Coating booth for coating vehicle rims

Description

[0001] The present invention relates generally to the coating of workpieces and in particular to the coating of rotationally symmetrical workpieces, especially vehicle rims, with coating material, in particular coating powder.

[0002] According to one aspect of the present invention, it relates to a coating booth optimized for coating such workpieces, while according to another aspect, the invention relates to a system for coating such workpieces.

[0003] Coating booths for coating workpieces, particularly with coating powder, are generally known from the prior art. Such coating booths typically comprise a coating chamber with a booth floor, two opposing workpiece passages, and a conveying device for transporting workpieces to be coated through the coating chamber. The conveying device is usually located below the booth floor and includes a workpiece carrier that projects into the coating chamber through a conveying slot in the booth floor.

[0004] Coating booths with such "floor conveyors" are used particularly for coating high-quality workpieces, as the arrangement of the conveyor system below the booth floor allows for a high level of coating quality. This is primarily because "classic" conveyors for the suspended transport of workpieces through the coating chamber can encourage dirt particles or powder residue to fall from the conveyor system, which can lead to irregularities in the coating.

[0005] German patent application DE 103 59 280 A1 discloses a spray coating device for spraying the face surfaces of vehicle rims with coating powder. The device comprises a floor conveyor with motor-driven, rotatable spindles arranged in series, each supporting one of the vehicle rims on its upper mounting surface. The system includes four spray stations, each equipped with two stationary, non-rotatable spray guns positioned diametrically above a rim. The spray guns are directed vertically downwards to spray coating powder onto the face surface of the vehicle rim below, while the spindle with the vehicle rim rotates around the vertical axis of rotation at the spray station. Two additional stationary, upward-facing spray guns are provided for coating the reverse side of the rim.

[0006] In one embodiment, the forklift operates intermittently, meaning it stops while the rim is being coated. This has the disadvantage that the forklift must be stopped every time a vehicle rim is to be coated. After the rim is coated, the forklift must start up again and then stop once the next rim reaches the coating station.

[0007] In another embodiment, the forklift is continuously moved past the stationary spray guns, even during the coating of the vehicle rims. To ensure the vehicle rims are coated with sufficient coating powder, the forklift must travel extremely slowly.

[0008] Both designs have the disadvantage that the number of vehicle rims that can be coated per unit of time is relatively limited. This can be countered by using a large number of spray stations. However, this has the disadvantage of requiring a relatively large installation space for the entire coating system.

[0009] Further spray coating devices are known from DE 10 2012 214321 A1, EP 3 459 642 A1 and WO 2005 / 058508 A1.

[0010] The present invention is based on the objective of providing a coating booth and a system for coating, in particular rotationally symmetrical workpieces, especially vehicle rims, with coating material, in particular coating powder, wherein the coating booth or the coating system can be used as flexibly and automatically as possible and yet delivers an optimum in productivity and economy.

[0011] This problem is solved with regard to the coating booth by the subject matter of independent claim 1, wherein advantageous further developments of the coating booth according to the invention are specified in the corresponding dependent claims.

[0012] With regard to the coating system, the problem underlying the invention is solved by the subject matter of dependent claim 12, wherein advantageous further developments of the coating system according to the invention are specified in the corresponding dependent claims.

[0013] Accordingly, the invention relates in particular to a coating booth for coating workpieces, especially rotationally symmetrical ones, particularly vehicle rims, with coating material, in particular coating powder, wherein the coating booth comprises a coating chamber and a conveying device for transporting the workpieces to be coated through the coating chamber. The coating chamber of the coating booth according to the invention has a booth floor, two opposing side walls, each with a workpiece passage, two opposing side walls adjoining the side walls with the workpiece passages, and a booth roof opposite the booth floor.The conveying device, which serves to transport the workpieces to be coated through the coating chamber, is located below the cabin floor and has a workpiece carrier which protrudes into the coating chamber of the coating cabin via a conveying slot in the cabin floor.

