EP1998129B1 - Device for drying objects, in particular varnished automobile bodies - Google Patents

Description

1. a) einem Trockentunnel, dessen Innenraum mit einer Inertgasatmosphäre gefüllt ist und mindestens eine Heizeinrichtung zum Erwärmen der Inertgasatmosphäre aufweist;
2. b) einer UV-Bestrahlungskammer, die dem Trockentunnel nachgeschaltet ist und ebenfalls eine Inertgasatmosphäre enthält;
3. c) mindestens einer UV-Lampe, die in der UV-Bestrahlungskammer angeordnet ist und eine mit einem Kühlmedium arbeitende Kühleinrichtung aufweist;
4. d) einem Fördersystem, welches die Gegenstände durch den Trockentunnel und die UV-Bestrahlungskammer hindurchführt.

The invention relates to a device for drying objects, in particular painted vehicle bodies with

1. a) a drying tunnel, the interior of which is filled with an inert gas atmosphere and has at least one heating means for heating the inert gas atmosphere;
2. b) a UV irradiation chamber, which is connected downstream of the drying tunnel and also contains an inert gas atmosphere;
3. c) at least one UV lamp, which is arranged in the UV irradiation chamber and has a working with a cooling medium cooling device;
4. d) a conveyor system which passes the articles through the drying tunnel and the UV irradiation chamber.

By "drying device" is meant here all devices in which a coating material is transferred from the state after the application to the final state, be it by the removal of solvents, melting, crosslinking or the like.

Recently, coatings increasingly gain importance, which are cured in an inert gas atmosphere under UV light must be to prevent unwanted reactions with components of the normal atmosphere, especially with oxygen. These novel coatings are characterized by a very high surface hardness and short curing times. The latter advantage is in paint shops, which are operated in a continuous cycle, directly into smaller plant lengths, which of course leads to significantly lower investment costs.

An example of such a drying device is in DE 10 2004 025 525 B3 described.

The DE 10 2005 050 371 A1 describes a UV irradiation chamber with inert gas atmosphere, locks and conveyor system. The UV lamps heat the inert gas within the irradiation chamber.

In all industrial systems, but especially in drying devices for large objects, as they are, for example, vehicle bodies, there is a constant need for an efficient use of energy. It is therefore an object of the present invention, a device of the type mentioned in such a way that energy losses are largely avoided.

1. e) das Kühlmedium der UV-Lampe zum Trockentunnel zurück führbar und dort wärmemäßig an die darin herrschende Inertgasatmosphäre so ankoppelbar ist, dass die von der UV-Lampe erzeugte Wärme teilweise zur Erwärmung des Trockentunnels beiträgt.

This object is achieved in that

1. e) the cooling medium of the UV lamp can be guided back to the drying tunnel and there heat-coupled to the prevailing inert gas atmosphere in such a manner that the heat generated by the UV lamp partially contributes to heating the drying tunnel.

The invention is based on the knowledge that the heat generated in the or the UV lamps as "waste" can be used meaningfully and in particular for heating the inert gas atmosphere, which is located in the drying tunnel. In this way, the performance of the used there Heating devices are reduced. This realization is not as banal as it may seem to sound at first. In fact, it requires a very intimate knowledge of the thermotechnical processes and processes in a generic drying device. Whether the recovery of heat generated in a given part of the plant and its reintroduction into the plant is worthwhile elsewhere requires very precise calculations and investigations.

The cooling medium can preferably be coupled to the inert gas atmosphere via a heat exchanger. In this way, the cooling medium, which is preferably water or air, is separated from the inert gas atmosphere and the inert gas atmosphere is clean.

Preferably, the cooling medium in the heating region is thermally coupled to the inert gas atmosphere of the drying tunnel. As is well known, the painted and dried articles are first fed into the drying tunnel into an area of increasing temperature to initiate drying operations by initially slow heating, which are often associated with the evolution of gases and / or vapors. Since in this area, as mentioned, the temperature of the inert gas atmosphere is still relatively low, coming from the or the UV lamps, heated and not too high temperature having cooling medium there is particularly well to support the heaters.

Condensate traps are preferably used to remove condensable impurities from the inert gas atmosphere. When the inert gas is recovered by evaporation of a liquid, the condensate traps can be energetically connected to the evaporator device for energy saving be coupled.

In certain applications, it has proved to be advantageous if a plurality of UV lamps is arranged on at least one wall of the UV irradiation chamber such that they can irradiate the object located in the UV irradiation chamber surface. Preferably, both the side walls and the ceiling of the UV irradiation chamber are provided with surface UV lamps.

