METHOD FOR ASSEMBLING GRIPPING DEVICES ON A PREFORM CONVEYING DEVICE

Abstract

The invention relates to a method for mounting gripping elements (34B) of a preform conveying device (22) (12) which comprises: - mobile supports (32); - gripping elements (34B) stored in a storage magazine (52); the method comprising: - steps (E1) of transporting a gripping element (34B) by a robotic arm (46); - steps (E2) of mounting said gripping element (34B) thus transported onto the mobile support (32) by the robotic arm (46); - steps (E3) of automatically verifying the conformity of said gripping element (34B) by optical analysis using a device (60) with an optical sensor; characterized in that each step (E3) of verification of a gripping element (34B) is carried out before the start of step (E2) of mounting the next gripping element (34B) on its associated mobile support (32). Figure of the abstract: Figure 5.

Description

Title of the invention: METHOD FOR MOUNTING GRIPPING DEVICES ON A CONVEYING DEVICE PREFORMS TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to a method for mounting gripping devices for a heat-conditioning unit for preforms made of thermoplastic material, the heat-conditioning unit being equipped with a preform conveying device comprising: - mobile supports along a determined circuit passing through at least one preform heating zone and one assembly zone; - individual gripping elements of a preform which are capable of being removably mounted on an associated mobile support, each gripping element being capable of rotating on itself relative to the mobile support; - a storage facility for gripping devices; the process comprising: - at least one step of transporting a gripping device by a robotic arm from the storage store to the mobile support stopped in the assembly area; - at least one assembly step of said gripping member thus transported on the mobile support stopped in the assembly area by the robotic arm at least one automatic verification step of the conformity of said gripping member by optical analysis using an optical sensor device. TECHNICAL BACKGROUND OF THE INVENTION

[0002] The invention is intended to be implemented in a manufacturing plant for containers made of thermoplastic material, particularly polyethylene terephthalate (PET), by forming, notably by blow molding or stretch blow molding, preforms. Such a manufacturing plant makes it possible to produce containers in very large series at very high production rates.

[0003] Preforms are generally manufactured by injection molding at one location and then blow-molded into the final shape of the container at a second location on the manufacturing plant. This technology allows the blow-molding operation to be carried out as close as possible to the bottling site, while the injection molding operation can be performed anywhere. Indeed, it is relatively easy and inexpensive to transport small preforms, whereas transporting blow-molded containers has the disadvantage of being economically unsound. profitable due to their very large volume.

[0004] The preforms generally have a substantially cylindrical body of revolution with thick tubular walls, closed at one of its axial ends by a bottom, and extended at its other end by a neck, also tubular. The neck is formed to its final shape and dimensions while the body of the preform, previously heated, is intended to undergo a relatively large deformation to form it into a container during a forming step.

[0005] To enable its forming, the preform body is heated above a glass transition temperature, making the body wall malleable by significantly reducing its elastic limit. Conversely, the neck is maintained at a temperature below the glass transition temperature to prevent deformation. To this end, the manufacturing installation includes a thermal conditioning unit that heats the preform body to the temperature required for the forming step.

[0006] The heated preforms are then conveyed to a forming unit in the manufacturing plant. The hot preforms are automatically deposited into mold cavities by gripping devices such as grippers. Then, a pressurized forming fluid is injected into the preforms to press the preform wall against the cavity walls, thus shaping the preform into the final container. This forming operation is generally accompanied by a stretching operation, which involves inserting a stretching rod into the preform body to axially stretch the preform wall.

[0007] Throughout their journey through the manufacturing installation, the preforms are individually handled by conveying devices. Some of these conveying devices, particularly that of the thermal conditioning unit, include gripping elements.

[0008] The thermal conditioning unit includes heating means which are for example formed by infrared lamps in which the preform is moved by a conveyor system.

[0009] Gripping devices for conveying equipment passing through the heat conditioning unit are generally not simple clamps, as the gripping device must be able to rotate the object around an axis. To achieve this, the support generally includes a rotating element on which the gripping device is removably mounted.

