EP0886546A1

EP0886546A1 - Method and device for coating objects requiring frequently changes of coating material

Info

Publication number: EP0886546A1
Application number: EP96942228A
Authority: EP
Inventors: Christian Aeberhard
Original assignee: Ingenieurbuero Inovac
Current assignee: Ingenieurbuero Inovac
Priority date: 1995-12-29
Filing date: 1996-12-23
Publication date: 1998-12-30
Also published as: WO1997024189A1

Abstract

The method described calls for the different coating materials to be taken from working containers and fed, with continuous mixing, to ring mains from where each is selectively fed to a hollow-needle valve in a paint applicator fitted with a spray device, the hollow-needle valve bringing the coating materials to the immediate vicinity of the spray device. Each coating material is always fed to the same associated valve (81). Every time the coating material is changed, the valve (81a) in the paint applicator (28) is withdrawn from the applicator by a handling device and replaced by another valve (81b) corresponding to the next coating material to be sprayed. Those valves which are not inserted in the applicator are kept stowed in a storage rack (165).

Description

Method and device for coating objects with frequently changing types of coating media.

The invention relates to a method for coating objects with frequently changing types of coating media according to the preamble of patent claim 1 and a device according to the preamble of patent claim 4.

In painting lines for automobile bodies, it is common for bodies to follow one another immediately, which are painted with top coats of different colors. In the case of painting systems for painting lines of this type, a number of paint ring lines corresponding to the number of different paint colors is provided, in each of which the paint is circulated and is returned to all paint taps to the paint container. Circulating the color is necessary to keep its consistency even.

Various color changing systems are used in the application technology industry.

Known devices have tried to bring the color changing systems and the necessary valve devices as close as possible to the atomizing device, and also to keep the connecting lines between the color changing system and atomizing devices as short as possible in order to reduce the loss of dye and flushing media.

A paint circulation device, known from German patent application DE 3 130 096, uses two switchover valve arrangements. These are, by relatively longer Supply lines separated, connected to the actual spraying device. This separation or long hoses result in a very high loss of paint and rinsing liquid when the feed lines and the spray device are rinsed.

In order to reduce such high losses, a device has been proposed which is known from German patent application DT 2 043 789 and which has only one hose line between paint changer and spray device. A plurality of paint feed lines are fed to the paint changer, the latter in the form of a drum valve device which can be connected as close as possible to the spray device. A similar device is known from US Pat. No. 2,257,004. Although in these two known devices the supply line between the paint changer and the spray device is kept relatively short, the losses of paint and rinsing liquid which occur during a color change are still high, since the entire spray device and its cavities are also cleaned must become. The latter device is not suitable for fully automatic operation, since the drum must be operated by hand.

A further disadvantage of these devices is the limitation of the number of colors (e.g. a maximum of 18) which can be installed in the drum-shaped valve devices for reasons of space.

From the German application DE 3 927 880 a system is known with in-line valves between ink circulation pumps and a plurality of spraying devices. With this system it was important that the color change valves could be placed as close as possible to the spraying device around the paint line for the flushing process to keep. Depending on the type of construction of the coating machine or robot used, the movement loops of the paint lines are longer than desired because of the necessary movement sequences of the spraying devices. This means that the loss of color and detergent is still too high. It is approximately 150 to 200 cc in a spray device of this known system for a color change. The loss times are still very high and lie at 15 to 25 seas. for a color change. When used in the automotive sector, where a large number of spraying devices are arranged in different positions in the body and very frequent color changes take place every few minutes, there are total price losses in the order of 8 to 10 million Swiss francs during a year, only for one spray line.

Another system is known from German patent specification DT 1 402 627, whose color changer consists in introducing paint feed lines from the paint containers directly into the spraying device via pumps and shut-off valves. The line routes will probably be shortened. The main disadvantage of this system, however, is the possibility of mixing the colors in the spraying device, since there are no valves in the latter or in the feed lines. The immediate vicinity of the outflow opening is probably rinsed and washed with rinsing liquid by the individual paint connections. In the process, however, color components can be removed from the lines, which mix with one another when the color changes and cause color damage on the surfaces to be treated. The security of an absolute separation of the colors is not given here and therefore this system is unsuitable for automatic operation. This plant too can no longer meet today's requirements in bodywork spraying systems with regard to the required number of colors, since the number of lines in the spraying device is limited for reasons of space.

In the German patent application DE 3 312 268, a paint circulation system is known which has a ring line for each individual color, to which a circulation line is assigned, which extends into the vicinity of the spray device. Each circulation line has a color valve there. This means that short supply lines between the paint valve and the spraying device can be implemented, but only in the case of a single paint. In the case of several colors, an additional circulation line and pump are necessary, which means that cleaning them again leads to increased losses as in the systems already mentioned.

Another device known from German patent application DE 4 329 101 is provided with a color change system, which admittedly permits a greater number of colors than the aforementioned devices. However, there is the major disadvantage that always two feed channels present in the blocking members have a common output and thus result in the mixing of two colors, since the channels are not rinsed. The structural design also does not permit installation in the immediate vicinity of the spray device. The disadvantages of the high losses of dye and detergent are also present here.

