Abstract:
An application apparatus is for applying a liquid or pasty medium to a moving base. The moving base is a surface of a material web in a case of direct application and a surface of a transfer element for transferring the medium to the material web in a case of indirect application, the material web being one of paper and cardboard. The application apparatus has an inlet side and an outlet side with respect to a direction of movement of the moving base. The application apparatus includes a carrying beam; an essentially rigid supporting unit provided on the carrying beam; a sealing doctor device positioned at the inlet side of the application apparatus, the sealing doctor device being fixedly attached to the supporting unit; and a metering doctor device positioned at the outlet side of the application apparatus, the metering doctor device being fixedly attached to the supporting unit. The sealing doctor device and the metering doctor device define an application chamber therebetween.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the invention. 
     The present invention relates to an apparatus for the application of a liquid or pasty medium to a moving base. 
     2. Description of the related art. 
     A base for the application of a liquid or pasty medium, in the case of direct application, is the surface of a fiber material web, in particular of paper or cardboard. Alternatively, in the case of indirect application, the surface of a transfer element, for example a transfer roll, transfers the medium to the material web, the medium being brought into contact with the moving base in an application chamber. The application chamber is bounded on the inlet side by a metering doctor device, with respect to the running direction of the base with the two doctor devices being arranged on a carrying beam. 
     An application apparatus of this type is disclosed, for example, by DE 44 44 779 A1. In the case of this application apparatus, the metering doctor device bounding the application chamber on the outlet side is designed as a roll doctor, whose doctor bed is fixed directly on the carrying beam via a holding blade. In order to influence the setting of the metering doctor against the base in accordance with the operation, an actuating device is provided. On the inlet side, the application chamber is likewise bounded by a roll doctor device, the doctor bed accommodating the doctor rod being fixed to a carrier beam by a spring-loaded holder. Specific influence of the setting of the sealing doctor rod against the base is not possible during the continuous operation of the application apparatus. Because of the above-described holding of the doctor devices by flexible blades, the distance between the two roll doctors can vary slightly, which entails a corresponding variation in the volume of the application chamber. Consequently, the medium has to be fed to the application chamber with a high excess in order to ensure in the application chamber pressure relationships which permit a reproducible coat weight of the medium leaving the application chamber of the application layer to be obtained. 
     The same is also true of the application apparatus disclosed by EP 0 319 503 B1 (see, in particular, FIG. 10) and the application apparatus disclosed by DE 84 14 904 U1. The two last-mentioned application apparatuses additionally have the disadvantage that the doctor bed or the blade holder of at least one of the two doctor devices is also used at the same time for bounding the feed line for feeding the medium into the application chamber. On the one hand, this creates sealing problems and, on the other hand, when the setting of the respective doctor device against the moving base is changed, it also inevitably leads to an influence being exerted on the quantity of medium fed to the application chamber per unit time (medium feed rate). Such an influence further has a detrimental effect on the pressure relationships prevailing in the application chamber. 
     In addition, DE 196 52 289 A1 discloses an application apparatus of the generic type in which both the sealing doctor device and the metering doctor device are a doctor rod. The two doctor rods are accommodated in a common doctor bed, in which the feed line for the medium is also located. The feed line is fixed to the carrying beam via an elastic blade. Furthermore, two actuating devices are provided, one of which acts on the doctor bed in the region of the sealing doctor rod and the other acts in the region of the metering doctor rod. Although, in the case of this application apparatus, on the one hand the size of the application chamber and on the other hand the quantity of medium fed per unit time depend to a lesser extend on the setting of the two doctor devices against the base. The disadvantage with this arrangement is that a change in the influence of one of the two actuating devices on the doctor bed always leads to an influence being exerted on the setting of the respective other doctor device against the moving base, so that coat weight and excess quantity cannot be adjusted independently of each other. 
     For completeness, reference should further be made to DE 29 13 053 A1 in relation to the prior art. 
     SUMMARY OF THE INVENTION 
     By contrast, the present invention specifies an application apparatus of the generic type which, while maintaining the capability of independently exerting an influence on the setting of the two doctor devices against the moving base, makes it possible to obtain defined volume and/or pressure relationships in the application chamber. 
