Abstract:
A method for assembling a window sash having an integrated insulating glass pane. The window sash has a frame formed from plastic hollow profile sections. The frame has an inner face, an outer face facing away from the inner face, and two flanks that connect the inner face and the outer face to each other. On the inner face thereof, the frame has two webs parallel to each other, which constitute an all-round delimitation of the window opening of the window sash and are adhesively secured to two glass panes which are held spaced apart by the two webs.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage application of International Application No. PCT/EP2010/005577, filed on Sep. 11, 2010, which claims priority of German patent application number 10 2009 048 641.0, filed on Sep. 30, 2009, both of which are incorporated herein by reference in their entireties. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the field of assembling window sashes. More specifically, the present invention relates to a method for assembling a window sash having an integrated insulating glass pane. 
     2. Description of the Prior Art 
     The invention starts at a method comprising the features specified in the preamble of patent claim  1 , namely, a method for forming a device for assembling window sashes comprising an integrated insulating glass pane, wherein the window sashes comprise a frame formed from plastic hollow profiles comprising an inner face, an outer face facing away from the inner face, and two flanks which connect the inner face and the outer face to each other, wherein the frame, on the inner face of the frame comprises two webs which are parallel to each other, which constitute an all-around delimitation of the window opening of the window sash and which are adhesively secured to two glass plates which are held spaced apart by the two webs. Such a method is known from U.S. Pat. No. 6,286,288 B1 and from U.S. Pat. No. 7,097,724 B2 for producing sliding sashes. These publications disclose window sashes for sliding sashes and methods for the production thereof, which are known under the identification “sashlite”. 
     In the case of the “sashlite” method, a rectangular or square frame is initially formed from an extruded plastic hollow profile, in that the four legs of the frame are cut from the plastic hollow profile and are welded to each other in pairs at their ends by means of ultrasound for forming the corners of the frame. On its inner face, the frame has two webs, which are parallel to each other. A paste-like adhesive compound, in which a moisture-binding material, in particular molecular sieves in the form of powder, is embedded, is injected into the space between these two webs. A line of a sealing and adhesive compound, by means of which two glass plates are adhesively secured to the two webs, which serve as spacers for the two glass plates, is applied all around, at all four legs of the frame, on the outside of the two webs. Such a sealing and adhesive compound will hereinbelow be referred to as sealing compound. It has the object of establishing a fixed connection between the webs of the frame, which are directed inwardly, and the glass plates, and to seal the gap between the webs and the glass plates against the penetration of moisture and against a loss of a heavy gas, which is possibly filled into the space between the glass plates. 
     The pre-manufactured frame is placed onto a horizontal conveyor track and is conveyed to a processing station, in which the adhesive compound, which includes the moisture-binding material, is initially injected into the space between the two webs at all four legs of the frame. Said space is open towards the respective opposite leg of the frame. A line of the sealing compound is then applied to the one of the two webs, which is located on the top, and a first glass plate is adhesively secured thereto. The frame is then turned over on the horizontal conveyor track, so that the web having the first glass plate, which adheres thereto, is located on the bottom and the second one of the two parallel webs is located on top. A line of the sealing compound is then applied all around to the web, which is now located on top, and the second glass plate is adhesively secured to this line. 
     Outside of the area, which is covered by the glass plates, one of the two webs has a bore, which leads into the space between the glass plates. The space between the two glass plates can be vented by means of this bore when the two glass plates are pressed against the webs, whereby the space between the glass plates is decreased. The pressing of the glass plates takes place in that, e.g., rollers act on the glass plates in the area of the two webs and the glass plates are pressed against the webs through this, whereby the sealing compound is flattened and the gap between the two glass plates is sealed. It is known as another possibility for pressing the two glass plates of a sashlite window against the two webs of the window frame, to suck air from the space between the two glass plates through the bore, which is provided in one of the webs, so that a low pressure, which pulls the glass plates against the webs and thus flattens the sealing compound, is created in the space. 
     In the case of the sashlite method, it is furthermore known to insert two small tubes into the bore in one of the two webs of the window frame. A heavy gas, e.g. argon, is blown through one of the small tubes into the space between the two glass plates. Air or a mixture of air and the heavy gas is extracted from the space between the two glass plates by suction through the other small tube. Through this, the air in the space between the glass plates is partially replaced with the heavy gas, whereby the heat transfer between the two glass plates is made difficult. After such a gas exchange, the bore in the web of the frame is sealed. 
     Lastly, cover strips, which cover the edge of the glass plates towards the outside, are also inserted into the frame. The window sash having the integrated insulating glass pane is thus finished. 
     For the most part, the known sashlite method is carried out manually. It is disadvantageous that the personnel costs are high and that quality deficiencies are unavoidable. 
     The instant invention has the object of remedying this. 
     SUMMARY OF THE PRESENT INVENTION 
     The method according to the invention is the subject matter of patent claim  1 . Advantageous refinements of the method are the subject matter of the subclaims. 
