Abstract:
The invention relates to a method of introducing and removing workpieces, particularly vehicle bodies, into and out of a treatment area ( 20, 70 ) suitable for the surface treatment of the workpieces ( 1 ), wherein the workpieces ( 1 ) are detachably secured to mounting frames ( 7 ) that each have a rotary axis ( 13, 41, 61 ) aligned transverse to the direction of movement of the workpieces ( 1 ), the rotary axes ( 13, 41, 61 ) are continuously moved translationally and at a constant speed, and the workpieces ( 1 ) at the start and end of the treatment area ( 20, 70 ) are simultaneously rotated through about 180° around one of these rotary axes ( 13, 41, 61 ) in a controlled and always guided manner in the direction of the translational movement. The invention also relates to a device for the surface treatment of workpieces and a system for the surface treatment of vehicle bodies.

Description:
This is a continuation of copending application Ser. No. PCT/EP97/05394 filed Oct. 1, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The invention relates to a method of introducing and removing workpieces, particularly vehicle bodies, into or out of a tank or a treatment booth, whereby the workpieces inside the tank are treated either in a gaseous environment such as being coated with powder or wet paint, or the tank is a dip tank filled with a liquid medium suitable for the surface treatment of the workpieces. The invention also relates to an apparatus for the surface treatment of workpieces and to a system for the surface treatment of vehicle bodies. 
     In the subject matter according to the invention, the workpieces or vehicle bodies are continuously moved in a translational manner toward a treatment area such as a treatment bath, a treatment booth etc. and are transported to and from the treatment area while maintaining this movement. 
     2. Prior Art 
     Devices for the surface treatment of one or more vehicle bodies are generally divided into continuous and non-continuous conveyors. 
     In the case of non-continuous conveyors, so-called cyclical systems, the vehicle bodies on object supports are sequentially transported over successively arranged dip tanks where they are stopped. Lifting or rotating devices are used to dip the vehicle bodies into a bath medium suitable for surface treatment and located in the dip tank, and the vehicle bodies are lifted out again once the process time is over. These systems manage without inlet and discharge areas, allowing the treatment bath dip tanks to be shorter than in the case of continuous conveyors. These systems can only be used, however, at small production rates because system capacity depends on the desired process time and is therefore considerably restricted. The application range of such systems is consequently limited. 
     A rotating device for cyclically operating systems is known from DE 43 04 145 C1 which discloses a rotating device securely mounted above a dip tank and to which at least one vehicle body can be secured. Rotation through approximately 180° of the rotating device causes a vehicle body to be dipped into a treatment bath and a further rotation causes it to be guided out. 
     In the case of continuously conveying systems, vehicle bodies are continuously transported along the aligned treatment baths and are guided into and out of the treatment bath using lowering and raising means into and out of the bath medium. Due to the continuous conveyance of these systems, a treatment bath&#39;s inlet and outlet areas have to be designed at an angle. Each dip tank therefore requires a longer inlet and discharge area, which causes a dip tank and hence the entire system to be considerably extended. The known lowering means likewise do not ensure that air pockets remain in the workpieces dipped in the treatment bath. Due to cavities entailed by the structural design, this problem arises to an extreme degree particularly when vehicle bodies are dipped into the treatment bath. In the prior art, additional steps are therefore absolutely essential in order to reduce air pockets. It is for example proposed in GB 1 434 348 to move to and fro a lowered vehicle body that is dipped into the treatment bath. 
     A continuous conveyor for guiding workpieces in galvanic metallization and chromium-plating plants is known from German published document DE-AS 25 12 762. The system known from this document relates to a revolving conveyor device that continuously transports the workpiece to be treated. When the conveyor device rotates, the workpieces are each automatically dipped into a tank, guided underneath it while continuing the movement, moved out of the tank and again dipped into the next tank. Various options are mentioned in order to cause the workpieces to be dipped in or lifted out. 
