Device 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), characterised 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 print head (22), a speed sensor configured to detect the relative printing speed of the at least one print head (22) relative to a surface (S) of the glass (V), distance-maintaining 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 movements of the robot (3), adjust the speed of movement of the at least one print head (22) depending on the relative printing speed and adjust the distance between the at least one print head (22) and the surface (S) of the glass (V).

Description

[0001] Description

[0002] Title of the invention: Glass printing device, glass printing machine and glass printing method

[0003] The present invention relates to the field of printing, and more particularly to a glass printing device, a glass printing machine and a glass printing method.

[0004] Digital printing (also called digital printing or inkjet printing) is commonly used for coating on flat two-dimensional glass. In this case, the glass usually moves on rollers or on a conveyor belt at a constant altitude. The print heads move above the glass, at a distance from the glass of between 0.5 and 3 mm at a constant altitude, which makes it easy to maintain a constant distance between the print heads and the glass. During printing, the glass and / or the print heads are moving along the X-axis and the Y-axis at a constant speed. For reasons of cycle time savings, the coating is preferably deposited in a single pass, which means that the print head only passes once over each point of the glass, as opposed to multiple passes.

[0005] For applications such as digital printing on automotive glass, such as windshields, printing is carried out on the flat glass, before any bending or lamination step. The glass only takes its final three-dimensional shape once the printing process is complete, at the end of the bending step. For this reason, the inks used are ceramic or enamel-based inks, which must be able to withstand temperatures above 600 °C, encountered during the current subsequent three-dimensional shaping steps of the glass (bending, lamination). In addition, for some applications, several ink curing steps are necessary, particularly for the development of specific properties for the ink such as anti-stick.

[0006] The digital printing coating process can be applied to everyday three-dimensional objects made of glass or other materials. These objects are generally cylindrical in shape, for example bottles, glasses, flasks, etc. These objects are then rotated along their axis of symmetry while a print head moves over the object, perpendicular to this axis of rotation.

[0007] Patent US10933626B1 discloses a device for decorating the outer surface of objects such as beverage containers by digital printing. The object to be decorated is cylindrical in shape. A device makes it possible to impose a rotational movement on the object to be decorated along its axis of symmetry at the speed of its choice. A turret-type device is equipped with digital printing stations and ink drying stations arranged in an arc above the part to be printed. The turret-type device makes it possible to bring the desired station above the object to be printed while the latter rotates on itself in order to carry out the digital printing. Patent application US20130222498A1 describes a machine for depositing ceramic-type ink on flat glazing by digital printing. The glass is placed horizontally on the machine plate.The digital print head is fixed on a ramp located above the glazing and moves above it so as to cover its entire surface. The machine is equipped with a system for drying the ink in order to be able to direct the glazing in a second step towards a firing oven in which the glass will be shaped. 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 in order to print a flat surface. The invention then makes it possible to orient the four heads each at a specific angle in order to orient them in an arc of a circle, making it possible to print on the concave face of a cylindrical object and to adapt to the radius of curvature of the latter.This patent describes a system in which the print heads are tiltable but with a limited number of positions and configurations.

[0008] 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. This invention describes a step of scanning the surface to be printed, making it possible to generate a set of points constituting the trajectory to be followed by the robot to carry out the digital printing as well as a step of digital printing using the print head.

[0009] Patent application US2021300061A1 describes a method for decorating three-dimensional objects that enables digital printing on three-dimensional objects using a machine equipped with a six-axis robot. This robot allows the transport of three-dimensional objects in front of fixed digital print heads.

[0010] When making a deposit by digital printing on a surface, droplets are ejected towards the surface to be printed. Due to the size of the droplets, a few picoliters (pL), and in order to ensure a homogeneous deposit respecting the shape of the image that one wishes to print, it is essential to maintain at all times a constant distance between the surface to be printed and the print head, as well as a constant relative speed between the print head and the surface to be printed.