     The method according to the invention for assembling a window sash having an integrated insulating glass pane, which has a frame formed from plastic hollow profiles, said frame having an inner face, an outer face facing away from the inner face, and two flanks, which connect the inner face and the outer face to each other, wherein, on its inner face, the frame has two webs, which are parallel to each other, which constitute an all-around delimitation of the window opening of the window sash and are adhesively secured to two glass plates, which are held spaced apart by means of the two webs, takes place by
         setting up the frame and the glass plates in a vertical position or in a position, which is inclined by a few degrees against the vertical,   injecting by machine a paste-like adhesive compound, in which a moisture-binding material is embedded, into the space between the two webs,   applying by machine a continuous line of a sealing compound onto the two outer faces of the webs, which face away from each other,   orienting and holding by machine the two glass plates and the frame such that the two glass plates are located opposite each other so as to be congruent or almost congruent and so that the frame stands between the two glass plates and is oriented such that the glass plates and the edges of the two webs are centered towards each other, and   pressing by machine the two glass plates against the webs facing them.       

     Preferably, the set-up of the frame and of the glass plates in vertical position or in a position, which is inclined by a few degrees against the vertical, also takes place machine-based. 
     This has considerable advantages:
         The set-up of the frame and of the glass plates in vertical position or in a position, which is inclined by a few degrees against the vertical, and the carrying out of the operating steps, which lead to an assembled window sash, in such a position is a basic principle for a considerable rationalization of the assembly method.   Personnel costs are saved.   The operating steps, which have to be carried out, are independent on individual weaknesses and errors of the operating personnel.   The quality of the window sashes is increased considerably and leads to a considerable lengthening of the operating life of the insulating glass pane in the window sash.       

     Preferably, the glass plates and the frame are set up on a horizontal conveyor and are secured against falling over. The processing on a horizontal conveyor is a basic principle for attaining a high productivity. 
     By means of horizontal conveying, the glass plates and the frame are preferably first brought into a position, in which they are located next to each other and in which the vertical edges of the glass plates and of the two webs of the frame are centered to each other in conveying direction, while the lower edges of the glass plates and of the frame are still located in a common plane. Only then the glass plates are lifted relative to the frame and the frame is lowered relative to the glass plates, until the horizontal edges of the glass plates and of the two webs of the frame are centered relative to each other. By this, the glass plates and the frame can be conveyed for all of the preparatory work and up to the first phase of the actual assembly with their lower edge being at the same height, even though the lower edge of the glass plates in the finished window sash must be located above the lower edge of the frame. This measure has the advantage that it facilitates the set-up of an automatically operating production line and shortens the processing times. 
     For centering the horizontal edges of the glass plates and of the webs of the frame relative to each other, the glass plates are preferably held in particular by means of suction devices, which act on the sides of the glass plates facing away from each other. The horizontal conveyor with the frame standing thereon can then be lowered and the height of the glass plates can then be oriented correctly to the frame for the window sash. The joining of the glass plates to the frame then takes place immediately by means of adhesion, so that orientation errors must no longer be feared. 
     During the lowering of the frame, the upper horizontal leg of the frame is caught with its inner face preferably by an adjusting device, which adjusts the position of the upper leg of the frame prior to pressing the glass plates against the webs of the frame facing them. With this measure, a disadvantageous sagging of the upper leg of the frame can be compensated in particular in the case of large-sized window sashes. Preferably, the glass plates are conveyed by means of a first horizontal conveyor via a turnout into a preparation station, which has three conveyor tracks, which are located parallel next to each other, which together can be displaced transversely and the two outer conveyor tracks of which are intended for the two glass plates and the middle conveyor track of which is intended for the frame of the window sash. Initially, the two outer conveyor tracks in the preparation station are consecutively brought into alignment with the conveyor track of the turnout, so that the two glass plates are conveyed on the two outer conveyor tracks of the preparation station. Preferably, the frame of the window sash is conveyed by means of a second horizontal conveyor, which is provided next to the first horizontal conveyor, only after this. A turnout is to connect the preparation station to the second horizontal conveyor, after it has supplied the two glass plates to the preparation station. The turnout then takes over the frame for a window sash and pivots back into alignment with the horizontal conveyor of the preparation station, which, by means of lateral displacement, brings its middle conveyor track in alignment with the conveyor track of the turnout or with the first horizontal conveyor, respectively, when the turnout has not yet been pivoted back into alignment with the first horizontal conveyor. The frame is then conveyed into the space between the two glass plates in the preparation station. This has the advantage that the sealing compound, which is typically applied onto the frame while being hot and which is preferably a reactive hotmelt, is brought in contact with the two glass plates within the shortest possible delay, so that a proper adhesion can be attained. From the preparation station, the two glass plates and the frame located therebetween, are together conveyed into an assembly station following the preparation station, in which they are centered to each other and the glass plates are pressed against the webs of the frame. 
