WO2009092518A1

WO2009092518A1 - Device for drying objects, particularly coated vehicle bodies

Info

Publication number: WO2009092518A1
Application number: PCT/EP2009/000100
Authority: WO
Inventors: Werner Swoboda
Original assignee: Eisenmann Anlagenbau Gmbh & Co. Kg
Priority date: 2008-01-22
Filing date: 2009-01-10
Publication date: 2009-07-30
Also published as: EP2232182B1; EP2232182A1; DE102008005582B3

Abstract

A device (1) for drying objects, particularly painted vehicle bodies (10), comprises a drying tunnel (4) known per se, wherein the interior thereof is filled with an inert gas atmosphere and wherein the objects can be subjected to an electro-magnetic radiation and/or heat in said tunnel. An inlet air-lock region (3) is connected upstream of the drying tunnel (4) and an outlet air-lock region (5) is connected downstream of the drying tunnel (4). Both air-lock regions (3, 5) comprise a gas exchange chamber (16, 31) that can selectively be connected to a pump (42), which can suction off the atmospheres present in the gas exchange chambers (16, 31) and can transport them into the outside atmosphere, or via a controllable valve (19, 28) can be directly connected to the outside atmosphere. Said device can carry out the required atmospheric change in a very short amount of time in both air-lock regions (3, 5).

Description

Device for drying objects, in particular painted vehicle bodies ==================================== =======

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

a) a drying tunnel, the interior of which is filled with an inert gas atmosphere;

b) an inlet sluice area, which is connected upstream of the drying tunnel, comprising at least one gas exchange chamber and separating the inert gas atmosphere prevailing inside the drying tunnel from the outer normal atmosphere;

c) an outlet lock area downstream of the drying tunnel, comprising at least one gas exchange chamber and separating the inert gas atmosphere within the drying tunnel from the outer normal atmosphere;

d) a conveyor system which passes the articles through the inlet lock area, the drying tunnel and the outlet lock area;

e) a storage tank for inert gas, with the

Gas exchange chambers of the inlet lock area and the outlet lock area is connectable.

By "drying" is meant here all processes by which a coating material from the state the application is transferred to the final state, be it by removal of solvents, melting, crosslinking o. Ä ..

In recent years, increasingly gaining coatings importance in an inert gas atmosphere z. B. must be cured under UV light to prevent unwanted reactions with components of the normal atmosphere, especially with oxygen. These novel coatings are characterized by a very high surface quality and short reaction 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.

While in conventional dryers or dry processes that work with normal air as the atmosphere, the amount of air that is introduced into the dryer and out of this, out

Cost reasons is of less importance, must be paid in inert gas atmospheres on the lowest possible consumption.

A device of the aforementioned type is described in DE 10 2004 025 525 B3. Here, the inlet-lock area essentially comprises three chambers: a first, which is filled with normal atmosphere and to which the freshly coated objects are supplied by the coating station. A second chamber is partially below the first chamber, is connected to the latter via a large-area opening through which the coated objects can be lowered, and contains an inert gas atmosphere whose density is greater than that of the outer normal atmosphere. is phäre. A third lock chamber is in turn above the second lock chamber approximately at the level of the first lock chamber and adjacent to this and is also connected to the second lock chamber via a large-area opening. It also contains an inert gas atmosphere and communicates with the inert gas atmosphere within the drying tunnel. The coated objects are guided through these lock chambers in the order listed. A similar, but from the now dried objects in the reverse direction traversed outlet lock area is located at the end of the drying tunnel.

Inert gases may in particular be nitrogen, CO ", noble gases or other gases in which the content of the

Dry adversely affecting noxious gas component is below a predetermined threshold. In the case of UV-curing paints used today, e.g. Oxygen is a noxious gas component, and its concentration should be below 1% by volume.

Although the inert gas losses can be kept relatively low in the above-mentioned construction, there is always a demand for further reducing the inert gas consumption in view of the cost of the inert gas.

The object of the present invention is to further develop a device of the type mentioned at the outset so that the inert gas consumption is further reduced with the least possible outlay on equipment.

