Patent Application
20100243148
This invention relates to an apparatus and a corresponding method for the so-called lamination of solar modules with this apparatus. The invention relates particularly to a production line for the form-cutting and application, or laying, of lamination foils in the manufacture of solar modules.
In principle, photovoltaic or solar modules are manufactured in that, on a front-side carrier plate made of, for example, glass, from its back-side, i.e. with the optically active side down, the individual solar cells and their connecting contacts (strings), or foils coated with the light-sensitive substances, are laminated with a back-side cover plate or cover foil. Immediately thereafter, or in a later work operation, the stacked layers are laminated by underpressure and heating.
Accordingly, use is made of, for example, lamination foils of EVA (ethylene vinyl acetate), PVB (polyvinyl butyral) or ionomers (thermoplastic materials as, for example, nafion), and back-side foils of tedlar (polyvinyl fluoride). These foils are supplied on stock rolls and cut to the required dimensions.
When manufacturing thick-film solar modules, in which predominant use is made of crystalline silicon, the required laying and cutting accuracy is low, because the foil that projects after the lamination can be simply cut away. In consequence, the accuracy requirements of conventional foil-cutting machines are also low.
The accuracy requirements are, however, significantly higher for the manufacture of thin-film solar modules, in which amorphous silicon, or cadmium telluride (CdTe), or copper-indium diselenide (CIS) is used. In particular with thin-film solar modules, the permanent encapsulation takes on a particular importance, since penetrating humidity and thus-caused corrosion can substantially shorten the life of the module and also impair its efficiency through undesired electrical connections of the current-carrying components. As protection against the penetration of moisture, for example the front-side carrier plate or glass plate, and the back-side lamination or cover plate (in most cases another glass plate), are sealed with an edge seal, e.g. with butyl. The lamination foil must therefore be laid with perfect fit between the sealing strips so that, on completion of lamination, no air bubbles are present, and the lamination foil does not come to rest on the sealing strips, as a result of which a reliable and long-term stable sealing would be impaired.
Depending on the application (tape or hot melt), application of the sealing strips or butyl tapes is associated with great inaccuracy (up to +/−3 mm), and the glass carrier plate also has tolerances of up to +/−1 mm. Cutting of the lamination foil and laying it onto the butyl frame are each subject to a tolerance of +/−1 mm, so that a total inaccuracy of +/−6 mm results.
Depending on the material and thickness, the lamination foil can compensate tolerances, or even an intentionally left gap, through its specific flow length and surface spreadability during the laminating operation; these material properties are, however, limited, the more so, the thinner the lamination foil. With a view to saving material and conserving resources, it is, however, desirable to use lamination foils that are as thin as possible. The cutting and laying accuracy thus takes on an even greater importance.
Conventional foil cutters, which are used for form-cutting foils for thick-film solar modules (crystalline segment), provide too little accuracy for use in the manufacture of thin-film solar modules. The conventional foil cutters from other technical areas which are used, for example, in the automobile industry for making laminated glass windows, also provide too little accuracy. A corresponding example is known from patent application EP 319 251 A2. This document describes an apparatus and a method for laminating glass. It particularly relates to placing an intermediate layer between two glass sheets, which are to be joined together by lamination. EP 0 319 251 A2 proposes working with electrostatic charge to position the intermediate layer. For the manufacture of sensitive solar modules, such a method is out of the question. In the manufacture of solar modules, electrostatic charges are consciously avoided.
Published US patent application US 2006/0219364 is concerned with feeding ceramic green compacts by means of a carrier film, form-cutting the ceramic green compacts to shape, and then laminating the form-cut green compacts. This method cannot be transferred to the lamination of solar modules, since the latter are not fed and form-cut by means of a carrier film. As an alternative, so-called plotters are used, which attain a higher cutting accuracy by means of oscillating blades. However, the laying accuracy of the form-cut lamination foil on the carrier plate remains unchanged low.
Furthermore, these systems operate with cutting mats. Since such systems form-cut a foil approximately every 30 seconds or even faster, and in 24/7 operation, the cutting mats are destroyed in a very short time by the high usage and the constantly identical geometry. Their use results in excessively high costs and machine downtimes. The alternative, of always moving the lamination foil to be form-cut by a few millimeters, and thereby better utilizing the cutting mat, also results in substantial costs on account of the consequently larger cutout of the lamination foil.