     According to the invention, an application apparatus of the type mentioned at the beginning uses two doctor devices which are fixed to an essentially rigid supporting unit provided on the carrying beam. On account of the essentially rigid construction of the supporting unit, the doctor devices are kept at a predetermined distance from each other in the running direction of the base. On account of the rigidity~of the supporting unit, this predetermined distance is, in this case, essentially independent of the quantity of medium fed to the application chamber per unit time, the pressure prevailing in the application chamber and the respective setting of the two doctor devices against the base. Furthermore, the essentially rigid supporting unit ensures a defined arrangement of the two doctor devices in the transverse direction of the base as well. Overall, in this way, the conditions prevailing in the application chamber and medium feed, in particular volume and/or pressure, can be reproduced so reliably that the excess quantity which leaves the application chamber past the sealing doctor device can be reduced considerably, as compared with the prior art and, consequently, a high-quality application layer can be obtained. As a result of reducing the excess quantity, the circulated quantity of the medium can be reduced, and thus the delivery pump assigned to the medium feed can be designed to have a correspondingly lower performance and therefore to be more cost-effective in procurement and operation. 
     Moreover, the essentially rigid supporting unit permits the two doctor devices to be fixed to it in such a way that their settings against the moving base can be influenced independently of each other, without a change to the setting of one of the two doctor devices which would otherwise result in back-effects on the setting of the respective other doctor devices. The resulting decoupling of the two doctor devices simplifies their driving and thus increases their adjustment potential. This can be achieved, for example, by making it possible for the two doctor devices to be fixed to the supporting unit independently of each other. 
     In a development of the invention, it is proposed that the supporting unit include feed channels which feed the medium from a distribution pipe to the application chamber. In this way, the influence exerted on the quantity of medium fed to the application chamber per unit time can be decoupled largely, if not completely, from the influence exerted on the setting of the two doctor devices against the base. For example, the feed channels can be constructed as through holes, bores or the like in the supporting unit. Alternatively, the feed channels could also run through at least one of the doctor devices, for example through a doctor bed of a roll doctor device. In particular in the case of an application apparatus with a relatively low operating width and/or an application apparatus for applying medium at a relatively low coat weight, it may be advantageous for the distribution pipe also to be formed in the supporting unit. This simplifies, at least, the construction of the carrying beam. 
     In order to be able to achieve the most uniform possible distribution of the medium emerging from the feed channels in the transverse direction of the base, that is to say over the operating width, it is proposed that at least one baffle plate be arranged on the supporting unit in the area of the outlet openings of the feed channels into the application chamber. This baffle plate prevents the medium emerging from the feed channels from immediately contacting with the base, and thus ensures the deflection of the medium both in the running direction and in the transverse direction of the base. Here, the movement components in the transverse direction ensure uniform distribution of the medium over the operating width, while the movement components in the running direction prevent the production of transverse vortices which have a detrimental influence on the application result. 
     The distance between the baffle plate and the outlet openings and/or the shape of the baffle plate can be chosen on the basis of the operating conditions with regard to exerting a favorable influence on the resulting application. The distance between the baffle plate and the outlet openings can, in this case, be changed, for example, by fixing the baffle plate detachably to the supporting unit and interposing appropriate spacers. 
     A simple and nevertheless precise type of attachment of the doctor devices to the supporting unit can be provided, for example, by fixing the metering doctor device and/or the sealing doctor device to the supporting unit in a form-fitting manner. 
     For attachment to the supporting unit, at least one of the two doctor devices can be assigned at least one force appliance, which is preferably supported on the supporting unit or on a part connected thereto. Furthermore, at least one of the two doctor devices, preferably both thereof, can respectively be assigned at least one force appliance for exerting an influence on its setting against the moving base. This setting force appliance can also be supported on the supporting unit or on a part connected thereto. 
     The sealing doctor device mainly has the function of sealing off the application chamber against the ingress of air. That is to say, in particular, to keep away from the application chamber an air boundary layer carried along at the surface of the moving base. Thus, with regard to the simplest possible design of the control unit of the application apparatus according to the invention, it is sufficient for the setting of the sealing doctor device against the moving base to be capable of being adjusted without closed-loop control. On the other hand, since the metering doctor device is used to set the magnitude of the coat weight of the medium applied to the moving base, it is advantageous if the setting of the metering doctor device against the moving base can be controlled. 
