US20110168548A1

US20110168548A1 - Device for the dip painting of a body part

Info

Publication number: US20110168548A1
Application number: US13/119,576
Authority: US
Inventors: Manfred A. Grimm
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2008-09-18
Filing date: 2009-09-09
Publication date: 2011-07-14
Also published as: EP2340323A1; RU2011114827A; DE102008047704B4; WO2010031516A1; DE102008047704A1; EP2340323B1

Abstract

A device for the dip painting of a body part with a basin for receiving a coating liquid has two parallel guides for guiding the body part and an anode body. The body part is connected to a cathode of a direct voltage source and the anode body to an anode of the direct voltage source. The anode body in position and spacing is assigned to the body part and guided through the basin with the body part. Because of this, adequate coating is ensured also in hollow spaces of the body part.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National-Stage entry under 35 U.S.C. §371 based on International Application No. PCT/EP2009/006553, filed Sep. 9, 2009, which was published under PCT Article 21(2) and which claims priority to German Application No. 102008047704.4, filed Sep. 18, 2008, which are all hereby incorporated in their entirety by reference.

TECHNICAL FIELD

The invention relates to a device for the dip painting of a body part of a motor vehicle with a basin for receiving a coating liquid, with a transport device for the transport of the body part through the basin, with a direct current source, with an anode body connected to the anode of the direct current source and with a guide connected to the cathode direct current source for the electrical contacting and moving of the body part through the basin.

BACKGROUND

Such devices are frequently employed for the dip painting of vehicle bodies such as individual body parts, for example a vehicle door or complete body shells and are for example known from DE 196 06 000 C1. With this device, several anode bodies are arranged in the basin and are supplied with electric current from various direct current sources. When guiding the body part through the basin a direct current field develops between the anodes and the surface of the body part. The body part attracts dispersion particles from the coating liquid. The coating liquid, which for example can be a watery dispersion of a baking enamel, is deposited as a layer on the body part.
In addition to the immersion time, the bath temperature and the composition of the coating liquid, the layer formation on the body part also depends on the strength and distribution of the electric direct current field. The layer thickness should amount to at least >=20 μm on the outside and >=10 μm within hollow spaces of the body part. The arrangement of fixed anodes however results in that on the outside of the body part a particularly thick layer and within the hollow spaces a particularly thin layer is deposited. This results in an undesirably large layer thickness on the outside and an undesirably small layer thickness within the hollow spaces of the body part.
To achieve as precise as possible a coating it is known from DE 103 26 605 A1 to arrange several anodes distributed over the basin and activate said anodes individually with a provided current/voltage characteristic curve corresponding to the contour of the body part. However, this results in a major control effort.
From JP 5 800 3996 (A) a device with a moveable anode body has become known. The anode body is laterally arranged next to the body part. With this device, too, only a small layer thickness can be deposited in regions of the body part that are distant from the anode body.
The invention is based on the problem of further developing a device of the type mentioned at the outset so that with it the layer thickness can be established at any point of the body part in as simple as possible a manner.

SUMMARY

According to an embodiment of the invention, this problem is solved in that the anode body can be mounted in a constant position to the body part in movement direction of the body part before and/or behind the body part and guided through the basin with the body part.
Through this configuration the anode body and the body part can be guided through the bath one after the other. This brings about a high and even field line density and with appropriate selection of the arrangement of the anode body guidable with the body part, a field strength penetration over the entire layer formation process on the regions of the body part, which are not or only inadequately reached with anode bodies that are locationally fixed or laterally moved along next to the body part. Through the position and alignment of the anode body with the body part the thickness and the distribution of the direct current field between the anode body and the body part can be largely freely determined. Since the strength and the distribution of the direct current field decisively influence the deposited layer thickness, the layer thickness thanks to the invention can be easily determined at any point of the body part. Thus, an undesirably high deposition on lateral regions of the body part can be avoided and an adequate deposition on hidden regions of the body part ensured at the same time. The device avoids a high control effort and can therefore be applied particularly easily. Obviously this device can be employed in an anodic method if the polarity of the direct current source with cathode bodies running along is reversed.
A preferred deposition of dispersion particles of the coating liquid in a hollow space of the body part can be achieved according to another advantageous further embodiment of the invention if the anode body that can be guided through the basin with the body part is arranged in front of an opening of a hollow space of the body part.
The device according to an embodiment of the invention is of a particularly simple construction if a further guide connected to the anode of the direct current source is provided and if the anode body that can be guided through the basin with the body part is guided on the further guide. Preferentially the guides are formed as current rails, from which the body part and the anode body are indirectly suspended.
It contributes to the further simplification of the design structure of the device if the two guides are arranged parallel to each other and each has a holding arm for holding the anode body guidable through the basin with the body part or of the body part. Through this configuration the guides can be arranged outside the basin. The holding arms thus constitute the connections of the guides arranged outside the basin to the anode bodies and the body part arranged within the basin.
A particularly uniform deposition of dispersion particles of the coating liquid on the body part can be easily achieved according to another advantageous further embodiment of the invention if the anode body guidable through the basin with the body part is designed elongated in shape. The elongated anode body is preferentially arranged parallel to likewise elongated body parts or in front of an elongated opening in the body part.
At various points of the body part, layer thicknesses provided according to another advantageous further embodiment of the invention can be created if several anode bodies guidable through the basin with the body part are grouped round about the body part. Preferentially an anode body guidable through the basin with the body part is mounted on both sides of the body part.
It is a contribution to the equalization of the deposited layer thicknesses according to another advantageous further embodiment of the invention if in the basin at least a further fixed anode body connected to the anode of the direct voltage source is arranged. Through this configuration, both the at least one anode body immovably arranged in the basin as well as the anode body or bodies guidable through the basin with the body part each form a direct current field with the body part. Thus, sudden differences of the layer thicknesses deposited on the body part are reliably avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and:

