CN115287733A

CN115287733A - Method for operating a processing device, processing device and computer program product

Info

Publication number: CN115287733A
Application number: CN202210473299.7A
Authority: CN
Inventors: 马库斯·拉姆塞尔; 米夏埃尔·迪特里希; 塞巴斯蒂安·布罗西; 延斯·霍夫曼
Original assignee: Duerr Systems AG
Current assignee: Duerr Systems AG
Priority date: 2021-05-03
Filing date: 2022-04-29
Publication date: 2022-11-04
Also published as: CN219315120U; DE112022002358A5; US20240141539A1; EP4334512A1; DE102021111415A1; WO2022233362A1

Abstract

The invention relates to a method for operating a treatment system (100) and to a treatment system for the electrophoretic dip coating, in particular dip painting, of a metallic workpiece (40), in particular a vehicle body, in a dip bath (30) filled with paint, wherein a relative movement between the workpiece (40) and a current rail (21) is carried out in the dip bath (30), wherein a voltage is applied to the workpiece (40), and wherein the workpiece (40) is supplied with current at least temporarily from at least one current rail section (22, 24, 26) of the current rail (21) while the workpiece (40) is in the region of action of at least one current rail section (22, 24, 26). The application also relates to a processing device and a computer program product.

Description

Method for operating a processing device, processing device and computer program product

Technical Field

The present application relates to a method for operating a treatment plant for the electrophoretic dip coating of metal workpieces, in particular vehicle bodies, as well as to a treatment plant and a computer program product for carrying out the method.

Background

Vehicle bodies are treated using an electrophoretic dip treatment apparatus, such as a cathodic dip treatment apparatus (KTL apparatus), in which they are pretreated and/or painted, for example, by being immersed in a dip bath in which a coating is applied by means of electrophoresis. Electrophoretic deposition (EPD) is a widely used industrial process in which colloidal particles are deposited onto a workpiece as an electrode under the influence of an electric field. A workpiece (e.g. a vehicle body) is immersed in an electrically conductive aqueous impregnating varnish and a direct voltage field is applied between the workpiece and a counter electrode. The basic principle of electrophoretic dip-coating is: a water-soluble binder is precipitated on the surface of the workpiece connected as an electrode, and a closed adhesive paint film is thereby produced.

Disclosure of Invention

The object of the present application is to create a method for operating a treatment system for the electrophoretic dip coating of metal workpieces, in particular vehicle bodies, by means of which better coating results can be achieved.

Another object is to create a treatment device for electrophoretic dip coating, with which a better coating result can be achieved.

Another object is to create a computer program product by means of which the improved method can be performed.

These objects are achieved by the features of the independent claims. Advantageous embodiments and advantages of the application result from the further claims, the description and the drawings.

The features mentioned in the claims can be combined with one another in a technically meaningful manner and can be supplemented by explanatory facts in the description and by details in the drawings, in which further embodiments of the application are indicated.

A method for operating a treatment system for the electrophoretic dip coating, in particular dip painting, of a metal workpiece, in particular a vehicle body, in a dip bath filled with paint is proposed, wherein a relative movement between the workpiece and a current rail is carried out in the dip bath, wherein a voltage is applied to the workpiece, and wherein the workpiece is supplied with current at least temporarily from at least one current rail section of the current rail while the workpiece remains in the region of action of the at least one current rail section.

The current rail is subdivided into individual current rail sections. There is always only one body on each current rail section, the length of each current rail section being smaller than the tact distance (taktab stand) of the bodies arranged in succession.

The current flowing to each current rail is determined by a corresponding measuring device of the current supply unit. During the treatment, the workpieces are therefore each arranged only in the region of the current rail section. The current rail sections can be longer or shorter than the workpieces, but are preferably always shorter than the clock interval between the workpieces.

The electrophoretic dip coating may be cathodic dip coating in which the workpiece to be coated is turned on as a cathode, or may be anodic dip coating in which the workpiece to be coated is turned on as an anode. For cathodic dip coating, the electrodes are filled with anolyte as an electrolyte. For anodic dip coating, there is no need for any separate anolyte system as is required for cathodic dip coating.

According to an advantageous embodiment of the method, the current supplied to the workpiece can be regulated.

The current for the current regulation can advantageously be determined in each current rail section. In the case of a current supply unit comprising modular rectifier modules, the current regulation advantageously also makes it possible to simply preset the desired coating current for each current rail section. Therefore, a better coating effect can be realized on the processed vehicle body.

According to an advantageous embodiment of the method, the workpiece is subjected to a voltage by means of at least two electrically co-directional electrodes arranged in the immersion bath in the region of action of at least one current rail section, wherein at least one rectifier module is connected to at least one of the electrodes, wherein the current supplied to the workpiece is the sum of the current components supplied by the individual rectifier modules, and wherein a voltage setpoint value, which is adjusted jointly for the individual rectifier modules in the workpiece region, is derived from a preset current setpoint value of the total current supplied to the workpiece, and the voltage setpoint value is preset for the individual rectifier modules.

For electrophoretic dip coating, in particular dip coating, it may be expedient to use separate rectifier modules for the current supply to the electrically equidirectional electrodes. For supplying direct current, each of these rectifier modules may be electrically connected to one electrode or to a group of electrodes, or a plurality of rectifier modules may be connected to a common electrode. By the modular construction, the voltage in the immersion bath can be controlled or regulated very precisely.