The purpose of the present invention is to provide an apparatus, and a corresponding method that makes use of this apparatus, with which a greater accuracy can be attained, cutting is generally optimized—through, for example, in particular no cutting mats being used, less material consumption and wear occur, and thereby the costs are reduced.
The solution to the purpose consists firstly of eliminating the inaccuracy that occurs through the transfer of a holding apparatus for the lamination foil during the cutting operation to a gripper for the form-cut lamination foil during the laying operation. The apparatus according to the invention, or the method according to the invention, foresees that the holding apparatus for form-cutting is obviated in that, for laying, the gripper takes over holding of the lamination foil during cutting. This also obviates the source of inaccuracies that occur through the transfer of the lamination foil from the form-cutting process to the laying process.
Moreover, the apparatus according to the invention, or the method according to the invention, foresees a cutting operation in which cutting mats are no longer needed. For this purpose, a sub-apparatus of the total apparatus is foreseen which, by means of a pullout unit, pulls out and cuts off from the stock roll the lamination foil of a defined size and places it exactly positioned on a cutting table. This positionally accurate placement, and the dimensions of the cutting table, are chosen in such manner that the pre-cut lamination foil is laid with only a very small overlap over the edges of the cutting table. The inherent structural strength of the lamination foil, and a fixation of the lamination foil on the cutting table—for example by sucking on with a vacuum—allow such a free cut “in the air” along the edge of the cutting table, which can take place without the counterpressure of a cutting mat. The cost-intensive utilization of the cutting mats is thereby obviated and the wear of the cutting blades is appreciably reduced, since they now only cut the relatively soft lamination foil and no longer come into contact with a cutting mat that is as hard as possible. Furthermore, the positional accuracy, and the only little overlapping of the lamination foil on the cutting table, ensure a material-saving occurrence of offcut.
According to the invention, the cutting operation of the lamination foil on the cutting table is further improved in that the grippers that hold the foil—preferably a vacuum gripper—has a frame that surrounds the external contour of its supporting surface which has identical external dimensions to those of supporting surface of the cutting table. The piece of lamination foil that is to be form-cut is thus not only held by, for example, suction cups of the gripper, but in addition gripped by this frame, or pressed onto the laying surface of the cutting table from above in the area of all four external corners.
A further optimization of the cutting operation takes place through the arrangement according to the invention of four cutting blades, which process all four edges simultaneously. For this purpose, four cutting heads are arranged one on each rail of a frame. When out of operation, the four cutting heads are preferably parked in a parking position, and when in operation, travel each by means of an own drive along a respective guide rail. On completion of the cutting operation—controlled, for example, by a thrust-reversing end-switch or sensor—the cutting heads travel back into their parking position.
In this manner, optimization of the entire cutting operation, which is composed of four individual cutting operations, is attained with regard to its speed as well as its accuracy.
The cutting heads preferably execute their cutting movements simultaneously by means of a programmable control. A circuit is, however, realizable, in which the start of a first cutting head triggers the start of a second cutting head, this start in turn triggers the start of a third cutting head, and this start in turn triggers the start of a fourth cutting head.
Moreover, the cutting heads are preferably equipped with a manually actuatable spindle or a preferably electric drive to displace the cutting blade.
The cutting blades are preferably embodied as rotating circular cutting disks. However, use can also be made of translationally moved, fixed, or oscillating blades, or also of lasers.
Optionally, and to avoid possible machine downtimes, provided for the cutting blade in its parking position is a sharpening apparatus, which is combined with a further, vertically-acting displacement. That is to say, a reducing diameter of the cutting disk that is caused by operation, or also by sharpening, is readjustable until a sensor signals to the cutting head a diameter that has become excessively small.
As stated above, the lamination foil is held on the cutting table by the suction action of the cutting table, as well as by the gripper which subsequently executes laying of the cut lamination foil on the carrier plate. On the cutting table or on the gripper, further cutting blades, or lasers, or a stamping device can therefore be integrated, which exercise a rounding-off, or a further form-cutting, beyond the form of a simple square or rectangle.