[0010] Each gripping member is part of an element generally called a "turning nose" in reference to the inherent rotational movement of the gripping member. By way of non-limiting example, such turning noses may also be equipped with means for ejecting preforms.

[0011] Such a high-volume bottle manufacturing plant is very expensive. Therefore, the same manufacturing plant must be able to be used to produce bottles of varying sizes. In particular, the diameter of the preform necks is likely to vary depending on the bottle model to be manufactured.

[0012] To enable the handling of collars of different formats, it is known to change the gripping elements on the conveying devices.

[0013] However, the operation of changing the gripping devices is a tedious operation which requires stopping the manufacturing installation for a long time.

[0014] It is known that the changeover operation time can be reduced by using a robotic arm instead of an operator. Such a robotic arm can perform the various operations in a reduced time. In this case, the gripping elements are always brought one after the other into the replacement zone where the associated conveying element is immobilized while the robotic arm replaces the gripping element. The use of a robotic arm makes it possible to reduce the immobilization time of the conveying element in the replacement zone.

[0015] However, after the assembly of all the gripping devices on the conveying system, it remains necessary to verify that all the installed gripping devices are the correct size and that none are missing. Indeed, any error could damage the preforms, or even damage certain components of the manufacturing installation, for example, if a preform bursts due to a gripping device that is oversized relative to the preform's dimensions.

[0016] To this end, a verification step is planned for all gripping devices mounted on the conveying device before its restart in production mode.

[0017] The operation of changing gripping devices remains one of the most time-consuming operations to perform when changing a container model. It would therefore be advantageous to be able to further reduce its duration in order to reduce the overall production downtime of the manufacturing line. BRIEF SUMMARY OF THE INVENTION

[0018] The invention proposes a method for mounting gripping elements for a thermal conditioning unit for preforms made of thermoplastic material, the thermal conditioning unit being equipped with a preform conveying device which comprises: - mobile supports along a determined circuit passing through at least one preform heating zone and one assembly zone; - individual gripping devices of a preform which are capable of being removably mounted on an associated mobile support, each gripping device being capable of rotating on itself relative to the mobile support; - a storage store for gripping devices; the process comprising: - at least one step of transporting a gripping device by a robotic arm from the storage store to the mobile support stopped in the assembly area; - at least one assembly step by the robotic arm of said gripping device thus transported on the mobile support stopped in the assembly area and devoid of gripping device; - at least one automatic conformity verification step of said gripping member by optical analysis using an optical sensor device; characterized in that each verification step of a gripping member is carried out before the start of the mounting step of the next gripping member on its associated mobile support.

[0019] According to another feature of the method carried out according to the teachings of the invention, each verification step of a gripping member is carried out prior to the assembly step of said second gripping member.

[0020] According to another feature of the method carried out according to the teachings of the invention, all the verification steps of each gripping member are carried out before the first step of mounting the gripping member on the conveying device.

[0021] According to another feature of the process carried out according to the teachings of the invention, all the verification steps are carried out in masked time while the thermal conditioning unit operates in a production mode during which first gripping members already equipping the conveying device continue to transport preforms to heat them in the heating zone.

[0022] According to another feature of the method carried out according to the teachings of the invention, each verification step of a gripping member is carried out after an assembly step of the previous gripping member.

[0023] According to another feature of the method carried out according to the teachings of the invention, each verification step is carried out by individual optical analysis of each gripping organ.

[0024] According to another feature of the method carried out according to the teachings of the invention, the optical analysis of a gripping member is carried out during the transport step of said gripping member by the robotic arm.

[0025] According to another feature of the method carried out according to the teachings of the invention, the optical analysis of a gripping member is carried out after its mounting step on the associated mobile support 32.

[0026] According to another feature of the method carried out according to the teachings of the invention, the optical analysis of a gripping organ is carried out before its step of transport while still arranged in the storage facility.