In the treatment section of the vehicle body, which also corresponds to the current rail section, a plurality of electrodes are generally used, which can be arranged on both sides of the vehicle body in order to achieve a beneficial treatment effect. Typically, ten to sixteen electrodes may be preset for flat or semicircular electrodes. In the case of circular electrodes, up to forty electrodes can be preset. Of course, more or fewer electrodes may be preset depending on the device.

All rectifier modules have a common pole, in the case of cathodic coating a common negative pole, and in the case of anodic coating a common positive pole, which is connected to the vehicle body via a current rail comprising individual current rail sections.

Advantageously, a total current for processing the vehicle body, which is formed by the sum of the individual current component values of the at least one electrode and of the at least one rectifier module supplied thereto, can thereby be preset and regulated. In particular, a plurality of rectifier modules can be controlled and/or regulated independently of one another. In this way, the energized operating mode of the processing unit can be advantageously set and switched.

According to one advantageous embodiment of the method, the same mean voltage setpoint value is predefined for the rectifier modules, and the voltage across the rectifier modules is regulated to a respective predefined total current setpoint value.

The body is connected to a common pole of the rectifier module via a current rail. The through current to the current rail is measured and corresponds to the current consumption of the vehicle body. Switching from voltage regulation to current regulation. For example, the average voltage of all electrodes in the body region (excluding the start and follow-up phases of the process) can be calculated in the programmable logic controller program of the control unit and assigned to the currently occupied current rail section.

During current regulation, all electrodes in the process zone (including the start-up and follow-up sections) maintain the same voltage rating. The voltage is regulated to achieve the desired current rating.

In this case, the voltage can be varied between two nominal values, i.e. between the lowest voltage of the current regulation and the highest voltage of the current regulation.

According to one advantageous embodiment of the method, for a plurality of current rail sections arranged in succession in the transport direction, a proportional integral derivative control (PID-Regelung) can be applied to each current rail section, wherein the average voltage of the respectively preceding current rail section is used as an initial value for the proportional integral derivative control.

Thus, separate pid control can be applied for each current rail section and matched as required. For example, the average voltage of the preceding current rail section can always be set as the initial value of the regulation, the so-called Y-offset value. This ensures that the voltage is constantly regulated over the entire transport path and voltage jumps can be avoided.

During the leaching of the vehicle body from the coating of the bath, the current regulation is stopped and the electrode either retains its current voltage or is applied with a special leaching voltage.

According to one advantageous embodiment of the method, a lower limit voltage and an upper limit voltage are predefined for the current regulation. Thus, during current regulation, the voltage may vary between two nominal values, i.e. between the lowest voltage of the current regulation and the highest voltage of the current regulation. The voltage is preset and the current component varies between 0A and the highest possible current component of each rectifier module. At the start of coating, the voltage is increased from 0V to the desired target value by a settable ramp.

According to an advantageous embodiment of the method, the workpiece is processed by means of charge quantity regulation by regulating the current flowing through the current rail section to a predefined charge setpoint value.

Since the coating particles to be deposited, in particular paint particles, are coated by means of current transport, the total charge is a measure for the thickness of the coating of the deposited coating material (for example of the deposited paint).

Advantageously, the charge amount adjustment can be such that the same charge amount, i.e. the amount of coating material from the paint, is always deposited on each vehicle body. For example, fluctuations in the paint temperature can be compensated automatically by the charge quantity controller, so that all vehicle bodies to be painted, in particular painted, have a beneficial painting effect. In this way, the paint consumption and the coating quality can be optimized.

From the settable painting time, the charge quantity regulation can advantageously be activated. For this purpose, for example, the amount of charge missing to achieve the desired charge rating and the remaining painting time until the vehicle body begins to leach out of the paint can be determined.

Advantageously, the amount of charge released by the rectifier module during painting can thus be kept constant. This ensures that a favorable coating effect is ensured for all vehicle bodies.

By adjusting the charge quantity, the coating layer thickness can be optimized and kept constant. In this way, material costs can be saved and quality problems due to defective coating can be avoided during the coating process.

According to an advantageous embodiment of the method, the current setpoint value for the charge quantity regulation can be determined as a quotient of the missing charge quantity and the remaining processing time.

Once the charge amount adjustment is activated, the coating current is adjusted. The current rating is continuously calculated to achieve the desired amount of charge:

current rating = delta charge/delta time,

or desired units on the tape:

current rating [ a ] = missing charge [ Amin ] × 60/remaining coating time [ s ]

If the charge quantity regulation is activated, the total current flowing through the vehicle body is regulated to the calculated nominal value. The voltage is automatically varied between a settable minimum and maximum value.

At the end of the coating process, the charge reached is checked and compared with a predetermined limit value. If the limit is exceeded or undershot, a corresponding warning message or fault message can be issued.

According to one advantageous embodiment of the method, the charge setpoint value in the charge quantity regulation can be adapted by means of adaptive regulation, wherein the regulation is carried out as a function of the process parameters. In particular, the adjustment may be effected in accordance with at least one of the following parameters of the process: coating parameters, in particular binder content, pigment content, solvent content, pH value, conductivity of the electrolyte, in particular of the anolyte. For cathodic dip coating, the electrodes are filled with an anolyte. For anodic dip coating, acid is generated on the workpiece and no separate anolyte system is required as is required for cathodic dip coating.

In another step, additional parameters may be taken into account. For this purpose, adaptive control can be used, which automatically adapts the charge rating of the vehicle body by means of external process parameters.

