EP3205407A1 - Method and installation for covering internal walls of a cavity with a protective layer made of corrosion protecting wax - Google Patents

Abstract

Proposed is a method for covering inner walls of a cavity (12) with a protective layer (50) of anti-corrosion wax, in particular for use on vehicle bodies (10) and attachments for vehicle bodies. In this case, corrosion protection wax by means of a mist generator (30) in atomized form (protective wax mist (40)) brought and fed through an outlet opening (32) to be preserved cavity (12). The protective wax mist (40) is deposited on inner walls of the cavity (12) and forms here a corrosion protection wax layer (50).

Description

AREA OF APPLICATION AND PRIOR ART

The invention relates to a method for covering inner walls of a cavity with a protective layer of anti-corrosion wax according to the preamble of claim 1, in particular for use on vehicle bodies and attachments for vehicle bodies.

The invention further relates to a system for carrying out the method according to the preamble of claim 1.

Generic methods are used in vehicle construction to protect body parts and in particular cavities of bodies and their attachments such as flaps, doors and the like against environmental influences. Typically, this is done by either applying corrosion protection wax to the surfaces concerned by spraying or by flooding the cavities with anticorrosion wax and then removing excess protective wax to cover the surfaces concerned.

Both methods are not ideal for every purpose. The spraying of corrosion protection wax does not allow complex geometries to reach all surfaces of the cavity starting from a point of exit of the protective wax. Beyond, for example, bulkhead plates that are subject to reinforcement, spray shadow areas may remain which are unreachable. Even narrow geometries such as intermediate areas of double-walled designs are difficult to achieve by spraying. Flooding with corrosion protection wax requires great energy and protective wax amounts and is complicated by the need to remove the excess protective wax. Furthermore, improvements in the cycle times in the application of anti-corrosion wax by means of floods are difficult to achieve.

TASK AND SOLUTION

The object of the invention is to provide a technically uncomplicated method and a system provided for this purpose, by means of which, with a low protective wax insert, a reliable covering of inner surfaces of a cavity is possible.

According to the invention, the following method is provided: Corrosion protection wax is brought into a misted form (protective wax mist) by means of a mist generator and fed through an outlet opening to the cavity to be preserved. The protective wax mist is deposited on the inner walls of the cavity and forms here a corrosion protection wax layer.

According to the invention, it is therefore provided that within the cavity a mist atmosphere of protective wax and gas is generated or such a mist atmosphere is supplied to the cavity. This consists of gas, especially air, as well as the finest droplets of corrosion protection wax. These are sufficiently small atomized to be hoverable in the surrounding air. The mean droplet size of the droplets of the corrosion protection wax in the mist is preferably <120 .mu.m, in particular preferably <80 .mu.m or even <60 .mu.m, on average for this purpose. The production of such a protective wax mist takes place by means of a suitable mist generator. This may for example be a one-fluid nozzle, which is supplied to the corrosion protection wax at high pressures. This will be explained in more detail later.

The fog atmosphere of the protective wax mist, which is introduced according to the invention for the purpose of surface coating in the cavity, unlike spraying the anti-corrosion wax does not directly on the walls of the cavity down, but spreads in the cavity and is also reflected in surfaces starting from the exit opening would not be directly accessible by spraying.

By deliberately heating or cooling the walls of the cavity, the type of precipitation of the protective wax and the layer formation can be influenced. Furthermore, it is also possible to influence the precipitate by electrostatic charging of the wax before or during the discharge and / or charge of the walls.

Depending on the nature of the protective wax, the solidification can be effected by an elevated temperature and a reduced temperature of the protective wax. Depending on the protective wax used, chemical drying, radiation drying or drying by air flow is also possible.

The protective wax mist can remain in the cavity at the completion of the process or be sucked out of it.

As corrosion protection wax to be used for cavity preservation in vehicles already commonly used for spraying or flooding waxes come into question. By way of example, the corrosion protection wax with the brand name Eftec Efcoat WH 320 A1 is mentioned, which can find use here.

The droplets of the protective wax mist can emerge from the outlet opening at a speed <5 m / sec, preferably 2 <m / sec, in particular preferably <0.5 m / sec.

