EP4137235B1 - Coating device - Google Patents

Description

The invention relates to a coating device according to the preamble of claim 1.

Such coating devices are known from the prior art and are used for the surface application of a coating agent to a workpiece. The coating agent can be, for example, varnish, in particular clear varnish or pigmented varnish, stain or paint. The workpiece is, for example, a wood material part or an assembly of such parts for the manufacture of furniture. For coating, the workpiece is placed on a workpiece holder and then provided with the coating agent by means of a plurality of moving spray units.

In order to achieve high productivity, it has proven to be a good idea in the state of the art to design coating devices with a machine frame and a rotation unit that can be rotated relative to the machine frame. The machine frame includes the workpiece holder mentioned above, while the rotation unit includes the plurality of spray units also mentioned above. When the rotation unit is rotated relative to the machine frame, the spray units cover the workpiece and distribute the coating agent onto the workpiece surface.

A design challenge that must be overcome in known coating devices is to supply coating agent from a fixed coating agent source for the moving rotation unit and the to provide spray units arranged thereon. For this purpose, swivel joints are usually used, each of which has a fixed and a rotatable swivel joint part.

The fixed swivel joint part is arranged on the machine frame, while the rotatable swivel joint part is arranged on the rotation unit. The swivel joint parts mentioned are connected to one another in a sealing manner to form a coating agent channel. At the same time, the swivel joint parts can be rotated relative to one another, whereby the fluid-conducting coating agent channel remains independent of the relative angle of rotation between the swivel joint parts. The fixed swivel joint part comprises an inlet-side connection for the coating agent channel, to which the coating agent source is connected. The rotatable swivel joint part comprises a connection for providing the coating agent for the spray units on the rotation unit.

From the US 2006/0060677 A1 It is known to arrange a pump on the rotary unit. The pump is connected on the suction side to the coating agent source via the rotary joint and on the pressure side to the spray units. In comparison to an arrangement in which the pump is not arranged on the rotary unit but on the machine frame, the arrangement according to US 2006/0060677 A1 to increase the service life of the swivel joint used. This is because the coating agent is not fed through the swivel joint under high pressure. Instead, the coating agent is fed downstream to the swivel joint and then pressurized by the pump and pumped to the spray units. This protects the seals of the swivel joint in particular. This leads to the swivel joint remaining sealed for longer.

Documents US A1, EP 2 123 363 A1 , JP 2003 251234 A and US 10 060 027 B2 disclose further examples of coating devices.

Due to the ever-increasing variety of workpieces to be coated, especially furniture parts, it is desirable to be able to easily change the operating mode of the coating device if necessary. This includes For example, an individually adaptable configuration of the coating agent output depending on the individual dimensions or the material used for the workpieces to be coated.

However, one disadvantage of known coating devices is that they are usually designed as special constructions that are primarily used to coat similar workpieces. It is possible to adapt the design parameters of the coating device, such as the number of spray units and their movement path and speed, to changing operating conditions. However, the required design effort is too high to be able to respond in an economically efficient manner to the high variety of workpieces to be coated.

In particular, a high level of design effort is required if actively controllable components, such as control elements for the coating agent dispensing, are to be retrofitted. This is because an increasing number of such components usually requires a correspondingly high number of control lines, which must be routed from the machine frame to the rotation unit in a complex manner. If the components to be controlled require a power supply for their operation, additional power lines must also be routed from the machine frame to the rotation unit in a structurally complex manner. This makes the coating device technically complex and therefore expensive.

The object underlying the invention is to provide a coating device which is highly adaptable to changing operating conditions, has good controllability and at the same time has a simple structure.

The object is achieved by a coating device according to claim 1. Advantageous further developments can be found in the dependent subclaims. These subclaims contain combinations of features which can also be used independently from the characterising part of claim 1 and without its features can be independent inventions, optionally in combination with features of other subclaims.

The coating device according to the invention comprises a machine frame with a workpiece holder, a coating agent source and a compressed air source. The coating device also comprises a rotation unit that can be rotated relative to the machine frame and has a pump and a plurality of spray units, the pump being connected on the suction side to the coating agent source via a fluid-conducting rotary joint and on the pressure side to the spray units.

According to the invention, the rotation unit has a pneumatic valve device. Furthermore, the spray units each have a compressed air-controlled valve for controlling the output of coating agent. The valve device is connected on the supply air side to the compressed air source at least via a fluid-conducting rotary union and on the exhaust air side to the compressed air-controlled valves of the spray units.

The invention is based on the finding that the arrangement of an additional component in the form of the pneumatic valve device on the rotation unit leads to an overall simple construction of the coating device and at the same time improves its controllability.

The simple design of the coating device results from the fact that a rotary union known per se can be used to provide compressed air for the pneumatic components of the rotary unit. The rotary union preferably has only one compressed air channel, which allows a pneumatic connection between the compressed air source of the machine frame and the rotary unit, independent of the angle of rotation. For this purpose, the rotary union can have an overall simple, robust and structurally compact design: A fixed part of the rotary union is arranged on the machine frame and is fluid-conducting via an inlet connection. connected to the compressed air source. A movable part of the rotary union is arranged on the rotary unit and is connected to the fixed part of the rotary union in a sealing and relatively rotatable manner, forming a fluid path. The fluid path between the two parts of the rotary union remains independent of the angle of rotation between the fixed and the movable part of the rotary union. The fluid path opens into an exhaust air connection of the movable part, which is connected to the valve device.

By means of the valve device, the compressed air flow provided via the rotary union can be distributed to a large number of pneumatically controlled and/or pneumatically operated components, which can be arranged on the rotary unit as required and in large numbers. The arrangement of the valve device on the rotary unit facilitates the simple design of the rotary union. Preferably, as already explained above, the compressed air can be guided from the compressed air source to the rotary unit via just one compressed air channel and distributed by means of the valve device to a large number of compressed air lines on the exhaust air side. The said compressed air lines lead to the valves of the spray units and can be designed to be comparatively short due to the arrangement of the valve device on the rotary unit. This improves the controllability of the valves.

It is within the scope of the invention that the compressed air flow between the rotary feedthrough and the valve device can be divided into several partial flows in order to be able to supply other pneumatic components on the rotary unit with compressed air independently of the valve device. It is also within the scope of the invention that in addition to the rotary feedthrough, other pneumatic components can be arranged in the pneumatic connection between the compressed air source and the valve device.