An atomizer device, known from German patent application DE 4 330 602, has a plurality of color channels which run parallel to the axis of an atomizer head and into the spray device in this way integrated that their end openings extend as nozzles into the area of the atomizer head. The paint valves assigned to the paint channels for interrupting the paint flow in the channels are outside the spray device. A disadvantage of this atomizing device is that the lack of valves in the area of the channel ends (nozzles) poses a risk of mixing colors, in particular if detergent is used to dissolve the paint or color residues present in the channel ends. The proposed solution by sucking paint back into the channel does not remedy this deficiency. Especially in the case of large color differences, for example black and white, even the smallest amounts of mixtures cause a color falsification on the sprayed surfaces, which leads to subsequent improvements or even rejects with cost consequences. Another disadvantage of this device is that the number of color channels that can be installed is very limited (maximum ten) and does not meet today's requirements for painting car bodies with 32 or more colors. Another disadvantage is that the colors do not circulate in the channels. As a result, hardening and segregation (in particular in the case of paints containing metal) can occur in infrequently used paints, which cause faults in the spray process.

The known methods and devices include complicated constructions which cause large losses of dyeing and rinsing media and which require more time to be used in the course of the spraying process. This is particularly disadvantageous in fully automated coating systems in the automotive industry. In addition, the environment is polluted with excessive emissions. O 97/24189 _{pcτ / CH96 / 00458}

The present invention is therefore based on the object of proposing a method for coating objects with frequently changing types of coating media which overcomes these disadvantages. Likewise, a device for carrying out the method is to be proposed.

This object is achieved by the features of the characterizing part of claims 1 and 4.

The effective color change is first carried out immediately before atomization in the paint applicator. Since a separate hollow needle valve is used for each color, which is exchanged in succession in one and the same paint application device, and each hollow needle valve contains the valve systems necessary for the color closure, cleaning is limited only to that between the hollow needle valve and the surfaces of the paint application device immediately surrounding it .

The device according to the invention has the advantage that the color volume in the lines to be washed away during a color change is reduced to an absolute minimum. The loss of paint quantity will therefore be less than 2 cm3 with each color change. This is approximately 80 to 100 times less than with conventional systems. A smaller volume of flushing medium is therefore also required, as a result of which the overall loss rates are significantly reduced. The smaller flush volume also significantly increases the flush quality, i.e. the risk of color spreading is reduced to a minimum. This then leads to better coating qualities.

In the inventive device are the valve systems comparable with known color change valves are integrated directly in the movable hollow needle valve.

Another advantage is the shorter time required. If the time in known devices is approx. Lδ to 25 seconds, the main part being used for rinsing and pressing on the new paint, it is still approx. 8 to 9 seconds in the method and device according to the invention the effort for the motion sequences, ie including the handling of the hollow needle valves to be changed, approx. 5 to 6 seconds

Another advantage is that no switching element and no color line section are contacted with a different color from the paint supply to the atomizer device.

The color cycle is guaranteed from the color ring line right up to the atomizer device. This prevents segregation of the color media as a result of stationary color streams.

The device according to the invention with a ring cassette magazine according to the features of claims 8 or 9 offers particular advantages. The hoses connected to the hollow needle valves are moved only slightly, thereby reducing wear on them.

All of these advantages are particularly evident when used in automated systems, for example in the automotive industry. The device according to the invention can, due to slight modification, be used on all types of paint applicators available on the market, such as electrostatic high-speed rotary atomizers, air atomizer guns, HLVP guns, airless and air mix guns. Furthermore, it is possible to use the device in a non-automated paint shop.

In the following, for example, designs of devices for carrying out the method according to the invention are shown and explained in more detail.

It shows partly in a schematic representation

Fig.l a hollow needle valve in longitudinal section;

2 shows a hollow needle valve according to FIG. 1 installed in a rotary atomizer;

3 shows a hollow needle valve according to FIG. 1 installed in an air atomizer;

4 shows a hollow needle valve handling device in the

Longitudinal section with revolver magazine;

5 a handling device according to FIG. 4 in

Floor plan shown;

6 shows a handling device according to FIG. 4 in side elevation; 7 shows a perspective view of an ink application device with a coated ink application device and revolver magazine;

8 shows a perspective view of an ink application device with a coated ink application device and flat cassette magazine;

9 shows a perspective view of an ink application device with a coated ink application device and a pivotable ring cassette magazine;

10 shows a staining and rinsing media scheme;

11 shows a cross section through a hollow needle valve along the line XI - XI in FIG.

12 shows a perspective view of an ink application device with a coated ink application device and a fixed ring cassette magazine.

The same reference numerals are used in the drawings for functional parts that are essentially the same.

1 shows a hollow needle valve 81, consisting of a hollow needle valve sleeve 1 with a front end 82, a central region 90 and a rear end 83. From the central region 90 to the front end 82, the hollow needle valve sleeve 1 has an approximately cylindrical outside - Sheath 93. The hollow needle valve sleeve 1 has a bore 85 which extends from the rear end 83 to approximately the front end 82, where a valve chamber 86 is formed, the diameter of which is larger than the bore 85. A further valve chamber 23 connects to the valve chamber 86 coaxially to an axis 11 δ with a larger diameter. A valve seat 20 is formed between the valve chambers 23 and 86. The valve chamber 23 is closed at the end 82 of the hollow needle valve sleeve 1 by a sleeve part 84. The latter has a coaxial valve cone system with an outer sealing cone 3 and an inner sealing cone 4 which projects into the valve chamber 23. The sleeve part 84 has an opening 24. This is connected on the one hand via obliquely arranged bores 87 to the valve chamber 23 and on the other hand via bores 88 to a hollow shaft chamber 25 (described below).

