Apparatus for printing on glass, machine for printing on glass and method for printing on glass

Abstract

The invention relates to a device (1) for printing on glass (V), characterized in that it comprises: a holder (2) configured to receive a glass article (V); at least one six-axis robot (3); a printing tool (21) comprising at least one printhead (22); a speed sensor configured to detect a relative printing speed of the at least one print head (22) with respect to a surface (S) of the glass (V); distance maintenance means configured to maintain a constant distance between the at least one print head (22) and the surface (S) of the glass (V); and control means configured to control the movement of the robot (3), to adjust the speed of movement of the at least one print head (22) as a function of the relative printing speed, and to adjust the distance between the at least one print head (22) and the surface (S) of the glass (V).

Description

Technical Field

[0001] The present invention relates to the field of printing, and more particularly, to an apparatus for printing on glass, a machine for printing on glass, and a method for printing on glass. Background Art

[0002] Digital printing (also known as inkjet printing) is usually used to deposit coatings on flat glass articles in two dimensions. In this case, the glass is usually moved at a constant height on rollers or on a conveyor belt. The print head moves above the glass at a constant height at a distance between 0.5 and 3 mm from the glass, making it easy to maintain a constant distance between the print head and the glass. During printing, the glass and / or the print head moves along the X and Y axes at a constant speed. For reasons of saving cycle time, the coating is preferably deposited in a single pass, which means that the print head passes over each point on the glass only once, as opposed to multiple passes.

[0003] For applications such as digital printing on automotive glass (such as, for example, windshields), printing is performed on flat glass before any bending or laminating steps. Only after the printing process has been completed, at the end of the bending step, does the glass take on its final three-dimensional shape. For this purpose, the inks used are ceramic or enamel-based inks and must be able to withstand temperatures exceeding 600°C, which are encountered during the subsequent three-dimensional glass forming steps (bending, lamination). In addition, for certain applications, several ink curing steps are required, in particular in order to develop specific ink properties, such as anti-sticking.

[0004] The digital printing coating method can be applied to three-dimensional everyday objects made of glass or other materials. These objects are generally cylindrical, such as bottles, glasses, flasks, etc. These objects are then rotated along their axis of symmetry while the print head rolls over the object perpendicular to the axis of rotation.

[0005] Thus, from patent US10933626B1 a device for decorating the outer surface of an article containing a beverage using digital printing is known. The article to be decorated is cylindrical. The device allows the article to be decorated to rotate along its axis of symmetry at a selected speed. The turret-type device is equipped with a digital printing station and an ink drying station, which are arranged in a circular arc above the part to be printed. The turret-type device allows the desired station to be brought above the article to be printed, while the latter rotates around itself for digital printing.

[0006] Patent application US20130222498A1 describes a machine for depositing ceramic-type inks on flat glass by digital printing. The glass is placed horizontally on the machine table. A digital print head is attached to a ramp above the glass and moves over the glass to cover its entire surface. The machine is equipped with a system for drying the ink so that the glass can then be moved towards a firing oven for shaping. FR3009235A1 describes a system for orienting a series of print heads at different angles. In a first configuration, the four heads are parallel to each other, oriented in the same direction to print a flat surface. The invention then allows the four heads to be oriented each at a specific angle so as to orient them in an arc of a circle, allowing printing on the concave surface of a cylindrical object and adapting to its radius of curvature. The patent describes a system in which the print heads are tiltable, but with a limited number of positions and configurations.

[0007] PCT International Application Publication WO2013143659A1 describes a method for decorating a three-dimensional object by digital printing using a print head carried by a six-axis robot. The invention describes a step for scanning the surface to be printed, allowing a set of points to be generated that constitute the trajectory to be covered by the robot for digital printing, and a step for digital printing using the print head.

[0008] Patent application US2021300061A1 describes a process for decorating three-dimensional objects that allows digital printing on three-dimensional objects using a machine equipped with a six-axis robot. The robot transports the three-dimensional object in front of a fixed digital printing head.

