Laser marking device, installation and associated process

Abstract

Title: Laser Marking Device, Installation and Associated Method The present invention relates to a laser marking device (1) for containers (2), in particular thermoplastic bottles or flasks, of the type comprising at least one body (23), a shoulder (24) extending from said body (23) at one upper end thereof, a neck (21) extending from the shoulder (24), and a base (22) at the lower end of said body (23), said device (1) comprising at least: - a plurality of laser marking stations (3), each station (3) comprising along an optical path at least one laser marking optical head (30) equipped with a laser head unit (300) and an optical system (320) for focusing a laser beam (31) to generate a mark (310) at the level of at least one marking zone (20) of each container (2) to mark said zone (20), said optical head (30) being connected to said device (40) via an optical channel (600),- control means (4) connected to the marking stations (3) and comprising a laser processing device (40) and the power supply means (41) for the laser marking stations (3), - a carousel (5) with a vertical axis of rotation X driven in rotation by at least one motor relative to a frame (7) by means of a bearing means (70), said carousel (5) comprising at least: - a first platform (50), said first platform (50) supporting a plurality of retaining members (54) for positioning said container (2) along an axis substantially parallel to the vertical axis of rotation X of said carousel (5), - a shaft (53) supporting the plurality of marking stations (3) such that each optical system (320) is located opposite a container (2) held by a retaining member (54),device (1) characterized in that it comprises dynamic focusing means (330) for adjusting the focal point as a function of the distance between said optical system (320) and said at least one marking zone (20) of the container (2). The invention also relates to an installation and a method for marking containers (2). Figure for the abstract: Figure 1,

Description

Title of the invention: Laser marking device, installation and associated method

[0001] Technical Field: The invention relates to a marking device, a marking installation, and a laser marking method for containers. State of the art

[0002] It is known to include information and decorations on containers, especially plastic bottles. The information on a container might include, for example, the expiration date of the contents or the formula of the product inside. Decorations might include, for example, the manufacturer's logo.

[0003] It is well known to include this information and decorations on paper or plastic labels. The labels are affixed to the final container after the container forming stage, that is, when the containers are formed into their final shape.

[0004] However, labeling containers has many drawbacks. Indeed, manufacturing, printing, and affixing the labels to the containers represents a high cost, especially for large-scale container production. Furthermore, the label is susceptible to being torn off during container handling. The end user then loses access to certain important information, such as the expiration date. Finally, recycling plastic containers is complicated by the presence of labels and glue. Indeed, to promote recycling, it is best to ensure that containers, labels, and other components are collected separately according to their different materials. However, manually removing labels from containers for separate collection can be a tedious task. Therefore, label removal is one of the factors hindering successful recycling.

[0005] For the inscription of important information, methods of marking the container wall have already been proposed. For example, it is known to print certain important information directly onto the container wall using a special ink. However, this printing method is not satisfactory because, for hygiene reasons, the ink used for marking must dry almost instantly and must also remain on the surface of the wall without penetrating the inside of the container through migration. Therefore, the ink has a composition specific, which is very expensive to manufacture. Furthermore, the use of ink also complicates the recycling processes for plastic containers.

[0006] To circumvent these problems, a marking process involving engraving the container wall has also been proposed. The engraving is generally carried out using a carbon dioxide laser. Such a marking process is achieved by removing material from the container wall, notably through evaporation. As a result, the wall has a locally reduced thickness. However, in the interest of economy and environmental protection, efforts are being made to reduce the thickness of container walls. This makes it possible to produce containers using less plastic material than before. However, removing material from a very thin wall risks weakening it to the point of cracking the container under the slightest stress.

[0007] Other known laser marking devices have quality problems with respect to parts or substrates that are not flat and / or that have a variable focal length with respect to the optics, as is the case for a large majority of containers. In such a case, the markings on the substrate are blurry, vary in height or spacing and might otherwise be illegible, thus rendering the characters unsatisfactory to use.

[0008] Furthermore, depending on the nature or dimensions of the container, the quality of the marking becomes highly variable: the focal distance between the laser device and the wall of the container to be marked is not the same across the entire surface of the area to be marked. In particular, when the container wall is cylindrical, the resulting marking is of lower quality at the periphery of the area to be marked.

[0009] To solve these marking quality problems while remaining compatible with high-volume container production, the present invention proposes to provide a laser marking device that guarantees optimal marking position on the container while allowing containers to be marked at a rate compatible with the productivity levels required in the industrial sector.

[0010] The invention advantageously proposes a laser marking device comprising dynamic focusing means to ensure quality marking on a container, without having to adjust the mechanical position of the parts of the marking station.

[0011] Thus, the invention makes it possible to adapt to different container formats without having to adjust the mechanical position of the parts of the marking station or the position of the container.

[0012] Furthermore, by using dynamic focusing means, to adjust the The invention allows the text or patterns to be positioned in a marking area oriented indifferently, in the desired direction, without altering the quality of the marking.

[0013] The invention relates first to a laser marking device for containers, in particular bottles or flasks made of thermoplastic material, of the type comprising at least one body, a shoulder extending from said body at one upper end thereof, a neck extending from the shoulder, and a base at the lower end of said body, said device comprising at least: - a plurality of laser marking stations, each station comprising along an optical path at least one laser marking optical head equipped with a laser head unit and an optical system for focusing a laser beam to generate a mark at at least one marking area of ​​each container to mark said area, said optical head being connected to said device via an optical channel, - control means connected to the marking stations and including a laser processing device and the means for powering the laser marking stations, - a carousel with a vertical axis of rotation X, driven in rotation by at least one motor relative to a frame and via a rolling means, the carousel comprising at least: - a first platform, the first platform supporting a plurality of retaining devices for positioning said container along an axis substantially parallel to the vertical axis of rotation X of said carousel, and - a barrel supporting the plurality of marking stations such that each optical system is located opposite a container held by a retaining device.

[0014] The device is characterized in that it includes dynamic focusing means for adjusting the focal point as a function of the distance between said optical system and said at least one marking area of ​​the container.

[0015] In embodiments, the dynamic means are arranged in the optical path between the optical channel and the optical system, preferably between the laser head unit and said optical system.

[0016] In embodiments, on the optical path, the dynamic means include a motorized lens, for example aligned with the laser head unit along a linear axis.