FIG. 1 is a schematic of a device according to an embodiment of the invention with a body part arranged therein; and

FIG. 2 is a sectional representation through a part region of the device according to the embodiment of the invention from FIG. 1 along the line II-II.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and is not intended to limit application and uses. Furthermore, there is no intention to be bound by any theory presented in the preceding background or summary or the following detailed description.
FIG. 1 schematically shows a device for the dip painting of a body part 1 formed as vehicle door of a motor vehicle. The device has a basin 2 for receiving a coating liquid 3 and the body part 1. In addition, several anode bodies 4 are arranged in the basin 2. The body part 1 is connected in an electrically conductive manner to a cathode (−) of a direct current source 7. The anode bodies 4-6 are connected to the anode (+) of the direct current source 7.
Two of the anode bodies 4, 5 are arranged in the basin 2 in a fixed manner, while one of the anode bodies 6 can be moveably guided through the basin 2 with the body part 1. The body part 1 and the anode body 6 guidable through the basin 2 with the body part 1 are each arranged on a holding arm 8, 9 and longitudinally displaceably guided in a guide 10, 11. The guiding direction is perpendicular to the drawing plane. Thus the body part and the anode body 6 guidable through the basin 2 with the body part 1 are arranged one after the other seen in movement direction. By way of electric motors 12, 13 the anode body 6 guidable through the basin 2 with the body part 1 and the body part 1 can be simultaneously moved out of the basin 2 and into the basin. Through simultaneous activation of the electric motor 12, 13 the spacing and the position of the anode body 6 guidable through the basin 2 with the body part 1 to the body part 1 is kept constant. The anode body 6 guidable through the basin 2 with the body part is elongated in shape and arranged parallel to the longest extension of the body part 1. The guide 10 for the body part 1 and the electric motor 12 connected thereto form a transport device for guiding the body part 1 through the basin 2.
In a part section through the device from FIG. 1 along the line II-II, FIG. 2 shows that altogether two anode bodies 6, 6′ guidable through the basin 2 with the body part 1 are arranged on both sides of the body part 1. The moveably guided anode bodies 6, 6′ are arranged near a hollow space 14 of the body part 1. The hollow space 14 of the body part 1 shown in the shown exemplary embodiment has an opening 15 facing one of the guided anode bodies 6.
While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

Claims

1. A device for dip painting of a body part of a motor vehicle, comprising:

a basin for receiving a coating liquid;

a transport device for transporting the body part through the basin;

a direct current source with an anode body connected to an anode of the direct current source; and

a guide connected to a cathode of the direct current source for electrically contacting and guiding of the body part through the basin,

wherein the anode body is configured for mounting in a substantially constant position with respect to the body part in a movement direction of the body part and guidable through the basin with the body part.

2. The device for the dip painting according to claim 1, further comprising a further guide connected to the anode of the direct current source and the anode body is guided on the further guide.

3. The device for the dip painting according to claim 1, wherein the guide and the further guide are arranged substantially parallel to each other and in each case comprise a holding arm configured to hold the anode body.

4. The device for the dip painting according to claim 1, wherein the anode body has an elongated shape.

5. The device for the dip painting according to claim 1, further comprising several anode bodies guidable through the basin with the body part are grouped about the body part.

6. The device for the dip painting according to claim 1, further comprising at least one further fixed anode body in the basin connected to the anode body of the direct voltage source.

7. The device for the dip painting according to claim 1, wherein the guide and the further guide are arranged substantially parallel to each other and in each case comprise a holding arm configured to hold the body part.