     On the one hand, workpiece holders are rotatable by cams or by ramps and surfaces that extend downwards at an angle. When such a workpiece holder continues to move, however, only the rotation is initiated, the further rotational process takes place in an uncontrolled manner merely under the influence of gravity. Such a device suffers from the drawback that heavier workpieces fall into a treatment bath in an uncontrolled manner, which is totally unsuitable for larger, much heavier and more sensitive workpieces such as vehicle bodies. The system described therein also specifically focuses upon a design having current carrying means which simultaneously serve as an actuator for initiating a workpiece holder&#39;s rotation. The rotational process which is uncontrolled and hence indefinite in terms of time and place also makes it impossible to minimize the individual dip tanks&#39; inlet and outlet areas. The system disclosed therein does not aim thereat either. 
     Finally, a container rotation device is known from German published document DE-OS 29 01 027; in this device, containers., preferably bottle containers, are intended to be rotated automatically and without manual action. The device comprises conveyance means, drivers that are rotatably supported in a mount, and a curved control surface which controls the drivers such that they secure the containers. chain wheels connected to the drivers engage with gear teeth. 
     The arrangement is such that the chain wheels, drivers and containers are rotated as a result of engagement with the teeth. Only the rotation by means of chain wheels is disclosed in the device shown therein. The container is also intended to be rotated only in order that various container parts are more effectively accessible. An insertion or removal process as a result of rotation is neither depicted nor in any way implied. 
     SUMMARY OF THE INVENTION 
     Technical Problem 
     The technical problem upon which the invention is based is to provide a method and an apparatus for the surface treatment of workpieces, in which on the one hand the treatment areas can be minimized in terms of their dimensions, while on the other hand, high production rates can also be achieved. 
     Solution of the Technical Problem 
     This technical problem is solved by a method of introducing and removing workpieces, particularly vehicle bodies, into and out of a treatment area suitable for the surface treatment of said workpieces, wherein said work pieces are detachably secured on mounting frames which each have a rotary axis vertically aligned in relation to the direction of movement of said workpieces, said rotary axes are continuously moved translationally and at a constant speed, and said workpieces at the start and at the end of said treatment area are simultaneously rotated through about 180° around one of these rotary axes in a controlled and always guided manner in the direction of the translational movement. 
     An apparatus solving the above technical problem for the surface treatment of workpieces in treatment for baths or treatment booths, particularly for the surface treatment of vehicle bodies, comprises at least one mounting frame for receiving one or more workpieces, said frame being continuously moveable along a direction of movement of said workpieces predetermined by the arrangement of said treatment bath or said booth, having receiving means with which said workpiece can be detachably fitted to said mounting frame, and having a rotary axis disposed across the direction of movement, actuating means for rotationally shifting said mounting frame around its rotary axis, said actuating means and said mounting frame being constantly coupled together during the process of rotation so that the rotation is always controlled and guided, guidance means with which said mounting frame can be guided in the direction of movement, and drive means with which said mounting frame is continuously moveable in the direction of movement. 
     The technical problem is also solved by a system for the surface treatment of vehicle bodies comprising a plurality of successively arranged treatment baths, a supply means for supplying said vehicle bodies individually in an inlet area, a device for the surface treatment of workpieces in said treatment baths, particularly for the surface treatment of vehicle bodies, with at least one mounting frame for receiving one or more workpieces, said frame being continuously moveable along a direction of movement of said workpieces predetermined by the arrangement of said treatment bath or said booth, having receiving means with which said workpieces can be detachably fitted to said mounting frame, and having a rotary axis disposed across the direction of movement, actuating means for rotationally shifting said mounting frame around its rotary axis, said actuating means and said mounting frame being constantly coupled together during the process of rotation so that the rotation is always controlled and guided, guidance means with which said mounting frame can be guide in the direction of movement, and drive means with which said mounting frame is continuously moveable in the direction of movement, wherein said plurality of spaced apart mounting frames is continuously moved above said plurality of successively arranged treatment baths, wherein the vehicle bodies are individually supplied in said inlet area by said supply means in accordance with the movement speed of said mounting frames, and wherein in an outlet area of said system, the now treated vehicle bodies are detached and can be removed, from said mounting frames by detachment means while continuously moving said frames. 
     Such a system is also usable in connection with treatment booths instead of treatment baths. 
