EP1749903B1 - Electrophoretic lacquering plant - Google Patents

Description

1. a) einem Lackbad;
2. b) einer Fördereinrichtung, mit der die zu lackierenden Werkstücke im Durchlaufverfahren in das Lackbad eingetaucht, durch dieses hindurchbewegt und wieder herausgehoben werden können;
3. c) mindestens zwei Spannungsquellen;
4. d) in dem Lackbad längs des Bewegungsweges der Werkstücke angeordneten Elektroden, die mit einem ersten Pol mindestens einer Spannungsquelle verbunden sind;
5. e) mindestens einer Kontaktschiene, die sich entlang des Bewegungsweges der Werkstücke erstreckt und mit einem zweiten Pol mindestens einer Spannungsquelle verbunden ist;
6. f) für jedes Werkstück eine Kontakteinrichtung, die mit mindestens einer Kontaktschiene in Verbindung steht und somit das Werkstück auf das Potential des zweiten Poles der mindestens einen Spannungsquelle legt.

The invention relates to an electro-dip painting with

1. a) a paint bath;
2. b) a conveyor, with which the workpieces to be painted in a continuous process immersed in the paint bath, moved therethrough and can be lifted out again;
3. c) at least two voltage sources;
4. d) in the paint bath along the path of movement of the workpieces arranged electrodes which are connected to a first pole of at least one voltage source;
5. e) at least one contact rail, which extends along the path of movement of the workpieces and is connected to a second pole of at least one voltage source;
6. f) for each workpiece, a contact device which is in communication with at least one contact rail and thus sets the workpiece to the potential of the second pole of the at least one voltage source.

In electro-dip painting, also called electrophoretic painting, the paint components separate in the Lackbad under the influence of an electric field on the workpieces. It has proven to be expedient not to keep the electric field during the passage of the workpieces through the coating bath constant, but to vary along the path of movement, in particular to let rise with the distance traveled. Reason for this measure is, inter alia, that the build-up paint layer is an electrical resistance, which complicates the further construction of the paint layer.

This raises the problem of how, for each workpiece, the stress on passage through the paint bath can be changed. In electro-dip painting devices of the type mentioned, as z. B. in the DE 199 42 556 C2 are described, the power supply to the workpiece via a in the direction of movement of the workpieces to be painted divided into sections contact rail; the sections are galvanically isolated and connected to one pole of a voltage source associated with each section. The electrodes arranged along the path of movement of the workpieces in the paint bath are connected to the other pole of the voltage sources. The disadvantage here is that it is relatively difficult to control technology to track the path of each workpiece along the various sections of the contact rail and to accomplish the transition of the workpiece from one section to the other section without "jump" in the potential. Since the charge flowed between the electrode and the workpiece is used as a measure of the applied layer thickness, it is also necessary to "join in" the measurement of the current flowing to the workpiece in sections with the movement of the workpiece. Finally, the "cuts" in the contact rails, which cause the galvanic separation, Also unevenness in the contact rail, which lead to wear of mitbewegten with the workpieces contact devices.

When changing the workpiece type, z. As the length of the workpiece, or when changing the immersion curve, the positions of the cuts between the contact rail sections, so that a system change is required for optimum coating.

Object of the present invention is to provide an electro-dip painting device of the type mentioned in such a way that it can be easily controlled and causes less wear on the contactors.

1. g) mehrere Kontaktschienen vorgesehen sind, die sich ohne elektrische Unterbrechung parallel zueinander entlang des gesamten durch das Lackbad führenden Bewegungsweges der Werkstücke erstrecken und jeweils mit dem zweiten Pol unterschiedlicher Spannungsquellen verbunden sind.

This object is achieved in that

1. g) a plurality of contact rails are provided, which extend without electrical interruption parallel to each other along the entire path leading through the paint path of the workpieces and are each connected to the second pole of different voltage sources.

