Laser scanning head for marking an article

Abstract

The invention relates to a laser scanning head for marking an article, said scanning head (9) being constituted at least by a housing (10) comprising a laser input window (11) able to receive a laser beam emitted by a laser source, at least one galvanometer mirror (12) mounted on the rotation shaft of an electric motor (13) driving the rotation of said galvanometer mirror (12), and an output window (14) through which a marking laser beam is emitted towards the article (1), said scanning head (9) being remarkable in that said housing (10) comprises two opposite output windows (14) and emission means of two marking laser beams from the laser beam emitted by the laser source and passing through the input window (11) and emitted through the output windows (14).

Description

Technical Field

[0001] This invention relates to the field of marking articles, such as containers, particularly bottles or jars manufactured by blow molding or stretch blow molding of preforms made of plastic materials such as polyethylene terephthalate (PET) and / or recycled polyethylene terephthalate (rPET), and more specifically, laser scanning heads for marking such articles. Background Technology

[0002] In the field of manufacturing PET material containers, such as bottles, it is well known that decorations are made on the containers to display information such as capacity, composition of the contents, expiration date, and / or, for example, the logo of the product manufacturer.

[0003] Typically, the information is displayed on paper or plastic labels, which are affixed to the final container after the container forming step or after the container filling step, that is, when the container is formed into its final shape.

[0004] However, container labeling has many drawbacks. In fact, the manufacture of labels, their printing, and their adhesion to containers represent high costs, especially for high-volume container production. Furthermore, labels are likely to be torn off during container handling, leaving the end user unable to access certain important information, such as the expiration date. Finally, the recycling of PET containers is complicated by the presence of labels and adhesives, which constitute impurities, making the containers opaque and altering the mechanical properties of containers obtained from recycled PET (rPET).

[0005] Methods for marking container walls have been proposed for recording important information. Therefore, it is known to directly print certain important information on the container wall using special inks.

[0006] However, this method of printing markings is not satisfactory because, for hygiene reasons, the ink used for marking must dry almost instantly, and it must remain on the surface of the wall without migrating into the container. Therefore, the ink has a special component that is very expensive to manufacture.

[0007] In addition, the use of ink complicates the recycling methods for plastic containers.

[0008] To overcome these problems, a marking method is proposed that involves etching the container wall. Etching is typically performed using a carbon dioxide laser. This marking method removes material from the container wall, particularly through evaporation. Consequently, the container wall exhibits a locally reduced thickness.

[0009] However, considering both economic and ecological factors, efforts are being made to reduce the thickness of container walls. This could potentially allow for the use of less plastic material in container construction. However, removing material from very thin walls carries the risk of making them brittle enough to cause the container to rupture under even the slightest stress.

[0010] Other known laser marking devices have quality issues with non-planar components or substrates and / or components with variable focal lengths relative to optics, which is the case for the vast majority of containers.

[0011] In this case, the markings on the substrate are blurry, vary in height or spacing, and may be difficult to read, thus making the characters unsatisfactory to use.

[0012] To overcome this problem, it is often necessary to stop the movement of the containers to be labeled, which directly affects the operating rate of the industrial production line.

[0013] In this regard, laser marking devices for thermoplastic containers, particularly bottles or vials, obtained by blow molding and stretching methods have been envisioned. This is particularly true of documents EP2380693, EP2983106, FR2907370, and CN116275544.

[0014] Document EP2380693 describes a marking system for moving objects, such as containers, using a laser. The system includes a laser system with a laser beam capable of marking within a working area and a modulator, a drive system capable of moving the object to be marked using a speed modulator, and a sensor system for obtaining the position of the object to be marked. The laser system and the sensor system are connected such that the modulator of the laser system has a signal input corresponding to a position signal from the sensor system. The laser system and the drive system are connected such that the speed modulator of the drive system receives a speed change signal from the laser system modulator, which is a function of the position signal received by the laser system relative to the working area and the position of the laser beam within the working area.

[0015] Document EP2983106 describes a method and system for printing information on containers. The method comprises providing a printing system with a laser source designed to generate a printing beam and direct the beam to several locations on a material, and / or adjusting the immersion time of the printing beam at at least one location to form a mark at each location. The method may also comprise a printing system designed to print a code on a product moving in one direction, and / or print the code based on a set of corrected data. The system includes a laser designed to generate a printing beam of up to 25 watts, and a housing including a printing beam output element through which the beam exits the housing. Finally, the system includes a set of optical components within the housing that allow the printing beam to be focused onto the product adjacent to the housing.