     The invention is based on the idea of rotating the workpieces to be introduced into the treatment areas, during a continuous movement of these workpieces, at the boundary area of a treatment area at the same time as a controlled and completely guided rotational movement around a rotary axis across the workpieces&#39; continuous direction of movement. As a result of this first ever co-ordination of the workpieces&#39; continuous movement along the treatment areas and the simultaneous completely guided rotational movement thereof around the rotary axis located across the direction of conveyance, the workpieces, particularly vehicle bodies, can be rotated into and out of a treatment area with such accuracy that the inlet and outlet areas of each treatment area can be provided with vertical or almost vertical end walls. The length of each individual treatment area can therefore be reduced to a minimum. At the same time, this minimizes the total length of a system that has a plurality of successively arranged treatment areas and particularly a number of treatment baths arranged in a row. This reduction is about 20% for a capacity of one hundred vehicle bodies per hour compared to conventional continuous conveying systems. The advantages of a continuous conveying system are therefore combined for the first time with a rotational device&#39;s benefits as known from the prior art. 
     In the case of a treatment bath composed of a liquid medium, air bubbles are largely avoided by the rotational process while the workpieces are being dipped. Even if the workpiece is dipped, the air pockets that may have been caused by the treatment process can also be reduced, however, by moving further the workpiece in the treatment bath. In addition, occlusions of dirt on horizontal surfaces are reduced because the vehicle bodies are rotated above and within the bath. 
     In the method according to the invention, all that has to be provided is a minimum safety gap between the workpiece to be introduced into the treatment area and the end walls of the treatment area or dip tank. To ensure a minimum total length of the treatment area, the rotational speed and speed of movement then have to be coordinated with one another, by taking the safety gap into consideration, such that after completion of the rotational process, while observing the safety gap, the front section of the workpiece is positioned at the first end wall and is positioned at the second end wall during the process of removal by rotation. In the prior art, this minimum safety gap has to be much larger, as for example in the chromium-plating system known in the prior art and in which a completely uncontrolled process of insertion by rotation occurs. By coordinating the speed of the translational movement and the speed of rotating the workpiece in and out, the workpiece&#39;s movement curve can be accurately predetermined and adapted to the shape of the treatment area to an optimum degree. The total length can therefore be kept to a minimum as well. 
     By keeping the rotational speed essentially constant, a steady movement curve can be achieved, which is particularly important in the case of heavier workpieces so as to achieve an even process of rotation in and out, because greater forces which do not permit an accurate movement sequence otherwise take effect when there are changes in angular velocity. For example when the heavy vehicle bodies placed on a mounting frame temporarily move further than desired during rotation in and out due to inertia when there is a change in angular velocity. 
     The procedure according to the invention can be used for a wide variety of surface treatment techniques. For instance, the introduction and removal of workpieces into and out of a liquid medium is perfectly suited to performing dip coating. The procedure according to the invention is also, however, very well suited to powder coating or wet paint application. As with the treatment tanks needed for dip coating, the treatment booths envisaged for this purpose raise the problem of guiding the workpieces in and out of an inlet and outlet area of the booths. In consequence, these booths may be located above or below the workpieces&#39; supply level. 
     Finally, the linking, according to the invention, of a continuous translational movement and a controlled and constantly guided rotary movement of the workpieces is also suitable for preventing the formation of fat edges in a dryer when workpieces have already been coated. For this purpose, instead of a gap between the rotary axis and the workpiece, the workpiece should be optimally arranged close to the rotary axis or even within the area of the rotary axis in the surface treatment apparatus according to the invention. 
     A mechanically very simply structured and low-maintenance design is obtained by providing the mounting frame with at least one laterally attached lever which interacts with a guide in order to cause the mounting frame to rotate. By adapting the lever length, heavy workpieces can also by rotated on a mounting frame in a very easily controlled manner. 
     Attaching at least one lever on opposite sides of a mounting frame—whereby these opposite levers are counterrotated by a predetermined angular amount—for the first time ensures that if the guidance devices are correspondingly designed, the mounting frame is always supported both in the forward direction and in the reverse direction in relation to the rotational direction and is therefore also accurately guided. 
     This effect can also be improved when two levers are disposed on each side of the mounting frame; these levers are each disposed on one side of the mounting frame symmetrical to the rotary axis and lever configurations on the opposite sides are rotated through 90°. 
     A very simple embodiment of the actuation means is obtained by designing it as a directional rail. 
     By providing guide surfaces on the directional rails in the inlet and outlet area of a treatment bath, i.e. in the boundary area, the rotation can be brought about by simply sliding corresponding devices up and down on the mounting frame or by rolling them off the frame. 
