ES2307686T3 - COATING INSTALLATION WITH A REGULATION CIRCUIT. - Google Patents

Abstract

The system for serial application of paint or lacquer or other coating to workpieces has a control loop for regulating the pressure and/or flow rate of the color flowing through a conduit (9). A control member (2) for a parameter to be regulated is connected in the conduit. The control member is formed by a pneumatically or electrically driven valve (20) in the form of a cut-off valve. The drive unit (13) is controlled in dependence on the actual measured value of the parameter of the coating to be regulated.

Description

Coating installation with a circuit regulation.

The invention relates to a coating installation with a regulation circuit for the regulation of the pressure and / or the flow of colored paint flowing through a conduit according to the preamble of the claim.
tion 1.

Especially it is an installation of coating for serial painting work pieces, as per example bodies of motor vehicles, with colors that They change frequently. In installations of this type acts usually as a color change element an arrangement formed by pneumatically controlled color valves assigned in each case to a color that can be selected, whose output is connected, through a color pressure regulator and a pump dosing, to a sprayer (DÜRR, Technisches Handbuch, Einführung in die Technik der PKW-Lackierung, April from 1999). Color valves of the known color changer they have two switching positions in which they close or they open the way to the common color channel (this is about both of 2/2 way valves). A desired color is selected by loading the corresponding color valve with air of control by means of previously connected magnetic valves, the which transform electrical signals from the control of the installation in pneumatic signals. Since each color is assigned a magnetic valve, there is a number correspondingly large magnetic valves and, in the known facilities, you have to drive an equal number of large of control lines through the painting machine. Too it is possible to mount magnetic valves directly to the valve color (DE-A-10056259, published on 23.05.2002), being able to use magnetic valves that commute directly or indirectly.

The color pressure regulator, arranged usually at the output of the color changer, you can take care of a prior pressure regulation of the dosing pump, but it can also serve as an adjustment component for regulation of amount of color. A desired color paint pressure (or in the case of another liquid) it is adjusted in the regulators of color pressure known pneumatically by the pressure of the control air, which is isolated from the liquid by two or three membranes The control air pressure is regulated, in the closed regulation circuit, by an electronic device of control, which compares the actual value of the pressure of a valve of proportional pressure regulation generated by the control air with a theoretical value of the pressure and that controls the valve pressure regulation with a corresponding amount of adjustment. Therefore, here the color pressure is not directly regulated but the control air pressure, which is passed by the regulator from color pressure to paint pressure with a ratio of transformation (for example 2: 1) determined by the ratio of membrane surfaces. Color pressure regulators of the known systems serve as pressure multipliers, since the necessary color pressure may be greater than the air pressure available in the regulation system. It is also possible to supply the electronic regulation device with values actual pressure measured at the inputs and / or outputs of a dosing pump, on which the magnitude of adjustment for proportional valve.

Known color pressure regulators (DÜRR, Technische Beschreibung für Farbdruckregler für
EcoMCC3, 13.03.2001), because of the membranes with a relatively large surface area necessary, large dead spaces, which during each color change give rise to large losses of color and washing agent. In addition they result, not only because of an unfavorable path of the liquid path in the color pressure regulator, not only color deposits, but also color losses, which have a major impact on washing and during the delivery of new color, given that for a small pressure a greater demand of washing agent for subsequent components is necessary, while during the impulsion of the new color the impulse time is prolonged. The time of color change prolonged by the washing and the drive reduces the productivity of the coating installation. In addition, the membranes of the color pressure regulator are frequently damaged due to the high load, thereby suffering the reliability of the process. Especially during the Reflow reflux technique, in which the color paint is pushed back by a scraper in the direction opposite to that of circulation through the color pressure regulator, the membranes are loaded by the high pressures necessary to it. In addition, the membranes allow only limited dynamics and dosing precision as a "soft" member of the control circuit.

From EP 0 075 258 A it is known a color pressure regulator for an installation of coating in the form of a needle valve with actuation of membrane, which acts as an adjustment element in a circuit regulation, in which the amount of liquid from a volumetric measuring cell.