Due to the comparatively slow exit of the protective wax mist from the outlet opening, the formation of a mist atmosphere is favored. Too high speeds can cause that, despite the small droplet size too large a proportion of the droplets hits directly on a flat wall of the cavity and thus can no longer contribute to the formation of a mist atmosphere.

However, it may be expedient to set the developing fog atmosphere in a targeted manner in motion. This can be controlled by the speed and exit direction of the exiting protective wax mist. The control of this movement by otherwise supplied energy is possible.

The supply of the protective wax mist can take place at several points or at changing points within the cavity to be preserved. The supply of the protective wax mist can also be effected by means of a plurality of mist generators, which are arranged at different locations within the cavity to be preserved and / or are arranged in different directions relative to the cavity to be preserved.

Even if in principle the introduction of the protective wax mist at only one point of the cavity can be sufficient, since the protective wax mist is distributed in the cavity, a particularly good and effective rapid distribution of the mist can be favored by the said additional measures. Through several outlet openings, which are arranged for example at opposite ends of an elongated cavity, the mist atmosphere can be created from both ends. By a movable within the cavity outlet opening which discharges at different locations, with only one outlet opening a fairly homogeneous mist atmosphere can be created. By means of a plurality of outlet openings, which point in different directions, it is particularly well ensured, in particular in conjunction with a common movement of these outlet openings through the cavity, that the mist atmosphere also reaches hard-to-reach surface areas.

By generating a pressure difference between two offending portions of the cavity, the protective wax mist can be moved within the cavity. In this case, by alternately generating an overpressure and a negative pressure in at least a partial area of the cavity, a periodically repeated movement of the protective mist in the cavity can be produced.

Although the protective wax mist is distributed basically independently in the cavity largely homogeneous. However, since short cycle times are desired depending on the application, it may be particularly advantageous to selectively move the protective wax mist through a local overpressure or negative pressure in the cavity. This can be done, for example, by the introduction or suction of air at an opening of the cavity, either by a separate from the outlet pressure opening of the cavity preservation system or through the outlet opening itself. By periodically repeated increases or decreases pressure can also cyclic movement of the protective wax mist be generated in the cavity through which a particularly favorable precipitation behavior of the protective wax is achieved on the surface.

A typical workpiece, which is protected against corrosion by the methods according to the invention, is the partial area of a body with an elongate cavity. In such a case, it is possible to allow the protective mist to escape through the outlet opening in alignment with the main extension direction of the cavity.

However, the protective mist can also escape in a direction out of the outlet opening, which is angled relative to the main extension direction of such a cavity.

By an angled discharge direction through the outlet opening can be achieved that the protective mist moves helically within the preferably elongated cavity, which favors the precipitation on all surfaces.

A similar effect can be achieved by providing an influence after exiting the mist through the outlet opening. The protective wax mist can be selectively influenced after leaving the outlet opening with regard to its direction of movement, in particular by supplying air from different air nozzles from the outlet opening. By their mutually angled orientation these air nozzles are also able to effect such a helical movement of the mist atmosphere.

However, other techniques are also possible to specifically influence the movement of the mist within the cavity. These include, for example, magnetism and electrostatics as useful principles of action.

To generate the mist, various techniques already known from the prior art can be used. Fog nozzles are already known from other areas of the prior art.

One possible concept is that a mixture of protective wax and air, which are each pressurized, takes place before the protective wax mist emerges. The pressurized air ruptures the liquid supplied protective wax and thereby generates the mist.

A contrast preferred embodiment provides that only the protective wax is pressurized and is atomized through a narrow Einstoffdüse therethrough. The supply of the protective wax is in this case preferably at a pressure of at least 20 bar, more preferably at least 60 bar. Of particular advantage are even higher pressures, in particular from about 100 bar. Although, by clearly exceeding this value, the nebulization can be positively influenced. Beyond 120 bar, however, the expense of handling the protective wax before discharge is so great that it should usually be disregarded.

Another possibility of mist generation provides a high-frequency oscillating actuator, such as a piezoelectric actuator or another form of ultrasonic atomizer.

For all forms of mist generators and outlet openings may additionally be provided that they have a rotatable component, so that the outlet openings is during the exit of the protective wax in a rotational movement, which serves the homogeneous distribution of the protective wax.

The outlet opening may be connected upstream of a mist production chamber. The mist generator may be configured to generate the protective wax mist in the mist production chamber. It may be provided for conveying the protective wax mist to the outlet conveyor.

