Abstract:
Disclosed is a linear conveyor ( 21 ) for transporting glass panels ( 3 ) in the vicinity of grinding stations ( 9, 13 ) or a washing station ( 15 ) of a system for producing glass panel blanks including a linear conveyor ( 23 ), for example, a driven toothed belt, and opposite the driven toothed belt a beam ( 25 ), from which a fluid, in particular water, is discharged. The glass panel ( 3 ) is pressed against the linear conveyor ( 23 ) in a non-positive manner and reliably conveyed by water discharged from the beam ( 25 ). Such linear conveyors ( 21 ) can be arranged at the upper or lower edge of a glass panel ( 3 ) in order to trim the glass panel using at least one grinding disk ( 27 ), for example.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a device for conveying plate-shaped elements—plates, such as (flat-) glass panels, for example. 
     2. Description of the Related Art 
     For the conveying of plate-shaped elements such as glass panels, there are a variety of devices. Known are devices that work with rollers and/or conveyor belts or conveyor chains. 
     A problem with the known conveying devices is ensuring the necessary traction between the element to be conveyed, such as a glass panel, for example, and the conveying means (rollers, conveyer belts, and so forth). Absolutely steady transport is necessary, for example, in the conveying of glass panels in grinding lines, in which the edges are to be ground (trimmed), on the one hand, and in, among others, washing and sealing systems, on the other hand. 
     BRIEF SUMMARY OF THE INVENTION 
     The object of the invention is to indicate a conveying device that ensures steady transport of vertical, or mostly vertically oriented, plate-shaped elements. 
     This object is achieved with a device according to the present invention that conveys flat workpieces. 
     Preferred and advantageous configurations of the invention are subjects of the sub-claims. 
     Steady transport is ensured since in the device according to the invention, a powered (linear) conveying means, such as, for example, a train of conveyor rollers or an (endless) conveyor belt, is provided on one side for conveying plate-shaped or panel-shaped elements (objects) such as glass panels and because the necessary traction between the (linear) conveying means and the element to be conveyed is ensured by at least one fluid cushion, which is provided on the side of the element to be conveyed facing the conveying means, first and foremost a cushion that consists of a liquid, especially a water cushion. In this case, the surfaces of the element to be conveyed that face the conveying means are not touched mechanically (i.e., by rollers, conveyor belts, etc.) because the element to be conveyed is loaded on this surface only by the fluid film (water film). This is especially advantageous when glass panels that have a coating on one side are to be conveyed as is the case, for example, with heat-reflecting glass or glass for photovoltaic elements and equipment. 
     The conveying device according to the invention can, for example, be used with grinding systems and/or washing systems or in systems used to manufacture insulated glass. 
     Within the scope of the invention, it may be provided that the element to be conveyed will be supported from beneath by supporting rollers or other means of support. The element to be conveyed may be supported from behind by a wall—an air cushion wall, for example—especially when the conveying plane is mostly vertical; the wall can, as is known per se, be tilted a bit rearward from the vertical, 5 degrees, for example. 
     Also taken into account within the scope of the invention is the provision of the conveying device both in the upper and the lower areas of an element to be conveyed. If the conveying devices according to the invention are used in, for example, glass-grinding lines, both the lower and the upper edges of the glass panels can be treated simultaneously by grinding. 
     The supporting rollers or ribbons (belts) that support the element to be conveyed from beneath can be, for example, powered or free-running supporting rollers (castors) of the supporting ribbons (belts). 
     The conveying device according to the invention is especially valuable in connection with machines that are designed to process the glass edges for solar elements. The edges and corners can thus be worked by abrasive disks, such as peripheral profiling disks, and/or abrasive belts (abrasive belts arranged crosswise) in a single pass, whereby, on the one hand, the cycle time of a follow-on hardening facility is achieved, while simultaneously the grinding quality remains constant over the entire service life of the abrasive disks and abrasive belts. 
     The tool-changing time is many times shorter than with conventional, horizontal procedures with multi-head grinding systems. 
