EP0842706B1 - Coating installation and method for controlling the flow of coating material in this installation - Google Patents

Description

The invention relates to a method for automatic control the material flow in a coating system Series coating of workpieces and a corresponding one Coating line according to the generic term of the independent Claims.

A typical application example for this is the automatic one Paint supply for painting systems for serial coating of Workpieces such as Motor vehicle bodies, which as Loop color circulation systems are designed to be as possible largely the deposition of the paint during coating breaks to avoid. The well-known cabin ring line systems consist of a feed line from each color Paint container and the feed pump in the paint mixing room Paint booth and a return line from the paint booth via an adjustable return control valve back to Paint container. With the pressure difference between the outlet the feed pump and the adjustable return control valve a continuous color circulation is created. In the Paint booths are usually multiple atomizers or other coating devices distributed for the several Ink acceptance or connection points (so-called ink niches) different locations along the cabin are provided. The automatic coating machines such as. so-called side machines are close to or in the Cabin wall arranged, and more can be inside the cabin Machines such as the so-called roof machines provided his. In newer plants of this type are the Changing the paint colors required valve arrangements (Color changer) for example in the machine arm or in "Roof beams" of the roof machine and therefore in the immediate vicinity the atomizer because, among other things, because of Disposal problems of undesired loss of paint and solvent be reduced to a minimum when changing colors.

According to the preamble of independent claim 3, a known way of connecting the ring line with the coating devices, as shown in FIG. 1A, each a simple one Branch line at the connection points, which, however, the Disadvantage has that the coating material in longer Can lay coating breaks in the stub and / or be withdrawn from the branch line before production begins got to.

Instead, it is also possible to use one of the paint containers outgoing, decreasing in diameter in the direction of flow Supply line to supply points. This Flow line ends at the last ink acceptance or Junction points (color niche). The return line starts the second ink take-off point and has one in the flow direction increasing diameter. The color circulation between pre and The return line is via the ink sampling point. By this is a circulation between the paint container and the Tapping points possible. This may cause the withdrawal problem can be avoided, but this system is complex because for the Return line a second, like the main line around the entire pipeline piping around is required. Furthermore, is to supply all tapping points and due considerable pressure losses a high material flow rate required, in addition to energy expenditure, Pump wear etc. also high shear loads of the Paint material result.

According to the preamble of independent claim 1, is from US-A-4 830 055 between the supply system a coating system and one or more spray devices switched, from the usual valve modules for the known different colors of existing color changers, between the respective paint supply lines and associated return lines each have a bypass path contains a bypass valve. If that's from the supply line upcoming coating material of a given color is not required it circulates after one of the spray devices is closed upstream valve through the bypass and concerned return line back to the supply system.

The invention has for its object a method and to specify a coating system that stops the Coating material easier and with less construction and Avoid energy expenditure than before.

This object is achieved through the features of the claims solved.

Fig. 1A und 1B

zwei nicht der Erfindung entsprechende Systeme;

Fig. 2

eine schematische Darstellung zur Erläuterung des Prinzips der Erfindung; und

Fig. 3

eine schematische Darstellung einer typischen Ausführungsform einer erfindungsgemäßen Beschichtungsanlage.

The invention creates a simple one-pipe circulation system, the separate return of which ensures the desired continuous circulation of the coating material up to the valve arrangements (color changer) of the coating device, causes low pressure losses and does not require high delivery rates.
The invention is explained in more detail with reference to the drawing. Show it:

1A and 1B

two systems not in accordance with the invention;

Fig. 2

a schematic representation to explain the principle of the invention; and

Fig. 3

is a schematic representation of a typical embodiment of a coating system according to the invention.

1A shows a known ink supply system with a Ring line 1, coming from a supply system 2 and circulating coating material flowing back there. The supply system can e.g. in a color mixing room are located. A branch line 3 branches off from the ring line 1, via a control valve to the coating device 4 leads.

1B shows the alternative possibility mentioned above with a main line 6 coming from the supply system 2, from the branches a feed line 7, which over the illustrated Valve arrangement on the one hand with the coating device 4 and on the other hand with one back into the supply system 2 leading return line 8 is connectable. Over in the Main line 6 and the return line 8 switched pre-pressure or. Return regulator can provide the required operating pressure can be set.