[0017] According to one possible variant, on the optical path, the dynamic means include a shape-changing lens.

[0018] In some embodiments, the optical system consists of a system of 3D three-dimensional laser marking, including said dynamic focusing means which are in the form of a focusing module for each point to be marked in at least one marking area of ​​the container.

[0019] According to another possible variant, the optical head includes a sensor for measuring the distance between the optical output and at least one marking area of ​​the container.

[0020] In embodiments there, at least one optical head of each marking station is capable of moving the focal point of the laser beam in three directions, namely a vertical direction, a horizontal direction and a longitudinal direction with respect to at least one marking area of ​​said container.

[0021] In embodiments, each marking station comprises two optical heads, placed head to tail in each of said stations so that the optical systems of the two optical heads are superimposed in order to simultaneously mark a marking area located in the upper part of the container and an area located in the lower part of said container.

[0022] According to a final possible variant, each marking station includes a pulsed laser optical head with a wavelength between 800 and 2000 nanometers.

[0023] The invention also relates to an installation comprising: - a laser marking device as described above, - a container processing station located upstream of the marking device, the processing station supplying the device directly or indirectly by means of a transfer wheel at a loading point, - a transfer wheel at a discharge point to release the marked containers directly or indirectly to a downstream conveying means.

[0024] In some embodiments, the installation includes a system for inspecting marked containers.

[0025] The invention also relates to a marking method comprising at least the following steps: - a first step consisting of carrying out a treatment on said containers, preferably filling and capping said containers, - a second step consisting of rotating said containers, preferably filled and sealed, around a vertical axis around which laser marking stations are rotated, in a manner synchronized with said containers, - a step of adjusting the focal point of the laser marking stations, preferably according to the dimensions and / or shape of said containers, and - a third step consisting of marking said containers during rotation.

[0026] In some embodiments, the container marking process further comprises: - after the container processing step, preferably filling and capping, a step of loading the containers at a loading point, - following the marking step, an unloading step at the level of an unloading point of said containers, each station and each container being moved respectively around said vertical axis of rotation between said loading point of said containers and said unloading point of said containers marked at the level of at least one area called marking before starting a new cycle.

[0027] According to one possible variant, after the loading step and during the rotation step, said containers are moved vertically.

[0028] Finally, in some embodiments, the marking step is carried out by a pulsed laser in the near-infrared.

[0029] Brief description of the figures: The invention will be better understood from the description below, which is based on possible embodiments, explained in an illustrative and in no way limiting manner, with reference to the accompanying figures, in which: - [Fig.l] schematically represents a perspective view of the device; - [Fig.2] represents a vertical cross-sectional view of the device; - [Fig. 3] shows a detailed view of a marking station and a container; - [Fig. 4] schematically represents a detailed view of the retaining organs containers; - [Fig.5] schematically represents a side and detailed view of a station for applying a laser beam to a held container; - [Fig.6] schematically represents an embodiment in which the device includes two scan heads; - [Fig.7] schematically represents an embodiment in which the The device includes a motorized lens, - [Fig.8] schematically represents an embodiment in which the device includes a shape-changing lens, - [Fig.9] schematically represents an embodiment in which the The device includes a 3D three-dimensional laser marking system, - [Fig. 10] schematically represents a top view of the device according to the invention and in particular of the rotation of the plates; - [Fig. 1 1] schematically represents an installation with an inspection system - [Fig. 12] schematically represents an example of the implementation of the method according to the invention.

[0030] Detailed description: In the following description, elements having an identical structure or analogous functions will be designated by the same reference.

[0031] The invention relates firstly to a device 1 for laser marking of containers 2, represented schematically in [Fig.1]. In the context of the invention, container 2 is a bottle or flask. It is made of plastic. Preferably, the container is made of polyethylene terephthalate, hereinafter referred to as PET. Container 2 can therefore be rigid or semi-rigid. It is intended to contain a fluid, a liquid, powders, or granules, particularly of a food or cosmetic type. Container 2 can have any shape, symmetrical or asymmetrical. It can have a rounded cross-section, generally circular or ovoid, or a polygonal cross-section, particularly rectangular or square. Preferably, said containers 2 have a rounded cross-section, particularly a generally circular one.

[0032] The containers 2 have at least one body 23, a shoulder 24 extending from said body 23, and a base 22 at the end of said body 23. The body 23 of a container 2 includes a peripheral wall 25. The wall 25 of a container 2 may be cylindrical, rectangular, or of any other shape. In a normal orientation, the container 2 rests on its base 22, and the principal direction is vertical. The base 22 may be generally flat, petal-like, or otherwise shaped. Preferably, the containers 2 are obtained by forming from thermoplastic preforms. Such preforms are generally obtained by injection molding.

[0033] In the context of the invention, the container 2 has at least one marking area 20, located on its wall. There, at least one marking area 20 is intended to receive a mark 310, made by laser marking. The marking zone 20 can be oriented so that the mark 310 is parallel to the main direction of the container 2, or orthogonal, or have any possible orientation with respect to the wall 25 of the container 2 along its main direction.

[0034] The device 1 according to the invention comprises at least a plurality of laser marking stations 3. A laser marking station 3 includes along an optical path at least one optical head 30 which is connected to control means 4 of the station 3. The control means 4 include the laser processing device 40 and the power supply means 41 of the stations 3. The laser processing unit 40, or laser 40, includes an emission source of light, or pumping source and possibly an amplifying medium to emit laser light in the form of a laser beam 31. According to one possible embodiment, the optical head 30 includes the amplifying medium.

[0035] The optical head 30 is connected to the laser processing unit 40 by a network of optical fibers and electrical links, or optical channels 600. The optical channels 600 include at least one optical fiber that is an optical waveguide for the laser light emitted, for example, by the laser processing unit 40. According to one possible variant, the amplifying medium is incorporated into the 600 optical channel in the form of a doped optical fiber into which the emitted light is injected towards a 300 laser head unit. Station 3 controls the optical head 30 and the emission of the laser beam 31 from the control means 4.

[0036] Thus, the optical head 30 comprises a laser head unit 300 and an optical system 320, removably mounted on said laser head unit 300. Preferably, the laser head unit 300 emits a laser light beam 31 directed in a predetermined direction.

