WO2002013976A1

WO2002013976A1 - Device for applying a coating liquid on a metal sheet

Info

Publication number: WO2002013976A1
Application number: PCT/BE2001/000138
Authority: WO
Inventors: Jean Schrynemackers; Erwin Volon
Original assignee: Recherche Et Developpement Du Groupe Cockerill Sambre
Priority date: 2000-08-17
Filing date: 2001-08-17
Publication date: 2002-02-21
Also published as: ATE294645T1; EP1309410B1; DE60110607D1; BE1013647A3; ES2240498T3; DE60110607T2; PT1309410E; AU2001283721A1; EP1309410A1; DK1309410T3

Abstract

The invention concerns a device for applying a coating liquid on a metal sheet comprising a lower shell (33) forming a recuperating container and an upper shell (34) mutually mobile between a closed position wherein they form a closed chamber containing feeding means, a collecting cylinder (3) and transfer means and an open position wherein they are spaced apart from each other, a container of cleaning liquid reserve (53), a container of coating liquid reserve (36), a compressed air source (47), first circulating means capable of supplying to the feeding means, in open position of the chamber, coating liquid from a coating liquid reserve container (36), second circulating means capable of supplying, in closed position of the chamber, a cleaning liquid from a cleaning liquid reserve container (53), and spraying means (39) capable of spraying cleaning liquid through at least one of the two shells to wash the elements contained in the chamber in closed position.

Description

"Device for applying coating liquid to a sheet."

The present invention relates to a device for applying coating liquid to a sheet, comprising a rotary support cylinder around which a sheet continuously runs, - means for supplying coating liquid, a film collecting cylinder liquid, rotary, supplied by the supply means, and possibly means for transferring the liquid film from the collecting cylinder to the sheet moving around the support cylinder. Devices for coating liquid paint have been known for a long time on moving sheets. Commonly, a tank is used, called an inkwell, from which a rubberized cylinder takes paint and then transfers it to one or more successive cylinders, the last being a coating cylinder which applies the paint to the metal strip which runs and which rests itself on a large support cylinder

(see for example US-A-4,046,931).

The cleaning of these coating liquid application devices is necessary regularly. It is very complex, requires a lot of time and the consumption of detergent is very high. In addition, this cleaning is currently generally carried out manually and it has the disadvantage of being a risky operation for the workforce, given the toxicity of gaseous fumes and their danger of ignition. The present invention aims to solve these problems and to develop a device for overcoming the aforementioned drawbacks.

Advantageously, the device must be able to be cleaned quickly and efficiently.

These problems are solved by a device as described at the start, this device further comprising a washing device comprising

a lower shell forming a recovery container and an upper shell mutually movable between a closed position in which they form a closed enclosure containing the supply means, the collecting cylinder and the transfer means and an open position in which they are separated from each other, - a cleaning liquid reserve container, a coating liquid reserve container,

- a source of compressed air,

- first circulation means which are capable of supplying the supply means, in the open position of the enclosure, with coating liquid from the coating liquid reserve container, second circulation means which are capable of supplying to the means for supplying, in the closed position of the enclosure, the cleaning liquid from the cleaning liquid reserve container, projection means which are capable of projecting cleaning liquid through at least one of the two shells to wash the elements enclosed by the enclosure in the closed position, and optionally means for injecting compressed gas through at least one of the two shells to dry the elements enclosed by the enclosure in the closed position.

The movement and operation of some or all of these means can be carried out manually or automatically.

This device allows a reduction in cleaning time, a reduction in the consumption of cleaning liquid, which is generally a solvent for the coating liquid, and greatly improved safety and hygiene since the vapors released by the solvent are confined in an enclosure. closed, from which they can be sucked in a common way.

According to a particular embodiment of the invention, the washing device comprises as first and second circulation means, a circulation pump and a circuit comprising a supply conduit for introducing either coating liquid or cleaning in the supply means and an outlet conduit for discharging either coating liquid or cleaning liquid from the recovery container. Advantageously, this exemplary device therefore comprises a single circuit both for supplying coating liquid and for cleaning the supply means.

According to an advantageous embodiment of the invention, the liquid projection means serve simultaneously as gas injection means. This device has a particularly simple and easy to handle arrangement.

