Angular indexing method for preforms

Abstract

The present invention relates to a method for angular indexing of a preform (12), the preform comprising a body (14) and a neck (16), the method comprising: a marking step (E2) of the neck (16) of the preform (12), consisting in producing at least one mark (87) on the neck (16) of the preform (12); a loading step (E1) of loading the preform (12) by a heating station (20), during which the preform (12) is transported along a heating path by a support member called a transposer (38), the support member allowing the preform (12) to rotate about its axis (X1), during which the body (14) of the preform is heated; characterized in that the marking step (E2) is carried out during the loading step (E1) when the preform (12) carried by the transposer (38) is moving on the heating path.

Description

Field of the Invention

[0001] The present invention relates to a method for angular indexing of a preform, the preform comprising a body and a neck, the method comprising:

[0002] - a marking step of marking on the neck of the preform, the marking step consisting in producing at least one mark on the neck of the preform;

[0003] - a loading step of loading the preform by a heating station, during which loading step the preform is transported along a heating path by a support member, called a turret, allowing the preform to rotate about the preform axis, and during which the preform body is heated.

[0004] The present invention also relates to a heating station for using such a method. Background Art

[0005] It is known to produce thermoplastic materials, in particular polyethylene terephthalate (PET) containers, by blowing a preform that has been previously heated. The preform has a neck that has been molded into its final shape and thus serves to remain unchanged during the container production process.

[0006] In many cases, the preforms are injection molded at a first location and blow molded into the final shape of the container at a second location on a dedicated manufacturing facility. This technique allows the blow molding operation to be carried out as close as possible to the bottling location, and the injection molding operation can be carried out at any location. In fact, it is relatively easy and inexpensive to transport the smaller-sized preforms, while transporting the blown containers has the drawback of low economic return due to the very large volume of the containers.

[0007] The mass production of such containers is carried out in a container manufacturing facility.

[0008] To allow the shaping of the preform body, the preform body is heated to a temperature above the glass transition temperature, thus allowing the body wall to be ductile and significantly reducing its elastic limit. Conversely, the neck is maintained at a temperature below the glass transition temperature so as not to deform. For this purpose, the manufacturing facility includes a heating station that allows the preform body to be heated to the temperature required for the shaping step.

[0009] Thereafter, the preform thus heated is then sent to a heating station of the manufacturing facility. The heating station is equipped with a plurality of blowing stations, each of which includes a mold and a nozzle for blowing or stretch-blowing. The large number of blowing stations allows for the manufacture of containers at a high rate, such as a rate greater than or equal to 50,000 bottles per hour. The blowing stations are carried, for example, by a turntable that rotates such that the preforms are blown one by one at a high rate during their movement between an introduction point corresponding to the introduction of the preform into the associated mold and a demolding point corresponding to the discharge of the molded container outside the mold.

[0010] The containers thus obtained are received at the outlet of their molds by the grippers of a transfer wheel in order to convey them in rows, for example by a conveyor belt, to another device. The next station is, for example, a container filling station or a container labeling station.

[0011] Sometimes it is necessary to change the angular orientation of the preform or the container during its movement.

[0012] This change in angular orientation is necessary, for example, when the container has at least one section that is not axisymmetric with respect to the neck axis.

[0013] To obtain such an axisymmetric container, by a process commonly known as "preferential heating", the preform is usually preferentially heated in some parts. Then, the preform is received in the mold with a fairly defined orientation around its main axis so that the heating profile of the body matches the cavity of the non-axisymmetric container to be obtained.

[0014] Furthermore, the non-axisymmetric container thus obtained should be placed in a downstream labeling device with a fairly defined orientation so that the label can be applied to the receiving surface of the non-axisymmetric container for this purpose.

[0015] This change in angular orientation is also necessary in other configurations, for example, on some containers, whether axisymmetric or not, intended to be equipped with a spray gun, and the spray gun should be correctly oriented with respect to the label on the container.

[0016] These stations themselves are usually equipped with container transfer devices such as turntables. The angular orientation of the container can be changed directly on these transfer devices and / or on the transfer devices between two stations.

