EP2174786A1 - Screen printing machine and method - Google Patents

Abstract

The machine (2) has a disk shaped rotary object transporting plate (6) transporting objects (18, 20) and mobile with respect to a support frame (4). An object support (22) supports the objects carried by the plate. A printing post (10) uniquely prints one of the objects, and another printing post (12) uniquely prints the other object. A plate displacement unit displaces the object support between the printing posts after printing the former object at the former printing post and the latter object at the latter printing post. An independent claim is also included for a screen printing method for objects to be printed.

Description

The invention relates to a machine and a method for silk screen printing of flat objects, such as compact discs, telephone cards or solar cells.

Such printing machines are mounted in a production line that extends linearly. Objects are moved from one workstation to another by conveyors. The workstations perform various operations of manufacturing, printing and packaging objects.

For these assembly lines, it is desirable to produce printing machines having a high speed and a small footprint.

In particular, it is desirable to increase the print rate of objects by two.

For this purpose, it is known a printing machine having a printing station suitable for printing two objects at the same time.

This printing machine comprises a circular plate driven in rotation with respect to a support frame. The circular plate carries object holders on which two objects to be printed are arranged. The printing station is mounted around the circular plate.

The screen printing screen of the printing station is able to cover the two objects to be printed. He has two reasons to print. When moving a same squeegee of the printing station is adapted to apply the first pattern on the first object and the second pattern on the second object.

However, in this type of printing machine, the objects to be printed must be positioned on the support of objects with great precision, the relative position of one object with respect to the other must be identical when depositing each pair of objects since the relative position of one pattern relative to the other can not be changed.

The present invention aims to provide a printing machine having a high rate for a small footprint and allowing high printing accuracy.

• un bâti de support;
• un plateau de transport des objets mobile par rapport au bâti ;
• des postes de travail fixés au bâti le long du pourtour du plateau de transport, les postes de travail comprenant un premier poste d'impression ;
• des moyens de déplacement du plateau de transport pour amener les objets au droit des postes de travail;
• au moins un support d'objets porté par le plateau de transport, ledit support d'objets étant propre à porter un premier et un second objets ;

caractérisée en ce que les postes de travail comportent un second poste d'impression, le premier poste d'impression étant propre à imprimer uniquement le premier objet, le second poste d'impression étant propre à imprimer uniquement le second objet ; et en ce que des moyens de déplacement du plateau de transport sont aptes à déplacer le support d'objets entre le premier et le second postes d'impression après impression du premier objet au premier poste d'impression et impression du second objet au second poste d'impression.For this purpose, the subject of the invention is a screen printing machine for printing an object, the machine comprising:

• a support frame;
• a transport tray movable objects relative to the frame;
• workstations fixed to the frame along the periphery of the transport tray, the workstations comprising a first printing station;
• means for moving the transport tray to bring the objects to the right of the workstations;
• at least one object carrier carried by the transport tray, said object carrier being adapted to carry first and second objects;

characterized in that the workstations comprise a second printing station, the first printing station being adapted to print only the first object, the second printing station being able to print only the second object; and in that means for moving the transport tray are able to move the object carrier between the first and the second printing station after printing the first object at the first printing station and printing the second object at the second station printing.