There are solar modules that provide special contacting variants by means of holes or recesses that are provided for this purpose. The additional cutting blades, lasers, or stamping devices described above can optionally also be used to apply the required holes or recesses, it being possible for these devices to be arranged on the cutting table, or on the gripper, or on both.
According to a further variant embodiment, the cutting heads, and the rails along which they travel, are integrated on the side walls of the cutting table. The frame of a form-cutting unit above the cutting table, which is formed from the rails, is thus obviated, and allows free access of the gripper to the form-cut lamination foil without the cutting unit needing to be previously moved, or the lamination foil needing to be lifted out of the gripper through the frame. In this variant embodiment, the need for a parking position for the cutting heads outside the form-cut surface of the lamination foil is thus essentially and advantageously obviated.
So that in the interest of constructional simplicity in the last-mentioned variant embodiment the cutting heads cut on the side surfaces of the cutting table directly from underneath the lamination foil that is to be form-cut, the lamination foil does not, however, through the pressure of the cutting blade, raise itself, the gripper is preferably embodied in the form of a stamp, with an exactly fitting supporting surface, which thus in turn results in an edge that supports a precise cut.
The cutting table, and also the gripper, is preferably embodied in such manner that a plane surface has apertures which are filled with porous and non-slipping material. Applied to the back-side of the openings is preferably a vacuum, so that the lamination foil is sucked onto the suckers of porous material. Optionally realizable for this purpose is also a variant embodiment with classical suction cups, or also one in which the suckers or suction cups are dispensed with, and the surface of the cutting table, or of the gripper, in its entirety forms a suction bell. It must here be observed that the size of the suction bell, or the sucking-in force, does not cause excessive curvature of the lamination foil. The herewith disclosed holding variant of the lamination foil, whether with suction cups or suckers or a suction bell, can be realized not only for the cutting table, but also for the (vacuum) gripper.
Furthermore, the apparatus according to the invention has a pull-out unit that is combined with a cutting-off unit. These two units serve to grip, cut off, and pull onto the cutting table from the stock roll an adequate, subsequently to be form-cut, piece of lamination foil.
The cutting-off unit has, as has also the form-cutting unit, a preferably electrically driven cutting head which is drivable on a rail in the Y direction. The Y direction is perpendicular to the unrolling direction of the lamination foil from the stock roll. Also this cutting head of the cutting-off unit has a rotating cutting disk, or a stationery or an oscillating blade, or a laser, as a cutter. The cutting-off unit preferably has in addition a roller drive, with which an advance of the lamination foil takes place.
The cutting-off unit has, in addition, a gripping rail, which according to the invention fulfills two purposes. Firstly, by means of preferably pneumatically driven levers, the gripping rail grasps and holds the lamination foil for a clean cut. Secondly, however, the cutting-off unit, on completion of the cut, bevels the cut edge of the lamination foil upward, or also only raises it, in that—also preferably pneumatically—a push-up with an inclined end-face pushes the cutting edge of the lamination foil up from below. The inclined end-face of the push-up can be inclined at an angle of from 5 to 45 degrees, preferably, however, has an angle of 30 degrees, so that on completion of beveling, or on completion of pushing-up, an optimal transfer of the pre-cut piece of the lamination foil by grippers of the pull-out unit can take place.
Preferably, several grippers of the pull-out unit are also fastened at a corresponding angle of from 5 to 45 degrees, preferably of 30 degrees, onto a beam of the pull-out unit. The grippers are preferably pneumatically actuated and can be moved synchronously by an electric drive in the X direction by moving the beam in the longitudinal direction. Preferably, the grippers can also be moved in the plane that is formed by its angular position, i.e. along its longitudinal axis, by means of a pneumatic carriage unit. The grippers have gripper jaws which can be closed and opened preferably also pneumatically.
