Abstract:
In order to provide an easy-to-assemble drier ( 100 ) for drying surface-treated workpieces, in particular vehicle bodies ( 110 ), which are each disposed on a respective workpiece carrier ( 109 ), comprising a drier housing ( 102 ) having a drier tunnel ( 108 ), through which the workpieces are moved along a conveying direction ( 112 ) and which is delimited in a downward direction by a drier floor ( 116 ) comprising a plurality of floor elements ( 118 ), and a conveying device ( 138 ) that conveys the workpieces through the drier tunnel ( 108 ), it is proposed that the conveying device ( 138 ) comprises a plurality of carrying roller units ( 140 ), which are disposed successively in the conveying direction ( 112 ) and each comprise at least one carrying roller ( 142 ), on which the workpiece carriers ( 109 ) rest as they are conveyed through the drier tunnel ( 108 ), wherein the carrying roller units ( 140 ) are each mountable separately on a respective floor element ( 118 ) of the drier floor ( 116 ).

Description:
RELATED APPLICATION 
   This application is a continuation application of PCT/EP2005/012000 filed Nov. 9, 2005, the entire specification of which is incorporated herein by reference. 

   FIELD OF DISCLOSURE 
   The present invention relates to a drier for drying surface-treated workpieces, in particular vehicles bodies, which are each disposed on a respective workpiece carrier, wherein the drier comprises a drier housing having a drier tunnel, through which the workpieces are moved along a conveying device and which is delimited in a downward direction by a drier floor comprising a plurality of floor elements, and a conveying device that conveys the workpieces through the drier tunnel. 
   BACKGROUND 
   Such driers are known from the prior art. 
   In the known driers, the conveying device, that conveys the workpieces through the drier tunnel, is designed for example as a carrying-chain conveyor, in which a vehicle body disposed on a skid frame is placed by means of a rapid-removal belt onto a chain comprising carrying links and/or is carried away by a rapid acceleration of the chain and conveyed on the chain through the drier. For driving and tensioning the chain, there is situated at the start and end of the conveying device a driving and tensioning station comprising driving and tensioning elements disposed outside of the drier housing. 
   During assembly of the known driers, first the drier housing is assembled with the drier tunnel, and then the components of the conveying equipment, such as floor-anchoring devices, conveyor modules, driving and tensioning stations, are introduced into the drier tunnel, welded to the floor panels and fitted together. Finally—in the case of a carrying-chain conveyor—the carrying chain is pulled in. In this case, the accessibility of the drier tunnel from two sides only and the confined spatial conditions in the drier tunnel make it difficult to assemble the conveying device in situ. 
   SUMMARY OF THE INVENTION 
   The underlying object of the present invention is to provide a drier of the initially described type, which is easy to assemble. 
   In a drier having the features of the preamble of claim  1 , this object is achieved according to the invention in that the conveying device comprises a plurality of carrying roller units, which are disposed successively in the conveying direction and each comprise at least one carrying roller, on which the workpiece carriers rest as they are conveyed through the drier tunnel, wherein the carrying roller units are each mountable separately on a respective floor element of the drier floor. 
   The underlying concept of the solution according to the invention is therefore to simultaneously utilize the floor elements, which are used to form the drier floor, additionally for the accommodation of conveying equipment components and hence to integrate the carrying roller units of the conveying device into the drier floor. 
   This offers the advantage that, after mounting of the carrying roller units on the respective floor element, the floor element with the carrying roller unit may be handled as a preassembled unit, which may be brought as a whole to the installation site of the drier and combined there with the remaining component parts of the drier. 
   There is therefore no need for the carrying roller units to be introduced, after completion of the drier, through the entry or exit of the drier tunnel into the drier tunnel and then mounted in the drier. 
   As a result of the use of mechanically and electrically preassembled units for the conveying equipment and the drier floor, assembly at the construction site of the drier is substantially simplified and speeded up. 
   It is moreover particularly easy to match the conveying equipment and the drier housing to one another. Conveying equipment and drier housing may be planned by the same design office and manufactured jointly in the same factory, thereby reducing the number of interfaces needed for planning and manufacture. 
   Owing to the use of the carrying roller units, which may be individually assembled and/or dismantled independently of one another, the conveying equipment according to the invention is of a modular design. Each of these modules is made up of few components such as for example roller block, shafts and gear unit. As these few components may be used for a plurality of different drier designs, they may be stocked in a large piece number. When processing a concrete order, the requisite material may be taken from such stock, thereby markedly reducing the manufacturing time. 
   The conveying device according to the invention having the carrying rollers integrated into the drier floor moreover offers the advantage that it projects up above the floor of the drier tunnel only a little or not at all, so that the height of the drier housing may be reduced by the height of an otherwise necessary conveying device mounted onto the drier floor (up to 50 cm). 
   In the solution according to the invention, the carrying roller units integrated into the drier floor form a roller conveyor, which however is not assembled as a unit outside of the drier and independently of the drier and then introduced into the drier tunnel but, as a result of mounting each of the individual carrying roller units on a respective floor element of the drier floor, may be already integrated into the drier floor before formation of the drier tunnel. 
   The workpiece carriers may in particular take the form of skid frames. 
   By a “skid frame” in the present context is meant a workpiece carrier comprising at least two skid runners, which are oriented along the conveying direction of the workpieces and mutually spaced apart transversely of the conveying direction of the workpieces, wherein each skid runner has a support surface for supporting the skid frame on the conveying device, in particular on a roller conveyor. 