[0027] According to another feature of the method carried out according to the teachings of the invention, several verification steps are carried out by taking a single image by the optical sensor device simultaneously comprising several gripping members when they are arranged in the storage store.

[0028] According to another feature of the method carried out according to the teachings of the invention, each gripping member includes a marking incorporating the information necessary for the identification of its model, such as a one-dimensional or two-dimensional barcode.

[0029] According to another feature of the method carried out according to the teachings of the invention, the verification step includes an image recognition phase allowing the dimensions of the gripping organ to be determined directly.

[0030] The invention also relates to a thermal conditioning unit for implementing the process carried out according to the teachings of the invention, comprising a robotic arm capable of grasping at least one gripping member to transport it to an associated mobile support of a preform conveying device, characterized in that the robotic arm is equipped with an optical sensor device enabling the implementation of the verification step. BRIEF DESCRIPTION OF THE FIGURES

[0031] Other features and advantages of the invention will become apparent during the reading of the detailed description which follows, for the understanding of which reference will be made to the attached drawings briefly described below.

[0032] Fig. 1 is a top view that schematically represents an ins plant for manufacturing containers comprising a thermal conditioning unit capable of implementing the process carried out according to the teachings of the invention.

[0033] Fig.2 is a cross-sectional view along section plane 2-2 of Fig.1, which represents two movable supports of a conveying device equipping the thermal conditioning unit of Fig.1, one of the supports being equipped with a gripping member while the gripping member of the other of the supports is disassembled.

[0034] Fig. 3 is a larger-scale top view of the device Conveyance of the [Fig.l] representing a robotic arm enabling the mounting of gripping devices on the mobile supports of the transport device.

[0035] Fig.4 is a perspective view that schematically represents the robotic arm of Fig.3 equipped with a manipulation head capable of grasping a grasping organ and which is equipped with an optical sensor device to implement the process carried out according to the teachings of the invention.

[0036] Fig.5 is a cross-sectional view representing the manipulation head of the robotic arm of Fig.4 which grasps a gripping member to mount it on an associated mobile support.

[0037] Fig. 6 is a block diagram representing the method of mounting the gripping devices according to a first embodiment of the invention.

[0038] Fig.7 is a block diagram that represents the method of mounting the gripping devices according to a second embodiment of the invention.

[0039] Figure 8 is a block diagram representing the method of assembling the gripping elements according to a third embodiment of the invention. DETAILED DESCRIPTION OF THE FIGURES

[0040] In the following description, elements having an identical structure or analogous functions will be designated by the same references.

[0041] In the remainder of this description, a local coordinate system for each moving support will be adopted, without limitation, comprising a longitudinal direction "L", directed from back to front along the direction of movement of the moving supports, a vertical direction "V", directed from bottom to top, and a transverse direction "T" which is perpendicular to the two preceding directions. The vertical direction is used here as a geometric coordinate system unrelated to the direction of Earth's gravity.

[0042] In the rest of the description, the terms "upstream" and "downstream" will be used in reference to the direction of movement of the mobile supports.

[0043] Figure 1 shows part of an automated, high-volume manufacturing installation 10 for containers made of thermoplastic material such as polyethylene terephthalate (PET). The manufacturing installation 10 is designed to form containers from preforms 12 that are heated.

[0044] The manufacturing installation 10 comprises several processing units. Figure 1 shows, in particular, a thermal conditioning unit 14 for the preforms 12 and, very schematically, a forming unit 16, here by blow molding or stretch-blow molding, for the preforms 12 previously heated by said thermal conditioning unit 14. It will be understood that the manufacturing installation 10 may also include decontamination units for the preforms 12, or other processing units well known to those skilled in the art for this type of application.