[0017] To allow for the correct orientation of the preform and / or the container, it is known to equip the neck of the preform with a mark that allows for its angular orientation around the neck axis with respect to a support. Since the neck retains its shape during the production of the container, this mark can still be used to allow for the orientation of the finished container around its neck axis.

[0018] This marking allows the determination of the angular orientation of the preform or the container relative to its support, and may also allow the modification of the angular orientation of the preform or the support so as to bring this marking to a reference position defined relative to the support.

[0019] Such markings are generally produced during the injection molding of the preform. For example, the marking is a cut made in the neck collar, or even a lug made in a groove located above the collar. Thus, the preform is already equipped with its marking before being fed into the container manufacturing facility.

[0020] However, such a preform means that when the heating station loads the preform, a first indexing of the orientation of the preform is carried out so as to make the heating profile correspond to the marking already provided on the preform. Then, when the blowing station loads the preform, the orientation of the preform must be checked and corrected again so as to make the heating profile correspond exactly to the mold cavity.

[0021] However, when the preform is incorrectly loaded with angular indexing into the heating station, its heating profile no longer coincides with its marking. This error is reflected in the mold since the orientation of the preform in the mold is determined based on the marking of the preform. Summary of the Invention

[0022] The present invention relates to a method for angular indexing of a preform, the preform comprising a body and a neck, the method comprising:

[0023] - a marking step of marking the neck of the preform, the marking step consisting in producing at least one marking on the neck of the preform;

[0024] - a loading step of loading the preform by a heating station, during which loading step the preform is transported along a heating path by a support member, called a turntable, allowing the preform to rotate about the axis of the preform;

[0025] It is characterized in that the marking step is carried out during the loading step when the preform is carried by the turntable.

[0026] According to other features of the method according to the teachings of the invention, implemented alone or in combination:

[0027] - the body of the preform is heated during a heating phase included in the loading step;

[0028] - the heating path comprises at least one working section and at least one rest section, the body of the preform being directly exposed to heating radiation along the working section, while the body of the preform is not exposed to heating radiation along the rest section, and the marking step is carried out when the preform is located on the rest section.

[0029] - The marking step includes at least one marking generation operation, and the marking generation operation consists in exposing a defined angular region of the outer surface of the neck to a laser beam which is strong enough to locally mark the neck of the preform;

[0030] - The marking step includes at least one marking generation operation, and the marking generation operation consists in printing a mark on the outer surface of the neck with a marking substance such as ink;

[0031] - Interrupt the rotation of the preform about the preform axis during each marking operation;

[0032] - Perform the marking operation while the preform rotates about the preform axis;

[0033] - The marking step includes at least two marking generation operations for generating marks in two distinct angular regions of the neck;

[0034] - The method includes the step of placing the hot preform into the forming die after the end of the loading step of loading the preform by the heating station, and the preform is oriented in the angular reference position relative to the die by means of the marks generated during the marking step.

[0035] The invention also relates to a heating station using the method implemented according to the teachings of the invention, and the heating station includes:

[0036] - A transfer device for transferring the preform, and the transfer device includes a turret chain for moving the preform along a heating path;

[0037] - A heating member for heating the preform, and the heating member is arranged along at least one upstream first working section of the heating path, and at least one rest section of the heating path is not exposed to the heating member;

[0038] It is characterized in that the heating station includes at least one marking device arranged along the at least one rest section.

[0039] Other features of the heating station implemented according to the teachings of the invention:

[0040] - The marking device includes a laser emitter arranged to emit a laser beam towards the neck of the preform carried by the turret located on the at least one rest section;

[0041] - The marking device includes a print head arranged to print a mark on the neck of the preform carried by the turret located on the at least one rest section;

[0042] - The heating path includes a downstream second working section, and at least one rest section is interposed between the two working sections of the first working section and the second working section, and the at least one marking device is arranged along the rest section interposed between the two working sections;

[0043] - The heating path includes at least one rest section upstream of the first working section arranged upstream, and the at least one marking device is arranged along the rest section upstream of the first working section;