[0009] When deposition is performed on a surface by digital printing, droplets are sprayed towards the surface to be printed. Since the size of the droplets is a few picoliters (pL), and in order to ensure a uniform deposition that respects the shape of the image to be printed, a constant distance between the surface to be printed and the print head must always be maintained, as well as a constant relative speed between the print head and the surface to be printed.

[0010] Moreover, in the case of windshields, the ink is printed on the flat glass before bending (only ceramic inks are used). The ink is only ceramic, not organic, since the glass is then formed in a bending furnace at temperatures exceeding 600°C, which limits the number of ink references that can be used. Furthermore, these inks must have anti-stick properties in the case of face 2 or face 3 applications, which further limits the range of inks that can be used. Before lamination, laminated glass consists of two glazings, each comprising two sides, which defines a four-side system: - Face 1 corresponds to the face that will be on the outside of the vehicle for an automotive glazing, - face 2 corresponds to the face diametrically opposite face 1 and situated on the same glass before lamination and in contact with the interlayer (for example PVB (polyvinyl butyral)), - Face 3 corresponds to the face in contact with the other side of the sandwich, and Face 4 corresponds to the face diametrically opposite face 3 and situated on the same glass before lamination, and is also the face that will be situated inside the vehicle, in direct contact with the vehicle's passengers.

[0011] Finally, a specific ink pre-curing step is required, which increases the energy consumption for each windshield manufactured and can create quality defects on the glazing.

[0012] Furthermore, examples of digital printing on three-dimensional (3D) objects (whether glass or not) are limited to objects with an axis of symmetry and a large radius of curvature, such as bottles, flasks, baseball bats, etc. In this case, during the printing phase, the object is rotated along this axis of symmetry. The print head moves above the rotating object parallel to its axis of rotation. This therefore ensures uniform speed for both the rotating object and the print head, and printing is performed on an almost flat surface. This configuration cannot be applied to large glass products such as skylights or windshields.

[0013] Finally, although commercially available six-axis robots operating in "workpiece carrying" mode guarantee high spatial precision, i.e. systematically passing the same points on a path or trajectory, they cannot guarantee temporal precision, i.e. passing at a strictly constant speed over the entire path. Very sudden and rapid fluctuations of + / -10% around the set speed have been observed. Therefore, in applications of the digital printing type in which the print head adapts the droplet ejection frequency to the set speed applied to the robot and not to the actual speed of the robot at any given moment, defects in the pattern printed with this method may be observed, with some drops ejected onto the glass too early and others too late due to speed variations. The result is dot placement defects, as well as areas with too much ink and areas with too little ink.

[0014] Therefore, there is a need for an apparatus, machine and method for printing on glass that allows precise and controlled printing, thereby ensuring uniform and durable deposition on articles of varying geometries.

[0015] Applicants therefore propose to meet these needs by using an apparatus, machine and method that implements a six-axis robot that allows the print head to be tilted according to an infinite number of positions and configurations, a device for measuring in real time the speed of the print head relative to the article to be decorated, and a device for maintaining the distance between the print head and the glass. Summary of the invention

[0016] The object of the present invention is therefore a device for printing on glass, characterized in that it comprises: a holder configured to receive a glass article on at least one surface of which printing is to be performed; at least one robot configured to move an arm along six axes, the arm having one end connected to the base and an opposite free end; a printing tool, the printing tool comprising at least one print head, the at least one print head being configured to be mounted on a free end of an arm of at least one robot; a speed sensor configured to detect a relative printing speed of at least one print head relative to at least one glass surface; a distance maintaining device configured to maintain a constant distance between at least one print head and at least one glass surface; A control device is configured to control the movement of at least one robot, adjust the movement speed of at least one print head according to the relative printing speed, and adjust the distance between at least one print head and at least one glass surface by a distance maintaining device.

[0017] Thus, this type of device can detect the relative speed of at least one print head relative to the glass surface together and in real time and maintain a constant distance between at least one print head and the glass surface. Printing can be reliably reproduced even if there are differences in shape (curve) and thickness between two glass products.

[0018] Furthermore, real-time detection of the relative speed of at least one print head with respect to the glass surface allows a print head movement speed of at least 200 mm / s, and the combination of relative speed detection and distance maintenance results in very short cycle times to reduce printing times, which is particularly advantageous in the field of automotive glass production (20 to 40 seconds per piece of glass).

