HK1112027A - Electrodeposition coating installation - Google Patents

Description

Electrophoretic painting equipment

Technical Field

The invention relates to an electrocoating system for painting workpieces, in particular vehicle bodies, comprising at least one immersion bath in which at least one electrode is arranged, a transport device for transporting the workpieces into the immersion bath and out of the immersion bath, and a power supply device which generates an output voltage, in particular a DC output voltage, from an AC input voltage, one output potential of which is applied to at least one workpiece to be painted and the other output potential of which is applied to at least one electrode arranged in the immersion bath.

Background

Such an electrocoating installation is known, for example, from DE10325656B 3.

The disclosed power supply device of such an electrocoating installation comprises a plurality of power supply units, one pole of which can be selectively connected to one of a plurality of electrode groups and the other pole of which can be connected to one of a plurality of contact rails arranged one behind the other in the transport direction of the transport device. During the passage through the bath, the workpieces are each in electrically conductive contact with one of the contact rails, so that the workpieces are at the potential assigned to this contact rail. If the workpiece approaches the transition between two successive contact tracks, these are electrically conductively connected by means of a coupling thyristor.

By dividing the workpiece into a plurality of contact rails arranged one after the other in the transport direction, different output potentials can be applied to the workpieces which pass through the dipping bath continuously, in such an arrangement, as long as the contact rails are each shorter than the distance between two workpieces arranged one after the other. But the workpieces cannot therefore be arranged one after the other at any small distance.

Disclosure of Invention

The object of the invention is to provide an electrocoating installation of the type mentioned at the outset which makes it possible to apply individual output potentials to each workpiece in a simple manner.

This object is achieved according to the invention in an electrocoating installation having the features of the preamble of claim 1 in that the power supply device comprises at least one current control unit which, together with the workpieces assigned to the current control unit, is moved through at least one section of the electrocoating installation and supplies the workpieces assigned to the current control unit with an output potential.

The solution according to the invention is based on the idea of, instead of the fixed current control units used in conventional electrocoating plants, which supply constant output potentials along the contact rails to the contact rails, assigning a respective moving current control unit to each workpiece passing through the dip bath, which unit moves together with the assigned workpiece and supplies the respective assigned workpiece with the respective required output potential individually.

The need for the division of the contact rails at the workpiece clock intervals is therefore eliminated in the electrocoating installation according to the invention, and the workpieces can in principle be moved through the bath in any desired density sequence.

In principle, either a cathode or an anode of an output voltage can be applied to the workpiece.

Preferably a cathode for applying an output voltage to the workpiece.

In a preferred embodiment of the invention, the transport device comprises a plurality of holders, on each of which a workpiece to be painted is arranged, and a current control unit is assigned to each holder, which supplies the workpiece arranged on the associated holder with an output potential.

In particular, a current control unit can be provided on each holder, which unit supplies an output potential to the workpiece arranged on the respective holder.

In order to make it possible to supply output potentials to a plurality of workpieces which pass through the dip bath in sequence, it is preferable that the electrodeposition coating facility includes a plurality of current control units and that the output potential supplied by each of the current control units is independent of the output potentials supplied by the other current control units.

In order to optimize the coating distribution of each workpiece in the bath in a type-specific manner with respect to the workpiece type, each current control unit controls or regulates the output voltage and/or the output current for the assigned workpiece in accordance with a type-specific predefined voltage or current distribution with respect to the workpiece type. In this way, different types of workpieces passing through the immersion bath in any order can each be painted in a type-specific optimized manner.

In a preferred embodiment of the invention, the power supply device comprises at least one contact rail to which at least one current control unit can be connected.

In this case, the power supply device preferably comprises a rectifier circuit which generates an intermediate output voltage from the ac input voltage and applies a potential thereof to a contact rail to which at least one current control unit can be connected.

In this case, a further potential of the intermediate output voltage is also applied to the at least one electrode in the at least one immersion bath.