[0044] - The heating path includes at least one rest section downstream of the second working section arranged downstream, and the at least one marking device is arranged along the rest section downstream of the second working section. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Other features and advantages of the present invention will become apparent from the following detailed description read with reference to the accompanying drawings, in which:

[0046] Figure 1 is a top view schematically showing a manufacturing facility for manufacturing a container using a preform;

[0047] Figure 2 shows a Figure 1 contour diagram of a preform to be loaded into the manufacturing facility;

[0048] Figure 3 is a schematic enlarged detailed view of a heating station belonging to the Figure 1 manufacturing facility, which is adapted to implement the angular indexing method according to the present invention;

[0049] Figure 4 is a sectional view taken along section 4-4 of Figure 3 showing a part of the preform transfer chain passing through the heating station;

[0050] Figure 5 is a sectional view taken along section 5-5 of Figure 3 showing a preform being marked using a marking device made according to the first embodiment of the present invention;

[0051] Figure 6 is a view similar to Figure 5 showing a marking device made according to the second embodiment of the present invention;

[0052] Figure 7 is a sectional view taken along section 7-7 of Figure 5 showing a swivel crank pin engaged between two fingers of an orienting device;

[0053] Figure 8 is a perspective view showing the neck of a preform that has undergone four marking operations during the implementation of the method according to the present invention in the Figure 3 heating station;

[0054] Figure 9 is a block diagram showing the indexing and alignment method implemented according to the teachings of the present invention. Detailed implementation manners

[0055] In the following description, the same reference numerals will be used to indicate elements having the same structure or similar functions.

[0056] In the following description, the terms "upstream" and "downstream" will be used with reference to the moving direction of the preform along the manufacturing path.

[0057] Figure 1 FIG. schematically shows a manufacturing facility 10 for batch manufacturing of thermoplastic containers using a preform 12. The container is, non - restrictively, a bottle here. Here, the thermoplastic material is formed of polyethylene terephthalate, which will be indicated hereinafter by its acronym "PET".

[0058] Figure 2 An example of the preform 12 is shown. Such a preform 12 is made of a thermoplastic material, here made of polyethylene terephthalate (PET). The preform has Figure 2 a main axis "X1" shown vertically therein. The preform includes a body 14 having a closed axial end at the lower part. The body 14 leads to an open neck 16 through its opposite end at the upper part. The neck 16 has a tubular shape, and the main axis of the tubular shape defines the main axis "X1" of the preform 12. Figure 2 Figure 2 Figure 2 The body 14 generally has an axially symmetric shape of an elongated tube along the main axis "X1". The neck 16 of the preform further includes a radially protruding annular collar 18.

[0059] The neck 16, including the collar 18, is outwardly defined by an outer surface 17.

[0060] A part of the outer surface 17 of the neck 16 has a generally cylindrical shape. The outer surface usually includes plug - fixing means, such as threads or grooves for elastic fitting of a plug.

[0061]

[0062] Referring to Figure 1 , the manufacturing facility 10 includes a heating station 20 for heating the preform 12. As a non - restrictive example, the heating station 20 is formed by a tunnel in which heating members 22 that emit heating electromagnetic radiation, such as infrared radiation, are arranged, such as halogen lamps or laser emitters.

[0063] As will be explained in more detail below, a transfer device 24 for transferring the preform 12 is arranged to pass the preform sequentially along the heating members 22 from the entrance to the exit of the tunnel. The traveling direction of the hollow body is indicated by the Figure 1 arrow in.

[0064] When leaving the heating station 20, the body 14 of the preform 12 becomes malleable by being heated above the glass transition temperature, while the neck 16 remains at a temperature low enough to maintain its initial shape.

[0065] The manufacturing facility 10 also includes a forming station 26 for forming the preform 12 thus heated. Referring to the flow of the preform 12 in the manufacturing facility 10, the forming station 26 is arranged downstream of the heating station 20.

[0066] The forming station 26 here includes a turntable 28 carrying a plurality of forming tables 30. The turntable is mounted to be rotatable about a central axis "X2". Thus, before starting a new cycle again, each forming table 30 can move between a loading point 32 of the preform 12 in the form of a hot preform and an unloading point 34 of the preform 12 in the form of a finished container around the axis "X2" of the turntable 28. Each forming table 30 particularly includes a mold (not shown), and the mold is equipped with a cavity for molding the finished container.