The external parameters can be, in particular, coating parameters such as binder content, pigment content, solvent content, pH value, electrical conductivity and electrical conductivity of the electrolyte, in particular of the anolyte. The correlation between these external parameters and the charge consumption can be stored, for example, in a mathematical formula in a programmable logic controller program of a control unit of the current supply unit.

If, for example, the pH of the coating is above the nominal value, the charge nominal value can be lowered by a certain charge value. If, on the other hand, the pH of the coating is below the nominal value, the charge nominal value can be increased by a certain amount.

According to an advantageous embodiment of the method, the charge rating during the charge quantity regulation can be adapted as a function of the measured thickness of the coating layer deposited from the coating material onto the workpiece, in particular the thickness of the coating layer comprising coating material particles.

Alternatively, the layer thickness of each vehicle body can be determined automatically by means of a layer thickness measurement after the electrocoating. If the layer thickness is too high, the charge rating is automatically lowered. If the layer thickness is too low, the charge rating is automatically increased.

According to one advantageous embodiment of the method, at the start of the treatment of the workpiece, the nominal voltage of the rectifier module is increased to the voltage nominal value via a settable voltage ramp, so that the treatment takes place by means of voltage regulation.

In this way, it is advantageously possible to adjust the starting current which rises very steeply at the start of the treatment. As the thickness of the coating increases, the current decreases as the insulating effect of the applied coating (particularly paint) increases. This value can advantageously be set higher than the voltage rating.

According to an advantageous embodiment of the method, the workpiece can be processed at predetermined time intervals by means of voltage regulation and subsequently by means of current regulation in combination with charge regulation until a predetermined charge setpoint value is reached.

By means of this control strategy, a relatively rapid coating with a first coating thickness can advantageously be achieved by voltage control, and the coating can subsequently be continued by subsequent charge control until the desired coating thickness is reached.

According to an advantageous embodiment of the method, the voltage setpoint values of the rectifier modules, which supply the electrodes assigned to the individual regions in the transport direction, can be adapted in order to treat these regions of the workpiece in a targeted manner.

By means of the modular construction of the current supply unit, which comprises individual rectifier modules, individual body regions can be influenced in a targeted manner. For this purpose, the voltage in a specific body region is increased or decreased, in order to influence the layer thickness, for example, by a maximum voltage matching of ± 20%.

In this case, the body region can expediently always be greater than the distance between the two electrodes. Advantageous for this mode of operation are small electrodes (such as circular electrodes) and as many rectifier modules as possible, the immersion bath can thus be subdivided into a plurality of small voltage regions.

According to a further aspect of the application, a treatment plant is proposed for the electrophoretic dip coating, in particular dip painting, of metal workpieces, in particular vehicle bodies, in a dip bath filled with paint, in order to carry out the method as described in the foregoing.

The processing device comprises at least: at least two electrodes, which are electrically co-directional, which are arranged in particular on both sides of the workpiece; a current rail which is arranged in the transport direction of the workpiece in the immersion bath and is subdivided into individual current rail sections, wherein the current rail is electrically connected to the workpiece; and at least one current supply unit comprising at least one rectifier module, wherein a pole of the at least one rectifier module is electrically connected with at least one of the at least two co-directional electrodes, and wherein another pole of the at least one rectifier module is electrically connected with the current rail, and the at least two electrically co-directional electrodes apply a voltage to the workpiece.

The current rail is subdivided into individual current rail sections. During the treatment, only one workpiece, for example a vehicle body, is located on each current rail section, wherein the length of each current rail section is smaller than the pitch of the sequentially arranged vehicle bodies. The current flowing to each current rail is determined by a corresponding measuring device of the current supply unit. During the treatment, the workpieces are therefore each arranged only in the region of the current rail sections which are shorter than the clock pitch.

According to an advantageous embodiment of the treatment device, the treatment device can be designed for current regulation of the current supplied to the workpiece.

For the current regulation in each current rail section, the current is determined. In the case of a current supply unit comprising modular rectifier modules, the current regulation advantageously also makes it possible to easily preset the desired coating current for each current rail section. In this way, a better coating effect can be achieved on the treated vehicle body.

According to an advantageous embodiment of the treatment device, the at least one current supply unit can be designed to: the rectifier modules are each operated individually by means of voltage regulation.

The body is connected to a common pole of the rectifier module via a current rail. The current flow to the current rail is measured and corresponds to the current consumption of the vehicle body. Switching from voltage regulation to current regulation. For example, the average voltage of all electrodes in the body region (excluding the start and follow-up phases of the process) can be calculated in the programmable logic controller program of the control unit and assigned to the currently occupied current rail.

According to an advantageous embodiment of the treatment device, the at least one current supply unit can be designed to: the rectifier module is operated by means of a current regulation in combination with a charge quantity regulation, the current through the current rail section.

Since the coating particles from the coating are applied by means of current transport, the total charge represents the size of the coating thickness of the applied coating (in particular the coating comprising the coating particles).

Advantageously, the charge amount adjustment can ensure that the same charge amount is always deposited for each vehicle body. For example, fluctuations in the paint temperature can be compensated automatically by the charge quantity controller, so that all vehicle bodies to be painted have a beneficial painting effect. In this way, the paint consumption and the coating quality can be optimized.