In addition, the other potential of the intermediate output voltage is applied to a second contact rail, which is preferably arranged substantially parallel to the first contact rail to which the intermediate output voltage is applied.

The rectifier circuit may comprise a preferably uncontrolled diode rectifier bridge.

In addition, the rectifier circuit includes a filter circuit for reducing the residual ripple of the intermediate output voltage.

It is advantageous if the electrocoating installation of the at least one dip bath has only one first contact rail to which the intermediate output voltage is applied at one potential and only one second contact rail to which the intermediate output voltage is applied at another potential, wherein the at least one current control unit can be connected to the first and second contact rails.

The presence of only a single first and a single second contact rail per dipping basin simplifies the construction and installation of the power supply device. Furthermore, all the problems associated with the transition of a workpiece from one contact rail to its subsequent contact rail in the transport direction are eliminated. The coupling thyristors required for the electrically conductive connection of two successive contact rails of a conventional electrocoating installation when the workpiece is changed from one contact rail to the other can be eliminated. Furthermore, no sensors are required to detect the approach of the workpiece to the transition between two successive contact rails.

It is also advantageous if at least one contact rail is assigned to at least one immersion bath of the electrocoating installation, to which at least one current control unit can be connected and which extends without transition beyond the length of the immersion bath.

In a preferred embodiment of the invention, the current control unit, which is moved together with the workpieces by a section of the electrocoating installation and supplies the workpieces assigned to the current control unit with an output potential, comprises a switching element which converts a switching element input voltage supplied to the switching element into a switching element output voltage which oscillates at a certain clock frequency.

Such a switching element may comprise in particular at least one field effect Transistor and/or at least one IGBT (insulated Gate Bipolar Transistor).

The switching element can be oscillated at a very high clock frequency by means of such fast-switching transistors, as a result of which the electronic components required for the current control unit can be designed with small dimensions, so that the moving current control unit has only a low weight and a small volume.

In order to be able to supply the respectively required output potential to the workpieces assigned to the current control unit in a simple manner, the clocked switching element output voltage can have a controllable duty cycle.

In order to be able to achieve any predefinable distribution of the output potential of the workpiece, the current control unit can have a regulating circuit which controls the switching element as a function of the rated output voltage.

The clock frequency at which the switching element output voltage oscillates is advantageously at least about 10kHz, preferably at least about 20 kHz.

To avoid electromagnetic radiation effects, it is advantageous if the pulse repetition frequency is at most about 200kHz, preferably at most about 100 kHz.

To reduce the residual ripple of the output potential of the current control unit, the current control unit may comprise a filter circuit.

In a special embodiment of the invention, the current control unit comprises a pulse-forming circuit. An output potential that pulses at a repetition rate of, for example, about 1kHz to about 10kHz, may be applied to the workpiece.

This can lead to a better painting effect, in particular in the case of painting hollow bodies.

Claim 20 relates to a holder for an electrocoating installation according to the invention, in which the holder has a current control unit which supplies an output potential to workpieces arranged on the holder.

Drawings

Further features and advantages of the invention are the subject of the following description and the drawings of the embodiments. In the drawings:

fig. 1 shows a schematic diagram of a power supply unit and a current control unit moving together with a workpiece of an electrocoating installation;

FIG. 2 shows a schematic block diagram of a current control unit;

FIG. 3 shows a schematic side view of a motor vehicle body which is arranged on a mounting of the electrocoating installation and on the upper side of the bath level;

FIG. 4 shows a schematic top view of the holder of FIG. 3 from above;

FIG. 5 shows a schematic cross-sectional view of an electrocoating plant with automotive bodies arranged above an immersion bath;

FIG. 6 shows a schematic side view of a motor vehicle body arranged on a mounting frame of the electrocoating installation and below the bath level; and

fig. 7 shows a schematic section through an electrocoating plant with a motor vehicle body completely immersed in the bath.

Identical or functionally identical components are denoted by the same reference symbols in all the figures.

