DE102017009969A1 - Method for operating an electrodeposition coating device and electrodeposition coating device - Google Patents

Abstract

The invention relates to a method for operating an electrodeposition coating device (1) and for determining at least one property of a paint preparation (4) for an electrodeposition coating, comprising the following steps:
Arranging a part of the paint preparation (4) in an acoustic waveguide (5);
Generating surface acoustic waves (9) in the waveguide (5) by means of a transmitter (7);
Receiving acoustic waves (9) on the waveguide (5) by means of a receiver (8) and obtaining a receiver signal;
Comparing the receiver signal and / or at least one measured variable derived from the receiver signal with at least one predetermined comparison parameter, and obtaining a comparison result, and
Determining the at least one property of the paint preparation (4) based on the comparison result.

Description

The invention relates to a method for operating an electrodeposition coating device and to an electrodeposition coating device.

Methods for operating electrocoating devices, in particular methods for operating cathode dip coating devices, as well as electrocoating devices, in particular cathode dip coating devices, are known. The disadvantage of this is that a solids content and a binder / pigment ratio in the electrocoating bath at regular intervals must be determined manually by sampling. The values determined by this method must be compared with the nominal values, and if there is a deviation from the target value, quantities for post-dosing of the binder and the pigment paste must also be calculated manually and then further added by hand to the electrocoating bath. In particular, this procedure has the disadvantage that the result in terms of the solids content and the binder / pigment ratio depends crucially on the way in which the sampling is carried out, and furthermore the quality of the calculation as well as the execution of the (Nach -) Dosage depending on the person performing, especially how carefully the person performs their work. As a result of the many manual process steps, the quality of the product depends directly on the quality of work of the person performing the work. For products with a very low manufacturing tolerance, this can be particularly problematic and lead to increased rejects.

One current option for automatically determining the solid content and binder / pigment ratio is to use two sensors, the first being a Coriolis mass flowmeter for density determination and the second sensor being a sound sensor for measuring the speed of sound. In particular, the Coriolis mass flow meter is a very expensive and associated with a high maintenance meter, so such automation of (re) dosing is not always economical. The second sensor is also associated with a high level of maintenance, so that a very expensive and especially in the absence of maintenance and a very error-prone system is formed by both sensors.

The invention is therefore based on the object to provide a method for operating an electrocoating device and an electrocoating device, wherein said disadvantages are avoided.

The object is achieved by providing the subject matters of the independent claims. Advantageous embodiments emerge from the subclaims.

The object is achieved in particular by providing a method for operating an electrodeposition coating device and for determining at least one property of a paint formulation for an electrodeposition coating, comprising the following steps: arranging a part of the paint formulation in an acoustic waveguide; Generating surface acoustic waves in the waveguide by means of a transmitter; Receiving acoustic waves at the waveguide by means of a receiver, and obtaining a receiver signal; Comparing the receiver signal and / or at least one measured variable derived from the receiver signal with at least one predetermined comparison parameter, and obtaining a comparison result, and determining the at least one property of the paint preparation from the comparison result. With the method according to the invention for operating an electrodeposition coating device, in particular the determination of a property of the paint preparation, such as, for example, the solids content and / or the binder / pigment ratio, can be automated, but without a large amount of maintenance and without high investment costs. Furthermore, it is avoided that the individual influence of a person, who would otherwise perform the sampling, affects the quality of the manufactured products. Furthermore, on the one hand, a deviation is detected immediately and not - as in the case of only regular sampling - only at the next sampling by the preferably continuous determination of the at least one property, and on the other hand, by the automated determination of the property, the period in which this Value deviates, significantly reduced. Overall, thus, a method can be created which is suitable directly for use in Industry 4.0, and in general, the product quality of the product produced by the electrocoating can be significantly increased by the particular more reliable and reproducible and faster determination of at least one property.