     Rotation is best controlled by upwardly or downwardly tilted guide portions which are inexpensive and easy to manufacture as a result of designing the individual guide portions to be simple and straight. 
     The individual guide portions are best tilted downwards through about 45°, other guide portions are tilted upwards through about 45°. 
     A low-friction and easy-maintenance design is obtained in that rollers which interact with the directional rails are disposed at the lever ends. 
     More complex, albeit extremely accurate actuation devices which can even be used with the heaviest of items comprise toothed racks or screw spindles securely attached to the treatment bath and which interact with gear wheels or worm gears correspondingly formed on the mounting frame. 
     This also makes it possible to insert intermediate gears if need be. 
     In the area of the rotary axis, the mounting frame advantageously comprises guide means which are guided in the guide rails. This brings about the continuous translational movement with utmost accuracy on to the mounting frame in the direction predetermined by the guide rails. 
     Rollers are particularly provided as guide means in the guide rails because the friction is therefore minimized, which is important in the case of several sequentially arranged mounting frames connected together. 
     By arranging receivers on the mounting frame, workpieces can be secured thereon in a directly detachable manner, or indirectly for example in the case of vehicle bodies that are detachably secured on a skid. 
     By having the receivers assume a position that remains unaltered in the movement of direction with respect to a vertical direction during the mounting frame&#39;s translational movement, it is extremely simple to mount a vehicle body using a skid by way of adjacent conveying means located at the same height. 
     All the drive means known from the prior art can be used for the continuous movement of the individual workpieces. In particular, chain drives, traction rope arrangements, threaded rods or self-propelled mounting frames that have their own drive are perfectly suitable. 
     The angle data given in this application should not be regarded as absolute values. Values that deviate by ±10% are also covered by the disclosure. 
    
    
     BRIEF DESCRIPTION OF THE INVENTION 
     With reference to the enclosed drawings, several exemplary embodiments will be described and explained in more detail so as to explain the invention further and to understand it better. 
     FIG. 1 shows a schematic, perspective side view of a system according to the invention in relation to the direction of conveyance of individual vehicle bodies, viewed from the right-hand side, 
     FIG. 2 shows a schematic, perspective side view of the system according to the invention in FIG. 1 when viewed from the direction of conveyance of the vehicle bodies on the left-hand side, 
     FIG. 3 shows a cross-sectional view through a system according to the system in FIGS. 1 or  2 , 
     FIG. 4 shows a schematic, direct side view of the system according to the invention in FIGS. 1 to  3 , 
     FIG. 5 shows a side view of the system according to the invention, in which the dipping process into and raising process out of a treatment bath is schematically depicted, 
     FIG. 6 shows a side view of another embodiment of the system according to the invention, with an additional control guide for pivoting the vehicle bodies, 
     FIG. 7 shows a side view of a vehicle body dipped into the treatment bath in a system according to the invention in a further embodiment with special control guide rails for pivoting the vehicle bodies, 
     FIGS. 8-10 show a depiction of the sequence of horizontally mounting a vehicle body on a skid on to a system according to the invention, 
     FIGS. 11-13 show a sequential depiction of vertically mounting a vehicle body supported on a skid on to a system according to the invention, 
     FIGS. 14-16 show a schematic sequential depiction of mounting a vehicle body without interposing a skid on a purpose-built device according to the system according to the invention, 
     FIG. 17 shows a schematic side view of a dryer in which a height difference between a base level and dryer level is overcome by rotating the vehicle bodies, and 
     FIG. 18 shows a schematic side view of a paint dryer in which a rotation of the vehicle bodies is brought about during a continuous translational movement of vehicle bodies. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     1st Embodiment 
     Structure: 
     A first embodiment of the system according to the invention is shown in FIGS. 1 to  5 . Guide rails  5  extend above a plurality of successively connected treatment baths  20  at the sides thereof. The guide rails  5  are spaced apart from one another and are disposed in parallel above the treatment baths  20 . When viewed in cross section, they each comprise two lateral guide surfaces located on top of one another. The guide rails  5  extend downwards at the end of such an alignment of treatment baths  20  and terminate in return rails  27  disposed beneath the treatment baths  20 . Deflectors  9  are arranged at the reversal points between upper guide rails and lower return rails  27 . 