In other cases, it is favorable to arrange a plurality of UV lamps in a portal in such a way that the object to be irradiated can move through the portal. The arrangement of UV lamps in such portals is rather linear. Frequently more powerful UV lamps are used in portals than in the case of planar arrangement.

Of course, it is possible to use in one and the same drying device, both types of arrangement of UV lamps in a row.

For irradiating the interiors of the objects, one or more UV lamps can also be attached to the arm of a robot, with which they can be introduced into these interiors.

Figur 1

im Vertikalschnitt einen Gesamtüberblick über eine Trockenvorrichtung für Fahrzeugkarosserien;

Figur 2

eine Vergrößerung des linken Endbereiches der Figur 1;

Figur 3

eine Draufsicht auf den in Figur 2 dargestellten Endbereich der Trockenvorrichtung;

Figur 4

eine Vergrößerung des rechten Endbereiches der Figur 1;

Figur 5

eine Draufsicht auf den in Figur 4 dargestellten Endbereich der Trockenvorrichtung.

An embodiment of the invention will be explained in more detail with reference to the drawing; show it

FIG. 1

in vertical section an overall view of a drying device for vehicle bodies;

FIG. 2

an enlargement of the left end of the FIG. 1 ;

FIG. 3

a top view of the in FIG. 2 illustrated end portion of the drying device;

FIG. 4

an enlargement of the right end of the FIG. 1 ;

FIG. 5

a top view of the in FIG. 4 illustrated end portion of the drying device.

First, it will open FIG. 1 Reference is made, in which a generally designated by the reference numeral 1 drying device for vehicle bodies is shown in vertical section and in the overall overview. This drying device 1 is integrated into a painting line. It is preceded by the actual paint booth to think in which the vehicle bodies, which are provided in the figures with the reference numeral 2, are coated with a varnish in an inert gas atmosphere and UV curing varnish. Downstream of in FIG. 1 The drying device shown is a cooling device in which the dried, so provided with a polymerized paint layer vehicle bodies 2 are cooled to a suitable temperature for further processing. Both the upstream paint booth and the downstream cooling device are of conventional construction and are therefore not described in detail.

The vehicle bodies 2 are cyclically or continuously moved through the drying device 1 by means of a conveyor system, not shown, and in the direction of the arrow 3 of FIG. 1 ie in FIG. 1 left to right. The vehicle bodies 2 first pass into a so-called A lock 4, in which they be raised by a lifting device 5 to a higher level. The purpose of the A-lock 4, which is known to those skilled in the art, in the present case not only in the saving of heat energy but also in the vehicle bodies 2 from the "normal atmosphere" in which they are at the lower level, in an inert gas atmosphere, which prevails in the parts of the drying device 1 described below.

From the A lock 4, the vehicle bodies 2, following the direction of the arrow 3, enter into different drying chambers 6 of the drying device 1, which together form a drying tunnel. All these drying chambers 6 are heated in a known manner by means of a circulating air heater, not shown, to a certain temperature. In the first drying chambers 6, this temperature rises initially; this area is called "heating zone". After passing through the heating zone, the vehicle bodies 2 fall into a series of drying chambers 6, in which essentially a constant temperature is maintained. The number of drying chambers 6 belonging to the heating zone and the number of drying chambers 6 belonging to the "holding zone" is chosen according to the respective requirements and is in FIG. 1 only as an example.

After passing through all the drying chambers 6, the vehicle bodies 2 are transported by means of the conveyor system into a UV irradiation chamber, which bears the reference numeral 7 as a whole. The UV irradiation chamber 7 in turn is divided into three sections 7a, 7b, 7c. In the first section 7a, a multiplicity of UV lamps 8 are arranged along the chamber walls, which as it were allow a "total illumination" of the vehicle bodies 2 from the sides and from above. After going through the intermediate zone 7b which is free from UV lamps, the vehicle body is guided into the section 7c in which UV lamps 9 are mounted on robots with which the interior is irradiated after the doors and / or hoods have been opened by door / hood opener systems. Behind the outlet of the UV irradiation chamber 7 is an intermediate chamber 10, followed by a so-called piston lock 11, whose meaning will be discussed below, and a further A-lock 12, in which the vehicle bodies 2 by means of a hoist 13 back to the original level are lowered. At the rear end of the drying device 1 in the direction of movement (arrow 3) there are outlet chambers 14, which can serve for intermediate cooling and / or quality control.