In the example shown, the sleeve part 84 is shown schematically firmly connected to the outer jacket 93, i.e. out of one piece. For manufacturing and assembly reasons, however, the sleeve part 84 and thus the sealing cones 3 and 4 can advantageously be made as separate pieces and connected to the outer jacket 93 by means not shown.

In the central region 90, the outer casing 93 is provided with two collecting grooves 14 and 15. The collecting groove 14 is connected to the bore 85 by bores 91. A spiral groove 13 extends from the bores 91 to the front end of the bore 85 therein. A groove-shaped spiral run 16 extends from the collecting groove 15 on the outer casing 93 to its end in the region of the sleeve part 84 or spiral runs can be provided. Grooves in the outer jacket 93 are provided on the one hand between the collecting grooves 14 and 15 and on the other outside the collecting groove 14, for receiving sealing rings 92 and 94. Another Groove, outside the area of the spiral groove 13, is provided in the bore 85 for receiving a sealing ring 95.

In the area of the rear end 83, the hollow needle valve sleeve 1 has a retaining groove 18 on the circumference, into which a tensioning device 17, which is only shown schematically with dash-dotted lines, can engage.

The bore 85 has an internal thread 96 in the area of the rear end 83 for receiving a threaded spindle 5. The latter is part of a paint tube 2, which further consists of a cylindrical extension 98, a tubular part 97 and a valve head 99. The color tube 2 or the parts 98, 5, 97 and 99 are shown schematically firmly connected to one another in the example shown, i.e. out of one piece. For manufacturing and assembly reasons, however, these can consist of several individual parts connected by means not shown.

The tubular part 97 of the paint tube 2 is displaceable in the direction of the axis 115 in the bore 85. The seal 95 serves to seal the displacement space between part 97 and the hollow needle valve sleeve 1. The valve head 99 is arranged in the valve chamber 23 and has a smaller diameter than the same , but a larger diameter than the part 97. A valve cone 100 is formed between part 97 and valve head 99 and can be brought into contact with valve seat 20 by mutual displacement of parts 1 and 2. A bore 101 and a shoulder 102 in the valve head 99 together form a valve seat 19. The same can be brought into contact with the inner sealing cone 4 by relative displacement of the parts 1 and 2. The tubular part 97 has a bore 103 which extends from the shoulder 98 into the valve head 99. A separating web 8 (FIG. 11) with wedge-shaped ends is inserted in a sealing manner in wedge-shaped grooves 104 of the bore 103. This forms two chambers 105 and 106 along the color tube 2. At the end of the bore 103 facing the valve head 99, the insertion does not take place as far as the bottom of the bore, so that an intermediate space 107 is formed which connects the chambers 105 and 106.

At the rear end of the paint tube 2, a paint connection head 6 is screwed onto the threaded spindle 5 and by means not shown {e.g. Set screw) connected to it in a torsion-proof manner. A seal 108 seals the paint tube 2 from the paint connection head 6 on the shoulder 98. The separating web 8 penetrates with a wedge-shaped end 109 into the paint connection head 6. The latter has a connection 7 and a color return connection 10, which in turn are connected to the chambers 105 and 106 via bores 110 and 111.

A pair of pliers 26, which is only indicated, can be non-positively connected to the paint connection head 6 by means not shown in FIG. 1.

A torsion spring 9 is fastened on the one hand in the paint connection head 6 and on the other hand in the hollow needle valve sleeve 1.

A hue application device 11 is indicated in FIG. 1. This has a rear device part 113 and a front device part 114, which can be displaced relative to one another in the direction not shown in the direction of the axis 115. One shown only schematically here Compression spring 36 between parts 113 and 114 causes them to be pressed against one another in the direction of arrows 121 and 122. Ink applicator 11 is provided with an approximately hollow cylindrical insertion opening 112, into which hollow needle valve sleeve 1 can be inserted. The insertion path is limited by a cone 31 at the rear end 83 of the hollow needle valve sleeve 1 by the cone 31 making a frictional contact with a conical bore 32 in the rear part 113 of the device.

The sealing rings 92 and 94 seal against the inner wall of the insertion opening 112.

The insertion opening 112 ends in a surface 116. A bore 117 connects to the surface 116 and forms with it a valve seat 118, which in turn can be brought into contact with the outer sealing cone 3 by sliding the device parts 113 and 114 against one another.

A hollow shaft chamber 25 is formed between the surface 116 and the sleeve part 84 and is connected to the bores 88 and 117. The end of the bore 117 ends in a schematically illustrated atomizer nozzle 12.

Lines 119 and 120, shown schematically, are provided in the front device part 114. The line 119 is connected on the one hand to a flushing valve 21 and on the other hand to the collecting groove 14. The line 120 is connected on the one hand to a return valve 22 and on the other hand to the collecting groove 15. 14

The mode of operation of the hollow needle valve 81 shown in FIG. 1 is described below:

To a certain extent, the hollow needle valve 81 represents an exchange unit which is used in the color change system according to the invention in a paint application device which is equipped with an appropriately provided insertion opening 112. The hollow needle valve sleeve 1 serves as a valve housing and at the same time as the main needle, the sealing cone 3 of which blocks or opens the bore 117 located in front of the atomizing nozzle 12 and thus supplies the atomizing nozzle 12 with paint or flushing medium.

The lifting movement of the hollow needle valve sleeve 1, respectively. of the sealing cone 3 is produced with a handling device explained in more detail below in FIG. 4. This grips the hollow needle valve sleeve 1 on the holding groove 18 by means of the clamping device 17 and pushes it into the insertion opening 112 until the cone 31 lies in the conical bore 32. The compression spring 36 in the direction of arrow 122 generates the necessary contact pressure between the sealing cone 3 and valve seat 118 and thus closes this passage.