     Drive means that are not depicted here, such as driven chains, traction ropes, gear rods or the like, extend within the guide rails  5 . These drive means are deflected via the deflectors  9  or other means mated therewith toward the return rails  27  and run back in the return rails  27 . A motor not depicted here continuously drives these drive means at a variable speed. 
     Individual vehicle bodies  1  are each securely connected to a skid  2 . Each skid  2  with a vehicle body  1  mounted thereon is detachably connected to a mounting frame  7 . A plurality of these mounting frames  7 , which are spaced apart, are connected to the drive means that is not depicted here and which extends between the guide rails  5  and return rails  27 . 
     Each mounting frame comprises a rotary axis  13  which runs between the rails  5  across the direction specified by the rails  5 ; i.e. across the direction of movement specified by the drive means along the treatment baths  20 . The rotary axis of a mounting frame  7  is guided by means of for example rollers within the guide rails  5  or the return rails  27 . Two opposing levers  15  are respectively disposed with the rotary axis  13  at each side of the mounting frame  7 . Two levers disposed on one side of the mounting frame  7  are offset through about 180° in relation to one another. On the opposite side of the mounting frame  7 , these levers are rotated with respect to the other side through 90°. Rollers  12  are rotatably disposed at each of the ends of the levers  15 . 
     Specially shaped, directional rails  22  are secured in the area of a side wall  201  of the treatment bath  20  at each side in the area of the upper guide rails  5 . On the one side, the right-hand side in FIG. 1, a directional rail  22  is attached in the area of the side wall  201  of the treatment bath  20 ; this rail has a first horizontal portion, then a downwardly pointing portion angled at approximately 45°, and which then changes into a portion that faces upwards at approximately 45° with respect to a horizontal line. This directional rail  22  then extends horizontally until almost the other end wall  202  of the bath  20 . 
     As is evident from the depiction in FIG. 2 viewed from the left-hand side, the directional rail  23  opposite the aforementioned directional rail  22  in FIG. 1 is first provided with a horizontal portion located below a guide rail  5  on the other side, i.e. here the left-hand side, viewed in the direction of movement of the vehicle bodies. This horizontal portion merges into a portion pointing upwards at about 45°. This is followed by a portion pointing downwards by about 45°. 
     At the end of a treatment bath  20  in the area of a side wall  202 , as shown in FIGS. 1 and 2, directional rails  22 ,  23  are designed in the above-described manner again at both sides of the treatment bath  20 . 
     But at least one directional rail  22 ,  23  is designed to extend horizontally in the area between two side walls  201 ,  202  of a treatment bath  20 . 
     In summary, it should again be emphasized that in the inlet and outlet area of a treatment bath  20 , directional rails  22 ,  23  are each placed opposite one another in a rotated arrangement in relation to two opposite sides; i.e. when an upwardly facing directional rail portion is present on the one side, the directional rail portion disposed on the opposite side of the mounting frame  7  is facing downwards. 
     Function: 
     The rollers  12  disposed at the ends of one lever  15  respectively of the mounting frames  7  roll off on to directional rails  22 ,  23 . A vehicle body detachably secured to the mounting frame  7  and having an interposed skid  2  is rotated in the following manner by the continuous conveyance of the mounting frames  7  within the guide rails  5 . 
     A vehicle body  1  attached to a skid  2  is already detachably secured on a mounting frame. This process will be explained in even more detail later on with reference to FIGS. 8 to  16 . The mounting frame  7  with its vehicle body  1  now mounted thereon is guided in horizontal alignment by the drive means along the guide rails  5  into the inlet area of a treatment bath  20 . A pair of levers  15  is vertically located on the one side of the mounting frame  7 , whereas the opposite pair of levers  15  is aligned horizontally. The horizontally aligned pair of levers  15  rolls on the horizontal directional rail section  22 . As a result, the mounting frame is moved in a manner that maintains the horizontal alignment. The continuous movement of the drive means causes the downwards lever  15  of the upright pair of levers  15  to roll up the short horizontal first portion of the left-hand guide rail  23  on its upper side. The opposite first lever, which previously rolled off on a horizontal guide piece of the right-hand directional rail  22 , is now exactly at the kink of the right-hand directional rail  22  at which point the right-hand rail  22  bends downwards. 