   Here, the skid runners of the skid frame may be fitted directly onto the workpiece so that the workpiece itself effects the connection of the skid runners to one another. 
   In a special development of the invention, it is provided that the carrying roller units each comprise only one carrying roller. 
   Alternatively, it may be provided that the carrying roller units each comprise exactly two carrying rollers, which are disposed substantially coaxially with one another. 
   In a preferred development of the invention, it is provided that the floor elements are load-bearing elements of the drier floor. 
   These floor elements may in particular take the form of profile elements. 
   For the mechanical stability of the drier floor and the conveying device it is particularly advantageous if the floor elements have a U-shaped or a hat-shaped cross section. 
   To the floor elements there may be fastened in particular feet, by which the drier is supported on a foundation of the drier. 
   In order to keep the necessary height of the drier housing as low as possible, it may be provided that the floor elements each have a receiver, in which a carrying roller unit associated with the respective floor element is at least partially accommodated so that the carrying roller unit projects as little as possible up above the drier floor. 
   In a preferred development of the invention, it is provided that the floor elements extend transversely of, preferably substantially at right angles to, the conveying direction. 
   The mechanical stability of the drier floor and the conveying device is further increased when a plurality of floor elements, on each of which at least one carrying roller unit is mounted, are connected to one another by means of at least one stiffening element. 
   These stiffening elements may also take the form of profile elements having a U-shaped or a hat-shaped cross section. 
   For maintenance and repair purposes it is particularly advantageous if the carrying roller units are mounted detachably on the respectively associated floor element. 
   To prevent dirt from the conveying equipment components from passing into the drier tunnel, it is advantageously provided that the floor elements are provided with a cover that has in each case at least one through-opening for a carrying roller of a carrying roller unit. 
   This cover is preferably removable from the respectively associated floor element in order to make the region of the floor element situated under the cover accessible for maintenance and repair purposes. 
   It has further proved advantageous if the carrying roller units each comprise at least one carrying roller shaft, which is mounted on a roller block so as to be detachable for maintenance purposes. 
   In particular, it may be provided that the carrying roller shafts comprise in each case a shaft profile and a sleeve, which is detachably fastened, in particular screw-fastened, to the shaft profile. 
   For ease of exchange of the carrying roller shafts, it is advantageous if the carrying roller shafts after detachment of the at least one sleeve are removable from the respectively associated roller block. 
   In a preferred development of the invention, it is provided that the conveying device comprises a drive device for setting at least one carrying roller of a carrying roller unit in rotation. In this case, the conveying of the workpieces disposed on the workpiece carriers through the drier tunnel may be effected by means of the carrying rollers of the conveying device, and no further drive, in particular no chain drive, is needed for this translational movement. 
   Eliminating the chain conveyor eliminates the material abraded from the chain that otherwise has to be removed at specific intervals from the drier in a cleaning procedure. The need to lubricate the chain is also eliminated, with the added result that no excess lubricating grease may be swirled up by the air flow in the drier and introduced for example into the paint coating of painted workpieces. The maintenance outlay of the conveying device is particularly low as a result of dispensing with a chain. A further result of dispensing with a chain is that no chain breakage can occur. 
   The drive device for setting at least one carrying roller unit in rotation preferably comprises a drive motor, which may for example take the form of a gear motor. 
   In a preferred development of the invention, it is provided that the drive motor is disposed outside of the drier housing. 
   In principle, a separate drive motor may be provided for each driven carrying roller, this allowing each driven carrying roller to be driven at an individual rotational speed and in an individual direction of rotation. 
   As an alternative to this, it may be provided that a plurality of driven carrying rollers are driven by means of the same drive motor. 
   In order that driven carrying rollers situated in conveying direction upstream and downstream of the drive motor may be driven, it is advantageous if the drive motor has a plurality of driven shafts. 
   It is further preferably provided that the drive device comprises at least one connection shaft for transmitting a rotational movement from one element of the drive device to another. 
   At least one of the connection shafts may be oriented transversely of, preferably substantially at right angles to, the conveying direction. Such connection shafts are suitable for transmitting a rotational movement in the longitudinal direction of the floor elements, in particular from a gear unit disposed on the wall of the drier housing to a carrying roller unit. 
   It may further be provided that at least one of the connection shafts is aligned substantially parallel to the conveying direction. Such connection shafts are suitable in particular for transmitting the rotational movement from the drive motor to carrying roller units situated in conveying direction upstream or downstream of the drive motor. 
   Preferably, at least one of the connection shafts, in particular one of the connection shafts oriented substantially parallel to the conveying direction, is disposed outside of the drier housing. 
   In order to transmit the rotational movement from a driven carrying roller to a further carrying roller, it may be provided that at least one of the connection shafts is disposed between two carrying rollers. 
   In order to compensate a misalignment or a not precisely coaxial alignment of two elements of the drive device that are connected to one another by means of a connection shaft, it is advantageous if at least one of the connection shafts is connected by at least one flexible coupling to a carrying roller or to a drive motor or to a gear unit. 
   In a preferred development of the invention, it is provided that the drive device comprises at least one gear unit. 
   Such a gear unit may be disposed in particular on a wall element of the drier housing. 
   To prevent an escape of hot air from the drier interior, it is advantageous if the wall element is connected, preferably welded, in a substantially gastight manner to one of the floor elements of the drier floor. 
   The wall element may further be provided with heat insulation. 