[0067] Referring to Figure 3 , the heating station 20 is shown in more detail. The transfer device 24 allows the preform 12 to move in rows along a heating path 36, which is shown in bold in Figure 3 .

[0068] The transfer device 24 includes a chain 37 composed of support members hereinafter referred to as "transposers 38", and each transposer is adapted to individually support a preform 12.

[0069] As Figure 4 shown, such a transposer 38 generally includes a mandrin 40, and the mandrin is here fitted into the neck 16 of the preform 12. For example, the mandrin 40 is press-fitted into the neck 16 of the preform 12, and the preform is thus temporarily fixed to the mandrin 40 by friction. The necessary frictional force is provided, for example, by an elastomeric material ring (not shown), and the elastomeric material ring is arranged in a groove around the mandrin 40.

[0070] The mandrin 40 is fixed to the lower end of a shaft 42, and the axis of the shaft 42 is coaxial with the axis of the carried preform 12. The shaft 42 is received in a guide bearing 44 of a link 46 of the transfer device 24. More specifically, the shaft 42 is rotatably mounted in the guide bearing 44 about its main axis "X1". This rotation advantageously allows the entire body 14 of the preform 12 to be exposed to the heating radiation emitted by the heating member 22 in a controllable manner.

[0071] In addition, the shaft 42 is here mounted to be axially slidable relative to the link 46. The link 46 includes a lower sleeve 48, and the lower sleeve has an annular lower end face 50 hereinafter referred to as a "unloading surface 50". Thus, the shaft 42 is mounted to be able to move between a lower working position as shown on the Figure 4 left side and as shown on theFigure 4 It slides between the upper non-operating positions shown on the right side. In the lower operating position, the chuck 40 can be inserted into the neck 16 of the preform 12, while in the upper non-operating position, the chuck 40 retracts into the sleeve 48 above the unloading surface 50 to allow the chuck 40 to exit from the neck 16 of the preform, and the preform remains locked outside the sleeve 48 by abutting against the unloading surface 50.

[0072] Generally, the chuck 40 is controlled to its non-operating position by a cam device (not shown), and the chuck is pushed to its operating position by an elastic member 52 axially interposed between the chuck 40 and the link 46, here a spring.

[0073] The rotation of the chuck 40 about the main axis "X1" of the preform 12 is controlled here by a gear 54, which is arranged at the upper end of the shaft 42 above the link 46 here. The gear 54 is designed to cooperate with a rack 56, which is arranged on at least one section of the travel path of the preform 12 in the furnace.

[0074] In a variant (not shown) of the present invention, the rotation of the chuck 40 is controlled by a separate motor, which is mounted on the link 46. Then this rotation is controlled by an electronic control unit.

[0075] Each link 46 here carries a single turret 38. In a variant, one link can carry two turrets. The links 46 are mounted to be hinged to each other about a vertical axis "X1" by hinges 58 to form a chain. The links 46 are thus assembled to form a closed chain 37.

[0076] The chain 37 meshes around a first guide wheel 60 and a second guide wheel 62, and these two guide wheels are each rotatably mounted about vertical axes "X2, X3". At least one of the guide wheels 60, 62 is driven in a clockwise direction by a motor (not shown).

[0077] Each turret 38 here moves continuously, i.e., without interruption, along a closed loop. A complete revolution of the turret 38 along the closed loop will be referred to as a "cycle" hereinafter.

[0078] The Figure 1 A useful section indicated by a thick line in forms a processing path. Each turret 38 is designed to load a preform 12 along this processing path, and another empty section through which the turret 38 passes empty completes the loop.

[0079] On the useful section, each turret 38 conveys a preform from the loading point 64 of the preform 12 to the transfer point 66 where the preform 12 is transferred to the blowing station 26. The loading point 64 and the transfer point 66 are arranged on the periphery of the first guide wheel 60.