[0037] The optical system 320 includes at least one mirror for moving the laser beam 31 in a horizontal plane and / or in a vertical plane, and optionally a lens at the optical output 321 of the optical system 320, for focusing the beam of light in the plane and at the level of at least one marking zone 20, to generate a mark 310 at the level of said at least one zone 20. By optical path, we mean the path taken by the laser light from its emission from, for example, the laser processing device 40 to the optical output 321 of the optical system 320 in the form of a laser beam 31. In other words, at least one marking zone 20 corresponds to a treatment surface within which the laser beam 31 is applied in a horizontal and / or vertical direction. Depending on the type of mark 310 to be applied, the focal point of the laser beam 31 is not necessarily located directly on the wall of the container 2; that is to say, in a longitudinal direction relative to at least one marking zone 20 of said container 2, the focal point of the laser beam 31 may be located, in particular, above the wall, directly on the wall 25, at the level of the outer skin of the container 2, or inside said wall 25, for example at the level of the inner skin of said container 2, or even beyond, in a focusing zone 311.

[0038] In embodiments, the device 1 includes a fixed lens 334, said fixed lens being of the spherical type, flat field, or preferably of the F-theta type in order to maintain the dimension of the focal point relatively constant in the plane.

[0039] According to one possible variant, the laser head unit 300 and the optical system 320 are in one piece.

[0040] In embodiments, the control means 4 of the laser station 3 comprise a plurality of cooling units, not shown.

[0041] Within the framework of the invention, laser marking on at least one area 20 of a container 2 can be done in particular by local modification of the refractive index, and / or by local modification of the transmission index, and / or by local modification of the reflection index of the material of said container 2.

[0042] Each marking station 3 includes at least one optical head 30 which emits and focuses the laser beam 31. According to one possible variant, said at least one optical head 30 generates the optical beam 31.

[0043] Within the framework of the invention, the device 1 includes dynamic focusing means 330 for adjusting the focal point as a function of the distance between the optical system 320 and at least one marking area 20 of the container 2.

[0044] In embodiments, the optical head 30 includes means (not shown) controlled to move the emitted beam 31, for example by means of movable mirrors relative to the marking area 20 of a container 2, in the direction of the optical axis or perpendicular to it.

[0045] According to one possible variant, the optical head 30 includes dynamic means 330 controlled to move the focal point of the emitted beam 31, for example by means of movable lenses relative to the marking area 20 of a container 2, in the direction of the optical axis.

[0046] Indeed, depending on the format of the containers 2, that is to say according to their dimensions and / or their shape, the curvature of the wall 25, or according to the mark 310 to be generated on said at least one marking zone 20, the distance between the optical output 321 and the marking zone 20 varies. In addition, laser marking processes require very precise positioning of the optical focal point relative to the marking zone 20, in the focal zone 311, otherwise it will not be possible to generate the mark 310.

[0047] Advantageously, the fact that the device 1 includes dynamic focusing means 330 makes it possible to generate a mark 310 at the level of at least one marking zone 20 without having to adjust the mechanical position of the parts of the marking station 3.

[0048] The optical path is the path taken by the laser light from the output of the laser processing unit 40 to the optical output 321 in the form of a laser beam 31. The light therefore travels from the optical channel 600 to the optical output 321, passing through at least one laser marking optical head 30. Generally, the light laser passes through a laser head unit 300 then an optical system 320 along the optical path.

[0049] In preferred embodiments, the dynamic means 330 are arranged on the optical path between the laser head unit 300 and the optical system 320.

[0050] One embodiment is illustrated in [Fig. 7], in which the laser head unit 300 comprises the dynamic means 330 in the form of a motorized lens 331. The laser head unit 300 also comprises a beam expander 335 and two mirrors 333. In the illustrative example in [Fig.7], light is emitted from a laser processing unit 40, then travels through an optical channel 600 and into the laser head unit 300. The motorized lens 331 moves the focal point of the laser beam 31 along the optical axis, along a longitudinal axis relative to the marking zone 20. An enlargement schematically shows the movement of the lens 331 in [Fig. 7]. For this purpose, the lens 331 includes movable optical means that allow the focal point to be moved along a longitudinal axis relative to the laser beam 31. We can see in the example of [Fig.7] a cylindrical wall 25 of a container 2. The focal length DI varies according to the location of the focal point, in a focalization zone 311. Still in [Fig.7], an enlargement of the wall 25 shows that it is notably possible to move the focal point so that it is located longitudinally above the outer skin of the wall 25 or inside the container 2, after the inner skin of said wall 25, within the focalization zone 311. Without adjustment, the generated marking would be of poor quality in the center or at the edges of the marking zone 20. In other words, the mark 310 cannot then be of uniform quality over the entire surface of at least the marking zone 20.

[0051] In possible embodiments, and as shown in [Fig. 7] or 8, the dynamic means 330 are coupled to a fixed lens 334, for example of type F-Theta, disposed at the optical output 321 of the optical system 320. The combined use of dynamic means 330, for example in the form of a motorized lens 331, and a fixed lens is particularly advantageous because it allows adjustment of the focal point of the laser beam 31 without moving the optical head 30 or the container 2.

[0052] In embodiments, the dynamic means 330, for example in the form of a motorized lens 331, are aligned with the laser head unit 300 along a linear axis.

[0053] According to one possible variant, the dynamic means 330, for example in the form of a motorized lens 331, are arranged along an axis orthogonal or substantially orthogonal to the vertical axis of rotation X of the carousel 5.

[0054] According to another possible variant, the dynamic means 330, for example in the form of a motorized lens 331, are arranged along an axis parallel or substantially parallel to the vertical axis of rotation X of the carousel 5.

[0055] In embodiments, the dynamic means 330 include a shape-changing lens 332 on the optical path of the laser light. A shape-changing lens 332 allows the focus of the laser beam 31 to be adjusted without moving the entire laser station 3. For example, the curvature of the shape-changing lens 332 is adjusted by applying an electric current, which changes the focal length in a few milliseconds. Specifically, the curvature of said shape-changing lens 332 can be adjusted by applying an electric current.

[0056] An example of such an embodiment is illustrated in [Fig.8]. In this illustrative example, the shape-changing lens 332 is located between the laser head unit 300 and the optical system 320. Two mirrors 331 and a laser beam expander 335 are located on the optical path. In [Fig.8], an enlargement schematically shows the change in focus.