     The first horizontal conveyor preferably connects a washing machine for the glass plates to the turnout. Arriving from the storage and being cut to size, the glass plates can thus be placed onto the production line. They are only washed at that location, so that the best conditions for also reaching the assembly station in a clean state are at hand. 
     A first station is preferably assigned to the second horizontal conveyor, wherein in the first station the paste-like adhesive compound, in which a moisture-binding material is embedded, is injected into the space between the two webs of the frame. A station, in which the continuous line of the sealing compound is applied onto the two outer faces of the webs facing away from each other, is also assigned to the second horizontal conveyor. Preferably, this takes place only after the paste-like adhesive compound, in which a moisture-binding material is embedded, has been applied. This also contributes to the time period between the application of the hot sealing compound to the final assembly of the window sash being as short as possible. For the same reason, the sealing compound is also simultaneously applied to the two webs. 
     The provision of two separate horizontal conveyors, which are connected to the preparation station and the assembly station by means of a turnout, also contributes to the time period between the application of the sealing compound to the actual assembly being as short as possible. In addition, the throughput through the production line is increased considerably. 
     When the insulating glass pane, which is integrated into the window sashes, is to contain a heavy gas, this is preferably attained in that one of the two glass plates is bent away from the frame prior to pressing against the webs of the frame, so that between the bent glass plates and the web located opposite thereto at least an access to the space between the two glass plates remains open after the glass plates have been pressed against the webs. A heavy gas can then be filled into the space between the glass plates through this access. The bending of the glass plate is then reversed, whereby the space between the two glass plates is closed tightly. This course of action can be automated in a particularly advantageous manner in the production line. It additionally has the advantage that considerably higher degrees of filling levels are attained with it than with the known sashlite method and that the danger of leakiness, which can lead to a loss of heavy gas and to a permeation of moisture, is smaller than in the case of the sashlite method, because in the case of the sashlite method a separate bore in the frame is provided for the gas filling, which bore must be closed subsequently. Such a bore is a permanent weak spot. According to the invention, such a bore is avoided. 
     Preferably, the one glass plate is bent away from the frame for the gas filling at two corners, which are located diagonally opposite each other. This is particularly advantageous for a quick filling process and for a high degree of filling. 
     Preferably, the one glass plate is bent with the help of suction devices, which are disposed on the outer face of the glass plate. This measure combines a gentle mode of operation with a desired fixation of the glass plate in predetermined position. 
     During the joining of the glass plates and of the frame, the glass plates are preferably pressed against the webs of the frame in that two frameworks, at which the suction devices are attached, are moved closer together. A defined path, by which the glass plates are displaced, is thus possible while being controlled well. In addition, the suction devices can contribute to a certain cushioning of the assembly process. During the assembly, the glass plates are preferably cushioned by means of thrust plates, which are acted upon by a compressed air cylinder and simultaneously act onto both glass plates in the area of the edge of the glass plates. In this manner, the compressed air cylinders can act as pneumatic spring, which prevents the breaking of glass and simultaneously provides for an optimal adhesive connection, in particular when a preselected pressure acts on the compressed air cylinders of the thrust plates for reaching an even pressing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An exemplary embodiment of the invention will be specified below by means of the enclosed drawings. 
         FIG. 1  shows, in top view, a first section of an assembly line for window sashes having an integrated insulating glass pane, 
         FIG. 2  shows a top view of a second section of the assembly line for window sashes having an integrated insulating glass pane, 
         FIG. 3  shows the preparation station from  FIG. 1  in a transversal view, 
         FIG. 4  shows the preparation station from  FIG. 3  in a side view with viewing direction parallel to the conveying direction, 
         FIG. 5  shows the section A from  FIG. 4  as detail, 
         FIG. 6  shows section B of from  FIG. 4  as detail, 
         FIG. 7  shows the assembly station from  FIG. 1  in a transversal view, 
         FIG. 8  shows the assembly station in a side view parallel to the conveying direction, 
         FIG. 9  shows the rear part of the assembly station from  FIG. 8  in a front view, 
         FIG. 10  shows the front part of the assembly station from  FIG. 8  in a view seen from the rear part of the device, 
         FIG. 11  shows, as a detail, a transversal view onto the outlet end of the assembly station having a window frame and two glass plates, which are located parallel next to each other, 
         FIG. 12  shows, as detail C, a section of the rear part of the assembly station, 
         FIG. 13  shows, as detail D, a section of the front part of the assembly station, 
         FIG. 14  shows a first section from  FIG. 13 , 
         FIG. 15  shows a second section from  FIG. 13  with changed adjustment, 
         FIGS. 16-18  show three subsequent phases of the assembly of the window sash, illustrated in the area of the upper edge thereof, and 
         FIG. 19  shows a section of a partially assembled window sash having a glass plate, which is bent away, during the gas exchange. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 and 2  show, in a schematic top view, a production line for window sashes or the wings of a door having an integrated insulating glass pane. To simplify matters, only window sashes are discussed in this patent application. However, the same applies to the wings of a door. Wings of a door are to be included in the invention. The term “sash” is to comprise displaceable as well as pivotable sashes. 