[0080] For example, using the notched wheel 68, the preform 12 is successively conveyed to the loading point 64. At the loading point 64, each chuck 40 engages in the neck 16 of the preform 12 conveyed by the notched wheel 68. The notched wheel 68 is equipped with a number of notches 69 on its periphery, each notch being intended to support a preform 12.

[0081] At the end of the processing path, the hot preform 12 is transferred to the transfer wheel 70, which is here equipped with clamps 72 intended to grip each preform by the neck 16 of each preform 12. The turret 38 is then controlled towards its non-operating position by the control fork 74, which is here carried by the first guide wheel 60. The first guide wheel 60 more particularly includes a plurality of fork-shaped members 74 on its periphery. The groove 76 of each turret 38 is intended to engage with the fork-shaped member 74 to control its sliding, as Figure 4 shown.

[0082] In the unloaded zone, the turret 38 moves unloaded from the transfer point 66 to the loading point 64. The unloaded zone is arranged on the section "B1" of the chain 37 meshing around the first guide wheel 60.

[0083] The heating path includes at least one working section and at least one rest section. Along the working section, the body 14 of the preform 12 is directly exposed to the heating radiation of the heating member 22, while along the rest section, the body 14 of the preform 12 is not exposed to the heating radiation of the heating member 22.

[0084] In the example shown in the figure, the heating station 20 includes an upstream working section "H1" and a downstream working section "H2", which are formed by two straight sections of the transmission chain 37 tensioned between two guide wheels 60, 62. The heating member 22 is arranged along these two working sections "H1, H2" so that the body 14 of the preform 12 passing through these working sections "H1, H2" is exposed to the heating radiation. When the preform 12 passes through the heating working sections "H1, H2", it is generally driven to rotate around its axis "X1" to allow the body 14 of the preform 12 to be heated over its entire circumference. For this purpose, each working section "H1, H2" includes an associated rack 56 for driving the turret 38 to rotate.

[0085] During the entire heating path, the orientation of each turret 38 is controlled. In the figure in particular Figure 4In the embodiment shown, each turret here includes a crankpin 78 that is eccentrically arranged relative to the axis of rotation "X1". The crankpin 78 is adapted to pass between a set 80 of two converging inclined planes arranged along the path of the turret 38, allowing the turret 38 to be correctly oriented at the start of the heating path. The crankpin 78 is thus automatically positioned upstream relative to the direction of movement of the turret 38. At the outlet of the set 80 of converging inclined planes, the gear 54 meshes directly with the rack 56 such that, as long as the gear 54 meshes with the rack 56, the orientation of the turret 38 can be easily deduced from its position along the heating path.

[0086] When the turret 38 reaches the second guide wheel 62, the crankpin 78 is received between two fingers 82 of the orienting device 84. The orienting device 84 further includes an electric motor 86 that allows the fingers 82 to rotate about the axis "X1" so as to be able to orient the turret 38 about its axis "X1", as Figure 5 and Figure 7 shown. Thus, the second guide wheel 62 includes a plurality of orienting devices 84 that are arranged peripherally so that each turret 38 is loaded between two racks 56 by an orienting device 84.

[0087] In a variant (not shown) of the invention, the rack and / or the orienting device can be replaced by a separate electric motor that is used to drive the rotation of the turret carried by each link.

[0088] A protective member (not shown) is provided to protect the neck 16 of the preform 12 from heating radiation so that the neck 16 is maintained at a temperature below the glass transition temperature.

[0089] The heating path here includes three rest segments along which the body 14 of the preform 12 is not exposed to the heating radiation emitted by the heating member 22. The first upstream rest segment "P1" is arranged between the loading point 64 and the upstream working segment "H1". The intermediate second rest segment "P2" is interposed between the upstream working segment "H1" and the downstream working segment "H2". The intermediate second rest segment "P2" more particularly has an arcuate shape since it extends over a segment of the chain 37 that meshes around the second guide wheel 62. The third downstream rest segment "P3" is arranged between the downstream end of the downstream working segment "H2" and the transfer point 66. No heating member is arranged along the rest segments here.

[0090] As is known, when the manufacturing facility 10 operates in the container production mode, each preform 12 undergoes a loading step "E1" of being loaded by the heating station 20.