According to the invention, at least as many contact rails are provided, as at the same time workpieces are to be in the paint bath. Then, each workpiece can be assigned a single contact rail whose potential can be varied during the passage of the workpieces through the coating bath to its full length, without thereby changing the voltage applied to the other workpieces. In this way, the annoying "cuts" are avoided in the contact rails, on the one hand to the increased control effort and on the other hand to the undesirable Wear in the art led. The invention allows a more individual adaptation of the voltage guide along the path of movement to the individual workpiece. As a result, the layer thicknesses can be maintained more accurately, which leads to paint savings:

According to a particularly preferred embodiment of the invention, the contact device comprises a contact shoe and is arranged so that the contact shoe can be brought into different, the plurality of contact rails corresponding layers. In this case, it can therefore be redetermined by determining the position of the contact shoe for each workpiece, which of the several parallel to each other, e.g. superimposed contact rails for this workpiece "in charge" is. The displacement of the contact shoe takes place under the influence of the central system control.

In this case, the contact device may have a fluid-actuated cylinder or an electrically actuated actuator, with which the contact shoe can be moved.

Preferably, the contact device has a latching device, with which the contact shoe can be releasably locked in different positions. This facilitates the finding of the correct position for the contact shoe as well as the maintenance of this altitude during the movement of the workpiece along the associated contact rail.

The fluid actuated cylinder or the electrically actuated actuator may optionally be movable or stationary together with the workpiece.

Also favorable is a soft-type guide device with a convertible guide member, with which a contact shoe can be passed during its movement either on one of the various contact rails.

Particularly flexible is that embodiment of the invention in which each workpiece for each contact rail a bewegbarer along the respective contact rail contact shoe zugeodnet and in which an electrical switch is provided for each workpiece, with which the various contact shoes associated with the workpiece optionally be switched through to the workpiece can.

Figur 1

schematisch eine erste Art der Kontaktierung von Fahrzeugkarosserien in einem Elektro-Tauchlackierbad;

Figur 2

ebenfalls schematisch ein erstes Ausführungsbeispiel einer verstellbaren Kontakteinrichtung, die jede Fahrzeugkarosserie in Figur 1 besitzt:

Figur 3

ähnlich der Figur 2 ein zweites Ausführungsbeispiel einer verstellbaren Kontakteinrichtung;

Figur 4

ähnlich der Figur 1 eine zweite Art der Kontaktierung von Fahrzeugkarosserien;

Figur 5

ähnlich der Figur 1 eine dritte Art der Kontaktierung von Fahrzeugkarosserien.

Embodiments of the invention will be explained in more detail with reference to the drawing; show it

FIG. 1

schematically a first way of contacting vehicle bodies in an electro-dip bath;

FIG. 2

also schematically a first embodiment of an adjustable contact device, each vehicle body in FIG. 1 has:

FIG. 3

similar to the FIG. 2 a second embodiment of an adjustable contact device;

FIG. 4

similar to the FIG. 1 a second way of contacting vehicle bodies;

FIG. 5

similar to the FIG. 1 a third way of contacting vehicle bodies.

First, it will open FIG. 1 Referenced. This shows a total of three vehicle bodies 1a, 1b, 1c, the one can think of immersed in a paint-filled paint pool, as mentioned in the above DE 199 42 556 C2 is described. The paint pool is in FIG. 1 not shown, as well as the conveyor, with which the various vehicle bodies 1 are moved continuously or intermittently through the paint pool. In question comes, for example, a suspension conveyor, as he as a conveyor 12 in the DE 199 42 56 C2 is shown, but also a conveyor that makes use of individual, independently movable and controllable weighing.

In the paint pool, not shown, counter electrodes, in particular anodes, placed in a known manner along the path of movement of the vehicle bodies 1a, 1b, 1c, as is also the DE 199 42 556 C2 can be seen. In the electric field, which is established within the paint liquid between the counter electrodes and the vehicle bodies 1a, 1b, 1c, the deposition of the paint components on the vehicle bodies 1a, 1b, 1c takes place. The ampere-hour number that has flowed between the counterelectrodes and the vehicle bodies 1a, 1b, 1c as they pass through the paint pool represents a direct measure of the thickness of the deposited paint layer.

In order to produce the required for the electrophoretic deposition of the paint electric field, the vehicle bodies 1a, 1b, 1c must be connected during their movement through the paint bath to the corresponding pole of a DC voltage source, in the usual case of cataphoretic dip painting with the negative pole.