Other embodiments of the device according to the invention are indicated in the appended claims.

Other details and particularities of the invention will emerge from the description given below without limitation and with reference to the accompanying drawings. Figures 1 and 2 schematically show alternative embodiments of devices for applying coating liquid to a sheet.

Figure 3 shows a detail of Figure 1. Figures 4 to 9 show an embodiment of the device according to the invention with cleaning device, at different successive stages of its use.

In Figure 1 there is shown an alternative embodiment of the device according to the invention very simple, which comprises a rotary support cylinder 1 around which continuously scrolls a metal sheet or strip 2. The pressed strip 2 passes through the air gap adjustable, existing between the support cylinder 1 and a cylinder called collector 3, the peripheral surface of which is advantageously made of a rubbery material. The collecting cylinder 3 rotates in the opposite direction to the supporting cylinder 1. A supply container 4 containing coating liquid to be applied to the strip 2 is mounted opposite the collecting cylinder 3, so as to extend along this one.

This feed container 4 is shown in more detail in Figure 3, where, in the example illustrated, it is in the form of a feed chute of approximately prismatic shape. The chute 4 is open upwards and comprises a front wall 5 which is preferably parallel to the axis 6 of the collecting cylinder 3 and which extends approximately vertically. The chute further comprises a bottom wall 7 which extends obliquely upwards, from the bottom of the front wall 5, while forming at the lower corner of the chute thus formed, an outlet opening 8 for the liquid in the chute 4.

A flexible doctor blade 9 is, in the example illustrated, arranged in an adjustable manner on the bottom wall 7 so as to be able to extend more or less far towards the peripheral surface of the cylinder. manifold 3. To do this, in the example illustrated, the flexible doctor blade 9 is composed of several superimposed blades and each having an elongated opening which makes it possible to fix them in an adjustable manner on the bottom wall 7. For this purpose, we have provided in this example bolts 14, butterfly nuts 15 and plates also provided with an elongated hole. In this way it is possible to vary the distance between the blades of the doctor blade and the collecting cylinder, which will have the effect of causing these blades to flex more or less strongly and therefore to vary the pressure applied by the doctor blade and the amount of paint which can pass over the peripheral surface of cylinder 3.

The illustrated feed chute 4 also includes two side walls 18 and a rear wall 20.

The chute is mounted on a support bar 21, which is arranged so that it can rotate around its axis 22, using control means not shown. It is thus possible to adjust the outlet opening 8 by varying the inclination of the chute by a rotation thereof around the axis 22. This makes it possible to decrease or increase the pressure of the doctor blade on the collecting cylinder. 3 depending on the requested flow. All of these means therefore make it possible to apply the coating liquid to the collecting cylinder with a pressure which is perfectly determined according to the requirements, which makes it possible to avoid the problem of dewetting and to reduce the quantity of liquid required.

In the lower lateral corners of the trough 4 shown, one can provide two overflows, of which only one is shown and bears the reference 23. These overflows make it possible to evacuate by evacuation conduits any liquid overflowing in the overflows -pleins. These thus keep the liquid level inside a supply container constant. Deflectors 28 arranged on the bottom wall 7 distribute uniformly the coating liquid supplied by a supply conduit 30 in the upper part of the chute 4.

In this way, the coating liquid is always circulated in the chute, from top to bottom, in a uniform manner, at a speed adjusted precisely to the quantity of liquid having to pass through the flexible doctor blade. This makes it possible to reduce the quantity of liquid which is normally necessary when using an inkwell by approximately four times, while avoiding all the drawbacks linked to the impurities which circulate therein. The device is thus continuously supplied with a liquid, preferably filtered and maintained at the right temperature and viscosity.

As can be seen from FIG. 2, provision can also be made for the collecting cylinder to transfer the coating liquid to the strip 2 by means of one or more intermediate cylinders 31 and 32.

Other supply means than those provided in FIGS. 1 and 3 can also be envisaged by those skilled in the art. In the embodiment illustrated in FIG. 2, a conventional inkwell 27 has been shown. In broken lines, an embodiment has also been provided with an additional cylinder 29 bearing on the collecting cylinder 3, the coating liquid being supplied in the air gap between these two cylinders to form a meniscus from which the liquid is driven by gravity by the collecting cylinder 3.

