EP1321731B1 - Energy transmitter as part of a coating and/or drying plant, especially for a paint coating - Google Patents

Description

The invention relates to an energy transmitter as part of a coating and / or drying plant, in particular for a paint coating according to the preamble of claim 1.

In conventional coating processes, different coating materials are sometimes used in several layers, such as powder coatings, fillers, basecoats, clearcoats, etc., which must be melted or dried at reaction temperatures of about 80 ° to about 200 °. In well-known coating systems, which are designed for standard coatings of many components, such as housings, bodies, metal structural parts, etc., conventional convection drying is performed with hot air, which require enormous energy costs and long drying times. The energy transmitter used here is the hot air heated by heating elements. In the case of a continuous transport of the components through drying tunnels, these have a great length, so that correspondingly complex constructions are required in large building complexes. In addition to these coating and varnishing plants with conventional conventional circulating air drying by hot air, multi-stage processes in conjunction with other energy transmitters are known, with which energy is applied in the varnish coating for the purpose of melting and / or drying:

In a known paint shop (DE 198 57 940 C1), a combined UV / IR curing is utilized, wherein in several successive irradiation intervals to be cured paint material with IR and UV radiation is irradiated alternately. For this purpose, a special expensive paint material is required, the application is preferred in refinishes.

Next, a painting is known in which a two-stage drying process is used for the paint drying (DE 195 03 775 C1), being used in the first drying stage as an energy transmitter infrared emitters. A problem with these infrared emitters is that the radiation intensity and thus the effective application of energy in the coating material decreases with the square of the distance. Therefore, the infrared emitters are in their shape adapted to the object to be dried exactly contoured and brought by means of controlled actuators in the manner of robots at a small distance to the surface, so that remains to increase the effectiveness of a small intermediate gap. This represents a considerable expenditure on equipment. As a result, in particular in the case of more structured components, a continuous transport by a drying device is not possible, since the object must be locally held at the location of the infrared emitter during the first drying step. In a second dryer booth then a subsequent drying is carried out as a second drying stage with predominantly stationary infrared emitters, which in turn requires a considerable amount of time.

Next, a painting is known (DE 38 14871 A1), in which only an infrared drying is used, which operates at a radiation frequency in the near infrared (NIR) at 1.0 to 4.0 microns. Again, the aforementioned problems for efficient energy application occur. There is also the problem that hidden areas, such as undercut Area on which the IR radiation does not impinge directly, only slightly heated and cured.

In summary, it should be noted that melting and / or curing of coating materials requires a very high expenditure of energy and time in the previously known coating and varnishing plants. This effort is also due to the fact that a component as a carrier of the coating material, in particular in a good heat conductive metal component itself as well as the ambient air to the required temperature of the coating material heated must so that the adjacent coating material can assume the required high temperature. In the case of components with larger material masses, the further problem then arises that the components which have been heated up with great expenditure of energy must be cooled down time-consuming again for further handling, with high energy consumption once again being required for active cooling.

The object of the invention is therefore to provide an energy transmitter as part of a coating and / or drying system, in particular for a paint coating with the essential process energy savings are possible.

This object is achieved with the features of claim 1.

According to claim 1, the energy transmitter comprises at least two transmitter surface elements as antenna elements. Each of the transmitter surface elements has a glass carrier plate which carries a radiation layer on a glass rear surface and whose opposite free glass front surface is directed to a position for an object to be dried or a surface of a component with applied coating material. At a distance and approximately parallel to the glass rear surface and at least in size, a surface reflector made of metal material is arranged.

The respective radiation layer is designed to emit electromagnetic radiation in a frequency band, the frequency band having to cover at least characteristic natural frequencies in the infrared of an object or coating material to be dried. Such molecular natural frequencies are especially in the ultra-red range of about 10 ⁹ to 10 ¹² hertz. The emission layer can be excited by means of a control device for emitting the at least one frequency band, so that natural frequencies of the object to be dried or of the coating material can be excited in resonance. The arrangement seeks the appropriate corresponding resonant frequency to a natural frequency from the radiated frequency band for targeted energization with high energy density according to conventional resonance processes out. By a targeted adaptation of the radiated frequency band to the respective metrologically detectable natural frequencies, in particular of paint materials thus an energy input directly into these materials with high energy density is possible without adjacent environmental areas, especially component carrier areas are mitaufgeheizt to high temperatures or mitaufgeheizt. In addition, in contrast to conventional IR emitters, only a minimal increase in temperature occurs in the emission layer of the energy transmitters, which work here as antenna elements. Since the components to be coated themselves do not necessarily have to be heated to high temperatures, cooling processes which are otherwise necessary after a paint drying process can be saved or at least considerably reduced.