     The illustration in  FIG. 2  connects to the right end of the illustration in  FIG. 1 . 
     The production line has a first horizontal conveyor  1  and a second horizontal conveyor  2 , which runs transversely thereto and which lead into a horizontally conveying turnout  4 , to which a third horizontal conveyor  3  connects, which is arranged in alignment with the first horizontal conveyor  1 . The first horizontal conveyor  1  consists of a plurality of sections, starting with a section  5 , to which the individual glass plates  52 ,  53  are placed one after the other, of a section, which leads through a machine  6  for washing and drying the glass plates, and of two sections  7  and  8 , which serve the intermediate transport and, if necessary, also for retaining the glass plates  52 ,  53 . In section  7 , it is furthermore also possible to check whether the washed glass plates are actually clean. In sections  5  to  8 , the first horizontal conveyor  1  has a horizontal row of synchronously driven rollers  9 , which are located in the sections  5 ,  7  and  8  at the lower edge of a support wall  10 , which is inclined backwards against the vertical by few degrees, e.g. by 6°, and which is preferably embodied as an air cushion wall. The glass plates are conveyed while standing on the rollers  9  and leaning against the support wall  10 . The glass plates are supported in the washing and drying machine  6  in an inherently known manner by means of an arrangement of washing brushes and rollers. 
     The second horizontal conveyor  2  also has a plurality of sections  11 ,  12 ,  13 ,  14  and  15 , in which provision is made in each case for a continuous conveyor belt  16  comprising a horizontally running upper run at the lower edge of a support wall  17 , which is inclined backwards out of the vertical position at the same angle as the support wall  10 . Advantageously, the upper run is arranged at a right angle to the support wall  10  and is thus also inclined backwards by a few degrees. The second horizontal conveyor  2  serves to convey rectangular or square frames  51  (see  FIG. 1 ), which are formed from plastic hollow profiles. They are placed onto the conveyor belt  16  with one of their legs and are leaned against the support wall  17 , in which strips, which are preferably provided with bristles, in particular with soft bristles, for reducing the friction, are inserted or adhesively secured. A row of free-running guide rollers  18 , which are partially located beneath the support wall  17 , but which project beyond it and which in each case have an axis, which runs vertically to the upper run of the conveyor belt  16 , is located closely above the conveyor belt  16 . Provision is preferably made at a distance to the support wall  17  for a further row of support rollers  19 , the height of which can be adjusted and which, if necessary, serve to prevent a tilting of the frame standing on the conveyor belt  16 . 
     In section  11  of the second horizontal conveyor  2 , the frames formed from the plastic hollow profiles  21  are placed onto the horizontal conveyor  2 . 
     A system  20  is assigned to the section  12  of the second horizontal conveyor  2 , which system  20  serves to inject an adhesive compound, in which a desiccant is embedded, into the space between two webs of the plastic hollow profile, from which the frame  51  for the window sash is formed. An example of such a plastic hollow profile is illustrated in cross section in  FIGS. 16 to 19 . The illustrated plastic hollow profile  21  has a plane outer face  22 , a structured inner face  23 , two flanks  24  and  25  and several hollow chambers. Two webs  26  and  27 , which are parallel to the flanks  24  and  25  and parallel to each other and the space between which is open towards the inner face of the frame  51 , are located on the inner face  23 . The webs  26 ,  27  are angled at their free end and thus form a projection  28 , against which the glass plates  52 ,  53  can hit, for which the webs  26  and  27  serve as spacers, see  FIG. 18 . An adhesive compound  29 , in which a desiccant is embedded, is injected into the space between the webs  26  and  27  by means of the system  20 . A polyisobutylene is particularly suitable as adhesive compound  29  and molecular sieves are particularly suitable as desiccant. Advantageously, the adhesive compound  29  is injected by means of a nozzle  30 , which can be displaced up and down parallel to the support wall  17  and which can be rotated about an axis, which is perpendicular to the support wall  17 . For injecting the adhesive compound  29  into the space between the vertical webs  28 , the nozzle  30  is moved up or down, respectively, while the frame  51  formed from the hollow profile  21  rests. The adhesive compound  29  is injected into the space between the horizontal webs  26  and  27 , while the frame  51  formed from the hollow profile  21  is conveyed back or forth horizontally, respectively, and the nozzle  30  rests. 
     A system  31  for applying a line  35  of a sealing compound to the faces of the webs  26  and  27 , which face away from each other, is assigned to the section  14  of the second horizontal conveyor  2 . For this purpose, a first nozzle  32  is located in front of the support wall  17  and a second nozzle  33  is located behind the support wall  17 , from where it can engage through the support wall  17  through a slot  34  therein, which runs from the bottom to the top. The nozzles  32  and  33  can be moved in the same manner as the nozzle  30  and they are moved and activated synchronously, so that they simultaneously apply the sealing compound to the outer face of the two webs  26  and  27 . The line  35  of the sealing compound is illustrated in  FIGS. 16 to 18 . 