As is apparent from Figures 4 to 9 the device according to the invention further comprises a washing device. This comprises a recovery container 33 which, in the example illustrated, has the shape of a shell. This shell 33 can for example recover any excess of coating liquid projecting laterally from the collecting cylinder, from the flexible doctor blade, or from the intermediate cylinders. A discharge conduit 34, provided with a valve 35, makes it possible to evacuate the liquid contained in the container 33 in a coating liquid reservoir 36, which allows recycling thereof (see FIGS. 4 and 9) or in a spent cleaning liquid tank 53 (see FIGS. 5 to 8).

The device illustrated in FIGS. 4 to 9 comprises a cleaning device comprising in addition to the lower shell 33

5 described above an upper shell 37. The upper shell is preferably provided with a vent pipe 38 for vapors and gases and spray nozzles 39 which can be connected to a flexible supply pipe 40 preferably provided a valve 41.

The shells are mutually displaceable in a known manner, not shown, and can therefore form in a close position a closed enclosure as shown for example in FIG. 5.

The supply duct 30, provided with a valve 42, is a flexible duct which is connected to the outlet of a circulation pump 43. The outlet of this pump 43 is also in communication with the flexible supply duct 40, by a pipe 44, provided at each of its two ends with a valve 45 and 46.

An air compressor 47 is also connected to the flexible supply duct 40 by a pipe 48 provided with a valve 49. 0 The inlet of the circulation pump 43 is connected to a flexible supply duct 50, provided with a valve 51 as well as a suction lance 52. This lance 52 can selectively be immersed in the coating liquid reservoir 36 (see FIG. 9) or in the spent cleaning liquid reservoir 53 ( see figure 5) or not to be immersed in any tank (see figures 4 and 6 to 8).

The inlet of the circulation pump 43 is also provided with two pipes 54 and 55, each provided with a valve 56 and 57, one being immersed in the spent cleaning liquid tank 53 and the other in a tank. with fresh cleaning fluid 58. In the reservoir 53, an outlet can be provided at 59 to a reservoir of cleaning liquid to be regenerated 60.

In the example illustrated, the valves, the circulation pump and the compressed air source can be put into operation according to an automated program. The opening and closing of the valves is controlled automatically and their positions are shown in the figures and will therefore not be the subject of a more precise description.

After a coating step, it may be necessary to clean the device. After spacing between the support cylinder 1 and the other cylinders in a known manner, the operator begins by purging the coating liquid supply circuit, as illustrated in FIG. 4. Air is drawn into the suction lance 52, previously taken out of the reservoir 36. It passes through the conduit 50, the circulation pump 43 and the supply conduit 30. It thus purges this supply circuit of coating liquid and the purged liquid is recovered in the lower shell 33, then recycled in the tank 36.

As shown in FIG. 5, the operator immerses the suction lance 52 as well as the discharge conduit 34 in the spent cleaning liquid tank 53. It is therefore the same circuit which served for the supply of liquid coating which serves to purge this circuit and to introduce the cleaning liquid.

The upper shell 37 and the lower shell 33 are now in the closed position, and, for example for 10 seconds, the cleaning liquid will wash the coating liquid supply circuit.

As illustrated in FIG. 6, the suction lance 52 is again removed from the reservoir 53. Through the hose 55, cleaning liquid is sprayed for approximately 2 minutes into the interior of the enclosure formed by the shells, via the nozzles 39. The liquid thus washes the entire device and the used cleaning liquid returns to reservoir 53.

During a possible subsequent sequence of for example 15 seconds, illustrated in FIG. 7, the valve 57 is closed and the valve 56 is opened, which makes it possible to suck in fresh cleaning liquid from the tank 58 and thus rinse installation.

In the possible subsequent sequence shown in FIG. 8 and which may last approximately 2 minutes, all the inputs and outputs of the circulation pump 43 are closed. Compressed air is then injected through the same nozzles 39, inside the enclosure, to purge the installation and dry it. It is possible to provide, connected to the release duct 38, a suction system, not shown.

