Abstract:
Flexible surface structures ( 21, 22, 27 ) are often glued to one another with the application of pressure and heat. Known laminating devices for this purpose are limited in their efficiency. If greater laminating efficiency is to be achieved, an existing laminating device has to be exchanged for a more powerful laminating device. The invention proposes a laminating device constructed in modular fashion and having a plurality of successive laminating stations ( 12, 14 ). In this way, the laminating efficiency can be increased by adding new laminating stations ( 12, 14 ) to already existing laminating stations ( 12, 14 ) which thus do not need to be replaced. In addition, it is proposed that a drying station ( 17 ) be provided between successive laminating stations ( 12, 14 ), in which drying station the surface structures ( 21, 22 ) laminated in the first laminating station ( 12 ) are dried before they are joined with a further surface structure ( 27 ) in the succeeding second laminating station ( 14 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a method for joining preferably flexible surface structures. 
     The invention relates to joining flexible surface structures by gluing. For the gluing, an adhesive mass is used which generally itself has the form of a surface structure. However, it is also conceivable that the adhesive mass should be already allocated in some other manner to one or a plurality of the surface structures to be joined. 
     The gluing takes place by the application of heat and pressure, the adhesive mass, plasticised by the heat, partially penetrating into the surface structures to be joined and thus effecting the bond between same. In technical jargon, this type of joining of surface structures is also referred to as laminating. 
     The surface structures in question are generally textile surface structures. However they can also be surface structures made of some other nonwoven material, for example foils, nets or mats. The surface structures to be joined are generally present in web form. However it is also conceivable that at least some of the surface structures should be processed already cut to size. 
     Devices for joining flexible surface structures are known which have a single laminating station with two circulating conveyor belts, the surface structures to be joined being conveyed between the facing bights of the conveyor belts through the laminating station. In the region of the laminating station, there is located a heating station by means of which the adhesive mass is activated and the surface structures to be joined are heated up. Following the heating station there is a pressing device, with which the surface structures to be joined are pressed together, the previously plasticised adhesive mass penetrating at least partially into the surface structures to be joined. 
     The known laminating stations only permit limited laminating efficiency. If greater laminating efficiency is required, a correspondingly larger and more powerful laminating station must be used whose laminating capacity is in many cases not fully exploited. This leads to uneconomic operation of laminating stations of this type. 
     SUMMARY OF THE INVENTION 
     Proceeding from this, the purpose underlying the invention is to create a method and a device for joining, especially laminating, flexible surface structures, by means of which flexible and yet economic operation is guaranteed. 
     According to this, method the joining of the surface structures takes place in the course of a plurality of stations which succeed one another in the conveying direction and/or in the direction of handling. Through the arrangement of the stations in succession, it is possible to configure same as independent units, by which means the method makes it possible to form a laminating line for joining the surface structures, which meets the requirements. The individual stations make it possible for the laminating line to be extended as needed, and this makes possible increased efficiency of the same whilst using previous stations. 
     As a development of the method, provision is made for reducing at least the moisture content of some surface structures, between successive thermal treatments in corresponding stations (laminating stations). This is possible in particular as a result of the arrangement in succession, according to the invention, of individual, preferably independent, stations, by corresponding space being formed between the stations, which is necessary in order to remove moisture or the like from at least some of the surface structures to an adequate extent, before these surface structures are preferably treated thermally in the next station. 
     Provision is also made for at least one station, especially a station following after a first station, optionally to be operated in such a way that the surface structures are either warmed or cooled or both warmed and cooled by it. By this means, the laminating line composed of the successive stations, obtains further improved flexibility, because a station of this sort (or even a plurality of stations), which is not currently needed for warming up the surface structures, can be used to increase efficiency by cooling the surface structures which are joined together by laminating. 
     According to a further development of the method, at least one surface structure is supplied between successive stations. This surface structure then does not run through the previous station or a plurality of stations placed in front of it. In this way, surface structures of different sensitivity can be processed and if necessary different joining techniques can be used. 
     According to an advantageous further development of the method, provision is made for taking the web-like surface structures out of engagement with the or each conveyor belt between at least two stations. The outer sides of the textile surface structures lie exposed between successive stations. This is favourable to cooling and evaporation of the surface structures treated in the previous station. In particular, effective reduction in the moistness of the surface structures lying exposed between successive stations is possible in this way. 