[0014] The coating booth according to the invention further incorporates an applicator system for spraying coating material as needed within the booth. The applicator system comprises a first gun system for spraying coating material as needed onto a first area of ​​the workpieces to be coated, a second gun system for spraying coating material as needed onto a second area of ​​the workpieces to be coated, and a third gun system for spraying coating material as needed onto a third area of ​​the workpieces to be coated.

[0015] The first gun system of the applicator system is specifically designed to spray coating material onto a visible area of ​​the workpieces to be coated, as needed. The term "visible area" used here refers to the so-called A-side of the workpiece in its intended use. In the case of vehicle rims, the visible area is therefore the outer surface. The second area is, for example, the rim well, and the third area is the side of the vehicle rim opposite the visible side.

[0016] The second gun system of the applicator system is designed to spray coating material, as needed, onto a side area of ​​the workpieces to be coated that is adjacent to the visible area. The third gun system, on the other hand, is designed to spray coating material, as needed, onto a rear area of ​​the workpieces to be coated that is opposite the visible area.

[0017] In the coating booth according to the invention, it is particularly provided that the first gun system is assigned a first axis or positioning system for positioning and / or aligning the first gun system relative to the workpieces to be coated during a coating process. The second gun system is assigned a second axis system for positioning and / or aligning the second gun system relative to the workpieces to be coated during a coating process, while the third gun system is assigned a third axis system for positioning and / or aligning the third gun system relative to the workpieces to be coated.

[0018] According to preferred embodiments of the coating booth according to the invention, the first, second, and third axis or positioning systems are each designed as a system that moves along with the workpieces to be coated during transport through the coating chamber. Each axis or positioning system is movable relative to the coating chamber along the side walls adjacent to the side walls with the workpiece passages, wherein the axis or positioning systems are designed such that they move synchronously or asynchronously to a conveying speed of the conveying device.

[0019] In particular, it is provided that the second and third axis systems are each connected to the correspondingly assigned pistol system via an opening formed in a side wall adjacent to the side walls with the workpiece passages, wherein preferably the second and third axis systems are connected to the correspondingly assigned pistol system via the same opening in a side wall adjacent to the side walls with the workpiece passages.

[0020] According to preferred embodiments of the present invention, it is provided that only the first pistol system performs a movement asynchronous to the running conveyor device, while the second and third pistol systems move synchronously to the conveyor movement.

[0021] The first, second, and third axis systems each preferably have one or more gun systems, and preferably two gun systems each. This allows for a higher throughput of workpieces to be coated, because several workpieces can be coated simultaneously.

[0022] Advantageously, the second and third axis systems have a common transport device for moving the second and third gun systems together relative to the coating chamber and synchronously with the workpieces transported through the coating chamber and to be coated by means of the conveying device.

[0023] In contrast, the first axis or positioning system should have a transport device independent of the second and third axis systems, which is designed to move the first gun system relative to the coating chamber and asynchronously to the workpieces to be coated transported through the coating chamber by means of the conveyor device, and in particular independently of the common transport device of the second and third axis systems.

[0024] According to preferred implementations of the coating booth according to the invention, a robot arm system is assigned to the first axis system, which, with the aid of a robot guide above the conveyor device and in particular above the workpieces to be coated and preferably on the booth roof, can be moved relative to the coating chamber and in particular asynchronously with a transport movement of the workpieces to be coated.

[0025] While preferably a robot arm system is assigned to the first axis or positioning system, a linear positioning system is assigned to each of the second and third axis systems, particularly for the independent positioning and / or alignment of the second and third gun systems relative to the workpieces to be coated.

[0026] Preferably, a control device is associated with the first axis or positioning system, which is configured to control the first axis system and, in particular, a robot arm system associated with the first axis system in such a way that the coating guns of the first gun system each have a predetermined and / or definable position and / or orientation relative to the workpieces to be coated, wherein this predetermined and / or definable position and / or orientation depends in particular on the type and / or size of the workpieces to be coated.

[0027] The first gun system preferably comprises at least one first coating gun and at least one further, second coating gun, wherein the at least one first coating gun is movable and / or alignable relative to the workpieces to be coated independently of the at least one further, second coating gun. The first gun system preferably comprises at least two further coating guns, wherein the at least two further coating guns are movable and / or alignable independently of one another relative to the workpieces to be coated.

