Method for mounting gripping members on a device for conveying preforms

Abstract

The invention relates to a method for mounting gripping members (34B) of a device (22) for conveying preforms (12) which comprises: - movable supports (32); - gripping members (34B) stored in a storage facility (52); the method comprising: - steps (E1) of transporting a gripping member (34B) by means of a robotic arm (46); - steps (E2) of mounting the gripping member (34B) thus transported on the movable support (32) by means of the robotic arm (46); - steps (E3) of automatically verifying the conformity of the gripping member (34B) by optical analysis by means of a device (60) having an optical sensor. The invention is characterised 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 movable support (32).

Description

METHOD FOR MOUNTING GRIPPING MEANS ON A PREFORM CONVEYOR DEVICE TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to a method for mounting gripping members for a unit for thermally conditioning preforms made of thermoplastic material, the thermal conditioning unit being equipped with a preform conveying device which comprises: - supports movable along a determined circuit passing through at least one preform heating zone and a mounting zone; - individual gripping members of a preform which are capable of being removably mounted on an associated movable support, each gripping member being capable of rotating on itself relative to the movable support; - a magazine for storing the gripping members; the method comprising: - at least one step of transporting a gripping member by a robotic arm from the storage magazine to the movable support stopped in the mounting zone;- at least one step of mounting said gripping member thus transported onto the mobile support stopped in the mounting zone by the robotic arm; - at least one step of automatic verification 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 an installation for manufacturing containers made of thermoplastic material and in particular polyethylene terephthalate (PET) by forming, in particular by blowing or stretch-blow molding, preforms. Such a manufacturing installation makes it possible to produce containers in very large series at very high rates.

[0003] Preforms are generally manufactured by injection at one location and are blow-molded to the final container shape at a second location on the manufacturing facility. Such technology allows the blow-molding operation to be carried out as close as possible to the bottling site, with the injection operation being able to be carried out at any location. Indeed, it is relatively easy and inexpensive to transport small preforms, while transporting containers after blowing has the disadvantage of being economically unprofitable due to their very large volume.

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

[0005] To enable its forming, the body of the preform is heated beyond a glass transition temperature making the wall of the body malleable by significantly reducing its elastic limit. On the contrary, the neck is kept at a temperature below the glass transition temperature to prevent its deformation. For this purpose, the manufacturing facility includes a thermal conditioning unit which allows the body of the preforms to be heated to the temperature required to carry out the forming step.

[0006] The preforms thus heated are then conveyed to a forming unit in the manufacturing facility. The hot preforms are automatically placed in mold cavities by gripping devices such as clamps. Then, a pressurized forming fluid is injected into the preforms to press the wall of the preform against the walls of the cavity to conform the preform into the final container. This forming operation is generally accompanied by a stretching operation consisting of introducing an elongation rod into the preform through its body in order to axially stretch the wall of the preform.

[0007] Throughout their journey through the manufacturing facility, the preforms are individually handled by conveyor devices. Some of these conveyor devices, particularly the one in the thermal conditioning unit, include gripping devices.

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

[0009] Grippers for conveyor devices passing through the thermal conditioning unit are generally not simple clamps because the gripper must be able to drive the object in rotation around an axis. To achieve this, the support generally includes a rotating element on which the gripper is removably mounted.

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

[0011] Such a large-scale bottle manufacturing facility is very expensive. Therefore, the same manufacturing facility must be able to manufacture bottles of various sizes. The diameter of the preform necks is likely to vary depending on the bottle model to be manufactured.

[0012] To allow the gripping of necks of different formats, it is known to change the gripping members on the conveyor devices.

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

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

[0015] However, after the operation of mounting all the gripping members on the conveyor device, it is still necessary to check that all the gripping members that have been installed have the correct dimensions and that no gripping members are missing. Indeed, if an error is made, this risks damaging the preforms, or even damaging certain elements of the manufacturing installation, for example if a preform bursts due to a gripping member that is oversized compared to the dimensions of the preform.

[0016] For this purpose, a verification step is planned for all the gripping devices mounted on the conveyor device before it is restarted in production mode.

[0017] The operation of changing gripping devices remains one of the most time-consuming operations to be carried out when changing container models. It would therefore be advantageous to be able to further reduce its duration in order to reduce the duration of production shutdown of the entire production line. BRIEF SUMMARY OF THE INVENTION

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

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

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

[0021] According to another characteristic of the method 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 characteristic of the method carried out according to the teachings of the invention, each step of verifying a gripping member is carried out after a step of mounting the previous gripping member.

[0023] According to another characteristic 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 member.

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

[0025] According to another characteristic 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 characteristic of the method carried out according to the teachings of the invention, the optical analysis of a gripping member is carried out before its transport step when it is still arranged in the storage magazine.