     The transport devices according to the invention can also be deployed in facilities for edge grinding and face grinding of rectangular glass panels in a fully automatic cycle with (peripheral) abrasive disks and/or diamond abrasive belts. In this case, the glass panels are conveyed standing vertically through the facility, whereby they are supported on only one side (rear side) by the transport means (rollers or belts) and are pressed against the means of transport from the front by the fluid cushion, especially a water cushion. 
     In particular, a facility for grinding rectangular glass panels can comprise, for example, two grinding machines with a turning device arranged between them in such a way that it is possible to work all four edges of rectangular glass panels in a continual pass. 
     With the conveying device according to the invention, a glass panel can be transported standing nearly vertically in a grinding/edging system and can be worked on the upper and lower edges in continuous operation in the grinding system without being forcefully guided on the front, since while being processed, the pane is pressed against the means of transport by the fluid (especially water) cushion and is well stabilized while being processed in continuous operation. 
     When a system is being operated that is for the grinding/edging of rectangular glass panels with the help of abrasive disks and/or abrasive belts that are, for example, arranged cross-wise (cf. EP 0 920 954 A), a turning station can be provided between the grinding stations; this turning station can ensure that the glass panels are turned 90 degrees when the glass panel has left the first grinding station. In this case, it is possible to operate such that the glass panel that has been transferred into a loading station by a turning device is first oriented such that its long edges stand essentially vertically so that the shorter edges can first be processed (ground and/or trimmed). After leaving the first grinding system, the glass panel is turned again, so that the longer edges are now horizontally oriented and are processed in the second grinding system. The distance from the glass panel ahead of it is thus reduced, and the possibility exists of transporting it along into the following wash system nearly seamlessly. 
     The turning devices that are provided in the turning station preferably comprise a turning gripper with two arms that stand normally to each other, whereby the grippers can pivot around an axis that stands vertical to the conveying plane. It is preferably provided that the arms of the turning device are equipped with fingers that are arranged to be able to pivot on the arms of the turning device from a position (working position) that stands normally to the conveying plane or to the plane defined by the two arms of the turning device, to a position (preparation position) parallel to said plane. This designing of the turning device with pivoting fingers ensures that the turning devices in the turning stations touch the workpieces (glass panels) that are leaning on the support wall—an air cushion support wall, for example—only on their edges and that the opposite (front) side facing the support wall that is equipped with, for example, a coating or for photovoltaics is not touched when being turned in the turning stations. To swing the turning devices back in the turning stations, the fingers are pivoted into their preparation position, so that they have clearance from the glass panels that are behind them or are being transported through; these panels can thus just be transported through the turning station, for example, when no turning operation is necessary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further details, features, and advantages of the invention are presented in the following description of preferred embodiments of a device according to the invention based on the drawings. 
       Here: 
         FIG. 1  shows in the example a facility with two grinding stations and one washing station, as well as with two turning devices, 
         FIG. 2  shows a grinding station schematically, 
         FIG. 3  shows another configuration of a grinding station from the front, 
         FIG. 4  shows the grinding station from  FIG. 3  from the rear, 
         FIG. 5  shows a detail of the grinding station from  FIGS. 3 and 4 , 
         FIG. 6  shows a detail of the water cushion beam, 
         FIG. 7  shows a detail of the water cushion beam in a different configuration, 
         FIG. 8  shows a turning station, and 
         FIG. 9  shows the turning station from  FIG. 8  from a different perspective. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A facility shown in  FIG. 1  for manufacturing glass panels with ground/trimmed edges comprises a loading station  1 , in which glass panels  3  coming from a glass cutting device or a storage unit are transferred to the facility. After the loading station  1 , a first turning station  5  with a first turning device  7  is provided, which turning device orients the glass panels  3  that have been transferred to the facility in such a manner that their longer edges stand vertically. In the subsequently provided first grinding station  9 , the upper and lower horizontal edges of the glass panel  3  are continuously processed, especially ground and/or trimmed. 