[0028] Similarly, it is advantageous for the second gun system to comprise at least one first coating gun and at least one further, second coating gun, wherein preferably the at least one first coating gun is movable and / or alignable relative to the workpieces to be coated independently of the at least one further, second coating gun. Alternatively or additionally, it can be provided that the third gun system comprises at least one first coating gun and at least one further, second coating gun, wherein preferably the at least one first coating gun is movable and / or alignable relative to the workpieces to be coated independently of the at least one further, second coating gun.

[0029] The coating guns are preferably electrostatic coating guns designed to electrostatically charge the coating material to be sprayed. According to preferred embodiments of the coating booth according to the invention, the coating guns are equipped with a control unit for controlling and / or regulating the current levels for charging the coating material. The control unit should, in particular, be designed to regulate current values ​​below 10 µA in increments of at least 0.5 µA.

[0030] With regard to the coating booth, it is advantageously provided that at least partial areas of the booth floor surrounding the conveyor slot are ramped, with at least one air blowing device being provided for preferably pulsed blowing of an airflow along the ramped partial area of ​​the booth floor towards at least one extraction duct provided in the booth floor. Advantageously, the at least one air blowing device is located at the conveyor slot.

[0031] Preferably, at least one additional air blowing device is used on or in at least one side wall of the coating booth that adjoins the side walls with the workpiece passages. This additional air blowing device is particularly designed to blow an airflow, preferably pulsed, along the booth floor towards the at least one extraction channel provided in the booth floor.

[0032] The system according to the invention for coating workpieces, particularly rotationally symmetrical ones, especially vehicle rims, with coating material, particularly coating powder, comprises a coating booth of the aforementioned type according to the invention and a coating material supply for feeding coating material to the gun systems of the applicator system. The coating material supply is specifically designed to feed only fresh coating material to the first gun system and to feed fresh coating material with recovery material or only recovery material to the second and third gun systems.

[0033] The term "recovery material" used herein refers to coating material that has already been sprayed at least once during a coating process and has therefore been recycled. Such recovery material is sometimes also referred to as "overspray" material.

[0034] According to further developments of the coating system according to the invention, it is provided that the coating material supply preferably has at least one coating material pump for each gun system, wherein the coating material pump is preferably based on the dense current principle and is designed for continuous coating material conveying.

[0035] The following describes in more detail an exemplary embodiment of the coating booth according to the invention, with reference to the accompanying drawings.

[0036] They show: FIG. 1 schematically and in a partially cutaway view an exemplary embodiment of the coating booth according to the invention; FIG. 2 schematically a sectional view through a workpiece (here a vehicle rim) with the different areas assigned to the gun systems of the coating booth according to the invention; FIG. 3 a schematically an exemplary positioning of the coating guns of the first gun system for two workpieces to be coated simultaneously; FIG. 3b schematically the arrangement of the coating guns of the first gun system during a coating process of other, smaller workpieces; FIG. 4 a schematically the arrangement of the coating guns of the third gun system of the coating booth according to the invention during a coating process of two workpieces; and FIG.4b schematically shows the alignment and arrangement of the coating guns of the third gun system during a coating process of other, smaller workpieces.

[0037] The invention is described in more detail below in connection with a coating booth 1 for powder coating vehicle rims 2.

[0038] Original equipment manufacturers (OEMs) of passenger car alloy wheels (vehicle rims 2) largely rely on powder-coated surface finishes in industrial production today. The main advantages, such as impact resistance, scratch resistance, high corrosion protection, and ease of maintenance, outweigh the drawbacks. In the powder coating process, in addition to thorough part pretreatment and controlled curing of the powder coating, the powder application itself—that is, the application of the coating powder to the metal surface—is particularly crucial for quality, flexibility, and productivity. The electrostatic charging capability of the coating guns used as sprayers, on the one hand, and a booth system specifically designed for rim coating, on the other, play a decisive role.