   The gear unit of the drive device may in particular take the form of an angular gear unit in order to be able to deflect the direction of transmission of the rotary drive. 
   In order to prevent hot air from being able to escape from the drier interior in an outward direction along a shaft of the drive device, the drive device preferably has at least one shaft seal for effecting the substantially gastight sealing of a shaft that extends through a wall element of the drier housing. 
   As an alternative to the generation of the translational movement of the workpieces through the drier tunnel by means of a drive device for the carrying roller units, it may also be provided that the conveying device comprises at least one traction means, to which the workpiece carriers may be coupled. 
   In this case, it is possible to dispense with a drive of the carrying rollers in the drier floor; the carrying rollers integrated in the drier floor then merely have the function of carrying and laterally guiding the workpiece carriers with the workpieces disposed thereon, not however of driving the translational movement of the workpiece carriers. 
   The traction means used advantageously comprises at least one driver, which in a coupled position acts upon in each case one workpiece carrier. 
   In order to be able to dispose the traction means return run in the immediate vicinity of the workpiece carrier path, it is advantageous if the driver is movable from the coupled position into an inoperative position, in which it does not act upon the workpiece carriers. 
   The traction means used may in particular take the form of a chain or a rope. 
   Particularly space-saving is a conveying device, in which the traction means forward run and/or the traction means return run—seen from above in plan view—extends between the lateral edges of the workpiece carriers, in particular between the runners of skid frames. 
   When the carrying rollers of the conveying device are disposed in two carrying roller rows extending substantially parallel to the conveying direction, for a space-saving arrangement of the conveying device it is advantageous if the traction means forward run and/or the traction means return run—seen from above in plan view—extends between the two carrying roller rows. 
   It is particularly advantageous if the conveying device of the drier is designed such that the conveying speed of the workpieces along the conveying direction is variable. This means that the distances between the workpieces moving successively along the conveying direction may be varied in any desired manner and for example gaps may be deliberately produced between successive workpieces. 
   A variable conveying speed of the workpieces may easily be generated for example by operating the drive devices of carrying roller units disposed successively in conveying direction at different rotational speeds. 
   The drier may comprise a plurality of sections disposed successively in conveying direction, wherein the conveying speed of the workpieces along the conveying direction varies from section to section. 
   In particular, the drier may be composed of drier modules disposed successively in the conveying direction, wherein the conveying speed of the workpieces varies from module to module. 
   As an alternative to this, it is however also possible to provide in one and the same drier module a plurality of drive devices with different conveying speeds. 
   To prevent the workpiece carriers in the drier from colliding with one another because of the slip between the carrying rollers and the workpiece carriers, it is advantageous if the conveying speed of the workpieces in the drier tunnel increases on average along the conveying direction. 
   In order to be able to introduce the workpieces as rapidly as possible into the drier, in particular within a conveying cycle defined by a conveying device disposed upstream of the drier, it is advantageous if the drier is provided in its entry region with a rapid-removal roller conveyor, which is operated at a much higher conveying speed than the conveying device that conveys the workpieces from the entry region to the exit region of the drier. 
   In a corresponding manner, it is advantageous if the exit region of the drier is provided with a rapid-removal roller conveyor so that the dried workpieces from the drier may be discharged very quickly from the drier, for example within a conveying cycle defined by a conveying device disposed downstream of the drier. 
   A further underlying object of the present invention is to provide a rapid and easy-to-implement method of assembling a drier for drying surface-treated workpieces, in particular vehicle bodies, which are each disposed on a respective workpiece carrier. 
   This object is achieved by a method that comprises the following method steps:
         mounting a plurality of carrying roller units, which are disposed successively in a conveying direction and each comprise at least one carrying roller, on which the workpiece carriers rest as they are conveyed through a drier tunnel of the drier, on a respective floor element of a drier floor of the drier;   subsequently manufacturing the drier using the preassembled units formed by the floor elements and the carrying roller units disposed thereon.       

   Further features and advantages of the invention are the subject matter of the following description and the graphic representation of embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  a diagrammatic cross section through a drier having a drier tunnel, through which vehicle bodies disposed on skid frames are moved by means of driven carrying rollers, which are fastened to hat-shaped profiles of the drier floor; 
       FIG. 2  an enlarged view of the region I of  FIG. 1 ; 
       FIG. 3  an enlarged view of the region II of  FIG. 2 ; 
       FIG. 4  a diagrammatic, part-sectional side view of a section of a drier module with four pairs of carrying rollers; 
       FIG. 5  an enlarged view of the region III of  FIG. 4 ; 
       FIG. 6  a diagrammatic plan view of a conveying device comprising  12  pairs of driven carrying rollers that is integrated into the drier floor of a drier module; 
       FIG. 7  a diagrammatic cross section through a second form of construction of a drier having a drier tunnel, through which vehicle bodies disposed on skid frames are conveyed, and having a conveying device comprising pairs of carrying rollers, of which in each case only one carrying roller is driven; 
       FIG. 8  an enlarged view of the region IV of  FIG. 7 ; 
       FIG. 9  a diagrammatic cross section through a third form of construction of a drier having a drier tunnel, through which vehicle bodies disposed on skid frames are conveyed, and having a conveying device comprising non-driven carrying rollers and a chain, which acts by means of drivers upon the skid frames; 
       FIG. 10  an enlarged view of the region V of  FIG. 9 ; 
       FIG. 11  a diagrammatic cross section through a fourth form of construction of a drier having a drier tunnel, through which vehicle bodies disposed on skid frames are conveyed, and having a conveying device comprising non-driven carrying rollers and a rope, which acts by means of drivers upon the skid frames; 
       FIG. 12  an enlarged view of the region VI of  FIG. 11 ; 
       FIG. 13  a diagrammatic cross section through a fifth form of construction of a drier having a drier tunnel, through which vehicle bodies disposed on skid frames are conveyed, and having a conveying device comprising carrying roller units having in each case two carrying rollers disposed coaxially with one another, which are held on a common carrying roller shaft; 
       FIG. 14  an enlarged view of the region VII of  FIG. 13 ; and 
       FIG. 15  an enlarged view of the region VIII of  FIG. 14 . 