[0011] Furthermore, in the case of windshields, the ink printing, exclusively of the ceramic type, is carried out before bending on flat glass. The ink is exclusively of the ceramic type, and not organic since the glass is then shaped in a bending oven at temperatures above 600 °C, which limits the number of usable ink references. In addition, these inks must have anti-stick properties in the case of applications on side 2 or side 3, which further restricts the range of usable inks. Before lamination, a laminated glass consists of two panes, each with two sides, which defines a four-sided system: side 1 corresponds to the side that will be on the outside of the vehicle in the context of automotive glazing,

[0012] - face 2 corresponds to the face directly opposite face 1 and located on the same glass before lamination and in contact with the interlayer sheet (for example PVB (polyvinyl butyral)),

[0013] - face 3 corresponds to the face in contact with the other side of the interlayer sheet, and

[0014] - face 4 corresponds to the face directly opposite face 3 and located on the same glass before lamination, and it is also the face which will be located inside the vehicle, in direct contact with the passenger(s) of the vehicle.

[0015] Finally, a specific ink pre-baking step is necessary, which has the consequence of increasing energy consumption for each windshield manufactured, as well as generating quality defects on the glazing.

[0016] Furthermore, examples of digital printing on three-dimensional (3D) objects, whether glass or not, are limited to objects with an axis of symmetry and large radii of curvature, for example bottles, flasks, water bottles, baseball bats, etc. In this case, during the printing phase, the objects are subjected to a rotational movement along this axis of symmetry. The print head moves above the rotating object, parallel to its axis of rotation. This ensures a uniform speed for both the rotating object and the print head, and printing takes place almost on a flat surface. This configuration cannot be applied to large glass objects such as roof windows or windshields.

[0017] Finally, although commercially available six-axis robots operating as "carried parts" guarantee high spatial precision, i.e. systematic passage through the same points during a path or trajectory, they do not guarantee temporal precision, i.e. passage at a strictly constant speed throughout the entire path. Very sudden and rapid fluctuations around the set speed of + / - 10% are observed. Thus, in the context of a digital printing application, the print heads adapting the drop ejection frequency to the set speed applied to the robot and not to the actual speed of the robot at any time, it is possible to observe defects in the patterns printed with this method, some drops being ejected too early onto the glass, others too late due to speed variations.This results in dot placement errors as well as areas that are too rich in ink and areas that are too depleted in ink.

[0018] There is therefore a need for a device, a machine and a process for printing on glass which allow precise and controlled printing, guaranteeing a homogeneous and lasting deposit on objects of varied geometries.

[0019] The Applicant therefore proposes to meet these needs by using a device, a machine and a method implementing a six-axis robot allowing the printing heads to be tilted according to an infinite number of positions and configurations, a device for measuring in real time the speed of the printing head relative to the object to be decorated, and means for maintaining the distance between the printing head and the glass.

[0020] The present invention therefore relates to a device for printing on glass, characterized in that it comprises: a support configured to receive a glass on at least one surface of which printing is to be carried out; at least one robot configured to move an arm along six axes, the arm having one end connected to a base and an opposite free end; a printing tool, the printing tool comprising at least one print head configured to be mounted on the free end of the arm of the at least one robot; a speed sensor, configured to detect the relative printing speed of the at least one print head with respect to the at least one surface of the glass; distance maintaining means, configured to maintain a constant distance between the at least one print head and the at least one surface of the glass;control means configured to control the movements of the at least one robot, adjust the speed of movement of the at least one print head as a function of the relative printing speed and adjust the distance between the at least one print head and the at least one surface of the glass by means of the distance maintaining means.;

[0021] Thus, such a device allows, jointly and in real time, the detection of the relative speed of the at least one print head with respect to the surface of the glass and the maintenance of a constant distance between the at least one print head and the surface of the glass. The printing is reliably reproducible even if there are differences in shape (curve) and thickness between two glasses.

[0022] Furthermore, detecting in real time the relative speed of the at least one print head with respect to the glass surface allows print head movement speeds of at least 200 mm / s and combining relative speed detection and distance maintenance leads to very short cycle times to reduce the printing time, which is particularly advantageous in the field of automotive glass production (between 20 and 40 s / glass).

[0023] In addition, the speed sensor makes it possible to overcome the temporal precision defects of six-axis robots, during the first execution of each trajectory, making it possible to measure in real time the relative instantaneous speed of the at least one print head in relation to the glass. This measurement is then transmitted to the at least one print head which adapts in real time its droplet ejection frequency according to where it is located above the glass. Thus the precision of droplet deposition is improved and printing defects are reduced.

