JPH04367755A - Painting spray gun - Google Patents

Abstract

PURPOSE:To reduce the discharge of a washing thinner and paint into a painting booth in a washing process at the time of color replacement and to certainly prevent the environmental disruption due to the control of environmental pollution. CONSTITUTION:A paint supply passage 31 and a paint discharge passage 32 are provided to a nozzle main body 17 so as to communicate with each other within a paint nozzle 18. A paint supply pipe is connected to the paint supply passage 31 and a drain valve is provided to the paint discharge passage 32. By this constitution, a washing thinner can be discharged to an outside drain tank at the time of the washing of the paint supply pipe, the paint supply passage 31, the paint discharge passage 32 and the drain valve and the discharge amount of the thinner into a painting booth can be reduced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spray gun for spraying paint onto an object to be coated from a coating nozzle.

0002

[Prior Art] Generally, this type of painting spray gun (
A "spray gun" (hereinafter referred to as "spray gun") consists of a spray gun body, a paint nozzle provided at the tip side of the spray gun body, and an air nozzle provided at the tip of the paint nozzle that spouts out atomizing air and pattern air. , a paint valve provided on the base end side of the paint nozzle to open and close a needle valve body with respect to the paint nozzle; and a paint valve inserted into the needle valve body to apply a high voltage to the paint sprayed from the paint nozzle. a needle-like electrode provided with a tip end protruding from the paint nozzle;
It is generally composed of a paint supply pipe that supplies paint to the paint nozzle.

[0003] Paint is supplied to a paint nozzle provided at the tip of the spray gun body through a paint supply pipe and is sprayed from a paint spraying port of the paint nozzle. In addition, the atomizing air supplied from the spray gun body through the atomizing air passage in the paint nozzle is ejected from the atomizing air outlet provided in the air nozzle so as to surround the paint spraying opening, causing the paint to become mist. promote the development of Furthermore, the pattern air supplied from the spray gun body is ejected from pattern air outlets provided in the air nozzle, for example, vertically facing each other, so that the spray pattern of the paint is formed into an oval or oval shape, It evens out the coating on the object being coated.

[0004] Also, a specified high voltage (for example, -60 kV) is supplied to the needle-like electrode from a high-voltage generator provided externally through a high resistance provided within the spray gun body, and the needle-like electrode is A corona discharge region is formed on the tip side. This corona discharge region charges the paint sprayed from the paint nozzle and formed into a pattern by atomizing air and pattern air, and the paint flies toward the grounded object to be coated, increasing coating efficiency. It's supposed to improve.

[0005] Here, a conventional electrostatic atomizing spray gun for painting using a low-viscosity metallic paint will be described with reference to FIG. 10.

In the figure, reference numeral 1 indicates a spray gun body of a painting spray gun, and at the tip of the spray gun body 1 there is a nozzle head 2 consisting of a paint nozzle 2A and an air nozzle 2B.
The paint supplied to the paint nozzle 2A from the paint valve 4, which will be described later, is atomized from the paint spraying port of the paint nozzle 2A, and the sprayed paint is atomized by the atomizing air and pattern air jetted from the air nozzle 2B. The paint is pattern-formed and sprayed toward objects to be painted (none of which are shown) located within the painting booth.

Reference numeral 3 indicates a needle-shaped electrode, and the needle-shaped electrode 3 is provided so that its tip protrudes from the center of the paint nozzle 2A, and receives a high voltage from an externally provided high voltage generator (not shown). By supplying VH, a corona region is formed at the tip side of the air nozzle 2B, and the paint sprayed from the paint nozzle 2A is charged.

Reference numeral 4 indicates a paint valve provided in the spray gun body 1, and the paint valve 4 is connected between a paint supply pipe 5 and a paint nozzle 2A, which will be described later, to supply compressed air T. ON,
T. It constitutes a 2-port, 2-position air switching valve that can be switched by supplying and discharging the compressed air T. ON and compressed air T. By exhausting OFF, the paint valve 4 is switched to the switching position (A), and paint is supplied from the paint supply pipe 5 to the paint nozzle. On the other hand, compressed air T. OFF and compressed air T. By exhausting ON, the paint valve 4 is switched to the switching position (B), and the paint supply pipe 5 is switched to the switching position (B).
The supply of paint from the paint nozzle 2A to the paint nozzle 2A is stopped.

Reference numeral 5 indicates a paint supply pipe formed in a spiral shape, and the paint supply pile 5 is connected to the paint valve 4 and a color change valve device 6 (also called "CCV") provided externally.
The flow path is lengthened and connected to increase the flow resistance in the spray gun body 1, and from the color change valve device 6, metallic paints A color paint, B color paint, ... and cleaning thinner, Air is supplied to the nozzle head 2 as appropriate.