At least the two A-locks 4, 12 and the piston lock 11 and the UV-irradiation chamber 7 are provided with inlet and outlet ports, for example in the form of lifting gates, which are opened only to the passage of a vehicle body 2 and so an atmospheric separation to adjacent Ensure chambers of the drying device 1. Details in this connection are not of interest here.

The UV lamps 8, 9, which are located in the UV irradiation chamber 7, have a considerable connected load and require cooling. For this purpose, cooling circuits are provided, through which a cooling medium circulates. The latter may be a gas or a liquid. The following is based on the use of cooling water. The heated by the UV lamps 8, 9 cooling water is supplied via the line 15 against the direction of movement (arrow 3) of the vehicle bodies 2 the first two drying chambers 6 in the heating of the drying device 1, where they in a not shown Heat exchangers deliver a part of their heat content to the atmosphere circulated there. In this way, 6 heating energy is saved in the first two drying chambers. The cooled cooling water is returned via the line 16 back into the UV irradiation chamber 7 and there to the UV lamps 8, 9.

Below the drying chambers 6 are at two points condensate traps 17, 18, which may optionally be cooled and on which auskondensierbare impurities from the atmosphere of the drying chambers 6 can be removed. You can be energetically coupled with the evaporator described in more detail below, so that energy is saved here.

As already mentioned, the interior of the drying device 1 is filled with inert gas, for example with nitrogen, CO ₂ , a noble gas or an oxygen-poor flue gas. The inert gas atmosphere begins in the upper region of the A lock 4 and ends in the piston lock 11.

The piston lock 11 is provided to prevent inert gas losses with a piston 19 whose base surface (seen from above) is adapted to the horizontal cross section of the piston lock chamber. If there is no vehicle body in the piston lock 11, the piston 19 can be pressed down. In this case, the inert gas atmosphere located there is introduced via a line 20 in that drying chamber 6, with which the holding zone of the drying device 1 begins. Via a further line 21, the inert gas atmosphere located in this drying chamber 6 is guided back into the piston lock 11. This replacement of the inert gas serves, in particular, for rinsing the vehicle bodies 2, which enter the holding area of the drying device 1, to completely remove adherent normal atmosphere.

Below the higher level section of the drying apparatus 1, in the vicinity of the UV irradiation chamber 7, a storage tank 22 is arranged, in which liquid inert gas, for example liquid nitrogen, is located. With an evaporator device, not shown, the inert gas can be evaporated as needed. The storage tank 22 is connected via a line 23 to the interior of a cylinder 24, in which a piston 25 by means of a suitable drive device is movable. Another line 26 connects the interior of the cylinder 24 with the interior of the UV irradiation chamber 7. The lines 23 and 26 include valves, not shown, as required for the operation described below.

The line 23 can also be passed through heat exchangers of the condensate traps 17, 18, so that on the one hand the condensate traps 17, 18 are cooled and on the other hand the inert gas fed to the UV irradiation chamber 7 is heated.

The drying device 1 described above operates as follows:

The freshly painted and only a slight evaporation subjected to vehicle bodies 2 are retracted by means of the conveyor system in the A lock 4 and there brought by means of the lifting mechanism 5 to the higher level. The vehicle bodies 2 already pass into an inert gas atmosphere which, in countercurrent, coming from the UV irradiation chamber 7, has passed through all the chambers of the drying apparatus 1. Due to carryover of normal atmosphere, the inert gas atmosphere in the region of the inlet A lock 4 is the most heavily polluted. There the polluted inert gas is withdrawn via another line 27 and either discarded or reused after cleaning.

The vehicle bodies 2 now move to the higher level in FIG. 1 to the right (direction of arrow 3) and get into the first drying chambers 6 of the drying tunnel. There, they are heated at still behässismäßig low temperatures of the circulating atmosphere, which has received its heat content at least partially from the UV lamps 8, 9 in the UV irradiation chamber 7. On the way through the heating zone, the temperature is slowly increased. The individual drying chambers 6 can be separated from each other by gates, but they do not have to. In any case, it is advantageous if the atmospheres in the individual drying chambers 6 are somewhat separated from one another so that a defined temperature profile in the heating zone can be maintained. Condensable substances that evaporate from the vehicle bodies 6 in the heating zone are condensed out with the condensate trap 17 and removed.

The vehicle bodies 2 then enter the first drying chamber 6 of the holding zone. There they are, as already explained above, purged with inert gas, which comes from the piston lock 11, where the inert gas atmosphere is still relatively clean. On further passage through the drying chambers 6 of the holding zone any remaining solvents are expelled and the coating material prepared for crosslinking. Condensable material accumulating in this area is removed via the condensate trap 18 so that the inert gas is not contaminated unnecessarily.