[0039] On the other hand, manufacturers of vehicle rims face ever higher demands due to increasing individualization, variety of colors and rim types, diverse sizes and increased quality requirements.

[0040] The coating booth 1 according to the invention, which is described in more detail below with reference to the drawings using an exemplary embodiment, meets these requirements and in particular enables flexible and automated coating with optimum productivity and economy.

[0041] The exemplary embodiment of the coating booth 1 according to the invention, which is shown schematically and in a partially cutaway view in FIG. 1 The system shown essentially comprises a coating chamber, which in turn has a cabin floor 3, two opposing side walls, each with a workpiece passage (in FIG. 1 (not shown), has two opposing side walls 4 adjacent to the side walls with the workpiece passages and a cabin roof 5 opposite the cabin floor 3.

[0042] Furthermore, a conveyor device 6 is used to transport the workpieces to be coated (here vehicle rims 2). The conveyor device 6 is located below the cabin floor 3 and has a workpiece carrier (spindle 7) which projects into the coating chamber of the coating booth 1 via a conveyor slot in the cabin floor 3.

[0043] At least partial areas 18 of the cabin floor 3, which surround the conveying slot, are designed in a ramp shape. Air blowing devices are provided for preferably pulsed blowing of an airflow along the ramp-shaped partial area 18 of the cabin floor 3 in the direction of extraction channels 19 provided in the cabin floor 3.

[0044] Furthermore, additional air blowing devices are preferably provided, which are located on or in at least one side wall 4 of the coating booth 1, which adjoins the side walls with the workpiece passages. This at least one additional air blowing device is designed to blow an airflow, preferably pulsed, along the booth floor 3 in the direction of the at least one extraction channel 19 provided in the booth floor 3.

[0045] The coating booth 1 according to the invention, as illustrated by the example in FIG. 1 The system shown also features an applicator system for spraying coating material as needed in the coating booth 1.

[0046] In this context, it is specifically provided that the applicator system comprises a first gun system 8 with a plurality of coating guns, a second gun system 9 with a plurality of coating guns, and a third gun system 10 with a plurality of coating guns. The coating guns of the first gun system 8 are designed to spray coating material as needed onto a first area 11 of the workpieces to be coated (vehicle rims 2), while the coating guns of the second gun system 9 are used to spray coating material as needed onto a second area 12 of the workpieces to be coated, and the coating guns of the third gun system 10 are used to spray coating material as needed onto a third area 13 of the workpieces to be coated.

[0047] The corresponding areas 11, 12, 13 of workpiece 2, which are assigned to the pistols of the first, second and third pistol systems 8, 9, 10, are illustrated by an example in FIG. 2 shown.

[0048] Accordingly, the guns of the first gun system 8 are used in particular for spraying coating material onto a visible area of ​​the workpieces 2 to be coated, the guns of the second gun system 9 are used, if necessary, to spray the coating material onto a side area (rim bed) of the workpieces 2 adjacent to the visible area, while the guns of the third gun system 10 are used, if necessary, to spray coating material onto a rear area of ​​the workpieces 2 opposite the visible area.

[0049] A first positioning or axis system 14, assigned to the first gun system 8, is used to position and / or align the guns of the first gun system 8. Similarly, a second and third axis system 15 and 16, respectively, are assigned to the second and third gun systems 9 and 10 for positioning and / or aligning the guns of the second and third gun systems 9 and 10 relative to the workpieces 2 to be coated during a coating process.

[0050] As in FIG. 1 As indicated, the second and third axis systems 15, 16 are each connected to the coating guns of the correspondingly assigned gun systems 9, 10 via an opening 17 formed in a side wall 4 of the coating booth 1.

[0051] In particular, the second and third axis systems 15, 16 have a common transport device for moving the second and third gun systems 9, 10 together relative to the coating chamber and synchronously to the workpieces to be coated 2, which are transported through the coating chamber by means of the conveyor device 6.