     Both the at least one fixing force appliance and the at least one setting force appliance can be force appliances which can be operated hydraulically and/or pneumatically and/or hydropneumatically and/or electrically and/or magnetically and/or by electric motor and/or electrochemically. 
     With regard to the ability to change the transverse profile of the layer of medium applied to the base, it is further proposed that at least one of doctor devices, preferably at least the metering doctor device, be assigned a number of force appliances which are arranged adjacently in the transverse direction of the base and which can be driven and/or controlled independently of one another, and thus permit an influence to be exerted section by section on the setting of the doctor device against the base. 
     In order to prevent contamination of the force appliances and thus be able to ensure their serviceability, in a development of the invention it is proposed that a flat covering element be provided between at least one of the doctor devices and at least one of the force appliances assigned to this doctor device. The use of a covering element of this type is advantageous, in particular in the area of the sealing doctor device, since in order to avoid the ingress of air into the application chamber, it is quite common to feed the medium to the application chamber in excess and to permit excess medium to emerge from the application chamber past the sealing doctor device in the direction opposite to the running direction of the base. 
     In a manner known per se, the metering doctor device and/or the sealing doctor device may include a doctor rod. In this case, the metering doctor rod and/or the sealing doctor rod can be driven in rotation. In particular, a metering doctor rod rotating in the direction opposite to the running direction of the base can improve the quality of the resulting application. 
     In a development of the invention, it is proposed that the diameter of the metering doctor rod be alternately equal to or smaller than the diameter of the sealing doctor rod. 
     Furthermore, the two doctor rods can either have a smooth or a profiled surface; however, in order to achieve a good sealing action, it is advantageous if at least the sealing doctor rod has a profiled surface. 
     In principle, the supporting unit can be provided as an integral part of the carrying beam. If, however, the supporting unit is a unit constructed separately from the carrying beam, then the carrying beam ensures the stability of the application apparatus with regard to bending effects caused by gravity. Thus, the supporting unit itself does not need to perform any stabilization function and can therefore be constructed as a part which has a relatively light weight and therefore be simple to handle. The supporting units can be fixed to the carrying beam at a relatively low number of fixing points, which simplifies the machining of the carrying beam. 
     Furthermore, the low number of fixing points of the supporting unit on the carrying beam permits the rapid changing of the supporting unit and the doctor devices arranged on it. Thus, during the continuous operation of the application apparatus, using a first supporting unit with doctor devices arranged thereon, a second supporting unit with unworn doctor devices can be readied at an equipment workplace and then, when the application apparatus is at a standstill, can be substituted relatively quickly and simply for the first supporting unit. Using such a changeover procedure, the unproductive times of the application apparatus can be reduced. 
     If the loading of the sealing doctor device can be controlled indirectly or directly on the basis of the pressure prevailing in the application chamber, this helps to prevent the production of an undesired excess of pressure in the application chamber. Furthermore, it is possible to influence the coat weight of the medium leaving the application chamber as an application layer by the loading of the metering doctor device and sealing doctor device being varied relative to each other. 
     In addition or as an alternative, it is moreover possible for the metering doctor device and/or the sealing doctor device to be a doctor blade. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a schematic illustration of a section, made at right angles to the transverse direction of the moving base, of a first embodiment of an application apparatus according to the invention; and 
     FIGS. 2 and 3 are schematic, sectional illustrations similar to FIG. 1 of further embodiments of an application apparatus according to the invention. 
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate multiple preferred embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE INVENTION 
     In FIG. 1, application apparatus  10  is used to apply a medium  12  as an application layer  14  to a base U moving in the direction of arrow L. Base U can, in the case of direct application, be surface  16   a  of a material web  16 , in particular a paper or cardboard web, or can, in the case of indirect application, be the surface of a mating element, for example a mating roll, from which application layer  14  is then transferred to material web  16 . 
     Application apparatus  10  includes an application subassembly  18 , which is preferably detachably fixed to a carrying beam  20 . Carrying beam  20  is designed in a manner known per se as a solid component. Carrying beam  20  thereby serves to prevent bending, caused by gravity, of entire application apparatus  10  over the operating width of material web  16 . In the embodiment illustrated, distribution pipe  22 , running in transverse direction Q of material web  16 , is also arranged in carrying beam  20  and is used to feed and distribute medium  12  uniformly over the operating width of material web  16 . The construction and arrangement of such distribution pipes  22  are known in the prior art and will therefore likewise not be described in detail here. 