[0057] In some embodiments, the optical system 320 consists of a three-dimensional 3D laser marking system, including dynamic focusing means 330. In this case, the dynamic means 330 are in the form of a focusing module for each point 200 to be marked in at least one marking zone 20 of a container 2. An example of the implementation of such a device is illustrated in [Fig.9]. Each point 200, along a longitudinal axis relative to at least one marking zone 20, is then dynamically controlled by the focusing module as a function of the shape and dimensions of the container 2.

[0058] In other words, the use of a 3D three-dimensional marking system is particularly advantageous because it allows for complete coordination of the scanning of the laser beam's focal point 31, simultaneously horizontally, vertically, and longitudinally with respect to at least one marking zone 20. The focal point of the laser beam 31 then moves longitudinally relative to the marking zone 20, so as to adjust the focus. This ensures uniformity of the focal point on all points to be marked in the marking zone 20, regardless of the shape or orientation of this zone 20 with respect to the principal direction of the container 2.

[0059] In some embodiments, the optical head 30 includes a sensor 340 for measuring the distance between the optical system 320 and at least one marking area 20 of the container 2. This embodiment is very advantageous because, as it will described later, it allows real-time adjustment of the focus of the laser beam 31 focal point, and therefore to obtain a precise, very legible mark 310, and this on all points of the marking zone 20.

[0060] The control means 4 include an electronic unit 400 for controlling the movement of the laser beam 31. The unit 400 can be parameterized at will to modify the mark 310 to be inscribed; for example, it is a numerical control. The parameters to be modified concern, for example, the coordinates of the movement of the beam 31, the speed of movement of the beam 31, etc. The 310 mark can consist of characters, patterns, barcodes, etc. Typically the distance DI between the output of the beam 31 and the marking area 20 of the container 2 can vary, depending on the shape and / or dimensions of the container 2.

[0061] The laser beam 31 can trace the mark 310 indifferently in a vector mode, i.e. by continuous tracing, or in a matrix mode, i.e. by point-by-point tracing.

[0062] Preferably, the electronic unit 400 communicates with the dynamic means 330, in order to adjust the focal point of the laser beam 31 during the making of the mark 310 on at least one marking area.

[0063] In some embodiments, the optical head 30 comprises a pulsed laser unit 300. The unit 300 generates the laser beam 31 which is then scattered by the optical system 320. Preferably, the wavelength of the emitted laser is between 800 and 2000 nanometers (nm). In embodiments, and depending on the type of marking required, it may also be possible to select a laser emitting a beam of different wavelengths, for example of the Ytterbium, Erbium, Thulium type fiber laser, or of the Nd-YAG or Nd:YVO4 solid type. Depending on different possible configurations, the laser light is emitted in particular from device 40, and / or optical channel 600 or from laser unit 300. As a possible alternative, the Nd-YAG laser is configured to emit a laser beam 31 with a wavelength of 532 nm emitting in the visible range, more precisely in the color green.

[0064] According to yet another embodiment of the invention, the laser of the Nd-YAG marking station 3 is configured to emit a beam 31 at a wavelength in the near ultraviolet, for example 355 nm. Preferably, the wavelength of the emitted laser beam 31 is therefore between 1000 and 1100 nm, or between 1500 and 1600 nm, or between 1900 and 2000 nm, depending on the type of containers 2 to be marked and / or the type of mark 310 to be applied to the marking area 20 of a container 2.

[0065] It was observed that the wall marking areas 20 in “PET” of the container 2 Materials targeted by the laser beam 31 in the near-infrared range, with appropriate power and / or exposure time, undergo a phenomenon known as "foaming." Foaming involves melting the material and generating bubbles that expand, forming a ridge on the surface. These bubbles remain trapped during cooling. The material's strength is minimally affected. Furthermore, the legibility of the resulting mark 310 is significantly improved because the gas bubbles within the material diffusely reflect the light.

[0066] Preferably, the marking station 3 uses a laser with a pulsed operating mode to generate short pulses of a duration of less than 500ns (nanoseconds) and of peak power on the order of kW (kilowatt) to several tens of kW depending on the marking desired and focusing the beam in the vicinity of the wall of the container 2, at the level of the marking zone 20.

[0067] According to other, unrepresented embodiments of the invention, other types of lasers can be used within the scope of the present invention. As explained previously, the laser is selected and adjusted to allow marking of the thermoplastic material wall, either on the surface or in depth, without, however, engraving the wall.

[0068] The device 1 according to the invention is characterized in that it comprises a carousel 5 with a vertical axis of rotation X, said carousel 5 being driven in rotation by at least one motor relative to a frame 7. A schematic view of an example embodiment of the device 1 and the carousel 5 is visible in [Fig.1].

[0069] The rotation of the carousel 5 relative to the frame 7 is achieved by means of a rolling means 70.

[0070] In embodiments, the carousel 5 is supported by a rotating chassis 6, rotating around the vertical axis of rotation X, in the form of an orientation ring which includes the bearing means 70. The rolling means 70 can, for example, be made in the form of two rings that can be rotated relative to each other, each ring having a raceway, and the ring having furthermore a rotation device consisting of rolling elements or bodies (such as balls or ball bearings) interposed between the two raceways and a device for fixing the constituent elements of the ring to prevent their separation while allowing the relative rotation of the two rings. The carousel 5 can then be rotated around the vertical axis of rotation X by connecting one ring to the frame 7, with the carousel 5's chassis 6 supported by the other ring. Thus, the carousel 5 can rotate relative to the frame 7. The ring connected to the frame 7 is called the fixed ring, and the other ring is called the rotating ring.

[0071] In embodiments, the chassis 6 in the form of a slewing ring may include external teeth mounted on the rotating ring. In one possible variant, the rotating frame 6 is cup-shaped and mounted on the rotating ring, for example, through blind or through mounting holes, smooth or threaded. Various machine components, not shown, are attached to this cup, the assembly forming a carousel. As an illustration, on a machine of the applicant, the rotating mass equipped with the organs of device 1 (optical heads 30, control means 4, plate 50, 51, 52, shaft 53, etc.) can have a weight of around ten tonnes for a rotation speed of the carousel, and therefore of the rotating ring, of around thirty revolutions per minute. The rotating ring and therefore the carousel 5 are driven in rotation by a motor, generally not directly, but via gear and / or belt mechanisms.

