EP0985121B1 - Device for exposing a substrate to uv rays and method for using this device - Google Patents

Abstract

The invention relates to a device comprising a UV lamp (2) which is accommodated in a housing (3) in such a way that UV rays emerge directly or indirectly from an exit (4), and strike a substrate (1) which is to be exposed to the rays. The lamp is air-cooled in a closed circuit, whereby the air enters the housing through an air inlet (6) and leaves the housing again through an air outlet (7). The exit (4) is sealed with a glass plate transparent to UV, so that neither cooling air nor ozone can exit directly from the housing. This also protects the lamp and the reflector surrounding the lamp from being dirtied by the suctioned cooling air.

Description

The invention relates to a device for irradiating a Substrate by means of UV rays according to the preamble of Claim 1. Such a device is from the US-A-4 182 047 known. Such devices are for example in printing technology for drying paints, inks, etc. Polymerization used. Treatments using UV rays but are also used, for example, in food technology used for preservation purposes etc.

A problem with UV radiation sources is that in addition to UV radiation, a very high proportion of heat-intensive Infrared radiation is emitted. On the one hand, this requires permanent cooling of the radiation source and on the other hand Measures have to be taken so that it is mostly heat-sensitive Substrate cannot be damaged. to Cooling of the UV radiation source was therefore already known an air flow through that closed with a quartz glass plate To lead housing.

For example, US-A-5,094,010 shows a generic comparable UV lamp, its housing additionally is also equipped with water cooling. The reflector The UV lamp is solid in a relatively massive Integrated lamp head. This UV lamp is for drying large workpieces such as Boat hull made of glass fiber reinforced Plastic determines and is not suitable for irradiation of substrates moving at high speed on the Radiation source passing by. A quick fade or The radiation source cannot be turned away.

DE U 93 12 809.6 is a UV radiation device described for highly productive production lines, for example is intended for the production of compact discs. The Outlet opening is covered with a quartz glass pane, however, the housing is not hermetic to the environment completed. Ambient air is created via an exhaust air device sucked in through side ventilation openings and slots. This has the disadvantage that dirt and dust particles in the housing can reach. The reflector of the UV lamp is in two movably mounted reflector halves divided for dimming the radiation collapses overlapping each other can be. Despite the air cooling, the reflector halves exposed to very high temperatures when closed and the heat rays are also thrown back onto the lamp.

In GB A 2 258 296 the open side of the reflector is opposite the environment by several parallel to each other Tubes, preferably made of quartz glass. Through this Pipes themselves, as well as through the casing, can generate a flow of cooling gas be directed. To stop the rigidly mounted UV lamp a special aperture device is provided.

Finally, through US A 4 182 047 is a UV radiation unit became known at the over the open side of the reflector cooling air can be sucked in. The reflector is housed in a housing that is a total of Swivel axis from a working position to a safety position is pivotable, in which the substrate is not acted upon becomes. The cooling function is maintained in both positions

There is a major disadvantage of open airflow cooling in that the intake cooling air contaminants such as Carries dust or fine paint particles. These impurities hit the surface of the UV lamp or reflector, where they are burned in due to the high temperature and form a film of dirt over time. This reduces the efficiency the radiation source.

On the other hand, the known devices with closed Cooling air system does not work in different operating positions and the very sensitive reflectors are only on one Side exposed to the cooling air flow.

It is therefore an object of the invention to provide a device to create the type mentioned, in which the UV lamp without the risk of contamination can be cooled using cooling gas can. Cooling should also be possible with a movable housing in such a way that not only the UV lamp itself, but the reflector is also cooled sufficiently. This task will solved according to the invention with a device which has the features in claim 1.