• le plateau de transport est un plateau circulaire rotatif autour de son centre (A), et chaque poste d'impression comprend:
  • une plateforme fixée au bâti;
  • un écran de sérigraphie sur lequel un motif à imprimer est posé;
  • un support d'écran porté par la plateforme;
  • au moins une racle portée par la plateforme, la racle étant propre à presser le maillage de l'écran pour appliquer le motif à imprimer sur l'objet ;
  • des moyens de déplacement de la racle portés par la plateforme, la racle étant déplacée le long d'une course prédéfinie, la distance entre le centre du plateau de transport et la droite perpendiculaire à la course et passant par le milieu de cette course, présente une longueur non nulle,
• ladite distance présente une longueur au moins égale à la moitié de la longueur de la course de la racle,
• un même motif est posé sur l'écran de sérigraphie du premier poste d'impression et sur l'écran de sérigraphie du second poste d'impression,
• chaque poste d'impression comporte des moyens de réglage de la position du support d'écran propre à déplacer le support d'écran dans une plage de déplacement, et la plage de déplacement du support d'écran du premier poste d'impression couvre une zone du support d'objets différente de la zone couverte par la plage de déplacement du support d'écran du second poste d'impression,
• les moyens de réglage du premier poste d'impression sont distincts et indépendants des moyens de réglage du second poste d'impression.
• la machine d'impression comporte :
  • au moins une caméra de visualisation portée par le bâti, ladite caméra étant apte à visualiser le premier et le second objets posés sur le support d'objets;
  • une unité de commande propre à déterminer la position du premier et du second objets,
  ladite unité de commande étant apte à commander les moyens de réglage du premier poste d'impression indépendamment de la position du support d'écran du second poste d'impression,
• la machine comporte un premier et un second postes de séchage fixés au bâti le long du pourtour du plateau de transport, le premier et le second postes de séchage étant disposés après le premier et respectivement le second postes d'impression, en considérant le sens de déplacement du plateau de transport ; le premier et le second postes d'impression étant aptes à imprimer chacun deux fois le motif à imprimer sur le premier et respectivement le second objets.

According to particular embodiments:

• the transport tray is a rotating circular tray around its center (A), and each printing station comprises:
  • a platform fixed to the frame;
  • a silkscreen screen on which a pattern to be printed is placed;
  • a screen support carried by the platform;
  • at least one squeegee carried by the platform, the squeegee being able to press the mesh of the screen to apply the pattern to be printed on the object;
  • means for moving the squeegee carried by the platform, the squeegee being moved along a predefined stroke, the distance between the center of the transport tray and the straight line perpendicular to the race and passing through the middle of this race, present a non-zero length,
• said distance has a length at least equal to half the length of the stroke of the doctor blade,
• a same pattern is placed on the screen of the first printing station and on the screen of the second printing station,
• each printing station comprises means for adjusting the position of the screen support adapted to move the screen support in a movement range, and the range of movement of the screen support of the first printing station covers a area of the object carrier different from the area covered by the range of movement of the screen support of the second printing station,
• the adjustment means of the first printing station are distinct and independent of the adjustment means of the second printing station.
• the printing machine comprises:
  • at least one viewing camera carried by the frame, said camera being able to display the first and the second objects placed on the support of objects;
  • a control unit capable of determining the position of the first and second objects,
  said control unit being adapted to control the adjustment means of the first printing station independently of the position of the screen support of the second printing station,
• the machine comprises a first and a second drying station fixed to the frame along the periphery of the transport tray, the first and the second drying stations being arranged after the first and second printing stations respectively, considering the direction of moving the transport tray; the first and second printing stations being able to print each twice the pattern to be printed on the first and second objects respectively.

• déplacement d'un plateau de transport par rapport à un bâti de support pour amener un premier objet au droit d'un premier poste d'impression, le premier poste d'impression étant fixé au bâti le long du pourtour du plateau de transport, un premier et un second objets étant portés par un même support d'objets porté par le plateau de transport ;
• impression uniquement du premier objet au premier poste d'impression;
• déplacement du plateau de transport pour amener le second objet au droit d'un second poste d'impression, le second poste d'impression étant fixé au bâti le long du pourtour du plateau de transport; et
• impression uniquement du second objet au second poste d'impression.

The invention also relates to a screen printing process for printing objects which comprises the following steps:

• moving a transport tray relative to a support frame to bring a first object to the right of a first printing station, the first printing station being fixed to the frame along the periphery of the transport tray, a first and second objects being carried by the same object carrier carried by the transport tray;
• printing only the first object to the first printing station;
• moving the transport tray to bring the second object to the right of a second printing station, the second printing station being fixed to the frame along the periphery of the transport tray; and
• printing only the second object to the second printing station.

• la figure 1 est une vue en perspective de la machine d'impression selon l'invention ;
• la figure 2 est une vue de dessus d'une partie de la machine d'impression au dessus du plan B-B' représenté sur la figure 1, et des convoyeurs d'amenée et d'évacuation des objets à imprimer ;
• la figure 3 est un diagramme illustrant les étapes du procédé d'impression selon l'invention.