[0052] The first axis system 14 shows in the FIG. 1 In the embodiment shown of the coating booth 1 according to the invention, a transport device independent of the second and third axis systems 15, 16 is designed to move the first gun system 8 relative to the coating chamber and asynchronously to the workpieces 2 to be coated which are transported through the coating chamber by means of the conveyor device 6.

[0053] As with the second and third axis systems 15, 16, the first axis or positioning system 14 is assigned a linear positioning system for positioning and aligning the coating guns of the first gun system 8.

[0054] Alternatively, it would also be conceivable that a robot arm system for positioning and aligning the coating guns of the first gun system 8 is assigned to the first axis or positioning system 14.

[0055] As in FIG. 3a, b und FIG. 4a, b As indicated, the first and third gun systems 8, 10 each have at least one first coating gun and at least one further, second coating gun, wherein the at least one first coating gun is movable and / or alignable relative to the workpieces 2 to be coated independently of the at least one further, second coating gun of the corresponding gun system 8, 10.

[0056] In particular, it is provided that, with the aid of a suitable control device, the first axis system 14 can be controlled such that the at least one first coating gun and the at least one further, second coating gun each have a predetermined and / or definable position and / or orientation relative to the workpieces 2 to be coated, wherein the predetermined and / or definable position and / or orientation depends in particular on the type and especially on the size of the workpieces 2 to be coated. The same applies, figuratively speaking, to the coating guns of the third gun system 10.

[0057] In the coating booth 1 according to the invention, which is used in particular for powder coating vehicle rims 2, the rim axis is vertically aligned during the powder application, i.e. the vehicle rim is transported in this position through the coating booth 1 by means of a floor conveyor 6 on rotatable spindles 7.

[0058] This suggests that coating booth 1 is specifically designed for rim coating. The focus of the booth concept is on the airflow within booth 1, the capabilities of axle systems 14, 15, and 16, their integration, and, last but not least, the question of throughput.

[0059] Generally, a coating booth 1 requires three openings, two of which serve as entry and exit openings for the vehicle rims 2 passing through. Ideally, these openings also serve as booth access for maintenance purposes.

[0060] The lateral third cabin opening 17 is the actual coating access of the individual guns of the second and third gun systems 9, 10, which are mounted on an axle system 14, 15, 16, to the vehicle rim 2.

[0061] In addition to these physical requirements, the openings 17 also fulfill the requirements for airflow through the coating booth 1. Starting from a filter system that extracts overspray powder through the air ducts within booth 1, ambient air flows into booth 1 through the booth openings. The resulting airflows prevent powder from escaping booth 1. The incoming air must not impede the coating process. The side booth opening 17 is appropriately sized for use with moving axis systems 14, 15, 16 or with robots.

[0062] On the other hand, the requirement for uniform and steady airflow in the area of ​​active powder application to the vehicle rim 2 is crucial for the coating result. The vehicle rim 2 is preferably coated over approximately 75% of the total cabin length by the moving coating guns. Changes in airflow conditions are to be expected, particularly at the cabin entrances and exits.

[0063] The floor conveyor 6, which runs through the coating booth 1, is separated from the interior of the coating booth 1 by an enclosure 18, which can be removed for maintenance purposes. The spindle feedthrough itself is also sealed to prevent coating powder from falling onto the floor conveyor 6.

[0064] The enclosure 18 and the floor 3 of the coating booth 1 are automatically and intermittently cleaned of coating powder by several air blower bars. The powder is then fed back into the powder cycle as recycled powder. The air blower bars emit pulses of air along the floor surfaces, pushing the excess powder towards the extraction slot or extraction duct 19. This process is more efficient and saves energy compared to a continuously active blow-off system.

[0065] In the coating booth 1 according to the invention, the workpieces (vehicle rims 2) are coated with powder relative to the conveyor movement. This achieves a higher throughput from the outset than with a stop-and-go operation.

[0066] During the coating process, an axis system moves all coating guns relative to the conveyor movement (i.e., the movement of the vehicle rims 2). The rim 2 itself rotates around its own axis. The required conveyor speed and the length of the booth 1 can be determined using the coating time of one vehicle rim 2 and the planned throughput per hour.

