on the frame 9 of the conveyor belt 1. More precisely, and as shown in the figures, the optical assembly 24 is mounted on a support 28 connected to the leg 10.

[0140] Since the dimensions of the preform 2 (in particular the half width R and possibly the height) can vary from one range to another depending on the container model to be produced, it is preferably possible to adjust at least the position of the optical component 24 (and optionally the position of the target 26).

[0141] This is why, in the example shown, the optical assembly 24 is mounted on an adjustable support 29. Figure 4 As can be seen in FIG. 2 , the support 29 is further fixed on the support 28 .

[0142] According to one embodiment, the support 29 includes a bracket 30. The bracket 30 includes a column 31 and a beam 32. The beam 32 is fixed to the column 30. The optical assembly 24 is mounted on the beam 32.

[0143] The upright column 31 extends vertically, and the cross beam 32 extends longitudinally. The optical component 24 is mounted on one end of the cross beam 32 by screwing, for example.

[0144] Especially in Figure 4 In the example shown, the support 29 includes a plate 33, and the column 31 is connected to the support 28 via the plate 33. Here, the column 31 is along ( Figure 4 The plate 33 is installed in a vertical direction (indicated by arrow V). The plate is fixed; however, it can be fixed on the support 28 at different predetermined heights. Figure 2 As shown, the scale plate 34 can be inserted between the sticker plate 33 and the support 28.

[0145] The fixation of the plate 33 on the scale plate 34 (or on the support 28 through the scale plate 34) can be achieved by means of a nut 35 (e.g. a star nut), and an indicator 36 (here in the form of a line engraved on the side of the plate 33) indicates the fixed height of the plate by cooperating with the scale of the plate 34.

[0146] Especially if Figure 4As seen in FIG. 2 , the support 29 preferably includes a roller 37 for adjusting the position of the column 31 (and therefore the bracket 30) relative to the plate 33 in the vertical direction V. The electronic indicator 38 is provided with a screen that can be coupled to the roller 37 so as to display the vertical position of the optical assembly 24.

[0147] The support 29 preferably includes a brake rod 39, and the fastening of the brake rod 39 can ensure the locking position of the column 31 relative to the plate 33. Figure 4 As shown, the brake lever 39 is screwed into the abutment plate 33; the brake lever includes a lug which, in the tightening position, applies a local friction force to the column 31 so as to lock the position of the column.

[0148] Vertical movement of the plate 33 relative to the plate 34 (by loosening and then re-tightening the nut 35) allows a rough adjustment of the vertical position of the optical assembly 24. Then, manipulation of the roller 37 allows a fine adjustment of the vertical position of the optical assembly.

[0149] According to a preferred embodiment, the cross beam 32 can be arranged in a transverse direction (a direction perpendicular to the middle plane M). Figure 4 The vertical axis (indicated by arrow T) is installed in translation relative to the column 31.

[0150] To this end, Figure 4 In the example shown, the support includes a slider 40 which is installed to be translatable relative to the column 31 along the transverse direction T, and the crossbeam 32 is fixed on the slider 40.

[0151] like Figure 5 As seen in FIG. 1 , the support is preferably provided with a roller 41 for adjusting the position of the slider 40 (and therefore the crossbeam 32 ) relative to the column 31 along the transverse direction T. An electronic indicator 42 provided with a screen can be coupled to the roller 41 to display the transverse position of the optical assembly 24 .

[0152] The support 29 preferably comprises a brake lever 43 , the tightening of which ensures locking of the position of the slide 39 (and therefore of the crossbar 32 ) in the transverse direction T.

[0153] According to a preferred embodiment, the cross beam 32 also extends in the longitudinal direction ( Figure 4 The crossbeam 32 is mounted for translation relative to the slider 40 (indicated by arrow L). In the example shown, the crossbeam 32 is connected to a square 44, which has the freedom of longitudinal translation on the slider 40. One or more rollers 45 can adjust the longitudinal position of the square 44 (and therefore the crossbeam 32) relative to the slider 40 (and therefore relative to the column 31, the plate 33 and the support 28).

[0154] The target 26 is preferably selected to be of sufficient size so as to always be hit by the laser beam 25 (except in the case of a poor positioning or deformation of the preform 2 ); however, the target is preferably adjustable to ensure that it is well positioned relative to the optical assembly 24 .

[0155] Thus, in the example shown, the target 26 is mounted in an adjustable manner on a foot 46 connected to the frame 9 (and more precisely, in the example shown, fixed to the beam 11 ).

[0156] As in Figure 2 As can be seen in FIG. 4 , the foot 46 is preferably curved so as not to hinder the turning over of the preform 2 (by the rotation of the link 16 ).

[0157] The detection device 23 just described has the following advantages:

[0158] Firstly, it makes it possible to detect a preform 2 having a positioning defect in the straight path TR (even if this preform 2 does not have such a defect at the wheel 15 in the curved path TC).

[0159] Secondly, it is possible to detect preforms 2 that have shape defects even under the assumption that the preforms do not have positioning defects.

[0160] Third, it can achieve this detection without contact.

[0161] The reliability of the detection device 23 is thus increased, in particular with respect to known mechanical detection devices.