     The continued translational movement now causes the roller  12  of the lever  15  on the left-hand side of the mounting frame  7  to run off on that portion of the left-hand directional rail that points upward at 45°. In consequence, the mounting frame  7  is rotated forward-s in the direction of the translational movement. At the same time, the roller  12  of the lever  15  located on the right-hand side rolls off on the downwardly pointing portion of the right-hand directional rail  22 . The simultaneous rolling off process on the right-hand directional rail  22  and on the left-hand rail  23  causes the rotational process to be controlled and held in check at all times. The mounting frame  7  is, after all, supported on the levers  15  both in the forwards and the backwards direction in relation to the continuous movement. 
     The further rotational process is controlled by the other rising and falling portions of the right-hand directional rail  22  and left-hand directional rail  23 . The body  1  is finally completely dipped in the treatment bath  20  and continues to be continuously conveyed within the treatment bath  20  along the guide rails  5 . 
     At the end of the treatment bath  20 , the roller  12  located at a lever  15  on the left-hand side rolls up the left-hand directional rail  23 . This causes the vehicle body  1  to undergo a process of rotation out of the treatment bath  20 . At the same time, a roller  12  of a lever  15  in turn rolls off on a correspondingly oppositely aligned portion of the right-hand directional rail  22 . This causes the vehicle body  1  to rotate out in a complete and controlled manner. 
     The right-hand directional rail  22  and left-hand directional rail  23  in the area of the side walls  201 ,  202  of a treatment bath  20  and the simultaneous continuous conveyance of a mounting frame  7  in the rails  5  enable the side walls of the treatment bath  20  to be disposed upright or to be inclined very steeply downwards or upwards. 
     The lateral directional rails  22 ,  23  should have a gradient of 45°. Straight directional rails  22 ,  23  can be used in this case without producing any major fluctuations in angular velocity during rotation. 
     The basic structure of a system according to the invention can be easily identified from the cross-sectional view depicted in FIG.  3 . Supports  21  on which the guide rails  5  extend are located next to the treatment bath  20 . As already explained in detail, the mounting frames  7  with the vehicle bodies  1  mounted thereon and secured via a skid  2  are conveyed within these guide rails  5 . The mounting frames  7 , on which levers  15  are provided with rollers  12  located thereon, comprise a rotary axis  13 . The rollers  12  roll off on directional rails  22  and  23 . 
     Beneath the treatment bath, the mounting frames in return rails  27  are returned to their original position, as is particularly apparent from FIG.  3 . 
     2nd Embodiment 
     Structure: 
     Another embodiment of the system according to the invention is evident from FIG.  6 . In the embodiment of the device according to the invention depicted in FIG. 6, an additional control guide rail  24  is disposed in the region of the treatment bath  20 . In contrast to the aforementioned first embodiment of the invention—in which in that area of the treatment bath  20  where the vehicle body  1  is transported through in a completely rotated manner and dipped in the medium of the treatment bath  20  and where the levers  15  were horizontally guided on one of the directional rails  22 ,  23 , thereby making it impossible to rotate the vehicle body  1  into this region of the treatment bath  20 —the directional rail  22  or  23  is now complemented in this area by an additional guide rail  24 . In the side view, the directional rail  22  or  23  and the guide rail  24  have a repeatedly curved pattern. 
     Function: 
     One of the lever arms with the roller  12  rolls off on this guide rail  24 , so that the entire mounting frame with its vehicle body  1  mounted thereon is slightly pivoted to and fro in relation to the rotary axis  13  as a result of the curved pattern of the control guide rail  24 . This makes it possible to rock the vehicle body within the treatment bath, which results in the further reduction of trapped air bubbles caused by the process. 
     3rd Embodiment 
     Structure: 
     In the third embodiment of the invention depicted in FIG.  7  and in contrast to the aforementioned embodiments, the mounting frame  7  is additionally designed with a small, laterally projecting control lever  26  at the end of which a roller  28  is rotatably secured. The roller  28  runs in a control guide rail  25  that extends along a treatment bath  20 . The control guide rail  25  comprises variously curved portions, with the result that rising and falling control portions are present in the guide rail. 