An alternative variant embodiment for this purpose foresees that the grippers of the pull-out unit grasp the lamination foil directly at the stock roll before cutting-off takes place. The grippers pull the lamination foil onto a cutting table of the cut edge of the previous piece of foil as far as one or more stops, end-switches, or sensors. When this—preferably settable—end-position is reached, the piece of lamination foil that is to be processed is cut off by a cutting head on the cutting table at a defined and preferably also settable distance. Hence the leading edge of the piece of foil is no longer cut first as formerly, but the trailing edge (towards the stock roll) of the piece of foil is cut immediately. This piece of foil thus comes to rest on the cutting table, and can lose any possible tension that can arise through pulling-off from the stock roll. Subsequently, the piece of lamination foil that is to be further processed is pulled onto the cutting table not by the formerly disclosed pull-out unit, but by the (vacuum) gripper, which subsequently holds the lamination foil during final form-cutting, and even later lays it on the carrier plate. Relative to the formerly disclosed variant embodiment, this variant embodiment has, firstly, the advantage that the formerly disclosed pull-out unit with inclined grippers and the beveling and pushing-up process can be obviated and less offcut occurs. Secondly, a further source of inaccuracy is also eliminated, in that additionally a further transfer less takes place, specifically that from the pull-out unit to the cutting table.
In this last-described variant embodiment, the grippers of the pull-out apparatus, which grasp directly by the stock roll, are preferably embodied as vacuum tongs which do not damage the surface of the lamination foil. In this manner it can be achieved that the cut edge of the previous piece of foil can itself be used as the definitive cut edge in the extreme X direction, so that also on this edge absolutely no more offcut occurs. The cutting table is preferably displaceable relative to an extendable stop on the new (stock roll) cut edge in the X direction towards the stock roll, so that the opposite cut edge becomes free for gripping by the vacuum tongs.
The variant embodiments that are described can also be reduced to an apparatus or a production line according to the invention in which the lamination foil is supplied in the form of pre-cut and stacked sheets. This can then be realized either in that the previously described pull-out unit pulls the uppermost sheet of lamination foil from the stack or, as described above, the (vacuum) gripper of the laying unit executes not only the holding function when form-cutting but, in addition, also executes fetching the uppermost sheet of lamination foil from the stack.
All of the disclosed variant embodiments eliminate the sources of error that result from the form-cutting itself as well as from the transfer of the lamination foil from the cutting process to the laying process. The variant embodiments that are described therefore present advantages which manifest themselves as higher processing accuracy, more efficient and material-conserving processing, and hence more accurate and less costly end-products.
However, a remaining source of error are the inaccuracies that still exist due to the application of the butyl sealing. To eliminate these also, a variant embodiment of an apparatus according to the invention is conceivable in which a high-resolution camera creates an image of the carrier plate with the applied butyl sealing. The information from this image is transmitted digitally to the control of the form-cutting unit and, before form-cutting of the lamination foil, positions the cutter exactly and according to need. Particularly cutters that cut with, for example, a laser head that is controllable in the X and Y directions would thus be able to form-cut a lamination foil which, taking into account an expansion gap, can be fitted with high precision into a butyl sealing frame of any degree of inaccuracy.
Preferably on account of a displaceability of the relevant holding apparatus and grippers, the apparatus according to the invention is suitable for laminating thin-film, as well as thick-film, solar modules.
The invention is explained in greater detail symbolically and exemplarily by reference to figures. The figures are described interrelatedly and overall. They present diagrammatic and exemplary illustrations and are not to scale, also not with regard to the relations between the individual components. Identical reference symbols indicate identical components, reference symbols with different indices indicate functionally identical or similar components. The above as well as other advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which:
The following detailed description and appended drawings describe and illustrate various exemplary embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. In respect of the methods disclosed, the steps presented are exemplary in nature, and thus, the order of the steps is not necessary or critical.
The carrier plate 1, or the cover plate, represents the optically active side of the subsequent solar module and is fed by the transport system 4a on its front-side, i.e. with its back-side facing up. Not shown here in greater detail is a sealing frame of, for example, butyl, which can be applied to the back-side of the carrier plate or to the back-side of the cover plate itself.
On completion of the form-cutting and laying operation of the lamination foil 2 onto the carrier plate 1, a cover plate 3 is laid over the latter by a turnover module 5. In the case of the application of the sealing frame onto the covering plate, the latter can be delivered by the transport system 4a, the lamination foil 2 laid thereupon, and then with the turnover module 5 the carrier plate 1 laid thereupon. The thus laminated and sealed solar module is then removed by a transport system 4b to a laminating apparatus that is not shown in more detail.
By means of a roller system 7, the lamination foil 2 is rolled off from a foil unroller 6 and comes to lie on a laying table 8. The laying table 8 is so dimensioned that a cutting-off unit 300 cuts off a sufficiently large piece of foil for subsequent processing in that a holding apparatus 400 holds the lamination foil 2 and cuts the cutting-off unit 300 in the Y direction.
