DD285121A5 - METHOD FOR DIRECTING ENGAGEMENT OF FORM-COMPLICATED WORKSTOPS BY ELECTROSTATIC EMAIL POWDER COATING - Google Patents

Abstract

Method for direct enamelling of complicated workpieces by means of electrostatic enamel powder coating. The invention eliminates the disadvantages that otherwise arise in the direct enamelling when enamel powder is to be applied to form-complicated workpieces. The complicated workpieces or certain areas of these workpieces prevent the necessary structure of an electric field, as required for the electrostatic coating. This results in incorrect coatings, which then pose as enamelling. Gemaesz the invention, the critical areas of the form-complicated workpieces are initially with a multi-component suspension, z. As slip, coated without using an electric field and then applied the enamel powder on the entire workpiece. To reduce the surface tension of the enamel powder z. As an alcohol-water mixture or surfactants and / or foam regulator added to the slip. In addition, it is advantageous to use a slip which is strongly thixotropic. {Enamel coating; Powder coating; Electrostatics; Pulveremaillierung; Shape complexity; Cover enamel slip; Surface tension, lower; surfactants; Foam regulator; thixotropic slip}

Description

Field of application of the invention

The invention relates to a method for direct enamelling by means of electrostatic enamel powder coating preferably of form-complicated parts.

Characteristic of the known state of the art

It is known, using decarburized steel sheets to perform the enamel application as a direct enamelling by means of electrostatic powder coating (PUESTA method).

In general, werder. achieved good results. Thus, the PUESTA method is also recommended in the literature for use in highly complex parts (Petzold / Pöschmann, Verlag Grundstoffe [1986] p. 240).

A disadvantage occurs in that in the field of complicated shaping the enamel coating is insufficient and thereby creates a non-reworkable Committee.

This disadvantage also occurs in the application of electrostatic enamel powder coating in the 2-layer / 1-band process, where first the entire surface is coated with enamel or enamel enamel, in case 3 of the order of slip, this then dried and then the top enamel is electrostatically powdered.

The cause of the disadvantages mentioned is that in critical areas of the form-complicated workpieces, so-called.

Form Faraday cages, whereby the required for the powder coating J electric field is disturbed, or can not be built.

Object of the invention

The aim of the invention is to eliminate the aforementioned disadvantages and to achieve an optically and functionally adequate coating in the critical areas of the shape-complicated workpieces.

Essence of the invention

The object of the invention is to adequately coat the critical areas of mold-complicated workpieces in which Faraday cages are formed by measures independent of the electric field. According to the invention, the object is achieved in that first the critical areas of the shape-complicated workpieces with the multicomponent suspension, e.g. Slip, coated without the use of an electric field and then the enamel powder is electrostatically applied. The frit components of the slurry and the enamel powder are substantially similar. In order to reduce the surface tension, agents acting in accordance with the slip are added. As a suitable surface tension reducing agent, an alcohol-water mixture is used instead of water as the slurry for preparing the slurry. Depending on the surface tension and electrical resistance of the enamel powder to be used, the water content of the alcohol-water mixture is 4 ... 50%.

As the surface tension reducing agent, surfactants and / or foam regulators are also added to the slurry. The solution of the task is further, if a slurry is used with strong thixotropic properties.

embodiments

example 1

An overflow well of an electric fireplate is made of extruded, decarburized steel with a sheet thickness of 0.6mm. She goes through a Tauchbeizanlage in which degreasing, intensive pickling, nickel plating and neutralization are performed.

After this Oirektweißemaillierung (DWE) -Vt treatment, the overflow well by a continuous conveyor for Encouraged enamel coating plant. In a third cabin, a robot becomes a white slip with a programmable robot

injected to the upper and lower folds of the vertically suspended overflow trough. Then the trough goes through with one

Waste heat heated drying line. The titanium slurry, which is sprayed with a layer thickness of about 0.04-0.08 mm, is included

dried.

The part now passes through a powder application booth. In the electrostatic field at 4OkV by 4 on a mast

attached pistols titanium white powder veisprüht and knocked down on the part.

After powder application, the enamel is baked in a continuous oven. Afterwards the quality control takes place

the evenly enamelled part.

Example 2 A cover of a gas cooker with a double fold on the handle bar, which is difficult to enamel, is to be used in the DWE Process coated with enamel powder and enameled. For this purpose, the cover made of decarburized material is subjected to an appropriate pretreatment and on a Circular conveyor attached. The hood goes through the hanging on the circular conveyor a pre-cabin, in which a slip, consisting of a light gray in

the melt dyed enamel is injected behind the double fold of the handle bar.

The slurry had been prepared by using an alcohol-water mixture instead of water, the Ratio of alcohol to water was 60:40. After the thin spraying of this layer of about 40μιπ and a short drying it passes through the part Main spray booth and is coated with an enamel powder, which uses the same matrix as for the slip,

has been produced. After the hood has been pulverized, it is attached to the conveyor chain of an invert oven, fired and sorted.

Insufficient enamelling behind the double fold is not observed.

Claims (4)

1. A method for direct-enamelling of mold-complicated workpieces by means of electrostatic enamel powder coating, characterized in that first the critical areas of the form-complicated workpieces with a Mehrkomp.onentensuspension which are advantageously added the surface tension reducing agent coated without the use of an electric field and then the enamel powder is applied, wherein multicomponent suspension and enamel powder are substantially similar in their frit components, 2. Verfahien according to claim 1, characterized in that an alcohol-water mixture is used to prepare a multicomponent suspension, wherein the water content is 4 to 50%, depending on the powder quality used for use. 3. The method according to claim 1, characterized in that the multicomponent suspension surfactants and / or foam regulators be beigement. 4. The method according to claim 1 to 3, characterized in that a slurry having strong thixotropic properties is used as a multicomponent suspension.