Claims

1. A device (23) for detecting shape and position defects of hollow bodies (2), said device (23) being used in a unit (7) for thermal conditioning of hollow bodies, said unit (7) also being called a furnace, said unit (7) comprising one or more radiating walls (8) and a conveyor (1) for the hollow bodies (2) defining at least one straight path (TR) through which the hollow bodies pass between an entry point E and an exit point S of said unit (7) and each hollow body having a main axis (X), said device (23) comprising: - an optical assembly (24) incorporating an emitter, said emitter generating a light beam (25) between the wall of the hollow body (2) and said radiation wall (8) along a light path, at least a section of said light path being oriented parallel to said straight path (TR) and laterally displaced by a distance (D) greater than half the width (R) of the hollow body (2) and less than twice the width of the hollow body (2) relative to a median plane (M) spanned by the main axis (X) of the hollow body (2) in a standard position; - a target (26) positioned remote from the optical assembly (24), the target (26) being provided with a reflector (27) or a photosensor intercepting the optical path of the light beam (25), the photosensor or the reflector (27) being respectively capable of detecting the impact of the light beam on the photosensor or reflecting the light beam towards an optical receiver integrated at the optical assembly (24), so that when the hollow body (2) has a shape or positioning defect, the hollow body is inserted in the optical path between the optical assembly (24) and the target (26) and is impacted by the light beam (25) between the wall of the hollow body (2) and the radiation wall (8), thus enabling the shape or positioning defect to be detected.

2. The device (23) according to claim 1, characterized in that The optical assembly (24) is mounted on an adjustable support (29).

3. The device (23) according to claim 2, characterized in that The support (29) comprises a bracket (30), the bracket (30) comprises a column (31) and a crossbeam (32) fixed on the column (31), and the optical component (24) is mounted on the crossbeam (32).

4. The device (23) according to claim 3, characterized in that The upright post (31) is installed to be translated relative to the fixed plate (33) along the vertical direction (V).

5. The device (23) according to claim 4, characterized in that The support (29) comprises a first roller (37) for adjusting the position of the column (31) relative to the mounting plate (33) along a vertical direction (V).

6. The device (23) according to claim 5, characterized in that The support (29) comprises a first brake rod (39), the tightening of which can ensure that the position of the column (31) relative to the plate (33) is locked in the vertical direction (V).

7. The device (23) according to any one of claims 3 to 6, characterized in that The crossbeam (32) is installed in a translational manner relative to the column (31) along the transverse direction (T).

8. The device (23) according to claim 7, characterized in that The crossbeam (32) is installed in a translational manner relative to the column (31) along the longitudinal direction (L).

9. The device (23) according to claim 7, characterized in that The support (29) comprises a slider (40) which is installed to translate relative to the column (31) in a transverse direction (T), and the crossbeam (32) is installed to translate relative to the slider (40) in a longitudinal direction (L).

10. The device (23) according to claim 7, characterized in that The support (29) comprises a second roller (41) for adjusting the position of the cross beam (32) relative to the column (31) in the transverse direction (T); the support (29) comprises a second brake rod (43), and the tightening of the second brake rod can ensure the locking of the position of the cross beam (32) in the transverse direction (T).

11. The device (23) according to claim 2, characterized in that The support (29) comprises at least one position indicator of the optical component (24).

12. The device (23) according to claim 1, characterized in that The optical component (24) is positioned in an extension of the path (TR), and the target (26) is positioned opposite to the optical component (24).

13. The device (23) according to claim 12, characterized in that The path (TR) is defined between an entry point (E) and an exit point (S), the optical component (24) being positioned at the exit point (S) or the entry point (E); the target (26) being positioned opposite the optical component (24) at the entry point (E) or the exit point (S), respectively.

14. The device (23) according to claim 1, characterized in that The target (26) comprises a reflector (27) covered with a prism; and / or The target (26) is adjustably mounted on the foot (46); and / or In order to detect, on two straight paths (TR), defects in the shape or positioning of a hollow body (2) passing through at least one of these paths (TR), the device comprises: - a first optical component (24) integrating an emitter, which generates a light beam (25) along a first light path, at least a section of which is oriented parallel to the first path (TR); - a first target (26) positioned remote from the first optical assembly (24), the first target (26) being provided with a reflector (27) or a light-sensitive sensor intercepting the first light path; - a second optical component (24) integrating an emitter which generates a light beam (25) along a second light path, at least a section of which is oriented parallel to the second path (TR); - a second target (26) positioned remote from the first optical assembly (24), the first target (26) being provided with a reflector (27) or a light-sensitive sensor intercepting the second light path; and / or The first optical component (24) is laterally offset from the first path (TR), the second optical component (24) is laterally offset from the second path (TR), and the device (23) includes an optical angle reflector positioned to orient the segment of the optical path parallel to the path (TR); and / or The optical component (24) is integrated with an optical bandpass filter having a passband centered on a predetermined wavelength; and / or The transmitter generates a light beam (25).

15. A conveyor belt (1) for transporting hollow bodies (2) of a thermal conditioning unit (7), said conveyor belt being equipped with a device (23) for detecting shape and position defects of hollow bodies (2) according to any one of claims 1 to 14.

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