   

   Identical or functionally equivalent elements are denoted by the same reference characters in all of the figures. 
   DETAILED DESCRIPTION OF THE INVENTION 
   A drier represented in  FIGS. 1 to 6  and denoted as a whole by  100  comprises a substantially cuboidal drier housing  102 , which is provided with heat insulation  104 . 
   The interior of the drier housing  102  is subdivided by means of vertical partitions  106  into a drier tunnel  108 , through which vehicle bodies  110  disposed on in each case one skid frame  109  serving as a workpiece carrier are conveyed along a conveying direction  112  extending parallel to the longitudinal direction of the drier  100 , and into two hot-air supply chambers  114  disposed on either side of the drier tunnel  108 . The partitions  106  are provided with hot-air supply nozzles  115 , through which hot air from the hot-air supply chambers  114  passes into the drier tunnel  108  to the vehicle bodies  110 . 
   The drier floor denoted as a whole by  116  comprises, as load-bearing elements, floor elements  118 , which take the form of hat-shaped profiles that extend horizontally and substantially at right angles to the conveying direction  112 . 
   As may best be seen from  FIG. 5 , each of the floor elements  118  comprises an, in cross section, U-shaped middle part having two vertical limbs  120  and a horizontal web  122 , which connects the bottom edges of the vertical limbs  120  to one another, as well as two horizontal flanges  124 , which extend in opposite directions to one another from the top edges of the vertical limbs  120 . 
   These, in cross section, hat-shaped floor elements  118  are disposed successively along the conveying direction  112  at a distance d of for example approximately 1 m. 
   The drier  100  is of a modular construction and comprises a plurality of drier modules  126  disposed successively along the conveying direction  112  and having a predetermined modular length of for example approximately 12 m and hence a predetermined number of for example 12 floor elements, wherein the distance between the start and/or the end of a drier module  126 , on the one hand, and the in each case most closely adjacent floor element  118  is for example approximately 0.5 m (see  FIG. 6 ). 
   The drier module represented in  FIG. 4  has six floor elements  118 . Each of the drier modules  126  is manufactured as a unit in the factory, transported as a unit to the installation site of the drier  100  and joined together there with further drier modules  126  until the desired total length of the drier  100  is achieved. 
   To stiffen the drier floor  116 , the floor elements  118  of a drier module  126  are connected to the respective adjacent floor elements  118  by in each case two stiffening elements  128 , which extend substantially parallel to the conveying direction  112  in each case between the left ends and between the right ends of the floor elements  118 . 
   These stiffening elements  128  may likewise take the form of hat-shaped profiles. 
   The floor elements  118  and the stiffening elements  128  therefore together form a load-bearing floor frame  130  of the drier floor  116 . 
   Welded onto the underside of the webs  122  of the floor elements  118  there is in each case a plurality of feet  132 , by which the floor frame  130  is supported on a foundation  134  (see  FIG. 4 ). 
   As may be seen for example from  FIG. 1 , there is further fitted to the underside of the floor elements  118  and the stiffening elements  128  heat insulation  136 , which extends also through the gaps that are left in the drier floor  116  between the floor elements  118  and the stiffening elements  128 . 
   For conveying the vehicle bodies  110  disposed on the skid frames  109  through the drier tunnel  108 , each drier module  126  further comprises a conveying device  138 , which in turn comprises a plurality of carrying roller units  140  that are disposed successively along the conveying direction  112  and integrated into the floor frame  130 . 
   Each of the carrying roller units  140  comprises in each case one substantially cylindrical carrying roller  142 , which is disposed in a rotationally fixed manner on a carrying roller shaft  144 , and one roller block  146 , on the two limbs  148  of which the carrying roller shaft  144  is mounted by means of ball bearings  150  rotatably about a horizontal axis of rotation  152  extending at right angles to the conveying direction  112 . 
   The two limbs  148  of each roller block  146  extend upwards from a common horizontal base plate  153 . 
   In each case two of these carrying roller units  140  are fastened in a mutually independently detachable manner to each of the floor elements  118 , namely in such a way that the carrying rollers  142  of the two carrying roller units  140  are aligned coaxially with one another and mutually spaced apart at right angles to the conveying direction  112 . 
   As may be seen from  FIG. 6 , the carrying rollers  142   a  fastened in each case (viewed in conveying direction  112 ) on the left to the floor elements  118  are disposed in a mutually aligned manner along the conveying direction  112 , so that these lefthand carrying rollers  142   a  form a lefthand carrying roller row  154   a.    
   In a corresponding manner, the carrying rollers  142   b  disposed in each case (viewed in conveying direction  112 ) on the right on the floor elements  118  are likewise disposed in a mutually aligned manner in conveying direction  112 , so that these righthand carrying rollers  142   b  together form a righthand carrying roller row  154   b.    