     The sections  13  and  15  of the second horizontal conveyor  2  serve for the intermediate transport of the frames. If necessary, lattice bars can be inserted into the frame  51  in section  13 . 
     The section of the production line illustrated in  FIG. 1  starts with the turnout  4 , which can be pivoted back and forth between the two positions illustrated in  FIG. 1 . The turnout  4  has a horizontal conveyor with a design, which is the same as or which is similar to one of the sections of the second horizontal conveyor  2  and which can thus be considered to be a pivotable continuation of the second horizontal conveyor  2 . In the position, in which the turnout  4  is aligned with the first horizontal conveyor  1 , it can take over the glass plates  52 ,  53 , which have been conveyed to that location, and can transfer them into a preparation station  36 . In the position, in which the turnout  4  is aligned with the second horizontal conveyor  2 , it can take over a frame  51  for the window sash from said second horizontal conveyor  2 . To be able to transfer the frame  51  into the preparation station  36 , the turnout  4 , however, must initially be pivoted into that position, in which it is aligned with the preparation station  36  and the first horizontal conveyor  1 . 
     The preparation station  36  is illustrated in  FIGS. 3 to 6 . It has a frame-shaped framework  39  on a subframe  37 , which has two rails  38 , which are inclined backwards. On its front face, the framework  39  has two posts  40 , which are inclined backwards and which project upwards at a right angle to the rails  38 . The rails  38  run at a right angle to the conveying direction of the first and third horizontal conveyor  1  or  3 , respectively. The posts  40  are inclined backwards at the same angle as the support walls  10 . An arrangement of three horizontal beams  41 ,  42  and  43  is supported at the posts  40  so as to be displaceable up and down, so that the height of the beams  41 ,  42  and  43  can be adjusted. The three beams  41 ,  42  and  43  in each case support a horizontal row of free-running support rollers  44 , which can be rotated about axes, which run parallel to the posts  40 . A three-track horizontal conveyor  45 , which encompasses a horizontal support  46  for three continuous conveyor belts  47 ,  48  and  49 , the upper runs of which are arranged parallel to each other at a distance and which are inclined backwards at the same angle as the posts  40 , is attached to the framework  39  in the lower area thereof. The two outer conveyor belts  47 ,  49  serve to convey glass plates  52 ,  53 , whereas the middle conveyor belt  48 , which is wider than the outer conveyor belts  47  and  49 , is intended to convey a frame  51  for a window sash. The conveyor belts  47  to  49  can be driven separately. On the support, free-running support rollers  50  are arranged on both sides of the conveyor belts  47  and  49 . They serve the purpose of guiding the lower edge of the glass plates and of the frame for the window sash. The axes thereof run parallel to the axes of the rollers  44 , which are attached to the beams  41 ,  42  and  43 . 
     By transversely displacing the framework  39  on the rails  38  of the subframe  37 , each of the three conveyor belts  47 ,  48  and  49  can be brought into alignment with the horizontal conveyor of the turnout  4 . In the position illustrated in  FIG. 1 , the turnout  4  can transfer a frame  51  for a window sash to the middle conveyor belt  48 ; the support rollers  18  of the turnout  4  are aligned with the support rollers  50 , which are arranged between the rear conveyor belt  49  and the middle conveyor belt  48 , and which are inclined backwards at the same angle as the posts  40 . To transfer a glass plate  53  to the rear conveyor belt  49 , the latter is positioned by transversely displacing the support  46  such that the support rollers  50  arranged behind the conveyor belt  49  are aligned with the support rollers  18  in the turnout  4 . To be able to transfer a glass plate  52  to the front conveyor belt  47 , the latter is positioned by transversely displacing the support  46  such that the support rollers  50  arranged between the front conveyor belt  47  and the middle conveyor belt  48  are aligned with the support rollers  18  in the turnout  4 . 
     In the preparation station  36 , the frame  51  and the two glass plates  52  and  53  are preferably positioned such that the front vertical edges thereof are located approximately next to each other and are adjacent to the subsequent assembly station  54 . 
     The assembly station  54  is illustrated in  FIGS. 7 to 15 . It has a subframe  55  comprising rails  56 , the incline of which corresponds to the incline of the rails  38  in the preparation station  36 . A framework  57  is attached to the subframe  55 , which framework  57  is similar to the framework  39  of the preparation station  36  and, as does the latter, has an arrangement of three beams  58 ,  59 , and  60 , to which a horizontal row of support rollers  61  is attached in each case, the axes of which run approximately vertically, namely at a right angle to the rails  56 . As in the case of the arrangement of the beams  41  to  43  in the preparation station  36 , the arrangement of the beams  58  to  60  is attached at the posts of the framework  57  in a height-adjustable manner. In contrast to the displaceable framework  39  in the preparation station  36 , the framework  57 , however, is fixed on the subframe  55  so as not to be able to be displaced. A three-track horizontal conveyor  62 , the design of which corresponds to the three-track horizontal conveyor  45  in the preparation station  36 , is attached to the subframe  55  so as to be height-adjustable. 