Each hollow needle valve 81 used in the color change system according to the invention is supplied with one and the same color. The connection 7 is connected via a hose (not shown) to an ink metering device which generates a constant color flow which, when the valve system 19, 4 is closed, within the hollow needle valve 81 from the connection 7 via bore 110, chamber 105, intermediate space 107, chamber 106 and bore 111 to the color return connection 10 follows. The color cycle is thus up to immediately before the sealing cone 3 acting as the main needle or the atomizer nozzle 12 guaranteed.

During the handling of the hollow needle valves 81, it is therefore important that the valve system 19, 4 is always and automatically closed in order to hermetically shut off the paint.

The valve system 19, 4, and thus the pressure of the sealing cone 3 on the valve seat 19, is closed by the torsion spring 9. This rotates the paint connection head 6 and thus the paint tube 2 connected to it clockwise and moves it through the threaded spindle 5 relative to the hollow needle valve sleeve 1 until the sealing cone 4 comes into contact with the valve seat 19 and the bore 101 is closed. When the valve system 19, 4 is closed, the valve system 20, 100 is open. In this valve position, flushing agent enters the valve chamber 86 via the flushing valve 21, line 119, collecting groove 14, bore 19 and spiral groove 13, and from there via the valve system 20, 100 into the valve chamber 23. This is cleaned, the flushing agent continuing passes through the bores 87, the opening 24 and the bores 88 into the hollow shaft chamber 25. This is rinsed through and also cleaned. When the valve system 3, 118 is closed, the detergent is expelled outside the hollow needle valve sleeve 1 through the spiral barrels 16 to the rear of the collecting groove 15 and through the open return valve 22.

By adapting the shape of the spiral groove 13 and spiral run 16, an optimal rinsing effect can be achieved.

However, if the valve system 3.118 is open, the return valve 22 and the valve system 4.19 are closed, the flushing medium passes through the bore 117 to the atomizing nozzle 12 and 16

cleans them, as well as the atomizing device, not shown in Fig. 1, e.g. Bell plate.

If paint is now to be atomized, the flush valve 21 and the return valve 22 must be closed, the control of which is carried out by means not shown in detail.

For the pre-closure, i.e. To open the valve system 4, 19 or to close the valve system 20, 100, the paint connection head 6 is rotated counterclockwise by means of the pliers 26. The hollow needle valve sleeve 1 is held by the tensioning device 17. With the paint connection head 6, the threaded spindle 5 is simultaneously rotated against the force of the torsion spring 9. The threaded spindle 5 unscrews from the internal thread 96 and causes an axial movement of the paint tube 2 relative to the hollow needle valve sleeve 1. This closes the valve system 20, 100 and the inflow of Detergent interrupted. The paint can now pass unhindered from the chamber 105 through the bore 101, valve system 4, 19 into the valve chamber 23 and through the bores 87, opening 24, bores 88, hollow shaft chamber 25, and valve system 3, 118 into the bore 117 and thus to the atomizer nozzle 12 .

2 shows an ink application device 28 which has the shape of a rotary atomizer. The same functional parts as used in FIG. 1 are used in some cases.

A hollow shaft 30 is installed in the paint applicator 28. It has a bore 123, which forms a front, first part of the insertion opening for the hollow needle valve 81 designed as a unit, as described in FIG. The latter is only partially shown in section. A housing 37 is firmly connected to the paint applicator 28 and the hollow shaft 30 in a manner not shown in detail. The housing

37 has a bore 124 which forms the rear second part of the insertion opening. An annular piston 33 is displaceably arranged in an annular groove 125 of the housing 37 in such a way that these parts together form a pressure chamber 126. Soft seals 128 and 129 seal the piston walls.

The annular piston 33 is connected to a flange 127 which has the conical bore 32 for receiving the cone 31 centrally. A spring sleeve is on an external thread 131

38 screwed on. Protrusions 132 and 133 serve as abutments of the compression spring 36. The latter causes a relative movement in the direction of the arrows 121 and 122 between the housing 37 and the spring sleeve 38. A spring-loaded pawl 34 is connected to the flange 127 in a manner not shown, that it is radially displaceable and comes into contact with the cone 31 or the holding groove 18, the hollow needle valve 81 being locked axially and non-rotatably relative to the ink application device 28 in its inserted position.

The pressure chamber 125 is connected via a bore 134 in the housing 37 and a line 135 to an outside control valve 35 which is shown schematically. The collecting groove 14 is connected to the flushing valve 21 via a bore 136 and the line 119. The collecting groove 15 is connected to the return valve 22 via a bore 137 and the line 120.

The ink application device 28 is connected to a schematically illustrated bell plate 137. This includes the bore 117 facing the end of the sealing cone 3. This is connected via a bore 138 and a chamber 40 to an atomizer device 39.

A changeover valve 139 is installed in line 119, which is controlled accordingly, either the flushing medium from the flushing valve 21 or compressed air from a blow-out valve 77 allows the inflow into the line 119.

The handling and mode of operation of the arrangement shown in Fig. 2 is as follows:

The hollow needle valve 81 is inserted into the paint application device 28 as described in FIG. 1 by means of the tensioning device 17. The paint application device 28 is held in place in a spray device (not shown). The mode of operation of the valve systems 3, 118 and 4, 19 and 20, 100 and the relative movements between the hollow needle valve sleeve 1 and the color tube 2 by means of the compression spring 36 and the torsion spring 9 are also the same, as described in FIG. 1.