   The carrying roller units  140  are fastened preferably detachably to the floor elements  118 , for example by screw-fastening their roller blocks  146  to the webs  122  of the floor elements  118 . 
   The screw-fastening of the roller blocks  146  to the floor elements  118  is effected in a way that allows a dismantling and an aligning of the carrying rollers  142  with little effort. 
   As may best be seen from  FIG. 2 , the inner space  156  of each floor element  118  that is delimited by the vertical limbs  120  and the web  122  of the relevant floor element  118  forms in each case a receiver for the two carrying roller units  140  disposed on the floor element  118 , in which receiver the roller blocks  146  of these carrying roller units  140  are completely accommodated. 
   This inner space  156  of each floor element  118  is covered in an upward direction, i.e. in the direction of the drier tunnel  108  and/or the hot-air supply chambers  114 , in each case by a cover plate  158 . 
   These cover plates  158  are detachably fastened, in particular screw-fastened, in each case to the horizontal flanges  124  of the respective floor element  118 . 
   Preferably, each of these cover plates  158  extends over substantially the entire length of the respective floor element  118  in order, by removing the cover plate  158 , to make the entire inner space  156  of the floor element  118  accessible for maintenance or cleaning purposes. 
   Each of the cover plates  158  has in the region of the carrying roller units  140  in each case one substantially rectangular through-opening  160  for in each case one carrying roller  142 , through which through-opening the respective associated carrying roller  142  extends so that the crest of the carrying roller  142 , on which the skid frames  109  to be conveyed rest by in each case one of their runners  162 , is disposed above the cover plate  158 . 
   So that the skid frames  109  with the vehicle bodies  110  disposed thereon may be moved through the drier tunnel  108 , in the form of construction of the drier  100  represented in  FIGS. 1 to 6  all of the carrying rollers  142  of a drier module  126  may be set in rotation about their axes of rotation  152  by means of a drive device denoted as a whole by  164 . 
   As may best be seen from  FIGS. 4 to 6 , the drive device  164  of the drier module  126  comprises a drive motor  166 , which is disposed on the outside of the drier housing  102 , i.e. outside of the heat insulation  104 , roughly centrally on a longitudinal side of the drier module  126 . 
   The drive motor  166  takes the form of a gear motor and has two driven shafts  168  oriented in mutually opposite directions parallel to the conveying direction  112 . 
   With each floor element  118  there is associated in each case a gear unit  170 , which is screwed onto a vertical end plate  172 , which is welded at one of the ends (for example at the, viewed in conveying direction  112 , right end) of the floor element  118  in a gastight manner into the floor element  118  so that it seals off the inner space  156  of the floor element  118  in a gastight manner from the outside of the drier  100  and hence prevents hot air from escaping out of the drier  100 . 
   On the inside of the end plate  172  facing the inside of the drier  100 , heat insulation is disposed. 
   The gear units  170  take the form of angular gears, in particular bevel gears, and comprise in each case a drive-end input shaft  174 , a first output shaft  176  aligned parallel to the input shaft  174 , and a second output shaft  178  extending in horizontal direction and at right angles to the input shaft  174  into the interior of the drier  100 . 
   The input shaft  174  of each gear unit  170  is connected by in each case one longitudinal connection shaft  180 , which extends substantially horizontally and parallel to the conveying direction  112 , either to one of the driven shafts  168  of the drive motor  166  or to the first output shaft  176  of another gear unit  170  positioned closer to the drive motor  166 . 
   The longitudinal connection shafts  180  are in this case connected at their one end by means of in each case one coupling  182  in a rotationally fixed manner to one of the driven shafts  168  of the drive motor  166  or to an output shaft  176  of a gear unit  170  and at their other end likewise by means of a coupling  182  to the input shaft  174  of a gear unit  170 . 
   The couplings  182  may be of a flexible, in particular pliable design in order to allow compensation of any misalignment and/or deviation in the alignment of the shafts that are to be connected to one another by the longitudinal connection shaft  180 . 
   The longitudinal connection shafts  180  may in particular comprise pipes, to the ends of which shaft profiles are fastened, in particular welded. 
   The first output shaft  176  of each gear unit  170  is connected by in each case one longitudinal connection shaft  180  to the input shaft  174  of a gear unit  170  situated further away from the drive motor  166 . Only the gear units  170 , which are disposed right at the start and/or right at the end of a drier module  126  and are not succeeded by a further gear unit  170 , are not connected at their first output shafts  176  to a further longitudinal connection shaft  180 . 
   The second output shaft  178  of each gear unit  170  that extends at right angles to the conveying direction  112  into the inner space  156  of in each case one floor element  118  is sealed off in a substantially gastight manner from the exterior of the drier  100  by means of a shaft seal (not shown) situated inside the housing of the gear unit  170 , thereby preventing hot air from the interior of the drier  100  from escaping outwards along this output shaft  178 . 
   Each of these second output shafts  178  is connected by in each case one transverse connection shaft  184 , which extends substantially at right angles to the conveying direction  112  through the inner space  156  of a floor element  118 , to the carrying roller shaft  144  of the in each case closer-lying carrying roller  142   b.    
   The transverse connection shafts  184  likewise comprise in each case a pipe  186 , to each end of which a shaft profile  188  is fastened, in particular welded (see in particular  FIG. 3 ). 
   Each transverse connection shaft  184  is connected at its one end by a coupling  190  to the second output shaft  178  of a gear unit  170  and at the opposite end by a coupling  192  to the carrying roller shaft  144  of the carrying roller  142   b.    