     After the first grinding station  9 , a second turning station  11  is provided with a second turning device  7 , which rotates the glass panel  3  by 90 degrees, so that the edges of the glass panel  3  that have not yet been processed (the longer edges) are now horizontally oriented. Behind the second turning station  11  is a second grinding station  13 , in which the now horizontally oriented (longer) upper and lower edges of the glass panel  3  are processed (ground/trimmed). Subsequently, a washing system  15  is provided in which the trimmed glass panels  3 , which can be coated glass panels  3  and/or glass panels  3  for solar arrays, are washed. 
     In the grinding stations  9  and  13  and in the washing station  15 , devices  21  are provided for transporting the glass panels  3 , such as are shown in greater detail in  FIGS. 2 and 5 . These conveying devices  21  are each composed of a powered toothed belt  23  (or a series of toothed belts) and a water cushion beam  25  arranged relative to the latter. Below the arrangement  21  of toothed belts  23  and water cushion beams  25 , rollers  28  (optionally powered) are provided, on which rollers the glass panel  3  that is to be transported (conveyed) stands. 
     Devices  21  consisting of toothed belts  23  (as linear conveying means) and water cushion beams  25  (fluid cushion beams) are arranged on the upper and lower edges  2 ,  4  of the glass panel  3 , such that the glass panel stands with its upper edge  2  facing upward and its lower edge  4  facing downward. Thus, processing can be done by grinding disks  27  and grinding belts  29  ( FIG. 5 ). 
     Here, the upper device  21 , comprising a water cushion beam  25  and a belt drive  23 , is vertically adjustable, as is especially shown in  FIGS. 3 and 4 . 
     A first possible embodiment of a water cushion beam  25  (device used to press a glass panel  3  against the linear conveying device  23 ), which can also be driven by a gaseous fluid, is shown in  FIG. 6 . In this embodiment, the fluid (gas or especially water) is forced through two narrow slots  51  into the space  53  between the glass panel  3  and the water cushion beam  25 , so that according to Bernoulli&#39;s principle, as is indicated by arrows in  FIG. 6 , the glass panel  3  is held at a constant distance from the water cushion beam  25  without being touched by it and is simultaneously pressed against the conveyer belt  23  of the linear conveyer. 
     A different embodiment of a fluid or water cushion beam  25  is shown in  FIG. 7 . Here, fluid (gas or especially a liquid, such as water) is forced out of two slotted openings  55  into the space  53  between the water cushion beam  25  and the glass panel  3 . The exit ports  55 , through which the fluid (water) exits, are in this case tilted such that they are placed obliquely with respect to each other so that in the area between the discharge nozzles  55  (these are slit nozzles, for example), an elevated pressure forms that presses the glass panel  3  as a workpiece firmly against the belt drive  23 , so that the necessary traction for secure transport of the workpiece (glass panel  3 ) is achieved. 
     In both the embodiment according to  FIG. 6  and the one according to  FIG. 7 , it is possible to design the water cushion beam  25  with the cross-sectional shape, shown in  FIGS. 6 and 7 , in one piece over the entire length, or alternatively assembled together in multiple sections, whereby it is taken into account that in each case round elements are provided, so that the outlet nozzles  51  and  53  are ring nozzles. Nevertheless, elongated elements are preferred for the water cushion beam  25  with slit nozzles ( 51 ,  53 ). 
     The glass panels  3  are pressed by the water cushion beam  25  against the linear conveying means  23 , for example the endless toothed belt or the series of endless belts or a train of powered rollers, so that the necessary traction is ensured, and the glass panel  3  can also be processed during the processing by abrasive disks  27  and/or trimming belts  29  (diamond belts, cf.  FIG. 5 ) that are, for example, oriented crosswise. 
     In this case, it is provided that the endless belts  23  of the linear conveying means of the conveying device according to the invention are, over their entire lengths, supported from within—i.e., from the side that faces the glass panel  3 —so that the necessary traction between the glass panel  3  to be conveyed and the linear conveying means  23  is ensured in all areas. 