This object is achieved in that

f) the gas exchange chambers of the inlet lock area and the outlet lock region optionally either with a pump, which can suck the atmosphere present in the gas exchange chambers and lead into the outside atmosphere or can be connected via a controllable valve directly to the outside atmosphere.

Thus, according to the invention, both gas exchange chambers of both lock areas can be so well freed of normal atmosphere with the aid of a vacuum pump that the atmosphere prevailing there after single inflow of the inert gas receives the quality prescribed by the manufacturers of the paints. A multiple rinsing is not required; the time in which the atmosphere exchange can take place is considerably shortened compared with the prior art.

In this case, a reservoir for inert gas is expediently provided, which can be connected to the gas exchange chambers of both the inlet lock area and the outlet lock area. This reservoir can be used for the first time inerting both the gas exchange chambers of the two lock areas and the interior of the drying tunnel.

Particularly preferred is that embodiment of the invention in which the gas exchange chambers of the inlet lock area and the outlet lock area can be connected to each other via a connection path in which at least one pump is located so that inert gas can be pumped from one gas exchange chamber into the other gas exchange chamber , In this way, a lot of inert gas can be saved, since the inert gas, which are removed from the gas exchange chamber must, in order to allow normal atmosphere there, can be temporarily stored in the other gas exchange chamber.

If a direct connection path between the two gas exchange chambers can be produced, the inert gas can flow from one gas exchange chamber into the other gas exchange chamber until a same pressure is established in both gas exchange chambers without a pump. The pumping action therefore only needs to start after a pressure equalization has taken place.

When a buffer is connectable to the two gas exchange chambers, the inlet sluice area and the outlet sluice area can be operated independently of each other, and yet inert gas can be displaced in its entirety between the gas exchange chambers.

If a harmful gas sensor is provided in the line system of the device, changes in the concentration of harmful gas can be monitored.

It is then possible to add so much pure inert gas to the supplied gas that overall the maximum permissible pollutant gas concentration has not been reached.

If one looks at the pollutant gas sensor in the intake line or the outlet line of the pump, a single pollutant gas sensor is sufficient to determine information about the pollutant gas concentration in different subregions of the device.

The noxious gas sensor also makes it possible to supply gas quantities which no longer meet the strict requirements for the operation of the device, but which still contain significantly less noxious gas than the ambient atmosphere. - S -

for rinsing purposes in a purge gas container, the contents of which are usable in initial cycles of initial inerting.

An embodiment of the invention will be explained below with reference to the drawing. Show it

Figure 1 shows a vertical section through a section of a paint shop for vehicle bodies with schematically illustrated peripheral devices;

2 shows schematically the functional sequence during the passage of a vehicle body through the system of FIG. 1.

First, reference is made to FIG. In this, a section of a painting system for vehicle bodies 10 is shown in vertical section, which carries the reference numeral 1 in total. This section comprises an inlet lock area 3 for a drying tunnel 4, the drying tunnel 4 itself, which is only partially shown, and an outlet lock area 5. The vehicle bodies 10, in the direction of the arrow 6 in FIG not shown paint booth coming through the inlet lock area 3, the drying tunnel 4 and the outlet lock area 5 moves, which is carried out cyclically, at least in the lock areas 3, 5. In detail, conveyor systems 7, 8, 9 which are not explained in greater detail are used, which are known to the person skilled in the art.

In the paint booth are in a known manner application devices with which automatically or by hand on the vehicle bodies 10th Lacquer can be applied. The paint booth in turn are preceded by other pretreatment stations that correspond to the state of the art.

The illustrated section of the painting 1 downstream of a conventional cooling zone.

The drying tunnel 4 is also built according to the state of the art and contains suitable heating and irradiation facilities with which the applied paint can be dried or hardened.

While there is an oxygen-containing "normal atmosphere" in the paint booth preceded by the drying tunnel 4 and in the cooler following the drying tunnel 4, there is an inert gas atmosphere inside the drying tunnel 4 which contains, for example, nitrogen and / or CO ".

In the present context, essentially only the inlet lock area 3 and the outlet lock area 5 are of interest, with which the two named atmospheres are kept separated during the passage of the vehicle bodies 10 in such a way that the least possible loss of inert gases takes place.