[0045] With reference to [Fig. 2], each preform 12 comprises a tubular body 12A extending along a principal axis, shown here vertically. The body 12A has a closed bottom 12C at its lower end. The preform 12 has a neck 12B arranged axially upwards in line with the body 12A. The neck 12B has a collar 12D at its junction with the body 12A. The body 12A is open upwards via the neck 12B. Generally, only the body 12A of The preform 12 is intended to be heated and stretched to form the final container. The neck 12B of the preform 12 already has its final shape. Therefore, the neck 12B is kept at a sufficiently low temperature in the heat conditioning unit 14 to prevent deformation during container manufacturing. Consequently, the preform 12 is conveyed through the heat conditioning unit 14 by grasping it by its neck 12B.

[0046] Referring again to [Fig. 1], the heat conditioning unit 14 comprises at least one heating zone 18 equipped with radiation emitters 20 that heat the body 12A of the preforms 12. The heating zone 18 is bordered by a series of adjacent radiation emitters 20, for example, two rows of radiation emitters 20 facing each other. The radiation emitters 20 are, for example, laser diodes or halogen lamps. The heating radiation is, by way of non-limiting example, infrared radiation.

[0047] The thermal conditioning unit 14 also includes a preform conveying device 22 for the preforms 12, which is designed to convey each preform 12 along a heating path that passes through the heating zone 18. The preforms 12 thus move one after the other along the path.

[0048] The path of the preforms 12 extends in the conveying device 22 from a loading point 24 to an unloading point 26. The cold preforms 12 are conveyed one after the other to the loading point 24 by a preform distribution device 12, here a notched wheel 28. The hot preforms 12 are transferred to a transfer wheel 30 when they arrive at the unloading point 26. The transfer wheel 30 then transports the hot preforms 12 to the forming unit 16.

[0049] As shown in [Fig. 3], the preform conveying device 22 12 includes mobile supports 32 which are guided in movement in a line along a determined circuit 33, which here extends in a horizontal plane.

[0050] These mobile supports 32 can be articulated together to form a closed chain which is set in motion by meshing with drive wheels, or they can be independent of each other and each driven individually into motion by a linear motor.

[0051] The conveying device 22 further comprises first preform gripping elements 34A 12, each of which is removably mounted on a connecting element 36 associated with a movable support 32.

[0052] Each movable support 32 may include one or more connecting elements 36, for example two or three. In the example shown in [Fig. 3], the movable support 32 includes one connecting element 36.

[0053] Each first grasping organ 34A is capable of individually carrying a preform 12 by its neck 12B. As shown in [Fig.2], this is for example a mandrel which has a central vertical axis "A" coaxial with the main axis of the preform 12 which it carries.

[0054] This is for example a mandrel which is inserted inside the neck 12B of the preform 12 and whose jaws 35 are likely to occupy an expanded position in which they are radially supported against an internal wall of the neck 12B.

[0055] In an alternative not shown, it is a mandrel which is able to clamp the collar 12B by its external face.

[0056] In a conveying device 22 for a thermal conditioning unit 14, the connecting element 36 is rotatably mounted in the support 32, which is movable about an axis coaxial with the axis "A" of the preform 12 transported by the first gripping member 34A. Since the first gripping member 34A is rotatably mounted with the connecting element 36, this allows the transported preform 12 to rotate about its axis "A". Thus, the entire body 12A of the preform 12 can be exposed to the heating radiation as it passes through the heating zone 18. Rotation is achieved, for example, by means of a pinion 37 fitted to the connecting element 36.

[0057] The mobile supports 32 thus transport the first gripping organs 34A in a line along the conveying circuit 33.

[0058] The conveying circuit 33 here has the form of a closed loop which is traversed in one direction, here a counterclockwise direction with reference to [Fig. 1], by the movable supports 32. Thus, each movable support 32 can take charge of a new cold preform 12 during a new cycle after having transferred a hot preform 12 to the unloading point 26.

[0059] Each first gripping member 34A is removably mounted on the associated connecting element 36 by means of quick-release assembly means 39. These assembly means 39 are designed so that each first gripping member 34A can be automatically removed from the connecting element 36 on which it is mounted by means of removal, in particular to be replaced by second gripping members 34B. Similarly, each second gripping member 34B can be automatically mounted on the connecting element 36 of a movable support 32 by means of reassembly.