[0027] According to another characteristic 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 magazine.

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

[0029] According to another characteristic of the method carried out according to the teachings of the invention, the verification step comprises an image recognition phase making it possible to directly determine the dimensions of the gripping member.

[0030] The invention also relates to a thermal conditioning unit for implementing the method carried out according to the teachings of the invention, comprising a robotic arm capable of gripping 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 provided with an optical sensor device allowing the verification step to be implemented. BRIEF DESCRIPTION OF THE FIGURES

[0031] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which one will refer to the appended drawings briefly described below.

[0032] This is a top view which schematically represents a container manufacturing installation comprising a thermal conditioning unit capable of implementing the method carried out according to the teachings of the invention.

[0033] This is a sectional view along section plane 2-2 of which shows two mobile supports of a conveyor device equipping the thermal conditioning unit of the, one of the supports being equipped with a gripping member while the gripping member of the other of the supports is dismantled.

[0034] This is a larger-scale top view of the conveyor device representing a robotic arm allowing the mounting of gripping members on the mobile supports of the transport device.

[0035] This is a perspective view which schematically represents the robotic arm of the equipped with a manipulation head capable of gripping a gripping member and which is equipped with an optical sensor device for implementing the method carried out according to the teachings of the invention.

[0036] This is a sectional view showing the manipulation head of the robotic arm which grasps a gripping member to mount it on an associated mobile support.

[0037] This is a block diagram which represents the method of mounting the gripping members carried out according to a first embodiment of the invention.

[0038] This is a block diagram which represents the method of mounting the gripping members carried out according to a second embodiment of the invention.

[0039] This is a block diagram which represents the method of mounting the gripping members carried out according to a third embodiment of the invention. DETAILED DESCRIPTION OF THE FIGURES

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

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

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

[0043] A part of an installation 10 for the automatic mass production of containers made of thermoplastic material such as polyethylene terephthalate (PET) is shown. The manufacturing installation 10 is here intended to form containers from preforms 12 to be heated.

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

[0045] With reference to the, each preform 12 comprises a tubular body 12A which extends along a main axis, shown here vertically. The body 12A comprises at its lower end a closed bottom 12C. The preform 12 comprises a neck 12B which is arranged in the extension of the body 12A axially upwards. The neck 12B comprises here, at its junction with the body 12A, a flange 12D. 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. In this regard, the neck 12B is maintained at a sufficiently low temperature in the thermal conditioning unit 14 to prevent it from deforming during the manufacture of the container. As a result, the preform 12 is transported through the thermal conditioning unit 14 by gripping it by its neck 12B.

[0046] Referring again to the, the thermal conditioning unit 14 comprises at least one heating zone 18 provided with radiation emitters 20 heating 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 comprises a device 22 for conveying the preforms 12 which is intended to convey each preform 12 along a heating path which passes through the heating zone 18. The preforms 12 thus pass one behind 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 the, the device 22 for conveying preforms 12 comprises movable supports 32 which are guided in movement in a row along a determined circuit 33, which here extends in a horizontal plane.

[0050] These movable supports 32 can be hinged 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 individually driven into motion by a linear motor.

[0051] The conveying device 22 further comprises first members 34A for gripping preforms 12, each of which is removably mounted on an associated connecting element 36 of a mobile support 32.

[0052] Each movable support 32 may comprise a connecting element 36 or several connecting elements 36, for example two or three. In the example shown in , the movable support 32 comprises a connecting element 36.

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

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

[0055] In a variant not shown, this is a mandrel which is capable of clamping the neck 12B by its external face.

[0056] In the case of a device 22 for conveying a thermal conditioning unit 14, the connecting element 36 is mounted for rotation in the movable support 32 about an axis coaxial with the axis "A" of the preform 12 transported by the first gripping member 34A. The first gripping member 34A being mounted integral in rotation with the connecting element 36, this makes it possible to drive the transported preform 12 in rotation about its axis "A". Thus, the entire body 12A of the preform 12 can be exposed to the heating radiation during its passage in the heating zone 18. The rotation is for example carried out by means of a pinion 37 which equips the connecting element 36.

[0057] The mobile supports 32 thus transport the first gripping members 34A in a row along the conveyor circuit 33.

[0058] The conveying circuit 33 here has the form of a closed loop which is traveled in one direction, here a counterclockwise direction with reference to the, by the mobile supports 32. Thus, each mobile 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 quick assembly means 39. These assembly means 39 are designed so that each first gripping member 34A can be automatically dismantled from the connecting element 36 on which it is mounted by dismantling means, 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 mobile support 32 by reassembly means.