Closing the exit side with a UV-transparent Glass plate in particular with a quartz glass plate allows a closed inside the lamp housing Lead cooling air circuit. For this purpose the housing is with at least one cooling gas inlet and at least one each Provide cooling gas outlet, in such a way that the UV lamp with the gas flow between the inlet and outlet can be acted upon. Cooling with full power is therefore in every operating position possible without the environment being affected by a current becomes. In addition, ozone can no longer be applied to the lamp escape. So there is no longer any risk that the The surface of the substrate is directly exposed to air containing ozone becomes what in certain cases the one with the UV rays can delay the desired drying.

To compensate for the relative movement of the housing between the Working position and stand-by position are the supply line and the discharge line at least in sections as flexible Lines or designed as telescopic tubes. The housing forms in this way an autonomous module that is independent of its Operating position in a closed system with a cooling gas flow can be applied. The housing is between the working position and the stand-by position can be moved linearly stored.

The reflector is so freely stored in the housing that it Cooling gas flows around in every operating position.

A particularly high degree of efficiency can be achieved if the Cooling gas inlet with a pressure fan and when the cooling gas outlet is connected to a suction fan. In this way can flow through large amounts of cooling gas with a specific flow the lamp housing are guided. Harmful ozone is extracted. Alternatively, it is of course also conceivable that only the cooling gas inlet with a pressure fan or that only the cooling gas outlet is connected to a suction fan.

Particularly efficient cooling can be achieved that a temperature sensor is arranged in the housing and that control means on the pressure fan and / or on the suction fan arranged to control the amount of air flowing through the housing which are operatively connected to the temperature sensor. The amount of cooling gas can thus be controlled via the temperature sensor become. This can be achieved, for example, if the Control means a motorized flap for changing of the flow cross-section. The fan drive motor therefore always works at full power, so without Delay can be worked with maximum cooling capacity can. Alternatively, the control means can also use frequency control for the drive motor of the pressure fan and / or the suction fan.

It is particularly advantageous if the cooling gas outlet or a connected to this outlet line with an ozone filter is. This makes the contamination of the environment artificial generated ozone prevented. The air cleaned in this way can a suitable place in the room for heating purposes because they have temperatures of up to 80 ° Celsius can. It is also conceivable to feed the heated exhaust air in a heat exchanger for the recovery of the discharged Warmth.

In certain cases it is also appropriate if the cooling gas inlet or an inlet line connected to it Air filter is provided. The cooling gas entering the housing is cleaned of dust and contamination of the UV lamp will be prevented.

The UV lamp in the housing is preferably surrounded by a reflector, who with at least one opening for passing the Air flow is provided. This can be advantageous lying on the plane of symmetry of the reflector and parallel act on the longitudinal slot extending to the UV lamp. This can at least part of the amount of cooling gas is aimed directly at the UV lamp become.

A reflector with or without an opening can also be transparent to heat radiation be trained. As a result, the reflector reflects only the UV rays, while a large part of the heat-intensive IR radiation penetrates the reflector. A such design of the reflector can be in the management of Cooling gas within the housing are specifically considered. The reflector particularly advantageously consists of a glass ceramic (e.g. ROBAX® registered Brand). Glass ceramic materials have a very high Permeability to heat rays and are used for this purpose also used for electric hot plates. By known Coating techniques can be applied to a mirror layer so that UV rays are still reflected.

In addition to the housing, an absorber for absorption is advantageous the heat and UV rays are arranged in the stand-by position. The absorber can be used for additional cooling with a suction device be connected.

If the substrate run is temporarily stopped the housing is automatically moved to the stand-by position, so that the substrate does not have an excessively long exposure to radiation exposed, which in extreme cases leads to spontaneous combustion could lead. The UV rays are from the absorber absorbed so that the operating personnel is not at risk.

The maximum possible extension position of the housing to reach the working position can be adjustable in such a way that the UV lamp irradiated only a portion of the substrate while the remaining section is directed towards the absorber and irradiated this. The adjustable extension position has the advantage that the radiation section is the size of the continuous Workpiece can be adjusted. This way not unnecessarily irradiated means of transport or the like which would warm up. Particularly advantageous the housing can be moved linearly if it is connected to at least one Guide rail is suspended and if it is with a pneumatic cylinder between the working position and the stand-by position is movable. Other drive means, such as linear motors etc. would of course also be conceivable.