The principle of the invention results from Fig. 2. Here is (per Color) a single complete ring line 10 is present, which is fed by a supply system 2 as before, and from the at the connection point 11 a feed line 12 to the Valve arrangement 13 of the coating device 14 leads. According to the invention, the feed line 12 is here for example via a valve of the arrangement 13 with a separate return line 15 connected to or downstream behind a shut-off point of the ring line 10 in this ends. The shut-off point is a downstream of the Junction 11 switched into the ring line automatically controlled shut-off valve 16 is formed.

During operation, i.e. when working The coating device 14, the shut-off valve 16 is open, so that the coating material continuously through the Ring line 10 from and back to the supply system 2 circulates and the part of the material required for spraying due to the working pressure in the ring line through the valve arrangement 13 to the coating device 14 flows.

In the coating breaks, however, the ring line on the Blocking point blocked by valve 16. At the same time when the coating device 14 is blocked, the path from the Feed line 12 to the return line 15 and from this in the unlocked part of the ring line 10 behind the Valve 16 released so that the coating material constantly through the feed line 12 and now also through the Return line 15 flows and can not settle. The Valve 16 is actuated by a control signal.

3 shows a typical coating system for Series coating of motor vehicle bodies shown. she contains (per color) a ring line 20 in the form of a one Paint booth 21 pipeline routed to a (here supply system (not shown) is connected. The Paint booth contains in the example shown in the indicated by the arrow 23 conveying direction of the bodies Six in a row consisting of hand spray guns Coating devices 25, six electrostatically working Coating devices 26 (e.g. rotary atomizers), further coating devices 27 on a roof machine, three consisting of automatic air atomizers Devices 28 and two other manually operated Coating devices 29. As shown, the Coating devices other than devices 27 and one device 28, as usual, each on the two Cabin sides distributed. The automatic motion machines moving coating devices are directly on the Cabin wall arranged. The respective color changers are located in the immediate vicinity of the coating devices, for example in the machine arm of the motion machines or in "Roof bars" of the roof machine to prevent paint and solvent losses reduced to a minimum when changing colors.

Branch at the connection points shown in the drawing from the ring line 20 the individual to one or more of the Coating devices 25 to 29 leading Feed lines 32 and 32 'from, the Feed lines 32 upstream of a first one Blocking point of the ring line 20 in the form of an automatic controlled shut-off valve 36 and that to the rest on the other cabin side arranged coating devices leading feed lines 32 'downstream behind the Valve 36 and upstream of a second shutoff point also in the form of an automatically controlled Shutoff valve 37 are.

Each of the branches branched from the main circulation or ring line 20 Feed lines 32 is on the (not shown) Valve arrangement of the coating arrangement to which it leads, for example via an automatically controlled valve Valve arrangement connected to a line 34, which in a separate return line 35 common to all lines 34 leads, which in turn on the shutoff valve 36 downstream opens into the ring line 20 behind the shut-off point. As well are on the other side of the cabin the outgoing lines 32 ' Valves and lines 34 'to one of these lines 34' shared separate return line 35 'connected to the shut-off valve 37 downstream behind this shut-off point opens into the ring line 20.

As shown with the coating devices 26 and 28 can lead to several atomizers feed lines fed by a common feed line 32 or 32 ' and in parallel to that coming from these atomizers Lines 34 and 34 'via a common line be connected to the return line 35 or 35 '.

There is one for each color that can be selected for the coating Ring line and associated supply and return lines intended. The valve arrangements mentioned Coating devices can include the color changer or be connected to a color changer with which the relevant coating device selectively over their Supply and return lines with the ring line for the desired color can be connected.

The cross section of the return lines 35 and 35 'can be seen in Flow direction gradually increase to the Keep pressure losses in operation small, taking the stages e.g. correspond to the distances between the lines 34, 34 ' can, so that the cross section from inflow to inflow is larger becomes. The supply and return lines can be advantageous e.g. consist of relatively simple hoses that are easy are controllable and not in contrast to the ring line 20 lead the entire cabin around.

The check valves 36 and 37 can simultaneously and can be controlled in the same direction by a common control signal, however there are other control options. You can be designed as a switchable multi-way valve that in your one switching state releases the ring line 20 and in the other Switching status blocks the ring line and at the same time a way for the return line 35 directly connected to the valve or 35 'in the respective unlocked part of the Ring line opens.