According to an advantageous embodiment of the treatment device, at least one of the current supply units can be designed to: during a first time interval, the rectifier module is operated by means of voltage regulation, and during a second time interval, the rectifier module is operated by means of current regulation in combination with charge quantity regulation until a predefined charge nominal value is reached.

The charge quantity control can be activated appropriately from the settable coating time. For this purpose, for example, the missing charge for achieving the desired charge rating and the remaining painting time until the vehicle body begins to leach out of the paint from the bath can be determined.

By charge quantity regulation, the deposited layer thickness can be optimized and kept constant. In this way, material costs can be saved and quality problems due to defective coating can be avoided during the coating process.

By means of this control strategy, a relatively rapid coating with a first coating thickness can advantageously be achieved by voltage control, and subsequently the coating can be continued by subsequent charge measurement until the desired coating thickness is reached.

According to a further aspect of the application, a computer program product is proposed for carrying out the method according to the application for operating a treatment plant for the electrophoretic dip coating, in particular dip painting, of a metal workpiece, in particular a vehicle body, in a dip bath filled with paint, wherein the workpiece is moved in a transport direction along a current rail and electrodes supplied by a rectifier module. The computer program product comprises: at least one computer readable storage medium having program code instructions stored thereon, wherein the program code instructions, implementable by a data processing device, cause: the workpiece is supplied with current at least temporarily from the at least one current rail section while the workpiece remains in the region of action of the at least one current rail section of the current rail.

According to an advantageous embodiment of the computer program product, the program code instructions which can be implemented by the data processing device can cause: processing the workpiece at least temporarily by means of current regulation by presetting a current setpoint value for a current rail section of the current rail, wherein the same regulated voltage setpoint value is preset for the rectifier module and the voltage is regulated to the preset current setpoint value; and/or by regulating the current flowing through the current rail section to a predetermined charge setpoint value, so that the workpiece is processed by means of charge quantity regulation; and/or in a first time interval, the workpiece is processed by means of voltage regulation, and in a second time interval, the workpiece is processed by means of current regulation combined with charge regulation until a preset charge rated value is reached; and/or for the targeted treatment of individual regions of the workpiece, the voltage ratings of the rectifier modules which supply the electrodes in these regions are adapted.

Advantageously, the total current for processing the vehicle body, which is formed by the sum of the individual current component values of the individual electrodes and of the rectifier modules supplying them, can thus be preset and regulated, wherein these are controlled independently of one another.

In this way, the energized operating mode of the processing unit can be advantageously set and switched.

Drawings

Other advantages result from the following description of the figures. Embodiments of the present application are shown in the drawings. The figures, description and claims contain a large number of combined features. Those skilled in the art will also suitably examine the features individually and combine them into useful other combinations.

The figures show by way of example:

FIG. 1 illustrates one embodiment of the present application including a treatment facility;

FIG. 2 shows a schematic diagram of a processing device according to an embodiment of the present application, including exemplary values of current regulation;

FIG. 3 shows a schematic diagram of a processing apparatus including example values for rating matching in voltage regulation to weight individual workpiece regions according to an embodiment of the present application;

FIG. 4 shows a schematic diagram of a processing apparatus including example values for rating matching in current regulation to weight individual workpiece regions according to an embodiment of the present application; and is

Fig. 5 shows a typical voltage profile/current profile during a process in a charge-regulated operating mode of a method according to an embodiment of the present application.

Detailed Description

The drawings are only examples and should not be construed as limiting.

Before describing the present application in detail, it is noted that it is not limited to the corresponding components of the apparatus and the corresponding method steps, as such components and methods may vary. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of use. In addition, if a singular or indefinite article is used in the specification or in the claims, it also refers to a plural of that element unless a different statement is made herein.

Directional terms used hereinafter with concepts such as "left", "right", "upper", "lower", "front", "rear", etc. are used only for better understanding of the drawings, and do not represent a limitation of generality in any way. The components and elements shown, as well as their design and use, may be varied under the trade-offs of those skilled in the art and may be adapted to the respective application.

Fig. 1 shows one embodiment of the present application including a processing device 100.

The treatment installation 100 for the electrophoretic (e.g. cathodic) dip-coating of a metal workpiece 40, in particular a vehicle body, in a paint-filled bath 30 comprises a plurality of electrodes 32, in particular arranged on both sides of the workpiece 40. Relative movement between the workpiece 40 and the current rail 21 takes place in the immersion bath 30, i.e. for a fixed current rail 21, the workpiece in the immersion bath 30 is moved in the transport direction 42 between the likewise fixed electrodes 32.

For cathodic dip coating, the workpiece 40 to be coated is turned on as a cathode and the electrode is filled with an anolyte.

Further, the processing device 100 comprises a current rail 21 which is arranged within the immersion bath 30 along the transport direction 42 of the workpiece 40 and which is subdivided into individual

current rail sections

22, 24, 26. The length 46 of the

current rail sections

22, 24, 26 can be adapted to the length 44 of the workpiece 40 in the transport direction 42. The

current rail sections

22, 24, 26 can be as long as the workpiece 40, but can also be longer or shorter, but are preferably always shorter than the clock intervals.

The current rail 21 is electrically connected to the workpiece 40, for example, by a cable. However, this is not shown in fig. 1.