Reference numeral 7 indicates a drain valve provided in the spray gun body 1, and the drain valve 7 connects the color change valve device 6 to the paint supply pipe 5 at a connection point 8 and captures drained liquid from the outside. It is connected between the drain tank 9 and the drain tank 9. Further, the drain valve 7 is operated by compressed air D. It is configured as a 2-port, 2-position spring return type air switching valve that can be switched by ON supply/discharge.
Compressed air d. By supplying ON, the drain valve 7 is switched to the switching position (A), and paint etc. are discharged from the spray gun body 1 to the external drain tank 9. On the other hand, compressed air D. By discharging ON, the drain valve 7 is switched to the switching position (B), and the discharge of the coating amount etc. from the spray gun body 1 to the external drain tank 9 is prohibited.

Furthermore, since the paint supply side and the discharge side are connected to the ground at the end of the spray gun body 1, even when the high voltage VH is supplied to the needle electrode 3 at the connection point 8, the paint supply side is not connected to the ground at the end of the spray gun body 1. Since it is located on the paint inflow side of the pipe 5, it has an electrical potential of zero. Further, the drain valve 7 also becomes zero potential.

[0012] The paint spray gun according to the prior art is constructed as described above, and its operation will now be described using an example in which a metallic paint is used.

First, as a preparation process for painting, the paint valve 4 is set to the switching position (B) and closed, and the drain valve 7 is set to the switching position (A).
The valve is opened and A color paint is supplied from the color changing valve device 6. As a result, the A color paint is filled between the paint supply pipe 5 and the paint valve 4 and between the connection point 8 and the drain valve 7.

Next, in the painting process, the drain valve 7 is set to the switching position (B) and closed, and the atomizing air A and pattern air F are supplied to the air nozzle 2B, and the needle electrode 3
A high voltage VH is supplied to the In this state, the paint valve 4 is set to the switching position (A) and opened. As a result, the A color paint is supplied to the paint nozzle 2A, and is sprayed toward the paint booth from the paint spray port of the paint nozzle 2A. This atomized paint is pattern-formed by the atomizing air and pattern air of the air nozzle 2B, and is charged by the corona region formed by the needle-like electrode 3, and the paint flies toward the grounded object. This makes it possible to perform coating with high coating efficiency.

Furthermore, in order to spray the next color paint, for example, color B paint, it is necessary to clean the color A paint that has filled the paint nozzle 2A, paint valve 4, paint supply pipe 5, drain valve 7, etc. be. This is the cleaning process.

Therefore, in the cleaning process, the paint valve 4 is set to the switching position (B) and closed, and the drain valve 7 is set to the switching position (B).
a) to open the valve. In addition, high voltage VH to the needle electrode 3
At the same time, the supply of atomizing air A and pattern air F is also stopped. In this state, thinner and air are alternately and repeatedly supplied from the color change valve device 6 to the connection point 8 and from the color change valve device 6 to the connection point 8.
The A color paint and cleaning thinner remaining between the time and the drain valve 7 are all collected into the drain tank 9.

Next, the paint supply pipe 5, paint valve 4 and paint nozzle 2A are cleaned. Therefore, the paint valve 4 is set to the switching position (A) to open the valve, and the drain valve 7 is set to the switching position (B) to be closed. Then, thinner and air are alternately supplied from the color change valve device 6 for a short time, and the paint supply pipe 5
, the paint valve 4 and the paint nozzle 2A are swept away by the thinner and air, and the color A paint and thinner are discharged from the paint nozzle into the paint booth.

Then, as a preparation process for the next B color paint application, the paint valve 4 is closed, the drain valve 7 is opened, and the B color paint is transferred from the color change valve device 6 to the drain valve 7. supply Next, the paint valve 4 is opened, the drain valve 7 is closed, and the paint supply pipe 5 is opened.
B color paint is supplied between the time and the paint valve 4. Note that this is called a flushing process. As a result, the area between the paint supply pipe 5 and the paint valve 4 and between the connection point 8 and the drain valve 7 are filled with B color paint. In this way, next, the B color paint can be applied in the same manner as the A color paint application process as described above.

[0019] The above explanation of the operation is based on the case where metallic paint is used as the paint, but there are two main types of paint: solvent-based paints with a relatively high electrical resistance value and water-based paints with a small electrical resistance value. There are metallic paints in which metal powder is dispersed, but in water-based paints,
The needle electrode 3 is operated as a spray gun without being supplied with high voltage VH.

[0020] Also, depending on the viscosity of the paint, the paint supply pipe 5
make the shapes of That is, in the case of a low viscosity paint, it is formed in a spiral shape, and in the case of a high viscosity paint, it is formed in a straight shape to prevent a short circuit phenomenon from occurring due to the high voltage VH supplied to the needle electrode 3. ing.