[0072] In some embodiments, the rotating chassis 6 is in the form of a column.

[0073] The carousel 5 of the invention comprises at least one first platform 50, or platform. The axis of rotation of at least one platform 50 is coaxial with the axis of rotation of the carousel 5. The 50 plate can be of any shape, but is preferably circular. As seen in [Fig.2], the platform 50 supports a plurality of retaining members 54 to position a container 2 along an axis substantially parallel to the vertical axis of rotation X of the carousel 5. In other words, a container 2 is held by a retaining member 54 and is driven in rotation by the first platform 50 of the carousel 5.

[0074] As seen in [Fig. 1] or 2, the carousel 5 also includes a shaft 53.

[0075] The shaft 53 supports the plurality of marking stations 3 such that each optical system 320 is located opposite a container 2, itself held by a retaining member 54. Preferably, the diameter of the barrel 53 is less than the diameter of the first plate 50 in order to facilitate the implementation of device 1.

[0076] As schematically shown in [Fig. 10], the containers 2 and the optical heads 30 are both driven in rotation about a vertical axis of rotation X relative to the frame 7. The synchronized rotation of the marking stations 3 and the containers 2, and the vertical position of the container 2 opposite the optical system 320 of an optical head 30, is particularly advantageous. Indeed, the working distance D2 between the optical system 320 and the marking zone 20 of the container 2 is then constant or substantially constant: the containers 2 are immobilized during marking, as are the optical systems 320, and the resulting marking is of high quality.

[0077] The marking stations 3, the control means 4 and the containers 2 are therefore driven in rotation in a synchronized manner with respect to the frame 7. The carousel 5 also includes a rotating 60° rotary joint that supplies in electricity power sources 41. For this purpose, the rotary joint 60 includes a rotating electrical commutator, located at the head of said rotary joint 60, which is powered by a fixed electrical cable. Conventionally, the rotating electrical commutator has fixed or rotating tracks on which rotating or fixed fingers respectively bear elastically, the entire assembly being housed under a casing (not shown) which is fixed to the chassis 6 and held in place by an anti-torque structure integral with the frame 7. Preferably, the barrel 53 is hollow so as to accommodate the rotating joint 60 in this hollow central part.

[0078] Thus, the invention makes it possible to mark the containers 2 during their rotation, which is extremely advantageous. It is then possible to mark containers 2 at a high rate, on the order of 8,000 to 100,000 markings per hour.

[0079] In embodiments, at least one optical head 30 of each marking station 3 is capable of moving the laser beam 31 in a horizontal plane and / or in a vertical plane. Preferably, the laser beam 31 is emitted in a direction orthogonal or substantially orthogonal to the vertical axis of rotation X of the carousel 5. The vertical plane corresponds to the plane that passes through the vertical axis of rotation X of the carousel 5 and the horizontal plane corresponds to the plane perpendicular to the axis of rotation X of the carousel 5.

[0080] In some embodiments, the shaft 53 of the carousel 5 includes means for vertically moving each marking station 3 or each laser head 30, such that each of said stations 3 or laser heads 30 can move vertically along the shaft 53, for example by means of slides placed on the shaft 53 and an actuation means (not shown). This has the advantage of allowing the optical system 320 to be positioned opposite the marking zone 20 of a container 2. Indeed, the type of container 2, its dimensions, and its shape can change, and it is then necessary to adjust the relative vertical positioning of the optical systems 320 and the marking zones 20 so that the optical output 321 is located opposite at least one marking zone 20. This adjustment can be made, for example, automatically via an electronic control unit 400 included in the control means 4, by a mechanical cam adjusted by an operator or by means of an actuator, or manually by the operator.

[0081] According to another possible embodiment, the first platform 50 and / or each retaining member 54 includes means for vertically moving a container 2. This embodiment is preferred because it is simpler to implement. Similarly, the adjustment of the vertical position of the marking zone 20 of the container 2 can be done, for example, automatically via an electronic control unit 400, or again by a drug. This vertical positioning is preferably carried out before the marking of containers 2.

[0082] In some embodiments, the carousel 5 comprises a second platform 51. The second platform 51 is called the lower platform because it is located below the first platform 50, called the upper platform. The second platform 51 is driven in rotation synchronously with the first platform, relative to the frame 7. The second plate 51 then supports holding means 54 in the form of a plate 541, on which the bottom 22 of a container 2 rests. The container 2 is then held firmly in position from above, preferably by its neck 21, by a gripping means 540; and from below, more particularly by its bottom 22, which rests on said plate 541. This embodiment, visible in [Fig.4], is very advantageous because it ensures that the container 2 is held in position during its rotation and therefore during its marking. In addition, the 541 plate contributes to the centering and vertical positioning assistance of the container 2.

[0083] In embodiments, the carousel 5 includes a third platform 52, whose axis of rotation is coaxial with the axis of rotation of the first platform 50. The third platform 52 supports the control means 4 and is preferably, but not exclusively, located above the first platform 50. It is particularly advantageous to position the control means 4 on the upper part of a third platform 52 located in the upper part of the drum 53. Indeed, this allows a primitive of movement of the containers 2 to be smaller than that of the control means 4. Also, this helps to avoid possible leakage problems, in cases where the containers 2 are filled before marking.

[0084] Fig. 2 shows an embodiment in which the carousel 5 comprises a first platform 50, a second platform 51 and a third platform 52. The first platform 50 supports the vertically movable retaining means 540, while the second platform 51 supports a plate 541, also vertically movable. Preferably, only the plate 541 is vertically movable. Indeed, it is preferable to position the container 2 vertically by pushing it from its base 22. In other words, in a preferred embodiment, only the plate 541 is actuated, or motorized, to move the container 2 vertically, the retaining means 540 then performing so-called passive translations.

[0085] Two laser marking stations 3 can be seen, each comprising two optical systems 320.

[0086] Preferably, the third platform 52 is located in the upper part of the shaft 53 and supports the control means 4, and in particular the laser processing device 40 and the power supply means 41. We can also see the rotary joint 60 and optical channels 600 which electrically connect the different elements.

[0087] In the embodiment shown in [Fig.2], the different platforms are connected to the barrel 53. It is also possible to link together two or three platforms 50, 51, 52 in the form of a console to be assembled on a shaft 53 of a carousel 5. Thus, according to one possible variant, the first tray 50 and the second tray 51 and / or the third tray 53 are in one piece.