[0060] As a non-limiting example, each gripping member 34A, 34B is here mounted on a connecting element 36 of the movable support 32 by elastic fitting in a sliding direction "D" between a fitted position, shown on the left of the, and a disengaged position, shown on the right of the. The sliding direction "D" is here parallel to the vertical axis "A" of the gripping member 34A, 34B. For this purpose, the gripping member 34A, 34B comprises a first fitting element 42 which is intended to be fitted with a second fitting element 44 of complementary shape carried by the connecting element 36. Thus, the nesting and unnesting operations can be carried out by moving the gripping member 34A, 34B and the connecting element 36 relative to each other in the sliding direction "D" either in a nesting direction or in an opposite unnesting direction.

[0061] In the embodiment shown in , 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 a variant 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 the, the manufacturing installation 10 is equipped with a robotic arm 46 for successively carrying out the operations of mounting and dismounting gripping members 34A, 34B. According to such a known arrangement, each mobile support 32 is immobilized in an assembly zone 48 of the conveyor circuit 33, to temporarily stop the mobile support 32. The robotic arm 46 is arranged close to the assembly zone 48.

[0064] During its stoppage, the first gripping member 34A which equips said mobile support 32 is dismantled by the robotic arm 46, then a second gripping member 34B is mounted on said mobile support 32 by the robotic arm 46. The robotic arm 46 also takes care of transporting the dismantled first gripping member 34A to a storage location 50 and it also takes care of bringing the second gripping member 34B to replace it from an external storage magazine 52.

[0065] Such robotic arms are well known and will not be described in more detail below. They are generally arms with six degrees of freedom, known as six-axis arms.

[0066] As shown in , the robotic arm 46 comprises a handling head 54 which is equipped with at least one gripper 58 which is capable of gripping a gripping member 34A, 34B. The gripper 58 supports the gripping member 34A, 34B to enable it to be transported, assembled and disassembled.

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

[0068] In a variant of the invention not shown, when the gripping members 34A, 34B comprise a locking mechanism in the mounted position, the handling head 54 is also equipped with an actuator for unlocking each gripping member 34A, 34B. The unlocking actuator is capable of actuating the locking mechanism.

[0069] In a variant of the invention that is not shown, the disassembly operation is carried out in a first disassembly 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 disassembly zone in the direction of movement of the movable 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 disassembly zone to disassemble the first gripping members 34A and store them in an associated storage location 50, while the other of the arms is arranged near the second assembly zone 48 to take the second gripping members 34B from the associated storage magazine 52 and mount them on each movable support 32.

[0070] In a variant of the invention not shown, the storage location of the first gripping members 34A is formed by the magazine 52 for storing the second gripping members 34B. In this case, the storage magazine 52, when all the second gripping members 34B are stored there, has an additional free location. When a first gripping member 34A is dismantled, the latter is stored in the additional free location, then a second gripping member 34B is taken from the storage magazine to be mounted on the movable support 32 from which the first gripping member 34A has just been dismantled. This creates a new free location to accommodate the next first gripping member 34A which will be dismantled. This variant is particularly suitable when the gripping members 34A, 34B are replaced one after the other.This makes it possible, in particular, to reduce the size of the device and to lower the production costs of the installation.

[0071] When changing 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 devoid of first gripping members 34A.

[0073] The assembly method comprises:- at least one step "E1" of transporting each second gripping member 34B by the 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 each second gripping member 34B thus transported onto the mobile support 32 stopped in the assembly zone 48 by the robotic arm 46.

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

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

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

[0077] When implementing the assembly method, a mobile support 32 without a gripping member is temporarily stopped in the assembly area 48. The step "E1" of transporting a second gripping member 34B is implemented to transport the second gripping member 34B to said stopped mobile support 32. This transport step "E1" is directly followed by the step "E2" of mounting said second gripping member 34B on the stopped mobile support 32 to which it was transported. During these two transport and assembly steps "E1, E2", the second gripping members 34B are transported and mounted automatically by the robotic arm 46 arranged near the circuit assembly area 48.

[0078] At the end of the assembly step "E2", the movable support 32 equipped with the second gripping member 34B is moved downstream while a following movable support 32 which is not yet equipped with a second gripping member 34B is brought into the assembly zone 48. The method is then repeated for the following second gripping member 34B in order to mount it on said following movable support 32. The method is repeated until all the movable 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 well adapted to the preform model 12 which will be processed by the manufacturing installation 10. To this end, the method comprises at least one step "E3" of automatic verification of the conformity of the second gripping members 34B by analysis of an image taken by a device 60 with an optical sensor.