A pull-out unit 500 then pulls with grippers 600 the piece of lamination foil 2 over a cutting table 700. Not only this cutting table 700, but also a form-cutting unit 200 and a vacuum gripper 800, are arranged on a base-frame 9 that has guide rails 10a and 10b. Along the latter, the vacuum gripper 800 is arranged displaceably in such manner that it can take up a form-cutting position ZP above the cutting table 700—preferably controlled with sensors or end-switches.
The lamination foil 2 that is lying on the cutting table 700 is then held both by the cutting table 700 itself and by the vacuum gripper 800 which, after reaching the horizontal position (displacement in the X direction) above the cutting table 700, is also displaceable vertically (displacement in the Z direction). The form-cutting unit 200 then form-cuts the lamination foil 2, and thereafter, according to an aspect of the present invention, the holding of the form-cut lamination foil 2 by the vacuum gripper 800 is maintained. Consequently, no further transfer to a separate laying apparatus takes place, since the vacuum gripper 800 travels with the form-cut lamination foil 2 in the X direction on the guide rails 10a and 10b into a laying position AP above the carrier plate 1 that lies ready. In the course of its processing within the apparatus 100, the lamination foil 2 thus describes a path from the form-cutting position ZP to the laying position AP in which it is held by the vacuum gripper 800.
The carrier plate 1 on the laying position AP, the feeder transport system 4a, the removal transport system 4b, and the combined usable vacuum gripper 800, form a laying unit 900.
In the interest of greater clarity,
The pull-out unit 500 is further shown with several grippers 600 arranged on a beam 13. The beam 13 is movable in guide rails 10c and 10d in the X direction. Furthermore,
The vacuum gripper 800 is shown in the laying position, however in this view the carrier plate and the transport system are not shown. The vacuum gripper 800 has two struts 15a and 15b which run with guide elements 16a and 16b in the guide rail 10b and with corresponding guide elements 16c and 16d in the guide rail 10a.
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In the form shown, the pull-out unit 500 is embodied as a linear carriage unit. Under certain circumstances this can be disadvantageous in that, on completion of a pull-out motion, the gripper 600 must release the lamination foil again so as to then return in the opposite X direction into a starting position for the next piece of lamination foil. This return motion can, however, stand in the way of a further processing step in the form of a lowering of the vacuum gripper. For this reason, also disclosed here is a variant embodiment in which the pull-out unit 500 is returned to its starting position in circular- or oval-shaped guide rails 10c and 10d. Also to be included in this disclosure is a variant embodiment in which the gripper 600, on completed pull-out of the lamination foil, is pushed apart in the Y direction and a return path outside the action radius of the vacuum gripper is linearly described.
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Starting out from the parked position of the cutting heads 14a-14d, an, for example, simultaneous cut of all four cutting edges of the piece of lamination foil 2 is possible, when the cutting heads 14c and 14d start as soon as the cutting head 14b has released the path for the cutting head 14c, and the cutting heads 14c and 14d cut with a higher speed. This higher speed must, at least with regard to the possibility of a collision between the cutting heads 14b and 14c, be chosen in such manner that the cutting head 14c has completed its work before the cutting head 14b has returned to the shown parking position.
A cutting movement of the cutting heads 14a-14d is programmably controllable and wherein parking positions are allocatable to the cutting heads. A programmable control 201 exchanges movement control signals with the cutting heads 14a-14d over lines 202. Data information for the positions of the cutting heads 14a-14d is generated from a camera 203 and can be input into the programmable control 201 over a line 204.
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A further characteristic according to the invention which is not shown in more detail is a frame 45a which is arranged on the gripper plate 45 of the vacuum gripper 800. This frame 45a surrounds the external contour of the laying surface of the gripper plate 45, and has external dimensions which are approximately identical to the external dimensions of the laying surface of the cutting table 700. This frame 45a thus fulfils an additional holding function of the piece of lamination foil 2 which is flush and positionally accurate with the external edge of the cutting table 700.
In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.
| Number | Date | Country | Kind |
|---|---|---|---|
| 09156517.6 | Mar 2009 | EP | regional |