The housing is advantageously divided into a first flow chamber, in which the UV lamp is arranged and in one second flow chamber, the cooling gas inlet at the first Flow chamber and the cooling gas outlet on the second flow chamber is arranged. The two flow chambers are over one slit running parallel to the UV lamp or via a Row of openings connected together.

The quartz glass plate has a different coefficient of thermal expansion than the steel case. It is therefore advantageous in stored in a dilatation bearing on the housing.

The invention also relates to a method for operating the device mentioned at the beginning. This method is characterized by the features in claims 13, 14 and 15. Feeding the cooling gas at a pressure of at least 1 kilopascal causes intensive cooling of all parts within the housing. The working pressure on the pressure fan can be 2 to 3 kilopascals. The pressure difference compared to the housing results from the transmission lines. Depending on the size of the housing, the cooling gas throughput can be up to approx. 400 m ³ / hour. The temperature of the cooling gas fed in can correspond to the ambient temperature, but should not exceed approx. 25 to 30 ° Celsius. In certain cases it would be conceivable to reduce the temperature of the cooling gas fed in with a cooling unit. The temperature of the exhaust air at the outlet can be 45 to 80 ° Celsius, so that heat recovery makes sense in certain cases.

In certain circumstances, it can be beneficial in the case always maintain a pressure below atmospheric pressure. This ensures that there is no ozone Air can escape from the housing.

The problem of ozone formation due to the interaction of UV rays and atmospheric oxygen could also be completely eliminated as a result that nitrogen is used as the cooling gas. It has it has also surprisingly been shown that the polymerization process works better in a nitrogen atmosphere and it would therefore conceivable to irradiate the substrate in a nitrogen atmosphere and the gas simultaneously as cooling gas through the housing respectively.

Figur 1

die Seitenansicht eines linear verschiebbaren Bestrahlungskopfes mit den Merkmalen der Erfindung,

Figur 2

ein Querschnitt durch ein Lampengehäuse mit Reflektor,

Figur 3

die schematische Darstellung einer Kühlluftsteuerung,

Figur 4

ein Querschnitt durch ein Lampengehäuse mit schwenkbarer UV-Lampe,

Figur 5

ein Querschnitt durch ein Lampengehäuse für direkte und indirekte Bestrahlung des Substrats,

Figur 6

eine Seitenansicht eines linear verschiebbaren Bestrahlungskopfes analog zu Figur 1, aber mit weiteren konstruktiven Details,

Figur 7

eine Draufsicht auf den Bestrahlungskopf gemäss Figur 6,

Figur 8

eine Stirnansicht auf dem Bestrahlungskopf gemäss Figur 6 in etwas vergrössertem Massstab, und

Figur 9

ein Dilatationslager für die Quarzglasplatte.

Embodiments of the invention are shown in the drawings and are described in more detail below. Show it:

Figure 1

the side view of a linearly displaceable radiation head with the features of the invention,

Figure 2

a cross section through a lamp housing with reflector,

Figure 3

the schematic representation of a cooling air control,

Figure 4

a cross section through a lamp housing with pivotable UV lamp,

Figure 5

a cross section through a lamp housing for direct and indirect irradiation of the substrate,

Figure 6

2 shows a side view of a linearly displaceable radiation head analogous to FIG. 1, but with further structural details,

Figure 7

6 shows a top view of the radiation head according to FIG. 6,

Figure 8

a front view of the radiation head according to Figure 6 on a somewhat enlarged scale, and

Figure 9

a dilatation bearing for the quartz glass plate.

In all of the exemplary embodiments described below ambient air is used as the cooling gas. The simplicity therefore the term "air" is always used instead of "Cooling gas" used.