[0016] Document FR2907370 describes an apparatus for marking transparent or translucent objects at the exit of a forming machine, the objects continuously translating in front of a marking station comprising a laser beam generating device for ensuring the marking of the objects. The apparatus includes a position determining device for each object in at least one lateral direction of travel, these devices being positioned upstream of the marking station relative to the direction of travel; a moving device for the focusing plane of the laser beam in the lateral direction of travel; and a control device for the moving device connected to the determining device, allowing adjustment of the focusing plane of the laser beam according to the position of each object to be marked, thereby optimizing the marking of the objects by the laser beam.

[0017] Document CN116275544 describes a batch laser marking system for plastic bottles, comprising a first spiral conveyor, a first bottle clamping and conveying device, a first finished product conveying device, and a network of flying laser marking devices. The flying laser marking device network includes multiple flying laser marking devices, with laser marking stations arranged in front of the laser scanning head of each flying laser marking device. The first bottle clamping and conveying device clamps plastic bottle necks arranged at equal intervals and conveys the bottle necks to the corresponding laser marking stations in the flying laser marking device network. The flying laser marking device network performs laser marking and drawing on the equally spaced plastic bottles, and the first bottle clamping and conveying device clamps the laser-marked plastic bottles and conveys them to the first finished product conveying device for transfer to the next production station.

[0018] However, all of these laser marking devices on plastic containers have the disadvantage of not being able to mark containers at high rates, that is, rates greater than 4,000 bottles per hour. Summary of the Invention

[0019] One of the objectives of this invention is therefore to remedy all or part of these disadvantages by providing a laser scanning head for marking articles, particularly plastic containers, which has a simple and inexpensive design and allows information to be printed on the articles at a high rate.

[0020] Therefore, according to the present invention, a laser scanning head for marking articles is proposed, the laser scanning head comprising at least a housing including a laser input window capable of receiving a laser beam emitted by a laser source, at least one galvanometer mirror mounted on the rotation shaft of a motor driving the galvanometer mirror to rotate, and an output window through which the marking laser beam is emitted toward the article; notably, the laser scanning head is characterized in that the housing includes two opposing output windows and an emitting device for two marking laser beams that are emitted from the laser source, pass through the input window, and are emitted through the output window.

[0021] According to the first embodiment, the two-beam laser emitting device is capable of simultaneously emitting two marking laser beams through two output windows.

[0022] According to the second preferred embodiment, the two laser beam emitting device is capable of alternately emitting marking laser beams through the first output window and the second output window.

[0023] In a preferred embodiment, the housing of each laser scanning head is substantially parallelepiped, with one wall comprising an input window and the other two opposing walls each comprising an output window.

[0024] Furthermore, the input window is formed on the upper wall of the parallelepiped shell, and the output window is formed on two opposite side walls of the shell.

[0025] Each scanning head includes a first galvanometer mirror that extends opposite to the input window and is fixed to the output shaft of a first motor. The first galvanometer mirror is capable of reflecting a laser beam passing through the input window toward a second galvanometer mirror, referred to as a distributor, that extends opposite to the output window and is fixed to the output shaft of a second motor. The output shaft of the second motor is orthogonal to the output shaft of the first motor.

[0026] In an optional configuration, each scanning head includes a first galvanometer mirror that extends opposite to the input window and is fixed to the output shaft of a first motor. The first galvanometer mirror is capable of reflecting a laser beam passing through the input window toward a second galvanometer mirror, referred to as a distributor, which is fixed to the output shaft of a second motor. The output shaft of the second motor is orthogonal to the output shaft of the first motor. The second galvanometer mirror distributor alternately reflects the laser beam onto third and fourth galvanometer mirrors that extend opposite to the output window, respectively. The third and fourth galvanometer mirrors are fixed to the output shafts of the third and fourth motors, respectively.

[0027] In a preferred embodiment, the output shafts of the second, third, and fourth motors extend in parallel.