There is always only one body on each

track section

22, 24, 26, the length of each

track section

22, 24, 26 being smaller than the pitch of the bodies arranged one behind the other. The current flowing to each

current rail section

22, 24, 26 is determined by the corresponding measuring device 18 of the current supply unit 10. During the treatment, the workpieces 40 are therefore each arranged only in the region of the

current rail sections

22, 24, 26, which corresponds, for example, to the length of the workpiece 40. The current is determined for current regulation within each

current rail section

22, 24, 26.

In the case of a current supply unit 10 comprising modular rectifier modules 12, the current regulation advantageously also makes it possible to simply preset the desired coating current for each

current rail section

22, 24, 26. Therefore, better coating effect can be realized on the processed vehicle body.

For electrophoretic dip painting, it may be appropriate to use separate rectifier modules 12 for the current supply of the electrodes 32. Each of these rectifier modules 12 supplies a direct current to one electrode 32 or a group of electrodes 32. By the modular construction, the voltage in the immersion bath 30 can be controlled very precisely. Alternatively, a plurality of rectifier modules 12 may also be provided for one electrode 32.

In the body treatment sections, which also correspond to the

current rail sections

22, 24, 26, typically ten to sixteen flat or semicircular electrodes 32 are used, respectively, which can be arranged on both sides of the body in order to achieve a beneficial treatment effect. In case of a circular electrode 32, it is also possible to preset more electrodes, for example up to forty electrodes. More or fewer electrodes may also be preset, respectively.

All rectifier modules 12 have a common pole 16, which is connected to the vehicle body via a current rail 21 having individual

current rail sections

22, 24, 26. For cathodic dip coating, the common pole 16 would be the negative pole, while for anodic dip coating, the common pole 16 would be the positive pole.

Advantageously, the total current for processing the vehicle body, which is formed by the sum of the individual current component values 75 of the individual electrodes 32 and of the rectifier modules 12 supplied thereto, can thus be preset and regulated, wherein the control is carried out independently of one another. In this way, the energized operating mode of the processing unit 100 can be advantageously set and switched.

In the embodiment in fig. 1, two current supply units 10 have a plurality of rectifier modules 12. In this case, the positive poles 14 of the rectifier modules 12 are each electrically connected to at least one electrode 32. The negative poles 16 of all the rectifier modules 12 are electrically connected to the current rail 21. Thus, a voltage can be applied to the workpiece 40 by the electrodes 32 arranged on both sides of the workpiece 40 in the coating of the bath 30.

During the treatment, the workpieces 40 are each arranged only in the region of one

current rail section

22, 24, 26.

The processing apparatus 100 is designed for current regulation of the current supplied to the workpiece 40. The current can be determined individually by the current measuring unit 18 in each

current rail section

22, 24, 26. The negative pole 16 of the rectifier module 12 is electrically connected to the

current rail sections

22, 24, 26 via the current measuring unit 18 and optionally via a coupling thyristor 28.

By means of the current supply unit 10, the rectifier modules 12 can each be operated individually by means of voltage regulation.

The rectifier module 12 can be operated by means of current regulation in combination with charge quantity regulation by means of the current through the

current rail sections

22, 24, 26.

The current supply unit 10 is designed to: during a first time interval, the rectifier module 12 is operated by means of voltage regulation, and during a second time interval, the rectifier module is operated by means of current regulation in combination with charge quantity regulation until a predetermined charge nominal value 80 is reached.

According to the method according to the present application, the current supplied by the at least one

current rail section

22, 24, 26 to the workpiece 40 is regulated at least temporarily while the workpiece 40 remains in the region of action of the at least one

current rail section

22, 24, 26 of the current rail 21.

The current supplied to the workpiece 40 is the sum of the current components supplied by the individual rectifier modules 12, wherein a voltage setpoint value 71 for the rectifier modules 12 in the region of the workpiece 40 to be coated is derived from a preset current setpoint value of the total current supplied to the workpiece 40, and the voltage setpoint value is preset for the individual rectifier modules 12.

The same mean voltage setpoint value 71 (shown in fig. 2) can be predefined for the rectifier modules 12, and the voltage across the rectifier modules 12 can be set to a predefined total current of the respective workpiece 40.

For a plurality of

current rail sections

22, 24, 26 arranged one behind the other in the conveying direction 42, for example, a proportional integral derivative control can be applied to each

current rail section

22, 24, 26, wherein the average voltage of the respectively preceding

current rail section

22, 24, 26 can be used as an initial value for the proportional integral derivative control.

Suitably, the lower and upper limit voltages may be preset for current regulation.

Thus, for each

current rail section

22, 24, 26, a separate pid control may be used. For example, the average voltage of the preceding

current rail section

22, 24, 26 can always be set as an initial value for the regulation, the so-called Y compensation value. This ensures that the voltage is constantly regulated over the entire transport path and no voltage jumps occur.

During the leaching of the body from the paint, the current regulation is stopped and the electrode 32 either retains its current voltage or is applied with a specific leaching voltage.

The body is connected to the common negative pole 16 of the rectifier modules 12 via a current rail 21. The current flow to the current rail 21 is measured and corresponds to the current consumption of the vehicle body. Switching from voltage regulation to current regulation. For example, the average voltage of all the electrodes 32 in the body region (excluding the start and follow-up phases of the process) can be calculated in the programmable logic controller program of the control unit and assigned to the currently occupied

current rail sections

22, 24, 26.

During current regulation, all electrodes 32 in the process region (including the start-up and follow-up segments) maintain the same voltage rating 71. The voltage is regulated to achieve the desired current rating.

In this case, the voltage 70 can be varied between two nominal values, namely between the lowest voltage of the current regulation and the highest voltage of the current regulation.