[0067] For a planned future increase in throughput, the same approach can be used as a first step to determine the maximum conveying speed that allows for a specific booth length. Alternatively, and more efficiently, a second set of spray guns can be installed on the existing axle system. This allows two vehicle rims (2) to be coated simultaneously, essentially doubling the throughput while maintaining booth 1. The advantage of this application is that the individual coating parameters, such as conveyor speed, rim rotation, powder output, high voltage and current for powder charging, and coating programs, can be reused, thus leveraging existing experience.

[0068] Viewed from the outside, a powder cloud forms along the vehicle rim 2 to be coated during the coating process. The powder-spraying guns move relative to the conveying direction of the vehicle rim 2, which means the powder cloud is oriented relative to the vehicle rim 2. The three rim areas 11, 12, 13 are covered according to... FIG. 2 (Visible surface with holes, inner surface and rim bed) each assigned a pistol group 8, 9, 10.

[0069] Each of these groups 8, 9, 10 is coated with individual coating parameters. The distances to the vehicle rim 2, the orientations of the gun and their number depend on the rim type (design, size and coating requirements or powder type).

[0070] Ideally, a coating system knows the type of rim to be coated and is able to automatically retrieve the necessary system settings from stored programs. The electrostatic coating parameters are stored in the system control as programs according to wheel or rim type.

[0071] Ideally, a complex axis system is available for positioning the individual guns or gun groups 8, 9, 10. This allows each wheel or rim type to be coated with the ideal gun positions and number of guns. For example, unused coating guns can be parked outside the work area when coating small workpieces (see figure). FIG. 3b und FIG. 4b ).

[0072] For the highest quality finish, especially on the visible surfaces of workpieces 2, the currents for powder charging should be precisely adjustable in the low range (less than 10 µA) to fully utilize the properties of the coating powder. Additionally, the deliberate removal of excess free ions optimizes the uniformity of the coating pattern, i.e., it prevents induced charges in the powder and avoids the formation of an orange peel effect.

[0073] In particular, only a certain amount of charge is needed, and each powder type has a different ideal amount to achieve optimal coating quality. Overcharging the coating powder reduces application efficiency and tends to lead to surface defects. This is due to excessively high field line concentrations or an excessively high ion flux per unit of time and area. In easily accessible areas, back-ionization occurs (orange peel effect from back-spray), while in more shielded areas, the result is an excessively thin powder layer.

[0074] Overcharging the powder should be avoided, as this not only wastes the coating powder's potential but may even destroy it. To achieve optimal properties, precise current control below 10 µA is necessary to control the powder's charge level and thus improve the optical surface quality. Control in 0.5 µA increments is particularly advantageous.

[0075] Working with small charging currents also has the effect that the powder can be deposited better in depressions, which is particularly noticeable in rim holes or spoke spaces.

[0076] To convey powder from a storage container to the coating guns, so-called injectors based on the Venturi principle can be used. However, with this technology, the conveying stability is highly dependent on the condition of the injector's internal, powder-contacting components, which are considered wear parts. At the high speeds inherent in the technology, the coating powder acts abrasively, which ultimately leads to a deviation in the conveying rate even over a short period and consequently necessitates the replacement (maintenance stoppage) of the affected parts.

[0077] To avoid this, pumps are preferably used for powder conveying. This conveying technology does not exhibit such wear and tear. The powder delivery rate remains stable and does not change even over long periods.

[0078] To achieve the required powder output for coating, the aforementioned fluctuations must be taken into account when using an injector. This means that the actual output is consistently higher than the target value. This is not only problematic with regard to reproducible layer thicknesses but also results in unnecessary powder waste.

[0079] The properties of a coating powder are best preserved during conveying when the powder can flow as freely and homogeneously as possible without physical interference. Abrupt changes in direction, accelerations, excessive speeds, or tight bending radii are all factors that can alter the properties of a coating powder. The coating powder must arrive at the atomizer of the coating gun in as close to its original state as possible for optimal charging, correct cloud formation, and ultimately, the creation of the required powder layer.