[0028] In addition, each output window is equipped with an optical lens. Attached Figure Description

[0029] Other advantages and features will become more apparent from the following description, given as non-limiting examples, of several embodiments of a laser scanning head for marking articles according to the invention, with reference to the accompanying drawings, wherein:

[0030] Figure 1 This is a top view schematic diagram of a marking device including a laser scanning head according to the present invention.

[0031] Figure 2 This is a top view of the marking device according to the invention in the second step of the marking method.

[0032] Figure 3 This is a top view of the marking device according to the invention in the third step of the marking method.

[0033] Figure 4 This is a top view of the marking device according to the invention in the fourth and final steps of the marking method.

[0034] Figure 5 This is a schematic diagram of a laser marking device according to the marking apparatus of the present invention.

[0035] Figure 6 yes Figure 5 The diagram shown is a perspective view of the laser scanning head according to the present invention with a guide wire.

[0036] Figure 7 This is a front view of the container, which specifically shows two laser-marked areas. Detailed Implementation

[0037] In the remainder of this description, elements with the same structure or similar function will be assigned the same number.

[0038] Reference Figure 1 The following describes a marking device for a thermoplastic container 1, particularly a bottle or vial, obtained by a blow-stretching method from a preform of, for example, polyethylene terephthalate (PET) and / or recycled polyethylene terephthalate (rPET) or similar plastic material. The container 1 includes, as referenced Figure 7At least one body 2, a shoulder 3 of an extension at the upper end of the body 2, a neck 4 of an extension of the shoulder 3, the neck receiving a bottle stopper, and a wall 5, the wall 5 including two of the aforementioned information areas 6.

[0039] In this particular example, the wall 5 includes two information areas; however, it is quite clear that the wall 5 of the container 1 may include only a single information area 6 or more than two information areas 6 without departing from the scope of the invention.

[0040] Moreover, there is no doubt that container 1 can be replaced by any other item without departing from the scope of the invention.

[0041] In addition, refer to Figure 1 The device includes at least two conveyors 7a and 7b, which enable the container 1 to circulate along two different loop paths on two different packaging lines from the inlet (E) to the outlet (S) of each conveyor 7a and 7b, and a plurality of laser marking devices 8, which are capable of adding information to at least one of the information areas 6 of the container 1, referred to as the laser marking area of ​​the container. Each marking device is positioned between the two conveyors 7a and 7b and is capable of alternately adding information to the laser marking area of ​​the container 1 of the first conveyor 7a and then to the laser marking area of ​​the container of the second conveyor 7b. Each conveyor 7a and 7b consists of a stepper motorized belt conveyor.

[0042] Obviously, belt conveyors 7a and 7b can be replaced by any other equivalent conveying device, such as a clamp conveyor that holds the container 1 at the neck or similar location, which is well known to those skilled in the art and does not depart from the scope of the invention.

[0043] The conveyors 7a and 7b each include a spacer for the containers 1 so that each container faces each laser marking device 8.

[0044] Furthermore, the two conveyors 7a and 7b are positioned parallel to each other, such that the circulation paths of the containers 1 on the conveyors 7a and 7b have the same circulation direction. The step distance of each belt conveyor 7a and 7b is substantially equal to the separation distance between the four containers 1 transported by the conveyors 7a and 7b. As will be described in detail later, the first belt conveyor 7a moves one step when the second belt conveyor 7b stops, and vice versa.

[0045] Advantageously, the conveyors 7a and 7b may include means for adjusting their position relative to the laser marking device 8 in order to present the container 1 at a desired focal length. In practice, when marking of containers of different diameters can be achieved on the same equipment, it may be necessary to adjust this focal length between each production run.

[0046] Furthermore, in this particular implementation example, the device includes four marking devices 8, each comprising a means of emitting laser radiation in two opposite directions. The marking devices 8 are positioned equidistantly from the two conveyors 7a and 7b, i.e., along a centerline parallel to the loop path of the conveyors 7a and 7b, which will be described in detail later. The marking devices 8 are positioned equidistantly from each other on the centerline, having substantially the same separation distance between the containers 1 transported by the conveyors 7a and 7b.

[0047] It will be noted that the device may include more or fewer than four marking devices 8 without departing from the scope of the invention; however, it should be noted that a high production rate can be achieved using only four marking devices 8.