Document DE 38 22 835 A describes the regulation of the amount of color of a robot to paint, in which,  In the closed regulation circuit, the amount of color is measured by a flow measurement cell and a regulator, depending on this real value and theoretical values of the control of Stored programming keeps paint flow constant with an adjustment valve, electrically or pneumatically operated, which It contains a rotating piston. For color pressure adjustment is arranged, between the flow measurement cell and a color changer, a pneumatic color pressure regulator separated.

From US 4 720 801 another known color quantity regulation circuit with a cell flow measurement and a control valve, driven by a motor step by step

From EP 0 480 080 A it is known how to adjust the flow rate in a coating device with a flow control valve in the form of a valve needle, which is controlled by its electromagnetically by pulse signals with pulse duration or period of variable momentum Flow control valves of this type they can form the color entries of a color changer of the coating device For oscillation compensation from the pressure of the coating material its pressure is measured before and after the flow control valve and the pulse duration or the impulse period in correspondence with The measured pressure.

From EP 1 237 061 A (published 04.09.2002) a controlled valve arrangement is known pneumatically in which control signals are assigned numerically to individual valves and their assignment is transmitted in binary coded form, because, depending on the ordinal number of an actuated valve, it Simultaneously transmit two or more control signals. At valves is assigned a decoding device, which decode the binary coded control signals and the supplies the controlled valve.

The invention poses the problem of provide a cladding installation with an element of Reliable adjustment for color paint pressure, which has a smaller dead space volume and that can be washed quickly and With small loss of color and washing agent.

This problem is solved by characteristics of the claims.

In addition to the advantage of space volume noticeably lower dead, compared to pressure regulators  conventional color, adjustment element and minor material losses, installation color paths described here can be washed more quickly and effectively than until now. In addition, the valves to be used according to the invention are more reliable in constructive closure than the membrane color pressure regulators hitherto usual. In use of the shut-off valve as an adjustment element for the regulation of color quantity it is achieved, among others things, a greater dynamic. It also increases, through minors loss of color change and a better possibility of washing, the profitability of color quantity regulation which, between other things, it is important while using varnishes water with inductive measuring cells.

When the regulation circuit is it supplies as a real value the signal of a pressure sensor, which  measures the color pressure in the connected conduit after adjustment element, can be monitored without much complication in a constantly changing the pressure color system that reigns in your inside.

When the adjustment element is activated electrically, that is for example by means of a linear servomotor or by a proportional magnet, this has the advantage, in addition to that the pressurized air connections would be suppressed otherwise necessary, of a regulation dynamic especially high.

Especially advantageous is, according to a improvement of the invention, the combination with a arrangement of color change valves, to which they are connected, in the manner known per se, through in each case a controlled color valve, several pipes for each case other colors that can be selected from the color paint that must be supplied to the cladding body. In this refinement each of the color valves is formed by an adjustment element for the regulation of the pressure and the amount of color paint, which is formed in each case, with constructive form of shut-off valve, by a valve actuated pneumatically or electrically, whose drive device is controlled depending on the actual value of the magnitude of paint of color to regulate. Since here the function of the regulator  color pressure hitherto usual take over valves of color, you can do without one of the color changers connected after the color pressure regulator. Thanks to that its disadvantages such as the complexity of components, washing complexity as well as losses of color, washing agent and due to washing time.

The invention is explained in greater detail to from the embodiments shown in the drawing. In the drawing, the figures represent in:

Figure 1, a schematic representation of a part of a siding installation with a regulator color pressure;

Figure 2, a driven adjustment element pneumatically suitable for the invention;

Figure 3, the representation corresponding to Figure 1 of a siding installation in structuring for the regulation of the amount of color;

Figure 4, an adjustment element with electric drive, suitable for the invention,

Figure 5, another embodiment of a electrically operated adjustment element;

Figure 6, the schematic representation of a part of a siding installation with an arrangement of color change valves formed according to the invention;

Figure 7, a connection scheme for the color valve control of the color changer of the figure 6,

Figure 8, a constructive form, corresponding to the connection scheme of figure 7, of a module of control for the control of the color valves of figure 6 in their different possible switching positions; Y

Figure 9, a modified constructive form of the module of figure 6, represents in a simplified way for Only four exits.

