JP3754387B2 - Painting equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coating apparatus, and more particularly to a coating apparatus suitable for performing coating by applying a high voltage to a conductive paint such as a water-based paint.
[0002]
[Prior art]
Since the water-based paint does not contain an organic solvent, the waste liquid treatment is easy and environmentally friendly, and since it does not contain a dangerous substance such as an organic solvent, it is excellent in terms of preventing fire accidents. For this reason, the need as an intermediate coating or top coating is increasing instead of or together with an organic solvent-based coating.
[0003]
When electrostatic coating is performed by applying a high voltage to such a water-based paint, it is necessary to employ an external application system or an electrical insulation mechanism of a paint circuit (hereinafter referred to as a voltage block system), unlike organic solvent-based paints. (For example, refer to Japanese Patent No. 2790153).
[0004]
[Problems to be solved by the invention]
In the external application method, the paint particles sprayed and atomized by the coating machine are charged by applying a voltage from the external electrode and are not contact-charged in the paint circuit. It is less likely to flow through.
[0005]
However, the external application method has a problem that the coating efficiency is lower than the voltage block method, and the amount of paint used increases by about 10%. Also, in principle, the paint gun is likely to get dirty, and as a result, defects in the paint gun are liable to occur. Therefore, it is necessary to increase the cleaning frequency of the paint gun, which causes a decrease in productivity.
[0006]
On the other hand, as a conventional voltage block system, a relay paint tank insulation system is known in which the relay paint tank installed on the booth side is floated on an insulating stand so that the charging range is from the coating machine to the relay paint tank. Yes.
[0007]
However, when the number of paint colors is large, a large space is required on the booth side, and there is a problem that workability is poor when color change is frequently performed or when the amount of paint used is large.
[0008]
Therefore, a piston is provided in the paint hose that guides the paint to the paint gun, and the paint is supplied to the front of the piston and moved forward to supply the paint to the paint gun, and with the air filled behind the piston. There has been proposed one that insulates the applied voltage before and after the piston (see JP 2001-327897 A).
[0009]
By the way, in this painting device, the paint remains structurally between the piston advance limit and the painting gun, so it is necessary to clean it. However, the color is changed by retreating the piston and filling the cleaning liquid. There was a problem that time became long.
[0010]
[Means for Solving the Problems]
An object of this invention is to provide the coating device which can wash | clean the residual coating material between the advance limit of a piston and a coating gun efficiently.
[0011]
(1) In order to achieve the above object, according to the present invention, a paint gun to which a voltage is applied, a paint pipe for guiding the paint to the paint gun, and a slidable watertight condition in the paint pipe are provided. A coating device that includes a piston and a drive unit that moves the piston in the paint pipe, and injects the paint in front of the piston and moves the piston toward the paint gun during painting. ,
A valve unit provided between a paint inlet of the paint gun and a tip of the paint pipe;
The valve unit communicates with the paint passage, one end communicating with the paint introduction port of the paint gun and the other end communicating with the paint pipe, the first cleaning fluid passage communicating with the paint passage, and the paint passage. A waste valve, a first valve for opening and closing a paint passage communicating with the paint introduction port of the paint gun, a second valve for opening and closing the first cleaning fluid passage, and a third valve for opening and closing the waste liquid passage. A coating apparatus comprising a valve is provided (claim 1).
[0012]
In this coating apparatus, since the valve unit is provided between the paint introduction port of the coating gun and the tip of the paint pipe, the first valve, the second valve, and the third valve are used when changing colors. By selectively opening and closing the valve and supplying the cleaning fluid from the first cleaning fluid passage, the paint remaining between the piston advance limit and the paint gun is efficiently cleaned by an operation different from the paint piping. be able to.
[0013]
Specifically, the cleaning operation is performed by pushing out the residual paint between the piston and the paint gun by supplying air or cleaning liquid to the first cleaning fluid passage with the first to third valves opened. And clean the paint passage.
[0014]
(2) Although not particularly limited in the above invention, in the valve unit according to the above invention, a second cleaning fluid passage communicating with the painting gun side of the first valve and a fourth cleaning fluid passage that opens and closes the second cleaning fluid passage. These valves can be further provided (claim 3).
[0015]
In this coating apparatus, when the color is changed, the first valve, the second valve, the third valve, and the fourth valve are selectively opened and closed, and the first cleaning fluid passage and the second cleaning are performed. By supplying the cleaning fluid from the fluid passages, the residual paint between the piston advance limit and the paint gun can be efficiently cleaned by an operation different from the paint piping. In particular, since the cleaning path is divided into two systems of the first cleaning fluid path and the second cleaning fluid path, each cleaning can be performed in parallel and the cleaning time can be shortened.
[0016]
Specifically, in the cleaning operation, air or cleaning liquid is supplied to each of the first cleaning fluid passage and the second cleaning fluid passage with the first valve closed and the second to fourth valves opened. . Thus, the residual paint between the piston and the paint gun is pushed out by another system and discarded, and the paint passage is washed.
[0017]
(3) Although not particularly limited in the above invention, in the valve unit according to the above invention, a hollow having an outer diameter smaller than the inner diameter of the paint passage between the second valve and the tip of the paint pipe in the paint passage. A pipe may be provided, and the third valve may be provided so as to face a space between the hollow pipe and the inner wall of the paint passage (Claim 5).
[0018]
At this time, it is more preferable to provide a funnel-shaped incoming inclined portion at the tip of the paint passage on the paint pipe side.
[0019]
In this coating apparatus, a hollow tube having an outer diameter smaller than the inner diameter of the paint passage is provided between the second valve and the tip of the paint pipe in the paint passage, so that the paint passage between them is a so-called double pipe. It becomes a tube structure. Therefore, when the cleaning fluid is supplied from the first cleaning fluid passage, the cleaning fluid is injected into the front space of the piston after passing through the inner space of the hollow tube, thereby improving the cleaning performance of the residual paint on the front surface of the piston. It will be different. The cleaning fluid after cleaning passes through the external space of the hollow tube and is discarded from the third valve to the waste liquid passage. However, the fluid flows into the external space of the hollow tube by the funnel-shaped inlet inclined portion. It is prevented that the flow becomes smooth and stays.
[0020]
(4) Although not particularly limited in the above invention, in the valve unit according to the above invention, preferably at least one of the inlet of the first cleaning fluid passage, the outlet of the waste fluid passage, and the inlet of the second cleaning fluid passage. It is more preferable that after all the electrical insulation pipes are connected and the valve unit is cleaned, the electrical insulation pipes are filled with an insulating fluid such as air or an organic solvent (claims 2 and 4).