     A front framework  63 , which can be displaced on a pair of rails  56 , is arranged in front of the stationary framework  57 . A rear framework  64 , which can also be displaced on a pair of rails  56 , is arranged behind the stationary framework  57 .  FIG. 2  shows a view of the rear framework  64 . At their lower ends, two lateral posts  65  of the rear framework  64  have undercut guide parts  66 , which engage around the rails  56 . At the posts  65 , a horizontal traverse  67  is attached, which can be displaced up and down at the post  65  by means of gear belts  68 , which are driven by a motor  69 . Thrust plates  70  are attached to the traverse  67 , which thrust plates  70  can be activated by means of pressure medium cylinders  71 , in particular by means of pneumatic cylinders, which are illustrated in  FIGS. 7 and 8 , but which are not visible in  FIG. 9 , because they are located behind the traverse  67 . Provision is made above each thrust plate  70  for an adjusting device  72 , see  FIG. 16 , consisting of a pneumatic cylinder  73 , the piston rod  74  of which has a head  75 , to which a retractable bar  76 , which is guided parallel to the piston rod  74 , is attached. The adjusting device  72  serves the purpose of positioning the upper leg of the frame  51  and to remove a possible sagging of the upper leg of the frame  51 , see  FIGS. 16 to 18 . 
     Thrust plates  70 , which are also individually activated by means of pressure medium cylinders, and additionally a row of suction devices  78  are attached to a lower traverse  77  of the rear framework  64 . A further suction device  78  is attached to the horizontal traverse  68 . The suction devices  78  as well as the thrust plates  70  can be displaced individually by means of pressure medium cylinders  89 , in particular by means of pneumatic cylinders. An upright traverse  80 , which is parallel to the posts  65 , is attached to the lower traverse  77  and to an upper traverse  79  of the rear framework  64 , so as to be displaceable horizontally. The upright traverse  80  crosses the horizontal traverse  67  and is arranged behind the latter. The displacement of the upright traverse  80  takes place in the same manner as in the case of the horizontal traverse  67  by means of two gear belts  81 , which are driven by a motor  82 . Further thrust plates  70  and  70   a , which can also be activated individually by means of pressure medium cylinders, are attached to the upright traverse  80  and to the post  65 , which is parallel thereto. Most of the thrust plates  70  are attached to the traverses  67 ,  77  and  80  as well as to the post  65 , in each case on a slide  83 , which drags along smaller thrust plates  70   a , which are attached to a slidable lattice grate  84 , whereby the distance of the thrust plates  70 ,  70   a , which are connected by the slidable lattice grate  84 , from each other changes. The length adjustment effected by the slidable lattice grate  84  allows for the position of the thrust plates  70  and  70   a  to be optimally adapted to the height and width of the frames  51 . The displaceability of the traverses  67  and  80  also serves for the adaptation to height and width of the frames  51  for the window sashes. 
       FIG. 9  furthermore shows two suction devices  85  and  86 , which are larger than the suction device  78 . In the view of  FIG. 9 , the lower suction device  85  is located in the left lower corner of the field defined by the traverses  67 ,  77 ,  68  and by the post  65  and is attached to the lower traverse  77 . The upper suction device  86  is located in the diagonally opposite corner of this field. While the lower suction device  85  can only be moved back and forth and otherwise maintains its position at the lower traverse  77 , the upper suction device  86  can additionally follow the movements of the traverses  67  and  80 , so that it maintains its position in the corner of the field, which is determined by the position of the traverses  67  and  80 . A glass plate  53 , which is held by the suction devices  78  in the field, which the traverses  76 ,  70 ,  68  and the post  65  span, can be bent backwards at two diagonally opposite corners by means of these suction devices  85  and  86 . In addition, the larger suction devices  85 ,  86  contribute to the fixing of the glass plates  52 ,  53 , which must take place before the three-track horizontal conveyor  62  can be lowered. The larger suction devices  85  and  86  can be displaced by means of pressure medium cylinders, in particular by means of pneumatic cylinders  89  in the same manner as the smaller suction devices  78 . 
     With the help of the larger suction devices  85  and  86 , an access to the space between the two glass plates  52 ,  53  of the window sash can be held open temporarily during the assembly of a window sash for the purposes of a gas exchange. Air in the space between the glass plates  52  and  53  is replaced with heavy gas during the gas exchange. Advantageously, the heavy gas is supplied in the area of the lower corner in the vicinity of the lower suction device  85  and displaces the air through the opening in the area of the upper suction device  86  located diagonally opposite thereto. So that the heavy gas does not discharge again through the access, which is held open by the lower suction device  85 , provision is made at that location for a two-legged seal  87 , which covers the gap between the frame  51  and the rear glass plate  53  in the lower corner of the frame  51  and thus seals the access to the space between the glass plates  52 ,  53 . The seal  87  can be a molded part, e.g. consisting of a foam rubber or the like. A feed line  88  for the heavy gas, which is to be supplied, extends through the seal  87 . The end section of the feed line  88 , which is guided through the seal  87 , is preferably a porous pipe piece, the end of which is closed, which can consist, e.g., of a sintered plastic, from which the heavy gas escapes in a diffuse manner, flows into the space between the glass plates  52 ,  53  and displaces the air at that location upwards such that the air leaves the space via the opening provided by the upper suction device  86 . 