     Application subassembly  18  includes a base unit  24  which, in the embodiment illustrated, includes a supporting element  26  and two abutment elements  28  and  30 . Dividing base unit  24  into three portions merely has the point of simpler production. In particular, abutment elements  28  and  30  can be constructed identically and simply arranged in mirror-image fashion. Alternatively, however, it is also possible to construct base unit  24  in one piece as supporting element  26 . Supporting element  26  and abutment elements  28  and  30  can be produced, for example, from stainless steel. 
     The essentially rigid supporting element  26  performs a number of functions according to the invention. Firstly, it serves to fix two doctor devices, namely a sealing doctor device  32 , which is arranged on the inlet side of supporting element  26 , in reference to running direction L of base U, and a metering doctor device  34 , which is arranged on the outlet side of supporting element  26 . Secondly, supporting element  26  serves to deliver medium  12  from distribution pipe  22  into an application chamber  44 , which is bounded by doctor devices  32  and  34 , an end face  26   a  of supporting element  26  and base U. For this purpose, feed channels  26   b  are formed in supporting element  26 , extend to end face  26   a  from an end face  26   c  of supporting element  26  that rests on carrying beam  20  and, in addition, are connected to passages  22   a , which are formed in distribution pipe  22  or carrying beam  20 . 
     In the embodiment illustrated, both doctor devices  32  and  34  are constructed as roll doctor devices with a doctor rod  36  or  38 , which is accommodated in a doctor bed  40  or  42  such that it can be rotated and, if desired, driven in rotation (see arrow P in the case of metering doctor rod  38 ). Doctor rods  36  and  38  are each smooth (as shown) or profiled. Since doctor devices  32  and  34  are constructed identically to each other in the embodiment illustrated, in the following text the manner of fixing doctor devices  32  and  34  to supporting element  26  will be explained merely using the example of sealing doctor device  32 . 
     In order to fix sealing doctor device  32  to supporting element  26 , doctor bed  40  has an attachment  40   a , which is connected flexibly to a main element  40   b  of doctor bed  40 . A force appliance  46 , in the present embodiment, is a pressure hose  46  which is supported on abutment element  28 . Pressure hose  46  presses attachment  40   a  of doctor bed  40  against a contact face  26   d  on supporting element  26 . In order to facilitate the positioning of doctor bed  40  relative to supporting element  26 , and in order to reliably prevent any relative movement between doctor bed  40  and supporting element  26  in the operating state of application apparatus  10 , additional projections  40   c  provided on attachment  40   a  engage in a form-fitting manner in corresponding depressions  26   e  on contact face  26   d.    
     A further pneumatic hose  48 , which is likewise supported on abutment element  28 , acts on doctor bed  40  in the region of main part  40   b  of the latter. By use of pneumatic hose  48 , due to the flexible connection between main part  40   b  and attachment  40   a  of doctor bed  40  when doctor bed  40  is fixed to supporting element  26 , the setting of doctor rod  36  against base U can be varied. In this connection, it goes without saying that the flexibility of the connection between attachment  40   a  and main part  40   b  of doctor bed  40  can be provided both by suitable material selection and also by suitable constructional design of doctor bed  40 . 
     As already mentioned above, doctor device  34  is fixed to supporting element  26  by a pneumatic hose  50  in the same way as has been explained above for sealing doctor device  32 . Furthermore, metering doctor device  34  is also assigned a further pneumatic hose  52 , which serves to exert an influence on the setting of metering doctor rod  38  against base U. While sealing doctor rod  36  merely has the task of preventing the ingress of air into application chamber  44 , in particular of air which is carried along in the form of an air boundary layer (indicated dashed in FIG. 1) by base U on its surface, metering doctor rod  38  is used for metering medium  12 , which leaves application chamber  44  in the form of application layer  14 , and thus for setting the magnitude of the coat weight of application layer  14 . It therefore goes without saying that the setting of metering doctor rod  38  against moving base U must be capable of being varied considerably more finely by pneumatic hose  52  than the setting of sealing doctor rod  36  by pneumatic hose  48 . This is indicated in FIG. 2 by a control unit  180 . 