According to figure 1 it is connected, between the output conduction 9 of a conventional color changer (no represented) and an equally conventional sprayer 1, a 2 color pressure regulator as adjustment element for the color paint pressure adjustment to be supplied to sprayer 1. The color pressure regulator 2 is controlled by the air pressure (P) at the outlet of a regulating valve pressure 3 formed as a pneumatic proportional valve, which is connected to the inlet to a source of pressurized air 4 and that receives from an electronic regulation device 5, through a conduit 6, for example a magnitude of adjustment (E) electric. The electronic regulating device exchanges with the control of the higher range SPS installation or with another control, information on real and theoretical values as well as parameters of operation.

As stated above, the part of Installation represented corresponds to the state of the art. In the usual comparable systems until now were usually regulated the outlet pressure of the pressure regulating valve 3 in the closed circuit, that is the electronic device of regulation 5 compared, for the generation of the magnitude of setting, the theoretical value of the preset pressure with the value actual pressure supplied to it by the outlet of the valve pressure regulation 3. Instead, it was already possible to use as actual value the pressure measured at the inlet or outlet of a gear wheel dosing pump connected between the regulator color pressure 2 and sprayer 1.

In the regulation circuit described in the Present memory for color pressure regulation is measured the color pressure, which is used as the actual value, preferably directly to the output of the color pressure regulator 2 and it supplies from there, through conduction 7, to the device electronic regulation 5.

The regulation circuit according to figure 1 described herein differs especially from those known facilities mentioned at the beginning because the regulator Color pressure does not only work as a multiplier of pressure but is controlled with direct pressure dependence Of paint. The color pressure regulator 2 can present the construction of a shut-off valve, known to others purposes, whose opening width can be controlled by a pneumatic drive (or in other embodiments) electric). In the case of a needle operated valve pneumatically by means of a plunger (or possibly also by a membrane) is the advantage that the force exerted by the color pressure on the needle, because of the small surface of the needle, is always much smaller than the regulating force available, acting on the plunger (or membrane). With it the Regulation is much more dynamic than until now.

A suitable construction for the regulator of color pressure 2 is represented in figure 2. Here it is of a needle valve 20 known per se with valve seat positive, whose valve needle 12 supported movable in the body valve 11 is displaced and adjusted by a piston 13 that can be load pneumatically against the force of a spring 14. The valve needle 12 and plunger 13 are represented in two positions different; in the first position the conical valve tip 15 is pressed by the spring 14 in the valve seat 16, so that the valve closes the path from entry 17 to exit 18. In the second position, represented in 15 'and 13', the valve is more or less open, by the control air pressure acting on the space 19 on the plunger 13 ', depending on its size. The space 19 is connected, in the example contemplated, to the output of the pressure regulating valve 3 of figure 1, while the input 17 is connected to the color changer and output 18 it is with sprayer 1.

Figure 3 shows the use of the circuit of regulation described here for the regulation of the amount of color. Sprayer 1, with the main needle valve HNV usual schematically represented, the pressure regulator of color 2, pressure regulating valve 3, air source at pressure 4 and the control of the SPS installation coincide with the corresponding elements of figure 1, and can then be the adjustment element that then acts as a pressure regulator of color 2 also, for example, a needle valve according to the figure 2. Since then, unlike the regulation circuit of color pressure according to figure 1, however, the color flow to be supplied to sprayer 1, it will be supplies the electronic regulating device 5 ', through a conduit 30, the actual value of the volumetric flow of the colored paint flowing to sprayer 1, which is measured by one of the connected color quantity sensors 31 after color pressure regulator 2. In case of divergences of this real value with respect to the theoretical value compared with it, the electronic control device 5 'controls the pressure regulating valve 3 with the magnitude of adjustment corresponding through conduction 6, so that the pressure regulating valve 3 opens more or less, to the extent necessary, the valve that forms the color pressure regulator 2.