1 shows a highly schematized UV lamp 2, which is arranged in a housing 3. By a Exit side 4 on the housing hit the UV rays Substrate 1, for example on a conveyor belt under the Housing is passed through.

The exit side 4 on the housing 3 is UV-transparent Quartz glass plate 5 closed. Until an air inlet 6 and an air outlet 7 that is Housing 3 is thus largely hermetically sealed. The Air inlet 6 is connected to a pressure fan 8 which Ambient air is sucked in and at a relatively high pressure Housing 3 feeds. The air outlet 7 is with a suction fan 9 connected, which sucks air from the housing and releases in turn to the environment via an ozone filter 12. The Feed line 10 and the discharge line 11 are preferred designed as flexible lines. Air inlet 6 and air outlet 7 are arranged on the housing such that the UV lamp 2 lies in the main flow area. Of course can additional baffles, baffles and the like be arranged to the flow effect improve. The housing 3 is not closer to one here shown carriage attached to a linear guide 14 and can be moved in the direction of arrow a. From the shown working position can thus be unchanged Performance of the fans 8, 9 the housing as far as in the Illustration to the right until the UV lamp 2 lies above the absorber 13. In this stand-by position temporarily the throughput of the substrates 1 can be stopped. In this way, switching off the UV lamp 2 can be avoided become.

A cross section is also highly schematized in FIG represented by the housing 3, the outlet side 4 with a quartz glass plate 5 is closed. The UV lamp 2 is surrounded by a reflector 15, one above the UV lamp 2 Gap 16 has. Through this gap, cooling air from the Hit the air inlet 6 directly on the UV lamp 2. On Part of the cooling air spreads on the back of the reflector 15 along and also cools it. The air outlet 7 is arranged on the long side, but could just like the Air intake is also on one end. Of course could also have multiple air intakes in each embodiment or air outlets on the housing.

The reflector 15 is by means of a surface coating formed such that only the UV rays 21 reflect be, while heat-intensive IR rays 22 den Penetrate reflector directly. This measure also serves to keep harmful heat rays away from the substrate.

Figure 3 shows schematically a lamp housing 3 with one in it arranged UV lamp 2. There is also a temperature sensor in the housing 19 attached, with the help of the internal temperature can be constantly monitored. The temperature sensor 19 is in operative connection with an actuator 20 with which Flap valves 18, 18 'in the feed line 10 or in the Discharge line 11 can be operated. The drive motors 17, 17 'of the pressure fan 8 or the suction fan 9 always work with full power and control the air volume is only via the flap valves. Alternatively, the drive motors 17, 17 'could also be used a frequency control, which control pulses receives from the temperature sensor 19.

Figure 4 shows a lamp housing 3, in which the arranged therein UV lamp 2 together with its reflector 15 pivoted through 90 ° can be. In the working position shown, the UV rays through the quartz glass plate 5 on the exit side 4 out. In the standby position shown at 15 ' of the reflector, the rays hit a mudguard 23.

Of course, alternative working positions would also be or stand-by positions conceivable in which the UV rays via a partially transparent mirror onto the substrate or be directed away from the substrate. Such embodiments are e.g. in CH-A-660 489. The partially permeable Mirror can be fixed or swiveling in the Housing be arranged.

Figure 5 shows a UV lamp in which two different Operating positions are possible. In the housing 3 with the through a quartz glass plate 5 are closed outlet side 4 several air inlets 6, 6 ', 6' 'and several air outlets 7, 7 'arranged. The UV lamp 2 is provided with a reflector 15, which can be turned into three different positions can. Next to the UV lamp is a partially transparent mirror 24 arranged over which in a first operating position UV rays 21 can be directed onto the substrate 1, while the heat intensive IR rays 22 penetrate the mirror and absorbed on the absorber 13. In a second Operating position, the reflector 15 can be 90 ° in this way that the radiation is swung directly through the glass plate 5 falls on a substrate 1. This direct radiation contains the entire spectrum of rays, including the IR rays, however, which may be desirable in certain cases. In the stand-by position, the reflector 15 is turned upwards, so that the rays fall on the fender 23. On Such a multifunctional radiation head is air cooling particularly advantageous in a closed housing because through the quartz glass plate 5 the mechanically moving parts and in particular also the sensitive mirror 24 is protected become. The cooling air can be targeted within the housing the points are directed where it is needed, e.g. also on the absorber 13.