Fig. 2 shows a schematic diagram of a processing device 100 according to an embodiment of the present application, including example values of current regulation. The processing apparatus 100 is shown in schematic longitudinal cross-section, with the individual electrodes 32 shown as vertical, checkered rectangles. The transport unit 34 is arranged on a support body 36 and supports a vehicle body as a workpiece 40, which is immersed head-down into the immersion bath 30. The workpiece 40 is moved in a conveying direction 42, which is indicated by an arrow.

The start-up section area 52 and the follow-up section area 50 of the treatment device and the body area 54 are indicated.

During the current regulation by means of the voltage values and the current values for the respective electrode pairs of the electrodes 32 arranged on both sides of the workpiece 40, all the electrodes 32 maintain the same voltage value 70 as the rated voltage. In this case, the voltage 70 is adjusted such that the desired total current 74 is generated on the current rail 21. In the embodiment shown, a current rating of 700A is preset, which is derived from the sum of the individual current values 75 of the electrodes 32.

A schematic diagram of a processing apparatus 100 according to an embodiment of the present application is shown in fig. 3, which includes example values for rating matching during voltage regulation for weighting

individual workpiece regions

56, 58, 60.

In order to specifically treat

individual regions

56, 58, 60 of the workpiece 40, the voltage setpoint 71 of the rectifier module 12 is adapted, which supplies the electrodes 32 assigned to these

regions

56, 58, 60 in the conveying direction 42.

By virtue of the modular design of the current supply unit 10, which comprises individual rectifier modules 12,

individual body regions

56, 58, 60 can be influenced in a targeted manner. For this purpose, the voltage in the

specific body region

56, 58, 60 is increased or decreased in order to influence the layer thickness, for example, by a maximum voltage matching of ± 20%.

In this case, the

body regions

56, 58, 60 can expediently always be greater than the distance between the two electrodes. Advantageous for this mode of operation are small electrodes 32 (such as circular electrodes) and as many rectifier modules 12 as possible, the immersion bath 30 can thus be subdivided into a plurality of small voltage regions.

For this purpose, the voltage setpoint value 71 assigned to the electrodes 32 of the

regions

56, 58, 60 can be corrected by a correction value 73 for voltage matching, by means of which a matched voltage setpoint value 72 is then determined. With these matched voltage ratings 72, the processing of the workpiece 40 can be continued and the

individual regions

56, 58, 60 can be processed in a targeted manner with a higher or lower deposition rate of the coating to be applied.

In fig. 3, factors of-10% to +10% are assigned to the

individual regions

56, 58, 60, with which the respective voltage target 71 is weighted and a matching voltage target 72 is determined therefrom.

Fig. 4 shows a schematic diagram of a processing apparatus 100 according to an embodiment of the present application, including example values for rating matching during current regulation for weighting

individual workpiece regions

56, 58, 60.

The same correction value 73 as in the example of fig. 3 is the basis thereof. In this case, however, instead of the voltage setpoint 71 of the voltage regulation, the voltage setpoint 71 is adapted in the current regulation. In this case, the voltage values for the individual electrodes 32 are preset and adapted to produce the desired total current by means of current regulation.

The voltage rating 71 shown in fig. 4 with a value of xxx V is from current regulation. These values 71 are correspondingly matched by means of the correction values 73. The resulting current component 75 is listed by way of example and results in a preset current rating of 480A.

Fig. 5 shows a typical voltage profile/current profile during the processing in the processing device 100 as shown in fig. 1 in the charge-regulated operating mode of the method according to an embodiment of the application.

Advantageously, the charge amount adjustment may ensure that the same amount of charge 76 is always deposited for each body. For example, fluctuations in the paint temperature can be compensated automatically by the charge quantity controller, so that all painted vehicle bodies have a beneficial painting effect. In this way, the paint consumption and the coating quality can be optimized.

From the settable painting time 82, the charge amount adjustment can be activated appropriately. For this purpose, for example, the charge quantity Δ Q missing to achieve the desired charge setpoint value 80 and the remaining painting time Δ t until the vehicle body begins to leach out of the paint can be determined.

Advantageously, the charge quantity 76 released by the rectifier module 12 during painting can thus be kept constant. This ensures that a favorable coating effect is ensured for all vehicle bodies.

By means of the charge quantity regulation, the coating layer thickness can be optimized and kept constant. In this way, material costs can be saved and quality problems due to defective painting can be avoided during the painting process.

According to one advantageous embodiment of the method, the current setpoint value for the charge quantity regulation is determined as a quotient of the missing charge quantity Δ Q and the remaining processing time Δ t.

The voltage 70, the resulting current 74 and the charge 76 are plotted in fig. 5 as a function of time 84 during processing in the processing apparatus 100.

First, the rectifier module 12 and the electrode 32 operated thereby are operated voltage-regulated until the point in time 82 when charge regulation occurs.

At the start of the treatment of the workpiece 40, the voltage regulation is used to carry out the treatment by increasing the nominal voltage of the rectifier module 12 via a settable voltage ramp to the nominal voltage value 71.

The treatment of the workpiece 40 takes place at predetermined time intervals by means of voltage regulation and subsequently by means of current regulation in combination with charge regulation until a predetermined charge setpoint value 80 is reached.

During the voltage regulation phase, the current 74 rises steeply first, while the voltage 70 rises gently. Subsequently, the current 74 again drops to the average value, since the insulating effect of the deposited coating material occurs on the workpiece 40.