[0024] The glass printing device according to the present invention makes it possible to keep the glass fixed during printing, the at least one print head being movable and moving above the glass.

[0025] The glass printing device according to the present invention makes it possible to print the ink after the glass shaping step. The use of a six-axis robot makes it possible to tilt the print heads in an infinite number of positions and configurations. Thus, the glass printing device according to the present invention is particularly suitable for printing on objects of very varied geometries and thus makes it possible to create decorations on windshield or roof window type glass, or when the entire surface must be decorated.

[0026] Furthermore, because the three-dimensional shaping steps of the glass can be carried out after printing, the constraints on the inks are less, and a wider choice of inks is therefore offered. According to one embodiment, the at least one print head is fast-loading and fast-unloading, for example pneumatic or magnetic. The robot tool changers of the Schunk ® brand thus allow, for example, a fast tool change on a robot head. Thus, it is possible to successively print different ink references with minimal loss of time.

[0027] According to one embodiment, the distance maintaining means are at least one of a system for constraining the glass into a predetermined shape, preferably by suction cups, a system for scanning the surface of the glass to record its shape and a distance sensor carried by the printing tool.

[0028] According to one embodiment, the control means are constituted by at least one of a microcontroller, a processor, a microprocessor, a digital signal processor (DSP), a field programmable gate array (FPGA), an application-specific component (ASIC), a computer, comprising software configured to control the robot, the printing tool and the distance-maintaining means.

[0029] According to one embodiment, the at least one robot is configured to move the at least one print head according to a scanning pattern in adjacent bands, preferably moving continuously in two different directions on two adjacent bands to reduce the printing time. This provides continuous printing, without unnecessary movement of the at least one print head. According to one embodiment, the glass printing device comprises a single robot and a gantry, the robot being fixed by its base to the gantry so that the base is arranged above the support. According to one embodiment, the glass printing device comprises two robots, the bases of the robots being preferably arranged at the same height as the support and on either side of the support.

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

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

[0032] Thus, the changing means allow printing different colors or inks on the same glass with a single glass printing device, and also allows ink A on a type of glass A' and ink B on a type of glass B'. Finally, in the event of maintenance on a print head, there remains an operational print head, which allows continuous and uninterrupted operation of the machine.

[0033] The present invention also relates to a glass printing machine, characterized in that it comprises, arranged successively: a glass loading station; a glass washing station; an optional glass scanning station; a glass surface preparation station; a printing station equipped with a glass printing device as described above; a drying station; a control station; an unloading station; and two adjacent stations being connected by glass conveying devices, preferably rollers or a conveyor belt.

[0034] Thus, the use of several modular stations allows the machine to operate sequentially and process several glazings at the same time. The configuration of the printing station is modular since it can be equipped with several robots to reduce the cycle time.

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

[0036] The present invention also relates to a method for printing on glass using a glass printing device as described above, characterized in that it comprises: loading onto the support a glass on at least one surface of which a print is to be made; printing on the surface of the glass; unloading the printed glass.

[0037] To better illustrate the object of the present invention, several embodiments will be described below, for informational and non-limiting purposes, with reference to the attached drawings.

[0038] On these drawings

[0039] [Fig. 1] is a perspective view of a glass printing device according to a first embodiment of the present invention;

[0040] [Fig. 2] is a schematic representation of the glass printing device according to [Fig. 1]; [Fig. 3] is a top view of a glass printed by the glass printing device of the present invention in a scanning pattern;

[0041] [Fig. 4] is a perspective view of a glass printing device according to a second embodiment of the present invention; and

[0042] [Fig. 5] is a schematic representation of a glass printing machine according to the present invention.

[0043] Referring to Figure 1, it can be seen that there is shown a glass printing device 1 according to a first embodiment of the present invention.

[0044] The glass printing device 1 comprises a support 2. The support 2 may be any printing support known to those skilled in the art capable of receiving an object on which printing is to be carried out. The support 2 may be fixed. In this case, handling tools will load onto it the glass V on which printing is to be carried out. The support 2 may be mobile, for example, being placed on a conveyor.