Preferably, the valve device is designed as a valve island. Such a valve island can be equipped in a flexible manner and as required with a large number of so-called valve discs, which can be adapted to the type and number of the pneumatic components of the rotary unit that are to be driven and/or controlled can be adapted. For this purpose, the valve island usually has a distributor bar with a central air supply connection. The distributor bar also has a large number of distributor connections through which the valve discs are supplied with compressed air. This means that the compressed air for the valves to be controlled can be provided in a structurally compact manner.

In an advantageous further development, the pump for the coating agent is designed to be operated with compressed air and is connected to the compressed air source at least via the rotary union.

According to the development described above, the compressed air is used both to control the dispensing of coating agent and to drive the pump. It is therefore an advantage that the use of different types of energy and signal transmission can be dispensed with and compressed air is used both for control and as an energy source.

It is within the scope of the advantageous development that the compressed air-operated pump is connected to the rotary feedthrough via the pneumatic valve device and is preferably controllable by means of the valve device. Preferably, however, the pump is operated independently of the pneumatic valve device and connected to the rotary feedthrough via a pneumatic branching element, which can be designed as a T or Y piece, for example. The pneumatic branching element can be arranged in a simple manner in a compressed air line between the rotary feedthrough and the valve device. As a result, a compressed air flow can be guided to the rotary unit via the rotary feedthrough and divided between the valve device and the pump by means of the pneumatic branching element. This has the advantage, among other things, that the compressed air flow required for the pump is not limited by the valve device. Furthermore, the valve device can be designed to be compact, since its air-conducting areas and their cross-sections do not have to be dimensioned depending on a required compressed air flow for the operation of the pump.

In an advantageous development, the machine frame comprises an electrical control unit and the pneumatic valve device is designed to be electrically controllable. Furthermore, the rotary feedthrough has at least one signal line. The control unit and at least the valve device are connected to one another via this signal line of the rotary feedthrough.

According to the development described above, the rotary union is not only fluid-conducting, but also designed to transmit signals. Such a design does not contradict a simple structure of the simple rotary union according to the invention. Rather, the signal line for transmitting electrical signals can be designed in a simple manner in the form of an electrical sliding contact between the fixed and the moving part of the rotary union. It is within the scope of the advantageous development that the signal line is multi-pole and accordingly several sliding contacts are formed in the rotary union. Furthermore, it is within the scope of the advantageous development that the signal line is designed as an optical signal line for transmitting optical signals. For this purpose, the parts of the rotary union that can be rotated against each other are connected to one another in terms of signaling via optical coupling elements. Preferably, the electrical control unit and the valve device each have at least one optoelectronic element by means of which electrical signals can be converted into optical signals and vice versa.

The control unit can be designed as a control computer or as a programmable logic controller, which can be operated either alone or in a control network with other control units. A control program is preferably implemented on the control unit, which represents the control logic with which at least the valve device and thus the valves of the spray units can be controlled. If the compressed air supply to the pump is via the valve device, the pump can preferably also be controlled via the valve device.

In a simple embodiment, the control unit is used to output control signals in the form of control voltages, preferably in the range of 0-24 volts. These voltages can be provided directly to the valves of the valve device via the control line of the rotary union in order to control them. After the voltage drops, the valves in question can be brought into an unactuated basic position, for example by means of a spring return. In principle, no electrical power supply is required for the operation of the valve device in addition to the electrical control signals.

The valve device can have at least one analog and/or digital signal input. This signal input serves to receive control signals from the control unit, by means of which the compressed air distribution on the rotary unit can be controlled. A plurality of signal inputs can be spatially combined in a multi-pole connection, the poles of which are each connected to a valve of the valve device in order to control it directly. This is particularly conceivable if the valve device is designed as a valve island.

The coating device preferably has a workpiece detection unit which is designed to detect the presence and preferably also the dimensions of the workpiece to be coated and to output a control signal to the control unit as a function of this. The control unit evaluates the control signal and outputs one or more opening signals to the valve device in order to preferably only open the valves of those spray units which are located above the workpiece. In this way, coating agent can only be output in the area of the workpiece to be coated and thus with high efficiency.

It is also within the scope of the advantageous development that a rotation angle sensor is designed to detect the rotation position of the rotation unit relative to the machine frame and to measure a measured rotation angle to the control unit. Preferably, the control unit stores the positions of the spray units on the rotation unit. Thus, depending on the detected angle of rotation, it can be determined which of the spray units is in the area above a workpiece to be coated. In this case, it is not absolutely necessary for the coating device to have a workpiece detection unit by means of which the presence or dimensions of the workpiece to be coated are detected. Instead, coating agent can be dispensed whenever one or more of the spray units sweep over a defined area of the workpiece holder. Coating agent can thus be dispensed regardless of whether or not there is a workpiece to be coated in this swept area. Such an arrangement is particularly advantageous when the workpieces to be coated are placed in the coating device in large numbers and with small distances from one another.

It is within the scope of the advantageous development that at least one other component located on the rotary unit is also controlled via the control line of the rotary union. In a simple manner, the rotary union can output the corresponding control signals via the control line to the valve device, which passes the signals on to the other components to be controlled. However, it is also within the scope of the advantageous development that the valve device is not located in the signal path between the rotary union and the other components to be controlled. In a simple manner, bus communication can be provided so that the signal path between the rotary union and the valve device can be split in order to be able to control the other components to be controlled with little wiring effort and preferably only one signal line of the rotary union.

In an advantageous further development, the rotary union is designed for electrical energy transmission. Furthermore, the machine frame comprises an electrical voltage source which is at least connected to the valve device via the rotary union.

The valve device is preferably equipped with components that require a permanent power supply, e.g. a microcontroller or another data processing unit. It is also possible to provide at least one analog-digital converter or a sensor on the valve device. In addition, the valve device can be designed in such a way that communication with the control unit can take place using standardized protocols such as TCP-IP and in real time. In order for electrical energy to be provided from the electrical voltage source for the valve device and preferably other components on the rotary unit, the rotary feedthrough preferably has an electrical power line for electrical energy transmission in addition to the signal line. The electrical power line is preferably designed as a two-pole sliding contact. The power line is connected to the electrical voltage source on the one hand and to the valve device on the other. Additionally or alternatively, wireless energy transmission using the rotary feedthrough is also conceivable. In this case, the electrical energy can be transmitted through non-wired electromagnetic fields, in particular by means of inductive and/or capacitive coupling, instead of along a power line and by means of electrical contacts. In another advantageous development, at least the electrically controllable valve device and the control unit are connected to one another in terms of signaling by means of a wireless transmitter-receiver arrangement.