This contacting happens in the following way:

Along the leading through the paint pool movement path of the vehicle bodies 1a, 1b, 1c, but outside the paint liquid, extend as many contact rails 2a, 2b, 2c, as at most vehicle bodies 1a, 1b, 1c are present in the paint bath simultaneously. In the present case, there are therefore three contact rails 2a, 2b, 2c. These contact rails 2a, 2b, 2c are not interrupted along their entire length, and thus do not have the "cuts" that are customary in the prior art, ie points at which various sections of the contact rails 2a, 2b, 2c are joined to one another in an electrically insulated manner. Each contact rail 2a, 2b, 2c is connected to a pole, preferably the negative pole, of its own controllable DC voltage source 20a, 20b, 20c. The other pole of these DC voltage sources 20a, 20b, 20c is connected to the electrodes arranged along the path of movement, preferably anodes.

The assignment of the vehicle bodies 1a, 1b, 1c to the corresponding contact rails 2a, 2b, 2c and thus to the corresponding DC voltage sources 20a, 20b, 20c takes place in that the contact rails 2a, 2b, 2c at different heights along the path of movement of the vehicle bodies 1a , 1b, 1c extend. At the in FIG. 1 illustrated embodiment, the contact rail 2a is highest, the contact rail 2c at the lowest and the contact rail 2b between the contact rails 2a and 2c. In this way, it is possible along the entire length of each contact rail 2 a, 2 b, 2 c in each case to move a contact shoe 3 a, 3 b, 3 c, which is electrically and mechanically connected to the respective vehicle body 1 a, 1 b, 1 c.

Due to the described arrangement, it is possible to Voltage, which is applied to the vehicle bodies 1a, 1b, 1c, set individually and to change their path of movement within the paint basin, without affecting the respective other vehicle bodies 1a, 1b, 1c, which are located within the paint basin. The application of voltage pulses within certain sections of the movement path to individual vehicle bodies 1a, 1b, 1c is also possible.

Due to the lack of contact rail sections, which are always associated with mechanical irregularities, the wear on the contact shoes 3a, 3b, 3c is smaller than was the case in the prior art. By eliminating the individual, separated by "sections" sections of the contact rail also designed the controller easier.

At the path of movement of the vehicle bodies 1a, 1b, 1c before entering the paint bath is a contact adjusting device, which is generally designated by the reference numeral 4 and schematically in FIG. 2 is shown. This contact adjusting device 4 serves to bring the corresponding contact shoe 3a, 3b, 3c to the correct height for each vehicle body 1a, 1b, 1c entering the paint bath so that the correct contact rail 2a, 2b, 2c touches on the further path becomes.

In FIG. 2 showing a section perpendicular to the direction of movement of the vehicle bodies 1a, 1b, 1c, the contact bars are again denoted by the reference numerals 2a, 2b, 2c; they are attached to any stationary support structure 5. At a distance from the support structure 5 and the attached contact rails 2a, 2b, 2c, an element 6 of the conveyor moves past, which is associated with one of the vehicle bodies 1a, 1b, 1c. For example, it can be an element of an overhead trolley or a self-propelled trolley carrying the vehicle body 1a, 1b, 1c.

On a vertical side surface of the element 6, a plate 7 is fixed, which in turn on its side facing away from the element 6 vertical three cross-sectionally V-shaped grooves 8a, 8b, 8c has. Instead of grooves and conical depressions may be provided.

As FIG. 2 shows extends between one of the grooves 8a, 8b, 8c, in the present case the groove 8a, and one of the contact rails 2a, 2b, 2c, in the present case the contact rail 2a, belonging to the vehicle body 1a contact shoe 3a. This is an essentially cylindrical part, which carries the actual contact 9 on its spherical cap-shaped rounded end face facing the contact rail 2a. At least its outermost layer is made of electrically conductive carbon.