The invention will be better understood on reading the description which follows, given purely by way of indication and with reference to the appended drawings, in which:

• the figure 1 is a perspective view of the printing machine according to the invention;
• the figure 2 is a top view of a portion of the printing machine above the plane BB 'shown in FIG. figure 1 , and conveyors for feeding and evacuating objects to be printed;
• the figure 3 is a diagram illustrating the steps of the printing method according to the invention.

With reference to the figure 1 , the printing machine 2 according to the invention comprises a frame 4 supporting a disc-shaped tray 6, sequential drive means 7 rotating the tray 6 relative to the frame 4, and five processing stations 8, 10 , 12, 14, 16.

The drive means 7 are adapted to rotate the transport tray 6 by an angle of 2π / the number of object support, that is to say in the example of the invention described, a angle of π / 3.

The turntable 6 moves a first 18 and a second 20 objects to be printed from one processing station to another.

It carries six object supports 22 adapted to carry and hold in position the objects 18, 20.

Such object holder 22 is described in the patent application filed under the number FR 08 54198 in the name of the plaintiff.

The rectangularly shaped object supports 22 are located on the turntable 6 so that two of their sides are parallel to a tangent to the transport tray 6. They are regularly spaced angularly, so that an angle of 60 ° separates them two by two.

Each object support 22 is also able to transfer the objects 18, 20 of a supply conveyor 24 shown only on the figure 2 to the transport tray 6 and the tray 6 to an evacuation conveyor 25.

The supply conveyor 24 is capable of bringing two objects to be printed near the object support 22, 20, arranged side by side, conveyor belt held between two parallel motorized rollers.

The objects 18, 20 are placed on the object carrier 22 side by side, one side of the objects 18, 20 extending parallel to the wide side of the object carrier 22.

The object supports 22 are able to transport the objects to the evacuation conveyor 25 when they have been correctly printed.

The evacuation conveyor 25 is identical to the supply conveyor 24.

The treatment stations 8, 10, 12, 14, 16 are arranged at the periphery of the transport tray 6 at the right of each object support 22. They comprise a location station 8 for the position of the objects 18, 20 a first 10 and a second 12 printing stations, a control station 14 of print quality printed objects, and finally a station 16 discharge damaged or improperly printed objects.

The location station 8 has two cameras 26, 28 each for displaying a portion of the object carrier 22 on which an object to be printed 18, 20 has been placed.

The control station 14 comprises control cameras 38, 40 able to display the objects 18, 20 after printing.

The waste discharge station 16 comprises a storage container 44 damaged objects after printing.

The first printing station 10 includes with reference to the figure 1 a platform 46 fixed by a frame 48 to the frame 4.

The platform 46 carries a support 50 of a screen printing screen 52, and means 54 for adjusting the position of the screen support 50 in a radial direction to the turntable 6 and a direction perpendicular to said radial direction.

The adjustment means 54 are able to move the screen support 50 over an amplitude of a few millimeters to adjust the position of the screen 52 according to the position of each object 18, 20. Indeed, when the objects are transferred from the supply conveyor 24 to the object support 22, they are positioned with an accuracy of a few millimeters.

The range of motion of the screen support 50 of the second print station 12 covers an area of the object carrier 22 different from the area covered by the range of motion of the screen carrier 50 of the first print station.

In particular, the range of displacement of the screen support 50 of the first printing station 10 covers an area on which the first object 18 is able to be positioned, while the range of movement of the screen support 50 of the second printing station covers an area of the object support 22 capable of receiving the second object 20.

The platform 46 also carries a squeegee and counter-squeegee system 56 able to move vertically under the action of a jack, and a carriage 58 supporting the squeegees and the jack. The carriage 58 is guided on a support beam 60 fixed on the platform 46 and extending in parallel to the tangent to the plate 6.

The squeegee and counter-squeegee system 56 is capable of pressing the mesh of the screen 52 to apply a first pattern 62 to the first object 18.

The doctor blade and the counter-doctor blade 56 are moved by the carriage 58 along a predefined stroke C which is parallel to a tangent to the transport tray 6.

The length of the stroke C is approximately equal to the length of the pattern to be printed.

• α = C/2R où C est la longueur de la course de déplacement de la racle et R est le rayon du plateau 6.

The first printing station 10 is angularly spaced from the location station 8 by an angle equal to π / 6 - α, the angle α being defined as follows:

• α = C / 2R where C is the length of the stroke of movement of the doctor blade and R is the radius of the plate 6.