[0048] Therefore, refer to Figure 1 The four containers 1 of the first conveyor 7a are positioned relative to the four marking devices 8 of the equipment, so that each laser marking device 8 applies a mark in one or more of the information areas 6 of each container 1 of the first conveyor 7a for a duration of about 3 seconds, and the marking laser beam of the marking device 8 is directed toward the first conveyor 7a.

[0049] Following this marking operation of container 1 on the first conveyor 7a, refer to Figure 2 The marking direction of the marking device 8 is changed so that the marking laser beam of the marking device 8 is oriented in the opposite direction, that is, towards the second conveyor 7b, on which the container 1 extends opposite to the marking device 8. The time required to change the marking direction of the marking device 8 is approximately 0.1 seconds.

[0050] Reference Figure 3 The four containers 1 of the second conveyor 7b are positioned relative to the four marking devices 8 of the equipment, so that each laser marking device 8 applies a mark in one or more of the aforementioned information areas 6 of each container 1 on the second conveyor 7b for a duration of approximately 3 seconds, with the marking laser beam of the marking device 8 oriented toward the second conveyor 7b. Simultaneously, the first conveyor 7a is actuated one step to transport the four marked containers 1 outside the marking area of ​​the marking device 8 and to position the four new containers 1 of the first conveyor 7a relative to the marking device 8.

[0051] Following this marking operation of container 1 on the second conveyor 7b, refer to Figure 4 The marking direction of the marking device 8 is changed so that the marking laser beam of the marking device 8 is directed in the opposite direction, that is, towards the first conveyor 7a, on which the container 1 extends opposite to the marking device 8. The time required to change the marking direction of the marking device 8 is also approximately 0.1 seconds.

[0052] During the movement of the marked container 1 on the second conveyor 7b by actuating the second conveyor 7b one step in the new cycle, refer to Figure 1 Therefore, the container 1 of the first conveyor 7a is marked by the marking device 8, and the duration of one cycle is about 6.2 seconds, so that the device according to the invention allows about 4,600 containers to be marked per hour.

[0053] According to the second embodiment, refer to Figure 5 Each marking device includes at least one laser source, which is not in Figure 5 The image shows a laser scanning head 9 consisting of a housing 10, on the upper surface of which is a laser input window 11 capable of receiving a laser beam emitted by a laser source, at least one first galvanometer mirror 12 mounted on the rotation shaft of a first motor 13 that drives the galvanometer mirror 12 to rotate, and two opposing output windows 14 through which laser beams are alternately emitted, indicating that the laser beams are emitted through the first output window 14 and the second output window 14.

[0054] The housing 10 of each laser scanning head 9 is substantially parallelepiped, with one wall, in this case the upper wall of the housing 10, comprising the input window 11, and the other two walls, in this case two opposing side walls, each comprising an output window 14. It will be noted that the output window 14 may include an optical lens, which is not in... Figure 5 It is shown in the middle.

[0055] In addition, each scanning head 9 includes a first galvanometer mirror 12 that extends relative to the input window 11 and is fixed to the output shaft of the first motor 13. The first galvanometer mirror 12 is capable of reflecting the laser beam passing through the input window 11 toward a second galvanometer mirror 15, which is referred to as a distributor and extends relative to the output window 14 and is fixed to the output shaft of the second motor 16. The output shaft of the second motor 16 is orthogonal to the output shaft of the substantially horizontally extending first motor 13.

[0056] According to the second embodiment, refer to Figure 6 Each scanning head 9, in the same manner as described above, includes at least one laser source, which is not in Figure 6 The image shows a laser scanning head 9 consisting of a housing 10, the housing 10 having a laser input window 11 on its upper surface capable of receiving a laser beam emitted by a laser source, at least one first galvanometer mirror 12 mounted on the rotation shaft of a first motor 13 that drives the galvanometer mirror 12 to rotate, and two opposing output windows 14, through which a laser beam is alternately emitted.

[0057] The housing 10 of each laser scanning head 9 is substantially parallelepiped, with one wall, in this case the upper wall of the housing 10, comprising the input window 11, and two other walls, in this case two opposing side walls, each comprising an output window 14. It will be noted that the output window 14 may include an optical lens, which is not in... Figure 5 It is shown in the middle.