Overall, according to the invention thus coating and / or drying systems can be constructed, which can be operated with significantly less energy and time.

Extensive tests have shown that, in particular, the specified structure of the transmitter surface elements in conjunction with the surface reflector and the specified radiation direction leads to a significant increase in effectiveness.

In a specific arrangement of the transmitter surface elements according to claim 2, these are rectangular or square formed with flat glass surfaces and arranged in total in at least one plane, preferably in opposing planes. This results in a simple structural design with advantageous large-area Gesamtabstrahlflächen for effective energization. Experiments have shown that a particularly effective radiation with transmitter surface elements with edge lengths of about 20 cm to 80 cm, preferably of about 40 cm is possible.

With the features of claim 3, a closed, gas-tight front plane can be made if necessary.

In a particularly preferred development according to claim 4, the planes of the transmitter surface elements form inner walls of a tunnel and are arranged on its side walls and / or on the ceiling wall and / or on the bottom wall. Through such a tunnel in particular components for a paint drying can be transported automatically.

With the features of claim 5, a radiation layer is claimed, which is highly suitable for the radiation of the specified frequency bands. Claim 6 is directed to further concretions and advantageous embodiments.

According to claim 7, the transmitter surface elements each have electrical conductors on opposite side regions of the glass rear surfaces equipped with the radiation layer, wherein all the transmitter surface elements are connected in parallel with a harmonic generator of the control device. The harmonic generator comprises an electrical component, which has a steep current slew rate when driven with a drive oscillation and is thus suitable for generating a high harmonic content. These conductors are preferably formed as copper foil strips, wherein a coupling to the radiation layer is capacitive or inductive. As an electronic component with the specified properties, a triac or double MOSFET or optionally also an ultrafast switch is suitable. In such an excitation, the emission layer acts in the manner of a frequency transformer, with relatively smaller excitation frequencies leading to the high emission frequencies with the specified ultra-frequency band.

With the development according to claim 8, it is proposed to excite a number of the transmitter surface elements with a frequency in the megahertz range and the other transmitter surface elements with a frequency in the gigahertz range. Due to the above function of the radiation layer as a frequency converter or frequency multiplier to higher frequencies with respect to the respective excitation frequency with such a split excitation of the transmitter surface elements a wide coverage of natural frequency ranges possible, if this is required for specific applications. This may be true, for example, if material mixtures which have relatively widely spaced natural frequencies suitable for the resonance purposes according to the invention are used as the coating material.

According to claim 9, the surface reflector should be formed from at least one viable metal sheet, on which the transmitter surface elements are held by means of insulation elements. The distance between the surface reflector and the transmitter surface elements is for an optimum effect at about 1 cm to 10 cm, preferably about 4 cm. This distance is easily predetermined by a corresponding configuration of the insulation elements. Such an arrangement results in a simple and inexpensive construction. The surface reflector itself can turn without the need for an electrical installation be mounted on suitable supporting frames or supporting walls. The radiation layer is in such an arrangement in the intermediate gap between the transmitter surface elements and the surface reflector and is thus advantageously protected even in a harsh operation against mechanical and possibly chemical influences. The uncoated outwardly directed glass surface, however, is largely insensitive and in particular can be kept simply clean, which is essential for effective and trouble-free radiation. The uncoated glass surfaces are also not affected by the chemicals usually occurring in paint shops during melting and drying, such as solvent vapors. High, trouble-free service life with low maintenance costs are thus guaranteed.

Claim 10 also claims the construction of an automatically operable paint coating system, wherein in a first device as the first station, the coating material is applied in liquid or powdered or granular form. This can be done advantageously in a conventional manner according to claim 10 electrostatically and / or by spraying. A second device comprises in a second station the energy transmitter described above, whereby the coating-free material, preferably a powder coating material, can be melted and / or dried. As a result, flawless, well-retaining coatings are achieved with very low energy consumption and short treatment times. To be coated components, such as metal structural parts, bodies or metal housing can in preferably tunnel-like systems continuously or optionally cyclically by means of transport devices, such. B. be transported automatically with conveyor belts.

Powder coatings having natural frequencies in the range of wavenumbers of about 1000 to 1800 cm ^-1 , which according to claim 13 are applied to components made of metal material, have proved particularly suitable.