[0019] In addition, the velocity sensor compensates for the lack of temporal precision of the six-axis robot during the first realization of each trajectory by measuring in real time the instantaneous relative velocity of at least one print head with respect to the glass. This measurement is then transmitted to at least one print head, which adjusts its droplet ejection frequency in real time according to its position above the glass. This improves droplet deposition accuracy and reduces printing defects.

[0020] The apparatus for printing on glass according to the present invention allows the glass to remain stationary during printing, with at least one print head being movable and moving over the glass.

[0021] The device for printing on glass according to the invention allows the ink to be printed after the glass forming step. The use of a six-axis robot allows the print head to be tilted according to an infinite number of positions and configurations. The device for printing on glass according to the invention is therefore particularly suitable for printing on objects with various geometries and therefore allows the creation of decorations on glass, such as on windshields or sunroofs, or when the entire surface is to be decorated.

[0022] Furthermore, since the three-dimensional glass forming step can be performed after printing, there are fewer restrictions on the inks and therefore more inks can be selected.

[0023] In one embodiment, at least one of the print heads is a fast load and unload print head, such as pneumatic or magnetic. For example, The robotic tool changer thus allows for a rapid tool change on the robot.

[0024] Thus, different ink references can be printed consecutively with a minimum loss of time.

[0025] According to one embodiment, the distance maintaining means is at least one of: a system for constraining the glass according to a predetermined shape, preferably by suction cups, a system for scanning the glass surface to record its shape and a distance sensor carried by the printing tool.

[0026] According to one embodiment, the control device is composed of at least one of the following: a microcontroller, a processor, a microprocessor, a digital signal processor (DSP), a field programmable gate array (FPGA), an application specific component (ASIC), a computer, which includes software configured to control the robot, the printing tool and the distance maintaining device.

[0027] According to one embodiment, at least one robot is configured to move at least one print head in an adjacent swath scanning pattern, preferably continuously in two different directions over two adjacent swaths to reduce printing time. The result is thus continuous printing without unnecessary movement of at least one print head.

[0028] According to one embodiment, an apparatus for printing on glass includes a single robot and a gantry, the robot being attached to the gantry by its base such that the base is arranged above a holder.

[0029] According to one embodiment, the apparatus for printing on glass comprises two robots, wherein the robot bases are preferably arranged at the same height as the holder and on both sides of the holder.

[0030] According to one embodiment, each robot prints on half of at least one surface of the glass.

[0031] According to one embodiment, the device for printing on glass further comprises at least one additional print head and means for replacing at least one print head, which are configured to replace at least one print head with at least one additional print head, preferably by pneumatic or magnetic loading and unloading.

[0032] Thus, the replacement device allows printing different colors or inks on the same glass article using a single device for printing on glass, and also allows ink A to be printed on type A' glass and ink B to be printed on type B' glass. Finally, in the event of maintenance on a print head, one print head remains operational, thereby ensuring continuous and uninterrupted operation of the machine.

[0033] Another object of the invention is a machine for printing on glass, characterized in that it comprises, arranged in sequence: Glass loading station; Glass washing station; Optional glass scanning station; Glass surface preparation station; a printing station equipped with a device for printing on glass as described above; Drying station; Control station; unloading station; and Two adjacent stations are connected by a glass conveying device, preferably rollers or a conveyor belt.

[0034] Thus, the use of several modular stations allows the machine to run in sequence and process several glass articles at once. The configuration of the printing station is modular, as it can be equipped with several robots to reduce the cycle time.

[0035] According to one embodiment, the machine also comprises a post-processing station between the drying station and the control station.

[0036] Another object of the invention is a method for printing on glass implementing the device for printing on glass as described above, characterized in that the method comprises: loading the holder with a glass article, at least one surface of the glass article being printed on; Printing on the surface of glass products; Unloading the printed glass product. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to better illustrate the purpose of the present invention, several embodiments are described below in an illustrative and non-limiting manner with reference to the accompanying drawings.

