Apparatus and method for applying paint with roller coaters, preferably to photovoltaic panels

Abstract

A bridge device for measuring the thickness of mainly flat panels to be placed in a panel production line includes a frame having feet for fixing the bridge device to the floor; a plurality of supports that support measuring contact systems, which are slidable perpendicularly to the conveying direction of the panels so to adjust their positions for a transversal measure of the panels; a plurality of measuring contact systems, of which is one is for each longitudinal side of the panels; a photocell detecting the position of the panels and their lengths; blocking knobs for blocking the supports; and a device transmitting the information concerning the actual thickness of each panel to a machine for treating one of the main surfaces of the panel.

Claims

1. A bridge device for measuring a thickness of mainly flat panels to be placed in a production line for producing the panels, the production line comprising a plurality of machines placed in series, the bridge device comprising: a frame provided with feet for fixing the bridge device to a floor; a plurality of supports supporting measuring contact systems, the supports being slidable in a direction perpendicular to a conveying direction of panels so as to be adjustable for a transversal measuring of the panels; a plurality of measuring systems, one for each panel's longitudinal side parallel to the conveying direction of panels; a photocell detecting a position of the panel and a length thereof; a plurality of blocking knobs for blocking the supports; and a transmitting device transmitting information on an actual thickness of each panel to a machine for treating a surface of the panel.

2. The bridge device according to claim 1, wherein the bridge device is provided in combination with the production line for producing the panels, the production line comprising the machine working on the surface of the panels, the machine being a roller coater for applying paint, a machine for cleaning the surface of the panel, or a sanding machine.

3. The bridge device according to claim 2, wherein the bridge device is provided in combination with the production line for producing the panels, the production line comprising a roller coater for applying paint to the mainly flat panels.

4. The bridge device according to claim 3, wherein the roller is provided with a PLC adjusting a position of an application head of the roller coater according to the thickness measured by the bridge device.

5. The bridge device according to claim 4, wherein the measuring systems are divided into two parts, of which one is placed over an upper surface and another under a lower surface of the panels.

6. The bridge device according to claim 5, wherein each measuring system is divided into a plurality of parts of which one is placed one over and another one under the panel, each part being provided with a pneumatic cylinder that is integral with an encoder detecting a displacement by leaning on the panel with an idle roller.

7. The bridge device according to claim 3, wherein the mainly flat panels are glass panes.

8. The bridge device according to claim 7, wherein the glass panes are photovoltaic panels.

9. A method of measuring a thickness of panels in a production line for producing the panels using a bridge device according to claim 6, the method comprising the following steps: (a) intercepting the panel conveyed in the production line using the photocell, which activate the measuring systems; (b) when the panel detected by the photocell reaches the plurality of measuring systems, detecting, by difference, a value measured by the pneumatic cylinders carrying the idle rollers in contact with the upper and lower surfaces of the panel; (c) sending the measured value to the PLC of a machine treating the panel; (d) adjusting at least one portion of the machine treating the panel according to an actual thickness of the panel; and (e) when the photocell detects an end of the panel, sending a signal to the measuring systems, which deactivate.

10. A method of measuring a thickness of panels in a production line for producing the panels using a bridge device according to claim 6, wherein the machine is a roller coater for applying paint to glass panes adapted for use as photovoltaic panels, the method comprising the following steps: (a) intercepting a glass pane conveyed in the production line with the photocell, which activates the measuring systems; (b) when the glass pane detected by the photocell reaches the measuring systems, detecting, by difference, values measured by the pneumatic cylinder carrying the idle roller in contact with top and bottom surfaces of the panes; (c) sending the value to the PLC of the roller coater, the PLC managing a positioning of the applying roller; (d) positioning, through two independent motoring systems, each of two sides of the application head according to an actual thickness of the pane; and (e) when the photocell detects an end of the panel, sending a signal to the measuring systems, which deactivate.

11. The method according to claim 10, wherein the bridge device is placed upstream of a closed belt conveyor placed immediately upstream of the roller coater.

