JPH0454500B2 - - Google Patents

Description

Claim 1: Applying a first paint to at least a portion of the object to be painted, and then applying one or more paints of different colors, including at least a second paint, to other preselected portions of the object to be painted, In these methods of applying paint by baking hardening the paint coating, without subjecting the first paint to an intermediate baking process, a spray gap provided at the acute edge of a fixed atomizer edge with a wedge-shaped cross section is applied. electrostatically displacing paint particles by electrostatic spraying to apply one or more paints, including at least a second paint, to other preselected portions of the object to be coated, and applying the first paint and subsequent paints; Application of paints of two or more colors, characterized in that all paint coatings are baked together and cured after completion, and that the scattering behavior in the electrostatic field of the paint ejected from the fixed atomizer edge is regulated by auxiliary electrodes. Method.

2. The method for applying two or more colors of paint according to claim 1, characterized in that the electrostatic field is changed by moving an auxiliary electrode during spraying.

3. After applying the first paint to at least a portion of the workpiece using spray distributors arranged sequentially in the working direction, applying one or more paints of different colors, including at least a second paint, to the rest of the workpiece. Apparatus for carrying out a coating method in which paint coatings are applied to parts of the paint and hardened by baking, the final spray distributor 1 comprising at least a fixed atomizer edge for electrostatic atomization of paint particles, said fixed atomizer The edge has a wedge-shaped cross section, and the edge of the acute part has a
A narrow spray gap 9 is formed for the passage of the paint, and the motion of the object to be coated is such that the longitudinal axis X--X moves across the spray gap in the direction normal to the surface at the intercolor boundary. and a plurality of auxiliary electrodes 5 are disposed between the spray gap 9 and the object to be coated 2 and are movable. , Coating equipment for two or more colors of paint.

4. The coating device for two or more colors of paint according to claim 3, wherein the auxiliary electrode 5 is movable during spraying.

Description The present invention relates to a method for applying two or more colors of paint as defined in the preamble of the main claim.

The invention further relates to an apparatus for carrying out this method.

Conventionally, the method of applying two or more colors of paint by making the divisions between each color clear so that the individual paints do not cover all parts of the object is to first apply the first color to the object. After drying and baking this paint coating, a method is used in which the painted areas of this color are covered, and then a second paint or an additional paint is applied to the uncovered areas ( “Lehrbuch fu″r Fahrzeuglackierer [Vehicle painting instruction manual]”, Neuer Merkur
Published by GmbH Munich, first edition, 1981, p. 190). This method has the drawback of requiring a drying and baking step between the steps of applying the two types of paint, which is time consuming and energy consuming. Furthermore, there is the disadvantage that a large amount of paint is wasted in the overlapping areas.

In contrast, the present invention has relatively clear divisions between the painted parts of all different colors, satisfies the decorative requirements of the painted surface without the need for intermediate drying and baking processes, and It is an object of the present invention to provide a multi-color coating method and apparatus that can minimize the overlapping area at the boundary between the two colors.

This object is achieved by the method described in the characterizing part of the main claim.

According to the method proposed by the invention, a first paint, ie a color, is applied to the object to be coated in a known manner, for example by spraying in an electrostatic field using a pneumatic atomizer or a centrifugal atomizer. Then, without immediately drying or baking the first paint coating thus formed, the paint particles are moved electrostatically, and at the intercolor boundaries, paint droplets are applied to the surface of the object to be painted at the intercolor boundaries. A second paint of a generally different color and an additional paint of a generally different color are applied using an atomizer adapted to deposit in pulses substantially parallel to the vertical normal. The atomizer used in the present invention is configured to electrostatically move paint particles by electrostatic spraying from a spray gap provided at an acute edge of a stationary atomizer edge having a wedge-shaped cross section, and to generate a plurality of paint particles containing at least a second paint. This is a device that applies the paint to parts other than the parts coated with the first paint.

The method of moving paint particles using an electrostatic field by electrostatic spraying using a fixed atomizer edge is known for a long time (Industrielackierbetrieb, Vol. 25,
No. 2, 1957 pp. 34 and 35). This document states regarding the method that the spray pattern obtained is intermediate in shape between rectangular and oval, without sharp edges.

Claim 2 shows yet another aspect, in which the spray pattern can be changed even during spraying.