Before each insertion or The removal process must be switched on via the control valve 35 compressed air to the pressure chamber 125 so that the annular piston 33 is pressurized with compressed air and moves against the spring force of the compression spring 36 in the direction of arrow 122. The power requirement can be preselected by means of a greater or lesser prestress of the compression spring 36 by means of the spring sleeve 38. The annular piston 33 causes the built-in hollow needle valve 81 and 81 to be raised and lowered. an opening or closing of the sealing cone 3 and thus a connection or disconnection of the ink supply or the flushing medium supply to the bell plate 137 according to the manner described in Fig.l. After the purging has taken place, the purging medium still located in the valve chamber 23, opening 24, hollow shaft chamber 25 and chamber 40 is blown out with compressed air. The blow-out air flows in advance from the blow-out valve 77 via the shuttle valve 139, the line 119, the bore 136, the collecting groove 14, the bore 91 and the spiral groove 13 into the valve chamber 23.

Before every color change, i.e. Changing the hollow needle valves 81, a flushing or a blow-out process in the manner described is necessary. Also in the arrangement shown in FIG. 2, the valve system 4, 19 must be closed before handling the hollow needle valves 81. The manner of this closing by the torsion spring 9 and the handling process with the tensioning device 17 has already been explained in FIG. 1. In addition, the tensioning device 17 inevitably releases the pawl 34, in a manner not shown, for releasing the hollow needle valve 81 in order to enable the latter to be removed from the ink application device 28.

3 shows a paint application device 41 which has the shape of an air atomizing spray gun or so-called HLVP gun. Some of the same functional parts as in FIGS. 1 and 2 are used.

The insertion opening 112 serves to receive the hollow needle valve 81 designed as a unit, as described in FIG. 1. The paint application device 41 has a gun body 140 which contains the functional parts and lines according to FIG. 2. In addition, there is a supply line 141 for the atomizing air. 20th

The mode of operation of this ink application device 41 is identical to that of the ink application device according to FIG.

4, 5 and 6 show a possible variant of a handling device 142 for hollow needle valves 81 with revolver magazine. A plurality of hollow needle valves 81 are removably mounted in a magazine 42. The number corresponds e.g. the colors required for application in a spraying line of an automobile plant, including any reserves. The number of twenty-four shown is exemplary and can be adapted to the necessary requirements by enlarging the magazine accordingly.

The magazine 42 consists of a magazine body 147 and a hollow cylindrical magazine drum 148 connected to it. The magazine body 147 is rotatably mounted on a central bearing axis 53 by means of roller bearings 44. The latter is fastened in a rotationally fixed manner to a connecting part 43, which is firmly connected to a paint applicator 28 according to FIG. 2. One according to FIG. 3 could also be used. The connecting part 43 is at the same time a structural unit of the entire handling device 142 and also carries a motor 45 with a drive wheel 144. The latter is part of an enveloping drive 46 which is connected to a drive wheel 145 which is fixedly connected to the magazine body 147. A stepper, servo or pneumatic motor can be used as the motor 45.

Markings 49 are made on the underside of the magazine body 147. One is assigned to each hollow needle valve 81. An optical or inductive signal generator 48 is arranged on the connecting part 43 such that it Markings 49 can recognize. Recesses 146 are also provided on the underside of the magazine body 147. One is assigned to each hollow needle valve 81. A locking mechanism 50 attached to the connecting part 43 engages in the recesses 146.

Each hollow needle valve 81 is a form-fitting holder

51 and a non-positive holder 52 assigned, which in turn are attached to the magazine drum 148. The form-fitting holder 51 serves as a clear position definition and the force-fitting holder for the static determination of the hollow needle valve receptacle.

The bearing axis 53 carries an ejection unit 54 at the upper end. This consists of a bearing body 143, a longitudinal guide part 55, which guides an ejector 56, and a pneumatic cylinder 57, which gives the ejector 56 a reciprocating movement. The ejector 56 is designed with two arms, with an upper arm 149 and a lower arm 150. The magazine drum 148 has between the holders 51,

52 of each hollow needle valve has an opening 151 which can be penetrated by the forearm 150 during the back and forth movement.

A guide frame 64 is built on the connecting part 43 (FIG. 6) and serves to support an upper spindle bearing 65 and a spindle motor 62. A spindle 61 is rotatably arranged on the one hand in the connecting part 43 and on the other hand in the spindle bearing 65. A second spindle 161 is also rotatably supported on the one hand in the connecting part 43 and is on the other hand connected to the spindle motor 62 in a rotationally fixed manner. Each spindle 61, 161 rotates in a spindle nut 60, which is fastened on a yoke plate 59 22

are. The two lifting spindles 61, 161 are driven by the spindle motor 62 via an enveloping drive 63, the yoke plate 59 depending on the direction of rotation of the spindle motor moving downwards or upwards in the direction of the arrow 152.

The clamping device 17 is firmly connected to the yoke plate 59. This has two clamping jaws 153 which can be actuated simultaneously by means of cylinders 154. The actuation is preferably pneumatic. The clamping jaws 153 engage in the holding groove 18 of the hollow needle valve 81.

The pliers 26 (FIG. 6), which causes the valve system 4, 19 to open and close, are likewise located on the yoke plate 59 and are actuated by pneumatic or electrical means, not shown.