Detailed Description

The electrocoating plant for painting motor vehicle bodies 102, which is shown in fig. 1 to 7 and designated as a whole by 100, comprises at least one dip bath 104, which is filled with a paint liquid from a dip bath 108 to a liquid level 106.

Furthermore, the electrocoating installation 100 comprises a conveyor device 110, by means of which the vehicle body 102 can be completely immersed in the dipping bath 108, can be moved in the completely immersed state in a horizontal translation direction 112 through the dipping bath 108 and can then be transported out of the dipping bath 108.

The transport device 110 comprises a guide device 114 having two guide rails 116a, 116b, one of which extends parallel to the direction of translation 112 on the left or right side of the immersion bath 108.

As best seen in fig. 5, two guide rails 116a, 116b are disposed above the liquid surface 106 of the immersion bath 108.

Furthermore, the conveying device 110 comprises a plurality of holders 118 (only one of which is shown in each case in fig. 3 to 7) which are individually movable and independently of one another along the guide 114 of the conveying device 110 and follow one another at a distance along the guide 114.

Each holder 118, as can best be seen from fig. 4, comprises a base frame 120 guided on the guide 114, which has substantially the shape of a rectangular frame.

At its rear end (as viewed in the direction of translation 112), the base frame 120 has two drive rollers 122 which roll on the horizontal upper side of the respectively associated guide rail 116a, 116 b.

One of the two driven rollers 122 is directly set into rotational motion by means of a translatory drive motor 124, which is arranged on the base frame 120, and this motion is transmitted by means of a coupling shaft 126 to the opposite, indirectly driven roller 122.

The base 120 of the fixed frame 118 is movable in the translation direction 112 by friction between one side of the drive rollers 122 and the other side of the rails 116a, 116 b. At its front end (as viewed in the direction of translation 112), the base frame 120 is supported on the top of the guide rails 116a and 116b by means of two non-driven guide wheels 128.

The lateral guidance of the base frame 120 on the guide device 114 is ensured by pairs of guide wheels 130, which roll on a vertical guide surface of the guide rails 116a, 116b facing each other.

The base frame 120 furthermore comprises an approximately centrally arranged connecting beam 132 which carries two bearing blocks 134 which are arranged at right angles to the direction of translation 112 and are spaced apart from one another and on which the ends of an internal rotation shaft 136 are rotatably supported about an internal rotation axis 138 which is horizontal and perpendicular to the direction of translation 112.

As can best be seen from fig. 3, the internal rotation shaft 136 has a turntable 140 fixed thereto and carries a bearing block 142 at its front end and its rear end, wherein a rotation shaft 144 is rotatably mounted on the bearing block 142 about a rotation axis 146 perpendicular to the internal rotation axis 138.

A support 148 is fastened to the pivot shaft 144, which support carries a clamping device 150, by means of which a sliding frame 152 carrying the vehicle body can be releasably fastened to the fastening frame 118.

The sliding frame 152 comprises two sliding plates 154 extending parallel to the longitudinal axis of the vehicle body, which are connected to one another by a cross member 156. The clamping device 150 acts on a plurality of such cross members 156 in order to hold the sliding frame 152 on the fixed frame 118.

Furthermore, the cross members 156 of the sliding frame 152 have a locking device 158, by means of which the vehicle body 102 can be fastened to the sliding frame 152.

Fig. 3 shows a plurality of alternative possible outer contours of the vehicle body 102 itself.

The internal rotation shaft 136, together with the turntable 140 and the bearing block 142, forms a rotating part, indicated as 160, of the fixed frame 118, which moves together with the base frame 120 in the translational direction 112 and around the internal rotation axis 138 relative to the base frame 120 by means of an internal rotation shaft drive motor 162 provided on the base frame 120, moves together with it and is connected to the internal rotation shaft 136 via a transmission gear box, and can rotate in any rotational direction at any angle.