The plate 7 and thus the groove 8a facing end portion of the contact shoe 3a is provided with a blind bore 10 into which a detent ball 11 can be more or less pushed. The detent ball 11 is pressed by a tensioned between her and the bottom of the blind bore 10 compression spring 14 into the groove 8a. The entire contact shoe 3a can be adjusted in the direction of the double arrow 13 with the aid of a pneumatic cylinder 12 or another actuator, which is moved along with the vehicle body 1a on the conveyor 6.

The contact adjusting device 4 described works as follows:

At the beginning of the path of movement of each vehicle body 1 a, 1 b, 1 c through the paint pool or even before entering this path of motion, the controller, under which the entire electro-dip painting works, assigns the respective vehicle body 1 a, 1 b, 1 c a contact rail 2 a, 2 b, 2c, over which the vehicle body in question 1a, 1b, 1c is brought to the corresponding voltage during the Lackabscheidevorganges. The pneumatic cylinder 12 is now addressed by the controller so that it brings the contact shoe 3a, 3b, 3c of the corresponding vehicle body 1a, 1b, 1c to the correct height, in which the conductive contact 9 in abutment against the corresponding contact rail 2a, 2b, 2c is. The finding and maintaining the correct height is facilitated by the locking device, which is formed by the grooves 8a, 8b, 8c and the detent ball 11 of the contact shoe 3a.

Now, the respective vehicle body 1 a, 1 b, 1 c are guided through the paint pool, with a possibly time-varying voltage on the vehicle body 1 a, 1 b, 1 c applied. The control of the forming paint layer thickness on the flowed charge is very easy, since only a single, flowed through a contact rail 2a, 2b, 2c current without section-wise switching needs to be measured.

In FIG. 3 another embodiment of a contact adjusting device 104 is shown, the above with reference to the FIG. 2 described very similar. Corresponding parts are therefore in FIG. 3 with the same reference numerals as in FIG. 2 , plus 100, marked.

The most important difference between the two contact adjusting devices 4, and 104 is that in those of FIG. 3 the pneumatic cylinder 112 is not connected to the conveyor 106 but rigidly connected to an element 105 of the stationary support structure, so even stationary. At the end of the piston rod 115 of the pneumatic cylinder 112 is a side, in FIG. 3 opposite to the viewing direction forward, open fork 116, which can engage around the contact shoe 103a for vertical displacement. Once the displacement has taken place, the contact shoe 103a can move forward as the vehicle body 101a moves out of the fork 116 FIG. 3 drive out to the front.

At the in FIG. 1 illustrated and described above type of contacting the various vehicle bodies 1a, 1b, 1c was the assignment of the individual vehicle bodies 1a, 1b, 1c to the individual contact rails 2a, 2b, 2c by the mechanical working contact adjusting device 4 and 104 after FIG. 2 or FIG. 3 , This mechanical switching is in the embodiment after FIG. 4 replaced by an electrical one.

In FIG. 4 wear parts, those of the FIG. 1 200, to the extent that they are unchanged in their function, will not be discussed again below.

Each vehicle body 201a, 201b, 201c in FIG FIG. 4 is associated with an electrically controllable switch 204a, 204b, 204c, which is moved with the vehicle body in question 201a, 201b, 201c. Each vehicle body 201a, 201b, 201c also includes three contact shoes 203aa, 203ab, 203ac, 203ba, 203bb, 203bc, 203ca, 203cb, 203bb, which together with the vehicle body 201a, 201b, 201c each extend along one of the three contact rails 202a, 202b, 202c can be moved. These contact shoes 203 can be selectively switched through by the respective changeover switch 2004a, 204b, 204c in response to a control command to the respective vehicle body 201a, 201b, 201c.

Another example of how the individual workpieces can be assigned to specific contact rails shows FIG. 5 , In this are parts that are such FIG. 1 are denoted by the same reference numerals plus 300. The basic structure in FIG. 5 with the plurality of contact rails 302a, 302b, 302c, the contact shoes 303a, 303b, 303c sliding thereon and the DC power sources 320a, 320b, 330c is the same as in FIG FIG. 1 ,

In the direction of movement of the vehicle bodies 301a, 301b, 301c in front of the contact rails 302a, 302b, 302c is one of the switching means 4 and 104 of the Figures 2 and 3 replacing soft-type guide device 304 is provided. This has a drogue 304a, in which the contact shoes 303a, 303b, 303c of all approaching vehicle bodies 301a, 301b, 301c are introduced regardless of their altitude in their movement. The contact shoes 303a, 303b, 303c, which are guided vertically movably on the conveyor, are all brought to the same height position in the drogue 304a and reach a guide member 304b. This can be pivoted under the commands of the system control so that its outlet is optional in the amount of the contact rail 302a, 302b or 302c. In this way, each contact shoe 303a, 303b, 303c automatically runs on the contact rail 302a, 302b, 302c intended for it.