       FIG. 10  shows a view of the front framework  63 , which corresponds to the view of  FIG. 9 , which is arranged in front of the three-track horizontal conveyor  62  in the assembly station. This front framework  63  is substantially a mirror image of the rear framework  64 , so that reference can be made to the description of the rear framework  64  with reference to the details. The front framework  63 , however, does not have the larger suction device  85 , the seal  87  and also not a feed line  88  for a heavy gas. 
     The window sashes are assembled in the described production line according to the following method: 
     The two glass plates  52  and  53  required for a window sash are placed onto section  5  of the first horizontal conveyor  1 . The frame  51  required for the window sash, which is pre-manufactured from plastic hollow profiles, is placed onto section  11  of the second horizontal conveyor  2 . The glass plates  52  and  53  are conveyed consecutively through the washing and drying machine  6 , can be checked for cleanliness in section  7  of the first horizontal conveyor  1 , reach section  8  of the first horizontal conveyor  1 , on which they can be stored, if necessary, when the turnout  4  or the preparation station  36  following it should not yet be ready. The turnout  4  is ready for the glass plates  52  and  53  when it is aligned with the first horizontal conveyor  1  and when it is empty. In this case, the two glass plates  52  and  53  are conveyed consecutively onto the turnout  4 . When the preparation station  36  is ready, it is positioned by means of lateral displacement such that either the support rollers  50  arranged behind the rear conveyor belt  49  or the support rollers  50  arranged between the front conveyor belt  47  and the middle conveyor belt  48 , are aligned with the support rollers  18  of the turnout  4 . In the last-mentioned case, the first glass plate  52  is then conveyed on the front conveyor belt  47 , is conveyed by it just in front of the outlet end of the preparation station  36  and is stopped there. By transversely displacing the framework  39 , the conveyor track intended for the second glass plate  53  with the rear conveyor belt  49  is then displaced to be aligned with the turnout  4  and the turnout  4  conveys the second glass plate  53  to the rear conveyor belt  49 , which conveys it up to the outlet end of the preparation station  36  and stops it there. The three-track horizontal conveyor  62  is subsequently positioned such that its middle conveyor track comprising the wider conveyor belt  48  is aligned with the first horizontal conveyor  1 . 
     Overlapping in time with the passage of the two glass plates  52  and  53  through the first horizontal conveyor  1 , the adhesive compound, in which a desiccant is embedded, is injected into the space between the two webs  26  and  27  of the frame  51  on the second horizontal conveyor  2  in section  12  thereof. If desired, it is possible to insert lattice bars into the frame  51  in section  13  of the second horizontal conveyor  2 . In the subsequent section  14  of the second horizontal conveyor  2 , a continuous line  35  of a sealing compound is applied to the outer face of the two webs  26  and  27  without interruption. In the subsequent section  15  of the second horizontal conveyor  2 , the frame  51 , which is prepared and coated in this manner, can be stored until the turnout  4  is free and is pivoted into its position, which is aligned with the second horizontal conveyor  2 . The frame  51  is subsequently conveyed onto the turnout  4 . As soon as this has taken place, the turnout  4  pivots back into alignment with the first horizontal conveyor  1 . If this has not taken place until then, by transversely displacing on the subframe  37 , the framework  39  of the preparation station  36  with the line of support rollers  50  arranged between the middle conveyor belt  48  and the rear conveyor belt  49  is next brought into alignment with the support rollers  18  in the turnout  4 . As soon as this has taken place, the frame  51  is conveyed onto the middle conveyor belt  48  and is further conveyed by it to the outlet end of the preparation station  36 . If the subsequent assembly station  54  is ready for take-up, the frame  51  can run into the assembly station  54  without stopping and the two glass plates  52  and  53  are simultaneously conveyed out of the preparation station  36  into the assembly station  54 . In the event, however, that the assembly station  54  is not yet ready, the frame  51  is stopped in the preparation station  36 . The frame  51  and the glass plates  52  and  53  have then assumed the position illustrated in  FIG. 1 . As soon as the assembly station  54  is ready, the frame  51  and the two glass plates  52  and  53  are simultaneously conveyed into the assembly station  54  and are moved into the proximity of the outlet end thereof, where they are stopped—e.g. controlled by means of position sensors—such that the upright edges of the two glass plates  52 ,  53  in conveying direction are centered towards the upright edges of the two webs  26  and  27  of the frame  51 . Due to the fact that the upper runs of the conveyor belts  47 ,  48  and  49  are located in a common plane, the height of the glass plates  52  and  53  is not yet correctly oriented towards the height, which they must assume in the frame  51 , see  FIG. 11 . 