The rotary shaft 144, the support 148 and the clamping device 150 together form a stationary part of the holder 118, which is designated as a whole by 164, which part moves together with the rotary part 160 and thus with the base frame 120 in the translational direction 112 and is twisted relative to the rotary part 160 about the axis of rotation 146 by means of a rotary drive device, which is not shown in detail here, but is disclosed in DE10258132a 1.

The above-described transport device 110 for transporting the vehicle bodies 102 into and out of the dipping basin 108 operates on the following principle:

the vehicle body 102 is first in the standard position shown in fig. 3, in which the window openings of the vehicle body are arranged above the vehicle body floor panel assembly.

The holder 118 is then moved by means of the translatory drive motor 124 along the guide 114 up to the beginning of the immersion bath 108.

In the beginning of the immersion bath 108, the vehicle body 102 is immersed in the immersion bath 108, wherein the rotary part 160 rotates at an angle of 180 ° about the internal rotation axis 138 relative to the base frame 120.

After the pivoting movement of the pivot section 160 relative to the base frame 120 has ended, the motor vehicle body 102 is transferred from the original standard position into the front end pivoted position shown in fig. 6, in which the window openings of the motor vehicle body 102 are arranged below the motor vehicle body floor group.

In this immersion position, which is reached after the end of the rotational movement of the rotary part 160, the vehicle body 102 is completely immersed in the immersion bath 108.

The base 120 of the holder 118 is located completely above the liquid level 106 in the immersed position of the vehicle body 102. In the fully immersed state, the vehicle body 102 is moved in the translational direction 112 by the immersion bath 108, wherein the translational movement of the base frame 120, which is driven by the translational drive motor 124, is continued. .

In the event that the vehicle body 102 reaches the end region of the immersion bath 108 as a result of the translational movement of the base frame 120 along the guide 114, the vehicle body 102 is again conveyed out of the immersion bath 108, wherein the rotary part 160 rotates at an angle of 180 ° about the internal rotation axis 138 relative to the base frame 120.

This outward rotational movement of the rotating portion 160 may be performed in the same rotational direction as the inward rotational movement or in the opposite rotational direction to the inward rotational movement.

In order to deposit the paint particles contained in the paint liquid of the immersion bath 108 on the surface to be painted of the vehicle body 102, the vehicle body 102 is exposed to the cathodic potential of an electric field during its passage through the immersion bath 104, which electric field is generated between the vehicle body 102 on the one hand and an electrode 166, which is arranged in a dialysis chamber on both sides (not shown) of the transport path of the vehicle body 102 in the immersion bath 108 and is exposed to the anodic potential of the electric field, on the other hand.

To generate this potential difference between the vehicle body 102 and the electrode 166, a power supply 168 of the electrocoating installation 100 shown in fig. 1 and 2 is used.

As can be seen from fig. 1, the supply device 168 comprises a three-phase transformer 170 which is connected on the primary side via a primary-side switch 172 to the three-phase voltage of the power supply system, which has an amplitude of, for example, approximately 10kV, and on the secondary side via a secondary-side switch 174 to three inputs of an uncontrolled three-phase diode rectifier bridge circuit B6 (designated by reference numeral 176).

The rectifier bridge circuit 176 is followed by a filter circuit 178 to pre-filter the unidirectional output voltage of the rectifier bridge circuit 176.

The filter circuit 178 may include, inter alia, a choke 180 and a capacitor 182.

The output voltage of the filter circuit 178 is about 500V at maximum. The output current of the filter circuit 178 is about 4000A at maximum.

As can be seen from fig. 1, the cathode of the output voltage of the filter circuit 178, which is used as the intermediate output voltage of the power supply 168, is connected to the metal housing of the immersion bath 104 and is connected to common ground.

The same pole is furthermore connected to a first contact rail 184, which runs along the translation direction 112 from the input region of the immersion bath 108 to the output region of the immersion bath 108 over substantially the entire length of the immersion bath 108.

