Patent Application
20190270299
This application claims priority of French Patent Application No. 18 51871 filed on Mar. 5, 2018.
The present invention relates to printing machines.
Printing stations, especially those with inkjet print heads, require very precise positioning of the object to be printed. In fact, the underside of the inkjet print heads includes rows of nozzles, wherein the nozzles are, for example, spaced apart from each other by 0.07105 mm in the same row. However, it has sometimes been found in machines of the type described above that the quality of the positioning of the objects with respect to the printing station is inadequate, which can lead to a decrease in the quality of the printing.
In addition, in these machines, each object carrier is associated with a rotating actuator, so that the object rotates below the printing station. Such machines, therefore, have a large number of actuators, which has a negative impact on the cost. In addition, each of these actuators must be set in order to obtain the desired movement of the object below the printing station. The settings are quite long and tedious.
There is thus a need to overcome all or some of the above disadvantages by providing a less expensive printing machine and/or allowing improved print quality.
An object of the invention is, therefore, to overcome all or some of the above disadvantages by providing a less expensive printing machine and/or allowing improved print quality.
For this purpose, the present invention relates to a printing machine for printing a plurality of objects, wherein the printing machine includes:
The drive system includes:
According to particular embodiments, the printing machine includes one or more of the following features, taken in isolation or in any technically feasible combination:
The invention also relates to an assembly of a printing machine as described above and the plurality of objects to be printed.
Finally, the invention relates to a printing method for printing a plurality of objects, wherein the method includes the following steps:
The invention will be better understood upon reading the description which follows, given solely by way of example and with reference to the appended drawings, wherein:
An assembly 1 according to the invention is described with reference to
The assembly 1 includes a plurality of objects 5 to be printed, and a printing machine 10 for printing the objects.
The objects 5 are analogous to each other. Each object 5 is, for example, substantially of revolution about an object axis Δ. Each object 5 is, for example, a tube, but may be a bottle, a beaker or a cup.
The objects 5, for example, have a cylindrical or frustoconical outer surface.
The printing machine 10 includes a frame 12, a turret 14 that is rotatably mounted and indexed relative to the frame about an axis of rotation Δ1, and a plurality of object carriers 16 designed to carry the objects. The printing machine 10 further includes, in the example shown, a loading station 18, a pre-processing station 20, a printing station 22, and a post-processing station 24, wherein all of these stations are advantageously angularly distributed around the axis of rotation Δ1. Finally, the printing machine 10 includes a drive system 26 that is designed to drive one of the object carriers 16 in rotation with respect to the turret 14.
The frame 12 includes a gantry 28 on which the pre-processing station 20, the printing station 22 and the post-processing station 24 are fixed. In the example shown, the frame 12 also includes a turret support 30 mounted on the gantry 28 to rotate about an axis of inclination Δ2. Finally, the frame 12 includes a support 32 forming a seat on which the drive system 26 is mounted.
The gantry 28, for example, has an inverted “U” shape.
The turret support 30 advantageously forms a cradle located below the processing stations. The turret support 30 is designed to adjust the inclination of the turret 14 relative to the horizontal about the axis of inclination Δ2.
The support 32 is, for example, fixed on the support of the turret 30.
The pre-processing station 20 is designed, for example, to perform plasma pre-processing of the surface of the objects 5 to be printed.
The printing station 22, for example, includes print heads 34 that are designed to project ink jets onto one of the facing objects 5. The ink jets are, for example, vertical.
The print heads are, for example, of the piezoelectric type and can print a pattern (not shown) on the objects 5, for example using a four-color process.
The post-processing station 24 is advantageously designed to carry out the drying of the ink deposited on the objects 5, for example using UV (ultraviolet) rays.
The object carriers 16, four in number in the example, are respectively rotatably mounted on the turret 14 about the object carrying axes D1, D2, D3, D4. The object carriers 16 are regularly spaced at 90° about the axis of rotation Δ1 of the turret 14.
The turret 14 is rotatable about the axis of rotation Δ1 between a successive plurality of positions, four in number in the example, relative to the frame 12. In each of these positions of the turret 14, one of the object carriers 16 allows the loading or unloading of one of the objects 5, another of the object carriers 16 holds one of the objects 5 opposite the pre-processing station 20, another of the object carriers 16 holds one of the objects 5 opposite the printing station 22, and finally the last of the object carriers 16 holds one of the objects 5 at the post-processing station 24.
Each of the object carriers 16 further respectively defines a circular drive track 36 about the object carrier axes D1-D4. The object carrier axes D1-D4 respectively merge with the object axes A of the objects they carry.
In the example shown, the object carrier axes D1 to D4 are horizontal. The object carrier axes D2 and D4 are substantially coincidental and parallel to the axis of inclination Δ2. The object carrier axes D1 and D3 are substantially coincidental and perpendicular to the object carrier axes D2 and D4.
According to a variant not shown, the turret 14 has a different number of object carriers, for example two, six, eight or more.
In a particular embodiment the turret 14 and the object carriers 16 may be devoid of any system capable of rotating the objects 5 on themselves.
As may be seen in
The first part 38 is, for example, a square.
The second part 40 includes a locking device 44 and a drive device 46.
The second part 40 is movable between an active position, shown in
In the active position, the drive device 46 is designed to rotate the object carrier 16 opposite the printing station 22, and the locking device 44 is designed to lock the turret 14 in rotation relative to the frame 12 in one of the previously mentioned positions of the turret.
In the rest position, the drive device 46 is away from the object carrier 16 in question, and the locking device 44 is also away from the turret 14.