12. The method according to claim 10, wherein the bridge device is placed upstream of a closed belt conveyor at a distance from the roller coater.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Further advantages and properties of the present invention are disclosed in the following description, in which exemplary embodiments of the present invention are explained in detail on the basis of the drawings:

[0032] FIG. 1 is an axonometric view of the apparatus with cover;

[0033] FIG. 2 is an axonometric view of the apparatus, wherein a cover was removed, and applying roller in its working position;

[0034] FIG. 3 is a lateral view of the apparatus, wherein a cover was removed, and applying roller in the extraction position;

[0035] FIG. 4 is a lateral view of the apparatus without covers;

[0036] FIG. 5 is a lateral view of the supporting system for rollers;

[0037] FIG. 6 is a front view of the lifting system for the applying roller;

[0038] FIG. 7 is an axonometric view of a detail of the supporting system for the applying roller;

[0039] FIG. 8 is an axonometric view of the roller coater provided with a bridge device for measuring panels thickness;

[0040] FIG. 9 is axonometric view of the bridge device and a conveyor.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0041] It is worth remembering that, although the present description refers to the painting of glass panes, the description can be applied to the painting of panels made of any kind of material. When panels material is not transparent, optical sensors can be a good option.

[0042] It is also worth remembering that the roller coater indicated with the numeral 1 is generally a component of a more complex painting line, comprising other sundry (not shown) apparatuses placed upstream and downstream said roller coater 1. For example, upstream said apparatus 1 there can be provided apparatuses for the pre-treatment of panels, while downstream there can be provided further apparatuses for applying further paint layers and/or ovens for drying/polymerizing the applied paint.

[0043] FIG. 1 shows a roller coater 1 provided with the covers needed for its functioning without risk for human operators, as prescribed by the Machinery Directive 2006/42/CE. The bold arrow shows the conveying direction of the glass panes to be painted. In particular, the roller coater 1 is provided with a cover 2 that is to be removed in order to reach an applying roller 3. For safety reasons, the cover is screwed with two screws to said roller coater 1, screws that can be removed through an ordinary tool. Normally said roller coater 1 is provided with a PLC 27 having an interface that allows a human operator both to modify the set-up of the apparatus, and to detect the working parameters of said roller coater 1.

[0044] FIG. 2 shows the roller coater 1, wherein said cover 2 was removed and the applying roller 3 in its working position. Said vertical cover 2 covers the applying roller 3. A horizontal cover 6 covers both the applying roller 3 and a dosing roller 11 (visible in FIG. 4). Said applying roller 3 and said dosing roller 11 form an application head.

[0045] The dosing roller 11 rotates in the conveying direction of the glass pane 8 (visible in FIG. 8). The applying roller 3 is a reverse roller, i.e., rotates in the opposite direction with respect to the conveying of the panes to be painted, and would tend to repel the glass pane, i.e., send it back to its place of origin.

[0046] In order to prevent this, in the art using a feed roller 9 is known (visible in FIG. 4), which rotates according to the conveying direction of the panes, and therefore provides for the conveying of the glass pane 8. A further cover 5 covers said feed roller 9.

[0047] It is worth mentioning that the interaxis between said feed roller 9 and the applying roller 3 must be shorter than the minimum length of the shortest glass panel that can be coated in said roller coater. In this case, the distance is 600 mm.

[0048] FIG. 3 shows a lateral view of said roller coater 1, while said applying roller 3 is extracted through two straps 4, each placed at one of its two ends. Said straps 4 are part of a lifting member, suitable for the weight of said roller 3, which is around 200 kg. Said lifting member can be a bridge crane or a stacker, placed in a suitable point; the lifting member is independent from said roller coater 1. Said lifting member is used also for inserting a new applying roller 3 into said roller coater 1, in order to replace said worn/damaged roller 3. Obviously, the roller 3 can be replaced only when said roller coater is stopped (during downtimes).

[0049] The positions of the rollers and of the covers of the roller coater 1 must be such, that the applying roller 3 can be extracted without entering into contact with other mechanical parts of the coater 1.

[0050] The dosing roller 11 undergoes a markedly lesser wear with respect to the applying roller 3. When the dosing roller 11 must be replaced, the top cover 6 is removed, which opens like a door through a hinge 7 placed at the end of said cover 6 oriented to the entry of said panes.

[0051] FIG. 4 shows a lateral view of the roller coater 1, wherein the covers 2, 5 and 6 were removed. Said removal allows to observe the feed roller 9, which in use is hidden by said cover 5, the applying roller 3 and the dosing roller 11, which together form the application head, in use hidden by said cover 6. For comparison, the roller indicated with the numeral 3′ shows the position for the vertical extraction of said roller 3. In other words, the roller indicated with 3′ is in the extraction position shown in FIG. 3.