Due to the development described above, the transmission of control signals from the control unit to the valve device can be carried out wirelessly and independently of the rotary feedthrough. The transmitter-receiver arrangement comprises at least a first communication element, which is connected to the control unit, and a second communication element, which is connected to the valve device, wherein the two communication elements serve for the wireless transmission of control signals. Preferably, the second communication element can also be connected to another electrically controllable component on the rotation unit must be signal-connected.

It is within the scope of the advantageous development that the first communication element is a radio transmitter and the second communication element is a radio receiver in order to be able to communicate control signals wirelessly from the control unit to the valve device. Alternatively, the first and second communication elements can each be designed as WiFi or WLAN modules, whose signal communication takes place via a common network in which they are operated. The first communication element can be connected to the voltage source on the machine frame for energy supply. The second communication element arranged on the rotation unit can have its own energy storage device, e.g. in the form of an electric battery.

In an advantageous development, a pneumatically operated, electric generator is arranged on the rotation unit, which is connected to the compressed air source at least via the rotary feedthrough and is designed to supply at least the valve device with electrical energy.

According to the development described above, the rotary union serves to provide a compressed air flow for the compressed air-operated generator. This converts this compressed air flow into electrical energy. This makes it possible to design the rotary union without the possibility of transmitting electrical energy and to operate the electrically operated components of the rotary unit, preferably independently of a stationary voltage source on the machine frame. In order to ensure an uninterrupted electrical energy supply to the rotary unit, an electrical accumulator can serve as an electrical buffer. The battery can preferably be charged using the generator. If necessary, other components on the rotary unit that require an electrical energy supply can also be supplied with electrical energy using the generator and/or the battery.

In an advantageous development, the pump is connected to the rotary union on the supply air side at least via a pump pressure regulator. The pump pressure regulator is preferably designed to be electrically controllable.

The pump pressure regulator is used to regulate a possibly fluctuating inlet pressure of the compressed air provided by the rotary union to a constant and usually lower outlet pressure. The pump pressure regulator preferably comprises a so-called pressure booster in order to regulate the inlet pressure to a higher outlet pressure.

Since the output of coating agent from the spray units is directly dependent on the pump pressure, the quality of the coating result can also be optimized by regulating the pump drive pressure in this way.

The pump pressure regulator can be designed in a simple manner as a mechanical component, whereby the output pressure to be regulated can be set manually and directly on the pump pressure regulator in a manner known per se. The pump pressure regulator is preferably designed as an electrically controllable component. The control unit is designed to output a control signal for regulating the output pressure. If the rotary union has a signal line, the control signal can be output from the control unit to the pump pressure regulator via the rotary union. The valve device can be located in the signal path between the pump pressure regulator and the rotary union. If the coating device has a wireless transmitter-receiver arrangement, this can be used to transmit the control signal from the control unit to the pump pressure regulator. It is also within the scope of the advantageous development that the pump pressure regulator is pneumatically controllable and is preferably controlled via the valve device.

Preferably, the control unit is connected to an easy-to-use input element, e.g. a tablet or the control panel of the coating device. This makes it easy to specify the output pressure to be regulated.

If the pump is connected to the rotary union via the valve device in order to be supplied with compressed air, the pump pressure regulator can advantageously be integrated into the valve device on the exhaust air side. In this case, the control signal from the control unit can be sent to the valve device, which outputs the control signal directly or in processed form to the pump pressure regulator. In particular, the valve device can comprise an analog-digital converter in order to convert the control signal for the pump pressure regulator.

If the pump is connected to the rotary feedthrough via the pneumatic branching element in order to be able to operate independently of the valve device, the pump pressure regulator is preferably arranged between said branching element and the pump. In this arrangement, the pump pressure regulator preferably also serves to control the pump operation. For this purpose, an output pressure to be set can be transmitted to the pump pressure regulator as required by means of a corresponding control signal. For example, the specified output pressure corresponds to 0 bar when the pump operation is to be stopped. Accordingly, the output pressure to be set can correspond to 4 bar, for example, in order to start the pump operation. In this embodiment, the compressed air supply to the pump and the pump pressure regulator is independent of the valve device. Nevertheless, the valve device can be located in the signal path between the control device and the pump pressure regulator and can also output signals to electrically controllable components of the rotary unit that are not pneumatically connected to the valve device.

It is also within the scope of the advantageous development that the pump pressure regulator can comprise a measuring element which is used to measure the regulated pump pressure and output it to the control unit. This allows the operation of the pump to be monitored during the coating process.

Any electrical voltage required to operate the electrically controllable pump pressure regulator can be provided in a simple manner via the rotary union or via the compressed air-operated generator on the rotary unit. Preferably, the valve device can also be used to provide electrical energy for the pump pressure regulator or other electrical components located on the rotary unit.

In an advantageous development, a coating agent pressure regulator is arranged between the pump and at least one of the spray units, wherein the coating agent pressure regulator is preferably designed to be electrically controllable.

The coating agent pressure regulator serves to regulate the pressure of the coating agent relative to the delivery pressure of the pump to an adjustable output pressure and, if necessary, to reduce the delivery pressure applied or to increase it using a pressure booster. The coating agent pressure regulator can be designed in a simple manner as a mechanical component in which the output pressure can be manually adjusted. Alternatively, the coating agent pressure regulator can be pneumatically controlled. If the coating agent pressure regulator is designed to be electrically controllable, control signals can be output from the control unit to the coating agent pressure regulator via the signal line of the rotary feedthrough or via the wireless transmitter-receiver arrangement. It is within the scope of the advantageous development that the valve device is located in the signal path between the control unit and the coating agent pressure regulator. Any electrical voltage required to operate the electrically controllable coating agent pressure regulator can be provided via the rotary union or via the compressed air-operated generator in a similar way to the statements regarding the pump pressure regulator.

In an advantageous development, the spray units each have a compressed air-operated atomizer unit for atomizing the coating agent, wherein the atomizer unit is connected to the compressed air source at least via the rotary feedthrough.

The atomizer unit is used to convert the dispensed coating agent into a large number of finely distributed drops using compressed air. This allows the coating agent to be distributed homogeneously on the workpiece surface and the coating quality to be optimized. The atomizer unit can be operatively connected to the spray unit in different ways for this purpose. It is within the scope of the advantageous development that the atomizer unit has at least one compressed air outlet which is arranged behind a coating agent dispensing opening of the spray unit in relation to the flow direction of the coating agent. The compressed air outlet is preferably designed as an annular gap. Additionally or alternatively, the compressed air outlet can be designed as one or more holes which are located laterally behind the coating agent dispensing opening of the spray unit. It is also within the scope of the advantageous development that the atomizer unit and the spray unit are structurally combined and arranged in a common housing or are structurally separate from one another.