[0021]
The piping that supplies the cleaning fluid to the valve unit is an electrical insulation piping, and the electrical insulation piping is filled with the insulation fluid for cleaning, so that even if a high voltage is applied during the next color coating, the electrical It is possible to prevent current from leaking from the insulating pipe.
[0022]
(5) In the above invention, when a conductive paint is employed as the paint (claim 7), the effect of the present invention is more exhibited, but the invention can also be applied to a non-conductive paint. In particular, in the coating apparatus of the present invention, most of the paint in the paint pipe is pushed out, so that the number of parts that need to be cleaned during color change is remarkably reduced, and before the paint is adhered to the inner wall of the paint pipe by the sliding movement of the piston. Since the color paint is scraped off, the cleanliness becomes higher. As a result, it is possible to use a conductive paint and a non-conductive paint that should not be mixed.
[0023]
【The invention's effect】
According to the first to seventh aspects of the present invention, the residual paint between the piston advance limit and the paint gun can be efficiently cleaned by an operation different from the paint pipe cleaning operation. The shortening of the color change time can be achieved, and the production speed of the painting process can be increased.
[0024]
According to the third aspect of the present invention, since the cleaning path of the valve unit is divided into two systems of the first cleaning fluid passage and the second cleaning fluid passage, the cleaning can be performed in parallel. Further, the cleaning time can be further shortened and the cleaning property can be improved.
[0025]
According to the fifth aspect of the present invention, since the supplied cleaning fluid is jetted from the hollow tube to the front space of the piston, the cleaning performance of the residual paint on the front surface of the piston is improved.
[0026]
According to invention of Claim 6, the flow of the fluid to the external space of a hollow tube becomes smooth by the funnel-shaped inhalation | inclination part, and the residence of a residual coating material can be prevented.
[0027]
According to invention of Claim 2 and 4, even if a high voltage is applied in the case of the next color coating, it can prevent that an electric current leaks from the said electric insulation piping.
[0028]
According to the seventh aspect of the present invention, it is possible to use a conductive paint and a non-conductive paint, which should not be mixed, in the same paint pipe.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First embodiment
FIG. 1 is a schematic diagram showing a usage form of the coating apparatus of the present invention, FIG. 2 is a schematic configuration diagram showing an embodiment of the coating apparatus of the present invention, and FIG. 3 shows an embodiment of a valve unit according to the coating apparatus of the present invention. It is sectional drawing.
[0030]
As shown in FIGS. 1 and 2, the coating apparatus 1 according to the present embodiment includes a bell-type electrostatic coating gun 11 to which a high voltage of −90 kV to −60 kV is applied, and a paint for guiding the coating material to the coating gun 11. A paint pipe 12 having flexibility (hereinafter also referred to as paint hose 12), a color change valve unit 13 provided in the middle of the paint pipe 12, and for changing the color of the paint, A piston 14 that can slide in a watertight state inside the manifold 131 of the color change valve unit 13, a drive means 15 that moves the piston 14, and a valve unit 17 that is provided between the paint hose 12 and the paint gun 11, Have
[0031]
For example, as shown in FIG. 1, the painting apparatus 1 of this example can be mounted on a painting robot R and used in a painting line. In the example shown in the figure, a paint gun 11 is attached to a hand H of the painting robot R, a paint hose 12 is fixed to an arm A using a mount M, and a driving means 15 is disposed outside the painting booth. ing. A valve unit 17 to be described later is fixed to the arm A using a mount M2. The hose connected to the valve unit 17 is inserted into the arm A.
[0032]
In this case, it is preferable to install at least the driving means 15 outside the painting booth, and this is possible in the painting apparatus 1 of the present embodiment. This is due to the following reason. In other words, there is no problem if all paints used in the painting booth are non-solvent (non-dangerous), but in the case of a mixed line of solvent-based paint and non-solvent-based paint, it is used in the painting equipment. It is necessary to make the drive motor and electrical wiring to be explosion-proof, which increases the equipment cost. However, by installing drive motors 154 and 155 that require explosion-proof specifications outside the paint booth, it is not necessary to make these explosion-proof specifications even for mixed lines of solvent-based paints, thereby reducing costs. Can do. Further, the installation of the driving means 15 outside the painting booth also improves the maintenance workability.
[0033]
The bell-type electrostatic coating gun 11 has a trigger valve in the gun body. When the trigger valve is opened based on a command signal from the control device of the coating apparatus 1, the paint supplied from the paint hose 12 is changed to the gun body. The bell cup 111 provided at the tip of the bell cup 111 is rotated, and the bell cup 111 is rotated at a high speed, whereby the supplied paint is sprayed radially while being atomized from the tip edge of the bell cup 111. The coating gun 11 used in the present invention is not particularly limited, and is not limited to the bell-type electrostatic coating gun. All electrostatic coating guns such as an air atomizing electrostatic coating gun are used. Therefore, detailed illustration is omitted in FIGS. 1 and 2.
[0034]
The paint hose 12 according to the present embodiment has a left end connected to the inlet of the paint passage 171 of the valve unit 17 and a right rear end connected to the outlet of the color change valve unit 13 in FIG. When the paint hose 12 is used with the paint gun 11 attached to the paint robot R as shown in FIG. 1, the paint hose 12 bends according to the working posture of the paint robot R. It is preferable to have a flexibility made of a nylon-based, polytetrafluoroethylene-based, or urethane-based resin so that the piston 14 can move smoothly even if the hose is bent. However, if the paint pipe 12 can be straight within at least the moving range of the piston 14, it can be made of a metal such as stainless steel. In this case, it is necessary to insulate the outside of the metal such as stainless steel with a resin or the like.
[0035]
In addition, the paint pipe of the present invention is not limited, but the paint hose 12 is provided so as to surround the inner surface layer made of a material excellent in wear resistance and the reinforcing material for preventing the expansion due to the internal pressure of the pipe. And an outer surface layer formed of a flexible material provided so as to surround the coating hose 12 and capable of following the curvature of the paint hose 12.
[0036]
Incidentally, the length of the paint hose 12 can be appropriately set according to the amount of paint used. For example, the length of the paint hose 12 is long when the amount of paint used is large and is short when the amount of paint used is small.