[0058] Each scanning head 9 includes a first galvanometer mirror 12 extending opposite to the input window 11 and fixed to the output shaft of a first motor 13. The first galvanometer mirror 12 is capable of reflecting a laser beam passing through the input window 11 toward a second galvanometer mirror 15, referred to as a distributor, fixed to the output shaft of a second motor 16. The output shaft of the second motor 16 is orthogonal to the output shaft of the substantially horizontally extending first motor 13. The second galvanometer mirror 15 distributor alternately reflects the laser beam to a third galvanometer mirror 17 and a fourth galvanometer mirror 18 extending opposite to the output window 14, respectively. The third galvanometer mirror 17 and the fourth galvanometer mirror 18 are fixed to the output shafts of a third motor 19 and a fourth motor 20, respectively. The output shafts of the second motor 16, the third motor 19, and the fourth motor 20 extend parallel and perpendicularly, allowing the alternating emission of marker laser beams through the output window 14.

[0059] Undoubtedly, the combination of the galvanometer mirror and the motor described above can be replaced by any other two laser beam emitting devices capable of alternately or simultaneously emitting two marker laser beams through the two output windows 14 of the laser scanning head 9 according to the invention without departing from the scope of the invention.

[0060] Finally, it is clear that the examples given above are merely specific illustrations that do not limit the scope of application of the invention in any way.

Claims

1. A laser scanning head (9) for marking an article (1), the scanning head (9) comprising at least a housing (10) including a laser input window (11) capable of receiving a laser beam emitted by a laser source, at least one galvanometer mirror (12) mounted on a rotation shaft of a motor (13) driving the galvanometer mirror (12) to rotate, and an output window (14) through which the marking laser beam is emitted toward the article (1), characterized in that... The housing (10) includes two opposing output windows (14) and a transmitting device for two marked laser beams that are emitted from a laser source and pass through the input window (11) and are emitted through the output windows (14).

2. The laser scanning head (9) for marking articles according to claim 1, characterized in that... The two-beam laser emitting device can simultaneously emit two marking laser beams through two output windows (14).

3. The laser scanning head (9) for marking articles according to claim 1, characterized in that... The two laser beam emitting device is capable of alternately emitting marking laser beams through the first output window and the second output window (14).

4. The laser scanning head (9) for marking articles according to claim 3, characterized in that... The housing (10) of each laser scanning head is substantially parallelepiped, with one wall comprising an input window (11) and two other opposing walls comprising output windows (14).

5. The laser scanning head (9) for marking articles according to claim 4, characterized in that... An input window (11) is formed on the upper wall of a parallelepiped housing (10), and is further characterized in that an output window (14) is formed on two opposite side walls of the housing (10).

6. The laser scanning head (9) for marking articles according to any one of claims 3 to 5, characterized in that... Each scanning head (9) includes a first galvanometer mirror (12) that extends relative to the input window (11) and is fixed on the output shaft of a first motor (13). The first galvanometer mirror (12) is capable of reflecting a laser beam passing through the input window (11) toward a second galvanometer mirror (15) that is called a distributor and extends relative to the output window (14) and is fixed on the output shaft of a second motor (16). The output shaft of the second motor (16) is orthogonal to the output shaft of the first motor (13).

7. The laser scanning head (9) for marking articles according to any one of claims 3 to 5, characterized in that... Each scanning head (9) includes a first galvanometer mirror (12) extending opposite to the input window (11) and fixed on the output shaft of a first motor (13). The first galvanometer mirror (12) is capable of reflecting a laser beam passing through the input window (11) toward a second galvanometer mirror (15), referred to as a distributor, which is fixed on the output shaft of a second motor (16). The output shaft of the second motor (16) is orthogonal to the output shaft of the first motor (13). The second galvanometer mirror distributor (15) alternately reflects the laser beam onto a third galvanometer mirror (17) and a fourth galvanometer mirror (18) extending opposite to the output window (14), respectively. The third galvanometer mirror (17) and the fourth galvanometer mirror (18) are fixed on the output shafts of a third motor (19) and a fourth motor (20), respectively.

8. The laser scanning head (9) for marking articles according to claim 7, characterized in that... The output shafts of the second motor (16), the third motor (19), and the fourth motor (20) extend in parallel.

9. The laser scanning head (9) for marking articles according to any one of claims 1 to 8, characterized in that... Each output window (14) is equipped with an optical lens.

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