     According to the method, provision is additionally made for ascertaining the tension of at least one of the web-shaped surface structures between two successive stations. On the basis of the tension of at least one surface structure ascertained between successive stations, the conveying speed of the surface structures can be so controlled that the tension of the web of the textile surface structure is adjusted to the adhesive mass in such a way that the latter can penetrate the surface structures to sufficient depth. In addition, compression and smoothing effects of the web-shaped surface structure can be achieved through the web tension. 
     According to the device of the invention, through the fact that at least two successive, independent laminating stations are provided according to the invention, it is possible to extend the device as needed. If the full capacity of the device is not needed, one laminating station can remain switched off, which produces a saving in energy. 
     According to a preferred development of the device, a drying station is disposed at least between two successive laminating stations. This drying station can be simply accommodated between the individual successive laminating stations. Moreover, drying the surface structures leaving a laminating station improves the efficiency of a following laminating station. In addition to this, higher processing speeds can be achieved by the successive, sectional laminating with drying steps interspersed, such that the laminating efficiency with successive laminating stations is higher than that with a laminating station having the same capacity as the individual successive laminating stations. 
     Preferably only one conveyor belt, preferably a lower one, is present in the region of the drying station. By this means, the surface structures are uncovered on their upper side, such that moisture can be removed effectively from them in the drying station. The efficiency of the drying station can be further increased if, in the region of same, according to an advantageous development of the invention, the flexible surface structure is deflected away from the lower conveyor belt. Then the web-shaped surface structures (or even just a single web-shaped surface structure) are free on both sides, which permits more efficient dehumidification and vaporisation in the region of the drying station. 
     According to a further advantageous development of the device, a measuring station is provided between at least two laminating stations which succeed one another at a spacing. The measuring station serves to ascertain the tensile force of the web consisting of at least one surface structure, preferably of a plurality of surface structures which are already glued to one another, and if necessary to alter it in such a way that the web is transported at least through the next laminating station with a certain internal tension, which serves especially to smooth the plasticised adhesive mass and to control the depth to which it penetrates into the surface structures. 
     The measuring station is preferably formed from three rollers running at a spacing parallel to one another and which are disposed on a common laminating station securely in the region of the measuring station between two successive laminating stations. Two rollers are preferably configured as guide rollers, between which the third roller, configured as a measuring roller is disposed, in such a way that it moves the web of the surface structures out of the plane of the two outer guide rollers. In this process, a bearing force is generated on the bearings of the measuring roller, which is detected and passed on to a device, preferably a micro-computer or the like, the device controlling, in dependence on the measuring values detected on the measuring roller and the pre-determined web tensions, the succeeding laminating station, especially in respect of the conveying speed of the surface structures. 
     According to a preferred development of the device, the measuring station is allocated to the drying station between two successive laminating stations, the guide rollers of the measuring station especially serving simultaneously to deflect the web of the textile surface structure away from the lower conveyor belt, such that the web lies exposed on both sides. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments, given by way of example, of the device and method according to the invention, are explained in greater detail below with the aid of the drawing. In this the figures show: 
     FIG. 1 a diagrammatic side view of the device, 
     FIG. 2 an enlarged detail II from FIG. 1 in the region of a drying station between two successive laminating stations. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The device shown here relates to a laminating line for gluing together at least partially web-shaped flexible surface structures. The gluing of the surface structures takes place with the application of heat and pressure through a plasticised adhesive mass, which can be supplied to the surface structures to be joined, if necessary also as a web-shaped surface structure. These surface structures can be both textile surface structures and also nonwoven surface structures, for example foils, nets or mats. 
     The laminating line shown here has a take-off station  10 , succeeded by, in the treatment direction, especially in the laminating direction  11 , a first laminating station  12 , a second take-off station  13 , a second laminating station  14 , an air-cooling station  15  and a take-up station  16 . 
     A drying station  17  is disposed between the successive laminating stations  12  and  14 , approximately in the region of the second take-off station  13 . 
     The laminating line, shown here by way of example, has in the region of the first take-off station  10 , three supply rolls  18 ,  19 ,  20 , from each of which a web-shaped surface structure is uncoiled in the laminating direction  11 . The supply rolls  18  and  20  have the external surface structures  21  and  22  which are to be joined. From supply roll  19 , a central surface structure  23  is uncoiled which is preferably the web-shaped adhesive agent for gluing the outer surface structures  21 ,  22 . This central surface structure  23 , after gluing together the outer surface structures  21  and  22 , merges into same, is therefore thereafter practically no longer present as a separate surface structure  23  between the outer surface structures  21  and  22 . 