With reference to a drawing, the invention is explained in more detail:

Fig. 1

eine schematische, perspektivische Darstellung eines Energie-transmitters als Bestandteil einer Beschichtungs- und Trockenanlage für eine Lackbeschichtung,

Fig. 2

eine schematische, vergrößerte Detaildarstellung der Einzelheit A der Fig. 1, und

Fig. 3

eine schematische, teilweise perspektivische Darstellung eines Transmitter-Flächenelements mit auf einer Glasrückfläche aufgebrachter Abstrahlschicht.

Show it:

Fig. 1

a schematic, perspective view of an energy transmitter as part of a coating and drying system for a paint coating,

Fig. 2

a schematic, enlarged detail view of the detail A of Fig. 1, and

Fig. 3

a schematic, partial perspective view of a transmitter surface element with applied on a glass rear surface radiating layer.

FIG. 1 schematically and perspectively shows an energy transmitter 1 as part of a coating and drying installation 2 for a paint coating. This coating and drying unit 2 has in a first station, not shown, a first means for the order of a z. B. powder coating as a coating material on a surface of a component to be coated 3, z. B. a motor vehicle body on. The powder coating has natural frequencies in the range of wave numbers of about 1000 to 1800 cm ^-1 and is electrostatically applied to the component 3 in the first device. The component 3 together with the electrostatically adhering powder coating is conveyed by means of a transport device 4 continuously or intermittently through the first device not shown here and passes after passing through this first station to a schematically shown in FIG. 1 second station 5, the first station is downstream and includes a tunnel 7, through which the component 3 by means of Transport device 4 is conveyed in the desired manner continuously or intermittently.

As can be seen in particular from FIG. 1, are on the inner walls of the tunnel 7, d. H. arranged on the side walls 8 and on the ceiling walls 9 each have a plurality of the energy transmitter 1 forming transmitter surface elements 10, which are preferably substantially adjacent to each other and z. B. form a narrow gap between them, in which, as shown schematically in Fig. 2, an elastically insulating sealing strip 21 can be used. As a result, a closed, gas-tight front plane is achieved. By way of example, these transmitter surface elements are approximately rectangular in shape and each have a glass carrier plate 11, as can be seen in particular from FIGS. 2 and 3, which show enlarged schematic detail views. On opposite sides of this glass rear surface 12 13 electrical conductors 14, 15 are arranged on opposite sides of this glass rear surface 12, which are connected in parallel with a harmonic generator of a in 3 only extremely schematically and exemplified control device 16 are connected. This harmonic generator of the control device 16 comprises an electrical component, which has a steep current rise speed corresponding to a steep rising edge when driven with a drive oscillation and is therefore suitable for generating a high harmonic content. As a result, the transmitter surface elements 10 can be excited with a frequency in the megahertz range or with a frequency in the gigahertz range.

One of the glass rear surface 12 opposite free glass front surface 17 of the transmitter surface elements 10 is directed to the vehicle body 3 to.

The inner walls 18 of the tunnel 7 in this case form a surface reflector 20 and are formed from a load-bearing metal sheet on which the transmitter surface elements 10 are held via insulation elements 19 shown in FIG. 2. The distance between the surface reflector 20 and the transmitter surface elements 10 is z. B. approximately between 1 cm to 10 cm.

With regard to the composition of the radiation layer 13, reference is made to the claims 4 and 5 and the corresponding passages in the introduction to the description.

As soon as the component 3 with the electrostatically adhering powder coating is transported through the tunnel 7 by means of the transport device 4, an electromagnetic radiation in the ultra-red is emitted by the respective emission layer 13 on the transmitter surface elements 10 whose frequency band covers the characteristic natural frequencies of the powder coating, so that this is melted onto the component 3 and dried.

Claims (13)

1. Energy transmitter as a component part of a coating and/or drying plant, especially for applying a paintlike coating material, characterized in that the energy transmitter (1) includes at least two transmitter surface elements (10) as antenna elements, in that each of said transmitter surface elements (10) has a glass carrier plate (11) which bears a radiation layer (13) on a rear glass surface (12) and on the opposite free front glass surface (17) is directed to a position for an object to be dried or a surface of a component (3) with coating material applied, in that a surface reflector (20) of a metal material is arranged at a distance from and approximately parallel with the rear glass surface (12) and at least in its size, in that the respective radiation layer (13) is designed to give off electromagnetic radiation in a frequency band covering at least characteristic natural frequencies in ultrared of an object or coating material to be dried, and in that the radiation layer (13) is excitable by means of a control device (16) to give off the at least one frequency band so that natural frequencies of the object or the coating material to be dried are excitable in resonance.
2. Energy transmitter as a component part of a coating and/or drying plant according to Claim 1, characterized in that a plurality of rectangular or square transmitter surface elements (10) are used which are arranged side by side in at least one plane.
3. Energy transmitter according to Claim 2, characterized in that an electrically insulating sealing strip is used between adjoining edges of the transmitter surface elements.
4. Energy transmitter as a component part of a coating and/or drying plant according to Claim 2 or 3, characterized in that the transmitter surface elements (10) form interior walls (18) of a tunnel (7) and are arranged on the side walls (8) and/or on the ceiling wall (9) and/or on the floor wall, and an object to be dried or a component (3) with applied coating material is transportable through the tunnel (7).
5. Energy transmitter as a component part of a coating and/or drying plant according to any one of Claims 1 to 4, characterized in that the radiation layer (13) is formed on the glass carrier plates (11) by application of the following coating mass which consists of binding agent, insulator, dispersing agent, water and graphite and is composed of