[0038] In these graphs: Figure 1 is a perspective view of an apparatus for printing on glass according to a first embodiment of the present invention; Figure 2 is based on Figure 1 A schematic diagram of an apparatus for printing on glass; Figure 3 is a top view of glass printed by the apparatus for printing on glass of the present invention according to a scan pattern; Figure 4 is a perspective view of an apparatus for printing on glass according to a second embodiment of the present invention; and Figure 5 is a schematic diagram of a machine for printing on glass according to the present invention. DETAILED DESCRIPTION

[0039] Reference Figure 1 , it can be seen that it shows a device 1 for printing on glass according to a first embodiment of the present invention.

[0040] The device 1 for printing on glass comprises a holder 2. The holder 2 may be any holder known to a person skilled in the art for printing, suitable for receiving an object on which printing is to be performed. The holder 2 may be fixed. In this case, an operating tool will load the glass V on which printing is to be performed onto the holder 2. The holder 2 may be movable, such as, for example, arranged on a conveyor.

[0041] The device 1 for printing on glass also includes a robot 3. The robot 3 is a six-axis robot. Figure 1 As can be seen in the figure, and as is well known to those skilled in the art, the robot 3 comprises a base 4 and an articulated arm 5.

[0042] The base 4 has a flat mounting surface 6 , and the base 4 can be mounted on the external frame through the flat mounting surface 6 .

[0043] The arm 5 comprises a proximal end 7 connected to the base 4 and a free distal end 8 opposite the proximal end 7. The proximal end 7 of the arm 5 is connected to the base 4 via a shoulder 9. The shoulder 9 is rotatable relative to the base 4 along a first axis 10 perpendicular to the mounting surface 6.

[0044] The arm 5 comprises an upper arm 11. The upper arm 11 is pivotally connected to the shoulder 9 along a second axis 12 perpendicular to the first axis 10.

[0045] The arm 5 comprises an elbow 13. The elbow 13 is pivotally connected to the upper arm 11 along a third axis 14 parallel to the second axis 12.

[0046] The arm 5 comprises a forearm 15 . The forearm 15 is rotatable relative to the elbow 13 along a fourth axis 16 which is perpendicular to the third axis 14 and extends in the longitudinal direction of the forearm 15 .

[0047] The arm 5 comprises a first wrist 17. The first wrist 17 is pivotally connected to the forearm 15 along a fifth axis 18 parallel to the third axis 14.

[0048] The arm 5 comprises a second wrist 19 at the distal end 8 of the arm 5. The second wrist 19 is rotatably connected to the first wrist 17 along a sixth axis 20 perpendicular to the fifth axis 18.

[0049] Therefore, the robot 3 is configured to move the arm 5 along six axes.

[0050] The device 1 for printing on glass further comprises a printing tool 21 .

[0051] exist Figure 1 In the figure, it can be seen that the printing tool 21 comprises a print head 22, which is mounted at the distal end 8 of the arm 5, on the second wrist 19. It goes without saying that a person skilled in the art will be able to choose any print head suitable for the printing requirements to be performed, such as for example the number and type of nozzles and their arrangement.

[0052] It should also be noted that a person skilled in the art is equally capable of selecting any printing tool suitable for the printing needs to be performed (in particular any necessary configurations and equipment, such as, for example, feed tubes, ink tanks and a 24-hour ink recirculation system, which remain fixed). These will not be described in detail herein.

[0053] according to Figure 1 In the first embodiment shown in FIG. 2 , the robot 3 is located above the holder 2. To this end, the robot 3 is mounted on the gantry 23 so that the mounting plane 6 is parallel to the holder 2. Preferably, the device 1 for printing on glass is configured so that during printing, the center of the base 4 is perpendicular to the center of the surface S of the glass V on which printing is to be performed. During printing, the arm 5 of the robot 3 is extended towards the glass V below.

[0054] It should be noted that the device 1 for printing on glass according to the invention is suitable for printing on several surfaces of the same glass article, for example printing on both sides of a windshield.