[0045] The glass printing device 1 also comprises a robot 3. The robot 3 is a six-axis type robot. As can be seen in Figure 1, and as well known to those skilled in the art, the robot 3 comprises a base 4 and an articulated arm 5.

[0046] The base 4 has a flat mounting face 6 by which the base 4 is capable of being mounted on an external chassis.

[0047] The arm 5 has 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 by a shoulder 9. The shoulder 9 is rotatable relative to the base 4, along a first axis 10 perpendicular to the mounting face 6.

[0048] The arm 5 comprises a hind arm 11. The hind arm 11 is pivotally connected to the shoulder 9 along a second axis 12 perpendicular to the first axis 10.

[0049] The arm 5 has an elbow 13. The elbow 13 is pivotally connected to the rear arm 11 along a third axis 14 parallel to the second axis 12.

[0050] The arm 5 comprises a forearm 15. The forearm 15 is rotatable relative to the elbow 13 along a fourth axis 16 perpendicular to the third axis 14 and extending in the longitudinal direction of the forearm 15.

[0051] 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.

[0052] The arm 5 comprises a second wrist 19, at the distal end 8 of the arm 5. The second wrist 19 is connected in rotation to the first wrist 17 along a sixth axis 20 perpendicular to the fifth axis 18.

[0053] Thus, robot 3 is configured to move arm 5 along six axes.

[0054] The glass printing device 1 also comprises a printing tool 21.

[0055] In Figure 1, it can be seen that the printing tool 21 comprises a printing head 22, mounted at the distal end 8 of the arm 5, on the second wrist 19. It is understood that a person skilled in the art will be able to choose any printing heads adapted to the needs of the printing to be carried out, such as for example the number and nature of the nozzles as well as their arrangement. It should also be noted that a person skilled in the art will likewise be able to choose any printing tool adapted to the needs of the printing to be carried out, in particular all necessary configurations and equipment, such as for example supply pipes, an ink tank and a 24 / 7 ink recirculation system, which remain stationary. These will not be described in more detail here.

[0056] According to the first embodiment shown in Figure 1, the robot 3 is arranged above the support 2. To do this, the robot 3 is mounted on a gantry 23 such that the mounting plane 6 is parallel to the support 2. Preferably, the glass printing device 1 is configured such that during printing, the center of the base 4 is vertical to the center of the surface S of the glass V on which the printing is to be carried out. During printing, the arm 5 of the robot 3 is extended towards the glass V located below.

[0057] It should be noted that the glass printing device 1 according to the present invention is suitable for printing on several surfaces of the same glass object, for example on both sides of a windshield.

[0058] Below each print head 22 there may be a low-power UV lamp for freezing the ink droplets without drying them completely so as to avoid dripping while the entire surface S of the glass V is printed. This UV lamp should be oriented appropriately so as not to observe any reflection of the UV rays towards the print head 22 which would cause polymerization of the ink on the surface of the print head 22. A similar IR fixing system (IR pinning in English) in the case of IR ink or hot air fixing in the case of thermal ink is also conceivable.

[0059] As can be seen in the schematic representation of Figure 2, the glass printing device 1 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 carried out.

[0060] Preferably, the speed sensor 24 is located near the print head 22, or even directly on the print head.

[0061] The glass printing device 1 also comprises distance maintaining means 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 carried out.

[0062] The distance maintaining means 25 are at least one of a system for constraining the glass into a predetermined shape, preferably by suction cups, a system for scanning the surface of the glass to record its shape and a distance sensor carried by the printing tool 21.

[0063] Thus, for example, according to the first variant of a glass constraining system, a frame provided with suction cups can very precisely constrain a glass into a predetermined shape and on the basis of which the movement of the at least one print head is preprogrammed.

[0064] According to the second variant, each glass is scanned by a shape detection tool (laser scanning, camera with image processing software) to precisely determine the shape of each glass and adapt the path of the at least one print head accordingly. According to the third variant, a distance sensor, which can be carried by the robot, the at least one print head, or another means (camera with image processing software) calculates in real time the distance between the at least one print head and the surface of the glass to adapt the path of the at least one print head accordingly to always maintain a predetermined distance between these two elements.