   a. 55 to 65% amount of substance fractions of a base material comprising

   • 39 to 49% amount of substance fractions binding agent,

   • 18 to 23% amount of substance fractions insulator,

   • 18 to 24% amount of substance fractions dispersing agent,

   • 12 to 16% amount of substance fractions distilled water

   and

   b. 35 to 45% amount of substance fractions of graphite,
   with the binding agent being composed of

   • 69.06 to 75.54% amount of substance fractions distilled water,

   • 4 to 6% amount of substance fractions sulphurated oil,

   • 0.16 to 0.24% amount of substance fractions phenols, or 0.05 to 0.5% amount of substance fractions benzisothiazolinone,

   • 15 to 19% amount of substance fractions casein,

   • 0.8 to 1.2% amount of substance fractions urea,

   • 2 to 3% amount of substance fractions thinning agent, and

   • 2.5 to 3.5% amount of substance fractions caprolactam.
6. Energy transmitter as a component part of a coating and/or drying plant according to Claim 5, characterized in that the sulphurated oil is sulphated castor oil, in that the phenols are carbonized phenols produced by cracking, or benzisothiazolinone is used, in that the thinning agent is an alkaline thinning agent and/or a solvent based on aromatics and/or alcohol and/or ester and/or ketone, in that the insulator is an insulating carbon black, in that the dispersing agent is an inorganic and/or organic, monomeric and/or polymeric substance, and in that the coating mass comprises a thixotropic agent.
7. Energy transmitter as component part of a coating and/or drying plant according to any one of Claims 1 to 6, characterized in that the transmitter surface elements (10) each have electrical conductors (14, 15) on opposite side areas of the rear glass surfaces (12) provided with the radiation layer (13), and all transmitter surface elements are connected in parallel with a harmonic generator of the control device (16), comprising an electrical block which, upon control with a control oscillation, shows a steep current increase rate in accordance with a steep rising curve and thus is suitable for generating a high harmonic component.
8. Energy transmitter as a component part of a coating and/or drying plant according to any one of Claims 1. to 7, characterized in that a number of the transmitter surface elements (10) are excitable with a frequency in the megahertz range and the other transmitter surface elements (10) are excitable with a frequency in the gigahertz range.
9. Energy transmitter as a component part of a coating and/or drying plant according to any one of Claims 1 to 8, characterized in that the surface reflector (20) is formed of at least one load-bearing-capable metal plate on which the transmitter surface elements (10) are held via insulation elements (19), the distance between the surface reflector (20) and the transmitter surface elements (10) preferably being approximately 1 cm to 10 cm.
10. Energy transmitter as a component part of a coating and/or drying plant according to any one of Claims 1 to 9, characterized in that a first installation is provided for the application of a liquid or powder or granular coating material on at least one part of a surface of a component (3), and the first installation for the application of the coating material is arranged in a first station, through which the component to be coated is capable of being transported continuously or in cycles by means of transport equipment (4), and in that a second installation (6) is provided which comprises the controllable energy transmitter (1) with an effective direction onto the surface of the component (3) with applied coating material, wherein the coating material, preferably a powder coating material, is fusible and/or dryable by means of the energy transmitter (1), and in that the second installation is arranged with the energy transmitter in a second station (5) which is arranged downstream of the first station and through which the component (3) is transportable continuously or in cycles by means of the transport equipment (4).
11. Energy transmitter as a component part of a coating and/or drying plant according to Claim 10, characterized in that the application of the coating material in the first installation is done electrostatically and/or by spraying.
12. Energy transmitter as a component part of a coating and/or drying plant according to any one of Claims 1 to 11, characterized in that a powder coating material is used as the coating material, with natural frequencies in the range of wave numbers of approximately 1000 to 1800 cm^-1.
13. Energy transmitter as a component part of a coating and/or drying plant according to Claim 12, characterized in that the components (3) to be coated consist of a metal material.

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