Abstract:
In order to seal the corner joint of an elastoplastic tape placed as a spacer on a glass pane, a film strip is pressed with a first portion of its length against the first leg section of the spacer and the protruding portion of the film strip is wrapped around the corner and pressed against the second leg section. For the purpose of automating this process, the film strip is severed mechanically from an automatically supplied film tape and held via a transfer apparatus which thereafter presses the film strip with the first portion of its length against the first leg section. The portion of the film strip protruding freely over the corner is wrapped around the corner via a pressure carriage and pressed by tautening against the second leg section of the spacer.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 11/633,620, filed on 5 Dec. 2006 and entitled “A Method and Apparatus for Sealing the Corner Joint of the Spacer of an Insulating Glass Pane,” which claims priority under 35 U.S.C. §119 to Application No. DE 102005058028.9 filed on 5 Dec. 2005, entitled “A Method and Apparatus for Sealing the Corner Joint of the Spacer of an Insulating Glass Pane.” The disclosure of each aforementioned application is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     It is known that insulating glass panes need to be sealed so as to be resistant against diffusion of water vapor. For this purpose, a permanently plastic adhesive, which usually is butyl, is applied to both lateral sides of the spacer. In the case of a spacer made of an elastoplastic tape which often consists of several functional layers and is gas-diffusion-tight, a joint is produced inevitably between the “beginning” and the “end” of the tape placed on the one glass pane. Spacers placed or applied mechanically frequently start and end in the region of a corner of the respective glass pane because the mechanical transport processes of the glass pane will be simplified. To ensure that diffusion tightness is also ensured in the area of this so-called corner joint, a film strip made of plastic for example is currently glued onto the corner by hand. 
     SUMMARY OF THE INVENTION 
     The invention relates to a method and an apparatus for sealing the corner joint of an elastoplastic tape placed on a glass pane as a spacer by pressing an oblong film strip which is adhesive on one side with a width which is substantially equal to the width of the elastoplastic tape against the leg sections of the spacer converging in the corner joint, with the film strip being pressed with a first portion of its length against the first leg section and the portion which at first protrudes freely beyond the corner is wrapped around the corner and pressed against the second leg section. As a result, the last gap is thus virtually closed in the otherwise fully automated production process of insulating glass panes in a long production line, which starts with the raw glass panel and ends with the insulating glass pane ready for shipment. 
     The above and still further features and advantages of the present invention will become apparent upon consideration of the following definitions, descriptions and descriptive figures of specific embodiments thereof wherein like reference numerals in the various figures are utilized to designate like components. While these descriptions go into specific details of the invention, it should be understood that variations may and do exist and would be apparent to those skilled in the art based on the descriptions herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The method according to the invention and the apparatus for carrying out the method are explained below by reference to an embodiment and the schematically simplified drawings. 
         FIG. 1  shows a perspective top view of a film tape feed. 
         FIG. 2   a  shows the respective perspective bottom view, supplemented by a number of further parts. 
         FIG. 2   b  shows the respective view obliquely from above. 
         FIG. 3  shows the part of the apparatus adjacent to  FIG. 1 , especially the clamping and cutting apparatus. 
         FIG. 4  shows the transfer apparatus for the film tape in the advanced position in which it presses the film strip against the one leg section of the spacer. 
         FIG. 5   a  shows the situation similar to  FIG. 4 , but with retracted transfer apparatus and supplemented by a pressing apparatus for the first part of the film strip and a pressure carriage for turning and pressing the part of the film strip previously protruding freely over the spacer corner. 
         FIG. 5   b  shows the parts shown in  FIG. 5   a  in a top view. 
         FIG. 6   a  shows the pressure apparatus and the pressure carriage directly before the turning of the film strip about the spacer corner. 
         FIG. 6   b  shows the parts shown in  FIG. 6   a  in a top view. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 to 6   b  show the relevant parts of an apparatus for the automatic placement of an adhesive film strip on the corner joint of the spacer placed on two glass panes. The apparatus is integrated in a known line for the automated production of insulating glass panes and is arranged for example directly after an apparatus for applying an elastoplastic tape as a spacer known, for example, from DE-B-102 12 359. When the glass panes are conveyed and processed, as is currently customary, in an upright manner (but slightly inclined against the vertical line), the present corner sealing apparatus is mounted in its entirety on a carriage which is guided in the longitudinal direction on a pillar and is positioned via the data of the respective glass pane supplied by the machine control system in such a way that the corner sealing apparatus is aligned towards the corner joint before the apparatus starts to work. 