     On account of the essentially rigid construction of supporting unit  26 , in the embodiment illustrated in FIG. 1, doctor devices  32  and  34  are kept at a predetermined distance from each other in running direction L of base U. On account of the rigidity of supporting unit  26 , this predetermined distance is in this case, in turn, essentially independent of the quantity of medium  12  fed to application chamber  44  per unit time, the pressure prevailing in application chamber  44  and the respective setting of doctor devices  32 ,  33  against base U. Furthermore, essentially rigid supporting unit  26  ensures a defined arrangement of doctor devices  32  and  34  in transverse direction Q of base U as well. Overall, in this way the conditions prevailing in application chamber  44  and medium feed channels  26   b  can be reproduced so reliably that the excess quantity which leaves application chamber  44  past sealing doctor device  32  can be reduced considerably, as compared with the prior art, and nevertheless a high-quality application layer  14  can be obtained. As a result of reducing the excess quantity, the circulated quantity of medium  12  can be reduced, and thus the delivery pump assigned to medium feed  12  can be designed to have a correspondingly lower performance. 
     In addition, doctor devices  32  and  34  are provided not only as separately constructed subassemblies but also as subassemblies which can be driven independently of each other, so that a change to the setting of one of two doctor devices  32  and  34  against base U by one of force appliances  48  or  52  has no direct back-effect on the setting of the respective other doctor device  32 ,  34  against base U. This simplifies in particular the control or regulation of the setting of metering doctor device  34 , which has a decisive influence on the coat weight and the quality of the resulting application. 
     Moreover, doctor devices  32  and  34  are arranged on a supporting element  26  or base unit  24 , which is constructed separately from carrying beam  20 . But this means carrying beam  20 , which as a solid part is difficult to handle and to machine, needs to have only the fixing points for entire application subassembly  18 . As will be explained in more detail below using further embodiments, not only does this permit the easy conversion of application apparatus  10  from one design type to another, but it also permits, for example in the event of wear, the rapid replacement of a worn application subassembly  18  by a new application subassembly  18  prepared at an equipment workplace. Of course, because of the fixing of doctor devices  32  and  34  to supporting element  26  by force appliances  46  and  50 , the rapid replacement of one or both of doctor devices  32  and  34  is also possible. 
     A further embodiment of an application apparatus  10  according to the invention is illustrated in FIG.  2 . This embodiment essentially corresponds to the embodiment according to FIG.  1 . For this reason, in FIG. 2 similar parts are provided with the same reference symbols as in FIG. 1, but increased by the number  100 . In addition, the application apparatus  110  according to FIG. 2 will be described below only to the extent to which it differs from the embodiment according to FIG. 1, to whose description reference is hereby expressly otherwise made. 
     A first difference between application apparatus  110  according to FIG.  2  and application apparatus  10  according to FIG. 1 is that metering doctor rod  138  of metering doctor device  134  has a smaller diameter than sealing doctor rod  136  of sealing doctor device  132 . The reason for this is based on the fact that, in this case, medium  112  is fed to application chamber  144  in excess, so that the volume flow leaving application chamber  144  past seating doctor rod  136  is greater than the volume flow leaving application chamber  144  past metering doctor rod  138  as application layer  114 . 
     Furthermore, it is pointed out that doctor beds  140  and  142  essentially have the same shape, in particular in the area of their connection to supporting element  126  and to the point of action for force appliances  146 ,  148 ,  150  and  152  (which are illustrated purely schematically as arrows in FIG.  2 ). This makes it possible to fit one and the same supporting element  126  or one and the same base unit  124  supplemented by abutment elements  128  and  130  with doctor rods  136  and  138  of any desired diameter, provided only that doctor beds  140  and  142  for doctor rods  136  and  138  are of identical construction with regard to the above-mentioned contact areas, matching the predefined design conditions of remaining application subassembly  118 . 
     In relation to doctor beds  140  and  142 , it should further be added that the flexibility of the connection of attachment  140   a  to main part  140   b  is assisted by a notch  140   d.    
     Finally, the fitting of doctor beds  140  and  142  in supporting element  126  differs from the corresponding type of fitting in the exemplary embodiment according to FIG.  1 . To be specific, contact face  126   d  in the region of the fitting of application subassembly  118  to carrying beam  120  runs essentially orthogonally to the surface of the latter. 