The entire assembly parts mentioned are advantageously integrated in a common housing 66 and thus form a paint application device to be considered as a unit. As a result, wear or leak particles are retained in relation to the environment. In addition, the housing 66 serves not to influence the spray booth air flow and also to protect all components of the handling device 142 and the magazine 42 from paint mist.

The operation of the handling device 142 shown in FIGS. 4 to 6 is as follows:

The handling device 142 has the task of removing one in a specific and individual order from the hollow needle valves 81 stored in the magazine 42 and inserting the same into the inking device 28 or 41 that is firmly connected to the handling device 142. Depending on the magazine position of the hollow needle valve 81 selected, that is to say to be removed, the motor 45 rotates to the right or left, so that the rotation path of the magazine 42 is at most half a revolution. This is also necessary in order not to cause any twisting of the paint hoses connected to the individual hollow needle valves 81 or their paint connection heads 6 (not shown in FIGS. 4 to 6). The hollow needle valve 81 to be removed is rotated into a removal position 47 (FIG. 5). The signal transmitter 48 is responsible for the position determination and for the positioning. Depending on the type of motor 45 used, the removal position 47 approached can be mechanically locked with the locking mechanism 50 if necessary.

The ejection unit 54 is responsible for bringing the hollow needle valve 81, which is in the removal position 47, into a lowering position 58 (shown in dash-dot lines in FIG. 4). In this lowering position 58, the hollow needle valve 81 is centered on the axis 151 of the ink application device 28 underneath and thus of the insertion opening 112 (FIG. 1).

The stroke of the ejection unit 54 is constant and is ensured in its end positions by fixed stops (not shown in more detail) in the pneumatic cylinder 57. The upper arm 149 encompasses the hollow needle valve 81 in a form-fitting manner, the lower arm 150 encompasses it in a force-fitting manner. When moving out of the removal position 47 into the lowering position 58, the holder 51 is mechanically inevitably released in a manner not shown.

The clamping device 17 is in turn, shifted in height by means of the spindle motor 62 via the enveloping drive 63 Spindles 61, 161 and the yoke plate 59, in the height position that their previously extended clamping jaws 153 are at the same height as the holding groove 18. When the hollow needle valve 81 has reached the lowering position 58, the cylinders 154 are activated in such a way that the Insert the clamping jaws 153 into the retaining groove 18 of the hollow needle valve 81 until they are form-fitting and firmly clamp the latter. The pneumatic cylinder 57 of the ejection unit 54 is then activated such that the ejector 56 withdraws.

The spindle spindles 61, 161 are now driven by the spindle motor 62 in such a way that the clamped hollow needle valve 81 is displaced in the direction of arrow 155 against the inking device 28 and is inserted into its insertion opening 121 (FIG. 1) or into the bores 123, 124 (FIG. 2) . If the hollow needle valve 81 is in contact with the cone 31 and the pawl 34 holds the same, the cylinders 154 of the clamping device 17 are activated in such a way that the clamping jaws 153 loosen and extend.

The spraying process takes place in this position, as has already been described in FIG. 1. The yoke plate 59 and thus the tensioning device 17 remain in this position until the hollow needle valve 81 is subsequently removed from the ink application device 28.

If it is necessary to replace a hollow needle valve 81 used in the paint applicator 28 after the spraying process or color change, the same takes place in the reverse order to that described above.

All movement end positions of the parts listed in the abovementioned processes are not shown electrical or pneumatic initiators signaled.

7 to 9 and 12 show perspective schematic overall representations of ink application devices constructed as a unit, consisting of ink application device 28, magazine device 165 and handling device 142. These ink application devices are shown with different variants of arrangements of the magazines for the hollow needle valves 81, each only schematic exterior views of the cladding, ie the housing 66 are drawn. These have different geometrical shapes 66, 66a, 66b and 66c, corresponding to the magazine shapes indicated as indicated. With 115 the axes (Fig.l) of paint applicators 28 are designated, which can be designed according to Fig. 2 or 3.

The variant according to FIG. 7 uses a revolver-shaped magazine 42, as was described in FIGS. 4 to 6. The hollow needle valve 81 selected for replacement is brought into the removal position 47 by the magazine 42 which swings back and forth by 180 ^* . The ejection then takes place, in the direction of arrow 156, into the lowering position 58 and from there the insertion, in the direction of arrow 157, into the inking device 28. The axes of the hollow needle valve 81 in the removal position 47 or lowering position 58 are parallel and eccentric to each other.

The variant according to FIG. 8 uses a flat cassette magazine 67, in which the hollow needle valves 81 are magazined parallel to one another. The hollow needle valve 81 selected for the replacement is moved in the direction of the arrows 158 by transversely displacing the flat cassette magazine 67 Removal position 47 brought. The ejection and insertion into the ink application device 28 then takes place as in FIG. 7. The axes of the hollow needle valve 81 in the removal position 47 or lowering position 58 are here also parallel and eccentric to one another.

FIG. 9 shows a pivotable ring cassette magazine 68, in which the hollow needle valves 81 are magazined concentrically to the axis 115 of the ink application device 28. The hollow needle valve 81 selected for replacement is brought into the removal position 47 by the ring cassette magazine 68 which swings back and forth by 180 ^* . The ejection then takes place, in the direction of arrow 156, in the lowering position 58 and from there the insertion, in the direction of arrow 157, into the paint applicator 28. The axes of the standing in the removal position 47 or lowering position 58 Hollow needle valve 81 are parallel and eccentric to each other.