[0060] By way of non-limiting example, each gripping member 34A, 34B is here mounted on a connecting element 36 of the movable support 32 by elastic interlocking along a sliding direction "D" between an interlocked position, shown on the left of [Fig. 2], and an uninterlocked position, shown on the right of [Fig. 2]. The sliding direction "D" is here parallel to the vertical axis "A" of the gripping member 34A, 34B. To this end, the gripping member 34A, 34B comprises a first element 42 the interlocking element which is intended to be interlocked with a second interlocking element 44 of complementary shape carried by the connecting element 36. Thus, the interlocking and uninterlocking operations can be carried out by moving the gripping member 34A, 34B and the connecting element 36 relative to each other along the sliding direction "D" either in an interlocking direction or in the opposite uninterlocking direction.

[0061] In the embodiment shown in [Fig.2], the first interlocking element 42 is formed by a male element, here a rod with a vertical axis, and the second interlocking element 44 is formed by a housing of complementary shape.

[0062] In an alternative not shown, the first interlocking element is formed by a housing and the second interlocking element is formed by a complementary male element.

[0063] As illustrated in [Fig. 3], the manufacturing installation 10 is equipped with a robotic arm 46 to successively perform the assembly and disassembly operations of gripping components 34A, 34B. According to such a known arrangement, each movable support 32 is immobilized in an assembly zone 48 of the conveyor circuit 33, to temporarily stop the movable support 32. The robotic arm 46 is arranged near the assembly zone 48.

[0064] During its stop, the first gripping element 34A, which equips said mobile support 32, is removed by the robotic arm 46, and then a second gripping element 34B is mounted on said mobile support 32 by the robotic arm 46. The robotic arm 46 also transports the first removed gripping element 34A to a storage location 50 and also brings the second gripping element 34B to replace it from an external storage location 52.

[0065] Such robotic arms 46 are well known, and they will not be described in further detail hereafter. They are generally six-degree-of-freedom arms, known as six-axis arms.

[0066] As shown in [Fig. 4], the robotic arm 46 comprises a manipulation head 54 equipped with at least one gripper 58 capable of grasping a gripping element 34A, 34B. The gripper 58 supports the gripping element 34A, 34B to allow for its transport, assembly, and disassembly.

[0067] Generally, each gripping member 34A, 34B is mounted on its mobile support 32 by interlocking caused by the movement of the gripper 58 carrying said gripping member 34A, 34B along the "D" direction of sliding relative to the stopped mobile support 32, as shown in [Fig.5].

[0068] In an unshown variant of the invention, where the gripping members 34A, 34B have a locking mechanism in the mounted position, the handling head 54 is also equipped with an actuator for unlocking each member 34A, 34B gripping. The unlocking actuator is capable of actuating the locking mechanism.

[0069] In an alternative embodiment of the invention, the dismantling operation is carried out in a first dismantling zone of the conveyor circuit, while the reassembly operation is carried out in a second assembly zone 48 of the conveyor circuit 33, which is arranged downstream of the first dismantling zone according to the direction of movement of the mobile supports 32. In this case, the manufacturing installation 10 comprises two robotic arms equipped with a gripper 58. One of the arms is arranged near the first dismantling zone to dismantle the first gripping elements 34A and store them in an associated storage location 50, while the other arm is arranged near the second assembly zone 48 to retrieve the second gripping elements 34B from the associated storage magazine 52 and mount them onto each mobile support 32.

[0070] In an unshown embodiment of the invention, the storage location for the first gripping elements 34A is formed by the storage magazine 52 for the second gripping elements 34B. In this case, the storage magazine 52, when all the second gripping elements 34B are stored in it, has an additional free space. When a first gripping element 34A is removed, it is stored in this additional free space, and then a second gripping element 34B is taken from the storage magazine to be mounted on the movable support 32 from which the first gripping element 34A has just been removed. This creates a new free space to accommodate the next first gripping element 34A to be removed. This embodiment is particularly suitable when the gripping elements 34A and 34B are replaced one after the other.This helps to reduce the size of the device and lower the production costs of the installation.