The anode of the intermediate output voltage is connected to an electrode 166 disposed within the bath 108 and thus on the anode.

The same pole is furthermore connected to a second contact rail 185, which runs along the translation direction 112 from the input region of the immersion bath 108 to the output region of the immersion bath 108 over substantially the entire length of the immersion bath 108 and is arranged substantially parallel to the first contact rail 184.

In order to provide a cathode potential to the vehicle bodies held in each case on the holding frame 118, each holding frame 118 comprises a current control unit 186 which is arranged on the base frame 120 of the holding frame 118 and is electrically conductively connected to the first contact rail 184, for example via a first sliding contact 188, and to the second contact rail 185 via a second sliding contact 189.

As can be seen from fig. 4 and 5, for example, the first contact rail 184 may be disposed on the right side of the conveyance stroke of the mount 118 and the second contact rail 185 may be disposed on the left side of the conveyance stroke of the mount 118.

The first sliding contact 188 is held on the base frame 120 by an insulator 204 and comprises a plurality of contact holders 206 (for example, of carbon contacts) which slide along the first contact rail 184 and are held in contact with the first contact rail 184 by means of flexible cables or flexible printed circuit boards 208 and are electrically conductively connected to the current control unit 186 which is also held on the base frame 120.

The second sliding contact 189, via which the current control unit 186 is electrically conductively connected to the second contact track 185, is identical in construction to the first sliding contact 188 and comprises in particular a plurality of contact sockets 206 and a flexible cable or a flexible printed circuit board 208.

The details of the current control unit 186 are described below with reference to the block circuit diagram of fig. 2.

Each current control unit 186 comprises a switching element 190, which is connected with its first input to the sliding contact 188 and with its second input to the sliding contact 189, and a regulating circuit 192, which is connected with its output to a control input of the switching element 190 and triggers the switching element with a control voltage consisting of rectangular pulses with a repetition frequency of, for example, approximately 20kHz and a variable width and thus a variable duty cycle.

The switching element 190 cuts off the intermediate output voltage supplied to the same input terminal at a clock predetermined by the control voltage and has a pulse width predetermined by the control voltage, so that the output voltage of the switching element is a pulse voltage with a repetition frequency of the control voltage.

The output voltage of the switching element 190 is filtered by a filter circuit 196 connected downstream of the rectifier 194, which circuit comprises, for example, an LC component with a choke and a capacitor, so that the output voltage of the filter circuit 196 is a substantially constant direct voltage with a very low residual ripple, for example, in the range of approximately 1%.

This output voltage is supplied as the actual value to a first input of the regulating circuit 192.

The setpoint value of the control circuit 192 compared to the actual value is supplied by a setpoint value transmitter 198 to a second input of the control circuit 192.

The duty cycle of the control voltage sent by the regulating circuit 192 to the switching element 190 is determined by the regulating circuit 192 in dependence on the difference between the actual value and the nominal value of the output voltage.

A memory can be present on the setpoint value transmitter 198, from which a predefined temporal output voltage profile is recalled as a temporally changing setpoint value.

In this way, a regulated output voltage following a predefined temporal output voltage profile can be generated by means of the current control unit 186.

In this way, the potential difference existing between the vehicle body 102 and the electrodes 166 of the electrocoating installation 100 can be temporally changed in a predetermined manner for the relevant vehicle body 102 alone during the passage of the vehicle body 102 through the immersion bath 108.

In particular, the temporal distribution of the output voltage of the current control unit 186 can be controlled depending on the type of vehicle body 102 respectively associated with the current control unit 186, by selecting, by the setpoint value transmitter 198, one output voltage distribution from the plurality of output voltage distributions stored in its memory which is associated with the respective type, and changing the setpoint value transmitted to the control circuit 192 accordingly in time.

Information about the type respectively associated with the vehicle bodies 102 arranged on the fastening devices 118 can be transmitted via the data bus of the central computer to the setpoint value transmitter 198.