[0065] The glass printing device 1 further comprises control means 26. The control means 26 are connected to the robot 3, to the print head 22, to the speed sensor 24 and to the distance maintaining means 25. The control means 26 are configured to control the movements of the robot 3, to adjust the speed of movement of the print head 22 according to the relative printing speed detected by the speed sensor 24, and to adjust the distance between the print head 22 and the surface S of the glass V on which printing is to be carried out by means of the distance maintaining means 25. The control means 26 are also configured to control the printing according to a predefined scanning pattern.

[0066] The control means 26 are constituted by at least one of a microcontroller, a processor, a microprocessor, a digital signal processor (DSP), a field programmable gate array (FPGA), an application specific component (ASIC), a computer, comprising software configured to control the robot 3, the printing tool 21 and the distance maintaining means 25. In Figure 2, it can be seen that the printing device 1 may additionally and optionally comprise an additional print head 27. The additional print head 27 constitutes a replacement head for the same ink or a different ink, for example different colors or different structures, natures or constitutions. Advantageously, the additional print head 27 may be stored on a storage rack.Advantageously, the print heads 22, 27 are of the rapid loading and unloading type, for example of the pneumatic or magnetic type.

[0067] In this case, the glass printing device 1 is equipped with print head changing means 28, configured to replace the print head 22 mounted at the distal end 8 of the arm 5 with an additional print head 27. The print head changing means 28 are of the type well known to those skilled in the art, preferably by pneumatic or magnetic loading and unloading.

[0068] The replaced printhead 22 can be placed on a storage rack.

[0069] 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 to be carried out as well as the number and nature of the print head changing means 28.

[0070] During the printing phase, the glass V is stationary, all of the movements are carried out by the robot 3. The trajectory of the robot 3 adapts according to the information collected during a prior step of scanning the surface S of the glass V. The robot 3 deploys to approach the print head 22 close to the surface S of the glass V, parallel to this surface S. The printing nozzles are oriented towards the glass, for example at a distance of between 1 and 3 mm so as to be able to cover it completely, 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 deposition of ink 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, thanks to the distance maintaining means 25.

[0071] Referring to Figure 3, it can be seen that there is shown a top view of the surface S of the glass V printed by the glass printing device 1 of the present invention according to a scanning pattern. The scanning pattern is in adjacent bands, the print head 22 preferably moving continuously in two different directions, indicated by the arrows, on adjacent bands B1, B2, B3, B4. The print head 22 moves above the glass V carried by the support 2, directed by the robot 3 so as to permanently orient the printing nozzles perpendicular to the surface S, in particular to the curve of the glass V when the glass to be printed is curved. The print head 22 is capable of printing patterns over its entire width, corresponding to a band B1, B2, B3, B4, regardless of the direction in which it moves above the glass V.Thus, it is possible to run a first strip B1 along the length of the glass V, parallel to the edge C. At the end of the strip B1, the robot 3 allows the print head 22 to rotate 180°C and shift by a width of the print head 22 in order to quickly continue with the printing of a second strip B2, in the opposite direction relative to the first strip B1. It may be possible for the printing on the glass V to be triggered by an optical device upstream of the print head 21 making it possible to recognize the edge C of the glass V. Reducing the number of unnecessary movements ensures a saving in glass processing time. It should be noted that a person skilled in the art will be able to define the scanning pattern adapted to the needs of the printing to be carried out. For example, the scanning pattern may include, at the end of the printing of the strip, a return to the starting edge of the strip.

[0072] Because there may be, for example, gaps of up to 3 mm between two 3D-formed glasses of the same type, two successive glasses of the same type are not identical and therefore do not support the same print head settings, which may be optimal for one glass and lead to an offset, or even contact of the print head with the surface, for another glass. To remedy this, the following solutions can be considered: 3D scan of the glass surface before printing; print head equipped with a confocal or laser triangulation type distance sensor to adjust the distance in real time; constraint of the shape of the glass, by suction cups for example.

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

[0074] Referring to Figure 4, it can be seen that there is shown a glass printing device 101 according to a second embodiment of the present invention.

[0075] The glass printing device 101 is similar to the glass printing device 1 according to the first embodiment described above. Elements of the glass printing device identical or analogous to the elements of the glass printing device 1 of the first embodiment, and described with reference to Figure 1, will bear the same reference numeral increased by 100, and will not be described in further detail here. The glass printing device 101 according to the second embodiment comprises two robots 103A and 103B.