[0055] Under each print head 22, a low-power UV lamp can be found, intended to freeze the ink drops without completely drying them, to avoid dripping before the entire surface S of the glass V has been printed. This UV lamp must be correctly oriented to avoid any reflection of UV rays towards the print head 22, which would cause polymerization of the ink on the surface of the print head 22. It is also possible to envisage the use of a similar IR fixing system for IR inks or a hot air fixing system for thermal inks.

[0056] As from Figure 2As can be seen in the schematic diagram in , the device 1 for printing on glass comprises a speed sensor 24 configured to detect the relative printing speed of the print head 22 with respect to the surface S of the glass V on which printing is to be performed.

[0057] Preferably, the speed sensor 24 is located near the print head 22, or even directly on the print head.

[0058] The device 1 for printing on glass further comprises a distance maintaining device 25 configured to maintain a constant distance between the print head 22 and the surface S of the glass V on which printing is to be performed.

[0059] The distance maintaining means 25 is at least one of: a system for constraining the glass according to a predetermined shape, preferably by means of suction cups, a system for scanning the glass surface to record its shape, and a distance sensor carried by the printing tool 21 .

[0060] Thus, for example, in a first variant of the glass restraint system, a frame equipped with suction cups can restrain the glass article very accurately according to a predetermined shape, and the movement of at least one printing head is preprogrammed on this basis.

[0061] According to a second variant, each glass object is scanned by a shape detection tool (laser scanning, camera with image processing software) in order to precisely determine the shape of each glass object and to adjust the path of at least one printing head accordingly.

[0062] According to a third variant, the distance between at least one print head and the glass surface can be calculated in real time by a distance sensor carried by a robot, at least one print head or other device (a camera with image processing software) to adjust the path of at least one print head accordingly to always maintain a predetermined distance between the two elements.

[0063] The apparatus 1 for printing on glass further comprises a control device 26. The control device 26 is connected to the robot 3, the print head 22, the speed sensor 24 and the distance maintaining device 25. The control device 26 is configured to control the movement of the robot 3, adjust the movement speed of the print head 22 according to the relative printing speed detected by the speed sensor 24, and adjust the distance between the print head 22 and the surface S of the glass V on which printing is to be performed through the distance maintaining device 25. The control device 26 is also configured to control printing according to a predefined scanning pattern.

[0064] The control device 26 is composed of at least one of the following: a microcontroller, a processor, a microprocessor, a digital signal processor (DSP), a field programmable gate array (FPGA), an application specific component (ASIC), a computer, and includes software configured to control the robot 3, the printing tool 21 and the distance maintaining device 25.

[0065] exist Figure 2 , it can be seen that the printing device 1 can additionally and optionally include an additional print head 27. The additional print head 27 is a spare head for the same or different ink (e.g. different color or different structure, property or composition). Advantageously, the additional print head 27 can be stored on a storage rack. Advantageously, the print heads 22, 27 are of the fast loading and unloading type, such as pneumatic or magnetic type.

[0066] In this case, the device 1 for printing on glass is equipped with means 28 for replacing the print head, configured to replace the print head 22 mounted at the distal end 8 of the arm 5 with an additional print head 27. The means 28 for replacing the print head are of a type well known to those skilled in the art, preferably by pneumatic or magnetic loading and unloading.

[0067] Replaced print heads 22 can be placed on the storage rack.

[0068] It should be noted that a person skilled in the art will be able to determine the number of additional print heads required for the printing operation to be performed, as well as the number and nature of the devices 28 for replacing the print heads.

[0069] During the printing phase, the glass V is stationary; all movements are performed by the robot 3. The trajectory of the robot 3 is adjusted according to the information collected during the previous step of scanning the surface S of the glass V. The robot 3 is deployed to bring the print head 22 close to the surface S of the glass V, parallel to this surface S. The printing nozzle is oriented towards the glass, for example at a distance between 1 and 3 mm, so as to completely cover the glass, and permanently perpendicular to the curve of the glass V. The trajectory followed by the print head 22 carried by the robot 3 allows the ink to be deposited on the entire surface S of the glass V, if necessary, while adapting to the shape and curve of the glass V, so as to maintain a constant distance between the glass V and the print head 22 by means of the distance maintenance means 25.