It is within the scope of the advantageous development that the atomizer unit is pneumatically connected to the rotary feedthrough via the valve device. The operation of the atomizer unit can be controlled by means of the valve device. Alternatively, the atomizer unit is connected to the rotary feedthrough via the pneumatic branching element described above or another branching element and is operated independently of the pneumatic valve device. For this purpose, the pneumatic branching element can be designed as a T-piece or as a comparable pneumatic component in the manner already described in order to divide the compressed air flow, which is provided for the rotation unit by means of the rotary feedthrough, at least between the valve device and the atomizer unit.

In an advantageous development, an atomizer pressure regulator is arranged between at least one of the atomizer units and the rotary feedthrough. The atomizer pressure regulator is preferably designed to be electrically controllable.

By means of the atomizer pressure regulator, it is possible, analogously to the statements for the pump pressure regulator, to regulate an inlet pressure applied to the atomizer pressure regulator to an adjustable outlet pressure. The inlet pressure can preferably be reduced or increased using a pressure booster. Investigations by the applicant have shown that an outlet pressure of between 2 and 4 bar should preferably be set for the atomizer pressure regulator in order to achieve an optimal coating result.

The atomizer pressure regulator is preferably connected to a plurality of atomizer units, preferably to all atomizer units of the rotary unit. The advantage here is that only one atomizer pressure regulator is required to regulate the atomizer pressures of several atomizer units. If the atomizer pressure regulator is connected to a plurality of atomizer units, an arrangement of several pneumatic branching elements can be arranged between the atomizer pressure regulator and the atomizer units. As a result, the compressed air flow output by the atomizer pressure regulator can be divided between the plurality of atomizer units, preferably all atomizer units. It is within the scope of the advantageous development that the atomizer pressure regulator can be controlled mechanically or pneumatically.

Preferably, the atomizer pressure regulator is designed to be electrically controllable. The control unit is connected to the signal line of the rotary union or connected to the atomizer pressure regulator by means of the wireless transmitter-receiver arrangement. The required output pressure for an optimal coating result can be set using a control signal from the control unit. It is also within the scope of the advantageous development that the atomizer pressure regulator can include a sensor for measuring and monitoring the atomization pressure and communicates the output pressure to the control unit during operation of the coating device. It is within the scope of the advantageous development that the valve device is located in the signal path between the rotary feedthrough and the atomizer pressure regulator.

The electrical energy required to operate the electrically controllable atomizer pressure regulator can be provided in a simple manner via the rotary union. Preferably, the electrical energy for the atomizer pressure regulator can also be provided via the valve device if it is connected to the rotary union in terms of energy. Alternatively, the electrical energy required can be provided via the compressed air-operated generator.

In an advantageous development, at least one of the spray units has at least one compressed air-operated shaping air unit for adjusting a jet shape of the coating agent emitted from the spray unit, wherein the shaping air unit is connected to the compressed air source at least via the rotary feedthrough.

The jet shape of the coating agent emitted from the spray unit is an important factor influencing the achievable coating quality. The shaping air unit is used to influence the jet shape of the coating agent. For this purpose, the shaping air unit has a mechanically adjustable air cap on which one or more air nozzles are located. By mechanically adjusting the air cap, the compressed air flow can be changed as required in order to adjust the jet shape of the coating agent accordingly.

It is within the scope of the advantageous development that the rotary feedthrough is pneumatically connected to the shaping air unit via the valve device. Alternatively, the shaping air unit is preferably connected to the rotary feedthrough via the pneumatic branching element already mentioned above or another pneumatic branching element. In this case, the shaping air unit is supplied with compressed air independently of the pneumatic valve device. The pneumatic branching element can comprise a T-piece or a comparable pneumatic component in the manner already explained in order to divide the compressed air flow, which is provided for the rotary unit by means of the rotary feedthrough, at least between the valve device and the shaping air unit.

In an advantageous further development, a shaping air pressure regulator is arranged between the shaping air unit and the rotary feedthrough, which is preferably designed to be electrically controllable.

Using the mold air pressure regulator, the mold air pressure can be regulated from an increased input pressure to an adjustable output pressure and reduced or increased as required. The pressure level of the mold air pressure is preferably between 2 and 4 bar, so that the output pressure of the mold air pressure regulator can be adjusted accordingly to achieve an optimal coating result. The output pressure of the mold air pressure regulator can be controlled manually or pneumatically, analogous to the statements regarding the pressure regulators already described.

Preferably, the mold air pressure regulator is designed to be electrically controllable. The control unit is connected to the mold air pressure regulator via the signal line of the rotary union or by means of the wireless transmitter-receiver unit. This allows the required output pressure for an optimal coating result to be set using a control signal from the control unit. It is within the scope of the advantageous development that the The mold air pressure regulator can include a sensor for measuring and monitoring the mold air pressure and communicates the output pressure to the control unit during operation of the coating device. It is within the scope of the advantageous development that the valve device is located in the signal path between the rotary union and the mold air pressure regulator.

Depending on whether the shaping air unit is connected to the rotary feedthrough via the valve device or via the branching element, the shaping air pressure regulator can be arranged between the shaping air unit and the valve device or between the shaping air unit and the branching element. The shaping air pressure regulator is preferably connected to a plurality of shaping air units, preferably to all shaping air units, on the rotary unit. The advantage here is that only one shaping air pressure regulator is required to regulate the shaping air pressures of several shaping air units.

Any electrical energy required to operate the electrically controllable molded air pressure regulator can be provided in a simple manner via the rotary union. Preferably, the electrical energy for the molded air pressure regulator can also be provided via the valve device if it is connected to the rotary union for energy purposes. Alternatively, any electrical energy required can be provided via the compressed air-operated generator.

In an advantageous development, the rotation unit comprises a plurality of adjusting means, on each of which at least one of the spray units is arranged. The adjusting means are designed to adjust a position, preferably an orientation, of the at least one spray unit arranged on them in relation to the workpiece holder.

According to the above-described development, the adjusting means serve to adjust the position and preferably the orientation of the spray units relative to the workpiece in such a way that the workpiece can be evenly coated. This is advantageous because the positions of the spray units, each of which has a Position and orientation, relative to the workpiece holder and the workpiece arranged thereon due to the rotational movement of the rotary unit. Preferably, the adjusting means serves only to adjust the orientation, i.e. the relative angular position of at least one spray unit relative to the workpiece.