[0076] The respective bases 106A and 106B of the robots 103A and 103B are arranged at the same height as the support 102 and on either side of the support 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 allocated to them, depending on the constraints of available space.

[0077] Thanks to such a configuration, each robot 103A and 103B performs a print on a half MA, MB of the surface S of the glass V.

[0078] The present invention thus 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 even two robots 3, 103A, 103B, two inks.

[0079] It should be noted that any number of robots and print heads may be used by those skilled in the art in the glass printing device according to the present invention depending on the needs of the printing to be carried out, without departing from the scope of the present invention.

[0080] Referring to Figure 5, it can be seen that there is shown a diagram of a glass printing machine 29 according to the present invention.

[0081] The machine comprises, arranged successively: a glass loading station 30, a glass washing station 31, a glass scanning station 32 which is optional, a glass surface preparation station 33, a printing station 34 equipped with a glass printing device 1, 101 as described previously, a drying station 35, a control station 36 and an unloading station 37. The machine 29 also comprises means for conveying the glass between two adjacent stations 30, 31, 32, 33, 34, 35, 36, 37.

[0082] Advantageously, the machine 29 further comprises a post-treatment station between the drying station 35 and the control station 36, for example for the post-printing deposition of an adhesion primer, in order to maximize the adhesion between the glass and the interlayer sheet of poly(vinyl butyral) (PVB) type in the context of the manufacture of laminated glazing.

[0083] Machine 29 may include a computer controlling everything and ensuring the synchronization of the steps and the sharing of information.

[0084] 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 process step associated with the station. Transfer to the next station is carried out simultaneously for all the glasses. This means that the cycle time of machine 29 corresponds to the cycle time of the longest process step.

[0085] If necessary, the V-glass is first curved using the usual curving processes. At the end of this step, the 3D V-glass is brought to the printing machine 29. At the glass loading station 30, the V-glass is loaded onto the machine 29, onto a conveyor, onto a trolley or via a robot responsible for taking it from station to station, constituting the means for conveying the glass.

[0086] At the glass washing station 31, the machine 29 includes a washing machine for washing a V-shaped glass in 3D. This step may be optional if the printing process is positioned directly at the outlet of the 3D washing machine preceding assembly with the PVB-type interlayer sheet.

[0087] At the glass scanning station 32, the machine 29 comprises a scanner enabling recognition and acquisition of the dimensions, positioning and exact 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 adapts its trajectory to the actual dimensions of each glass V. Recognition of the format of the glass V also enables automatic selection of the printing process to be applied.

[0088] At the glass surface preparation station 33, it is possible to carry out a deposit of adhesion primer type coating or a plasma or Corona type surface treatment.

[0089] At the drying station 35, drying can be carried out using UV lamp(s). The UV lamps are arranged on an articulated rail which can move in height. The width of the UV lamps makes it possible to dry the glass V in its entire width simply by passing the glass V under the row of UV lamps. The speed of passage of the glass V can be modulated, as can the vertical distance between the lamps and the glass V, so as to adapt the UV dose received by each type of glass.

[0090] The inspection station 36 may be equipped with a camera for visually inspecting the glass V and detecting the presence of any defects. If the part does not contain any defects, it is unloaded at the machine outlet. Otherwise, it is sent for glass recycling. The machine 29 may comprise, between the printing station and the drying station, a station configured for visual inspection before the drying step in order to easily remove a coating if necessary.

[0091] A specific station can also be provided to, in the event of defects during the printing phase, re-enter the V glass in the production cycle (ink cleaning, ink burned in a high temperature oven, glass transformed into cullet, etc.).

[0092] The present invention finally relates to a method for printing on glass using a glass printing device 1, 101 as described above. The method comprises the steps of loading onto the support S a glass V on a surface of which printing is to be carried out, carrying out printing on the surface S of the glass V by the glass printing device 1, 101 as described above and unloading the printed glass.

[0093] The printing step may comprise scanning the surface S in an adjacent stripe scanning pattern as described above.