Of course, additional cooling measures can be taken on the housing be provided without the object would leave the invention. So it would be e.g. conceivable that additionally cooling channels for the passage of a cooling liquid are provided.

Figures 6 to 8 show an irradiation head, which also is linearly displaceable in the direction of arrow a. The shift takes place on a frame 25, the Can be part of an irradiation device. To For this purpose, roller bearings 26 are arranged on the frame, which in two U-shaped guide rails 27 on the top of the Intervene in housing 3. Between the two guide rails a pneumatic cylinder 28 is attached, the piston rod is connected to the frame at a piston attachment 37. The pneumatic cylinder is not supplied via here Pneumatic lines shown. In Figure 6 that is complete extended position shown so that the UV lamp 2 down the entire length of the substrate radiates.

About limiting means not shown here, such as e.g. plug-in stop bolts or the like, the maximum possible extension position can be limited. Such Limitation, for example, causes the face of the radiation head only down to the vertical plane 36 extending. In this position, the UV lamp 2 only transmits part of their length down radiation. The rest Section of the lamp partially overlaps the one below the housing 3 arranged absorber 13. This consists of grill-like slats and can become intense radiation Heat to red heat. In the withdrawn stand-by Position, the UV lamp 2 irradiates the absorber via its whole length.

In the present case, the substrate is a cylindrical one Bottle cap 35 shown on the end a mandrel 34 is attached. With a complete Extending the UV lamp 2 would obviously also be a Part of the mandrel 34 irradiated and thus heated. Since the mandrel 34 is not cooled, this could damage the Guide cap 35. When extending to the extended position 36, on the other hand, practically only the cap 35 irradiated.

The housing 3 is in a first flow chamber 29 and second flow chamber 30 divided. Serve as a subdivision separating plates 31 having a longitudinal slot 32 in the middle leave open. This longitudinal slot runs over the longitudinal slot 16, which form the two reflector halves. The Cooling air enters through the supply line 10 in the front a first flow chamber 29, flows around the UV lamp 2 and their reflector 15 and then arrives in the direction of arrow b in the second flow chamber 30, which they also face leaves again via the discharge line 11. The lines 10 and 11 are designed as flexible hose lines. This also applies to the absorber suction line 33, via which Ambient air through the absorber grill for cooling purposes is suctioned off. The electrical lines leading to the UV lamp 2 or lead to the temperature sensor 19 are also summarized in a flexible hose 40.

FIG. 9 shows a dilatation bearing 38 for holding the Quartz glass plate 5. This is by means of a bracket 39 attached to the housing 3 such that they are in the direction of the arrow c can expand. The bracket 39 may be the quartz glass plate do not jam. Rather, it has proven to be beneficial proved that the quartz glass plate with sufficient Free play rests in the bracket 39 (dash-dotted Position). Will be in the housing opposite the atmosphere Maintaining negative pressure, the quartz glass plate is sucked in and presses tightly against the housing opening (hatched position). Use would also be conceivable high temperature resistant sliding seals.