[0070] Reference Figure 3, it can be seen that it shows a top view of the surface S of the glass V printed by the device 1 for printing on glass of the present invention according to the scanning pattern. The scanning pattern is a contiguous strip, wherein the print head 22 preferably moves continuously in two different directions indicated by the arrows on the contiguous strips B1, B2, B3, B4. The print head 22 moves on the glass V carried by the holder 2, guided by the robot 3 so as to always orient the print nozzle perpendicularly to the surface S, in particular perpendicularly to the curve of the glass V when the glass to be printed is curved. The print head 22 is able to print the pattern corresponding to the strips B1, B2, B3, B4 over the entire width of the pattern, regardless of the direction in which it moves on the glass V. It is therefore possible to run parallel to the edge C over the length of the glass V. At the end of the strip B1, the robot 3 allows the print head 22 to rotate 180° and shift the width of the print head 22 so as to quickly print the second strip B2 in the opposite direction to the first strip B1. It is conceivable that the printing on the glass V is triggered by optical means upstream of the printing head 21 , thus allowing the edge C of the glass V to be identified. The reduction in the number of unnecessary movements ensures a reduction in the glass processing time.

[0071] It should be noted that a person skilled in the art will be able to define a scanning pattern suitable for the printing requirements to be performed.For example, the scanning pattern may include a return to the starting edge of the strip at the end of printing of the strip.

[0072] Since there may be a gap of up to 3 mm between two 3D formed glass products of the same type, for example, two consecutive glass products of the same type are not identical and therefore do not support the same print head settings, which may be optimal for one glass product and result in an offset, or even contact, between the print head and the surface for another glass product. To address this issue, the following solutions can be envisaged: 3D scanning of the glass surface before printing; print heads equipped with confocal or laser triangulation distance sensors to adjust the distance in real time; glass shape constraints, such as using suction cups.

[0073] The deposition on the glass V can be continuous or localized.

[0074] Reference Figure 4 , it can be seen that it shows a device 101 for printing on glass according to the second embodiment of the present invention.

[0075] The apparatus 101 for printing on glass is similar to the apparatus 1 for printing on glass according to the first embodiment described above. The elements of the apparatus 1 for printing on glass of the first embodiment are the same as or similar to those of the apparatus 1 for printing on glass and are referred to as such. Figure 1 The elements of the described device for printing on glass will carry the same reference numerals plus 100 and will not be described in more detail here.

[0076] The apparatus 101 for printing on glass according to the second embodiment includes two robots 103A and 103B.

[0077] The respective bases 106A and 106B of the robots 103A and 103B are arranged at the same height as the holder 102 and are located on both sides of the holder 102. However, this example is illustrative, and those skilled in the art will understand that the robots can take any shape and any arrangement as long as they cover the surface of the glass assigned to them, depending on the available space constraints.

[0078] With this configuration, each of the robots 103A and 103B performs printing on the half MA, MB of the surface S of the glass V.

[0079] Therefore, the present invention allows different robot / ink combinations, such as: one robot 3, 103A, 103B, one ink; one robot 3, 103A, 103B, two inks; two robots 3, 103A, 103B, one ink, or two robots 3, 103A, 103B, two inks.

[0080] It should be noted that a person skilled in the art may employ any number of robots and print heads in the apparatus for printing on glass according to the present invention, depending on the requirements of the printing to be performed, without departing from the scope of the present invention.

[0081] Reference Figure 5 , it can be seen that it shows a schematic diagram of a machine 29 for printing on glass according to the invention.

[0082] The machine comprises, arranged in sequence: a glass loading station 30, a glass washing station 31, an optional glass scanning station 32, a glass surface preparation station 33, a printing station 34 equipped with the device 1, 101 for printing on glass as described above, a drying station 35, a control station 36 and an unloading station 37. The machine 29 also comprises means for conveying glass between two adjacent stations 30, 31, 32, 33, 34, 35, 36, 37.

[0083] Advantageously, the machine 29 also comprises a post-processing station between the drying station 35 and the control station 36, for example for post-printing deposition of an adhesive primer in order to maximize the adhesion between the glass and the polyvinyl butyral (PVB) interlayer in the manufacture of laminated glass.