[0071] During a change of the first gripping members 34A, a method is implemented for mounting each second gripping member 34B automatically on an associated mobile support 32 after the first gripping member 34A has been removed from said mobile support 32.

[0072] The assembly method is also applicable to a conveying device 22 on which no gripping member has yet been mounted. In this case, all the movable supports 32 are without first gripping members 34A.

[0073] The assembly process comprises: - at least one "El" transport step of each second gripping organ 34B by the robotic arm 46 from the storage store 52 to the mobile support 32 stopped in the assembly area 48; - at least one "E2" assembly step for each second gripping element 34B thus transported on the mobile support 32 stopped in the assembly zone 48 by robotic arm 46.

[0074] These steps "E1, E2" are carried out successively for each second grasping organ 34B. The second grasping organs 34B are thus mounted successively one after the other.

[0075] Prior to these steps "E1, E2", the storage unit 52 can be brought to the vicinity of the assembly area 48. For this purpose, the storage unit 52 is, for example, mounted on casters or it can be transported by a suitable vehicle.

[0076] To perform these transport and assembly steps "E1, E2", the thermal conditioning unit 14 switches from a production mode to a maintenance mode. In production mode, the first gripping devices 34A transport preforms 12 to the thermal conditioning unit 14 to be heated before being transferred to the forming unit 16. In maintenance mode, the thermal conditioning unit 14 is no longer supplied with preforms 12 in order to interrupt the movement of the mobile supports 32 at each assembly step "E2".

[0077] During the assembly process, a mobile support 32 without a gripping element is temporarily stopped in the assembly area 48. Step "El" of transporting a second gripping element 34B is implemented to transport the second gripping element 34B to the stopped mobile support 32. This transport step "El" is directly followed by step "E2" of mounting the second gripping element 34B onto the stopped mobile support 32 to which it was transported. During these two transport and mounting steps "El, E2", the second gripping elements 34B are automatically transported and mounted by the robotic arm 46 positioned near the circuit assembly area 48.

[0078] Following the assembly step "E2", the mobile support 32 equipped with the second gripping member 34B is moved downstream, while a subsequent mobile support 32, which is not yet equipped with a second gripping member 34B, is brought into the assembly zone 48. The process is then repeated for the next second gripping member 34B in order to mount it onto the next mobile support 32. The process is repeated until all the mobile supports 32 are equipped with a second gripping member 34B.

[0079] It is known to visually verify that each second gripping member 34B thus mounted is indeed adapted to the preform model 12 which will be processed by the manufacturing installation 10. To this end, the process includes at least one step "E3" of automatic verification of the conformity of the second gripping members 34B by analyzing an image taken by an optical sensor device 60.

[0080] According to the teachings of the invention, each step "E3" of verification of a second gripping member 34B is carried out before the start of step "E2" of mounting the second subsequent gripping member 34B on the movable support 32 associated. This saves time by avoiding the need to search for the position of a second non-compliant 34B gripping element after all the second 34B gripping elements have been installed.

[0081] Preferably, each "E3" verification step of a second gripping member 34B is carried out prior to the "E2" mounting step of said second gripping member 34B. This allows for faster identification of any non-conformity even before the second gripping member 34B is mounted on its movable support 32. This saves time.

[0082] To achieve this, the optical sensor device 60 is advantageously arranged on the robotic arm 46. For example, it is arranged on the manipulation head 54 of the robotic arm 46. The optical sensor device 60 enables optical analysis of each second gripping organ 34B.

[0083] The optical sensor device 60 is, for example, a camera or a photographic device. The optical sensor device 60 thus advantageously allows for capturing an image in a digital format that can be easily analyzed by suitable computer software.