Claims (9)

1. An electro-dipcoating apparatus with

   a) a lacquer bath;

   b) a conveying device by which the workpieces to be lacquered can be dipped into the lacquer bath, moved through the latter, and lifted out again in a continuous process;

   c) at least two voltage sources;

   d) electrodes arranged in the lacquer bath along the path of motion of the workpieces, which are connected to a first pole of at least one voltage source;

   e) at least one contact rail which extends along the path of motion of the workpieces and is connected to a second pole of at least one voltage source;

   f) for each workpiece, a contact device which is connected to a single contact rail and which consequently applies the potential of the second pole of the at least one voltage source to the workpiece,

   g) several contact rails (2a, 2b, 2c; 202a, 202b, 202c; 302a, 302b, 302c) which extend parallel to one another without electrical interruption along the entire path of motion of the workpieces (1a, 1b, 1c; 201a, 201b, 201c; 301a, 301b, 301c) leading through the lacquer bath and which are each connected to the second pole of varying voltage sources (20a, 20b, 20c; 220a, 220b, 220c; 320a, 320b, 320c).
2. Electro-dipcoating apparatus according to Claim 1, characterised in that the contact device comprises a contact shoe (3a, 3b, 3c; 103a, 103b, 103c) and is arranged in such a way that the contact shoe (3a, 3b, 3c; 103a, 103b, 103c) can be brought into various positions corresponding to the several contact rails (2a, 2b, 2c; 202a, 202b, 202c).
3. Electro-dipcoating apparatus according to Claim 2, characterised in that the contact device exhibits a fluid-operated cylinder (12; 112) by which the contact shoe (3a, 3b, 3c; 103a, 103b, 103c) can be displaced.
4. Electro-dipcoating apparatus according to Claim 2, characterised in that the contact device exhibits an electrically operated actuator by which the contact shoe can be displaced.
5. Electro-dipcoating apparatus according to one of Claims 2 to 4, characterised in that the contact device exhibits a latching device (8a, 8b, 8c, 11; 108a, 108b, 108c, 111) with which the contact shoe (3a, 3b, 3c; 103a, 103b, 103c) can be releasably locked in the various positions.
6. Electro-dipcoating apparatus according to one of Claims 2 to 5, characterised in that the fluid-operated cylinder (12) or the electrical actuator is capable of being moved concomitantly with the workpiece (1a, 1b, 1c).
7. Electro-dipcoating apparatus according to one of Claims 2 to 5, characterised in that the fluid-operated cylinder (112) or the electrical actuator is stationary.
8. Electro-dipcoating apparatus according to Claim 1, characterised in that for each contact rail (202a, 202b, 202c) a contact shoe (203aa, 203ab, 203ac, 203ba, 203bb, 203bc, 203ca, 203cb, 203cc) that is capable of being moved along the respective contact rail (202a, 202b, 202c) is assigned to each workpiece (201a, 201b, 201c) and in that for each workpiece (201a, 201b, 201c) an electrical change-over switch (204a, 204b, 204c) is provided, with which the various contact shoes (203aa, 203ab, 203ac, 203ba, 203bb, 203bc, 203ca, 203cb 203cc) assigned to the workpiece (201a, 201b, 201c) can optionally be switched through to the workpiece (201a, 201b, 201c).
9. Electro-dipcoating apparatus according to Claim 1, characterised by a points-type guiding device (304) with a relocatable guiding member (304b) with which a contact shoe (303a, 303b, 303c) can optionally be routed onto one of the various contact rails (302a, 302b, 302c) in the course of its motion.

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