[0037]
A color change valve unit 13 is connected to the right end of the paint hose 12, and each end of the manifold 131 and the paint hose 12 are watertightly connected by a joint. In the color change valve unit 13 shown in the figure, a switching valve 132 to which a different paint is supplied from a paint supply source (not shown), a switching valve 133 to which compressed air is supplied, and a cleaning liquid (for cleaning in the case of conductive paint). In the case of pure water or a non-conductive paint, a switching thinner 134 to which cleaning thinner is used (the same applies hereinafter) is provided. In the figure, the paint is supplied to the six switching valves 132 on the left side, but the number of the switching valves 132 may be more or less, and may be appropriately increased or decreased depending on various conditions such as the number of paint colors applied. Can do. The compressed air supplied to the switching valve 133 is used for extruding the paint and the cleaning liquid at the time of color change, and the cleaning liquid supplied to the switching valve 134 is used for the pipe cleaning at the time of color change.
[0038]
In the color change valve unit 13 of this embodiment, the inner diameter of the manifold 131 is formed substantially equal to the inner diameter of the paint hose 12. Accordingly, the piston 14 can smoothly move from the right end of the manifold 131 to the left end of the paint hose 12.
[0039]
Although there is no particular limitation in the present invention, the manifold 131 of the color change valve unit 13 is preferably made of an insulating material such as a synthetic resin, particularly when a conductive paint is used as the paint. If the manifold 131 is made of a conductive material such as metal, current may leak from the manifold 131 and the switching valves 132, 133, and 134 to the paint supply source side through the conductive paint.
[0040]
In the coating apparatus 1 of the present embodiment, a piston 14 that can slide in the watertight state from the right end of the manifold 131 of the color change valve unit 13 to the left end of the paint hose 12, and the piston 14 at an appropriate position and Drive means 15 for moving at an appropriate speed.
[0041]
As shown in an enlarged view in FIG. 3, the piston 14 has two O-rings 142 a and 142 b (hereinafter collectively referred to as “O”) that are made of an insulating material and prevent leakage of paint. The length of the piston body 141 in the axial direction is shortened as much as possible so that the paint hose 12 can move smoothly even if it is curved. The piston body 141 is preferably made of an insulating material that does not deteriorate with water or an organic solvent such as nylon, and the O-ring 142 is a material such as rubber having an appropriate elasticity, and has excellent wear resistance and solvent resistance. It is preferable to make it from a thing.
[0042]
This O-ring 142 not only ensures the watertightness of the paint and the like before and after the piston 14, but also functions to improve the sliding property of the piston 14, and further before the adhering to the inner wall of the paint hose 12 at the time of color change or the like. It also has a function to scrape color paint.
[0043]
In a state where such a piston 14 is retracted to the retreat limit position indicated by a two-dot chain line in FIG. 2, when paint is injected into the front space S3 and the piston 14 is advanced toward the paint gun 11, Since the conductive paint adhered to the inner wall is also scraped forward by the O-ring 142, only air is present behind the piston 14. Therefore, even if a high voltage is applied to the coating gun 11, it is blocked before and after the piston 14 and current is prevented from leaking to the rear end side of the paint hose 12.
[0044]
Although not particularly limited in the present invention, as shown in FIG. 3, one end of the piston main body 141 is partitioned by two O-rings 142 a and 142 b, the outer peripheral surface of the piston main body 141, and the inner wall of the paint hose 12. A through hole 143 is formed which opens to S1 and whose other end opens into a hollow cable 151 described later.
[0045]
Even if the paint filled in the space S3 in front of the piston 14 leaks over the O-ring 142a and leaks into the space S1 due to the deterioration or wear of the O-ring 142a due to the presence of the through-hole 143, the leaked paint remains through-hole. It reaches the inside of the hollow cable 151 via 143. Therefore, paint leakage can be detected by the paint detector 31 provided at the right end of the hollow cable 151 or the like.
[0046]
Returning to FIG. 1 and FIG. 2, the driving means 15 for moving the piston 14 is provided near the color change valve unit 13 and the hollow cable 151 whose tip is fixed to the piston main body 141 and sandwiches the hollow cable 151. Are provided with two pairs of extruding rollers 152 and 152 and a pulling device 153 that winds the hollow cable 151.
[0047]
The extrusion rollers 152 and 152 are respectively rotated by a drive motor (not shown) to apply a driving force to the hollow cable 151 mainly when the piston 14 moves forward toward the coating gun 11. When returning in the opposite direction, the holding of the hollow cable 151 is released to make it free. The extrusion roller 152 controls the extrusion amount of the paint accompanying the movement of the piston 14, and a conventionally required gear pump or the like is not necessary in this embodiment. In addition, since the two pairs of extrusion rollers 152 and 152 have a mechanical structure that sandwiches the hollow cable 151 and advances the piston 14, in principle, when the coating roller hose 12 ruptures, the extrusion roller 152 reaches the abnormal high pressure. To slip. Therefore, safety is further increased.
[0048]
On the other hand, the pulling device 153 rotates in both forward and reverse directions by a drive motor (not shown), and rotates so that the hollow cable 151 is fed out in the same direction when the piston 14 moves forward toward the coating gun 11. . Moreover, it functions when returning the piston 14 in the direction opposite to the coating gun 11 by rotating in the reverse direction. At this time, as described above, the extrusion roller 152 becomes free with respect to the hollow cable 151, so that the time required for the return operation of the piston 14 is shortened by the amount by which the rotational speed of the pulling device 153 is increased.
[0049]
The cable 151 of the present example employs a hollow cable and is configured to detect paint leakage as described above. However, the cable of the present invention is not limited to the hollow cable, and is a solid cable. There may be. The extrusion rollers 152 are not limited to two pairs, and may be a pair or three or more pairs.
[0050]
Incidentally, the hollow cable 151 is preferably made of an insulating material, but when a metal (conductive) cable is used for the cable 151 in order to increase rigidity and durability, an insulating coating layer is provided on the outer periphery of the cable 151. It is more preferable to form and prevent current from leaking through the cable 14 due to residual humidity, moisture, paint, etc. behind the piston 14.
[0051]
In particular, in this embodiment, a valve unit 17 is provided between the tip of the paint hose 12 and the coating gun 11. As shown in an enlarged view in FIG. 3, the valve unit 17 has a valve block 171. The right end of the valve unit 171 communicates with the paint hose 12, and the left end is a paint introduction port 112 of the paint gun 11. A paint passage 172 connected to is formed. A screw hole 175 for attaching a paint hose 174 reaching the paint introduction port 112 of the paint gun 11 is formed at the left end of the paint passage 172.