       FIG. 1  shows a supply reel  1 , from which a film strip  2  can be withdrawn via a deflection roller  3  and two conveyor rollers  5  and  6  driven by a stepper motor  4 . The film strip can comprise plastic, especially of a multi-layer composite plastic with at least one diffusion-tight layer, or of a metal, e.g. an aluminum foil or a foil made of stainless steel or a metal/plastic composite film. The film strip  2  comprises on one side a layer  2 . 1  made of a polymerizing adhesive, e.g., including acrylate and/or butyl. An adhesive layer is especially advantageous which includes a middle strip that comprises butyl and one acrylate-based adhesive strip each on either side of the same. The adhesive layer  2 . 1  exposes an upper and lower edge strip of the strip  2 . The conveyor roller touches only the strip  2  in the area of the adhesive-free edge strip. The adhesive side of the strip  2  is covered by a protective film  2 . 2  which is pulled off during the withdrawal of the strip  2  via a deflection roller  7  and is wound up on a disposal roller  8 . According to a further development which is not shown, a middle strip of tenacious butyl is applied via a nozzle onto the layer  2 . 1  on the basis of acrylate after the withdrawal of the protective film  2 . 2 . 
       FIGS. 2   a  and  2   b  show the partial apparatus in  FIG. 1  in an oblique bottom view and an oblique top view, each supplemented by a jaw  20  which follows the conveyor rollers  5 ,  6  and is displaceable via a compressed air cylinder  20 . 1  in the conveying direction of the strip (see arrow in  FIG. 1 ) and is part of a subsequently described clamping apparatus. 
     As shown in  FIG. 3 , the synchronously driven conveyor rollers  5 ,  6  (e.g., via a toothed belt) convey the strip  2 , which is shown here for the purpose of better clarity only until shortly after the conveyor rollers  5 ,  6 , between the jaws  20 ,  21  of a clamping apparatus. Jaw  20  comprises numerous suction bores  20 . 2  in its strip contact surface situated in the strip transport plane and a suction air connection  20 . 3 . Jaw  21  is displaceable from the illustrated position at a right angle to the strip transport plane via a working cylinder  21 . 1  with indicated compressed air connections  21 . 2 . In the forward position the jaw  21  holds the strip  2  via plastic buffers (not shown in this view) against the respective contact surface of the jaw  20 . The buffers are situated at the level of the adhesive-free edge strips of the strip  2 . The suction bores  20 . 2  of the jaw  20  ensure that the strip which is not clamped over its entire surface remains crease-proof during the subsequent transport process. 
     A transfer apparatus  23  follows the clamp  20  in the direction of the strip transport, which transfer apparatus is spaced from the jaw  20  via a continuous slot  22 . The transfer apparatus  23  also comprises suction bores  23 . 1  in its strip contact surface and a respective suction air connection  23 . 2 . It is displaceable via a compressed air drive  23 . 3  in the strip transport direction. 
     A knife  30  is aligned towards the slot  22  which is situated at the end of a knife carrier  31  which on its part is downwardly displaceable from the illustrated idle position for severing a film strip from the strip  2 . For this purpose, the knife carrier  31  is connected via guide rods  31 . 1  with a compressed air drive  32 . 
     The film strips are produced as follows: while the transfer apparatus  23  is situated in the position as shown in  FIG. 4 , the stepper motor  4  in  FIG. 3  slides the strip over the transport rollers  5  and  6  in the transport direction by the width of the film strip to be produced, which width is predetermined by the machine control unit. The jaw  20  which is subjected in the meantime to a negative pressure holds the end section of the strip which reaches up to the slot  22  and is sucked against the strip contact surface and is advanced in the strip transport direction synchronously to the strip transport via the compressed air cylinder  20 . 1  (shown in  FIG. 2   a ) by at least the width of the film strip in order to keep the strip taut. As already mentioned, the transfer apparatus  23  has been advanced in the meantime via the cylinder of drive  23 . 3  in  FIG. 3  into the plane of the glass pane  60  (cf.  FIG. 4 ). After the negative pressure has been removed, the jaw  20  moves back to the position as shown in  FIG. 3  and also the transfer apparatus  23 . The strip contact surface both of the clamp  20  and the transfer apparatus  23  is subjected to a negative pressure. At the same time, the clamp  21  moves in the direction of clamp  20  until there is contact of the plastic buffers with the edges of the strip  2 . In the next step the knife  30  severs a film strip from the strip  2  which now adheres to the strip contact surface of the transfer apparatus  23 . The knife  30  and the clamp  21  then return to their illustrated initial positions. 