A further variant according to FIG. 12 is similar to that in FIG. 9, however, with a fixed ring cassette magazine 159, in which the hollow needle valves 81 are maganized concentrically to the axis 115 of the ink application device 28. A slide-in device 160, which is only hinted at, surrounds the ring cassette magazine 159. When the hollow needle valve 81 is selected, a slide 162 which rotates therein encircles the ring cassette magazine 159 until it has reached the hollow needle valve 81 selected for replacement. It is then ejected, in the direction of arrow 163, into the lowering position 58 and from there inserted, in the direction of arrow 157, into the inking device 28. The axes of the standing position in the removal position 47 or lowering position 58 Hollow needle valve 81 are parallel and eccentric to each other.

The advantage of this variant is that the paint hoses connected to the hollow needle valves 81 no longer have to perform a swiveling movement and only experience a back and forth movement. This significantly reduces wear and the risk of hose breaks.

10 shows a dye-rinsing medium diagram in connection with the invention. Each individual ink type has a separate ink supply line with a constant medium circuit, a so-called ink ring line 164. For the sake of simplicity, only five colors a to e are shown here. The effective number of colors n corresponds to that which is necessary for a spray line, e.g. twenty-four or thirty-two. The aggregate parts assigned to a specific color are each designated with the corresponding additional letters a to e.

Each color ring line 164 is assigned a separate circulation pump 69, which takes the color medium from a work container 70, which is also separate for each color. In the drawing, only one, for example the circulation pump 69a and working container 70a belonging to color a, is shown schematically.

The color ring lines 164 feed all of the bodywork spraying lines or paint applicators present in an automobile plant. Only one paint applicator 28 is shown in FIG. 10. Each ink application device 28 is connected to the color ring line 164 via a ring line tap 71. Thus, on a color ring line 164a all hollow needle valves 81a are connected with the same color assignment a. Color feed lines 72 are connected to the ring line tap 71. In order for the paint flow rate at the atomizing nozzles in the paint applicator 28 to give constant values, the medium pressures or the flow rates in the paint feed lines 72a to 72n must also have constant values. For this reason, metering devices 73 are necessary which are installed in the ink feed lines 72. A separate control device 73a to 73n is assigned to each color a to n in order to control the required pressure and or flow.

A magazine device 165 is equipped with the hollow needle valves 81. The type of magazine can be designed according to that of FIGS. 7 to 9 or 12.

Each hollow needle valve 81 is reconnected to the color ring line 164 via a color return line 74, a color return valve 75 and a return tap 80.

The ink application device 28 is connected to a main flushing medium line 79 via the line 119 and the flushing valve 21. The blow-out valve 77 connects a compressed air source 166 to the line 119 via a check valve 78. The line 120 connects the paint application device 28 via the return valve 22 to a collecting line 76 for returning used and contaminated flushing medium.

The ink supply lines 72 present between the metering device 73 and the hollow needle valves 81, and the color return lines 74 existing between the hollow needle valves 81 and the color return valve 75 expediently designed as flexible hose lines.

The operation of the arrangement shown in Fig. 10 is as follows:

All hollow needle valves 81b to 81e, which are located in the magazine 165, are closed on the front of the valve system 4, 19 (FIGS. 1 to 3). As a result, the ink medium flows around its separating web 8, via the chamber 106, the bore 111 and the ink return connection 10 into the ink return line 74 and, when the ink return valve 75 is open, back into the ink ring line 164.

A hollow needle valve 81a is used in the paint applicator 28 by the handling device 142 (not shown here) (FIGS. 4 to 6). If this does not have a spray function at the moment, its valve systems 4, 19 and 3, 118 are closed. In the process, the color a likewise flows, with the color return valve 75 open, from the hollow needle valve 81a back into the color ring line 164a. If the paint application device 28 is in a spraying function, the valve systems 4, 19 and 3, 118 are opened, and the color return valve 75 is closed. The paint a now penetrates to the atomizer device of the paint applicator 28.

If a color change is imminent, or the bell plate or the atomizing nozzle is contaminated, an appropriate rinsing is carried out. The pre-shut-off valve system 4, 19 of the hollow needle valve 81a closes, as described in FIG. 1. By opening the flushing valve 21, the nozzle cavities and the atomizing devices are flushed and the flushing medium occurs when the valve is open Main needle valve system 3,118 into the open and with closed valve system 3,118 and open return valve 22 back into the collecting line 76. The check valve 78 prevents the flushing medium from penetrating into the compressed air system or into the blow-out valve 77.

After each flushing, the flushed surfaces of the inner parts of the hollow needle valve 81a must be blown dry with compressed air. This takes place after the flushing valve 21 has been closed by opening the blow-out valve 77. When the drying process is complete, the hollow needle valve 81a can be exchanged for such a different color by means of the handling device 142.

After a short rinse, i.e. only the atomizer device was cleaned and there is no need to change the color by replacing the hollow needle valve 81a, it is necessary to press and push paint into the empty, flushed cavities before a new spraying process. For this purpose, the main needle valve system 3.118 and the color valve system 4.19 are opened only briefly. The system is then ready for another spraying process.

There is also the possibility for simple coating systems, for example a non-automated paint shop, to design the magazine in the form similar to a revolver magazine, a flat cassette magazine or a ring cassette magazine and to arrange it separately from the ink application device 28, 41. The latter are constructed in the same way as already described. However, no handling device is provided and the hollow needle valves 81 are removed from the magazine by manual operation and inserted into a permanently arranged or a manually operated ink application device 28, 41. The drive technology of the handling movements described can be electromechanical or pneumatic.