[0088] In embodiments, and as seen in particular in [Fig.3], each marking station 3 comprises two optical heads 30. The two optical systems 320 can be superimposed along an axis parallel to the rotation axis X of the carousel 5 in each station 3, in order to simultaneously mark a marking zone 20a located in the upper part of the container 2 and a zone 20b located in the lower part of said container 2, in its normal orientation, i.e. when it rests on its bottom 22. The two 320 optical systems can also be arranged head to tail, as seen in [Fig.3].

[0089] According to another possible embodiment, illustrated in [Fig. 6], the station 3 comprises two optical systems 320a, 320b angularly offset by an angle α about an axis orthogonal or substantially orthogonal to the vertical axis of rotation X of the carousel 5. The angle α is, for example, between 30 and 160 degrees. Each optical system 320a, 320b performs the marking respectively on an area 20a, 20b. Optionally, the areas 20a and 20b can be positioned at the same height along an axis parallel to the axis of rotation X of the carousel 5. This embodiment is particularly advantageous because it allows a mark 310 to be made over a larger part of the circumference of a container 2.

[0090] The invention further relates to a container marking installation 100 2, comprising a laser marking device 1 as described above.

[0091] The installation 100 also includes a container processing station 10 2 located upstream of the device 1. The processing station 10 supplies the device 1 directly or indirectly from the outlet of a transfer wheel 8, at the level of a loading point 80. Such a processing station 10 can be, for example, a filler, a capper, a blower, a labeler, or any other container processing station 2 on a packaging line.

[0092] Advantageously, the installation 100 allows a continuous supply of containers 2.

[0093] An installation 100 according to one possible embodiment is schematically represented in top view in [Fig. 11]. Containers 2 travel on a conveyor 102 from a processing station 10, for example, a filling and capping machine. The containers 2 are then transferred, preferably continuously, via an upstream transfer wheel 8, to a loading point 80, at the device 1 according to the invention. In particular, the containers 2 are gripped by retaining elements 54. The plurality of laser marking stations 3 can be seen around the entire periphery of the drum 53 of the carousel 5. According to the variant illustrated in [Fig. 11], the installation 100 also includes an intermediate wheel 800 between the upstream conveying means 102 and the transfer wheel 8.

[0094] The stations 3 are positioned opposite the held containers 2, such that the laser beam 31 can be directed towards a marking area 20 on the containers 2, preferably orthogonally or substantially orthogonally to the axis of rotation X of the carousel 5. The direction of rotation is schematically represented by a circular arrow, which does not define the direction of rotation of said carousel 5 within the scope of the invention. In other words, the carousel 5 can rotate about its vertical axis of rotation X in either direction.

[0095] During the rotation of the containers 2 in a manner synchronized with the rotation of the marking stations 3, the containers 2 are therefore marked, that is to say that a mark 310 is affixed to at least one marking area 20 by means of a laser beam 31 emitted and diffused by the marking stations 3.

[0096] Following the marking, and as shown in [Fig. 11], the marked containers 2 are transferred from an unloading point 90 via a downstream transfer wheel 9. The containers 2 are, for example, placed on a downstream conveyor 101.

[0097] Preferably, the unloading of the containers 2 by means of the downstream transfer wheel 9 is also continuous. In other words, the installation 100 allows continuous marking of the containers 2, with a continuous supply of containers 2 to the device 1 from a container processing station 10 until their unloading onto a downstream conveyor 101. In other words, preferably, the carousel 5 of device 1 is driven in continuous rotation. This is particularly advantageous because it allows the marking of containers 2 to be carried out at a sustained rate.

[0098] As seen in [Fig. 1 1], the installation 100 may also include, in some embodiments, an inspection system 11. Such an inspection system 11 comprises at least one camera and a control unit (not shown) for verifying whether the mark 310 is compliant. In case of non-compliance, the container 2 must be destroyed or at least discarded to prevent further processing. The installation 100 may include means 110 for ejecting a container 2 whose marking 310 is not compliant. For these control purposes, in some embodiments, the installation 100 includes a central control unit 12 allowing the entry of information concerning the type of container 2, the format, the type of mark 310 to be affixed, the location of the marking zones 20, 20a, 20b, etc. According to one possible variant, the central control unit 12 communicates with the electronic control unit 400 of the means 4. In some embodiments, the central control unit 12 comprises: - a database 120 in which are recorded control programs for the marking device 1 and possibly other container processing stations 2, said database 120 being recorded in a memory device or stored on an independent server, - a processor connected to the memory to apply the program instructions and - a communication interface connected to the processor for communication at least with the electronic unit 400 of the control means 4. According to one possible variant, the central control unit 12 includes a calculation unit enabling the generation of real-time instructions based on measurements taken by different sensors, for example a height measurement sensor of a container 2, or the sensor 340 measuring the distance between the optical output 321 and at least one marking zone 20 of the container 2.

[0099] In embodiments, the central control unit 12 transmits instructions to the dynamic means 330 via the electronic unit 400. The dynamic means can then adjust the focal point of the laser beam 31 in order to produce a high-quality, homogeneous mark 310 over the entire surface of at least one marking zone 20.

[0100] In embodiments, the central control unit 12 transmits information in the form of instructions to the control means 4 via the rotary joint 60. The information transmitted relates, for example, to at least one marking zone 20, the characteristics of the mark 310, the marking parameters, etc. The electronic control unit 400 acts as a slave controller controlled by the central unit 12, known as the master unit. The electronic control unit 400 is programmed to control device 1 for the complete execution of a marking cycle, and in particular to transmit the instructions necessary for the proper execution of the marking to the dynamic means 330.

[0101] The central control unit 12 can also allow setting the direction of rotation of the carousel 5, or its speed of rotation.

[0102] The master control unit can therefore be connected to other slave controllers, in order to optionally adjust the rotational speed of the transfer wheels 8, 9, or more means of transport 101 and 102.

[0103] The central control unit 12 can also be connected to an inspection system 11 to allow setting the level of conformity of the mark 310 of a container 2. Conformity can be for example the legibility, the positioning of the mark, etc. According to one possible variant, the inspection system 11 transmits information concerning the quality of the marking to the central control unit 12, which can then send instructions to the electronic unit 400 of the control means 4, for example aimed at correcting the height adjustment of the mark 310, the focusing achieved by the dynamic means 330, or any other parameter related to the marking.