Alternatively, it is also possible that the current control unit 186 can also have a sensor which determines the type of the vehicle body 102 by interacting with an identifier attached to the vehicle body 102.

The outputs of the filter circuit 196 of the current control unit 186 can be connected directly to the respective vehicle body 102 in order to apply a pulse-free direct voltage to the vehicle body.

But it is also possible, as shown in fig. 2, that the current control unit 186 comprises a pulse-former 200 which is connected after the filter circuit 196 and which generates from the filtered output voltage of the filter circuit 196 a rectangular pulse sequence with a repetition frequency in the range of, for example, about 1kHz to about 10 kHz. The output of the pulse former 200 is connected to the vehicle body 102, so that an output voltage of such pulses is applied to the vehicle body 200.

Such a pulsed output voltage can lead to better painting results, in particular in the case of hollow bodies being painted.

Suitable pulse formers are known per se, so that a description of such a circuit is not given here.

The electrically conductive connection of the output of the pulse former 200 to the vehicle body 102 can be realized, for example, by a contact rail 210 which is held on the base side of the holder 118 and runs parallel to the translation direction 112, is held on the base by an insulator 212, and is connected to the output of the pulse former 200 by a cable (not shown).

The end of the internal shaft 136 facing the contact rail 210 extends to the vicinity of the contact rail 210 and is electrically conductively connected to the contact rail 210 at its end face close to the contact rail 210 via an insulator 214, a plurality of contact receptacles 216 arranged in a rotationally fixed manner on the insulator 214 and thus on the internal shaft 136, and is guided out on the surface of the contact rail 210 close to the contact receptacles 216 during the rotational movement of the internal shaft 136 about the internal shaft axis 138.

The contact base 216 is electrically connected to a cable (not shown) which is guided through the insulator 214 into the interior of the inner spindle 136 and extends through the inner spindle 136 as far as the longitudinal center plane of the rotary part 160. In the area of the longitudinal center plane of the rotary part 160, the cable passes out of a hole in the housing of the internal rotation shaft 136 and from there extends to a contact point on the vehicle body 102. Due to its flexibility, the cable can also follow the rotation axis 146 when the vehicle body 102 is deflected.

As the electronic switch in the switching element 190, a high power transistor is preferably used.

Such high-power transistors can be designed in particular as field effect transistors or as igbts (insulated Gate Bipolar transistors).

The switching element 190 further comprises a self-oscillating diode 202.

In the electric field generated between the vehicle body 102 and the electrode 166 within the bath 108, paint particles migrate to the vehicle body 102 and deposit on its surface.

By assigning each holder 118 and thus each vehicle body 102 a respective current control unit 186, which moves simultaneously with the respective holder 118, to each individual vehicle body 102, the output voltage can be supplied individually, so that the output voltage and/or the temporal distribution of the output current of each vehicle body 102 can be programmed individually.

Since the individual output voltages are generated for each vehicle body 102 by means of the simultaneously moving current control unit 186, there is no need to divide the first contact rail 184 or the second contact rail 185 into a plurality of segments galvanically separated from one another in the translation direction 112.

All the problems associated with the transition of the vehicle body 102 from one track segment to the next are also eliminated.

In particular, switchable contact elements, such as, for example, coupled thyristors, are not required for the electrically conductive connection of the successive track sections to one another in the direction of translation 112 during the transition of the vehicle body 102 from one track section to the subsequent track section.

The sensors required for detecting the approach of the vehicle body 102 to the end of a track section for controlling the transition between two successive track sections in conventional electrocoating plants can also be dispensed with.