     Function: 
     When the mounting frame  7  is continuously conveyed in the guide rails  5 , the control roller  28  rolls off at the control lever  26  of the mounting frame  7  in the control guide rail  25 . In the case of the upwardly or downwardly inclined portions of the control guide rail, the mounting frame  7  is slightly pivoted to and fro around the rotary axis  13  of the mounting frame  7 . This in turn causes the vehicle body  1  to pivot to and fro, which makes it possible to reduce any air bubbles that may be trapped inside the body  1 . 
     4th Embodiment 
     Structure: 
     FIG. 17 shows a dryer  70  in which vehicle bodies  1  attached to mounting frames  7  are supplied on the previously explained guide rails  2  at a lower level. The vehicle bodies  1  at the mounting frames  7  are suspended with their head pointing down. Directional rails  22 ,  23  are in turn disposed to the left and right of the guide rails  2  in the inlet area of the dryer  70 . These directional rails  22 ,  23  correspond to those directional rails  22 ,  23  already explained in the first to third embodiments. 
     An input opening  71  is located in the inlet area of the dryer  70  in its base at the height of the guide rail  2 . The vehicle bodies  1  are introduced into the dryer  70  through this inlet opening  71  by rotation through approx. 180° around the rotary axis  13  of the respective mounting frame  7 . 
     Function: 
     The vehicle bodies  1  are translationally moved continuously along the guide rails  2 . Rollers  12  disposed on the now horizontal levers of the mounting frame  7  roll off on the horizontally extending directional rail  22 . In this way, the mounting frame  7  is conveyed in the horizontal position with the vehicle bodies  1  suspended over head. As soon as the directional rail  23  is reached, the roller  12  of a vertical lever runs up to it and the mounting frame  7  together with the vehicle body  1  located thereon is rotated clockwise—in the side view represented in FIG.  17 —through the inlet opening  71  into the dryer  70 . The mounting frame is then continuously moved along the guide rails  2  in the dryer  70 , whereby the rollers  12  which are now located on the horizontally aligned levers roll off on the horizontally shaped directional rail  22 . 
     Directional rails  22 ,  23  are in turn arranged in the outlet area, which is not depicted here in FIG. 17, and there is an outlet opening through which the vehicle bodies  1  are rotated out of the dryer  70  by another clockwise rotation. 
     5th Embodiment 
     Structure: 
     In the side view of a dryer depicted in FIG. 18, the directional rails  22 ,  23  that were also used in the other aforementioned embodiments are used to rotate vehicle bodies  1 . The vehicle bodies  1  are detachably secured on mounting frames  81 . The mounting frames in turn comprise a number of levers, at the ends of which rollers  12  are attached. The mounting frames  81  are guided in guide rails  5  extending within the dryer chamber  80 . 
     In contrast to the previously described mounting frames, the mounting frames  81  in use here are designed such that the rotary axis  13  of the mounting frames  81  ends up in the central area of a vehicle body. The mounting frames are equipped for this purpose with a recessed receiver that forms a kind of base trough. The vehicle bodies are also aligned along the rotary axis  13  instead of across it. 
     Function: 
     A vehicle body  1  on a mounting frame  81  is continuously moved in a horizontally aligned manner within the guide rails  5 . The rollers  12  of the horizontal levers roll off on a horizontally aligned section of the directional rail  22 . As soon as a roller  12  of a vertical lever rolls on to the directional rail  23  or a part that rises up it, the mounting frame is rotated clockwise here. The rollers  12  that were previously rolling off on the horizontal section of the directional rail  22  now roll off on a downwardly facing section of the directional rail  22 . By designing the directional rails  22 ,  23 , the vehicle bodies  1  are constantly rotated continuously around the rotary axis  13  of the mounting frame  81 . This makes it impossible for fat edges, which would result in a loss of quality, to form on the freshly coated vehicle bodies  1 . 
     Mounting a Vehicle Body: 
     Various embodiments for mounting a vehicle body onto a device according to the invention will be explained in detail by means of FIGS. 8 to  16  as follows. Each of the mounting options explained in the following can be used with a device according to the invention, as previously explained in detail. 
     A horizontal mounting option for a vehicle body  1  secured on a skid  2  is shown in FIGS. 8 to  10 . A horizontal conveyor  6 , here a roller conveyor, extends in the supply area of the guidance devices  5 , i.e. in an area in which a first deflector  9  is present for the guidance device  5  or for the drive means that runs inside it. The skid  2  is equipped with front and rear receiving means  3 ,  4  which are designed to complement catch devices  10 ,  11  located on the mounting frame  7 . 