[0052]
In addition, a hollow tube 190 having a flange 189 at the left end is inserted and fixed between a first valve 176 (to be described later) and the paint hose 12 in the paint passage 172, whereby the paint passage 172 is The internal space 192 of the hollow tube 190 and the space 191 between the outside of the hollow tube 190 and the inner wall of the paint passage 172 are partitioned, and the space 191 communicates with a waste liquid passage 181 described later. In the example shown in the figure, a funnel-shaped inlet inclined portion 173 is formed at the right end of the outer space 191 of the hollow tube 190, and is thereby introduced from the first cleaning fluid passage 177 during the color change cleaning. After the cleaning liquid passes through the paint passage 172 and is sprayed toward the piston 14, the cleaning liquid is smoothly introduced into the external space 191 by the inlet inclined portion 173 and guided to the drain tank 22 through the waste liquid passage 181.
[0053]
The paint passage 172 is opened and closed by a first valve 176 provided in the middle thereof, whereby the supply of paint from the paint hose 12 to the paint gun 1 can be turned ON / OFF. As shown in the figure, the first valve 176 includes a valve seat 176a formed on the valve block 171; a valve body 176b that contacts and separates from the valve seat 176a; and a valve rod fixed to the valve body 176b. 176c, a piston 176d fixed to the valve stem 176c, and a cylinder 176e in which the piston 176d is inserted, and driving fluid (for example, air) outside the figure is supplied to the front and rear of the piston 176d in the cylinder 176e. Thus, the valve body 176b opens and closes the opening of the valve seat 176a.
[0054]
The valve block 171 is formed with a first cleaning fluid passage 177 communicating with the paint hose 12 side of the first valve 176 of the paint passage 172 described above. In the example shown in the figure, a screw hole 179 for attaching an insulating hose 178 reaching the switching valve unit 20 is formed at the right end of the first cleaning fluid passage 177.
[0055]
The first cleaning fluid passage 177 is opened and closed by a second valve 180 provided in the middle thereof, whereby supply of extrusion air and cleaning liquid from the switching valve unit 20 can be turned ON / OFF. As shown in the figure, the second valve 180 includes a valve seat 180a formed on the valve block 171; a valve body 180b that contacts and separates from the valve seat 180a; and a valve stem fixed to the valve body 180b. 180c, a piston 180d fixed to the valve stem 180c, and a cylinder 180e in which the piston 180d is inserted, and a driving fluid (for example, air) (not shown) is supplied to the front and rear of the piston 180d in the cylinder 180e. Thereby, the valve body 180b opens and closes the opening of the valve seat 180a.
[0056]
The valve block 171 is provided with a waste liquid passage 181 that communicates with the external space 191 of the hollow tube 190 on the paint hose 12 side of the first valve 176 of the paint passage 172 described above. In the example shown in the figure, a screw hole 183 for mounting the insulating hose 182 reaching the drain tank 22 is formed at the right end of the waste liquid passage 181.
[0057]
The waste liquid passage 181 is opened and closed by a third valve 184 provided in the middle thereof, whereby the supply of the waste liquid to the drain tank 22 can be turned ON / OFF. As shown in the figure, the third valve 184 includes a valve seat 184a formed on the valve block 171; a valve body 184b that contacts and separates from the valve seat 184a; and a valve rod fixed to the valve body 184b. 184c, a piston 184d fixed to the valve stem 184c, and a cylinder 184e into which the piston 184d is inserted, and driving fluid (for example, air) outside the figure is supplied to the front and rear of the piston 184d in the cylinder 184e. Thus, the valve body 184b opens and closes the opening of the valve seat 184a.
[0058]
Further, the valve block 171 is formed with a second cleaning fluid passage 185 that communicates with the paint gun 11 side of the first valve 176 in the paint passage 172 described above. In the example shown in the figure, a screw hole 187 for attaching the insulating hose 186 reaching the switching valve unit 21 is formed at the left end of the second cleaning fluid passage 185.
[0059]
The second cleaning fluid passage 185 is opened and closed by a fourth valve 188 provided in the middle thereof, whereby the supply of extrusion air and cleaning liquid from the switching valve unit 21 can be turned ON / OFF. As shown in the figure, the fourth valve 188 includes a valve seat 188a formed on the valve block 171; a valve body 188b that contacts and separates from the valve seat 188a; and a valve rod fixed to the valve body 188b. 188c, a piston 188d fixed to the valve stem 188c, and a cylinder 188e into which the piston 188d is inserted, and driving fluid (for example, air) outside the figure is supplied to the front and rear of the piston 188d in the cylinder 188e. Thus, the valve body 188b opens and closes the opening of the valve seat 188a.
[0060]
Incidentally, application of high pressure to the coating gun 11, switching of the trigger valve, switching of the switching valves 132, 133, 134 of the color change valve unit 13, operation of the driving motor of the push roller 152, operation of the driving motor of the pulling device 153, and Switching of each valve of the valve unit 17 is controlled by a control signal from a control device (not shown).
[0061]
In addition to a control signal sent from a management device (not shown), such a control device receives a detection signal from a position sensor for detecting the current position of the piston 14. The position sensor is disposed at a position where a detection signal is sent when the piston 14 is located behind the color change valve unit 13, that is, a position of the piston 14 indicated by a two-dot chain line in FIG. The position where the piston 14 is positioned slightly forward of the color change valve unit 13 (hereinafter also referred to as an applicable position), and the piston 14 is connected to the coating gun 11. It is desirable to provide it at a position (hereinafter also referred to as a forward limit position) that sends a detection signal when it is positioned at the forward limit, which is the position immediately before the valve unit 17.
[0062]
Next, the operation will be described.
FIG. 4 shows the procedure of one cycle from supplying the coating material to the coating apparatus 1 of the present embodiment, applying the coating material from the coating gun 11 to the object to be coated, and waiting for the next object to be coated. is there.
[0063]
First, painting starts from a state in which the piston 14 is in an applicable position. In this state, the piston 14 is positioned slightly in front of the color change valve unit 13, and the space S3 of the paint hose 12 extending from the piston 14 to the bell cup 113 is filled with the paint P to be applied to the article to be coated. ing. This filling amount is substantially equal to the amount of paint applied by the coating gun 11 as described above. Of the paint hose 12 behind the piston 14, the space S2 is filled with air. Further, the valve block 17 is in a state where the first valve 176 opens the paint passage 172 and the other valves, that is, the second valve 180, the third valve 184, and the fourth valve 188 are all closed. . As a result, the paint hose 12 communicates only with the paint hose 174 reaching the paint introduction port 112 of the paint gun 11 via the paint passage 172.