Starting from the time 82 of switching to charge regulation, the rectifier module 12 is operated in current-regulated fashion, corresponding to the determined charge quantity Δ Q still missing with respect to the charge setpoint value 80, which should be reached within the still available time Δ t. Thus, the charge 76 rises linearly over this section up to the charge nominal value 80.

The workpiece 40 is processed by charge regulation by regulating the current flowing through the

current rail sections

22, 24, 26 to a predetermined charge setpoint value 80.

The current rating for the charge quantity regulation is determined as the quotient of the missing charge quantity and the remaining processing time.

Advantageously, the charge setpoint value 80 during the charge quantity regulation can be adapted by means of adaptive regulation. For example, the adjustment may be effected in accordance with a processing parameter. In particular, the adjustment may be effected in accordance with at least one of the following parameters of the process: coating parameters, in particular solvent content, pH value, conductivity and conductivity of the electrolyte, in particular of the anolyte.

For example, the charge rating 80 during the charge regulation can also be adapted as a function of the measured thickness of the coating deposited from the coating onto the workpiece 40, in particular the thickness of the coating comprising coating particles.

Advantageously, the current supply unit 10 of the processing device 100 is connected to a computer, which executes a computer program product for carrying out the method according to the present application for operating the processing device 100 for the electrophoretic (e.g. cathodic) dip coating of a metal workpiece 40, in particular a vehicle body, in a bath 30 filled with a coating material, wherein the workpiece 40 is moved in a transport direction 42 along a current rail 21 and an electrode 32 supplied by a rectifier module 12, the computer program product comprising at least one computer-readable storage medium having program code instructions stored thereon, wherein the program code instructions executable by the data processing device cause: when the workpiece 40 is resting in the region of action of the at least one

rail section

22, 24, 26 of the rail 21, the workpiece 40 is supplied with current at least temporarily from the at least one

rail section

22, 24, 26.

Further, the program code instructions may advantageously cause: the processing of the workpiece 40 takes place at least temporarily by means of current regulation by presetting the current setpoint values for the

current rail sections

22, 24, 26 of the current rail 21, wherein the same average voltage setpoint value 71 is preset for the rectifier module 12 and the voltage is regulated to the preset current setpoint value; and/or by regulating the current flowing through the

current rail sections

22, 24, 26 to a predetermined charge setpoint value 80, so that the workpiece 40 is processed by means of charge quantity regulation; and/or in a first time interval, the workpiece 40 is processed by means of voltage regulation, and in a second time interval, the workpiece is processed by means of current regulation combined with charge regulation until a predetermined charge nominal value 80 is reached; and/or for targeted processing of

individual regions

56, 58, 60 of the workpiece 40, the voltage setpoint values 71 of the rectifier modules 12 which supply the electrodes 32 in these

regions

56, 58, 60 are adapted.

Reference numerals

10. Current supply unit

12. Rectifier module

14. Positive electrode

16. Negative electrode

18. Current measuring unit

20. Connecting wire

21. Current rail

22. Current rail section

24. Current rail section

26. Current rail section

28. Coupled thyristor

30. Immersion bath

32. Electrode for electrochemical cell

34. Transport unit

36. Support body

40. Workpiece

42. Direction of conveyance

44. Length of work

46. Current rail length

50. Follow-up section

52. Starting section

54. Vehicle body region

56. Region 1

58. Region 2

60. Region 3

70. Voltage of

71. Voltage rating

72. Adapted voltage rating

73. Correction value

74. Electric current of

75. Component of current

76. Electric charge

80. Charge rating

82. Beginning of charge amount adjustment

84. Time of day

100. And (4) processing equipment.

Claims

1. A method for operating a treatment plant (100) for the electrophoretic dip coating, in particular dip painting, of metal workpieces (40), in particular vehicle bodies, in a dip bath (30) filled with paint,

wherein a relative movement between the workpiece (40) and a current rail (21) is carried out in the immersion bath (30),

wherein a voltage is applied to the workpiece (40), and

wherein the workpiece (40) is supplied with current at least temporarily from at least one current rail section (22, 24, 26) of the current rail (21) while the workpiece (40) remains in the region of action of the at least one current rail section (22, 24, 26).

2. The method of claim 1, wherein the current supplied to the workpiece (40) is regulated.

3. Method according to claim 1 or 2, wherein the workpiece (40) is subjected to a voltage by means of at least two electrically co-directional electrodes (32) arranged in the immersion bath (30) in the region of action of at least one of the current rail sections (22, 24, 26),

wherein at least one rectifying module (12) is connected to at least one of said electrodes (32);

wherein the current supplied to the workpiece (40) is the sum of the current components supplied by the single rectifier module (12),

wherein a voltage setpoint value for the rectifier modules (12) in the region of the workpiece (40) to be coated is derived from a preset current setpoint value of the total current supplied to the workpiece (40), and the voltage setpoint value is preset for the individual rectifier modules (12).

4. Method according to any of the preceding claims, wherein the same average voltage rating (71) is preset for the rectifier modules (12) and the voltage over the rectifier modules (12) is regulated to reach the preset total current.

5. Method according to claim 4, wherein for a plurality of current rail sections (22, 24, 26) arranged one after the other in the conveying direction (42), a proportional integral derivative control is applied for each current rail section (22, 24, 26), wherein the average voltage of the respectively preceding current rail section (22, 24, 26) is used as an initial value for the proportional integral derivative control.