     A further difference between application apparatus  110  according to FIG.  2  and the application apparatus  10  according to FIG. 1 is that, in the area of the opening of the mouth of feed channels  126   b  into application chamber  144 , there is arranged a baffle plate  160 , which has a predetermined distance d from end face  126   a  of supporting element  126 . For this purpose, baffle plate  160  can be fixed to supporting element  126  for example by bolts  164 , with the interposition of spacers  162 . Baffle plate  160  prevents medium  112  emerging from feed channels  126   b  from coming directly into contact with base U. Instead, medium  112  emerging from feed channels  126   b  is deflected both in running direction L and in transverse direction Q of base U. This leads to a more uniform distribution of medium  112  in transverse direction Q, and thus results in a more uniform coating application. That is to say, a more uniform thickness of application layer  114  in running direction L and in transverse direction Q of base U is produced. 
     By loosening bolts  164  and replacing spacers  162 , it is possible to adapt distance d of baffle plate  160  from end face  126   a  of supporting element  126  to the operating conditions in any desired way, for example, the viscosity of medium  112 , the quantity of medium  112  fed to application chamber  144  per unit time, the diameter of doctor rods  136  and  138  and the like. In a similar way, the shape of baffle plate  160  can be chosen in a suitable way to match it to the operating conditions. 
     A further difference is that distribution pipe  122  in application apparatus  110  according to FIG. 2 is formed in supporting element  126  and not in carrying beam  120 . This is advantageous in particular in the case of application apparatus  110  with a low operating width and/or in the case of application apparatus  110  with which only a low coat weight is applied to base U. Furthermore, in this way the construction of carrying beam  120  is simplified. 
     Finally, application apparatus  110  according to FIG. 2 differs from the embodiment according to FIG. 1 in that, in the area of sealing doctor device  132 , between force appliance  148  for exerting an influence on the setting of sealing doctor rod  136  against base U and doctor bed  140 , there is arranged a covering element  166  which, for example, is fixed to abutment element  128  at  166   a . Covering element  166 , which can be produced from plastic, for example, has the task of protecting force appliance  148  and also force appliance  146  against contamination by medium  112 ′ which leaves application chamber  144  past sealing doctor device  132  in the direction opposite to running direction L of base U. Such a countercurrent of medium  112 ′ can be desirable, for example, in order to be able to prevent the ingress of air into application chamber  144  still more reliably. It should further be noted that covering element  166  is constructed flexibly and/or fixed to abutment element  128 , both in such a way that it does not significantly impede the adjustment of sealing doctor device  132  by force appliance  148 . 
     Although this is not illustrated in FIG. 2, it is of course also possible for a corresponding covering element  166  to be provided in the area of metering doctor device  134  and to protect force appliances  152  and  150  against splashes of medium  112 , such as are possibly formed downstream of metering doctor device  134  in running direction L. 
     In addition or as an alternative to feed channels  126 b running through supporting element  126 , feed channels  127  can also be provided, which pass through a doctor bed  140  or  142  in one of doctor devices  132  and  134 . In FIG. 2, such feed channels  127  are shown dashed only for doctor device  132 , for clarity of illustration. Distribution channel  122 ′ feeding feed channels  127  can be formed between doctor bed  140  and abutment element  128  or, as in the embodiment illustrated, between doctor bed  140  and covering element  166 . 
     FIG. 3 illustrates a further application apparatus according to the invention, which essentially corresponds to the two application apparatuses described above. Therefore, in FIG. 3 analogous parts are provided with the same reference symbols as in FIG. 1, but increased by the number  200 . Furthermore, the embodiment according to FIG. 3 is described below only to the extent to which it differs from the embodiments according to FIGS. 1 and 2, to whose description reference is hereby otherwise expressly made. 
     The single significant difference between application apparatus  210  and application apparatus  10  according to FIG. 1 and 110 according to FIG. 2 is that metering doctor device  234  does not include a doctor rod accommodated in a doctor bed but a doctor blade  270 . In this case, supporting element  226 , abutment element  230  and force appliance  250  perform the function of a blade holder, while force appliance  252  serves to set doctor blade  270  against running base U. Otherwise, the embodiment according to FIG. 3, in particular that which refers to the construction of sealing doctor device  232  with a sealing doctor rod  236  and a doctor bed  240  and to their fixing and driving by force appliances  246  and  248  and the like, corresponds to the embodiments according to FIGS. 1 and 2. 
     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.