   The two couplings  190  and  192  may be of a flexible, in particular pliable design to allow them, in the event of the transverse connection shaft  184  not being aligned exactly with the second output shaft  178  of the gear unit  170  and/or with the carrying roller shaft  144  of the carrying roller  142   b , to adapt to the position and alignment of these shafts. 
   As may be seen from  FIG. 3 , the coupling  192  may in particular comprise a hollow-cylindrical sleeve  194 , which receives the carrying-roller-side shaft profile  188  of the transverse connection shaft  184  and a connection-shaft-side shaft profile  196  formed on the end of the carrying roller shaft  144 . 
   So that the carrying roller  142   a  situated further away from the gear unit  170  and disposed on the same floor element  118  may be set in rotation, the carrying roller shaft  144   b  of the carrying roller  142   b  disposed closer to the gear unit  170  is connected by a further transverse connection shaft  198  to the carrying roller shaft  144   a  of the carrying roller  142   a  situated further away from the gear unit  170 . 
   The transverse connection shaft  198  extends substantially at right angles to the conveying direction  112  through the inner space  156  of the floor element  118  and is connected in a rotationally fixed manner by couplings  192  at its two ends to the carrying roller shafts  144   a  and  144   b.    
   In order to be able to compensate a misalignment and/or a deviation in the alignment of the carrying roller shafts  144   a ,  144   b , the couplings  192  are preferably of a flexible, in particular pliable, design. 
   The couplings  192  may in particular, like the coupling  192  between the transverse connection shaft  184  and the carrying roller shafts  144   b , comprise a hollow-cylindrical sleeve  194  that accommodates the shaft profiles of the shafts that are to be connected to one another. 
   The couplings  192  are detachably fastened, in particular screw-fastened to the shaft profiles  196  of the carrying roller shafts  144 , thereby allowing their removal from the carrying roller shafts  144 . After detachment of the couplings  192  from the carrying roller shafts  144 , the carrying roller shafts  144  may be displaced along their axis of rotation  152  relative to the respective associated roller block  146  and then removed upwards in the direction of the drier tunnel  108  from the roller block  146  after the cover plate  158  has previously been removed from the floor element  118  to make the inner space  156  of the floor element  118  accessible from the drier tunnel  108 . 
   In this way, it is possible to dismantle the carrying roller shafts  144  in order to be able to exchange, for example, a roller block  146 , a ball bearing  150  of a roller block  146 , or a carrying roller  142 . 
   In a variant of the previously described form of construction, it may alternatively be provided that the two carrying rollers  142   a ,  142   b  disposed on the same floor element  118  are not connected by a transverse connection shaft  198  disposed between them but are instead disposed on a common carrying roller shaft  144 , which extends through the inner space  156  of the floor element  118  from the one carrying roller  142   a  to the other carrying roller  142   b.    
   With the previously described drive device  164 , it is possible by means of the frequency-controlled drive motor  166  to allow all of the carrying rollers  142  to rotate at the same rotational speed about their axes of rotation  152 , so that the skid frames  109  resting on the carrying rollers  142  and the vehicle bodies  110  disposed on the skid frames  109  are moved along the conveying direction  112  because of the friction between the runners  162  of the skid frames  109  and the peripheral surfaces of the carrying rollers  142 . 
   For lateral guidance of the skid frames  109  during this movement, the carrying rollers  142   b  disposed in each case on the right and/or the carrying rollers  142   a  disposed in each case on the left may be provided with one or more wheel flanges  200  (see  FIG. 3 ). 
   Should there be slip between the skid frames  109  and the carrying rollers  142 , this slip may then be compensated by means of different rotational speeds of the drive motor  166 . 
   To prevent skid frames  109  from colliding with one another owing to different slip, it may be provided that the rotational speed of the drive motors  166  of drier modules  126  disposed successively in conveying direction  112  gradually increases in conveying direction  112 , with the result that the conveying speed of the skid frames  109  gradually increases in conveying direction  112 , so that the vehicle bodies  110 , as they travel through the drier tunnel  108 , are pulled apart from one another and therefore prevented from bumping into one another. 
   Instead of a single drive device  164 , one or more or all of the drier modules  126  of the drier  100  may be provided with a plurality of drive devices  164  each comprising a drive motor  166 , so that the conveying speed of the skid frames  109  may be varied also within the same drier module  126  by operating the drive motors  166  of the drive devices  164 , disposed successively in conveying direction  112 , of the relevant drier module  126  at different rotational speeds. 
   Conversely, it is also conceivable for a plurality of drier modules  126  disposed successively in conveying direction  112  to have a common drive device  164  comprising only one drive motor  166 , so that this drive motor  166  then drives the carrying rollers  142  of a plurality of drier modules  126 . 
   The carrying roller units  140  disposed in the entry region and/or in the exit region of the drier  100  may form in each case a rapid-removal roller conveyor, which is operated at a particularly high conveying speed of for example approximately 30 m/min in order to convey the vehicle bodies  110  very quickly, in particular within a defined cycle time, into the drier  100  and/or out of the drier  100  and transfer them to a downstream conveying device. 
   In particular, it is therefore possible, in the case of a drier  100  disposed at a different height level to a conveying device disposed upstream of the drier  100 , within a conveying cycle to raise or lower in each case one vehicle body  110  to the level of the drier  100  by means of a lifting device, move the vehicle body  110  into the drier tunnel  108  by means of the rapid-removal roller conveyor and then lower or raise the empty lifting device in order to receive the next vehicle body  110 . 