     In the embodiment shown, two additional supply rolls  24 ,  25  are allocated to the second take-off station  13  between the successive laminating stations  12  and  14 , and from these additional rolls two further web-shaped surface structures  26  and  27  may be drawn. The external surface structure  27 , coming from supply roll  25 , can be of a type that can be additionally glued to the surface structures  21  and  22 . This gluing takes place by means of the surface structure  26  coming from supply roll  24 , which can again be a web-shaped adhesive material. Surface structure  26  also loses its independent nature after surface structure  27  has been glued to surface structure  22 , by, as it were, breaking up between surface structures  22  and  27 . The second laminating station  14  therefore leaves one laminate web  28  out of the three surface structures  21 ,  22  and  27  which have been joined to one another. This laminate web  28  is taken up in the take-up station  16  on a supply roll  29 . 
     The two laminating stations  12  and  14  are, on the laminating line shown here, configured substantially identical. The structure of the first laminating station  12  is described below. This description is also applicable to the second laminating station  14 , identical reference numbers being used for identical parts. 
     The laminating station  12  has a lower conveyor belt  30  and an upper conveyor belt  31 . The upper conveyor belt  31  only extends over a portion of the length of the lower conveyor belt  30 . In the embodiment shown, the upper conveyor belt  30  covers slightly more than half the length of the lower conveyor belt  31 . The lower conveyor belt  30  projects on a feed side  32 , lying in front in the direction of lamination  11 , in relation to the upper conveyor belt  31 . On a runout side  33  of the laminating station  12 , lying behind in the direction of lamination  11 , the ends of the upper conveyor belt  31  and of the lower conveyor belt  30  lie approximately above one another. Preferably, both conveyor belts  30  and  31  are driven synchronously, the web-shaped surface structures, here surface structures  21 ,  22  and  23 , being here conveyed between the facing bights of the lower conveyor belt  30  and of the upper conveyor belt  31  through the laminating station  12 . 
     The laminating station  12  has in its interior, approximately along a portion of the shorter upper conveyor belt  31 , a heating device  34 , which is succeeded by a pressing device  35  in the direction of lamination  11 . The heating station  34 , the pressing device  35  and also the remaining design of the laminating station  12  are known as such, for example from DE 35 02 608 C2 and DE 42 15 028 C2. 
     The second laminating station  14  is disposed behind the first laminating station  12  in such a way that the lower (longer) conveyor belt  30 , projecting on the feed side  32  in relation to the upper (shorter) conveyor belt  31 , succeeds the lower conveyor belt  30  of the first laminating station  12 . The lower conveyor belts  30  of the two laminating stations  12  and  14  thus form a continuous conveying distance for the surface structures  21 ,  22  and  23 . Because the upper conveyor belt  31  is shorter, between the successive laminating stations  12  and  14  there is a region in which the surface structures  21 ,  22  and  23  are not covered on their upper side, i.e. lie exposed. In this region, i.e. on the feed side  32  of the second laminating station  14 , is located the drying station  17 . on the device shown here, there is associated with the drying station  17  simultaneously the second take-off station  13  and a measuring station  36  (FIG.  2 ). 
     The measuring station  36  is located approximately in the middle between the ends of the upper conveyor belt  31  and the lower conveyor belt  30  of the first laminating station  12  and of the upper conveyor belt  31  of the second laminating station  14 . The measuring station  36  is formed from three parallel rollers running transversely to the direction of lamination  11 . These are two outer guide rollers  37 ,  38  and a measuring roller  39  disposed in the middle between same. Opposite ends of the guide rollers  37 ,  38  and of the measuring roller  39  are mounted in a fixed frame of the measuring station  36 , this frame not being shown in FIG.  2 . Preferably, the longitudinal central axes of the guide rollers  37 ,  38  and of the measuring roller  39  lie in a common horizontal plane. Only the surface structures  21 ,  22  and  23  coming from the first laminating station  12  pass through the measuring station  36 , in such a way that the surface structures  21 ,  22  and  23  run along over the guide rollers  37 ,  38  but pass the central measuring roller  39  on the lower side. In this way, the web of the surface structures  21 ,  22 ,  23  is deflected from the measuring roller  39  roughly in a triangular shape out of its plane between the guide rollers  37 ,  38 , as a result of which the tension of the web of the surface structures  21 ,  22 ,  23  brings an upwardly directed reaction force to bear on the measuring roller  39 . This is detected on at least one bearing of the measuring roller  39  by a corresponding force transducer. 