[0104] Advantageously, the central control unit 12 includes various sensors, including speed sensors, or the sensor 340 for measuring the distance between the optical output 321 and at least one zone 20 to be marked, the information collected from which is stored in the database 120 or transmitted to a processing unit of the central control unit 12. For example, the database 120 of the central control unit 12 records the speed parameters of the transfer wheels 8, 9, of the carousel 5, and information concerning the formats of the containers 2 to be marked, for example their dimensions and / or shape.

[0105] In some embodiments, the central control unit 12 also transmits instructions to the electronic unit 400 in order to transmit instructions to the holding elements 54 and / or the marking stations 3 to configure the positioning of the containers 2 in relation to the optical systems 320. The central control unit 12 then allows to automatically manage the vertical movement of the containers 2 and / or the marking stations 3, in particular according to the format of the containers 2.

[0106] In embodiments, the central control unit 12 allows setting the mark 310 to be affixed to the zones 20, 20a, 20b of a container 2.

[0107] An operator can enter the various parameters at the level of a dedicated interface of the central control unit 12, or possibly remotely. For these purposes, the central control unit 12 may include a control screen for the installation 100 with a dedicated human-machine interface allowing the entry of information, for example the entry of the container format 2, the choice of the brand 310, etc.

[0108] The invention also relates to a method for marking containers 2 comprising at least the following steps: - a first step El consisting of carrying out a treatment on said containers 2, - a second step E2 consisting of rotating said containers 2 around a vertical axis around which laser marking stations 3 are rotated, in a manner synchronized with said containers 2, - a step E2' of adjusting the focal point of the laser marking stations 3, preferably according to the dimensions and / or shape of said containers 2, and - a third step E3 consisting of marking said containers 2 during rotation.

[0109] In some embodiments, the method is implemented by the device 1 of the invention as described above. Device 1 according to the invention is therefore capable of implementing the marking process of the invention.

[0110] Preferably, the first processing step El is a step of filling and capping the containers 2. Indeed, it has been found that the laser marking with the laser beam 31 is of better quality (in terms of readability in particular) when the container 2 is filled. Indeed, it is generally difficult to use laser systems to mark plastic containers, and particularly PET containers, because laser marking tends to degrade the container due to the high power required to mark containers at a high rate. This can, for example, lead to the formation of holes in the container wall. Advantageously, in some embodiments, the process consists of marking a container 2 filled, preferably with liquid. This allows the liquid to rapidly dissipate the heat from the transmitted laser beam 31 and prevents degradation of the wall of said container 2. The internal integrity of the container 2 in contact with the liquid is thus maintained, while it is possible to generate a strong contrast with high power to achieve a high marking rate and confine the marking to the external surface of the wall of said container 2. Preferably, containers 2 are therefore filled and sealed before being rotated for marking.

[0111] Figure 12 schematically shows the steps of a process according to an embodiment in which the containers 2 are filled and sealed during a step EL Then, according to one possible variant, the filled and sealed container 2 is transferred to the retaining organs 54, as seen in [Fig. 12], for example by a gripping means 540 by the neck and a plate 541.

[0112] The grasped containers 2 are then rotated, in a synchronized manner with marking stations 3. Preferably, the rotation step is carried out continuously, without interruption: the container 2 enters the path of the device 1 and is then grasped and rotated.

[0113] During step E3, and during their rotation, the containers 2 are marked.

[0114] The method according to the invention includes a focal point adjustment step E2'. For each point of the mark 310, the device 1 adjusts the focal point simultaneously with the positioning of the laser beam 31 by the optical system 320. This E2' focal point adjustment step can be done after the containers 2 have been loaded, during their rotation, prior to the marking being carried out, or during the marking being carried out, as will be described below.

[0115] In some embodiments, the characteristics of the container 2, for example its shape, dimensions, and the mark 310, are pre-registered in the database 120 of the central control unit 12. The electronic unit 400 then transmits instructions to the dynamic means 330, and the focal point of the laser beam 31 is adjusted for each point 200 of the mark 310 during the marking process. These embodiments are preferred in cases where at least one marking area 20 is located on a complex surface of the container 2.

[0116] In some embodiments, no data has been previously recorded. The sensor 340 then transmits the information to the central control unit 12, which, via a processing unit, transmits instructions to the electronic unit 400. In other words, the marking process then includes a preliminary step of measuring the distance between the optical output 321 and at least one marking zone 20.

[0117] It is also possible to adjust the focal point of the laser beam 31 only once, prior to the marking step E3, in cases where the mark 310 and / or the marking zone 20 is of a simple type.

[0118] In other words, the E2' step of adjusting the focal point of the laser beam 31 can be done before or simultaneously with the E3 marking step.

[0119] Finally, following step E3, the containers 2 are unloaded. Preferably, the containers 2 are unloaded while the carousel 5 is rotating, with the carousel 5 not stopping for this unloading step.

[0120] In some embodiments, the marking step E3 is performed during rotation through an angular sector of less than 360 degrees around the vertical axis. In other words, each container 2 makes approximately one circumvolution, more precisely less than one complete rotation.

[0121] In embodiments, and as schematically represented in [Fig. 11], the method comprises: - after the container processing step El 2, a container loading step El' at a loading point 80, - after the marking step E3, the process includes an unloading step E4 at an unloading point 90 of the containers 2, each station 3 and each container 2 being moved respectively around said vertical axis of rotation between said loading point 80 of said containers 2 and said unloading point 90 of said containers 2 marked at a zone 20 called the marking zone before to start a new cycle including at least stages E1 to E4.

[0122] Advantageously, after the loading step El' and / or before step E3, the containers 2 are moved vertically. According to a possible embodiment, the laser marking stations 3 are moved vertically during or after said loading step El'. Thus, in embodiments, the containers 2 are moved vertically after loading, in order to adjust the positioning of at least one marking zone 20 opposite the marking stations 3, and in particular opposite the optical output 321 of an optical system 320. Containers 2 are therefore moved from a vertical position - or initial height - to a vertical marking position.