[0084] The machine 29 may include a computer to control the entire process, synchronize steps and share information.

[0085] The machine 29 is capable of working sequentially, which means that a different glass is simultaneously in each station 30, 31, 32, 33, 34, 35, 36, 37 and undergoes the steps of the process associated with that station. All glass products are transferred to the next station simultaneously. This means that the cycle time of the machine 29 corresponds to the cycle time of the longest process step.

[0086] If necessary, the glass V is first bent using a conventional bending process. At the end of this step, the 3D glass V is transferred to a printing machine 29 .

[0087] At the glass loading station 30 , the glass V is loaded onto the machine 29 , onto a conveyor, onto a cart or by a robot in charge of taking it from one station to another, which constitutes the glass transport means.

[0088] At the glass washing station 31 , the machine 29 comprises a washing machine for 3D washing the glass product V. This step may be optional if the printing process is located directly at the exit of the 3D washing machine before assembly with the PVB type interlayer.

[0089] At the glass scanning station 32, the machine 29 comprises a scanner for identifying and acquiring the precise size, positioning and curvature of the glass V. This information is then transmitted to the robot 3, 103A, 103B used during the printing phase at the printing station 34, so that it can adapt its trajectory to the actual size of each glass V. The recognition of the pattern of glass V also allows the automatic selection of the printing process to be applied.

[0090] At the glass surface preparation station 33, an adhesion primer type coating or a plasma or corona type surface treatment may be deposited.

[0091] At the drying station 35, drying can be performed using UV lamps. The UV lamps are arranged on vertically movable articulated tracks. The width of the UV lamps makes it possible to dry the entire width of the glass V simply by moving the glass V under the row of UV lamps. The speed at which the glass V moves can be adjusted, as can the vertical distance between the lamps and the glass V, in order to adapt the UV dose received by each type of glass.

[0092] The control station 36 can be equipped with a camera for visual inspection of the glass V and detection of any defects. If the part is free of defects, it is unloaded at the exit of the machine. Otherwise, it is directed to glass recycling.

[0093] Between the printing station and the drying station, the machine 29 may include a station configured to perform a visual inspection before the drying stage, so that the coating can be easily removed if necessary.

[0094] A dedicated station may also be provided to put the glass V through the production cycle again in the event of defects during the printing phase (ink cleanout, ink burnout in a high-temperature oven, glass conversion into cullet, etc.).

[0095] Finally, the present invention relates to a method for printing on glass by implementing the device 1, 101 for printing on glass as described above. The method comprises the steps of loading a glass product V on the surface of which printing is to be performed on a holder S, printing the surface S of the glass V by the device 1, 101 for printing on glass as described above, and unloading the printed glass.

[0096] The printing step may comprise scanning the surface S according to a pattern of scanning adjacent strips as described above.

[0097] The present invention allows the ink to be directly printed onto the glass product V in 3D form after the glass V bending step, and has the following advantages: - In the case of single-side two-print or single-side three-print applications, energy is saved and production is increased by eliminating the ink pre-curing step; - The ink no longer needs to have anti-stick properties because the glass article is bent before the ink is printed; - Since the present invention allows the use of organic digital inks which are more common than ceramic digital inks, the range of inks that can potentially be used is wider; - Reduced risk of optical distortion since there is no ink on the glass during bending; - Reduced risk of glass breakage for the same reasons as above; - In case of side 1 or side 4 deposition, ink deposition can be before or after the lamination step; - The option to produce personalized or customized designs without the need to change tools or screens as in screen printing; - Improved deposition accuracy through true knowledge of the speed at which the glass is moving relative to the print head.

[0098] The invention is particularly suitable for all types of glass used in the automotive or architectural markets, especially non-flat glass products.

[0099] It should be understood that the embodiments just described are indicative and non-limiting, and that further embodiments may be added without departing from the scope of the present invention.

[0100] Thus, while the glass is shown in the figures as being flat, it should be understood that the invention is not limited in this regard and that the apparatus, machine and method of the invention are also applicable when the glass already has a three-dimensional shape.