[0091] The loading step "E1" starts when the transfer 38 loads the preform 12 at the loading point 64 and ends when the preform 12 is transferred to the transfer wheel 70 at the transfer point 66. Thus, during the entire loading step "E1", each preform 12 is conveyed along the heating path by the associated transfer 38. During this loading step "E1", as the preform 12 passes through the working sections "H1, H2" of the heating path, the body 14 of the preform 12 is heated.

[0092] The parameter settings of each heating member 22 can be controlled so as to heat more or less some parts of the body 14 of the preform 12. The adjustable parameters include, for example, the position of the heating member 22 relative to the heating path and / or the power of the radiation emitted by the heating member 22. For example, these parameters are automatically controlled by an electronic control unit. Thus, by simultaneously controlling the heating radiation power and the orientation of the transfer 38 at any point on the heating path, the body 14 of the preform 12 can be heated according to a so-called "preferred" heating profile, which then allows the finished container to have an axially symmetric shape during the forming operation.

[0093] As explained in the preamble, in some applications, it is necessary to orient the preform 12 and / or the finished container before processing. For example, the preform 12 heated according to the "preferred" heating profile should be oriented to conform to the shape of the cavity of the mold in the forming table 30. To this end, it is known to produce a mark 87 on the neck 16 of the preform 12, since no transformation occurs in the neck 16.

[0094] The present invention relates to a method of angular indexing, which includes a marking step "E2", the marking step consisting in producing at least one mark 87 on the neck 16 of the preform 12.

[0095] According to the teachings of the present invention, as Figure 9 shown, the marking step "E2" is carried out during the loading step "E1" when the preform 12 carried by the transfer 38 passes through the heating path. More specifically, the marking step "E2" starts after the loading step "E1" starts and ends before the loading step "E1" is completed. This method advantageously allows the preform to be loaded at the heating station 20 without worrying about the orientation of the preform.

[0096] The marking step "E2" is here achieved by a marking operation of the mark 87, which consists in exposing a defined angular region of the outer surface 17 of the neck 16 to a laser beam, the laser beam being strong enough to locally mark the neck 16 of the preform 12. Relative to the dimensions of the neck 16, the laser beam is focused on a very small part of the neck. The thermoplastic material exposed to the laser beam then causes a local visual mark 87 to appear by a change in the material structure.

[0097] To this end, the heating station 20 is equipped with at least one marking device 89. For example, the marking device 89 is arranged to be fixed relative to the ground and opposite to the heating path.

[0098] The marking device 89 here includes a laser emitter 88, which can emit a laser beam 90 in the direction of the neck 16 of the preform 12 carried by the turntable 38. The laser beam 90 is preferably emitted substantially orthogonally to the outer surface 17 of the neck 16.

[0099] In a variant, the heating station 20 includes a plurality of laser emitters 88 carried by the second guide wheel 62. Each laser emitter 88 is then associated with an orienting device 84.

[0100] As Figure 5 shown, the laser emitter 88 can directly emit the laser beam 90 towards the neck 16.

[0101] In a variant, as Figure 6 shown, the marking device 89 includes a mirror 92. The laser emitter 88 first emits the laser beam 90 towards the mirror 92, and then the mirror 92 reflects the laser beam 90 towards the neck 16. This thus allows the laser beam 90 to be easily moved, so that for example, by only adjusting the orientation of the mirror 92 by means of a motor 94 without changing the orientation of the laser emitter 88, a mark 87 with a desired shape can be obtained. This allows, for example, to obtain a mark 87 that forms a straight line parallel to the axis "X1" of the preform 12.

[0102] According to a variant (not shown) of the present invention, the marking step "E2" includes at least one marking generation operation, which consists in printing a mark on the outer surface of the neck with a marking substance such as ink. To this end, the marking device 89 is formed by a printing head, which is arranged to print a mark 87 on the neck 16 of the preform 12 carried by the turntable 38. Visible ink can be involved, or also invisible ink, which can be made visible by exposure to radiation of a determined wavelength such as ultraviolet radiation.