The use of sound waves to determine the properties of a liquid or even gaseous medium is known in principle. For example, the WO 2008/034878 A2 a device for exciting surface acoustic waves in a carrier adjacent to the medium to be examined, wherein physical or chemical properties of the medium are determined by means of the surface acoustic waves. The transmitter is preferably designed to be in the Waveguide can excite surface acoustic waves, for example in the form of Lamb waves or in the form of a hybrid of Lamb and Rayleigh waves. For example, surface acoustic wave pulses are generated in the waveguide. The surface acoustic waves excited in the waveguide partially couple out of the waveguide into the paint preparation, that is to say an at least partial conversion of the surface acoustic waves propagating in the waveguide into volume sound waves takes place in the paint preparation. Conversely, the volume sound waves excited in the paint preparation are partly reconverted back into surface sound waves in the waveguide, which can then be registered with the receiver. However, part of the surface acoustic waves excited in the waveguide also pass directly to the receiver in the waveguide and are detected there. From the resulting in the receiver receiver signal can then be closed on properties of the paint preparation. It is also conceivable that by means of the transmitter not or at least not exclusively surface waves are excited in the waveguide, but generally sound waves, for example, a longitudinal component - along the waveguide - and a transverse component - perpendicular to the waveguide - have. It is also possible that purely longitudinal waves are excited in the waveguide.

The waveguide may comprise two spaced support plates, between which the paint preparation is arranged, wherein the transmitter is preferably arranged on a first of the two support plates, wherein the receiver is arranged on a second, different from the first support plate of the two support plates. Preferably, the transmitter and the receiver - viewed in the longitudinal direction of the carrier plates and / or in the flow direction of the paint preparation in the waveguide - are arranged spaced from each other. Thus, in particular, sound waves reflected several times in the waveguide and having passed through the paint preparation several times can also be detected in the receiver.

However, the waveguide can also be formed as a hollow cylinder or tube on which - in particular on the outside and preferably offset in the longitudinal direction of the hollow cylinder to each other - the transmitter on the one hand and the receiver are arranged on the other. The paint preparation is arranged in this case in the interior of the hollow cylinder, preferably the paint preparation flows through the interior of the hollow cylinder.

It is possible that more than one transmitter and / or more than one receiver are arranged on the waveguide.

According to a development of the invention, it is provided that from the receiver signal as the at least one derived measured variable a physical quantity of the paint preparation selected from a group consisting of an acoustic density, a sound velocity, an acoustic impedance, and an acoustic transmission is derived. From these derived measured quantities it is possible in turn to conclude, in particular by comparison with the at least one predetermined comparison parameter, properties of the paint preparation, in particular the at least one property to be determined.

It is thus possible, in particular, to compare the receiver signal directly with at least one predetermined comparison parameter and to deduce therefrom the at least one property of the paint preparation to be determined. For this, the at least one particular property is preferably correlated with predetermined receiver signal patterns used as comparison parameters, so that by comparing the receiver signal with the predetermined receiver signal patterns, a current value of the property can be deduced.

Alternatively or additionally, it is possible that at least one measured variable is derived from the receiver signal, which in turn is then compared with corresponding, predetermined comparison parameters, from which reference is made to the property of the paint preparation. In this case, this property is correlated with predetermined values of the at least one measured variable as comparison parameters.

The comparison with the at least one predetermined comparison parameter preferably includes a similarity and / or identity check, wherein as comparison result that predetermined comparison parameter or comparison parameter value is returned which is closest to or closest to the receiver signal and / or the at least one measured variable derived from the receiver signal comes. A value of the property of the paint preparation assigned to this predetermined comparison parameter or comparison parameter value is then determined as a property of the paint formulation.

It is preferably provided that the receiver signal and / or the at least one derived measured variable is / are compared with a plurality of comparison parameter values of the at least one comparison parameter, a predetermined property value of the at least one property of the paint preparation being associated with each comparison parameter value or each combination of comparison parameter values. This type of process control is particularly accurate and also has the advantage that the process can be adapted by a person skilled in the art to individual peculiarities of the present invention the electrocoating system, in particular by a calibration.

According to one embodiment of the invention, it is provided that a solids content and / or a binder / pigment ratio of the paint formulation is determined as the at least one property of the paint formulation. This has the particular advantage that the two sensors and / or the manual sampling required hitherto can be dispensed with.

In a preferred embodiment it is provided that the paint preparation - preferably continuously - is conveyed through the waveguide. The determination of the at least one property of the paint formulation in a waveguide, wherein the paint formulation preferably originates from a particularly optimally thoroughly mixed region of the electrodeposition bath, has the advantage that a determination of the property in a dead zone of the electrodeposition bath is avoided, with dead zone an electrocoating bath is meant a volume element within the bath which is not optimally mixed, and thus the properties of the lacquer preparation determined therein do not apply to the entire electrodeposition bath. Moreover, continuous delivery through the waveguide has the advantage that the at least one property can be continuously monitored, in particular, permanently during operation of the electrodeposition bath.