Consequently, and taking into account the fact that the plate is sequentially driven by an angle of π / 3, the first printing station 10 is offset relative to the object support 22 so as to be centered, not between the first 18 and second 20 objects, but in the center of the first object 18.

In other words, considering a straight line D perpendicular to the stroke C of the doctor blade passing through the middle M of said stroke, this straight line D does not pass through the center A of the transport plate 6.

In particular, the minimum distance d between the center of the plate 6 and the line D is equal to half the length of the stroke C of the doctor blade 56. $$\mathrm{d}\mathrm{=}\min \left\{\left|\mathrm{AT}\mathrm{x}\right|\mathrm{,}\mathrm{with\; x}\mathrm{\in }\mathrm{D}\right\}$$

The second printing station 12 is identical to the first printing station 10.

The second pattern 64 placed on the silk-screen screen 52 of the second printing station 12 is identical to the pattern 62 placed on the screen-printing screen 52 of the first printing station 10.

Similarly, the second printing station 12 is angularly spaced from the control station 14 by an angle of π / 6 -α.

Thus, the first 10 and the second 12 printing stations are angularly spaced by an angle of π / 6-2α.

The printing machine 2 further comprises a control unit 66 able to receive the images filmed by the cameras 26, 28 and to determine from these images the position of the first 18 and the second 20 objects.

The control unit 66 is able to control the adjustment means 54 of the screen support 50 of the first printing station 10 to position the screen support 50 so as to have the first print pattern 62 at the right of the first object 18.

Similarly and independently, the control unit 66 controls the moving means 54 of the second printing station 12 to arrange the second print pattern 64 to the right of the second object 20.

In operation, during a step 100, the objects to be printed 18, 20 are brought by the supply conveyor 32 near the location station 8.

The objects 18, 20 are moved from the supply conveyor 24 to the object support 22 of the location station 8.

During a step 102, the cameras 26, 28 visualize the location of the objects 18, 20 and transmit the images thus filmed to the control unit 66.

The control unit 66 determines, by software means, the position of the objects 18, 20 and transmits to the adjustment means 54 commands for moving the screen support 52 of the first printing station 10 and different commands to the adjustment means. 54 of the second printing station 12.

During a step 104, the drive means 7 rotate the circular plate 6 by an angle of π / 3, that is to say an angle of 60 °.

In a step 106, the squeegee and squeegee system 56 is moved to apply the first print pattern 62 to the first object 18. In this step, the second object 20 is not printed.

During a step 108, the drive means 7 rotate the transport tray 6 by an angle of π / 3.

In a step 110, the squeegee and counter-squeege system 56 of the second print station 12 is moved to apply the second print pattern 64 to the second object 20.

The first object 18 is not printed during this step.

During a step 112, the transport tray 6 is moved by an angle of π / 3 to bring the object carrier 22 to the control station 14. The control cameras 38, 40 film the first 18 and respectively the second object and transmit these images to the control unit 66.

The control unit 66 determines whether these objects 18, 20 are broken or damaged.

When these objects are not broken or damaged, the object support 22 is controlled to transfer the objects 18, 20 to the evacuation conveyor 27.

If these objects are damaged, the control unit 66 controls the object carrier 22 so that it transfers these objects into the storage container 44 of the scrap discharge station 16 when the transport tray 6 has been driven into position. rotation of an angle of π / 3.

As a variant, the plate 6 comprises ten object supports 22 and the printing machine comprises a tracking station followed in the order of rotation of the plate, a first printing station, a first drying station , a second printing station, a second drying station and finally a control station and unloading objects.

As for the first embodiment of the invention, the object carrier 22 is adapted to carry two objects to be printed. The first printing station is able to print only the first object and the second printing station is able to print only the second object.

The printing machine according to this variant of the invention is used when it is desired to print the same pattern twice on the same object. In this case, the loading of the transport tray 6 is carried out sequentially after two turns of the tray. The use of a drying station makes it possible to print the same object a second time with the same printing station, the object having not moved from its support of objects between two impressions.

This variant is particularly interesting when printing solar cells. Indeed, a double impression of a pattern on a solar cell makes it possible to increase the thickness of the lines intended to capture the current of the cell and thus to increase the energy efficiency of the solar cell thus constituted.