[0064]
From this state, a high voltage is applied to the coating gun 11 and the trigger valve 112 is opened (step 1). As a result, an electric current flows from the coating gun 11 to the conductive paint P. However, since the space S2 behind the piston 14 is filled with air, this exhibits the function of a so-called voltage block, and the front and rear of the piston 14 Is electrically insulated.
[0065]
Almost simultaneously with the opening operation of the trigger valve 112, the push roller 152 is actuated to feed the cable 151 and advance the piston 14 toward the coating gun 11. The opening operation of the trigger valve 112 and the pushing operation of the piston 14 are performed almost simultaneously. However, depending on the posture of the painting robot R, the bell cup 113 of the painting gun 11 may be sideways or obliquely upward. In order to stabilize the initial discharge amount and the atomization pattern, the pushing operation of the piston 14 may precede the opening operation of the trigger valve 112 by about 0.1 to 0.3 seconds. By doing so, particularly in the rotary atomizing paint gun, it becomes an effective means for countermeasures against paint sagging at the tip of the feed tube.
[0066]
The extrusion speed at the time of extruding the piston 14 is related to the discharge amount from the bell cup 113. That is, when the extrusion speed is increased, the discharge amount is increased, and when the extrusion speed is decreased, the discharge amount is decreased. Therefore, the optimum extrusion speed is sent from the control device to the driving means 15.
[0067]
When the piston 14 moves forward toward the coating gun 11, the paint P is supplied to the coating gun 11 as described above. However, the piston 14 reaches the forward limit position immediately before the valve unit 17, and is provided here. When detected by the sensor, the extrusion roller 152 and the pulling device 153 are stopped, and the application of the high voltage to the coating gun 11 is stopped, and the coating on the object to be coated is finished (steps 3 and 4).
[0068]
The subsequent operation is a color change cycle. If the color of the next object to be coated is the same color, the process jumps to step 12 without performing the following color change cycle.
[0069]
First, as shown in FIG. 3, the paint P remaining between the tip of the piston 14 and the coating gun 11 is washed in a state where the piston 14 is in the forward limit position. To this end, the first valve 176 is closed and the fourth valve 188 is opened. At the same time, the second valve 180 and the third valve 184 are opened (step 5). Then, extrusion air is supplied through the switching valve units 20 and 21 (steps 6 and 7).
[0070]
Extrusion air supplied via the switching valve 21 passes through the insulating hose 186 to the second cleaning fluid passage 185 and passes through the open fourth valve 188. Here, the fore-color paint P remains between the closed first valve 176 and the paint gun 11, but this is pushed out to the paint gun 11 with the previous extrusion air and discarded.
[0071]
Next, the cleaning liquid is supplied by switching the valve of the switching valve unit 21 (step 8). The cleaning liquid passes through the insulating hose 186 to the second cleaning fluid passage 185, and further passes through the open fourth valve 188 to the paint passage 172, the paint hose 174, and the paint gun 11, from here. Discarded. By continuing the supply of the cleaning liquid for a predetermined time, the paint passage 172 extending from the first valve 176 to the coating gun 11 can be cleaned.
[0072]
Next, the valve of the switching valve unit 21 is switched again to supply extrusion air (step 10). As a result, the cleaning liquid that has been filled in the insulating hose 186, the second cleaning fluid passage 185, the paint passage 172, the paint hose 174, and the paint gun 11 is pushed out of the paint gun 11 and discarded.
[0073]
Thereafter, the above steps 8 and 10 may be repeated a plurality of times. Finally, the extrusion air is supplied for several seconds, and the air is stored in the second cleaning fluid passage 185 and the insulating hose 186. Thereby, even if a high voltage is applied to the coating gun 1 during the next color coating, the current can be prevented from leaking through this path. Therefore, it is desirable to employ an insulating hose 186 and have a length of 3 m or more.
[0074]
On the other hand, the extrusion air supplied through the switching valve 20 passes through the insulating hose 178 to the first cleaning fluid passage 177 and passes through the opened second valve 180. Here, between the closed first valve 176 and the piston 14, the fore-color paint P including the internal space 192 and the external space 191 of the hollow tube 190 remains, but the second valve Since the extruded air that has passed through 180 is guided to the internal space 191 of the hollow tube 190, the paint P remaining therein is pushed out to the piston 14 side. The extruded front color paint P, the paint P remaining on the front surface of the piston 14 and the paint P remaining in the external space 191 of the hollow tube 190 are opened by the pressure of the extrusion air. It is pushed out to the 184 side, passes through the third valve 184, and is discarded into the drain tank 22 through the waste liquid passage 181 and the insulating hose 182.
[0075]
Next, the cleaning liquid is supplied by switching the valve of the switching valve unit 20 (step 9). This cleaning liquid passes through the insulating hose 178 to the first cleaning fluid passage 177, and further passes through the opened second valve 180 to the internal space 192 of the hollow tube 190. And it injects toward this piston 14 from this internal space 192. This injection cleans the tip of the piston 14 and prevents color mixing of the previous color paint. The cleaning liquid injected into the front space S3 of the piston 14 reaches the waste liquid passage 181 from the external space 191 of the hollow tube 190 through the third valve 184, and is discarded into the drain tank 22 through the insulating hose 182. . By continuing the supply of the cleaning liquid for a predetermined time, the paint passage 172 from the piston 14 to the first valve 176 can be cleaned. In addition, the flow of the cleaning liquid from the piston front surface space S3 to the outer space 191 of the hollow tube 190 is smoothed by the incoming inclined portion 173 formed at the right end of the paint passage 172.
[0076]
Next, the valve of the switching valve unit 20 is switched again to supply extrusion air (step 11). Thus, the insulating hose 178, the first cleaning fluid passage 177, the inner space 192 of the hollow tube 190, the front space S3 of the piston 14, the outer space 191 of the hollow tube 190, the waste liquid passage 181 and the insulating hose. The cleaning liquid filled in 182 is pushed out to the drain tank 22 and discarded. Thereafter, the above steps 9 and 11 may be repeated a plurality of times. Finally, the extrusion air is supplied for several seconds, and the first cleaning fluid passage 177 and the insulating hose 178 as well as the waste liquid passage 181 and the insulating property are supplied. Air is stored in each hose 182. Thereby, even if a high voltage is applied to the coating gun 11 during the next color coating, the current can be prevented from leaking through these paths. Therefore, it is desirable to employ insulating hoses 178 and 182 and to set the length to 3 m or more, respectively.