Claims (15)

1. Apparatus for irradiating a substrate (1) by means of ultraviolet rays, having a UV lamp (2) which is arranged in a housing (3) in such a manner that ultraviolet rays exit the housing directly or indirectly on one exit face (4), and having means for cooling the UV lamp by a stream of cooling gas, the housing (3) incorporating at least one respective cooling gas inlet (6) and at least one respective cooling gas outlet (7), thereby enabling cooling gas to be conducted through the housing, the entire housing (3) being adapted to be moved between an operating position in which the ultraviolet rays strike the substrate and a stand-by position in which the ultraviolet rays are deflected away by the substrate, and the UV lamp (2) incorporating a reflector (15) around which cooling gas flows on all sides in the housing (3) in the operating position and in the stand-by position, characterised in that

   the exit face (4) is sealed with a glass slab (5) which is permeable to UV radiation,

   the housing (3) is mounted so as to be linearly displaceable between the operating position and the stand-by position,

   and the cooling gas inlet (6) is connected up to a feeder line (10) and the cooling gas outlet (7) to a take-off line (11),

   a feeder line and a take-off line being respectively connected up to the cooling gas inlet and the cooling gas outlet, at least sections of which are in the form of flexible lines or telescoping tubes in order to compensate for the relative situation of the operating position and the stand-by position.
2. Apparatus according to claim 1, characterised in that the feeder line (10) is joined to a fresh air ventilator (8) and/or the take-off line (11) to an exhauster (9), that a temperature sensor (19) is arranged in the housing (3), and that arranged on the fresh air ventilator (8) and/or on the exhauster (9) are control means for controlling the quantity of air that flows through the housing, which means are operatively connected to the temperature sensor.
3. Apparatus according to claim 2, characterised in that the control means incorporate a motor-driven butterfly valve (18, 18') for varying the flow cross-section.
4. Apparatus according to claim 2, characterised in that the control means incorporate a frequency control for the driving motor (17, 17') of the fresh air ventilator and/or of the exhauster.
5. Apparatus according to any of claims 1 to 4, characterised in that on its plane of symmetry and parallel to the UV lamp the reflector (15) incorporates a lengthways slot (16) for conducting the stream of cooling gas through.
6. Apparatus according to any of claims 1 to 5, characterised in that the reflector (15) is configured so as to let thermal radiation through.
7. Apparatus according to claim 6, characterised in that the reflector (15) consists of a glass-ceramic provided with a reflective coating.
8. Apparatus according to any of claims 1 to 7, characterised in that arranged alongside the housing is an absorber (13) for absorbing the thermal and ultraviolet radiation in the stand-by position, and that a suction device is arranged on the absorber for additional cooling.
9. Apparatus according to claim 8, characterised in that the maximum position by which it is possible to extend the housing (3) in order to reach the operating position can be adjusted in such a way that only one section of the UV lamp (2) irradiates the substrate, while the remaining section irradiates the absorber.
10. Apparatus according to any of claims 1 to 9, characterised in that the housing (3) is suspended on at least one guide rail (27) and is adapted to be moved between the operating position and the stand-by position by a pneumatic cyinder (28).
11. Apparatus according to any of claims 1 to 10, characterised in that the housing (3) is divided into a first flow chamber (29), in which the UV lamp (2) is arranged, and into a second flow chamber (30), and that the cooling gas inlet (6) is arranged on the first flow chamber (29) and the cooling gas outlet (7) is arranged on the second flow chamber (30), the two flow chambers being connected to one another via a slot (32) which runs parallel to the UV lamp (2) or over a row of apertures.
12. Apparatus according to any of claims 1 to 11, characterised in that the quartz glass slab (5) is mounted in a dilatation bearing (38) on the housing in such a manner that temperature-governed expansions in the plane thereof can be compensated.
13. Method for operating the apparatus according to any of claims 1 to 12, characterised in that cooling gas at a pressure of not less than one kilopascal is fed into the housing (3) via the cooling gas inlet (6).
14. Method for operating the apparatus according to any of claims 1 to 12, characterised in that a pressure below atmospheric pressure is maintained in the housing.
15. Method for operating the apparatus according to any of claims 1 to 12, characterised in that nitrogen is used as the cooling gas.

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