After drying, the shells 33 and 37 are separated from one another as shown in FIG. 9, the suction lance 52 is again immersed in the coating liquid reservoir 36 as well as the discharge conduit 34 and the supply circuit is again open. The device is then ready for a new application command.

The total time for such a cleaning can be approximately 10 minutes and the total consumption of cleaning liquid by 20 liters, whereas currently one can envisage a triple of time and a doubled quantity of product. Manual operations, often dangerous and unhealthy, such as cleaning the sides of the cylinders should no longer be considered. It should be understood that the present invention is in no way limited to the embodiments described above and that many modifications can be made thereto without departing from the scope of the appended claims.

Claims

1. Device for applying coating liquid to a sheet, comprising a rotary support cylinder (1) around which a sheet (2) runs continuously, means for supplying coating liquid, a collecting cylinder ( 3) liquid film, rotating, supplied by the supply means, and optionally means for transferring the liquid film from the collecting cylinder (3) to the sheet metal (2) running around the support cylinder

(D, characterized in that it further comprises a washing device comprising

- a lower shell (33) forming a recovery container and an upper shell (34) mutually movable between a closed position in which they form a closed enclosure containing the supply means, the collecting cylinder (3) and the means of transfer and an open position in which they are spaced from each other, 0 - a cleaning liquid reserve container (53), a coating liquid reserve container (36), a source of compressed air (47), first circulation means which are capable of supplying the supply means, in the open position of the enclosure, with coating liquid from the coating liquid reserve container (36), second means circulation which are capable of supplying the supply means, in the closed position of the enclosure, with cleaning liquid from the reserve container of cleaning liquid (0), projection means (39) which are capable of projecting cleaning liquid through at least one of the two shells for washing the elements enclosed by the enclosure in the closed position, and - optionally means for injecting compressed gas (39 ) through at least one of the two shells to dry the elements enclosed by the enclosure in the closed position.

2. Device according to claim 1, characterized in that the washing device comprises, as first and second circulation means, a circulation pump (43) and a circuit comprising a supply duct (30) for introducing either coating liquid, either cleaning liquid in the supply means (4) and an outlet conduit (34) for discharging either coating liquid or cleaning liquid, from the recovery container (33).

3. Device according to either of Claims 1 and

2, characterized in that the liquid spraying means serve simultaneously as gas injection means.

4. Device according to claim 3, characterized in that the projection means serving simultaneously as injection means are connected to the aforementioned circulation pump (43) for circulating cleaning liquid and to a source of compressed air ( 47) to inject compressed air.

5. Device according to any one of claims 1 to 4, characterized in that the washing apparatus further comprises purge means which are capable of passing a purge gas through the supply means.

6. Device according to claim 5, characterized in that the purge means supply the circulation pump and said circuit with said purge gas.

7. Device according to any one of claims 1 to 6, characterized in that, in the washing device, the lower shell (33) is arranged so that it can be connected alternately to the container for reserving coating liquid ( 36) and to the cleaning liquid reserve container (53), so as to allow recycling thereof.

8. Device according to any one of claims 1 to 7, characterized in that the supply means comprise a supply container (4) containing said liquid and having a liquid outlet opening (8) extending along the collecting cylinder (3), in a lower part of said container (4), and a flexible doctor blade (9) arranged on the supply container (4) so as to limit the outlet opening (8), towards the down, and to be pressed against the collecting cylinder (3) to apply the film of liquid.

9. Device according to any one of claims 1 to 7, characterized in that the supply means comprise an inkwell in which partially bathes the collecting cylinder.

10. Device according to any one of claims 1 to 9, characterized in that the collecting cylinder (3) has a peripheral surface applied to the sheet (2) running around the support cylinder

⁽ D-

11. Device according to any one of claims 1 to 9, characterized in that it comprises, as transfer means, at least one rotary cylinder (31, 32) between the collecting cylinder (3) and the sheet (2) which scrolls around the support cylinder (1).

12. Device according to one of claims 10 and 11, characterized in that the supply means comprise an additional rotary cylinder pressed against the collecting cylinder forming between them an air gap in which the supplied coating liquid is received.