[0084] According to a first embodiment of each "E3" verification step, the optical analysis of each second gripping organ 34B is carried out by recognition of a visual mark 61 carried by each of the gripping organs 34A, 34B by means of the optical sensor device 60.

[0085] For example, this could be a barcode or a matrix code, such as a QR code, applied to each of the gripping elements 34A, 34B. This code may appear on each of the images taken by the optical sensor device 60. This image is transmitted to an electronic unit capable of identifying and reading the information contained in this code. The code itself may directly contain the dimensions of the gripping element 34A, 34B.

[0086] Alternatively, the optical sensor device 60 can also be formed by a barcode or two-dimensional code reader. In this case, the optical analysis is performed by reading the marking directly on the second gripping member 34B by means of the optical sensor device 60.

[0087] Alternatively, the code contains a reference number for the gripping element. The electronic control unit then includes a pre-recorded database allowing each reference number to be matched to a particular model of the gripping element.

[0088] According to a second embodiment of the verification step "E3", the optical analysis of each second gripping organ 34B is performed by taking an image and then determining the dimensions of the gripping organ 34A, 34B by pattern recognition on the image of said gripping organ 34A, 34B taken by the optical sensor device 60. For example, the electronic control unit measures certain dimensions of the gripping element 34A, 34B on the image in order to check its conformity. For example, the external diameter of the gripping element 34A, 34B is measured to ensure that it corresponds to the internal diameter of the neck 12B of the preforms 12 that are to be processed subsequently.

[0089] According to a first embodiment of the process, all the "E3" steps of checking the second gripping members 34B are carried out before the first "El" step of transporting the second gripping members 34B, when all the second gripping members 34B are still stored in the storage store 52.

[0090] For example, each verification step "E3" is performed successively for each second gripping element 34B by individual analysis of each second gripping element 34B. In this case, the robotic arm 46 passes the optical sensor device 60 in front of each second gripping element 34B. Step "E3" is therefore repeated until all second gripping elements 34B have been analyzed, as indicated by condition "Cl" in [Fig. 6].

[0091] Alternatively, several "E3" verification steps are carried out by taking a single image simultaneously containing several second grasping organs 34B when they are arranged in the storage magazine 52.

[0092] By proceeding in this way, it is possible to carry out all the "E3" verification steps in masked time while the thermal conditioning unit 14 is operating in a production mode, as indicated by block "Bl" in [Fig.6]. This makes it possible to shorten the time during which the thermal conditioning unit 14 is in maintenance mode.

[0093] Next, the transport and assembly steps "El", "E2" are carried out for each second gripping member 34B up to the last one, as indicated by condition "C2" of [Fig.6].

[0094] Only the "El, E2" transport and assembly steps are carried out while the manufacturing installation 10 is in maintenance mode, as indicated by block "B2" of [Fig.6],

[0095] According to a second embodiment of the invention, each verification step "E3" of a second gripping element 34B is performed after a step "E2" of mounting the second gripping element 34B onto the preceding mobile support 32. Thus, after the mounting step "E2" of a second gripping element 34B, the robotic arm 46 retrieves a subsequent second gripping element 34B from the storage magazine 52 to transport it and then fix it onto its mobile support 32 in the mounting area 48.

[0096] In this case, each verification step "E3" is carried out by optical analysis. visual of each second grasping organ 34B.

[0097] This individual optical analysis can be performed while the second gripping element 34B is still arranged in the storage magazine 52, just before the manipulation head 54 of the robotic arm 46 grasps it, as shown in [Fig. 7]. Thus, the verification step "E3" is carried out before the second gripping element 34B is grasped by the robotic arm 46. This avoids having to replace the second gripping element 34B if it is non-conforming.

[0098] In an alternative shown in [Fig. 8], the optical analysis of the second gripping element 34B is performed during the "El" transport step of said second gripping element 34B by the robotic arm 46. Thus, the verification step "E3" is performed in the background during the transport step "El".

[0099] According to another variant not shown, the optical analysis of the second gripping organ 34B is taken after its "E2" mounting step on an associated mobile support 32.