     Explanation of the Mounting Process on to the Mounting Frame: 
     The mounting frame  7  with the first catch device pointing upwards is supplied to the supplied skid  2  as a result of the continuous movement of the mounting frame  7  around the deflector  9 . As shown in FIG. 9, the catch device  10  reaches the front receiving means  3  of the skid  2 . As a result of the continuous movement of the mounting frame  7 , the skid  2  with the vehicle body  1  located thereon is now consequently pulled along by the already engaged front receiver  3  of the skid  2 . As is evident from FIG. 10, the rear receiving means  4  of the skid  2  then engages with the rear catch device  11  of the mounting frame  7 . In consequence, the skid  2  is now securely engaged with the mounting frame  7  and is completely pulled down by the conveyor means  6 . The skid is then fixed on the mounting frame using the locking mechanism  8 . 
     To detach the skid, which now contains a treated vehicle body  1 , from the mounting frame  7  in the device&#39;s discharge area, i.e. at the end of the treatment baths  20 , the reverse procedure to the described mounting process is adopted. 
     A vertical supply or detachment means on a mounting frame  7  according to the device according to the invention is shown in FIGS. 11 to  13 . 
     A lift assembly  30  for skids  2  with their vehicle body  1  located thereon is disposed above guide rails  33  in which a mounting frame  35 , with a design similar to the aforementioned one, is guided. This lift assembly  30  can be used to lower or raise a skid  2  vertically. Each mounting frame  35  has levers  36  at which rollers  40  are disposed. Front and rear catch means  38 ,  39  are securely arranged on the mounting frame. The catch means  38 ,  39  engage with correspondingly formed front and rear receiving means  31 ,  32  on the skid  2 . A locking mechanism  34  is located in the area of the mounting frame&#39;s rotary axis  41 . 
     Function of this Lift Assembly 
     The mounting frame  35  is continuously moved in the guide rails  33  in a horizontal alignment along the guide rails  33 . As soon as a mounting frame  35  is located below the skid  2  on the lift assembly  30 , the lift assembly  30  is lowered, thus enabling the front catch means  39  of the mounting frame  35  to enter the correspondingly formed front receiver  31  of the skid  2 . Because the lift assembly  30  has been lowered to such an extent that the skid  2  slightly rests on the mounting frame  35 , the rear catch means  38  is also engaged with the corresponding rear receiving means  32  of the skid  2  during the engagement of the front catch means  37  and is then detachably secured via the locking mechanism  34 . The lift  30  is now moved upwards so as to mount a new vehicle body with skid  2  on to a mounting frame  35  located therebehind. 
     During unloading, the now treated vehicle body is released from the mounting frame  35  and removed upwards by means of a lift device designed as above. 
     FIGS. 14 to  16  show one possible way of horizontally supplying a vehicle body without a skid on to a mounting frame in a system according to the invention. 
     Structure: 
     A conveyor  50  with supports  51  that are individually moveable thereon is arranged above guide rails  62 . Mounting frames  55  guided in the guide rails  62  comprise lockable front and rear catch means  54  which can be introduced into correspondingly formed front and rear receivers  52 ,  53  on a vehicle body  1 . Such a mounting frame  55  in turn comprises lever arms  60  which are fitted with rollers  57 ,  58  in order to act as a guide for the purpose of rotation around a rotary axis  61  while dipping into a treatment bath  20 . 
     Function: 
     A skidless vehicle body  1  is supplied by means of the conveyor  51  to a supply area of the system according to the invention where a mounting frame  55  is moved toward the body  1  from below by means of the drive means in the guide rails  62 , enabling the frame&#39;s catch means  54  to engage with the receivers  52 ,  53  of the vehicle body  1  and allowing them to lock. The conveyor  51  releases the vehicle body and leaves the take-over area. 
     During delivery, a mounting frame  55  takes the vehicle body  1  to the discharge site where the vehicle body is released from the mounting frame  55  and received by the succeeding conveyor  51 . The mounting frame  55  is removed downwards and the vehicle body  1  can be taken away by the succeeding conveyor  51 .