First, the entrance lock area 3 will be described. This is designed as a vacuum lock and comprises a gas exchange chamber 16, which can be closed at its two opposite end faces in each case by a motor-driven lift gate 24 and 25 respectively. The top wall of the gas exchange chamber 16 of the vacuum lock 3 is pierced by an exchange line 17 and by an outlet line 18. In the latter is a motor-operated valve 19th The outlet lock area 5 is designed in the same way, ie also as a vacuum lock. This vacuum lock also comprises a gas exchange space 31, and two motor-operated lift gates 32 and 33 arranged on the end side of the gas exchange chamber. Its cover wall is pierced in the same way as in the first vacuum lock 3 by an exchange line 30 and an outlet line 29. In the latter is again a motor-operated valve 28th

If necessary, the two outlet lines 18 and 29 lead via a chimney to the outside atmosphere.

The two exchange lines 17, 30 are each connected via a motor-operated valve 26 and 27 with a reservoir 34 for fresh, high purity inert gas. The two valves 26 and 27 can be bypassed via two parallel lying lines 35 and 36, in which in each case two motor-operated valves 37, 38 and 39, 40 are located. The two lines 35 and 36 are connected at points which lie between the two lying in the lines valves 37, 38 and 39, 40, respectively, by another line 41, in which a pump 42 is located. The line 41 leads via the line 36 in Figure 1 upwards to a motor-operated valve 43 and from there optionally via a chimney to the outside atmosphere.

Before the plant 1 can be put into operation, a so-called "initial inerting" of the drying tunnel 4 must take place. This is to be understood that the normal atmosphere, which is initially located in the drying tunnel 4, must be replaced by an inert gas atmosphere that meets the requirements of the paint manufacturer. This means that the oxygen content in the atmosphere, which prevails in the drying tunnel 4, must be lowered below a predetermined limit, which may be, for example, one percent by volume.

This initial inerting can be carried out with the aid of one of the two vacuum locks 3, 5 in the following manner, with the input vacuum lock 3 being selected as an example.

First, the gates 24, 25 and 32 are closed. Likewise, the valves 19, 26, 38, 39 and 40. Now, by means of the pump 42 via the lines 17, 35 and

41 evacuated with open valve 43, the gas exchange chamber 16 of the vacuum lock 3. Then the valve

37 closed and the valve 26 is opened, so that the gas exchange chamber 16 of the vacuum lock 3 can fill from the reservoir 34 with pure inert gas to atmospheric pressure.

Now, the gate 25 between the gas exchange chamber 16 and the drying tunnel 4 is opened, so that the atmospheres therein can mix. The gate 25 is closed and the gas exchange chamber 16 in turn via the above-described way by means of the pump

42 evacuated with the valve 43 open.

This process is repeated until the required inert gas atmosphere prevails within the drying tunnel.

The passage of vehicle bodies 10 through the installation 1 after completed initial inerting can be carried out in a manner which will be described below with additional reference to FIG. In this figure 2 are spaces with the normal atmosphere (Ambient air) are filled, with a cross hatch and spaces filled with inert gas atmosphere, characterized by simple hatching. Rooms that are evacuated do not have hatching in FIG. The bodies are represented by rectangles.

In the type of operation according to FIG. 2, inert gas oscillates between inlet vacuum lock 3 and outlet vacuum lock 5.

As a starting point, it is assumed according to panel A that a painted vehicle body 10 to be dried stands in front of the closed inlet vacuum lock 3, which is filled with normal atmosphere. The outlet vacuum lock 5 is also closed, and in it is inert gas atmosphere

Passing through a vehicle body 10 begins according to part B so that the vehicle body is retracted into the inlet vacuum lock 3 with the lift gate 24 open, in the gas exchange chamber 16 of course normal pressure prevails at this time, which is the case for all opening and closing movements of gates , The lifting gate 25 is closed.

At the same time, a vehicle body with dried paint can be moved out of the continuous tunnel 4 with the lift gate 32 open into the outlet vacuum lock 5.

Now, according to part of image C, the inlet vacuum lock 3 evacuated by means of the pump 42 in the manner already described above and then according to part D in the manner already explained from the outlet vacuum lock 5 and possibly additionally from the reservoir 34 with Inert gas filled. Then, the lifting gate 25 is opened and the vehicle body 10 can enter the drying tunnel 4 (partial image E). The lifting gate 25 is closed again. The outlet vacuum lock 5 is simultaneously filled with normal atmosphere.