The upstream mist production chamber serves to generate a homogeneous mist even before introduction into the cavity to be preserved. By a conveyor such as a pump to promote the protective wax mist or to generate an overpressure in the mist production chamber, this mist is supplied in the homogenized form the cavity.

The method may find application for supplying the protective wax mist into a cavity between walls of a double-walled hollow body. It can also find application for supplying the protective wax mist in a cavity whose inner walls are covered at least in sections by other wall sections, starting from the positioning of the outlet opening within the cavity. Even surfaces of curved or angled cavities are to be provided by means of the described method advantageously with protective wax. In particular, in such designs can be achieved by the protective wax mist better results than by spraying the protective wax.

According to the invention, the following system is provided for carrying out the method described: The system has a working position at which a workpiece with a cavity to be preserved can be positioned. It has a supply device for supplying a corrosion protection wax in the cavity. The supply device has a mist generator with outlet opening which can be positioned on or in the cavity to be preserved in such a way that the corrosion protection wax can be introduced into the cavity in atomised form (protective wax mist).

The system may have air nozzles for introducing air for movement of the generated protective wax mist within the cavity.

The system may have at least one pressure generator, by means of which in a partial region of the cavity a negative pressure or an overpressure can be generated. The pressure generator may be provided with a control device, is generated by the periodically changing pressure within the cavity.

Furthermore, the system may have further to the described method as well as in connection with the embodiments mentioned components.

BRIEF DESCRIPTION OF THE DRAWINGS

• Fig. 1 und 2 zeigen ein exemplarisches Werkstück mit einem Hohlraum, dessen Oberflächen mit Korrosionsschutzwachs zu versehen sind.
• Fig. 3 zeigt die Einbringung von vernebeltem Korrosionsschutzwachs in den Hohlraum durch eine Austrittsöffnung hindurch an einer endseitigen Stirnseite des Werkstücks. Fig. 4 zeigt den Hohlraum, nachdem sich das Korrosionsschutzwachs an den Wandungen niedergeschlagen hat.
• Fig. 5 zeigt einen möglichen Aufbau eines Nebelerzeugers in Form einer Nebeldüse, durch die hindurch das Korrosionsschutzwachs eingebracht werden kann und dabei zu Nebel zerstäubt wird.
• Fig. 6 zeigt eine Variante, bei der durch Bewegung der Austrittöffnung der Nebelaustrag verbessert ist.
• Fig. 7a und 7b zeigt eine Variante, bei der durch gezielte Erzeugung von Überdruck und/oder Unterdruck im Hohlkörper eine Bewegung des Schutzwachsnebels erzielt wird.
• Fig. 8 und 9 zeigen Varianten, bei denen durch Zuführung von Luft oder durch besondere Ausrichtung von Nebelaustrittsöffnungen ein Drall im Schutzwachsnebel erzeugt wird.
• Fig. 10 zeigt eine Variante, bei der die Nebelerzeugung in einer nicht zum Werkstück gehörigen Nebelerzeugungskammer erfolgt und der erzeugt Nebel erst anschließend dem Hohlraum des Werkstücks zugeführt wird.

Further advantages and aspects of the invention will become apparent from the claims and from the following description of preferred embodiments of the invention, which are explained below with reference to the figures.

• Fig. 1 and 2 show an exemplary workpiece with a cavity whose surfaces are to be provided with anti-corrosion wax.
• Fig. 3 shows the introduction of nebulized corrosion protection wax into the cavity through an outlet opening at an end face of the workpiece. Fig. 4 shows the cavity after the anti-corrosion wax has deposited on the walls.
• Fig. 5 shows a possible construction of a mist generator in the form of a mist nozzle through which the corrosion protection wax can be introduced and is thereby atomized to mist.
• Fig. 6 shows a variant in which the mist discharge is improved by movement of the outlet opening.
• Fig. 7a and 7b shows a variant in which a movement of the protective wax mist is achieved by targeted generation of pressure and / or negative pressure in the hollow body.
• 8 and 9 show variants in which a twist in the protective wax mist is generated by supplying air or by special alignment of mist outlet openings.
• Fig. 10 shows a variant in which the mist generation takes place in a not belonging to the workpiece mist production chamber and the generated mist is only then supplied to the cavity of the workpiece.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The Figures 1 and 2 show an exemplary workpiece 10, which may be, for example, a portion of a sill of a motor vehicle. It puts FIG. 1 a cut and FIG. 2 a perspective, sectional view. As can be seen, a cavity 12 of this sill is limited not only by a cylindrical outer wall 20, but also by partition plates 22.