[0080] Therefore, powder pumps mounted directly on the powder container are preferred, resulting in an extremely short and rigid suction path. Once at the powder pump, a perfectly straight and step-free powder channel within the pump ensures gentle powder transport, which is particularly beneficial for sensitive powder types such as metallic or textured powders.

[0081] The atomizing air is added directly at the coating gun and is therefore completely separate from the powder transport. This enables ideal formation of the powder cloud in terms of shape and velocity, while simultaneously preventing a pulsating powder cloud and thus uneven powder loading, which leads to irregularities in the coating appearance.

[0082] Preferably, at least two powder circuits are provided, wherein the powder supply of a first pistol group is only with fresh powder and a further pistol group is supplied with a fresh / recirculated powder mix.

Claims

1. A coating booth (1) for coating in particular rotationally symmetric workpieces (2), particularly vehicle rims, with coating material, in particular coating powder, the coating booth (1) comprising: - a coating chamber having a booth floor (3), two oppositely positioned side walls, each having a workpiece passageway, two side walls (4) oppositely positioned and adjoining the side walls with the workpiece passageways and a booth roof (5) positioned opposite from the booth floor (3); - a conveyor device (6) for transporting the workpieces (2) to be coated through the coating chamber, wherein the conveyor device (6) is arranged beneath the booth floor (3) and has a workpiece carrier (7) which extends into the coating chamber of the coating booth (1) through a conveyance slot in the booth floor (3); and - an applicator system for spraying coating material within the coating booth as needed, wherein the applicator system comprises a first gun system (8) for spraying coating material as needed onto a first area (11) of the workpieces (2) to be coated, a second gun system (9) for spraying coating material as needed onto a second area (12) of the workpieces (2) to be coated, and a third gun system (10) for spraying coating material as needed onto a third area (13) of the workpieces (2) to be coated, characterized in that the first gun system (8) is assigned a first axis system (14) for the positioning and / or aligning of the first gun system (8) relative to the workpieces (2) to be coated during a coating procedure, wherein the second gun system (9) is assigned a second axis system (15) for the positioning and / or aligning of the second gun system (9) relative to the workpieces (2) to be coated during a coating procedure, and wherein the third gun system (10) is assigned a third axis system (16) for the positioning and / or aligning of the third gun system relative to the workpieces (2) to be coated during a coating procedure, and wherein the first, second and third axis systems (14, 15, 16) are each designed as a system which travels along with the workpieces (2) to be coated as the workpieces (2) to be coated are transported through the coating chamber, wherein each axis system (14, 15, 16) is movable relative to the coating chamber along the side walls (4) adjoining the side walls with the workpiece passageways, wherein the axis systems (14, 15, 16) are designed so as to move synchronously with a conveying speed of the conveying device (6).

2. The coating booth (1) according to claim 1, wherein the first gun system (8) is designed to spray coating material as needed onto a visible area of the workpieces (2) to be coated, wherein the second gun system (9) is designed to spray coating material as needed onto a side region of the workpieces (2) to be coated adjacent to the visible area, and wherein the third gun system (10) is designed to spray coating material as needed onto a rear area of the workpieces (2) to be coated opposite from the visible area.

3. The coating booth (1) according to claim 1 or 2, wherein the second and third axis system (15, 16) are each connected to the respectively assigned gun system (9, 10) via an opening (17) formed in a side wall (4) adjacent to the side walls with the workpiece passageways, wherein the second and third axis system (15, 16) are preferably connected to the respectively assigned gun system (9, 10) via the same opening (17) in a side wall (4) adjoining the side walls with the workpiece passageways.

4. The coating booth (1) according to one of claims 1 to 3, wherein the second and third axis system have a common transport device for jointly moving the second and third gun system relative to the coating chamber and synchronously with the workpieces (2) to be coated transported through the coating chamber via the conveyor device (6); and / or wherein the first axis system (14) has a transport device independent of the second and third axis system (15, 16) which is designed to move the first gun system (8) relative to the coating chamber and in particular asynchronously to the workpieces (2) to be coated transported through the coating chamber via the conveyor device (6) and in particular independently of the joint transport device of the second and third axis wherein the first axis system (14) is assigned a robotic arm system able to be moved together with the first gun system (8) over the conveyor device (6) and in particular over the workpieces (2) to be coated relative to the coating chamber and in particular relative to the workpieces (2) to be coated with the aid of robotic guidance; and / or wherein the second and third axis system (15, 16) are each assigned a linear positioning system for the in particular independent positioning and / or aligning of the second and third gun system relative to the workpieces (2) to be coated.