Claims (20)

1. An electrocoating plant for painting workpieces, in particular automobile bodies (102), comprising: at least one immersion bath (108), in which at least one electrode (166) transport device (110) is provided, which transports the workpieces into the immersion bath (108) and out of the immersion bath (108); and a power supply device (168) which generates an output voltage, in particular a DC output voltage, from an AC input voltage, one output potential of which is applied to at least one workpiece to be painted and the other output potential of which is applied to at least one electrode (166) arranged in the dip bath (108), characterized in that the power supply device (168) comprises at least one current control unit (186) which, together with the workpieces assigned to the current control unit (186), is moved through at least one section of the electrophoretic painting installation (100) and supplies the workpieces assigned to the current control unit (186) with the output potential.

2. The electrocoating installation as claimed in claim 1, wherein the conveying device (110) comprises a plurality of holders (118) on which a workpiece to be painted is arranged in each case, and a current control unit (186) is assigned to each holder (118) and supplies the workpiece arranged on the associated holder (118) with an output potential.

3. The electrocoating installation according to claim 2, wherein a current control unit (186) is provided on each holder (118) and supplies an output potential to the workpieces arranged on the relevant holder (118).

4. The electrocoating facility as claimed in one of claims 1 to 3, wherein the electrocoating facility (100) comprises a plurality of current control units (186), and the output potential provided by each current control unit (186) is independent of the output potential provided by the respective other current control unit (186).

5. The electrocoating installation according to one of claims 1 to 4, wherein each current control unit (186) controls or regulates the output voltage and/or the output current for the assigned workpieces on the basis of a type-specific predefined voltage profile or current profile depending on the workpiece type.

6. The electrocoating installation according to one of claims 1 to 5, wherein the power supply device (168) comprises at least one contact rail (184, 185) to which at least one current control unit (186) can be connected.

7. The electrocoating installation as claimed in claim 6, wherein the power supply device (168) comprises a rectifier circuit (176) which produces an intermediate output voltage from an alternating input voltage, which voltage is applied to a contact rail (184) which can be connected to at least one current control unit (186).

8. The electrocoating installation according to claim 7, wherein a further potential of the intermediate output voltage is applied to at least one electrode (166) in the at least one dip-bath (108) and/or to a further contact rail (185) which can be connected to the at least one current control unit (186).

9. The electrocoating installation according to claim 7 or 8, wherein the rectifier circuit (176) comprises a preferably uncontrolled diode rectifier bridge.

10. The electrocoating installation according to one of claims 7 to 9, wherein the rectifier circuit (176) comprises a filter circuit (178) for reducing the residual ripple of the intermediate output voltage.

11. The electrocoating plant according to one of claims 6 to 10, wherein at least one contact rail (184, 185) is assigned to at least one dip-bath (108) of the electrocoating plant (100), to which at least one current control unit (186) can be connected and which extends without transition over the length of the dip-bath.

12. The electrocoating installation according to one of claims 1 to 11, wherein the current control unit (186) comprises a switching element (190) which converts a switching element input voltage supplied to the switching element (190) into a switching element output voltage oscillating at a clock frequency.

13. The electrocoating facility of claim 12, wherein the switching element (190) comprises at least one field effect transistor and/or at least one IGBT.

14. The electrocoating facility of claim 12 or 13 wherein the oscillating switching element output voltage has a controllable duty cycle.

15. The electrocoating installation according to one of claims 12 to 14, wherein the current control unit (186) has a regulating circuit (192) which activates the switching element (190) as a function of the rated output voltage.

16. The electrocoating facility of one of claims 12 to 15 wherein the clock frequency is at least about 10kHz, preferably at least about 20 kHz.

17. The electrocoating facility of one of claims 1 to 16, wherein the clock frequency is up to about 200kHz, preferably up to about 100 kHz.

18. The electrocoating facility of one of claims 1 to 17, wherein the current control unit (186) comprises a filter circuit (196).

19. The electrocoating facility as claimed in one of claims 1 to 18, wherein the current control unit (186) comprises a pulse-forming circuit (200).

20. Mount for an electrocoating installation (100) according to one of claims 1 to 19, characterised in that the mount (118) has a current control unit (186) for supplying an output potential to workpieces arranged on the mount (118).