The aim of the method described here is to cover the surfaces within the cavity with corrosion protection wax. However, said partition plates 22 make it impossible to reach all surfaces starting from an end face region 14 of the cavity 12 by spraying corrosion wax.

FIG. 3 shows how in the method according to the invention, an applicator 30 is introduced with a nozzle, not shown in the figure with outlet opening 32 end in the cavity 12. Through the outlet opening 32 of the applicator then the protective wax mist 40 is introduced into the cavity 12. The protective wax mist 40 consists of fine wax droplets with a mean diameter of less than 120 microns. The protective wax mist 40 is distributed within the cavity 12 and is deposited on the surfaces of the outer wall 20 and the partition plates 22 down.

FIG. 4 shows the cavity with a protective wax layer 50, which has deposited on the walls. In particular, there is also a protective wax layer 50 in areas 52 which would not have been reachable directly from the outlet opening 32 by spraying, but only by the tendency of the protective wax mist 40 to homogeneously distribute in the cavity 12 and precipitate on the surfaces.

FIG. 5 shows by way of example a one-component nozzle forming the mist generator 31. This can be provided at the end in the applicator 30. It has a thin nozzle channel 34, the opening of which defines the outlet opening 32, wherein for the purpose of tearing the corrosion protection wax into fine droplets, a sharp-edged design is provided at edges 36 of this outlet opening 32. The anticorrosive wax is supplied through a supply channel 38 under high pressure. The higher the pressure, the finer are the resulting droplets of corrosion protection wax. It is particularly advantageous if the corrosion protection wax in the channel 38 has a pressure between 80 and 120 bar.

FIG. 6 shows again, similar to the FIG. 3 , the introduction of corrosion protection wax in the cavity. The peculiarity lies in the fact that in the manner illustrated by the arrow 2, the outlet opening 32 is displaced within the cavity. As a result, an even more homogeneous distribution of the mist can be effected. Depending on the depth of penetration of the applicator 30 into the cavity, the required time can be shortened, which it takes until the mist has been homogeneously distributed. This serves to achieve short cycle times.

In the design according to FIG. 7 it is provided that at the two opposite end portions 14, 16 of the cavity 12 each pressure channels 70, 72 are connected. These make it possible to specifically create an overpressure or a negative pressure in the areas 14, 16. In this way, in turn, the cloud of mist 40 can be selectively moved back and forth within the cavity 12, as is illustrated by the arrow 4a, 4b. In particular, the complete coverage of the bulkhead plates 22 with corrosion protection wax is thereby promoted.

FIG. 8 shows a design in which in addition to the applicator 30 two air nozzles 60 are inserted in the end region of the cavity, said air nozzles each define an exit direction of the air, which is not only in the main extension direction 1 of the cavity 12, but in contrast both clockwise or both against are angled in the clockwise direction. As a result, a helical swirl in the mist 40 can be generated, which causes a kind of screwing the fog into the cavity and thereby in turn favors the coverage of difficult access surfaces.

FIG. 9 shows that similar can also be achieved in that the mist generator itself has two outlet openings 32a, 32b, which are angled in opposite directions in order to produce the desired spin can. In addition, the applicator 30 can rotate as a whole.

The embodiment according to FIG. 10 shows a clear difference. Here, a mist-generating chamber 80 belonging to the plant and not to the workpiece is provided, into which the protective wax mist 40 is produced by means of a mist nozzle 31. From here, the mist is fed through a channel 90 to the actual cavity. This can be done via a pump 92 or, for example, by causing, in addition to the protective wax mist 40 via a separate channel, an overpressure in the mist production chamber 80, which pushes the protective wax mist 40 through the channel 90 into the workpiece.