       FIG. 4  shows a glass pane  60  on which a spacer  50  has been placed so as to adhere with its one lateral surface. The spacer  50  comprises a corner joint  50 . 2  between its vertical leg  50 . 1  and its horizontal leg  50 . 3 . The corner joint is to be sealed via the severed film strip  2 . 3  in a diffusion-tight manner. The glass pane  60  rests as usual with its surface averted from the spacer  50  against a supporting wall (not shown), but it could also lie on a horizontal table surface. 
     In the next step, the transfer apparatus  23  with the severed and sucked-in film strip is advanced via the cylinder  23 . 3  to the position as shown in  FIG. 4  rectangular to the plane of the positioned glass pane  60  and thereafter displaced via a cylinder  23 . 4  in the direction of the leg  50 . 1  of the spacer  50 , so that the film strip  2 . 3  adheres with its lower section of its adhesive layer  2 . 1  on the leg  50 . 1 . 
     The width of the surface of the transfer apparatus  23  which holds the film strip  2 . 3  in a sucked manner is at most equal to the width of the narrowest spacer  50 , so that the apparatus can also be used for lager widths without exchanging the transfer apparatus. In the example of  FIG. 4 , the width of the spacer is larger than the width of the above surfaces of the transfer apparatus. 
     Because the transfer apparatus protrudes upwardly beyond the corner joint  50 . 2  according to the length of the film strip  2 . 3  and in order to ensure pressing over the entire surface of the film strip against the vertical leg  50 . 1 , the entire apparatus according to  FIGS. 5   a  and  5   b  comprises a pressure apparatus  70  whose pressure surface is at least equal to the width of the widest used spacer. 
     In the step as shown in  FIGS. 5   a  and  5   b , the transfer apparatus  23  is retracted to its initial position (as shown in  FIG. 3 ). It has thus created space for the pressure apparatus  70  which has been omitted in the preceding Figs. for reasons of improved illustration and which is advanced via a compressed air cylinder  70 . 1  to the respective position which previously was assumed by the transfer apparatus  23  (see  FIG. 4 ). As is shown in  FIG. 5   b , the pressure apparatus  70  therefore presses the respective (lower) section of the film strip against the leg  50 . 1  of the spacer. The upper surface  70 . 2  of the pressure apparatus  70  is in alignment with the upper or outer surface of the leg  50 . 3  of the spacer  50 . A pressure carriage  80  is situated above the pressure apparatus  70 , but in the same plane as the same. It is displaceable vertically by a cylinder  80 . 1  and horizontally by a cylinder  80 . 2  and is used to wrap the part of the film strip  2 . 3  which previously protruded freely over the corner joint  50 . 2  about the corner and to press the same against the leg section  50 . 3  of the spacer  50 . 
     According to  FIGS. 6   a  and  6   b , the pressure carriage  80  comprises a smoothing plate  80 . 3  for this purpose which can be lowered onto the leg  50 . 3  via compressed air cylinder (not shown) arranged in a carriage body  80 . 4  and is bent in the manner of a skid at its end preceding in the direction of movement. The smoothing plate  80 . 3  compresses at first the corner joint  50 . 2  during the lowering to an unavoidable residual gap and smoothes the outer surface of the spacer leg  50 . 3  in the course of the horizontal displacement via the cylinder  80 . 2 . Moreover, the pressure carriage  80  comprises a pressure roller  80 . 5  which trails with respect to the smoothing plate  80 . 3 , which pressure roller, in the course of the displacement of the pressure carriage  80  via cylinder  80 . 2 , performs at first the wrapping of the portion of the film strip  2 . 3  protruding over the edge and then its taut rolling against the leg  50 . 3 . 
     With the pressing of the two sections of the film strip  2 . 3  against the respective leg sections, the surface areas  2 . 1  (see  FIG. 4 ) which are acrylic for example being to polymerize and thus ensure that after the placement of the glass pane (not shown) and the further known production steps the inner space of the finished insulating glass pane is gas-tight also in the area of the corner  50 . 2  and especially remains sealed so as to be prevent diffusion of water vapor. Especially favorable results are achieved when the adhesive  2 . 1  comprises a central strip comprising butyl which then lies precisely over the corner joint and overlaps the corner. 
     After the step shown in  FIGS. 6   a  and  6   b , the described parts return to their respective initial position, so that after the removal of the glass pane  60  and the delivery of the next glass pane and the new position of the described entire apparatus in case of a different pane format the corner joint of the spacer of the next glass pane can be sealed. 
     Having described exemplary embodiments of the invention, it is believed that other modifications, variations and changes will be suggested to those skilled in the art in view of the teachings set forth herein. It is therefore to be understood that all such variations, modifications and changes are believed to fall within the scope of the present invention as defined by the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.