Since during the regulation of the amount of color is strangled the volumetric flow of color, it could dispense here with the pressure measurement through the conduction according to figure 1. Pressure measurement at the outlet of the color pressure regulator 2 and the transmission of the value of the pressure through conduction 7 may make sense however for surveillance purposes, etc.

As mentioned above adjustment that forms the color pressure regulator can be also an electrically operated shut-off valve. An example of this is the needle valve 40 with negative valve seat, shown in Figure 4, and a drive motor 41 electric for valve needle 42 for width adjustment opening. The valve needle is represented, as in the Figure 2, also again in both the closing position and also in the opening position that can be recognized in 42 '. The drive motor 41 may be made for example as linear servomotor, that is as direct linear drive, or as indirect drive, for example with a thread piece of balls or also, in the way itself known by hydraulics, as proportional magnet.

The pressure sensor provided for example in Figures 1 and 3 for the generation of signals of real pressure value is preferably mounted directly on the adjusting element used in each case, therefore here to the needle valve 40, or it is mounted, like the pressure sensor 43 shown, on the valve, so that the color pressure can be measured directly on the valve seat. The signal generated in the electrical output line 44 of the
Pressure sensor 43 would be transmitted, in Figures 1 and 3, as the actual value of the pressure through conduit 7.

A needle valve 50 actuated in a manner electromagnetically suitable, which can be used as adjustment element of the regulation circuit described here instead of the pneumatically controlled color pressure regulator 2 of the figure 1 or figure 3, is schematically represented in the Figure 5. The valve needle 52 of this valve is pushed by a spring 54 in the closed position against the valve seat 55 and is stretched by a proportional magnet coupled with the stem of needle, whose winding 53 acts on the armature 51 of the needle of valve, in a manner known per se, against the force of spring 54 in the opening position, in which the path from the entrance of color 57 at the exit of color 58 is more or less open depending of the electric current flowing through the winding magnetic.

In an actuated adjustment element electrically from the regulation circuit were supplied, instead of the pressure regulating valve of figure 1 and figure 3, electrical adjustment signals by the device electronic control to drive the element of adjustment.

The combination is shown in figure 6 especially advantageous of the regulation circuit described here with the color valves F1, F2, F3, etc., of a color changer 60 assigned in each case to a color that can be selected and to in each case a color line L1, L2, L3, etc., whose output leads to sprayer Z, for example, through a pump dosage 62 driven by an M motor. According to a improvement of the invention, each of the color valves It is no longer formed as up to now as 2/2 way valves simple to open and close the corresponding color path, but as an adjustment element for pressure regulation or amount of color paint, whose drive device is controlled depending on the actual value of the magnitude of the paint of color to be regulated. They serve then therefore the own color valves F1, F2, F3, etc. of the color changer 60 as adjustment elements for the magnitude to be regulated. When the color pressure must be regulated, it can be supplied to the electronic regulation device as real value for example the color pressure measured at the inlet (or outlet) of the pump of dosage 62.

60 color changer color valves they can be electrically or pneumatically operated and controlled by means of electrical or pneumatic adjustment signals. Suppose, for example, that similar to what happens for the circuits of regulation according to figure 1 and figure 3, which are actuated by the air pressure, generated by a proportional valve, to the input 63 of a control module 64 to be described at then it has outputs 65 connected each with one of the color valves and that delivers this outlet air pressure of the pressure regulating valve common to all valves color in its controlled output in each case. The control module 64 It therefore acts as a travel control device for apply the pressurized air, which as a pneumatic adjustment magnitude, to the desired color valve in each case. All remaining color valves are held by a spring in its position of closure, since in each case only one valve can be opened color. To select output 65, in which it must be delivered the magnitude of pneumatic adjustment, the control module 64 is controlled by pneumatic or electrical control signals binary inputs B, C and D. This system avoids the need for a proper proportional regulation valve for each of the, In certain cases, many F1, F2, F3 color valves, etc.