Now, the vehicle bodies 2 enter the UV irradiation chamber 7 on. There, the inert gas atmosphere must be the cleanest so as not to interfere with the crosslinking process that takes place under the influence of the UV light emitted by the UV lamps 8, 9. Therefore, the UV irradiation chamber 7 at regular intervals, in the extreme case at each cycle of the drying device 1, newly filled with inert gas. In order to achieve high flow rates, the filling with inert gas must be done quickly. Since the evaporation of liquid inert gas in the reservoir 22 by evaporators with reasonable power can not proceed indefinitely, the piston-cylinder unit 24, 25 is provided. She works as follows:

During the time in which the coating cures on one (or more) vehicle bodies 2 in the UV irradiation chamber 7 under irradiation with UV light, the evaporator means in the storage tank 22 continuously generates gaseous inert gas. This accumulates in the cylinder 24, wherein the piston 25 is moved back accordingly. At the end of the irradiation time, as much gaseous inert gas has accumulated in the cylinder 24, as is required for the next irradiation process in the UV irradiation chamber 7. Thus, if the vehicle bodies 2 which have been irradiated in the cylinder 24 during the collection of the evaporated inert gas, have moved out of the UV irradiation chamber 7, by inserting the piston 25 into the cylinder 24, the inert gas accumulated there via the line 26 in the UV irradiation chamber 7 are pressed. This is possible in a comparatively short time, although the evaporator device can evaporate the liquid inert gas in the storage tank 22 only relatively slowly.

The vehicle bodies 2 are thus in a highly pure inert gas atmosphere within the UV irradiation chamber 7 initially irradiated by the UV lamps 8, which illuminate surface of the two sides and from above the vehicle body 2. In this case, the polymerization of the coating material takes place on the outer surfaces of the vehicle bodies 2. After passing through the intermediate region 7b in the UV irradiation chamber 7, the interiors of the vehicle bodies 2 are irradiated by the UV lamps 9 guided by robots. About the intermediate chamber 10, the vehicle bodies 2 are first introduced into the piston lock 11 and then from this into the upper region of the A-lock 12. By lowering the lifting device 13, the vehicle bodies 2 return to the low level and leave the drying device 1 via the outlet chambers 14 in the direction of the cooling device.

Part of the waste heat of the UV lamps 8, 9 can also be used to preheat the inert gas introduced from the storage tank 22 via the cylinder 24 into the UV irradiation chamber 7 or to operate the condensate traps 17, 18.

Claims (9)

1. A device for drying objects, in particular painted vehicle bodies, having

   a) a drying tunnel, whereof the interior is filled with an inert gas atmosphere and which has at least one heating device for heating the inert gas atmosphere;

   b) a UV radiation chamber, which is connected downstream of the drying tunnel and likewise contains an inert gas atmosphere;

   c) at least one UV lamp, which is arranged in the UV radiation chamber and has a cooling device operating with a coolant;

   d) a conveyor system, which guides the objects through the drying tunnel and the UV radiation chamber;
   wherein

   e) the coolant of the UV lamp (8, 9) can be returned to the drying tunnel (6) and can be thermally linked there to the inert gas atmosphere prevailing therein so that the heat generated by the UV lamp (8, 9) partially contributes to heating the inert gas atmosphere in the drying tunnel (6).
2. A device according to Claim 1, characterised in that the coolant can be linked to the inert gas atmosphere by way of a heat exchanger.
3. A device according to Claim 1 or 2, characterised in that the coolant is a liquid, in particular water.
4. A device according to Claim 1 or 2, characterised in that the coolant is a gas, in particular air.
5. A device according to one of the preceding claims, characterised in that the coolant in the heating area can be thermally linked to the inert gas atmosphere in the drying tunnel (6).
6. A device according to one of the preceding claims, characterised in that a plurality of UV lamps (8) are arranged on at least one wall of the UV radiation chamber (7) in such a way that they can subject the object located in the UV radiation chamber (7) to extensive irradiation.
7. A device according to one of the preceding claims, characterised in that a plurality of UV lamps are arranged in a portal in such a way that the object (2) to be irradiated can move through the portal.
8. A device according to one of the preceding claims, characterised in that at least one UV lamp (9) is arranged on the arm of a robot.
9. A device according to one of Claims 3 or 5 to 8, characterised in that at least one condensate trap (17, 18), which is in thermal exchange with a vaporiser unit for the liquid coolant, is arranged in the inert gas atmosphere.

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