5. The coating booth (1) according to one of claims 1 to 4, wherein the first gun system (8) comprises at least one first coating gun and at least one further second coating gun, and wherein the first axis system (14) is assigned a control device designed to control the first axis system (14) such that the at least one first coating gun and the at least one further second coating gun each have a predefined and / or definable position and / or alignment relative to the workpieces (2) to be coated, wherein the predefined and / or definable position and / or alignment depends in particular on the type and / or size of the workpieces (2) to be coated.

6. The coating booth (1) according to one of claims 1 to 5, wherein the first, second and third axis system (14, 15, 16) are configured such that only the first gun system (8) moves asynchronously to the traveling conveyor device whereas the second and third gun system (9, 10) move synchronously with the conveyor movement.

7. The coating booth (1) according to one of claims 1 to 6, wherein the first gun system (8) comprises at least one first coating gun and at least one further second coating gun, wherein the at least one first coating gun is movable and / or alignable relative to the workpieces (2) to be coated independently of the at least one further second coating gun.

8. The coating booth (1) according to claim 7, wherein the first gun system (8) comprises at least two further coating guns, wherein the at least two further coating guns are movable and / or alignable relative to the workpieces (2) to be coated independently of each other.

9. The coating booth (1) according to one of claims 1 to 8, wherein the second gun system (9) comprises at least one first coating gun and at least one further second coating gun, wherein the at least one first coating gun is preferably movable and / or alignable relative to the workpieces (2) to be coated independently of the at least one further second coating gun; and / or wherein the third gun system (10) comprises at least one first coating gun and at least one further second coating gun, wherein the at least one first coating gun is preferably movable and / or alignable relative to the workpieces (2) to be coated independently of the at least one further second coating gun.

10. The coating booth (1) according to one of claims 7 to 9, wherein the coating gun is an electrostatic coating gun designed to electro-statically charge the coating material to be sprayed with the coating gun, wherein the coating gun is assigned a control device for the controlling and / or regulating of the currents in the coating material charging process.

11. The coating booth (1) according to one of claims 1 to 10, wherein at least sections (18) of the booth floor (3) surrounding the conveyance slot are of ramped design, wherein at least one air blowing device is provided for the preferably pulsed blowing of a flow of air along the ramped section (18) of the booth floor (3) off toward at least one extraction duct (19) provided in the booth floor (3).

12. The coating booth (1) according to claim 11, the at least one air blowing device is provided at the conveyance slot, and wherein at least one further air blowing device is provided on or in at least one side wall (4) of the coating booth (1) adjoining the side walls with the workpiece passageways which is designed to blow a preferably pulsed flow of air along the booth floor (3) off toward the at least one extraction duct (19) provided in the booth floor (3).

13. A system for coating in particular rotationally symmetric workpieces (2), in particular vehicle rims, with coating material, in particular coating powder, the system comprising: - a coating booth (1) according to one of claims 1 to 12; and - a coating material supply for supplying coating material to the gun systems (8, 9, 10), wherein the coating material supply is designed to only supply fresh coating material to the first gun system (8) and to supply fresh coating material along with recovery material or only recovery material to the second and third gun system (9, 10).

14. The system according to claim 13, wherein the coating material supply preferably has at least one coating material pump for each gun system (8, 9, 10), wherein the coating material pump is based on the dense flow principle and designed for continuous coating material conveyance.

15. The system according to claim 14, wherein the coating material pump is a dense phase pump having at least one pump chamber, wherein the at least one pump chamber is provided in a perfectly straight and non-interrupted powder channel of the coating material pump.