[0052] As customary in the art, the feed roller 9 rotates in the conveying direction of the glass panes, and is coupled to a contrast roller 39. The applying roller 3 is a reverse roller and rotates in the direction opposite to the conveying direction. The dosing roller 11 rotates in the conveying direction.

[0053] FIG. 4 allows to observe also a closed belt conveyor 12, which is a component of the roller coater 1. Said conveyor 12 is rectified; as customary, the closed belt rotates around two rollers, the first of which is an idle roller 31, while the second roller is a motorized roller 32.

[0054] As explained, the applying roller 3 is a reverse roller, i.e., tends to repel the glass pane 8, therefore there must be provided said feed roller 9, which forces the pane across the applying roller 3 and the contrast roller 33. The contrast roller 33 can be moved in the conveying direction, so that when it is moved from the vertical position with respect to the applying roller 3, a too violent contact with the entry edge of the glass pane 8 is prevented.

[0055] The conveying belt 12 is rectified in order to prevent surface bulging, due e.g., to a vulcanized joint, so as to prevent thickness differences along the belt. In fact, said differences in thickness provoke a difference of pressure of the applying roller 3, and therefore a difference in the thickness of applied paint.

[0056] The feed roller 9 presses on the glass pane 8 with an interference of about 0.5 mm. The glass pane 8 is intercepted by a photocell at the entry of the roller coater 1, which accompanies it until said pane is held between said applying roller 3 and contrast roller 33, with an interference of 0.5 mm again. The feed roller lifts from the glass pane 8 and the pane is dragged by the belt, in order to prevent vibrations during paint application.

[0057] FIG. 5 shows a lateral view wherein all the covers were removed, and the support systems of said rollers are shown. Said application head, comprising applying roller 3 and dosing roller 11, moves with respect to the conveying belt 12 through two independent systems 13 provided with ball recirculating runners, one system on the right side and one system on the left side. In this way, it can adjust to the actual dimensions of the thickness of the glass pane 8, which can be different on the two sides for some tenths of millimetre. The motorization is provided with brushless motors and encoder for the detection of position, with a centesimal precision.

[0058] The feed roller 9 is provided with a similar lifting system, but without independent adjustment to the thickness on its two sides.

[0059] As customary in roller coaters, the dosing of paint occurs through the pressure exerted by the dosing roller 11 on the applying roller 3; a stronger pressure decreases the quantity of applied paint. The speed of transport, too, affects the applied quantity in an unwanted way: in fact, a greater speed of the glass panes 8 generally causes an increase of the quantity of applied paint.

[0060] In roller coaters, typically the system for adjusting the quantity of applied paint occurs by varying the pressure applied to said dosing roller 11. On some roller coaters, the dosing roller rotates in reverse, i.e., opposite to the conveying direction, and this leads to a removing of paint from said roller, altering the adjustment of the dosing roller; both can influence the quantity of applied paint.

[0061] FIG. 6 shows the lifting member of the applying roller 3 for its replacement. As already explained, said lifting member can be a bridge crane or a stacker suitably placed above said roller coater 1. The lifting member is independent from said roller coater 1.

[0062] FIG. 7 shows a detail of the support for the applying roller 3. When in its working position, said applying roller 3 is held by suitable supports 15 that fix the ball bearings on which it rotates. When the applying roller 3 is replaced, said supports are unscrewed through screws 16 and said roller 3 slides, supported by suitable supports of the roller coater 1 in a position suitable for its lifting. In particular, FIG. 7 shows a bracket 14 which aims to prevent the fall of the roller 3 once its supports are removed.

[0063] FIG. 8 and FIG. 9 show the second embodiment of the present invention, in particular a bridge device 20 for measuring the thickness of glass panes 8. The two Figures show the preferred placement for the bridge device 20, i.e., upstream a closed belt conveying system 10 placed upstream said roller coater 1.

[0064] FIG. 8 shows a glass pane 8 that is inserted into the roller coater 1 through a closed belt conveyor 10 placed upstream said roller coater 1. The bold arrow shows the conveying direction of the glass panes 8.

[0065] Upstream said closed belt conveyor 10 there is provided a bridge device 20 according to the second embodiment of the present invention. Said bridge device allows to measure the thickness of glass panes 8 during their conveyance through said bridge device, so that the data are sent in real time to the roller coater 1, which adapts to the transmitted measures.

[0066] FIG. 9 shows an axonometric view of said bridge device 20, placed in proximity of the closed belt conveyor 10. The bold arrow shows the conveying direction of the glass panes 8.