[0077]
In this example, in the cleaning steps of Step 5 to Step 11, an independent cleaning system is configured before and after the first valve 176, and each is cleaned in parallel, so that the cleaning time can be shortened accordingly. At the same time, cleaning performance is improved by cleaning separately.
[0078]
Returning to FIG. 4, when cleaning around the valve unit 17 is completed, the first valve 176 of the valve unit 17 is opened and the second to fourth valves 180, 184, 188 are closed. Then, the extrusion rollers 152 and 152 are made free, and the piston 14 is moved backward by rotating the pulling device 153 in the opposite direction (step 12). When the piston 14 moves backward, the air behind the piston 14 (right side in the figure) is compressed. Therefore, to make the operation of the piston 14 smooth, a dump valve or the like is provided and opened. Is preferred.
[0079]
When it is detected by the position sensor that the piston 14 has reached the retreat limit position (step 13), the switching valves 133, 134 of the color change valve unit 13 are alternately opened and closed, and the paint hose 12 in front of the piston 14 is opened. Cleaning liquid and extrusion air are supplied to the space S3 (step 14). However, in the coating apparatus 1 of this example, since the cleaning from the valve unit 17 to the coating gun 11 has been completed, the fore-color paint remaining on the inner wall of the paint hose 12 and the color change valve unit 13 is mainly cleaned. It is a step for. Therefore, if there is another cleaning means, this step 14 may be omitted.
[0080]
When the inside of the paint hose 12 becomes clean, one of the switching valves 132 of the color change valve unit 13 is opened to supply the next color paint P into the paint hose 12 in front of the piston 14 (step 15). At this time, the opening / closing timing of the switching valve 132 is controlled according to the amount of paint used, and the filling amount is suitable for the coating color. This minimizes the amount of paint that remains after disposal and is discarded.
[0081]
When the next color paint P is supplied, the extrusion rollers 152 and 152 and the pulling device 153 are driven to advance the piston 14 (step 16). When the position sensor detects that the piston 14 has reached the position where the piston 14 can be applied slightly ahead of the color change valve unit 13 (step 17), the push roller 152 and the pulling device 153 are stopped and the coating gun 11 is stopped. The trigger valve is closed and the next color painting start signal is awaited (step 18).
[0082]
The following effects can be expected from the coating apparatus 1 of the present embodiment.
First, since the piston 14 is provided in the paint hose 12 and the conductive paint P is supplied to the front of the piston 14 and pushed out to the paint gun 11, an air layer is formed behind the piston 14. This demonstrates the so-called voltage block function. Therefore, an existing bell-type electrostatic coating gun having a high coating efficiency can be used as it is, and both the use of a conductive paint and the improvement of the coating efficiency can be achieved. In addition, since the existing paint gun can be used as it is, there is no need to replace or modify the paint gun.
[0083]
Moreover, the discharge amount can be easily controlled by controlling the extrusion speed of the piston, and it can be replaced with an expensive device such as a gear pump that has been conventionally required, thereby reducing the equipment cost.
[0084]
Furthermore, since the paint can be pushed out to the trigger valve using the piston during the color change operation, the amount of paint discarded at the time of color change is minimized, which is advantageous in terms of environmental measures such as reduction of paint cost and waste liquid treatment. It becomes.
[0085]
In addition, the amount of paint used (discharge amount) per coating gun varies depending on changes in the coating cycle time, differences in objects to be coated, differences in coating color such as paint solids, differences in required quality such as film thickness, etc. In the coating apparatus of the embodiment, the length of the paint hose 12 is set to the maximum amount of paint used, and this is filled with an amount of paint as necessary. It can be handled flexibly.
[0086]
Furthermore, the coating apparatus 1 of this embodiment can be applied to not only conductive paints but also non-conductive paints.
[0087]
Further, since all the paint in the paint hose 12 is pushed out by the piston 14, the range that needs to be cleaned is remarkably reduced, thereby making it possible to clean the system in a short time. In addition, as a result of increased cleanliness, it is also possible to change the color of the conductive paint and the non-conductive paint with the same coating apparatus.
[0088]
Furthermore, in the coating apparatus 1 of the present embodiment, since the paint is filled in the paint hose 12 immediately before painting, the problem of pigment settling does not occur even with a metallic paint or a mica paint. In addition, the problem of pigment sedimentation is also eliminated when applied to a coating gun using a cartridge.
[0089]
In addition to this, a first through hole 143 is provided in the piston body 141, one end faces the space S1 partitioned by the two O-rings 142a and 142b, and the other end faces the first hollow cable 151a. Therefore, even if the paint filled in the front space S3 of the piston 14 leaks due to deterioration or wear of the O-ring 142a, the paint is detected by the paint detector 31 via the first through hole 143 and the hollow cable 151. Detected. Therefore, it is possible to inspect the deterioration and wear state of the O-ring 142 without disassembling the piston 14, and to prevent the paint from leaking.
[0090]
Furthermore, in the coating apparatus 1 of this embodiment, since the hollow pipe 190 is provided in the paint passage 172, the cleaning liquid supplied from the switching valve unit 20 is sprayed toward the piston 14, thereby the front space of the piston 14 The detergency of S3 is improved. In addition, since the incoming inclined portion 173 is formed at the right end of the paint passage 172, the cleaning liquid that has cleaned the front space S3 of the piston 14 is smoothly guided to the external space 191.
[0091]
Further, since the cleaning operation is performed in parallel before and after the first valve 176, the color change time can be shortened. Furthermore, since the insulating hoses 178, 182 and 186 are filled with air after the cleaning is completed, even if a high pressure is applied to the coating gun 11 during the next color coating, these insulating hoses 178, 182 and 186 are blocked. Leakage from here can be prevented.
[0092]
Second embodiment
FIG. 5 is an enlarged cross-sectional view of a valve unit 17 showing another embodiment of the coating apparatus of the present invention. In this example, the fourth valve 188, the switching valve unit 21, and the insulating hose 186 of the first embodiment are omitted as compared to the first embodiment described above. The same members as those shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0093]
Although the hollow tube 190 is provided in the paint passage 172 formed in the valve block 171 and the flange portion 189 of the first embodiment in FIG. 3 is omitted, the basic function is the first implementation. The internal space 192 of the hollow tube 190 serves as a passage for the paint, and the external space 191 of the hollow tube 190 communicates with the waste liquid passage 181 via the third valve 184.
[0094]
Next, the operation of this example will be described.
FIG. 6 shows a procedure of one cycle from supplying the coating material to the coating apparatus 1 of the present embodiment, applying the coating material from the coating gun 11 to the object to be coated, and waiting for the next object to be coated. is there.