Preferably, the adjusting means are designed to be controlled depending on a rotational position of the rotary unit relative to the machine frame. In particular, a mechanical control is conceivable here. For this purpose, the adjusting means can be coupled to a curved path arranged on the machine frame, for example by means of a rod or any other force transmission element. The curved path is preferably formed by a groove or edge running around the rotation axis of the rotary unit. The course of the curved path preferably corresponds approximately to an oval or preferably to a Cassini curve, the shape of which essentially corresponds to that of an oval pressed in on two sides. When the rotary unit rotates, the rod slides along the curved path at the end and exerts forces on the adjusting means in accordance with the course of the curved path. These forces in turn cause an adjustment of the spray unit connected to the adjusting means.

In an advantageous further development, the actuating means comprises an electric drive and is designed to be electrically controllable.

The development described above makes it possible to electrically adjust the spray unit or several spray units connected to the actuating means. Preferably, the actuating means are each a servo drive with which the position, in particular the orientation of the spray unit, can be adjusted in a path- and/or angle-controlled manner. The electrical drive of the actuating means is preferably connected to the control unit via the rotary feedthrough, with the electrically controllable valve device preferably being located in the signal path between the rotary feedthrough and the actuating means. Alternatively, the actuating means can be controlled via the wireless transmitter-receiver arrangement. connected to the control unit by means of signals. The electrical energy required for the electrical drive can preferably be provided via the rotary union and preferably via the valve device. Alternatively, the electrical energy required can be provided via the compressed air-operated generator.

The advantage of an electrically controlled adjustment of the spray unit is that it can be flexibly adjusted and is not susceptible to malfunctions during operation. In particular, it is easy to adapt the orientation of the spray units to workpieces with different geometries and dimensions.

In an advantageous development, the workpiece holder is designed as a conveyor belt in order to convey the workpiece from an inlet area of the machine frame to an outlet area by means of a linear movement. The workpiece is thereby swept over in the inlet area and in the outlet area by one of the spray units during a rotational movement of the rotation unit. The workpiece is preferably swept over along at least two intersecting movement paths, so that an intersecting spray pattern is produced on the workpiece.

According to the development described above, the workpiece is arranged on the conveyor belt in front of the inlet area and is conveyed by the conveyor belt into the outlet area and beyond. The conveying movement preferably takes place at an adjustable and preferably constant speed.

In the inlet area, the workpiece is covered by at least one spray unit of the rotary unit. The superimposed rotational movement of the rotary unit and the linear movement of the workpiece result in a sickle-shaped path for the movement path of the spray unit in the inlet area. In the outlet area, the workpiece is then sprayed by the same spray unit or one of the other spray units of the rotary unit. This also results in a crescent-shaped path which overlaps the crescent-shaped path applied in the inlet area.

The process described above is preferably repeated several times, with the crescent-shaped paths in the inlet area and in the outlet area preferably being applied to the workpiece offset from one another in order to coat the entire surface. The intersecting, crescent-shaped paths along which the coating agent is applied to the workpiece lead to a homogeneous distribution of the coating agent, which appears particularly uniform to the human eye.

In an advantageous development, the rotary joint has a coating agent channel and a flushing agent channel, which are separated from one another by at least one seal, wherein the coating agent channel is designed to connect the coating agent source to the pump in a fluid-conducting manner and wherein the flushing agent channel is designed to absorb a leakage flow which may emerge at the seal and which contains coating agent from the coating agent channel.

As already explained above, the swivel joint serves to provide a fluid-conducting connection between the coating agent source of the machine frame and the pump of the rotary unit. This fluid-conducting connection is formed by the coating agent channel, which is formed partly by the fixed swivel joint part and partly by the rotatable swivel joint part. Between the swivel joint parts, the coating agent channel has a transition area in which the coating agent passes from the fixed swivel joint part into the rotatable swivel joint part. In this area, the swivel joint parts are separated from one another, which enables them to rotate relative to one another. However, this separation between the swivel joint parts is accompanied by the formation of at least one gap or channel between them. Such a gap or channel is usually sealed by means of the seal already mentioned above in order to prevent uncontrolled escape of coating agent from the swivel joint. However, it cannot be permanently and completely ruled out that coating agent will leak past the seal from the coating agent channel.

The flushing agent channel is formed in the swivel joint so that the leakage flow does not dry between the swivel joint parts behind the seal and possibly stick them together. This is arranged in relation to the flow direction of the leakage flow in such a way that the leakage flow can pass the seal into the flushing agent channel and be flushed away by a flushing agent located therein. Since the pressure in the flushing agent channel is usually lower than in the coating agent channel, it can be sealed off from the environment more easily. In addition, the sealing of the flushing agent channel is simplified because the flushing agent contains fewer corrosive or abrasive components than the coating agent.

It is within the scope of the advantageous development that the swivel joint can have a plurality of coating agent channels, via which a plurality of pumps are each connected to a coating agent source. It is also within the scope of the advantageous development that the swivel joint can have a plurality of flushing agent channels. In this case, the flushing agent channels and the coating agent channels are separated from one another in pairs by a seal, whereby a leakage flow that inevitably escapes at the seal can be flushed away through the respective flushing agent channel. It is also within the scope of the advantageous development that two coating agent channels are assigned to a common flushing agent channel and are separated from it by means of a leaky seal. In this case, the flushing agent channel serves to simultaneously flush away several leakage flows of different coating agents.

In an advantageous further development, the detergent channel is connected to a detergent source via a detergent inlet on the swivel joint. Furthermore, the Detergent channel connected to a detergent sink via a detergent outlet on the swivel joint.

According to the above-described development, the detergent source preferably comprises a detergent tank and a detergent pump. The detergent pump serves to convey detergent from the detergent tank into the detergent channel and to circulate it at least in the swivel joint at a preferably adjustable pressure before it is drained to the detergent sink via the detergent outlet. The detergent sink is preferably formed at least partially by the same detergent tank to which the detergent pump is connected. It is also within the scope of the advantageous development that a second detergent tank is provided for the detergent sink, into which a non-reusable and contaminated detergent can be drained from the detergent outlet.

In an advantageous development, a temperature sensor is arranged on or in the swivel joint.