During the coating operation with a given color is the relevant ring line 20 when open Shutoff valves 36 and 37 open all the time, so that Coating material unhindered by the ring line 20 from and can circulate to the supply system. At the same time flows the coating material through the feed lines 32 and 32 ' to those of the coating devices, each work. Here others, e.g. before or after required coating devices are out of operation. All return lines can be connected to the Valve arrangements of the coating devices and / or on the shut-off valves 36 and 37 be blocked.

In contrast, the two are in the coating breaks of the plant Shut-off valves 36 and 37 automatically into the ring line 20 blocking position switched. That from the supply system upcoming coating material continues to flow through the Feed lines 32. But now it is from the valve arrangements of the coating devices concerned via the Lines 34 passed into the return line 35 and flows behind the shut-off point on the shut-off valve 36 back into the Ring line 20. Then it arrives at the connection points the other side of the cabin into the feed lines 32 'there and from there into the second return line 35 'and finally behind the second shut-off point on the shut-off valve 37 in again the ring line 20 leading to the supply system.

There can also be more than two shut-off points in the ring line be provided. On the other hand, the shut-off valves of the Ring line not during the entire break times of the Coating closed and the paths of the return lines be open, e.g. not if the coating company is interrupted for a long time.

Claims (9)

1. A method of automatically controlling the flow of material in a coating installation for the serial coating of workpieces, in which the coating material circulates during coating operation through a ring main (10, 20), from which it is conveyed at one or more connection points through a respective feed line (12, 32, 32') to a coating device (14, 25', 29), characterised in that during at least a portion of the breaks in coating operation, the ring main (10, 20) is closed downstream of the connection point or connection points and the coating material is fed back out of the respective feed line (12, 32, 32') through a separate return line (15, 35, 35') into the ring main (10, 20) downstream of the closure point.
2. A method as claimed in claim 1, characterised in that during the breaks in coating operation the ring main (20) is closed at a second position (37) situated downstream of the closure point (36) and the coating material coming out of the separate return line (35) is conducted in feed lines (32) leading out of the ring main (20) between the two closure points (36, 37) to further coating devices and is fed back from there into the ring main (20) downstream of the second closure point (37).
3. Coating installation for the serial coating of workpieces including a ring main (10, 20) connected to a supply system (2) and at least two feed lines (12, 32, 32') leading from the ring main at a respective connection point to a coating device (14, 25, 29), characterised in that connected into the ring main (10, 20) at a position located downstream of the connection points there is an automatically controlled shutoff valve (16, 36, 37) for shutting off the ring main (10, 20) and that the feed lines (12, 32, 32') are connected to a separate return line (15, 35, 35'), which is common to them and leads into the ring main (10, 20) downstream of the shutoff point (16, 36, 37).
4. Coating installation as claimed in claim 3, characterised in that the ring main (20) includes at least two shutoff valves (36, 37), that at least two feed lines (32), which lead from the ring main (20) upstream of the first shutoff point to a respective one or more coating devices (25, 29) are connected to a return line (35), which is common to them and leads into the ring main (20) downstream of the first shutoff point (36) and that between the two shutoff points (36, 37) further feed lines (32'), which lead from the ring main (20) to respective coating devices, are connected to a second separate return line (35'), which is common to them and leads into the ring main (20) downstream of the second shutoff point (27).
5. Coating installation as claimed in claim 4, characterised in that the two shutoff valves (36, 37) may be controlled at the same time and in the same sense.
6. Coating installation as claimed in one of claims 3-5, characterised in that connected upstream of the coating devices (25-29) there are valve arrangements, with which the connection of the feed lines (32, 32') with the return lines (35, 35') may be controlled.
7. Coating installation as claimed in one of claims 3-6, characterised in that, for each paint colour which may be selected in the coating process, a respective ring main and associated feed and return lines are provided and that the valve arrangements of the coating devices are constructed as a part of a paint changer or are connected to a paint changer, with which the coating devices may be connected selectively to all the ring mains.
8. Coating installation as claimed in one of claims 3-7, characterised in that the cross-sectional area of the separate return line (35, 35') increases incrementally in the flow direction.
9. Coating installation as claimed in one of claims 3-8, characterised in that the shutoff valve (36, 37) is constructed in the form of a switchable multiway valve, which opens the ring main (20) in the circulation direction in one switch position whilst in its second switch position it closes the ring main and conducts the coating material out of the separate return line (35, 35') into the portion of the ring main (20) which is not closed.

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