[0095]
Since the operations from Step 1 to Step 4 in FIG. 4 are the same as those in the first embodiment described with reference to FIG. 4, the color change cycle in Step 5 will be described. If the color of the next object to be coated is the same color, the process jumps to step 9 without performing the following color change cycle.
[0096]
First, as shown in FIG. 5, the paint P remaining between the tip of the piston 14 and the coating gun 11 is washed while the piston 14 is in the forward limit position. For this, all of the first valve 176, the second valve 180, and the third valve 184 are opened (step 5). And extrusion air is supplied through the switching valve unit 20 (step 6).
[0097]
Extrusion air supplied through the switching valve 20 passes through the insulating hose 178 to the first cleaning fluid passage 177 and passes through the open second valve 180. Here, since the front-color paint P remains between the front space S3 of the piston 14 and the coating gun 11, the extrusion air that has reached the second valve 180 from here reaches the coating gun 11 side and the piston 14. Branch to the side and push out the residual paint respectively. That is, the extrusion air from the second valve 180 pushes the paint remaining between the paint passage 172 facing the second valve 180 and the paint gun 11 to the paint gun 11 and discards it. On the other hand, the extrusion air from the second valve 180 also removes the paint remaining between the paint passage 172 facing the second valve 180 and the piston 14 from the external space 191 of the hollow tube 190, the third valve. 184, the waste liquid passage 181 and the insulating hose 182 are pushed into the drain tank 22 and discarded.
[0098]
Next, the cleaning liquid is supplied by switching the valve of the switching valve unit 20 (step 7). This cleaning liquid also passes through the insulating hose 178 to reach the first cleaning fluid passage 177 and passes through the second valve 180 that is further open, like the above-described extruded air. Then, one side from here reaches the paint hose 174 and the paint gun 11 from the opened first valve 176 and is discarded from here. By continuing the supply of the cleaning liquid for a predetermined time, the paint passage 172 extending from the first valve 176 to the coating gun 11 can be cleaned. The other passes through the internal space 192 of the hollow tube 190 and injects toward the piston 14. Thereby, the washability of the front color paint remaining in the front space S3 of the piston 14 is improved. Then, the cleaning liquid injected into the front space S3 of the piston 14 reaches the waste liquid passage 181 from the external space 191 of the hollow tube 190 through the third valve 184, and is discarded to the drain tank 22 through the insulating hose 182. Is done. By continuing the supply of the cleaning liquid for a predetermined time, the paint passage 172 from the piston 14 to the first valve 176 can be cleaned. In addition, the flow of the cleaning liquid from the piston front surface space S3 to the outer space 191 of the hollow tube 190 is smoothed by the incoming inclined portion 173 formed at the right end of the paint passage 172.
[0099]
Next, the valve of the switching valve unit 20 is switched again to supply extrusion air (step 8). Thus, the insulating hose 178, the first cleaning fluid passage 177, the inner space 192 of the hollow tube 190, the front space S3 of the piston 14, the outer space 191 of the hollow tube 190, the waste liquid passage 181 and the insulating hose. The cleaning liquid filled in the paint passage 172 and the paint hose 174 on the coating gun 11 side from the 182 and the second valve 180 is pushed out to the drain tank 22 or the painting gun 11 and discarded. Thereafter, the above steps 6 and 7 may be repeated a plurality of times. Finally, the extrusion air is supplied for several seconds, and the first cleaning fluid passage 177 and the insulating hose 178 as well as the waste liquid passage 181 and the insulating property are supplied. Air is stored in each hose 182. Thereby, even if a high voltage is applied to the coating gun 11 during the next color coating, the current can be prevented from leaking through these paths. Therefore, it is desirable to employ insulating hoses 178 and 182 and to set the length to 3 m or more, respectively.
[0100]
In this example, since the cleaning system is constituted by the extrusion air and the cleaning liquid from one switching valve 20 in the cleaning steps of Step 5 to Step 8, the apparatus configuration and control are simplified by that much, and the cost is reduced. Also contribute to.
[0101]
Returning to FIG. 6, when cleaning around the valve unit 17 is completed, the first valve 176 of the valve unit 17 is kept open, and the second and third valves 180 and 184 are closed. Then, the extrusion rollers 152 and 152 are made free, and the piston 14 is moved backward by rotating the pulling device 153 in the opposite direction (step 9). When the piston 14 moves backward, the air behind the piston 14 (right side in the figure) is compressed. Therefore, to make the operation of the piston 14 smooth, a dump valve or the like is provided and opened. Is preferred.
[0102]
When it is detected by the position sensor that the piston 14 has reached the retreat limit position (step 10), the switching valves 133, 134 of the color change valve unit 13 are alternately opened and closed, and the paint hose 12 in front of the piston 14 is opened. Cleaning liquid and extrusion air are supplied to the space S3 (step 11). However, in the coating apparatus 1 of this example, since the cleaning from the valve unit 17 to the coating gun 11 has been completed, the fore-color paint remaining on the inner wall of the paint hose 12 and the color change valve unit 13 is mainly cleaned. It is a step for. Therefore, if there is another cleaning means, this step 14 may be omitted.
[0103]
When the inside of the paint hose 12 becomes clean, one of the switching valves 132 of the color change valve unit 13 is opened to supply the next color paint P into the paint hose 12 in front of the piston 14 (step 12). At this time, the opening / closing timing of the switching valve 132 is controlled according to the amount of paint used, and the filling amount is suitable for the coating color. This minimizes the amount of paint that remains after disposal and is discarded.
[0104]
When the next color paint P is supplied, the extrusion rollers 152 and 152 and the pulling device 153 are driven to advance the piston 14 (step 13). Then, when the position sensor detects that the piston 14 has reached the position where application is possible slightly ahead of the color change valve unit 13 (step 14), the push roller 152 and the pulling device 153 are stopped and the coating gun 11 is stopped. The trigger valve is closed, and the next color painting start signal is awaited (step 15).
[0105]
The following effects can be expected from the coating apparatus 1 of the present embodiment.
First, since the piston 14 is provided in the paint hose 12 and the conductive paint P is supplied to the front of the piston 14 and pushed out to the paint gun 11, an air layer is formed behind the piston 14. This demonstrates the so-called voltage block function. Therefore, an existing bell-type electrostatic coating gun having a high coating efficiency can be used as it is, and both the use of a conductive paint and the improvement of the coating efficiency can be achieved. In addition, since the existing paint gun can be used as it is, there is no need to replace or modify the paint gun.