Claims (13)

Method for covering inner walls of a cavity with a protective layer (50) of anti-corrosion wax, in particular for use on vehicle bodies (10) and vehicle body parts, characterized by the following features: a. Anti-corrosive wax is brought by means of a mist generator (31) in nebulized form as protective wax mist (40) and fed through an outlet opening (32) to be preserved cavity (12), and b. the protective wax mist (40) is deposited on inner walls of the cavity (12) and forms here a corrosion protection wax layer (50). Method according to claim 1 with the additional features: a. the protective wax mist (40) consists of air and droplets of corrosion protection wax, and b. the average diameter of the droplets of the supplied mist is <100 .mu.m, preferably <80 .mu.m, in particular preferably <60 .mu.m. Method according to claim 1 or 2 with the additional feature: a. the droplets of the protective wax mist (40) emerge from the outlet opening (32) at a speed <10 m / sec, preferably 5 <m / sec, in particular preferably <1 m / sec. Method according to one of the preceding claims with at least one of the additional features: a. the supply of the protective wax mist (40) takes place at several points or at changing points within the cavity to be preserved (12) and / or b. the protective wax mist (40) is supplied by means of several mist generators and / or by a plurality of outlet openings (32a, 32b) which are arranged at different locations within the cavity (12) to be preserved and / or in different directions relative to the cavity to be preserved (12 ) are arranged. Method according to one of the preceding claims with the additional feature: a. by generating a pressure difference between two disputed portions (14, 16) of the cavity (12), the protective wax mist (40) is moved within the cavity (12), in particular with the following feature: b. by alternately generating an overpressure and a negative pressure in at least a partial area (14, 16) of the cavity, a periodically repeated movement of the protective wax mist (40) in the cavity (12) is produced. Method according to one of the preceding claims with one of the additional features: a. the mist generator generates the protective wax mist by mixing pressurized protective wax and pressurized air, or b. the mist generator (31) generates the protective wax mist (40) by pressurizing protective wax through a nozzle orifice (34), or c. the mist generator generates the protective wax mist by means of a high-frequency oscillating actuator, in particular with the following feature: d. the outlet opening (32), through which the protective wax mist (40) is introduced into the cavity (12), is at least phased in a rotational movement. Method according to one of the preceding claims with the additional features: a. the mist is generated by at least one nozzle opening (34) with a diameter of less than 0.5 mm, preferably less than 0.3 mm, and b. the corrosion protection wax is supplied to the nozzle opening (34) at a pressure of at least 20 bar, preferably at least 60 bar, in particular preferably at least 100 bar. Method according to one of the preceding claims with one of the additional features: a. the protective wax mist (40) exits in a direction out of the outlet opening (32) which is angled with respect to a main extension direction (1) of the cavity (12), and / or b. the protective wax mist (40) is specifically influenced after leaving the outlet opening with regard to its direction of movement, in particular by supplying air from different air nozzles (60) from the outlet opening. Method according to one of the preceding claims with the additional features: a. the exhaust port (32) is preceded by a mist generation chamber (80), and b. the mist generator (31) is designed to generate the protective wax mist (40) in the mist production chamber (80), in particular with the additional feature: c. there is provided conveying means (90) for conveying the protective wax mist (40) into the cavity (12). Method according to one of the preceding claims with one of the additional features: a. the method is used for supplying the protective wax mist (40) into a cavity (12) between walls of a double-walled hollow body, or b. The method is used for supplying the protective wax mist (40) into a cavity (12) whose inner walls, starting from the positioning of the outlet opening (32) within the cavity (12) are at least partially covered by other wall sections (22). Plant for carrying out the method according to one of the preceding claims, having the following features: a. the plant has a working position at which a workpiece (10) with a cavity to be preserved (12) can be positioned, and b. the system has an applicator (30) for supplying a corrosion protection wax (40) into the cavity (12), characterized by the following feature: c. the applicator (30) has a mist generator (31) with outlet opening (32) which can be positioned on or in the cavity (12) to be preserved or a feed to the cavity (12) such that the corrosion protection wax is fogged in form of protective wax ( 40) can be introduced into the cavity (12). Plant according to claim 11 with the additional feature: a. the plant has air nozzles (60) for introducing air for the purpose of moving the generated protective wax mist (40) within the cavity (12). Plant according to claim 11 or 12 with the additional feature: a. the system has at least one pressure generator, by means of which a negative pressure or an overpressure can be generated in a partial area (14, 16) of the cavity (12), preferably with the additional feature: b. the pressure generator is provided with a control device, by the periodically changing pressure within the cavity (12) can be generated.

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