     The lower and/or upper water cushion beam  25  can be adjustably mounted in the machine frame vertical to the conveying plane (plane of the glass panel  3 ). The pressure with which the glass panel  3  is pressed by the fluid (water) cushion between beams  25  and glass panel  3  against the linear conveying means  23  (for example, the toothed belts) can thus be varied in order to choose the pressure suitable for the strength (thickness) of the glass panel  3 . In this case, it is preferable for the force with which the water cushion beam(s)  25  are loaded against the glass panel  3  to be ascertained by sensors (“force sensors”). These sensors can be functionally combined with the adjustment drive for the (adjustable) water cushion beams  25 . 
     When the grinding stations  9 / 13  are designed as shown in  FIGS. 3 and 5 , it is possible to use either only the grinding heads  27  or only the grinding belts  29 , or, alternatively, both the grinding heads  27  and the grinding belts  29 ; whereby the grinding belts  29  serve especially to remove (minute) defects on the edges of the glass panels  3  by trimming. 
     Because, according to the invention, a (fluid) water cushion beam  25  is used, not only is a damping effect achieved on the processed glass panel  3 , meaning that vibrations in the glass panel  3  are suppressed, but also a higher power transmission is ensured. Additionally, cooling of the glass panel  3  is ensured during the treatment by grinding and/or trimming, and cleaning is similarly ensured by running it through running water, in that grinding debris is washed away by the water that comes from the water cushion beam  25 . 
     Details of the turning mechanism (turning device  7 ) are outlined below according to  FIGS. 8 and 9 . 
     The turning devices  7  provided in the turning stations  5  and  11  comprise, as shown in  FIGS. 8 and 9 , two arms  31 , which together encompass a right angle. The arms  31  can be connected together by a connecting beam  33  in order to increase stability. A drive  37  is provided for pivoting the turning device  7  around an axis that runs perpendicular to the conveying plane of the glass panels  3 , which axis is in the area of the lower horizontal conveyor  35 , which in the example shown is a series of rotary-driven conveying rollers. With the drive  37 , the turning device  7  can be pivoted 90 degrees in order to turn glass panels  3 . 
     Each of the two arms  31  of the turning device  7  is equipped with a row of fingers  39  ( FIG. 9 ). The fingers  39  can pivot on the arms  31  around an axis that is parallel to the longitudinal extension of the arm  31 , so that they are pivoted out of the operating position shown in  FIG. 9  in which they stand perpendicular to the conveying plane and to the plane of the supporting wall  41  (this wall is an air cushion wall in the embodiment shown), into a position parallel to the conveying plane (=plane of the supporting wall  41 ). 
     When a glass panel  3  is pivoted, the fingers  39 , which are pivoted into their operating position (normally to the supporting wall  41 ), grip the edges of a glass panel  3  to be turned, so that the panel, sliding on the air cushion of the support wall  41 , is touched only on its edges; i.e., the surface facing away from the supporting wall  41  is not touched. In this way, a gentle turning is ensured, whereby scratching or damaging of the front side of the glass panel  3  and/or a coating (photovoltaic elements) that has been affixed to it is precluded. 
     The rollers  35  of the linear conveyor on the lower edge of the supporting wall  41  can be powered by a drive, not shown. 
     In summary, an embodiment of the invention can be described as follows. 
     A linear conveyor  21  for transporting glass panels  3  in the area of grinding stations  9 ,  13  or a washing station  15 , a facility for the manufacturing of glass panel blanks, has a linear conveyor  23 , for example a powered toothed belt; across from this lies a beam  25 , out of which a fluid, especially water, exits. The glass panel  3  is clamped firmly against the linear conveyor  23  by the water exiting the beam  25  and securely conveyed. Such linear conveyors  21  can be arranged on the upper or lower edge of a glass panel  3  in order to, for example, trim said panel using at least one abrasive disk  27 . Correspondingly, linear conveyors  21  may also be provided in a washing station  5 ,  11 . To pivot the glass panels  3  90 degrees, so that first both the upper and lower edges and then the initially vertical edges of the same can be processed, turning stations  5 ,  11  are provided; these turning stations have turning grippers  7 , on which pivotable fingers  39  are provided that, to pivot glass panels  3 , touch them only on their lateral edges.