In the drying tunnel 4, the vehicle body 10 in the usual way with electromagnetic radiation and optionally applied heat (partial image F), whereby the coating in the above sense "dries". In this drying time, the lifting gate 33 is opened, the dried vehicle body 10 is extended and the lifting gate 33 is closed again. From this point on, the gas exchange chamber 31 of the outlet vacuum lock 5 is still filled with normal atmosphere; but it contains no vehicle body 10. The gates 32 and 33 are closed.

Now (Teibild G) the gas exchange chamber of the outlet vacuum lock 5 is evacuated by means of the pump 42 via the line 30, the line 35, the open valve 38 and the open valve 43.

The valves 37 and 38 are now opened, so that inert gas from the gas exchange chamber 16 of the inlet-vacuum lock

3 via the lines 17, 35 and 30 in the gas exchange space 31 of the outlet-vacuum lock 5 can flow. In this way, a pressure equalization in these two gas exchange chambers 16, 31 is achieved. Now the valve 39 is closed; the valves 37 and 40 are opened.

In this way, the pump 42 can suck the remaining, already reduced in pressure inert gas atmosphere from the gas exchange chamber 16 of the inlet vacuum lock 3 and via the line 17, the line 35 and the open valve 37, the line 41, the open valve 40th , the wires Pump 36 and 30 in the gas exchange chamber 31 of the outlet-vacuum lock 5 over. If necessary, the valve 27 is opened so far that a small amount of high-purity inert gas 34 is metered from the reservoir 34, which is sufficient to keep the oxygen content in the atmosphere of the gas exchange chamber 31 of the outlet-vacuum lock 5 below the permissible maximum value ,

At the same time, the gas exchange chamber 16 is evacuated and a new vehicle body to be dried is placed in front of the inlet vacuum lock 3.

Now you have reached the state shown in field H.

Now, with the valve 19 open, the gas exchange chamber 16 can be filled with normal atmosphere via the line 18 and the lifting gate 24 can be opened so that the inlet vacuum lock 3 is ready to receive another vehicle body 10. At the same time, the lifting gate 32 can be opened, so that subsequently the foremost vehicle body 10 located in the drying tunnel 4 can be retracted into the gas exchange space 31 of the outlet vacuum lock 5.

Now the state according to field A for the next

Cycle reached. These cycles are repeated as long as the plant 1 is in the drying operation.

In the procedure described above, the operation of the inlet vacuum lock 3 and the operation of the outlet

Vacuum lock 5 forcibly coupled by the fact that the inert gas was replaced directly between them. The operation of the two locks can be made independent of each other by placing the inert gas in a large buffer (eg a balloon) under atmospheric pressure Pressure caching, with both gas exchange chambers

* is connectable and indicated by dashed lines in FIG.

* indicates. In order to selectively connect the balloon 34 or the reservoir 34 (or both) with the lying between the valves 26 and 27 line section, two motor-operated valves 44 and 45 are provided.

As an alternative, for the same purpose, the inert gas withdrawn from a gas exchange chamber can, for the same purpose, be compressed or pushed back into the reservoir 34 in a rigid intermediate reservoir 34 having smaller dimensions.

Also you can make the initial inertization in flow, instead of as described above with oscillating

Gas movement. For this one can e.g. with open lifting gates 25, 32 and closed lifting gates 24, 33 and opened valves 37, 43 suction gas from the gas exchange chamber 16 and the flow tunnel 4 and at the same time supply inert gas with the valve 27 open.

Alternatively, one can analogously receive a flow in the drawing to the left to the right by appropriate control of the valves 26, 38, 43 in their open position.

In a further modification of the invention, an oxygen sensor 46 can be connected in the intake path of the pump 42 (or its outlet line), which provides an output signal corresponding to the oxygen content in the intake gas. The oxygen sensor 46 may, for. Example, be a sensor that responds to the infrared absorption bands of oxygen molecules. Alternatively, it may be a solid oxygen sensor. At the output of the pump 42, a purge gas container 48 is connected via a further motor-operated valve 47. This is further connected via a further motor-operated valve 49 with the exchange line 17 and thus the gas exchange chamber 16.