According to one embodiment of the invention, it is provided that the paint preparation is conveyed in a sidestream to an electrodeposition bath, in particular during operation of the electrocoating bath, through the waveguide. This also has the advantage that the paint preparation can be removed in a very targeted manner from an optimally mixed point of the electrodeposition bath and supplied to the waveguide for further analysis. It is thus ensured that a value is always obtained for the entire electrocoating bath.

Furthermore, it is preferably provided that at least one metering device for metering at least one constituent of the electrodeposition bath into the electrodeposition bath is activated in dependence on the at least one specific property of the paint formulation such that a content of the at least one constituent in the electrodeposition bath is changed in the desired manner or kept constant. This has the advantage that the determined values are automatically transmitted to a (re) metering device and thus also the (re) metering can be carried out completely automatically. This shortens in a special way the time between the determination of the property and the (re) dosing, which is why the period in which the actual value deviates from the desired value can be kept particularly low. In addition, any manual activities are also eliminated in connection with (re) dosing.

Furthermore, the object is achieved in particular by providing an electrodeposition coating device which has an electrodeposition bath in which a paint preparation is arranged, in addition a secondary flow path, along which the paint preparation out of the electrodeposition bath and back into the electrodeposition bath in Side stream can be conveyed to the electrocoating bath. The electrocoating device has an acoustic waveguide arranged in the secondary current path with an acoustic transmitter arranged on the waveguide and an acoustic receiver arranged on the waveguide, and a control device connected at least to the acoustic receiver which is set up for carrying out a method or a method according to the invention one of the previously described embodiments. In connection with the electrocoating device, the advantages which have already been explained in connection with the method are realized in particular.

In a preferred exemplary embodiment, a metering device is provided for metering at least one constituent of the electrodeposition bath into the electrodeposition bath, wherein the control device is operatively connected to the metering device and designed to control the metering device as a function of the at least one specific property of the paint preparation in that a content of the at least one constituent in the electrodeposition bath is desirably changed or kept constant. This has the advantage that the system can be operated automatically, without any further intervention by a person.

Furthermore, it is preferably provided that downstream of the waveguide in the secondary flow path, a throttle device for throttling a flow of the paint preparation along the Nebenstrompfads is arranged. This has the advantage that disturbing gas bubbles or pressure fluctuations during the measurement can be avoided by increasing the pressure in the paint preparation in the side stream.

The throttle device is preferably designed as a throttle valve, as an adjustable diaphragm or in another way as with respect to a passage cross section variable throttle. But it is also possible that the throttle device is designed as a constant throttle, for example as a rigid diaphragm.

The invention will be explained in more detail below with reference to the drawing. The single figure shows an embodiment of an electrodeposition coating device with a control device.

The single FIGURE shows an embodiment of an electrodeposition coating device 1 with a control device 2 and an electrodeposition bath 3 with a paint preparation contained therein 4 , The waveguide 5 is in the figure in a Nebenstrom path 6 or in a bypass of the electrocoating bath 3 arranged.

On the waveguide 5 are a transmitter 7 for acoustic signals as well as a receiver 8th for acoustic signals on opposite sides of the waveguide 5 arranged. Inside the waveguide 5 are acoustic waves 9 represented as surface waves from the transmitter 7 be generated and along the waveguide 5 run, as well as partially in the paint preparation 4 be coupled out and as multi-reflected volume sound waves between opposite walls or wall sections of the waveguide 5 running back and forth, with the acoustic waves 9 , starting from the transmitter 7 , in the direction of the receiver 8th to run. By receiving the acoustic waves 9 at the receiver 8th and forwarding the corresponding information to the control device 2 is preferably via a calculation of the density, the speed of sound, the acoustic impedance and / or the transmission of at least one property of the paint preparation 4 , in particular the solids content and the binder / pigment ratio, in the control device 2 determined, wherein the determination is carried out via a comparison of the receiver signal and / or the values calculated therefrom with comparison values.