     Each force transducer of the measuring roller  39  is connected with a control system of at least the second laminating station  14 , in such a way that the measurement signals of each transducer of the measuring roller  39  is converted in the control system into signals which correspond to the tensile stress of the web of the surface structures  21 ,  22 ,  23 . In this way, the control system of at least the second laminating station  14  receives information about the current tension in the web of the surface structures  21 ,  22 ,  23  in the measuring station  36 . This web tension can be made to conform with a desired web tension recorded in the control system, by the control system monitoring the drive of the upper conveyor belt  31  and of the lower conveyor belt  30  of the second laminating station  14  and setting or adjusting its speed correspondingly. 
     The measuring station  36  in conjunction with a corresponding control or regulating system for the drive speeds of the conveyor belts  30  and  31  of the second laminating station  14  make it possible to set the treatment of surface structures  21 ,  22 ,  23 ,  26  and  27 , which takes place in this laminating station, individually to the respective adhesive agent and to the material of the surface structures  21 ,  22  and  27  which are to be joined. In addition to this, special compression and smoothing effects of the surface structures  21 ,  22  and  27  can be achieved. 
     The longitudinal central axes of the guide rollers  37 ,  38  and of the measuring roller  39  are disposed with such spacing above the upper bight of the upper conveyor belt  31  of the second laminating station  14 , that neither the guide rollers  37 ,  38  nor the measuring roller  39  are adjacent to the upper bight of the upper conveyor belt  31 ; rather, a gap occurs between the guide rollers  37 ,  38  and the measuring roller  39  and the upper bight of the upper conveyor belt  31 . In this gap is disposed, below the guide rollers  37 ,  38  and the measuring roller  39 , a collecting trough  40  for fluid or the like dripping from the surface structures  20 ,  22 ,  23  in the region of the measuring station  36 . 
     Through the fact that the guide rollers  37 ,  38  and the measuring roller  39  are arranged at a spacing above the upper conveyor belt  31 , in the measuring station  36  the web of the surface structures  21 ,  22 ,  23  is raised from the guide rollers  37 ,  38  and the measuring roller  39  away from the upper bight of the lower conveyor belt  30  of the second laminating station  14 , such that in the region of the upper conveyor belts  31 , succeeding one another at a spacing, of the laminating stations  12  and  14 , the web of the surface structures  21 ,  22 ,  23  is exposed on both sides which means that a finish can be vaporised and moisture can escape. The escaping moisture and finish is led away by an extraction hood  41  above the feed side  32  of the second laminating station  14  which is left free in the region of the drying station  17  by the upper conveyor belts  30 . 
     After the measuring station  36 , but before the upper conveyor belt  31  of the second laminating station  14 , there are disposed deflection rollers  42  from which the web-shaped surface structures  26  and  27 , which are uncoiled from the supply rolls  24  and  25  of the second take-off station  13 , are led from above to the web of the surface structures  21 ,  22  and  23  which have already been laminated in the first laminating station  12 . The two surface structures  21  and  22  then run into the feed side  32  of the second laminating station  14  along with the surface structure  23  which has broken up between surface structures  21  and  22  during the previous lamination in the laminating station  12 , as well as the surface structures  26  and  27  supplied before the second laminating station  14 . 
     After leaving the second laminating station  14 , the finished laminate web  28  is cooled in the air-cooling station  15  and rolled up onto the supply roll  29  in the take-up station  16 . 
     The web tension in the first laminating station  12  can be controlled or adjusted by unrolling the surface structures  21 ,  22  and  23  in the first take-off station  10 . similarly, the web tension of the finished laminate web  28  in the drying station  17  behind the second laminating station  14  can be controlled or adjusted by the take-up speed of the laminate web  28  on the supply roll  29  in the take-up station  16 . 
     The invention is suitable for laminating lines which have more than two laminating stations and where more than two surface structures may be glued at the same time in the laminating stations. As an alternative to the method described above, it is also possible with the laminating station according to the invention to glue together surface structures which have been cut to size. 
     Finally, it is also possible to imagine providing between two or more than two successive laminating stations with either a measuring station or a drying station, or only a measuring station or only a drying station. Where there are more than two successive laminating stations it is also conceivable not to arrange a drying station and/or a measuring station between all the successive laminating stations. 