Claims

32 PATENT CLAIMS

1. A method for coating objects with frequently changing types of coating media, each type being removed from a working container and fed to a color ring line which is assigned to the medium type and is under constant circulation, and the coating media are used one after the other in a selected manner come, the selected coating medium being fed to a hollow needle valve in a paint applicator with atomizing device and thereby penetrating directly into the hollow needle valve up to the atomizing device that cleaning of the hollow needle valve and the atomizing device after use of the selected coating medium is also carried out by means of a flushing medium is carried out, characterized in that each type of coating medium is fed to one and always the same hollow needle valve (81) assigned to it and when changing the type of coating medium the hollow needle valve (81a) in the color application g device (28, 41) is indirectly separated from the same and is replaced by another hollow needle valve (81 b) corresponding to the subsequent coating medium.

2. The method according to claim 1, characterized in that the hollow needle valves (81) are separately and outside the paint applicator (28,41) magazine and indirectly in a selected manner one after the other in the paint applicator (28,41) and removed from the same become.

3. The method according to claim 1, characterized in that the flushing medium is fed to the paint application device (28, 41) and within the same to the hollow needle valve (81) used.

4. A device for carrying out the method according to one of claims 1 to 3, for coating objects with frequently changing types of coating media, with a working container for each coating medium and a number of color ring lines corresponding to the number of coating media, which with constant circulation of the ¬ arranged coating medium, and a paint application device with a hollow needle valve and an atomizer is provided, the paint application device being alternately connectable to the associated color ring line, that there is also a flushing medium container with a flushing medium supply line (119), which can be connected to the paint applicator (81), the hollow needle valve (28, 41) and the atomizing device (12 or 39), characterized in that a number of hollow needle valves (81) corresponding to the number of coating media is present, each by means of hose lines (72) with e is connected in the same and the same colored ring line (164) and the hollow needle valve (81a) in the paint applicator (28, 41) is separably stored therein and can be replaced.

5. Device according to claim 4, characterized in that outside of the paint application device (28, 41) and indirectly connected to the same, a magazine device (165) for receiving the hollow needle valves (81b & ff.) Mounted outside the paint application device (28, 41). is available.

6. Device according to claim 5, characterized in that the magazine device (165) is a revolver magazine (42).

7. Device according to claim 5, characterized in that the magazine device (165) is a flat cassette magazine (67).

8. Device according to claim 5, characterized in that the magazine device (165) is a rotatable ring cassette magazine (68).

9. Device according to claim 5, characterized in that the magazine device (165) is a fixed ring cassette magazine (159).

10. Device according to claim 4, characterized in that outside of the paint application device (28, 41) and indirectly connected to the same, a handling device (142) for replacing the hollow needle valves (81a) is present in the paint application device (28, 41).

11. The device according to claim 4, characterized in that outside of the ink application device (28, 41) and separately from the same a magazine device (165) for receiving the outside of the ink application device (28, 41) hollow needle valves (81b & ff.) Is present.

12. Device according to claims 4, 5 and 10, characterized in that the paint application device (28, 41), magazine device (165) and handling device (142) form a paint application device constructed as a unit with a common housing (66) .

13. Device according to claim 4, characterized in that the paint application device (28, 41) has an insertion opening (112), a hollow needle valve (81 a) being insertable therein and means (31, 32, 34) being provided that Hold and lock the hollow needle valve (81a) in the ink application device (28, 41) in the inserted position.

14. Device according to claim 4, characterized in that each hollow needle valve (81) is provided with a color connection (7) and a color return connection (10) which are connected to the corresponding color ring line (164).

15. The device according to claim 14, characterized in that a central bore (103) from the front (82) to the rear (83) end in the hollow needle valve (81) is provided, which has a radially inserted separating web (8) which the bore ( 103) divides into two chambers (105, 106), the first chamber (105) communicating with the paint connection (7) and the second chamber (106) communicating with the color return connection (10) and mutually via an intermediate space (107), such that the first chamber (105) is a passage for the coating medium up to just before the atomizing device (12 or 39) and the second chamber (106) is a passage in the coating medium circuit with constant circulation through the bores (7, 105, 107, 106 and 10).

16. Device according to claim 4, characterized in that in the front end (82) of each hollow needle valve (81) a first valve system (4, 19) as the end of the coating medium, a second valve system (20, 100) as the end of the flushing medium and a sealing cone (3) are integrated, 36

the sealing cone (3) being part of a third valve system (3,118) which interacts with the atomizer device (12 or 39).

17. The device according to claim 16, characterized in that each hollow needle valve (81) has a hollow needle valve sleeve (1) and an axially displaceable color tube (2,97) therein with the bore (103) and a threaded spindle system (96,5 ) and a torsion spring (9) are arranged such that the latter rotates and displaces the hollow needle valve sleeve (1) and the paint tube (2) against one another and closes the first valve system (4, 19).

18. Device according to claim 17, characterized in that the hollow needle valve sleeve (1) in the bore (85) enclosing the bore (85) has a spiral groove (13) which the flushing medium supply line (119) to the paint application device (28) with the second valve system (20, 100) connects, and on the outer casing (93) there is a spiral run (16) which connects the second valve system (20, 100) to the return line (120) of the flushing medium.

19. Device according to claim 13, characterized in that the paint application device (28, 41) has a spring system (36) and a piston system (33, 125) and these are displaceable and connected to one another in such a way that when the hollow needle valve (81 ) whose sealing cone (3), located at the front end, closes the third valve system (3,118).