The proportional valve could be mounted also between the external pressure air supply and the inlet of pressurized air from a so-called island of valves, usual in the trade, which contains color valves constructively block

A suitable possibility for the realization of control module 64 of figure 6 is a valve block distributors gathered in several planes which, to save control lines, are controlled, in a way in itself known, using binary coded input signals. The schematic connection plane of a control device paths for n = 3 input signals or planes and therefore  2 n = 8 outputs, that is eight colors that can be select, is represented in figure 7, being designated By means of the air pressure to be supplied in each case to one of the eight outputs and through B, C and D, as in figure 6, Binary input signals. The input signals B, C and D they can be pneumatic signals generated for example by valves magnetic, with two possible pressure values (connected / disconnected), and that can be assigned to the valves F1, F2, F3, etc. connected to the outputs according to the table next, that is, they can be decoded by the module control 64:

one

More generally they can be decoded to from n input signals 2 n output signals. In the many more than only 2 3 = 8 can be selected colors and therefore more than three planes are necessary represented in figure 7 with a 3/2, 6/2 or 12/2 way. The arrangement according to figure 7 can be extended discretionally up to 16, 32, etc. outputs by mounting 24/2 and 48/2 way valves, etc., generally needed for k = 1, 2, 3 ... flat in each case 2k valves, +2 ^ (k-1) / 2-way, to activate with n signals of Binary input 2 n outputs. It is also possible to replace some of the distributor valves that are needed by valves partials combined discretionally that is, for example, perform the 48/2 way valve, necessary as a fifth plane, through two 24/2 way valves arranged next to each other, to which is connected in each case one half of the outputs of the 24/2 way valve previously connected from the fourth plane.

In figure 8 it is represented, in correspondence with the simplified example of figure 7, schematically a preferred embodiment, because It is especially compact and therefore saves space and also requires reduced assembly and installation complexity of the module control 64 (figure 6) for eight color valves. Peculiarity it is then the formation of the 3/2, 6/2 and 12/2 way valves that they form the three planes in a block type housing with paths for the inlet air pressure A of the regulating valve common pressure distributed as a maze. Three valves are therefore connected to each other in their housing block common by drills. Figure 8 shows the control module in  its eight different possible positions depending on the signals B, C and D binary input corresponding to the table higher. These positions are given in the example considered through the air pressures that exist or are missing, that form these input signals, which according to the representation act on in each case a plunger against the force of in each case a recoil spring.

A constructive way, which in principle corresponds to figure 8, similarly advantageous, but which should eventually be preferred in cases of application of the module control with circular control movements of the arrangement of piston, is schematically represented in figure 9, an embodiment being selected for simplicity with only two planes for four output signals. Both piston arrangements 90, 91 are rotatably supported concentrically in a housing block 92 and are loaded, in the considered example, in control inputs 93, 94 for both pressure signals B or C, so that the regulation pressure for color valves applied to input 95 arrives, depending on the switching position, through the housing openings 96 connecting the two valve systems, to one of the four outputs 98. The housing block 92 may be made in two parts, being able to be arranged in one of the parts the exits and in the other part the entrances 93 and 94.

The control module described in its form of embodiment according to figure 8 and figure 9 is not suitable only for the regulation of color valves of a changer colored, for example according to figure 6, but it is so more general for the control of a large number of valves as per example the control valves on / off conventional color changers or other valves, in the which were so far undesirably disadvantageous the many control conduits, the great need for space and / or a great complexity of components and installation.

On the other hand the color valves F1, F2, F3, etc., which act as adjustment adjustment elements of the Color changer 60 of Figure 6, can also be controlled electrically, instead of through valve arrangements pneumatic distributors according to figure 8 and figure 9, and can be adjusted to the corresponding theoretical value. To this end they can contain in each case an appropriate electronic circuit that supply an electric valve drive, for example according to figure 4 or figure 5, a setting value common to one or where appropriate to all valves, when the valve in question is selected by separate control signals. The signs of control can be supplied, in a known way, through a data bus system. You can then also use a pneumatic / electronic bus control system as it is known, for example, from document DE 10056259.