6. The method according to claim 4 or 5, wherein a lower and an upper voltage are preset for the current adjustment.

7. Method according to one of the preceding claims, wherein the processing of the workpiece (40) is carried out by means of charge quantity regulation by regulating the current flowing through the current rail sections (22, 24, 26) to a preset charge nominal value (80).

8. The method of claim 7, wherein the current rating for the charge amount adjustment is determined as a quotient of an amount of charge missing and a remaining processing time.

9. Method according to claim 7 or 8, wherein the charge nominal value (80) in the course of the charge amount adjustment is effected by means of an adaptive adjustment, wherein the adjustment is effected in dependence on processing parameters, in particular wherein the adjustment is effected in dependence on at least one of the following parameters of the processing course: coating parameters, in particular the binder content, the pigment content, the solvent content, the pH value, the conductivity of the electrolyte, in particular of the anolyte, and the electrical conductivity of the coating.

10. Method according to one of claims 7 to 9, wherein the charge rating (80) in the charge amount regulation is adapted as a function of the measured thickness of the coating deposited from the coating onto the workpiece (40), in particular the thickness of the coating comprising coating particles.

11. Method according to one of the preceding claims, wherein at the start of the treatment of the workpiece (40), the treatment is carried out by means of voltage regulation by increasing the rated voltage of the rectifier module (12) to a voltage rated value (71) via a settable voltage ramp.

12. Method according to one of the preceding claims, wherein the treatment of the workpiece (40) is carried out by means of voltage regulation for a preset time interval and subsequently by means of current regulation in combination with charge regulation until a preset charge rating (80) is reached.

13. Method according to one of the preceding claims, wherein, for the targeted treatment of individual regions (56, 58, 60) of the workpiece (40), the voltage rating (71) of the rectifier module (12) which supplies the electrodes (32) assigned to these regions (56, 58, 60) in the conveying direction (42) is adapted.

14. A treatment plant (100) for the electrophoretic dip coating, in particular dip painting, of metal workpieces (40), in particular vehicle bodies, in a dip bath (30) filled with paint, for carrying out the method according to any one of the preceding claims, comprising at least:

at least two electrically co-directional electrodes (32), which are arranged in particular on both sides of the workpiece (40),

a current rail (21) which is arranged within the immersion bath (30) along a transport direction (42) of the workpiece (40) and is subdivided into individual current rail sections (22, 24, 26), wherein the current rail (21) is electrically connected to the workpiece (40),

at least one current supply unit (10) comprising at least one rectifier module (12), wherein a pole (14) of at least one of the rectifier modules (12) is electrically connected with at least one of the at least two co-directional electrodes (32), and wherein another pole of at least one of the rectifier modules (12) is electrically connected with the current rail (21), and at least two co-directional electrodes (32) apply a voltage to the workpiece (40).

15. The processing apparatus according to claim 14, wherein the processing apparatus (100) is designed for current regulation of the current supplied to the workpiece (40).

16. The processing apparatus as claimed in claim 14 or 15, wherein at least one of the current supply units (10) is designed to: the rectifier modules (12) are each operated individually by means of voltage regulation.

17. The processing device according to any of claims 14 to 16, wherein at least one of the current supply units (10) is designed to operate the rectifier module (12) by means of current regulation in combination with charge quantity regulation, current through a current rail section (22, 24, 26).

18. The processing apparatus according to any of claims 14 to 17, wherein at least one of the current supply units (10) is designed to: during a first time interval, the rectifier module (12) is operated by means of voltage regulation, and during a second time interval, the rectifier module is operated by means of current regulation in combination with a charge quantity regulation up to a predefined charge nominal value (80).

19. A computer program product for carrying out a method according to one of claims 1 to 13 for operating a treatment plant (100) for the electrophoretic dip coating, in particular dip painting, of a metallic workpiece (40), in particular a vehicle body, in a dip bath (30) filled with paint, wherein the workpiece (40) is moved in a conveying direction (42) along a current rail (21) and an electrode (32) supplied by a rectifier module (12),

the computer program product comprises: at least one computer readable storage medium having program code instructions stored thereon, the program code instructions executable by a data processing apparatus to cause:

the workpiece (40) is supplied with current at least temporarily from at least one current rail section (22, 24, 26) of the current rail (21) while the workpiece (40) is in the region of action of the at least one current rail section (22, 24, 26).

20. The computer program product of claim 19, wherein the program code instructions executable by the data processing apparatus cause:

processing of the workpiece (40) is carried out at least temporarily by means of current regulation by presetting a current nominal value for a current rail section (22, 24, 26) of the current rail (21), wherein the same average voltage nominal value (71) is preset for the rectifier modules (12) and the voltage is regulated to the preset current nominal value,

and/or by supplying the workpiece (40) with the current from the current rail sections (22, 24, 26) to achieve a predetermined charge setpoint value (80), so that the workpiece (40) is processed by means of charge quantity regulation;

and/or in a first time interval, the workpiece (40) is processed by means of voltage regulation, and in a second time interval, the workpiece is processed by means of current regulation combined with charge regulation until a preset charge rated value (80) is reached;

and/or for the targeted treatment of individual regions (56, 58, 60) of the workpiece (40), the voltage ratings (71) of the rectifier modules (12) which supply the electrodes (32) in these regions (56, 58, 60) are adapted.