[0106]
Moreover, the discharge amount can be easily controlled by controlling the extrusion speed of the piston, and it can be replaced with an expensive device such as a gear pump that has been conventionally required, thereby reducing the equipment cost.
[0107]
Furthermore, since the paint can be pushed out to the trigger valve using the piston during the color change operation, the amount of paint discarded at the time of color change is minimized, which is advantageous in terms of environmental measures such as reduction of paint cost and waste liquid treatment. It becomes.
[0108]
In addition, the amount of paint used (discharge amount) per coating gun varies depending on changes in the coating cycle time, differences in objects to be coated, differences in coating color such as paint solids, differences in required quality such as film thickness, etc. In the coating apparatus of the embodiment, the length of the paint hose 12 is set to the maximum amount of paint used, and this is filled with an amount of paint as necessary. It can be handled flexibly.
[0109]
Furthermore, the coating apparatus 1 of this embodiment can be applied to not only conductive paints but also non-conductive paints.
[0110]
Further, since all the paint in the paint hose 12 is pushed out by the piston 14, the range that needs to be cleaned is remarkably reduced, thereby making it possible to clean the system in a short time. In addition, as a result of increased cleanliness, it is also possible to change the color of the conductive paint and the non-conductive paint with the same coating apparatus.
[0111]
Furthermore, in the coating apparatus 1 of the present embodiment, since the paint is filled in the paint hose 12 immediately before painting, the problem of pigment settling does not occur even with a metallic paint or a mica paint. In addition, the problem of pigment sedimentation is also eliminated when applied to a coating gun using a cartridge.
[0112]
In addition to this, a first through hole 143 is provided in the piston body 141, one end faces the space S1 partitioned by the two O-rings 142a and 142b, and the other end faces the first hollow cable 151a. Therefore, even if the paint filled in the front space S3 of the piston 14 leaks due to deterioration or wear of the O-ring 142a, the paint is detected by the paint detector 31 via the first through hole 143 and the hollow cable 151. Detected. Therefore, it is possible to inspect the deterioration and wear state of the O-ring 142 without disassembling the piston 14, and to prevent the paint from leaking.
[0113]
Furthermore, in the coating apparatus 1 of this embodiment, since the hollow pipe 190 is provided in the paint passage 172, the cleaning liquid supplied from the switching valve unit 20 is sprayed toward the piston 14, thereby the front space of the piston 14 The detergency of S3 is improved. In addition, since the incoming inclined portion 173 is formed at the right end of the paint passage 172, the cleaning liquid that has cleaned the front space S3 of the piston 14 is smoothly guided to the external space 191.
[0114]
In addition, since the first valve 176 is cleaned with only one system of extrusion air and cleaning liquid, the configuration and control of the apparatus are simplified, which can contribute to cost reduction and can be expected to shorten the color change time. . Furthermore, since the insulating hoses 178 and 182 are filled with air after the cleaning is completed, even if a high pressure is applied to the coating gun 11 during the next color coating, the insulating hoses 178 and 182 are blocked by these insulating hoses 178 and 182 and leak from there. Can be prevented.
[0115]
The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a usage pattern of a coating apparatus of the present invention.
FIG. 2 is a schematic configuration diagram showing an embodiment of a coating apparatus of the present invention.
FIG. 3 is a cross-sectional view showing an embodiment of a valve unit according to the coating apparatus of the present invention.
4 is a flowchart showing an example of the operation of the coating apparatus of FIGS. 2 and 3. FIG.
FIG. 5 is a cross-sectional view showing another embodiment of the valve unit according to the coating apparatus of the present invention.
6 is a flowchart showing an example of the operation of the coating apparatus of FIG.
[Explanation of symbols]
1 ... Painting equipment
11 ... Paint gun
111 ... Bell Cup
112 ... Paint inlet
12 ... Paint hose (paint piping)
13. Color change valve unit
14 ... Piston
15 ... Drive means
151 ... Hollow cable
152 ... Extruding roller
153 ... Pulling device
17 ... Valve unit
171 ... Valve block
172 ... Paint passage
173 ... Inclined slope
176 ... first valve
177 ... first cleaning fluid passage
178 ... Insulating hose (electrically insulated piping)
180 ... second valve
181 ... Waste liquid passage
182 ... Insulating hose (electrically insulated piping)
184 ... Third valve
185 ... second cleaning fluid passage
186 ... Insulating hose (electrically insulated piping)
188 ... Fourth valve
190 ... Hollow tube
191 ... External space
192 ... Interior space

Claims (7)

A paint gun to which a voltage is applied, a paint pipe for guiding paint to the paint gun, a piston slidably provided in the paint pipe in a watertight state, and a driving means for moving the piston in the paint pipe In the painting device that injects the paint in front of the piston and moves the piston toward the painting gun at the time of painting,
A valve unit provided between a paint inlet of the paint gun and a tip of the paint pipe;
The valve unit communicates with the paint passage, one end communicating with the paint introduction port of the paint gun and the other end communicating with the paint pipe, a first cleaning fluid passage communicating with the paint passage, and the paint passage. A waste valve, a first valve for opening and closing a paint passage communicating with the paint introduction port of the paint gun, a second valve for opening and closing the first cleaning fluid passage, and a third valve for opening and closing the waste liquid passage. A painting apparatus comprising a valve. A cleaning fluid is supplied to the inlet of the first cleaning fluid passage through an electric insulating pipe, and the waste liquid reaching the outlet of the waste liquid passage is discarded through the electric insulating pipe. The coating apparatus according to claim 1, wherein the piping is filled with an insulating fluid. The coating apparatus according to claim 1, further comprising: a second cleaning fluid passage communicating with the coating gun side of the first valve; and a fourth valve opening and closing the second cleaning fluid passage. The coating apparatus according to claim 3, wherein a cleaning fluid is supplied to an inlet of the second cleaning fluid passage through an electric insulating pipe, and the electric insulating pipe is filled with an insulating fluid after the cleaning. A hollow tube having an outer diameter smaller than the inner diameter of the paint passage is provided between the second valve and the tip of the paint pipe in the paint passage.
The coating apparatus according to any one of claims 1 to 4, wherein the third valve is provided so as to face a space between the hollow tube and an inner wall of the paint passage. The coating apparatus according to claim 5, wherein a funnel-shaped inlet inclined portion is provided at a tip of the paint passage on the paint pipe side. The coating apparatus according to claim 1, wherein the paint is a conductive paint.

Images