   In a corresponding manner, in the case of a drier  100  disposed at a different height level to a conveying device disposed downstream of the drier, it is possible within a conveying cycle of the downstream conveying device by means of the rapid-removal roller conveyor in the end region of the drier  100  to move in each case one vehicle body  110  out of the drier tunnel  108  onto the lifting device, lower or raise the vehicle body  110  by means of the lifting device, transfer the vehicle body  110  at the different height level to the downstream conveying device and then raise or lower the empty lifting device in order to receive the next vehicle body  110 . 
   Between the rapid-removal roller conveyors in the entry region and in the exit region of the drier  100  the vehicle bodies  110  are conveyed at the normal conveying speed of for example approximately 3 m/min. 
   The rapid-removal roller conveyors in the entry region and in the exit region of the drier  100  are of an identical construction to the previously described conveying device  138 . 
   A drier module  126  for the entry region or for the exit region of the drier  100  may in particular be equipped with two drive devices  164  each comprising a drive motor  166 , wherein the one drive device  164  drives the carrying rollers  142  of the respective rapid-removal roller conveyor at the rotational speed for a higher driving speed, while the other drive device  164  drives the carrying rollers  142  adjoining the rapid-removal roller conveyor at the rotational speed for the normal conveying speed. 
   The conveying speed in the drier  100  may easily be varied by disposing a plurality of mutually independently operating drive devices  164  successively in conveying direction  112  in the drier  100 . It is also possible for the vehicle bodies  110  to be brought to a complete halt or moved temporarily counter to conveying direction  112 . 
   When the drier  100  comprises for example a recirculating-air drier section and a UV-radiation drier section, which are disposed successively in conveying direction  112 , then the vehicle bodies  110  may be conveyed for example through the recirculating-air drier section at the normal conveying speed of for example approximately 3 m/min, then brought to a halt for a required dwell time in the UV-radiation drier section for irradiation with UV light, and then conveyed further at an increased conveying speed in order to reach on average the normal conveying speed once more. 
   It is also possible by suitable control of the drive devices  164  to produce between two vehicle bodies  110  succeeding one another in conveying direction  112  a gap that allows a UV irradiation device to be introduced between the two vehicle bodies  110  so that the rear of the front vehicle body  110  and the front of the rear vehicle body  110  may be irradiated. 
   For manufacture of the previously described drier  100 , first the floor frame  130  of the drier floor  116  of a drier module  126  is manufactured. Then, the carrying roller units  140  are fastened individually to the floor elements  118  of the floor frame  130 , and the drive device  164 , which comprises in each case a drive module  166  as well as gear units  170 , longitudinal connection shafts  180  and transverse connection shafts  184 ,  198 , is mounted on the floor frame  130 . 
   After completion of this assembly step, the floor frame  130  and the conveying device  138  comprising the carrying roller units  140  and the drive device  164  form a mechanically and electrically preassembled unit that may be handled as a whole. 
   This preassembled unit may be brought as a whole to the site where the drier  100  is to be installed and, there, may be combined with the remaining component parts of the drier  100 . 
   As an alternative to this, it is also possible to manufacture the complete drier module  126  including the preassembled unit of floor frame  130  and conveying device  138  at the factory and then transport the complete drier module  126  to the installation site of the drier  100  and combine it there with further drier modules  126  to form the finished drier  100 . 
   A second form of construction of a drier  100  that is represented in  FIGS. 7 and 8  differs from the previously described first form of construction in that, of each pair of carrying rollers  142  associated with a floor element  118 , in each case only one carrying roller  142 , namely the carrying roller  142   b  disposed closer to the gear unit  170 , is set in rotation about its axis of rotation  152  by means of the drive device  164 . 
   The carrying roller  142   a  situated further away from the gear unit  170 , on the other hand, is not driven but simultaneously rotates merely because of the friction between the runners  162  of the skid frames  109  and the peripheral surface of the carrying roller  142   a  when the skid frame  109  is moved in conveying direction  112  by means of the driven carrying roller  142   b.    
   In this form of construction, the non-driven carrying rollers  142   a  are therefore used merely to support the skid frames  109  having the vehicle bodies  110  disposed thereon, not however to drive the skid frames  109 . 
   The transverse connection shaft  190  provided between the two carrying rollers  142   a  and  142   b  in the first form of construction therefore no longer applies. 
   Otherwise, the second form of construction represented in  FIGS. 7 and 8  corresponds in construction, function and assembly method to the first form of construction represented in  FIGS. 1 to 6 , to the above description of which reference is made in this respect. 
   A third form of construction of a drier  100  that is represented in  FIGS. 9 and 10  differs from the previously described forms of construction in that neither the lefthand carrying rollers  142   a  nor the righthand carrying rollers  142   b  are set in rotation, all of the carrying rollers  142  instead merely having the task of supporting the skid frames  109  with the vehicle bodies  110  disposed thereon and guiding them laterally in the course of a movement along the conveying direction  112 . 
   Consequently, this form of construction dispenses entirely with the drive device  164  for setting the carrying rollers  142  in rotation. 
   Rather, the skid frames  109  with the vehicle bodies  110  disposed thereon are set in translational motion in conveying direction  112  by means of a traction means in the form of a chain  202 , which revolves along the conveying direction  112  and has drivers  204 , which are mutually spaced apart along the chain  202  and are pivotable between a coupled position, in which the driver  204  may act upon a cross-member  206  of in each case one skid frame  109  in order to pull the relevant skid frame  109  in the direction of motion of the chain, and an inoperative position, in which the driver  204  is laid flat in such a way that it runs through underneath the cross-members  206  of the skid frames  109  without touching them. 