Claim 3 describes an apparatus for carrying out the method of the invention. The basic feature of this device is that the longitudinal axis of the atomizer gap formed by the atomizer edge is substantially perpendicular to the plane formed by the surface normal at the intercolor boundary and the direction of movement of the workpiece. and that a plurality of auxiliary electrodes are disposed between the spray gap and the object to be coated, and that they are movable. The effect of this configuration of the spray distributor is that the paint droplets at the boundary between colors are acted upon by an electrostatic force that is oriented parallel to the normal to the surface of the object to be coated at that location. A clear distinction between applied paints can be obtained at the color boundary.

A further preferred embodiment of the device according to the invention as defined in claim 4 provides that an auxiliary electrode is arranged in front of the atomizing gap in the atomizing gap, which is adjustable, preferably automatically adjustable, and limits the effective length of the atomizing gap. It is arranged in the axial direction. These auxiliary electrodes make it possible to adjust the width of the coating strip of paint, and by moving the auxiliary electrodes up and down during the painting process, it is very easy to contour the coating strip or to use other auxiliary means. It is possible to perform coating that adapts to the surface shape of the object to be coated without the need to use.

The present invention provides two different colored body shells for automobiles.
Particularly suitable for applying seed paints. That is, according to the present invention, it is possible to overcoat two colors of paint in an undried state. Furthermore, if the narrow boundary obtained by the method of the present invention is formed at the edge of a car door, for example, when the door is opened in a place where there is not enough space on both sides of the car, the edge of the door will be damaged. A band-like member to protect the
You can paste it on that part. The present invention eliminates intermediate steps previously required in painting operations, such as baking the first paint coat before applying the second paint coat. Therefore, the cycle time is shortened and the energy consumption per coated vehicle body shell is reduced. It also requires less space.

Hereinafter, one embodiment of the present invention will be described based on the drawings. In the drawings, Figure 1 is a schematic diagram of the spray distributor placed at an appropriate position with the object to be coated, and Figure 2 is an enlarged view of the relationship between the spray distributor and the object to be coated to clearly show the line of action. FIG. 3 is a perspective view showing the arrangement of the present invention.

In FIG. 1, numeral 1 is a spray distributor that operates at high pressure and transfers the supplied liquid paint to the spray gap 9.
Electrostatic spraying is possible from a fixed atomizer edge forming a (FIG. 3). An object 2 to be painted, for example a car body shell, is connected to earth and has a first paint coating 3 formed thereon. The second paint coat to be applied using the spray distributor 1, preferably having a different color, is indicated at 4.

A mechanically adjustable auxiliary electrode 5 can be arranged in front of the spray gap 9. This means that these auxiliary electrodes can, for example, be adjustable in the direction of the longitudinal axis X--X of the spray gap, thereby limiting the effective length of the spray gap 9.

In FIG. 3, the intercolor boundary is schematically indicated by 10, and 11 indicates the normal to the surface at the intercolor boundary.

The first coating 3 can be formed by a method conventionally used for coating objects to be coated.
There is no need for sharp separation of the first paint coating 3 with respect to the subsequently applied second paint coating 4, and conventional methods do not allow such a sharp separation to be achieved. As can be seen in particular from FIG. 1, the transition area of the first paint coating 3 may extend into the area to be applied with the second paint coating 4.

FIG. 2 shows the scattering trajectory of paint droplets under the influence of air resistance and gravity G. The relatively small, i.e. relatively light, paint droplets move along the scatter trajectory 7 towards the object to be coated, and the relatively heavy, i.e. large, paint droplets move from the spray distributor 1 to the object to be coated 2. It moves through a scattering trajectory 8. This dependence of the scattering trajectory on the size of the droplet results in the formation of transition areas for the second paint coating as well. However, the transition zone in this case is less than 2 cm wide, so that a sufficient delimitation between the two paint coatings 3, 4 is obtained. Also, since the width of the transition area is only 2 cm, as mentioned above, it can be covered with a suitable decorative strip or the like.

As can be seen from Figure 3, the clear color boundary 10
In order to obtain the longitudinal axis of the spray gap 9
must be arranged perpendicular to the plane formed by the surface normal 11 at the intercolor boundary.

As described above, in the present invention, the scattering behavior of the paint emitted from the fixed atomizer edge in the electrostatic field is regulated by the auxiliary electrode.
This has the effect of regulating the spray pattern.