Claims (9)

Printing machine (2) by screen printing of object to be printed (18, 20), the machine (2) comprising: - a support frame (4); - a tray (6) for transporting objects (18, 20) movable relative to the frame (4); - work stations (8, 10, 12, 14, 16) fixed to the frame (4) along the periphery of the transport tray (6), the work stations (8, 10, 12, 14, 16) comprising a first printing station (10); means (7) for moving the transport tray (6) to bring the objects (18, 20) to the right of the work stations (8, 10, 12, 14, 16); at least one object carrier (22) carried by the transport tray (6), said object carrier (22) being adapted to carry a first (18) and a second (20) object so as to present them jointly with each workstation; characterized in that the workstations (8, 10, 12, 14, 16) comprise a second printing station (12), the first printing station (10) being adapted to print only the first object (18) the second printing station (12) being adapted to print only the second object (20); and in that the means (7) for moving the transport tray (6) are able to move the object carrier (22) between the first (10) and second (12) printing stations after printing the first object (18) at the first printing station (10) and printing the second object (20) at the second printing station (12). The printing machine (2) according to claim 1, wherein the transport tray (6) is a circular tray rotatable about its center (A), and wherein each printing station (10, 12) comprises: - a platform (46) fixed to the frame (4); - a screen screen (52) on which a pattern to be printed (62, 64) is placed; - a screen support (50) carried by the platform (46); - at least one squeegee (56) carried by the platform (46), the squeegee (56) being able to press the mesh of the screen (52) to apply the pattern to be printed (62, 64) on the object ( 18, 20); - means (58, 60) for moving the doctor blade (56) carried by the platform (46), the doctor blade (56) being moved along a predefined stroke (C), the distance (d) between the center (A) the transport tray (6) and the straight line (D) perpendicular to the stroke (C) and passing through the middle (M) of this race (C) has a non-zero length. Printing machine (2) according to claim 2, wherein said distance (d) has a length at least equal to half the length of the stroke (C) of the doctor blade. Printing machine (2) according to claim 2 or 3, wherein the same pattern (62, 64) is placed on the screen (52) of the first printing station (10) and on the screen. screen printing (52) of the second printing station (12). Printing machine (2) according to any one of claims 2 to 4, wherein each printing station (10, 12) comprises means (54) for adjusting the position of the clean screen support (50) moving the display support (50) in a moving range, and
wherein the range of motion of the display medium (50) of the first print station (10) covers an area of the object carrier (22) different from the area covered by the range of motion of the display medium ( 50) of the second printing station (12). Printing machine (2) according to claim 5, wherein the adjustment means (54) of the first printing station (10) are distinct and independent of the adjustment means (54) of the second printing station (12) . Printing machine (2) according to any one of claims 1 to 6, which comprises: at least one viewing camera (26, 28) carried by the frame (4), said camera (26, 28) being able to display the first (18) and the second (20) objects placed on the support of objects (22); a control unit (66) able to determine the position of the first (18) and second (20) objects, said control unit (66) being adapted to control the adjustment means (54) of the first printing station (10) independently of the position of the display support (50) of the second printing station (12). Printing machine (2) according to any of claims 1 to 7, which comprises a first and a second drying station fixed to the frame (4) along the periphery of the transport tray (6), the first and the second second drying stations being arranged after the first (10) and respectively the second (12) printing stations, considering the direction of movement of the transport tray (6); the first (10) and the second (12) printing stations being able to print each twice the pattern to be printed (62, 64) on the first (18) and the second (20) objects respectively. A method of screen printing printed objects (18, 20), characterized in that the method comprises the following steps: - moving (104) a transport tray (6) relative to a support frame (4) to bring a first object (18) to the right of a first printing station (10), the first station impression (10) being fixed to the frame (4) along the periphery of the transport tray (6), a first (18) and a second (20) object being carried by the same object carrier (22) carried by the transport tray (6); printing (106) only the first object (18) at the first printing station (10); - moving (108) the transport tray to bring the second object (20) to the right of a second printing station (12), the second printing station (12) being fixed to the frame (4) along the around the transport tray (6); and printing (110) only the second object (2) to the second printing station (12).

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