     The method according to the invention works with the device described above substantially as follows: 
     The webs of the outer surface structures  21  and  22  which are to be joined together, coming from the first take-off station  10 , and of the surface structure  23  lying between same and having the adhesive mass serving to glue the surfaces, run in the laminating direction  11  on the feed side  32  into the first laminating station  12 . The surface structures  21 ,  22  and  23  are transported between the facing bights of the conveyor belts  30  and  31  through the first laminating station  12  and in so doing are heated up in the heating device  34  and glued to one another in the pressing device  35 , namely laminated. In this process, the central surface structure  23  serving to supply the adhesive agent breaks up into surface structures  21  and  22  by the adhesive agent partially penetrating these surface structures  21  and  22  and thus joining them together. with same. on the runout side  33 , thus practically only a partially finished laminate web consisting of the outer surface structures  21  and  22 , joined to one another, leaves the first laminating station  12 . This partially laminated web then runs through the drying station  17  with the measuring station  36  behind the first laminating station  12  and in front of the second laminating station  14 . 
     Because the upper conveyor belts  31  of the laminating stations  12  and  14 , disposed behind one another, succeed one another at a spacing, the upper side of the partially finished laminate web, consisting of the surface structures  21  and  22 , is exposed in the region of the drying station  17  and the measuring station  36 . In addition to this, in the region of the measuring station  36 , the partially finished laminate web, consisting of the surface structures  21  and  22 , is deflected from the guide rollers  37  and  38  and the measuring roller  39  and is also deflected away from the lower conveyor belt  30  of the second laminating station  14 , namely raised in relation to the upper bight of the lower conveyor belt, as a result of which the lower side of the partially finished laminate web consisting of the surface structures  21  and  22  lies exposed. Thus, in the region of the drying station  17 , on the laminate web of the surface structures  22  and  23 , exposed on all sides, the finish and moisture can at least partially escape and be led away via the extraction hood  41  or via the collecting trough  40  in liquid and/or gas form. Because the partially finished laminate web is lifted from the lower conveyor belt  30 , no condensation can form on the latter. Thus the surface structures  21  and  22 , as they run into the second laminating station  14 , can be embedded between dry conveyor belts  30  and  31 . Moreover, the surface structures  26  and  27 , supplied from the second take-off station  13  and still untreated, can be brought together with dry surface structures  21  and  22 . This bringing together of the surface structures  26  and  27 , supplied at the second take-off station  13 , with the surface structures  21  and  22  which have already been glued together in the first laminating station  12 , takes place between the measuring station  36  and the feed side  32  of the second laminating station  14 , at the deflection rollers  42 . In this process, the surface structure  26 , serving to supply the adhesive agent, comes to rest on the upper side of the surface structure  22 . Above surface structure  26  with the adhesive agent, there is located the surface structure  27  which is to be joined to surface structures  21  and  22  subsequently in the second laminating station  14 . 
     The measuring station  36  detects the tension of the web-shaped surface structures  21  and  22  between the laminating stations  12  and  14 . To this end, measuring signals detected at the force transducers of the measuring roller  39  are converted by a computing device of the control system into signals which are proportional to the web tension, and compared with the web tension recorded in the control system. Through corresponding control or adjustment of the speed of the conveyor belts  30  and  31  of the second laminating station  14 , the web tension of the surface structures  21  and  22  between the laminating stations  12  and  14  can be brought to a pre-determined value which corresponds to requirements. 
     The separate laminating stations  12  and  14  make it possible to apply different temperatures to the surface structures in the heating devices  34 . In particular it is possible in the first laminating station  12  to apply higher temperatures to the surface structures  21 ,  22  and  23  than in the second laminating station  14 . By this means, surface structures  26  and  27  which are more sensitive to temperature can be processed in the second laminating station  14 . For this reason, the device is generally operated in such a way that the heating device  34  of the first laminating station  12  works with higher temperatures than the heating device  34  of the second laminating station  14 . 
     The first laminating station  12  is, if the surface structures  21  and  22  to be glued in it permit this, operated at as high a temperature as possible in the heating device  34 , in order to speed up the vaporising of finish and moisture in the surface structures  21 ,  22  and  23  in the following drying station  17 . Here, the temperature in the heating device  34  is chosen to be such that only after the surface structures  21 ,  22  and  23  have run through the pressing device  35  do they begin to emit moisture and the finish. The vaporising between the laminating stations  12  and  14  leads, moreover, to the fact that at least the surface structures  21  and  22  in the second laminating station  14  have a minimal residual moisture which guarantees effective lamination of surface structures  21  and  22 , especially of surface structure  22 , with the (third) surface structure  23  which is only supplied in front of the second laminating station  14 . In addition, the reduced moisture in the surface structures  21  and  22  makes possible gluing in the second laminating station  14  at reduced temperatures, by which means surface structures  27  which are sensitive to temperature can be glued in the second laminating station  14 .