     To attain this, the suction devices  78  provided in the two frameworks  63  and  64  of the assembly station  54  are pushed ahead up to the adjacent glass plate  52  or  53 , respectively, by activating pneumatic cylinders  89 , at the piston rod of which in each case a suction device  78  is attached and activated, so that the two glass plates are aspirated and are fixed in their position. Only those suction devices  78 , which are required for the length and height of the respective glass plates  52  and  53 , are pushed forward and activated. The dimensions of the glass plates  52 ,  53  can be known from the production planning and can be provided by the control of the assembly station  54 , or they can be determined by position sensors, which are provided in the assembly device  54 . In this manner, the traverses  67  and  80  can be automatically adjusted to the current dimensions of the glass plates  52 ,  53  or to the corresponding frame  51 , respectively. The adjustment of the traverses  67  and  80  to the dimensions of the current frame  51  includes the orientation of the thrust plates  70 ,  70   a , for the purpose of which the slides  83  are displaced into such a position, in which the thrust plates  70 ,  70   a  are located opposite to the edge of the glass plates  52  and  53  at distances, which are as even as possible. Only suction devices  78  are activated, which are located in the field, which, in terms of  FIG. 9 , is located on the bottom left and is defined by the traverses  66 ,  67  and  80  as well as by the post  65 . In addition, the larger suction devices  85  and  86  are pushed forward against the glass plates  52  and  53  and are activated. 
     Simultaneously with the suction devices  78 , the thrust plates  70 ,  70   a  are also extended by their pneumatic cylinders  71  and come in contact to the glass plates  52 ,  53 , see  FIG. 16 . In addition, the adjusting device  72  is now activated. For this purpose, the bars  76  are extended by activating the pneumatic cylinders  73 , so that they reach underneath the flanks  24  and  25  of the upper leg of the frame  51 , see  FIG. 16 . 
     The three-track horizontal conveyor  62  can now be lowered in the assembly station  54 . Through this, the upper leg of the frame  51  is placed onto the bars  76 , see  FIG. 17 , and a possible sagging of the upper leg of the frame  51  is overcome. The three-track horizontal conveyor  62  is lowered until the horizontal edges of the glass plates  52  and  53  are centered on the horizontal edges of the webs  26  and  27 . The lines  35  of the sealing compound are now located opposite to the glass plates  52 ,  53  close to the edge thereof. 
     Next, the beams  58 ,  59  and  60  are lifted, so that the support rollers  61  disengage from the glass plates  52 ,  53 . The front framework  63  and the rear framework  64  are then both moved towards each other, whereby the glass plates  52  and  53  press against the line  35  of the sealing compound, which is located on the webs  26  and  27 . The movement of the frameworks  63  and  64  is thereby cushioned by the pneumatic cylinders  71  of the thrust plates  70 ,  70   a , which ensure a pressing of the glass plates  52 ,  53  against the webs  26  and  27  of the frame  51  at a predetermined pressure, see  FIG. 18 . 
     The window sash is thus assembled. The pneumatic cylinders of the thrust plates  70 ,  70   a  and of the adjusting device  72  retract their piston rods again, the suction devices  78 ,  85  and  86  are deactivated and pulled back, the three-track horizontal conveyor  62  is lifted back to the original height, which corresponds to the height of the horizontal conveyor in the preparation station  36 , and the window sash is conveyed out of the assembly station  54  onto an outlet conveyor  90 . If necessary, cover strips, which cover the edge of the glass plates  52  and  53 , can be inserted here into the frame  51  in a manner, which is known per se. 
     In the event that the insulating glass pane, which is integrated into the window sash, is to be filled with a heavy gas, this takes place in that, prior to the pressing of the one glass plate  53  against the frame  51 , the rear glass plate  53  is bent outwards at diagonally opposite corners by means of the suction devices  85  and  86 —see  FIG. 19 —wherein the heavy gas is introduced through the access, which has been established by means of the suction device  85  and air is displaced from the space between the two glass plates  52  and  53  through the opening, which has been established by means of the suction device  86 . Once a sufficiently high filling degree of the heavy gas has been reached, the suction devices  85  and  86  are deactivated, whereby the openings close easily due to the elastic resilience of the glass plates  52  and  53  and are closed by the impact of the pneumatically activated thrust plates  70 ,  70   a .  FIG. 19  shows in detail the access  91  at a lower corner of the window sash with the attached seal  87  and a section of the porous feed line  88 , through which the heavy gas is supplied, and a part of the elastomeric suction plate of the suction device  85  between the seal  87  and the glass plate  53 . 
     What has been described above are preferred aspects of the present invention. It is of course not possible to describe every conceivable combination of components or methodologies for purposes of describing the present invention, but one of ordinary skill in the art will recognize that many further combinations and permutations of the present invention are possible. Accordingly, the present invention is intended to embrace all such alterations, combinations, modifications, and variations that fall within the spirit and scope of the appended claims.