[0101] Similarly, for simplicity, only one print head per robot is shown in the figure. The present invention is still not limited in this respect, and a robot according to the present invention may carry multiple print heads simultaneously without departing from the scope of the present invention.

Claims

1. A device for printing on glass (1; 101), characterized in that it comprises: a holder (2; 102) configured to receive a glass product (V) on at least one surface (S) of which printing is to be performed; at least one robot (3; 103A, 103B) configured to move an arm (5) along six axes, said arm (5) having one end connected to a base (6) and an opposite free end; a printing tool (21), the printing tool (21) comprising at least one printing head (22), the at least one printing head (22) being configured to be mounted on the free end of the arm (5) of the at least one robot (3; 103A, 103B); a speed sensor (24) configured to detect a relative printing speed of the at least one print head (22) relative to the at least one surface (S) of the glass (V); a distance maintaining device (25) configured to maintain a constant distance between the at least one print head (22) and the at least one surface (S) of the glass (V); A control device (26) configured to control the movement of the at least one robot (3; 103A, 103B), adjust the movement speed of the at least one print head (22) according to the relative printing speed, and adjust the distance between the at least one print head (22) and the at least one surface (S) of the glass (V) through the distance maintaining device (25).

2. The device (1; 101) for printing on glass according to claim 1, characterized in that The at least one print head (22) is of the fast loading and unloading type.

3. The device (1; 101) for printing on glass according to claim 1 or 2, characterized in that The distance maintaining device (25) is at least one of: a system for constraining the glass according to a predetermined shape, preferably by means of a suction cup; a system for scanning the surface (S) of the glass (V) to record its shape; and a distance sensor carried by the printing tool (21).

4. The device (1; 101) for printing on glass according to any one of claims 1 to 3, characterized in that The control device (26) is composed of at least one of the following: a microcontroller; a processor; a microprocessor; a digital signal processor (DSP); a field programmable gate array (FPGA); an application specific component (ASIC); a computer, which includes software configured to control the robot, the printing tool and the distance maintaining device.

5. The device (1; 101) for printing on glass according to any one of claims 1 to 4, characterized in that The at least one robot (3; 103A, 103B) is configured to move the at least one print head (22) according to an adjacent strip scanning pattern, preferably continuously in two different directions on two adjacent strips to reduce printing time.

6. The device (1) for printing on glass according to any one of claims 1 to 5, characterized in that It comprises a single robot (3) and a gantry (23), the robot (3) being attached to the gantry (23) via its base (6) such that the base (6) is arranged above the holder (2).

7. The device (101) for printing on glass according to any one of claims 1 to 5, characterized in that: It comprises two robots (103A, 103B), the bases of which are preferably arranged at the same height as the holder and on both sides of the holder.

8. The device (101) for printing on glass according to claim 7, characterized in that Each robot (103A, 103B) performs printing on at least half of the surface (S) of the glass (V).

9. The device (1; 101) for printing on glass according to any one of claims 1 to 8, characterized in that It also comprises at least one additional print head (27) and a device (28) for replacing the at least one print head (22), the device (28) being configured to replace the at least one print head (22) with the at least one additional print head (27), preferably by pneumatic or magnetic loading and unloading.

10. A machine (29) for printing on glass, characterized in that It includes, arranged in order: Glass loading station (30); Glass washing station (31); optional glass scanning station (32); glass surface preparation station (33); a printing station (34) equipped with a device for printing on glass according to any one of claims 1 to 9; Drying station (35); Control station (36); an unloading station (37); and Two adjacent stations are connected by glass conveying means, preferably rollers or a conveyor belt.

11. Machine (29) for printing on glass according to claim 10, characterized in that It also comprises a post-treatment station (PT) between said drying station (35) and said control station (36).

12. A method for printing on glass using the device (1; 101) for printing on glass according to any one of claims 1 to 9, characterized in that It includes: loading the holder (2) with a glass product (V) on at least one surface (S) of which printing is to be performed; Printing on the surface (S) of the glass product (V); Unload the printed glass product (V).

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