When operating coating devices, it is usual for the coating agent or the rinsing agent to be flammable. In particular, an explosive coating agent-air mixture can arise when the coating agent is sprayed. For safety reasons, it is therefore desirable to ensure that those components which are directly or indirectly connected in a heat-conducting manner to the flammable coating agent and/or rinsing agent and/or coating agent-air gas mixture are operated in a temperature range which is below the respective ignition temperature. Since the swivel joint serves both to conduct coating agent and preferably rinsing agent, safety in the operation of the coating device is increased if the temperature in the area of the swivel joint or the temperature of the swivel joint is measured. In particular, it is advantageous if the temperature sensor is arranged in the area of the coating agent channel and/or in the area of the rinsing agent channel in order to measure the temperature. to be able to detect directly in the areas where there is a risk of inflammation. It is also part of the advantageous development that the temperature sensor is arranged in the area of the seals of the swivel joint, since more heat is generated in this area during operation of the swivel joint than in the rest of the structure of the swivel joint.

In addition to fire and/or explosion protection, the temperature at or in the swivel joint is also relevant because it influences the viscosity of the coating agent. Measuring the temperature therefore allows at least some conclusions to be drawn about the quality of the coated workpieces. In addition, the quality of the coated workpieces can be positively influenced by appropriate temperature control of the swivel joint depending on the measured temperature.

During operation of the coating device, the temperature sensor transmits the recorded temperatures to the control unit, preferably via the valve device and the rotary feedthrough. The temperature signal can be present as an analog signal and can be converted into a digital signal by means of the valve device. A field bus connection can be used to transmit the signal converted in this way to the control unit via the rotary joint, so that it can be used to control the coating device. In particular, it is within the scope of the advantageous development that the pumping power of a rinsing agent pump for conveying the rinsing agent in the rinsing agent channel is adjusted depending on the temperature signal, so that the conveyed rinsing agent can also serve as a coolant. Alternatively, the recorded temperature can be transmitted via the wireless transmitter-receiver arrangement.

In an advantageous development, the rotation unit has a base body in which at least the pump and the valve device are arranged. Furthermore, the rotation unit has a plurality of support arms on which at least one of the spray units, preferably two spray units, are arranged. Preferably, the support arms protrude in relation to on the rotation axis of the rotation unit radially from the base body.

The base body can be formed from a frame, which gives the rotation unit its stability and rigidity. In addition, the base body can have one or more flat cladding elements with which the interior of the base body is sealed off from view and against dirt. Preferably, the axis of rotation of the rotation unit runs through the base body, with heavy components of the rotation unit in particular being arranged in the base body.

The support arm is preferably designed in a lightweight manner, for example as a hollow profile or with a lattice structure. Overall, this allows the largest proportion of the weight of the rotation unit to be concentrated in the area of the rotation axis of the rotation unit. This has a beneficial effect on the dimensioning of the drives required to generate the rotational movement. This is because the weight concentration described above means that less drive power is required to accelerate the rotation unit compared to an even weight distribution on the rotation unit. The base body can also be used to accommodate bearings for the movable mounting of the rotation unit relative to the machine frame. The mounting of the rotation unit relative to the machine frame is advantageously designed in such a way that the height of the rotation unit is adjustable. This is advantageous because it also allows the height of the spray units to be adjusted, so that workpieces of different thicknesses in particular can be coated from a uniform distance.

In an advantageous further development, the rotary joint and the rotary feedthrough are arranged coaxially to one another along the rotation axis of the rotation unit, with the rotary feedthrough being located above the rotary joint.

By arranging the swivel joint below the rotary union, the coating agent only needs to be pumped to a minimum required level in the lower area of the rotary unit so that it can be made available to the pump arranged on it.

In an advantageous development, the coating agent source comprises a low-pressure pump and a coating agent tank, wherein the low-pressure pump is arranged in a fluid-conducting manner between the rotary joint and the coating agent tank.

The development described above is based on the knowledge that the reliability of the coating agent supply during operation can be increased if a low-pressure pump is provided in addition to the pump of the rotary unit. The pump of the rotary unit can, if dimensioned accordingly, also be suitable on its own to suck in the coating agent through the rotary joint. However, studies have shown that the pump of the rotary device can be dimensioned significantly smaller if the low-pressure pump is also provided. The smaller dimensioning of the pump arranged on the rotary unit is accompanied by a correspondingly smaller required installation space and weight for the rotary unit. Using the additional low-pressure pump, a differential pressure can be set between the coating agent channel and the flushing agent channel of the rotary joint if required in order to generate a pressure gradient between the coating agent channel and the flushing agent channel. The flushing agent pump can be set to a pressure of 1.5 bar and the low-pressure pump to a pressure of 2.0 bar, for example. The flushing agent pump and the low-pressure pump are preferably structurally identical double diaphragm pumps.

Further preferred features and embodiments of the coating device according to the invention are explained below using two embodiments and the drawings. The embodiments are merely advantageous embodiments of the invention and therefore do not restrict it.

Figur 1

ein erstes Ausführungsbeispiel einer erfindungsgemäß ausgestalteten Beschichtungsvorrichtung in schematischer Darstellung;

Figur 2

ein zweites Ausführungsbeispiel einer erfindungsgemäß ausgestalteten Beschichtungsvorrichtung in schematischer Darstellung.

Show it:

Figure 1

a first embodiment of a coating device designed according to the invention in a schematic representation;

Figure 2

a second embodiment of a coating device designed according to the invention in a schematic representation.

In the Figure 1 The coating device 1 shown comprises a machine frame 2 with a workpiece holder 3 on which a workpiece 4 to be coated is arranged. In the example shown, the workpiece 4 is a flat wooden part which is to be evenly painted on the surface and on the side edges.

Furthermore, a compressed air source 5, an electrical control unit 6 and an electrical voltage source 7 are arranged on the machine frame 2. In the illustration shown, the compressed air lines leading from the compressed air source 5 and their branches are shown as solid connecting lines. The electrical control lines leading from the control unit 6 are shown as single dashed connecting lines. The power lines leading from the electrical voltage source 7 are shown as dashed connecting lines.

A coating agent tank 8, a low-pressure pump 9, a rinsing agent tank 10 and a rinsing agent pump 11 are also arranged on the machine frame 2.

The coating device 1 further comprises a rotation unit 12, which can be rotated relative to the machine frame 2 and is connected to the components of the fixed machine frame 2 via a rotary joint 13 and a rotary feedthrough 14. This will be discussed in more detail below.

The rotation unit 12 comprises a base body 15 and a plurality of support arms protruding from the base body 15, of which only one support arm is provided with the reference number 16.