[0103] For example, the marking step "E2" is carried out when the preform 12 is located on the rest sections "P1, P2, P3" of the heating path. This allows on the one hand to have more space to arrange the marking device 89, and also to avoid subjecting the marking device 89 to excessive heating. To this end, the marking device 89 is arranged along one of the rest sections "P1, P2, P3".

[0104] Advantageously, in order to be able to freely control the orientation of the preform 12 during the marking operation, the marking device 89 is arranged along the second rest section "P2". Thus, the orientation of the preform 12 can be controlled by the orienting device 84, which is itself controlled by an electronic control unit (not shown).

[0105] However, when the orientation of the preform 12 can be controlled, for example, by a separate motor at the first rest section "P1" or the third rest section "P3", the marking operation can also be performed in the first rest section "P1" or the third rest section "P3". In this case, at least one marking device 89 is arranged along the first rest section "P1" and / or the third rest section "P3". The marking device 89 is automatically controlled by an electronic control unit so that when the preform 12 reaches the marking area "Z" opposite the marking device 89, an operation of generating a mark 87 is performed on the neck 16 of the preform 12.

[0106] Although the marking operation by the laser beam 90 or by the print head is very fast, the rotation of the preform 12 about its axis "X1" can be interrupted during this operation to allow for more precise marking of the preform 12. Conversely, the movement of the preform 12 along its heating path of course continues at a constant speed.

[0107] In a variant, the marking operation is performed while the preform 12 rotates about its axis "X1".

[0108] The marking step "E2" includes at least two mark generation operations for generating marks in at least two distinct angular regions of the neck 16. Generally, the number of mark generation operations included in the marking step "E2" is the same as the number of marks 87 required for marking the neck 16 of the preform 12.

[0109] In Figure 3 the example, the marking step "E2" includes four mark generation operations to cause the neck 16 of the preform to have four marks 87 when it reaches the transfer point 66, as Figure 8 shown.

[0110] Here, each mark generation operation is implemented by a relevant marking device 89, as Figure 3 shown. All the marking devices 89 are identical. These marking devices are distributed along the second rest section "P2".

[0111] To allow each mark 87 to be generated in a different angular sector of the neck 16, the turret 38 rotates about its axis "X1" by means of the relevant orientation device 84 of the second guide wheel 62 so that the neck 16 presents the required angular sector of its outer surface 17 when it reaches opposite each marking device 89. In Figure 7 the example, the turret 38 pivots here by an angle α equal to 90° between each marking device 89. Thus, at the end of the marking step "E2", the neck 16 has four marks 87 that are arranged at 90° to each other about the axis "X1".

[0112] The orientation of the transposition 38 and, accordingly, the orientation of the preform 12 carried by the transposition 38 are controlled throughout the heating path, so that the marking 87 is precisely positioned relative to the heating profile of the preform 12. Thus, compared with the marking process of the prior art, the risk of marking positioning error relative to the heating profile of the preform 12 is significantly reduced.

[0113] The preform 12 thus marked by means of the method according to the invention then continues its journey to the forming station 26.

[0114] At the end of the step "E1" of loading by the heating station 20, when the step "E3" of placing the hot preform 12 into the forming die, the preform 12 is oriented relative to the die in an angular reference position by means of the marking 87 made during the marking step "E2".

[0115] According to a non-limiting example, the preform 12 is oriented in the die by means of a rotating nozzle as described in document FR 2 764 544. The angular position of the preform 12 relative to the die can be precisely determined, for example, by means of a camera device that takes an image of the neck. The image can then be analyzed by image processing software, which will allow the precise determination of the rotation angle required to bring the preform 12 to its angular reference position relative to the die.

Claims

1. A method for angular indexing of a preform (12), the preform comprising a body (14) and a neck (16), the method for angular indexing of the preform comprising: - A marking step (E2) of marking on the neck (16) of the preform (12), during which at least one mark (87) is produced on the neck (16) of the preform (12); - A loading step (E1) of loading the preform (12) by a heating station (20), during which the preform (12) is transported along a heating path by a support member, the support member being called a turret (38), allowing the preform (12) to rotate about the preform axis (X1); It is characterized in that the marking step (E2) is carried out during the loading step (E1) when the preform (12) is carried by the turret (38).