[0067] Said bridge device 20 comprises:

[0068] A frame 21 provided with feet 22 for fixing it to the floor, so that the bridge device 20 is independent and can be placed in the most suitable points of the painting line. In this way, bumps and/or vibrations generated by the movement of the rotating organs are prevented, which might affect the precision of measuring;

[0069] Supports 23 supporting contact sensors; said supports can be slid in a direction which is perpendicular to the conveying direction of the panes 8 to be painted, in order to adapt their position to the transversal measure (width) of the glass pane 8;

[0070] Two contact measuring systems 24 (one for each side of the glass); said measuring systems 24 are divided into two parts, a top part and a bottom part with respect to the surface of the glass pane 8, and are both provided with a pneumatic cylinder, in its turn integral with an encoder detecting the displacement while leaning on the surface through an idle roller;

[0071] Transversal photocells 25, detecting the position of the glass pane 8 and its length;

[0072] Blocking knobs 26 for blocking said supports 23.

[0073] In fact, it is known that glass panes, especially when provided with a low thickness, are not provided with the same thickness on their right and left side, i.e., the sides parallel to the conveying direction of said panes 8. Said difference can be of some tenths of millimetre. As the application of paint on glasses, always destined to solar sector, is particularly delicate and requires an extreme precision, the working pressure of the applying roller 3 on the surface of the glass pane is very important for ensuring the uniformity of the paint layer.

[0074] Advantageously, the bridge device 20 is not a component of the roller coater 1 and is fixed to the floor, preventing problems due to vibrations of the roller coater 1 during measuring.

[0075] In this second embodiment, although the bridge device 20 is independent from the roller coater 1, nonetheless there is provided a communication system between the bridge device 20 and the PLC 27 of the roller coater 1, allowing to transmit the actual thickness data of each pane 8 to the application head of the roller coater 1 in real time.

[0076] Thanks to the use of the bridge device 20, the transversal position of the application head in the direction of width can be adjusted to the actual shape of the pane to be painted, in order to adapt it to the thickness difference between the two sides of the pane, using the above explained system with ball recirculating runners and brushless motor.

[0077] In short, the measuring of the thickness of glass panes 8 and the consequent painting of the glass panes 8 occurs as follows:

[0078] (a) The glass pane 8 conveyed in the painting line is intercepted by the photocells 25, activating the measuring systems 24;

[0079] (b) When the glass pane 8 detected by the photocells reaches the two measuring systems 24, said pneumatic cylinders bring said idle roller in contact with the top and bottom surfaces of the glass pane, and by value difference the actual thickness of the pane is measured;

[0080] (c) The measure is transmitted to the PLC 27 of the roller coater 1, which manages the positioning of the application head;

[0081] (d) Through two independent motorizations for positioning each of the two sides of the roller 3, said roller can be adjusted to the actual thickness of the glass pane, and with the working pressure optimal for a correct paint application on both sides;

[0082] (e) When the photocells 25 detect the end of the glass pane, they send a signal to the measuring systems 24, which deactivate.

[0083] The above description refers specifically to the use of said bridge device 20 for measuring the thickness of glass panes 8 inside a roller painting line for photovoltaic panels. The skilled man cannot miss the fact that any kind of mainly flat panel 8 can be painted in a line comprising the roller coater 1 according to the present invention, e.g., panels made of wood, plastics, fibrocement, etc. Similarly, the skilled man cannot miss the fact that the bridge device 20 according to the present invention can be used in a production line comprising machines of any type working in contact with a main surface of said panel 8, e.g., machines for cleaning said main surface, or sanding machines.

LIST OF REFERENCE NUMBERS

[0084] 1 roller coater [0085] 2 cover [0086] 3 applying roller [0087] 4 strap [0088] 5 cover for the feed roller [0089] 6 cover [0090] 7 hinge [0091] 8 glass pane [0092] 9 feed roller [0093] 10 closed belt conveyor [0094] 11 dosing roller [0095] 12 rectified conveyor [0096] 13 ball recirculating runners system [0097] 14 bracket [0098] 15 support for the applying roller [0099] 16 screw [0100] 20 bridge device [0101] 21 frame [0102] 22 feet for fixing to floor [0103] 23 supports for measuring sensors [0104] 24 measuring system [0105] 25 transversal photocell [0106] 26 blocking knob [0107] 27 PLC [0108] 31 idle roller [0109] 32 motorized roller [0110] 33 contrast roller [0111] 39 contrast roller