The second part 40 is, for example, mounted on the first part 38 by slides 48.
The second part 40, for example, includes a plate 50 on which the locking device 44 and the drive device 46 are mounted.
In particular, the locking device 44 is not a device for rotating the turret 14.
Advantageously, the locking device 44 makes it possible to lock the turret 14 in its successive angular positions around the axis of rotation Δ1 with a positioning accuracy of the objects 5 under the print heads 34 that is greater than 0.1 mm in the circumferential direction about the axis of rotation Δ1.
In the example shown, the locking device 44 includes a finger 52 designed to be received in notches 54 of the turret 14 (one of which is shown in
The notches 54 are here four in number and are advantageously evenly distributed on a lower face of the turret 14 about the axis of rotation Δ1.
According to a variant not shown, the locking device 44 forms a notch and the turret 14 has fingers, wherein the notch is designed to receive one of the fingers in the active position. In the example, there would therefore be four fingers corresponding to the four positions of the turret 14.
According to other variants not shown, the locking system takes other forms known in themselves to those skilled in the art.
The drive device 46 includes, in the example shown, a belt 56 that is designed to be in contact in the active position with the drive track 36 of the object carrier 16 located opposite the printing station 22, and to drive this object carrier. The drive device 46 also includes an actuator 58 to move the belt 56 by means of a pulley 60 that is advantageously toothed, and includes two pulleys 62, 64 that are rotatably mounted on the plate 50 in order to tension and guide the belt 56.
The pulley 60 is designed to be driven by the actuator 58 in rotation with respect to the plate 50.
The two pulleys 62, 64 define between them an active segment 66 (
The track 36 of the object carrier 16 is also advantageously toothed.
The actuator 42, for example, includes a connecting plate 39 fixed on the support 32, and a jack 68 fixed on the connecting plate and on the plate 50.
The jack 68 is, for example, pneumatic.
According to a variant not shown, the jack 68 is electric. It then includes a servomotor controlling a screw which translates a nut that is integral with the plate 50. This allows the print rate to be increased by advantageously combining the rotational movement of the turret 14 with the translational movement of the second part 40 along the axis Δ3.
The direction of translation Δ3 is advantageously substantially parallel to the axis of rotation Δ1 of the turret 14.
The active segment 66 shown in
As may be seen in
The operation of the assembly 1 is deduced from its structure and will now be described to illustrate a method according to the invention.
When the machine 10 is in operation, one of the objects already printed is removed from its carrier 16 at the loading station 18 shown in the background of
The turret 14 is then moved to its next position by a rotation about the axis of rotation Δ1. This brings the newly-loaded object 5 to the pre-processing station 20, which pre-processes the object using plasma.
At the same time, another of the objects 5 is located below the printing station 22, and another object 5 is located at the post-processing station 24. Each of the movements of the turret 14 from one of its positions to the next position moves the loaded objects 5 from one processing station to the next station.
Before the arrival of one of the objects 5 below the printing station 22, the drive system 26 is in the rest position. There is then no rotational drive of the object carrier 16 in question, and the turret 14 is simply positioned relative to the processing stations.
When the concerned object carrier 16 arrives to face the printing station 22, the turret 14 is immobilized and the jack 68 passes the second part 40 from the rest position to the active position. During its movements, the plate 50 slides relative to the first part 38 in the direction of translation Δ3. In the example shown, the second part 40 rises relative to the frame 12.
This has a double effect. On the one hand, the locking device 44, which was away from the turret 14, approaches the turret and the finger 52 is received in one of the notches 54, in order to immobilize the turret in an angular position relative to the axis of rotation Δ1 that is perfect for obtaining good printing on the object 5 located facing the printing station 22.
On the other hand, this passage to the active position brings the active segment 66 of the belt 56 into contact with the drive track 36 of the object carrier 16 located opposite the printing station 22. The movement of the belt 56 obtained by means of the actuator 58 then drives the object carrier 16 in rotation about the object carrier axis D3. This has the effect of rotating the object 5 about its object carrier axis Δ.
The movements of the belt 56 are controlled very accurately by the actuator 58. Advantageously, the toothed structure of the belt 56 described above allows very precise transmission of the movements of the belt 56 to the object carrier 16 by meshing. The rotation of the object 5 below the print heads 34 is thus very precisely controlled.
When printing is complete, the second part 40 is returned to the rest position by the jack 68. The belt 56 is then no longer in contact with the drive track 36. The finger 52 of the locking device 44 comes out of the notch 54 and the turret 14 is again free to rotate.
The turret 14 then moves to the next angular position. The object 5 that has just been printed then arrives at the level of the post-processing station 24.
The above steps are repeated cyclically, so that each of the objects 5 is successively loaded, pre-processed, then printed, post-processed, and finally unloaded.
Depending on the shape of the object 5, it is possible to tilt the turret 14 relative to the inclination axis Δ2 so that an upper generatrix of the surface of the objects 5 to be printed is advantageously substantially horizontal at the printing station 22.
With the features described above, the printing machine 10 is less expensive and allows for improved print quality.
In particular, thanks to the locking device 44, the turret 14 is very precisely immobilized in the desired angular positions with respect to the axis of rotation Δ1. The locking device 44 makes it possible to position the object very precisely below the printing station 22. In addition, there is only one rotary drive device and it is capable of acting on any of the object carriers 16 as soon as the object carrier is opposite the printing station 22. In addition, the same actuator 42 makes it possible to obtain both precise angular locking of the turret 14 and the activation of the drive device 46.
| Number | Date | Country | Kind |
|---|---|---|---|
| 18 51871 | Mar 2018 | FR | national |