2. The angular indexing method of the preform according to claim 1, characterized in that The heating path includes at least one working section (H1, H2) and at least one rest section (P1, P2, P3), the body (14) of the preform (12) is directly exposed to heating radiation along the working section, while the body (14) of the preform (12) is not exposed to heating radiation along the rest section, and the marking step (E2) is carried out when the preform (12) is located on the rest section (P1, P2, P3).

3. The method for angular indexing of a preform according to any one of the preceding claims, characterized in that, The marking step (E2) includes at least one mark (87) generating operation, during which a defined angular region of the outer surface (17) of the neck (16) is exposed to a laser beam (90), the laser beam being strong enough to locally mark the neck (16) of the preform (12).

4. The preform angular indexing method according to any one of claims 1 to 2, characterized in that, The marking step (E2) includes at least one mark (87) generating operation, during which a mark (87) is printed on the outer surface (17) of the neck (16) with a marking substance such as ink.

5. The preform angular indexing method according to claim 3, characterized in that, During each marking operation, the rotation of the preform (12) about the preform axis (X1) is interrupted.

6. The preform angular indexing method according to claim 4, characterized in that, During each marking operation, the rotation of the preform (12) about the preform axis (X1) is interrupted.

7. The method for angular indexing of the preform according to claim 3, characterized in that, The marking operation is carried out while the preform (12) is rotating about the preform axis (X1).

8. The preform angular indexing method according to claim 4, wherein The marking operation is carried out while the preform (12) is rotating about the preform axis (X1).

9. The preform angular indexing method according to claim 5, wherein, The marking step (E2) includes at least two mark generating operations for generating marks (87) in two distinct angular regions of the neck (16).

10. The method for angular indexing of the preform according to claim 6, wherein The marking step (E2) includes at least two mark generating operations for generating marks (87) in two distinct angular regions of the neck (16).

11. The preform angular indexing method according to claim 1, characterized in that, The method for angular indexing of the preform includes a step (E3) of placing the hot preform (12) into a forming die after the end of the loading step (E1) of loading the preform by the heating station (20), and the preform (12) is oriented in an angular reference position relative to the forming die by means of the marks (87) generated during the marking step (E2).

12. A heating station (20) for implementing the method for angular indexing of a preform according to any one of the above claims, the heating station (20) comprising: - A transfer device (24) for transferring a preform (12), the transfer device including a chain (37) composed of turrets (38) for moving the preform (12) along a heating path; - A heating member (22) for heating the preform (12), the heating member being arranged along at least one upstream first working section (H1) of the heating path, and at least one rest section (P1, P2, P3) of the heating path not being exposed to the heating member (22); It is characterized in that the heating station (20) includes at least one marking device (89), and the marking device is arranged along the at least one rest section (P1, P2, P3).

13. The heating station (20) according to claim 12, characterized in that, The marking device (89) includes a laser emitter (88), and the laser emitter is arranged to emit a laser beam (90) towards the neck (16) of the preform (12) carried by the turret (38) located on the at least one rest section (P1, P2, P3).

14. The heating station (20) according to claim 12, characterized in that, The marking device (89) includes a print head, and the print head is arranged to print a mark (87) on the neck (16) of the preform (12) carried by the turret (38) located on the at least one rest section (P1, P2, P3).

15. The heating station (20) according to any one of claims 12 to 14, characterized in that, The heating path includes a downstream second working section (H2), and at least one rest section (P2) is interposed between the two working sections of the first working section (H1) and the second working section (H2), and the at least one marking device (89) is arranged along the rest section (P2) interposed between the two working sections.

16. The heating station (20) according to claim 12, characterized in that, The heating path includes at least one rest section (P1) arranged upstream of the upstream first working section (H1), and the at least one marking device (89) is arranged along the rest section (P1) arranged upstream of the first working section.

17. The heating station (20) according to claim 12, characterized in that, The heating path includes at least one rest section (P3) arranged downstream of the downstream second working section (H2), and the at least one marking device (89) is arranged along the rest section (P3) arranged downstream of the second working section.

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