The base body 15 comprises a frame (not shown here) which forms an interior in which a compressed air-operated high-pressure pump 17 and a valve device 18 are arranged. The high-pressure pump 17 is designed as a double diaphragm pump. In another embodiment, the high-pressure pump 17 can also be designed as a piston pump. The valve device 18 is designed as an electrically controllable valve island.

A spray unit 20 is arranged on each of the support arms 16, each of which comprises a compressed air-controlled valve 21 for controlling the coating agent output. Furthermore, the spray units 20 each comprise an atomizer unit 22 and a shaping air unit 23.

Furthermore, an adjusting means 24 is arranged on each of the support arms 16, which is mechanically coupled to a curved path in a manner not shown here and by means of which the pivoting position of a respective spray unit 20 relative to the workpiece holder 3 and the workpiece 4 located thereon can be adjusted.

In a manner not shown here, the coating device 1 comprises a drive with which the rotation unit 12 can be set in a rotational movement relative to the machine frame 2, in particular relative to the workpiece holder 3 and the workpiece 4 located thereon. In this case, coating agent is dispensed from the spray units 20 over the surface of the workpiece 4.

The swivel joint 13 serves in the present case to supply the rotation unit 12, which can be rotated relative to the machine frame 2, and the spray units 20 arranged on the rotation unit 12 with coating agent. the coating agent is conveyed by means of the low-pressure pump 9 via connection II into the rotary joint 13 and thereby reaches a coating agent channel (not shown) of the rotary joint 13. In the example shown, the rotary joint 13 comprises two parts which are connected to one another in a sealing manner and which can be rotated relative to one another. A fixed part of the rotary joint is connected to the machine frame 2 and the other, movable part is connected to the rotation unit 12.

This design of the swivel joint 13 leads to an unavoidable leakage flow between the fixed and the moving part of the swivel joint 13. Although there is a seal in this area, it cannot be permanently and completely ruled out that coating agent will leak past the seal and out of the coating agent channel. To ensure that the leakage flow does not dry between the swivel joint parts behind the seal in relation to its flow direction and possibly stick them together, a flushing agent channel is formed in the swivel joint. This is arranged in relation to the flow direction of the leakage flow in such a way that the leakage flow can pass past the seal into the flushing agent channel and be flushed away by a flushing agent that is temporarily or permanently conveyed therein.

The rinsing agent channel extends from connection I to connection III of the swivel joint 13. Connection I is connected to the rinsing agent tank 10 via the rinsing agent pump 11 and serves to supply the rinsing agent into the swivel joint 13. Connection III represents a drain opening through which the rinsing agent mixed with the removed leakage flow returns to the rinsing agent tank 10.

The coating agent channel is connected on the outlet side to the suction side of the high-pressure pump 17. The coating agent is fed through the high-pressure pump 17 to the spray units 20 via distribution lines 19.

The high-pressure pump 17 is operated by compressed air and moves with the rotation unit 12. To ensure a simple compressed air supply to the high-pressure pump 17 In order to enable this, the rotary union 14 serves to provide compressed air from the compressed air source 5 for the rotation unit 12 which can be rotated relative to the machine frame 2.

A special feature of the coating device 1 shown is that the valve device 18 is arranged in the base body 15 of the rotary unit 12 and is designed to controllably distribute the compressed air provided by the rotary feedthrough 14 to the rotary unit. For this purpose, the valve device 18 is designed as a valve island and has a distributor bar on which a plurality of pneumatic valves in the form of valve disks (not shown) are arranged. The valve disks can each be selectively locked and unlocked by an electrical control signal. The required control signal is provided by the control unit 6 and is also output to the valve device 18 via a signal line of the rotary feedthrough 14. In addition, the rotary feedthrough 14 has a power line for power transmission, by means of which the valve device 18 is also supplied with electrical energy from the voltage source 7. On the exhaust air side, the valve device 18 is connected to the valves 21 via a plurality of exhaust air connections.

In the exemplary embodiment shown here, the valve device 18 serves to control the valves 21. For this purpose, the valve device 18 can have comparatively small flow cross-sections and can therefore be constructed compactly. The high-pressure pump 17, on the other hand, requires a volume flow for its operation which cannot be provided by the valve device 18. Instead, the high-pressure pump 17 is connected to the rotary feedthrough 14 via a pneumatic branching element 30. In the exemplary embodiment shown, the coating device comprises a total of three branching elements which are designed as T-pieces and serve to divide a compressed air flow provided by the rotary feedthrough 14 independently of the valve device 18 on the rotary unit 12.

As in Figure 1 shown, the compressed air flow is guided to the high-pressure pump 17 by means of the branching element 30 via a pump pressure regulator 25. The pump pressure regulator 25 serves to regulate the drive pressure of the high-pressure pump 17 to a desired pressure level. In a corresponding manner, a pressure regulator 26 or 27 is arranged between the rotary feedthrough 14 and the atomizer units 22 and between the rotary feedthrough 14 and the shaping air units 23. The pressure levels can be digitally adjusted by the control unit 6. The pressure regulators 25, 26, 27 are connected to the electrical voltage source 7 in terms of energy via a current-conducting connection in the rotary feedthrough 14. A coating agent pressure regulator 29 is arranged in a corresponding manner between the high-pressure pump 17 and a spray unit 20 in each case. For better clarity, the energy and signaling connection of the coating agent pressure regulators 29 is not shown.

To monitor the temperature of the rotary joint 13, a temperature sensor 28 is arranged in the area of the coating agent channel of the rotary joint 13, which is connected in terms of energy and signaling to the electrical voltage source 7 or to the control unit 6 via the valve device 18 and the rotary joint 14. Alternatively, the temperature sensor 28 can be designed as a temperature-dependent resistor.

In the Figure 2 The coating device 1' shown corresponds in its construction essentially to the coating device 1 according to Figure 1 . In contrast to the Figure 1 In the coating device 1 shown, the coating agent device 1 ` has a valve device 18 which serves as a central distribution element for compressed air, signals and electrical energy on the rotation unit 12.

For this purpose, the rotary union 14 must be installed as described Figure 1 constructed and connected pneumatically, signalling-technically and energy-technically to the valve device 18.

A compressed air flow directed to the rotation unit 12 enters the valve device 18 and can be distributed to the pneumatically controlled and/or driven components on the rotation unit 12 depending on the control signals from the control unit 6. Furthermore, the valve device 18 is designed to output control signals from the control unit 6 directly or in converted form to other electrically controlled components. In the embodiment shown, the valve device 18 outputs electrical control signals to the pressure regulators 25, 26, 27 and 29.