Furthermore, in the figure, a metering device 10 with two dosing valves 11 . 12 shown which with the control device 2 are actively connected. Furthermore, the metering valves 11 . 12 by fluid lines fluidly with the electrocoating bath 3 on the one hand and on the other hand each with a storage tank 13 . 14 in particular for a binder and at least one pigment. This has the particular advantage that in the control device 2 certain values for the solids content and the binder / pigment ratio as actual values with continue in the control device 2 deposited target values can be compared and thus an advantageous, fully automatic (re) dosing by means of the metering valves 11 . 12 can take place so that then the newly determined values for the solids content and the binder / pigment ratio as actual values with the target values are substantially the same. In particular, the calculation and control of the metering device 10 very fast, especially every second, by the controller 2 takes place, have the actual values of the paint preparation 4 Over time, there are no large deviations from the target values.

Furthermore, in the figure downstream in the secondary flow path 6 a throttle valve 15 shown. This leads to a substantially gas bubble-free paint preparation 4 in the waveguide 5 , And pressure fluctuations are thereby avoided.

Optionally, in the secondary flow path 6 a conveyor for in particular continuous promotion of the paint preparation through the secondary flow path 6 be arranged. This has especially for very viscous paint preparations 4 the advantage that the flushing of the secondary flow path 6 is actively operated.

In the context of the method, the receiver signal and / or at least one measured quantity derived therefrom is preferably compared with a plurality of comparison parameter values of the at least one comparison parameter, wherein each comparison parameter value or each combination of comparison parameter values has a predetermined property value of the at least one property of the paint preparation 4 assigned.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2008/034878 A2 [0007]

Claims (10)

Method for operating an electrodeposition coating device (1) and for determining at least one property of a paint preparation (4) for an electrodeposition coating, comprising the following steps: Arranging a part of the paint preparation (4) in an acoustic waveguide (5); - generating surface acoustic waves (9) in the waveguide (5) by means of a transmitter (7); - Receiving acoustic waves (9) on the waveguide (5) by means of a receiver (8) and receiving a receiver signal; Comparing the receiver signal and / or at least one measured variable derived from the receiver signal with at least one predetermined comparison parameter, and obtaining a comparison result, and - Determining the at least one property of the paint preparation (4) based on the comparison result. Method according to Claim 1 , characterized in that derived from the receiver signal as the at least one derived measure a physical quantity of the paint preparation (4) selected from a group consisting of an acoustic density, a sound velocity, an acoustic impedance, and a transmission. Method according to Claim 1 or 2 characterized in that the receiver signal and / or the at least one derived measured variable is / are compared to a plurality of comparison parameter values of the at least one comparison parameter, each predetermined parameter value or each combination of comparison parameter values being associated with the at least one property of the paint preparation (4) is. Method according to one of the preceding claims, characterized in that as the at least one property of the paint preparation (4) a solids content and / or a binder / pigment ratio of the paint formulation (4) is determined. Method according to one of the preceding claims, characterized in that the paint preparation (4) - preferably continuously - through the waveguide (5) is promoted. Method according to one of the preceding claims, characterized in that the paint preparation (5) in the secondary stream (6) to an electrocoating bath (3), in particular during operation of the electrocoating bath (3), through the waveguide (5) is promoted. Method according to one of the preceding claims, characterized in that at least one metering device (10) for metering at least one component of the electrocoating bath (3) into the electrodeposition bath (3) in dependence on the at least one specific property of the lacquer preparation (4 ) is controlled so that a content of the at least one component in the electrodeposition bath (3) is desirably changed or kept constant. Electrocoating apparatus (1), comprising - an electrodeposition bath (3) in which a paint preparation (4) is arranged; - a Nebenstrompfad (6), along which the paint preparation (3) from the electrodeposition bath (3) out and back into the electrocoating bath in the secondary flow to the electrocoating bath (3) is conveyed, characterized by - in the Nebenstrompfad (6) arranged acoustic waveguide (5) with an on the waveguide (5) arranged acoustic transmitter (7) and on the waveguide (5) arranged acoustic receiver (8), and - at least with the acoustic receiver (8 ) connected control device (2) which is adapted to carry out a method according to one of Claims 1 to 7 , Electrocoating device (1) according to Claim 8 characterized by a metering device (10) for metering at least one constituent of the electrocoating bath (3) into the electrodeposition bath (3), the control device (2) being operatively connected to the metering device (10) and configured to form the metering device (10) in response to the at least one specific property of the paint formulation (4) to control so that a content of the at least one component in the electrodeposition bath (3) is changed as desired or kept constant. Electrocoating device (1) according to Claim 8 or 9 , characterized in that downstream of the waveguide (5) in the secondary flow path (6) is arranged a throttle device (15) for throttling a flow of the paint preparation (4) along the secondary flow path (6).

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