The supplemented system can now work as follows:

If the oxygen sensor 46 determines that the oxygen content in the aspirated gas mixture is greater than the predetermined limit value, it causes a controller 50 of the system to open the valve 26 or 27 so much that in the just used for supplying inert gas the exchange lines 17, 30 again falls below the limit for oxygen.

Does the pump 42 from a gas from one of the locks, without this again one of the exchange lines 17, 30 is supplied, and the oxygen concentration is below a further limit, which is above the already mentioned maximum oxygen concentration, but still below another oxygen limit, which is still useful for the initial inerting, in order to reduce the high oxygen content in air-filled spaces of the plant, so opens the control

50, the motor-operated valve 47 so that the oxygen-depleted gas still useful for rinsing purposes is pressed into the rinsing gas container 48. In the initial inertization, the purge gas can then be supplied from there by opening the valve 49 of the exchange line 17 when the

Initial inerting via inert gas supply to the lock area 3 takes place.

Optionally, the purge gas container 48 via the valve 49 corresponding further valve with the Exchange line 30 are connected.

If the controller 50 determines that the oxygen concentration in the gas sucked by the pump 42 is so high in accordance with the output signal of the oxygen sensor 46 that this gas is no longer usable for flushing purposes, the controller 50 opens the valve 43, so that this gas leaves the plant.

It is understood that it is also possible to use a plurality of rinsing gas containers which contain purge gas having different amounts of residual oxygen and are connected via separate valves 47 to the output of the pump 42, which is then controlled by the controller 50 in accordance with the current value of the oxygen concentration in the inerting phase sucked gas are opened differently, and be connected by the control circuit 50 according to the progress of the inerting sierungsvorganges via separate valves 49 differently with one of the exchange lines.

Claims

claims

1. Device for drying objects, in particular of painted vehicle bodies, with

b) an inlet-lock area, which is connected upstream of the drying tunnel, comprises at least one gas exchange chamber and separates the inert gas atmosphere prevailing inside the drying tunnel from the outer normal gas atmosphere;

c) an outlet lock area, which is connected downstream of the drying tunnel, comprises at least one gas exchange chamber and separates the inert gas atmosphere prevailing inside the drying tunnel from the outer normal atmosphere;

e) an inert gas storage tank connectable to the gas exchange chambers of the inlet lock area and the outlet lock area;

characterized in that

f) the gas exchange chambers (16, 31) of the inlet lock area (3) and the outlet lock area (5) optionally either with a pump (42), which aspirate the atmosphere present in the gas exchange chambers (16, 31) and convey it into the outside atmosphere, or they can be connected directly to the outside atmosphere via a controllable valve (19, 28).

2. Apparatus according to claim 1, characterized in that a storage container (34) is provided for inert gas, which can be connected to the gas exchange chambers (16, 31) both of the inlet lock area (3) and the outlet lock area (5) ,

3. Apparatus according to claim 1 or 2, characterized in that the gas exchange chambers (16, 31) of the inlet lock area (3) and the outlet lock senbereiches (5) via a connecting path (17, 30, 35, 36) in the at least one pump (42) is connected to each other such that inert gas from a gas exchange chamber (16, 31) in the other gas exchange chamber (31, 16) can be pumped.

4. Apparatus according to claim 3, characterized in that a direct connection path (17, 36, 30) between the two gas exchange chambers (16, 31) can be produced, via which a pressure equalization between the two gas exchange chambers (16, 21) can take place.

5. Device according to one of claims 1 to 4, characterized

* characterized in that a buffer (34) with the two gas exchange chambers (16, 31) is connectable.

6. Device according to one of claims 1 to 4, characterized in that in a section of their

Gas-flow lines (17, 30, 35, 36, 41) a Schadgassensor (46) is arranged, preferably in the intake or the outlet line of the pump (42).

7. The device according to claim 6, characterized in that at the output of the pump (42) via a motor-actuated valve (47) at least one purge gas container (48) is connected, via a second motor-operated valve (49) with an exchange line ( 17) leading to one (3) of the lock areas (3, 5).