In addition, the valve device 18 is designed with suitable signal inputs to receive the temperatures measured by means of the temperature sensor 28 and to output them to the control unit 6. The coating device 1' also has electrically controllable actuating means 24, which are connected to the valve device 18 by means of signals.

Furthermore, the valve device 18 has electrical connections in order to provide electrical energy for the electrically operated components on the rotation unit 12. For this purpose, the valve device is connected in terms of energy to the pressure regulators 25, 26, 27, 29, the temperature sensor 28 and the electrically controllable actuating means 24.

Another difference between the coating device 1' according to Figure 2 and the coating device 1 according to Figure 1 consists in that the coating device 1' has a pressure regulator 26 for each of the atomizer units 22 and a pressure regulator 27 for each of the shaping air units 23.

Claims (15)

1. Coating device (1, 1') for applying a coating agent to the surface of a workpiece (4), the coating device comprising a machine frame (2) having a workpiece mount (3), a coating agent source and a compressed air source (5), further comprising a rotary unit (12) which is rotatable in relation to the machine frame (2) and has at least one pump (17) and a plurality of spray units (20), wherein the at least one pump (17) on a suction side is connected to the coating agent source by a fluid-conducting rotary joint (13), and on a pressure side is connected to the spray units (20),
   characterized in that,
   the rotary unit (12) has a pneumatic valve device (18), and the spray units (20) each have a compressed air controlled valve (21) for controlling the delivery of coating agent, wherein the valve device (18) on an intake air side is connected to the compressed air source (5) at least via a fluid-conducting rotary feedthrough (14), and on an exhaust air side is connected to the compressed air controlled valves (21) of the spray units (20).
2. Coating device according to claim 1,
   in which the pump (17) is configured to be operated by compressed air and is connected to the compressed air source (5) at least via the rotary feedthrough (14).
3. Coating device according to claim 1 or 2,
   in which the pneumatic valve device (18) can be controlled electrically, the rotary feedthrough (14) has at least one signal line, and the machine frame (2) comprises an electric control unit (6), which for transmitting signals is connected at least to the valve device (18) by the rotary feedthrough (14).
4. Coating device according to any one of claims 1 to 3,
   in which the rotary feedthrough (14) is configured for transmitting electric power, and the machine frame (2) comprises an electric voltage source (7), which for transmitting power is connected at least to the valve device (18) by the rotary feedthrough (14).
5. Coating device according to claim 1 or 2,
   in which the pneumatic valve device (18) is electrically controllable, and the machine frame (2) comprises an electric control unit (6), wherein at least the valve device (18) and the control unit (6) are connected by a wireless transceiver for signal transmission, and wherein preferably a pneumatically operated generator is arranged on the rotary unit (12), said pneumatically operated generator at least being connected to the compressed air source (5) via the rotary feedthrough (14) and being configured to supply at least the valve device (18) with electric power.
6. Coating device at least according to claim 2,
   in which the pump (17) on the suction side is connected to the rotary feedthrough (14) by a pump pressure regulator (25), wherein the pump pressure regulator (25) is preferably electrically controllable.
7. Coating device according to any one of the preceding claims,
   in which a coating agent pressure regulator (29) is arranged between the pump (17) and at least one spray unit (20), wherein the coating agent pressure regulator (29) is preferably electrically controllable.
8. Coating device according to any one of the preceding claims,
   in which at least one of the spray units (20) has at least one compressed air operated atomizer unit (22) for atomizing the coating agent, wherein the atomizer unit (22) is connected to the compressed air source (5) at least via the rotary feedthrough (14), and wherein preferably an atomizer pressure regulator (26) is arranged between the atomizer unit (22) and the rotary feedthrough (18), which an atomizer pressure regulator (26) is preferably configured to be electrically controllable.
9. Coating device according to any one of the preceding claims,
   in which at least one of the spray units (20) has at least one compressed air operated air-forming unit (23) that adjusts a jet shape of the coating agent delivered from the spray unit (20), wherein the air-forming unit (23) is connected to the compressed air source (5) at least via the rotary feedthrough (14) and wherein preferably an air-forming pressure regulator (27) is arranged between the air-forming unit (23) and the rotary feedthrough (14), which air-forming pressure regulator (27) is preferably electrically controllable.
10. Coating device according to any one of the preceding claims,
    in which the rotary unit (12) comprises a plurality of actuators (24) on each of which one of the spray units (20) is arranged, wherein the actuators (24) are configured to adjust a position of the respective spray unit (20) arranged thereon in relation to the workpiece mount (3), in particular an orientation of the respective spray unit (20), and the actuators (24) comprise in each case at least one electric drive and are preferably electrically controllable.
11. Coating device according to any one of the preceding claims,
    in which the workpiece mount (3) is in the form of a conveyor belt to convey a workpiece (4) via a linear movement from an inlet region of the machine frame (2) to an outlet region, wherein the spray units (24) are configured to move in a rotating movement of the rotary unit (12) sweeping across the workpiece (4) conveyed by the conveyor belt in the inlet region and in the outlet region.
12. Coating device according to any one of the preceding claims,
    in which the rotary joint (13) has a coating agent channel and a rinsing agent channel which are isolated from one another by at least one seal, wherein the coating agent channel is configured to fluidically connect the coating agent source to the pump (17), wherein the rinsing agent channel is configured to receive a leakage flow which exits at the seal and contains coating agent from the coating agent channel, wherein the rinsing agent channel is preferably connected to a rinsing agent source by a rinsing agent infeed on the rotary joint (13), and the rinsing agent channel is connected to a rinsing agent sink by a rinsing agent outlet on the rotary joint.
13. Coating device according to any one of the preceding claims,
    in which at least one temperature sensor (28) is arranged in or on the rotary joint (13).
14. Coating device according to any one of the preceding claims,
    in which the rotary unit (12) has a main body (15) in which at least the pump (17) and the valve device (18) are arranged, and in which the rotary unit (12) further includes a plurality of support arms (16) on each of which at least one of the spray units (20) is arranged, preferably two spray units (20), wherein preferably the rotary joint (13) and the rotary feedthrough (14) are arranged so as to be mutually coaxial along a rotational axis of the rotary unit (12), and the rotary feedthrough (14) is situated above the rotary joint (13).
15. Coating device according to any one of the preceding claims,
    wherein the coating agent source comprises a low-pressure pump (9) and a coating agent tank (8), wherein the low-pressure pump (9) is fluidically arranged between the rotary joint (13) and the coating agent tank (8).

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