[0094] The present invention allows the printing of ink directly onto a V-glass in 3D, after the V-glass bending step and has the following advantages: energy saving and improvement of the yield by eliminating the ink pre-baking step in the case of an application on one side two or one side three; - the ink no longer has to have anti-stick properties, the glasses being bent before printing the ink; the range of potentially usable ink is wider because the invention allows the use of organic digital inks, more widespread than ceramic digital inks; - the risk of optical distortions is reduced because there is no ink on the glass during bending;

[0095] - reduction of the risk of glass breakage for the same reasons as for the previous point;

[0096] - ink deposition either before or after the lamination step in the case of deposition on face one or face four; possibility of producing single or personalized patterns without changing tools or screens as in screen printing; improvement of deposition precision through real knowledge of the speed of movement of the glass in relation to the print heads.

[0097] The present invention is particularly suitable for all types of glass for the automotive or construction market, in particular non-flat glass.

[0098] It is understood that the embodiments which have just been described have been given for informational and non-limiting purposes and that embodiments may be added thereto without departing from the scope of the present invention.

[0099] Thus, although the glass shown in the figures is flat, it is clearly understood that the invention is not limited in this respect and that the device, machine and method of the invention are applicable when the glass already has a three-dimensional shape.

[0100] Likewise, for the sake of simplification, only one print head per robot has been shown in the figures. The invention is still not limited in this respect, and a robot according to the invention could carry several print heads simultaneously, without departing from the scope of the present invention.

Claims

Demands

1. - A glass printing device (1; 101), characterized in that it comprises: a support (2; 102) configured to receive a glass (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, the 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 print head (22) configured to be mounted on the free end of the arm (5) of at least one robot (3; 103A, 103B); a speed sensor (24), configured to detect the relative printing speed of at least one print head (22) with respect to at least one surface (S) of the glass (V); distance maintenance means (25), configured to maintain a constant distance between at least one print head (22) and at least one surface (S) of the glass (V);control means (26) configured to control the movements of at least one robot (3; 103A, 103B), adjust the speed of movement of at least one print head (22) according to the relative printing speed and adjust the distance between at least one print head (22) and at least one surface (S) of the glass (V) by means of the distance maintenance means (25).

2. - Glass printing device (1; 101) according to claim 1, characterized in that at least one print head (22) is fast loading and unloading.

3. - Glass printing device (1; 101) according to claim 1 or claim 2, characterized in that the distance maintenance means (25) are at least one of a system for constraining the glass according to a predetermined shape, preferably by suction cups, 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. - Glass printing device (1; 101) according to any one of claims 1 to 3, characterized in that the control means (26) consist of at least one of a microcontroller, a processor, a microprocessor, a digital signal processor (DSP), a field-programmable pre-diffused array (FPGA), an application-specific integrated circuit (ASIC), a computer, comprising software configured to control the robot, the printing tool and the distance-maintaining means.

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

6. - Glass printing device (1) according to any one of claims 1 to 5, characterized by the fact that it comprises a single robot (3) and a gantry (23), the robot (3) being fixed by its base (6) to the gantry (23) so that the base (6) is positioned above the support (2).

7. - Glass printing device (101) according to any one of claims 1 to 5, characterized in that it comprises two robots (103A, 103B), the bases of the robots (103A, 103B) preferably being arranged at the same height as the support and on either side of the support.

8. - Glass printing device (101) 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. - Glass printing device (1; 101) according to any one of claims 1 to 8, characterized in that it further comprises at least one additional print head (27) and means for changing (28) the at least one print head (22) 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. Glass printing machine (29), characterized in that it comprises, arranged successively: 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 a glass printing device according to any one of claims 1 to 9; a drying station (35); a control station (36); an unloading station (37); and two adjacent stations being connected by glass conveying devices, preferably rollers or a conveyor belt.

11. - Glass printing machine (29) according to claim 10, characterized in that it further comprises a post-processing station (PT) between the drying station (35) and the control station (36).

12. - A method for printing on glass employing a glass printing device (1; 101) according to any one of claims 1 to 9, characterized in that it comprises: loading onto the support (2) a glass (V) on at least one surface (S) of which an impression is to be made; making an impression on the surface (S) of the glass (V); unloading the printed glass (V).

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