[0123] Preferably, after the loading step El', the vertical movement step of the containers 2 takes place during the step E2, that is to say during the rotation of the containers 2. Preferably, the rotation step E2 around the X-axis is performed simultaneously with all the other steps of the process. Therefore, the rotation step E2 occurs concurrently with the various steps E1', E2', E3, and E4, with the rotation being continuous. In other words, advantageously, there is no interruption in the movement of container 2.

[0124] According to another variant, the vertical movement step of the containers 2 is carried out before step E2, i.e. before the rotation of the containers 2. Then, once the marking step E3 is completed, the containers 2 are again moved vertically back from said vertical position to said initial position so that said containers 2 can be unloaded.

[0125] Containers 2 and / or stations 3 can also be moved during their rotation, during the rotation step E2 and / or during the marking step E3.

[0126] In some embodiments, the marking step E3 is carried out by a pulsed laser in the near-infrared.

[0127] In some embodiments, the marking process includes an additional step, after the marking step E3, of inspecting the marked containers 2.

[0128] The marking process can be implemented in an installation 100 as described above.

[0129] Thus, the invention relates to a particularly efficient container marking device 1 for containers 2, which not only allows for high-quality marking but also at a high rate. It is therefore no longer necessary to stop the movement of the container 2 to be marked, which directly and favorably impacts the operating rate of the industrial line.

Claims

Claims

1. Device (1) for laser marking containers (2), in particular bottles or flasks made of thermoplastic material, of the type comprising at least one body (23), a shoulder (24) in the extension of said body (23) at an upper end thereof, a neck (21) in the extension of the shoulder (24), and a bottom (22) at the lower end of said body (23), said device (1) comprising at least: - a plurality of laser marking stations (3), each station (3) comprising along an optical path at least one laser marking optical head (30) equipped with a laser head unit (300) and an optical system (320) for focusing a laser beam (31) in order to generate a mark (310) at at least one marking area (20) of each container (2) for marking said area (20), said optical head (30) being connected to said apparatus (40) via an optical channel (600), - control means (4) connected to the marking stations (3) and comprising a laser processing apparatus (40) and the power supply means (41) of the laser marking stations (3), - a carousel (5) with a vertical axis of rotation X driven in rotation by at least one motor relative to a frame (7) via a rolling means (70), said carousel (5) comprising at least: - a first plate (50), said first plate (50) supporting a plurality of holding members (54) for positioning said container (2) along an axis substantially parallel to the vertical axis of rotation X of said carousel (5), - a barrel (53) supporting the plurality of marking stations (3) such that each optical system (320) is located opposite a container (2) held by a holding member (54), such that said marking stations (3), said control means (4) and said containers (2) are rotated in a synchronized manner relative to said frame (7), said containers (2) being marked during their rotation, device (1) characterized in that it comprises - dynamic focusing means (330) for adjusting the focal point as a function of the distance between said optical system (320) and said at least one marking zone (20) of the container (2).

2. Device (1) according to claim 1, characterized in that the dynamic means (330) are arranged in the optical path between the channel (600) optical and the optical system (320), preferably between the laser head unit (300) and said optical system (320).

3. Device (1) according to claim 2, characterized in that, on the optical path, the dynamic means (330) comprise a motorized lens (331), for example aligned with the laser head unit (300) along a linear axis.

4. Device (1) according to claim 1 or 2, characterized in that, on the optical path, the dynamic means (330) comprise a shape-changing lens (332).

5. Device (1) according to claim 1, characterized in that the optical system (320) consists of a 3D three-dimensional laser marking system, including said dynamic focusing means (330) which are in the form of a focusing module for each point (200) to be marked from there at least one marking zone (20) of the container (2).

6. 6. Device (1) according to any one of the preceding claims, characterized in that the optical head (30) comprises a sensor (340) for measuring the distance between the optical output (321) and at least one marking zone (20) of the container (2).

7. Device (1) according to any one of the preceding claims, characterized in that at least one optical head (30) of each marking station (3) is capable of moving the focal point of the laser beam (31) in three directions, namely a vertical direction, a horizontal direction and a longitudinal direction relative to the at least one marking zone (20) of said container (2).

8. Device (1) according to any one of the preceding claims, characterized in that each marking station (3) comprises two optical heads (30), placed head to tail in each of said stations (3) so that the optical systems (300) of the two optical heads (30) are superimposed in order to simultaneously mark a marking zone (20a) located in the upper part of the container (2) and a zone (20b) located in the lower part of said container (2).

9. Device (1) according to any one of the preceding claims, characterized in that each marking station (3) comprises a pulsed laser optical head (30) whose wavelength is between 800 and 2000 nanometers.

10. Installation (100) comprising: - a laser marking device (1) according to claims 1 to 9, - a treatment station (10) for containers (2) located upstream of said device (1), said treatment station (10) directly or indirectly supplying said device 1 by means of a transfer wheel (8) at a loading point (80), - a transfer wheel (9) at an unloading point (90) for releasing said marked containers (2) directly or indirectly at a downstream conveying means (101).

11. Installation (100) according to the preceding claim, characterized in that it comprises an inspection system (11) for the marked containers (2).

12. Method for marking containers (2) comprising at least the following steps: - a first step (El) consisting of carrying out a treatment on said container (2), preferably filling and capping said containers (2), - a second step (E2) consisting of rotating said containers (2), preferably filled and capped, around a vertical axis around which laser marking stations (3) are rotated, in a manner synchronized with said containers (2), - a step (E2') of adjusting the focal point of the laser marking stations (3) preferably as a function of the dimensions and / or the shape of said containers (2), and - a third step (E3) consisting of marking said containers (2) during rotation.

13. Method for marking containers (2) according to claim 12 further comprising: - after the step (El) of treating a container (2), preferably filling and capping, a step of loading (El') the containers (2) at a loading point (80), - following the marking step (E3), a step of unloading (E4) at an unloading point (90) of said containers (2), each station (3) and each container (2) being moved respectively around said vertical axis of rotation between said loading point (80) of said containers (2) and said unloading point (90) of said containers (2) marked at at least one so-called marking zone (20) before resuming a new cycle comprising at least steps (El) to (E4).

14. Method according to claim 12 or 13, characterized in that, after the loading step (El') and, during the rotation step (E2), said containers (2) are moved vertically.

15. Method according to any one of claims 12 to 14, characterized in that the marking step (E3) is carried out by a pulsed laser in the near infrared.

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