[0100] According to a variant of this second embodiment of the invention, each second gripping member 34B is individually identified, for example by a reference number. This reference number is, for example, indicated by a marking on the second gripping member 34B. This reference number can be identified during the analysis of the image taken by the optical sensor device 60.

[0101] This allows the usage time of each second gripping member 34B to be tracked, in particular to anticipate maintenance operations on said second gripping member 34B.

Claims

Claims

1. Method for mounting gripping members (34B) for a unit (14) for thermally conditioning preforms (12) made of thermoplastic material, the thermal conditioning unit (14) being equipped with a device (22) for conveying preforms (12) which comprises: - supports (32) movable along a determined circuit (33) passing through at least one zone (18) for heating the preforms (12) and a mounting zone (48); - members (34B) for individual gripping of a preform (12) which are capable of being removably mounted on an associated movable support (32), each gripping member (34B) being capable of rotating on itself relative to the movable support (32); - a magazine (52) for storing the gripping members (34B);the method comprising: - at least one step (E1) of transporting a gripping member (34B) by a robotic arm (46) from the storage magazine (52) to the mobile support (32) stopped in the assembly zone (48); - at least one step (E2) of mounting by the robotic arm (46) of said gripping member (34B) thus transported on the mobile support (32) stopped in the assembly zone (48) and devoid of gripping member; - at least one step (E3) of automatically verifying the conformity of said gripping member (34B) by optical analysis using an optical sensor device (60); characterized in that each step (E3) of verifying a gripping member (34B) is carried out before the start of the step (E2) of mounting the next gripping member (34B) on its associated mobile support (32).;

2. Method according to the preceding claim, characterized in that each step (E3) of verifying a gripping member (34B) is carried out prior to the step (E2) of mounting said second gripping member (34B).

3. Method according to the preceding claim, characterized in that all the steps (E3) of verifying each gripping member (34B) are carried out before the first step (E2) of mounting the gripping member (34B) on the conveying device (22).

4. Method according to the preceding claim, characterized in that all the verification steps (E3) are carried out in masked time during that the thermal conditioning unit (14) operates in a production mode in which first gripping members (34A) already equipping the conveying device (22) continue to transport preforms (12) to heat them in the heating zone (18).

5. Method according to claim 1, characterized in that each step (E3) of verifying a gripping member (34B) is carried out after a step (E2) of mounting the previous gripping member (34B).

6. Method according to any one of the preceding claims, characterized in that each verification step (E3) is carried out by individual optical analysis of each gripping member (34B).

7. Method according to claim 6, characterized in that the optical analysis of a gripping member (34B) is carried out during the step (El) of transporting said gripping member (34B) by the robotic arm (46).

8. Method according to claim 6, characterized in that the optical analysis of a gripping member (34B) is carried out after its step (E2) of mounting on the associated mobile support 32.

9. Method according to any one of claims 6 or 7, characterized in that the optical analysis of a gripping member (34B) is carried out before its transport step (El) when it is still arranged in the storage magazine (52).

10. Method according to any one of claims 1 to 5, characterized in that several verification steps (E3) are carried out by taking a single image by the optical sensor device (60) simultaneously comprising several gripping members (34B) when they are arranged in the storage magazine (52).

11. Method according to any one of the preceding claims, characterized in that each gripping member (34B) comprises a marking incorporating the information necessary for the identification of its model, such as a one-dimensional or two-dimensional bar code.

12. Method according to any one of the preceding claims, characterized in that the verification step (E3) comprises an image recognition phase making it possible to directly determine the dimensions of the gripping member (34B).

13. Thermal conditioning unit (14) for implementing the method according to any one of the preceding claims, comprising a robotic arm (46) capable of gripping at least one gripping member (34B) to transport it to an associated mobile support (32) of a preform conveying device (22), characterized in that the robotic arm (46) is equipped with an optical sensor device (60) allowing the implementation of the verification step (E3).