[0080] According to the teachings of the invention, each step "E3" of verifying a second gripping member 34B is carried out before the start of step "E2" of mounting the next second gripping member 34B on the associated mobile support 32. This thus saves time by avoiding having to search for the position of a non-compliant second gripping member 34B after installation of all the second gripping members 34B.

[0081] Preferably, each step "E3" of verifying a second gripping member 34B is carried out prior to step "E2" of mounting said second gripping member 34B. Thus, it is possible to identify more quickly any non-conformity even before mounting the second gripping member 34B on its movable support 32. This saves time.

[0082] To do this, the optical sensor device 60 is advantageously arranged on the robotic arm 46. It is for example arranged on the manipulation head 54 of the robotic arm 46. The optical sensor device 60 allows an optical analysis of each second gripping member 34B.

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

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

[0085] For example, it is a bar code or a matrix code, such as a QR code, which is applied to each of the gripping members 34A, 34B. This code is likely to appear on each of the images taken by the optical sensor device 60. This image is transmitted to an electronic unit which is able to identify and read the information contained on this code. The code may in itself directly contain the dimensions of the gripping member 34A, 34B.

[0086] Alternatively, the optical sensor device 60 may also be formed by a barcode or two-dimensional code reader. In this case, the optical analysis is carried out 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 of the gripping member. The electronic control unit then has a pre-stored database allowing each reference number to be matched to a particular model of the gripping member.

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

[0089] According to a first embodiment of the method, all the steps "E3" of verifying the second gripping members 34B are carried out before the first step "E1" of transporting the second gripping members 34B, when all the second gripping members 34B are still stored in the storage magazine 52.

[0090] For example, each verification step "E3" is carried out successively for each second gripping member 34B by individual analysis of each second gripping member 34B. In this case, the robotic arm 46 passes the optical sensor device 60 in front of each second gripping member 34B. Step "E3" is therefore repeated until all the second members 34B have been analyzed, as indicated by condition "C1" of the.

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

[0092] By doing so, it is possible to perform all verification steps "E3" in masked time while the thermal conditioning unit 14 is operating in a production mode, as indicated by block "B1" of the. This makes it possible to shorten the time during which the thermal conditioning unit 14 is in maintenance mode.

[0093] Then, the transport and assembly steps "E1", "E2" are carried out for each second gripping member 34B until the last, as indicated by the condition "C2" of the.

[0094] Only the transport and assembly steps "E1, E2" are carried out while the manufacturing facility 10 is in maintenance mode, as indicated by block "B2" of the.

[0095] According to a second embodiment of the invention, each step "E3" of verifying a second gripping member 34B is carried out after a step "E2" of mounting the second gripping member 34B on the preceding mobile support 32. Thus, after the step "E2" of mounting a second gripping member 34B, the robotic arm 46 grips a second following gripping member 34B in the storage magazine 52 to transport it and then fix it on its mobile support 32 in the mounting zone 48.

[0096] In this case, each verification step "E3" is carried out by individual optical analysis of each second gripping member 34B.

[0097] Said individual optical analysis can be carried out when the second gripping member 34B is still arranged in the storage magazine 52, just before the handling head 54 of the robotic arm 46 grips it, as indicated in. Thus, the verification step "E3" is carried out before the second gripping member 34B is gripped by the robotic arm 46. This makes it possible to avoid having to replace the second gripping member 34B when it is non-compliant.

[0098] In the variant shown in , the optical analysis of the second gripping member 34B is carried out during the step "E1" of transporting said second gripping member 34B by the robotic arm 46. Thus, the verification step "E3" is carried out in masked time during the transport step "E1".

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

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

[0101] This makes it possible to track the usage time of each second gripping member 34B, in particular to anticipate maintenance operations on said second gripping member 34B.

Claims

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 member (34B) of gripping 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 onto the mobile support (32) stopped in the mounting zone (48) and devoid of gripping member;- at least one step (E3) of automatic verification of the conformity of said gripping member (34B) by optical analysis using a device (60) with an optical sensor;characterized in that each step (E3) of verification of a gripping member (34B) is carried out before the start of the step (E2) of mounting the following gripping member (34B) onto its associated mobile support (32).; 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). 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). Method according to the preceding claim, characterized in that all the verification steps (E3) are carried out in masked time while the thermal conditioning unit (14) operates in a production mode during which first gripping members (34A) already equipping the conveying device (22) continue to transport preforms (12) to heat them in the heating zone (18). 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). 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). Method according to claim 6, characterized in that the optical analysis of a gripping member (34B) is carried out during the step (E1) of transporting said gripping member (34B) by the robotic arm (46). 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. 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 (E1) when it is still arranged in the storage magazine (52). 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). 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. 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). 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 provided with an optical sensor device (60) allowing the implementation of the verification step (E3).

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