Claims (15)

1. Coating installation for the serial coating of workpieces with a circuit regulation for color paint pressure regulation flowing through a conduit (9, 61), with an adjustment element connected to the conduction (9, 61) for the pressure to be regulated, which is formed by a valve (20, 40, 50), with constructive form of shut-off valve, pneumatically or electrically operated, whose drive device is controlled depending on actual measured value of the paint pressure of color to be adjusted, containing the drive device a Pneumatically actuated piston (13) or drive motor (41) electric or a proportional magnet, to adjust the width of valve opening (20, 40, 50) depending on the magnitude of control. 2. Installation according to claim 1, characterized in that the adjustment element is a needle valve (20, 40, 50). 3. Installation according to claim 1 or 2, characterized in that the actuator contains a pneumatic actuator with air pressure controlled by a proportional valve. 4. Installation according to one of the preceding claims, characterized in that the adjustment element contains a spring (14) that closes the valve in the idle state. 5. Installation according to one of the preceding claims, characterized in that the signal of a pressure sensor (43) is supplied as a real value to the control circuit, and which measures the color pressure in the conduit connected downstream of the adjustment element . 6. Installation according to one of the preceding claims, characterized in that the adjustment element has a pressure sensor (43) mounted on the adjustment element or forming part thereof. 7. Installation according to one of the preceding claims, characterized in that the actual value of the regulation circuit measures the pressure on the outlet side of the valve seat of a needle valve (40). 8. Installation according to one of the preceding claims, characterized in that a metering device for color painting is connected upstream or preferably downstream of the adjustment element. 9. Installation according to one of the preceding claims, characterized in that the adjustment element is connected downstream of an arrangement of color change valves. 10. Installation according to one of the preceding claims with an arrangement of color change valves, to which they are connected in each case, through a controlled color valve (F1, F2, F3), several conduits for in each case other colors that can be selected from the color paint that must be supplied to the coating member (Z), characterized in that each of the color valves (F1, F2, F3) is formed by an adjustment element for the regulation of the pressure or the amount of the colored paint, which is formed in each case by a valve, with a constructive form of a shut-off valve, pneumatically or electrically operated, whose actuating device is controlled depending on the actual measured value of the magnitude It should be regulated from the color paint. 11. Installation according to claim 10, characterized in that upstream of the pneumatically operated color valves (F1, F2, F3) is connected a proportional valve common to them, whose pneumatic output signal can be supplied, through a unit of route control, to the color valve that must be controlled in each case. 12. Installation according to claim 11, characterized in that the travel control unit contains a number n of 2 k + 2 (k-1) / 2-way valves with k = 1, 2, 3. .., formed in a common housing block, connected to each other by means of openings inside the housing block, the distribution valve for k = 1 being connected with its input to the proportional valve and with its two outputs to the two valve inlets distributor for k = 2 and its four outputs to the four inputs of the distributor valve for k = 3, etc. where appropriate, k> 3, and each distribution valve being switchable between its two positions for each case one of the n control signals for the control of the 2 n outputs of the route control unit connected to the color valves (F1, F2, F3). 13. Installation according to one of the preceding claims, with an arrangement of color change valves to which a controlled color valve (F1, F2, etc.) is connected, in each case, several color lines ( L1, L2, etc.) in each case other colors that can be selected from the color paint that must be supplied to the coating organ, characterized in that upstream of the color valves (F1, F2, etc.) is connected a valve that is common to them, whose pneumatic output signal can be supplied to the valve that must be controlled in each case through a travel control unit, which contains a number of valves of 2 k + 2 ^ (k-1) / 2-way with k = 1, 2, 3 ... formed in a common housing block, connected to each other through openings inside the housing block, the distribution valve for k = 1 being connected with its input to the proportional valve and with its two outputs to the s two inputs of the distributor valve for k = 2 and its four outputs to the four inputs of the distributor valve for k = 3, etc. if necessary k> 3, and each distribution valve can be switched between its two positions in each case one of the n control signals for the control of the 2 n outputs (65) of the travel control unit connected to the color valves (F1, F2, etc.). 14. Installation according to claim 12 or 13, characterized in that for switching the distribution valves within the housing block, disposable piston arrangements are provided, with which the openings leading to the outlets (65) can be closed or opened. through the housing block. 15. Installation according to claim 10, characterized in that a proportional valve is mounted on the pressurized air inlet of a block-type valve island containing the color valves.