   The chain  202  travels through a chain forward run  208 , which extends approximately centrally between the carrying roller rows  154   a  and  154   b  along the conveying direction  112  and in which the chain, which is guided at guide rails (not shown), moves in conveying direction  112  and the drivers  204  of the chain  202  are in the coupled position, a tensioning and driving station (not shown) disposed in the exit region of the drier  100 , a chain return run  210 , which is disposed between the chain forward run  208  and the carrying roller row  154   b  and in which the chain moves counter to the conveying direction  112  and the drivers  204  of the chain  202  are in the inoperative position, and a deflection station (not shown), which is disposed in the entry region of the drier  100  and which in turn is adjoined by the chain forward run  208 , so that the chain  202  closed in the form of a ring revolves continuously through the drier  100 . 
   Otherwise, the third form of construction of a drier  100  represented in  FIGS. 9 and 10  corresponds in construction, function and assembly method to the first form of construction represented in  FIGS. 1 to 6 , to the above description of which reference is made in this respect. 
   A fourth form of construction of a drier  100  that is represented in  FIGS. 11 and 12  differs from the third form of construction represented in  FIGS. 9 and 10  in that, instead of a chain  202 , as a traction means for setting the skid frames  109  with the vehicle bodies  110  disposed thereon in translational motion a rope  212  is used, in particular a steel rope, that has drivers  204  disposed at mutual intervals along the rope  212 . 
   In this case too, the drivers  204  are pivotable from a coupled position, in which they hook into the cross-member  206  of a skid frame  109  and may therefore pull the skid frame  109  in conveying direction  112 , and an inoperative position, in which the drivers  204  are laid flat in such a way that they run through underneath the cross-members  206  of the skid frames  109  without touching them. 
   In this form of construction, the rope  212  travels through a rope forward run  214 , which extends between the carrying roller units  154   a ,  154   b  close to the lefthand carrying roller row  154   a  along the conveying direction  112  and in the region of which the drivers  204  are in the coupled position, a tensioning and driving station (not shown) disposed in an exit region of the drier  100 , a rope return run  216 , which extends between the carrying roller rows  154   a ,  154   b  close to the righthand carrying roller row  154   b  along the conveying direction  112  and in the region of which the drivers  204  are in the inoperative position, and a deflection station, which is disposed in an entry region of the drier  100  and adjoined by the rope forward run  214 , so that the rope  212  closed in the form of a ring revolves continuously through the drier  100 . 
   In this case, the drivers  204  situated in the rope forward run  214  and acting upon in each case one cross-member  206  of a skid frame  109  pull the skid frames  109  in conveying direction  112 . 
   Otherwise, the fourth form of construction of a drier  100  represented in  FIGS. 11 and 12  corresponds in construction, function and assembly method to the third form of construction represented in  FIGS. 9 and 10 , to the above description of which reference is made in this respect. 
   A fifth form of construction of a drier  100  that is represented in  FIGS. 13 to 15  differs from the form of construction represented in  FIGS. 1 to 6  in that each of the carrying roller units  140  disposed successively in conveying direction  112  comprises not just a single carrying roller  142   a  and/or  142   b  but both the (viewed in conveying direction  112 ) lefthand carrying roller  142   a  and the righthand carrying roller  142   b  of a carrying roller pair. 
   In this form of construction, both carrying rollers  142   a ,  142   b  are disposed in a rotationally fixed manner on a common carrying roller shaft  144 , which is mounted on the two limbs  148  of a roller block  146  of the carrying roller unit  140  by means of ball bearings  150  rotatably about a horizontal axis of rotation  152  that extends at right angles to the conveying direction  112 . 
   As  FIGS. 13 to 15  reveal, in this case the (viewed in conveying direction  112 ) lefthand limb  148   a  of the roller block  146  is disposed on the left of the lefthand carrying roller  142   a  and the righthand limb  148   b  of the roller block  146  is disposed on the right of the righthand carrying roller  142   b.    
   Both limbs  148   a ,  148   b  of the roller block  146  extend upwards from a common horizontal base plate  153 , which extends in the longitudinal direction of the floor element  118  across the entire gap between the carrying rollers  142   a ,  142   b.    
   This base plate is screw-fastened to the web  122  of the relevant floor element  118 . 
   In this form of construction, therefore, in each case only one carrying roller unit  140  is fastened detachably to each of the floor elements  118 . 
   The common carrying roller shaft  144  is connected by a, preferably flexible, coupling  192  in a rotationally fixed manner to the transverse connection shaft  184 , via which the common carrying roller shaft  144  and hence both carrying rollers  142   a ,  142   b  are set in rotation by means of the drive device  164 , as in the previously described first form of construction. 
   Since in the fifth form of construction represented in  FIGS. 13 to 15  both carrying rollers that are associated with the same floor element  118  are seated on the same carrying roller shaft  144 , this form of construction dispenses with the transverse connection shaft  198  of the first form of construction as well as the couplings  192  thereof. 
   Otherwise, the fifth form of construction of a drier  100  represented in  FIGS. 13 to 15  corresponds in construction, function and assembly method to the first form of construction represented in  FIGS. 1 to 6 , to the above description of which reference is made in this respect.