[0021]

By the way, in the prior art painting spray gun described above, it is necessary to clean the paint supply pipe 5, paint valve 4, and paint nozzle 2A during the cleaning process, and it is necessary to use cleaning thinner. The amount of will increase. In particular, in the case of a spiral paint supply pipe 5, the paint flow path is long, so the amount of thinner increases. A large amount of cleaning thinner used in this cleaning and residual paint in the paint flow path are discharged into the paint booth, resulting in an increase in the cost of cleaning the paint booth and deterioration of the surrounding environment.

The present invention has been made in view of the problems of the prior art described above, and the present invention provides a coating method that can reduce the amount of paint and cleaning thinner discharged into the paint booth during cleaning in the color change process. The purpose is to provide a spray gun for

[0023]

[Means for Solving the Problems] A painting spray gun adopted by the present invention in order to solve the above-mentioned problems includes a spray gun body, a nozzle body provided at the tip side of the spray gun body, and a nozzle body. a paint nozzle provided at the tip of the main body to spray paint; an air nozzle provided at the tip of the paint nozzle to spray atomizing air and pattern air;
A paint valve is provided on the base end side of the nozzle body and opens and closes a needle valve body with respect to the paint nozzle by supplying and discharging compressed air; an atomizing air passage and a pattern air passage for supplying pattern air; a paint supply and discharge passage bored in the nozzle body for supplying and discharging paint to and from the paint nozzle and communicating within the paint nozzle; In order to connect the supply side passage of the supply/discharge passage and the outside of the spray gun body,
a paint supply pipe provided within the spray gun body;
and a drain valve provided on the spray gun body to open and close the discharge side passage of the paint supply and discharge passage.

[0024]

[Function] With the above configuration, during cleaning in the color change process, the paint supply and discharge passage and the paint supply pipe can be simultaneously cleaned with the paint valve closed, and at this time, any paint remaining in the paint supply and discharge passage and the paint supply pipe can be cleaned. And cleaning thinner can be drained to the outside via a drain valve.

[0025]

Embodiments Hereinafter, embodiments of the present invention will be explained based on FIGS. 1 to 9. In the embodiment, the same components as those in the prior art described above are given the same reference numerals, and their explanations will be omitted.

First, the overall structure of the painting spray gun will be explained based on FIGS. 1 to 3.

In the figure, reference numeral 11 indicates a spray gun body, which is formed of an insulating resin material into a long stepped cylinder shape, with a large diameter portion 11A on the tip side and a threaded portion on its outer peripheral surface. 11B is formed, and a cylindrical spray gun cover 12 is attached to the threaded portion 11B so as to cover the spray gun main body 11.
The inner peripheral surface of the resistance holder 1 serves as an insertion hole 11C, and the resistance holder 1 accommodates a rod-shaped resistor 13 having high resistance in the insertion hole 11C.
A high voltage VH is supplied to the resistor 13 from an externally provided high voltage generator (not shown), and the high voltage VH is applied to a needle electrode 27, which will be described later.

Further, on the tip side of the spray gun body 11, there is a nozzle body 17, which will be described later, a paint nozzle 18 provided at the tip of the nozzle body 17, and a retainer ring 23 on the tip side of the paint nozzle 18. Air nozzles 20 are provided in sequence.

Furthermore, the insertion hole 1 of the spray gun body 11
A paint valve 25, which will be described later, is located at the large diameter portion 11A of 1C.
is provided in the nozzle body 17, and a drain valve 34 is provided on the outer peripheral side of the spray gun body 11 on the proximal end side of the paint valve 25.

Reference numeral 15 indicates an end cover provided at the proximal end side of the spray gun body 11. The end cover 15 is formed of a thick plate, and as shown in FIG. Paint supply pipe mounting hole 15A, atomizing air supply pipe mounting hole 15B, pattern air supply pipe mounting hole 15C
, a paint discharge pipe mounting hole 15D, and a T. which controls the paint valve 25.
ON Supply pipe installation hole 15E, T. OFF supply pipe installation hole 1
5F, D. which controls the drain valve 34; ON Supply pipe installation hole 1
5G, a cleaning pipe attachment hole 15H for cleaning the drain valve 34, etc. are formed.

Reference numeral 16 indicates a mounting holder located below the end cover 15, and the mounting holder 16 is mounted to a reciprocator (none of which is shown) provided within the painting booth.

Next, the structure of the distal end side of the spray gun main body 11 will be explained based on FIGS. 4 to 6.

Reference numeral 17 indicates a nozzle body provided on the tip side of the spray gun body 11. The nozzle body 17 is formed into a stepped cylindrical shape, and its outer shape has a large diameter portion 17A on the tip side and a small diameter portion 17B on the base side. At the same time, the small diameter portion 17B and the large diameter portion 1
7A becomes the flange surface part 17C, and on the inner peripheral side, from the tip side, there is a paint nozzle fitting part 17D and a seal fitting part 17E, and on the outer peripheral surface of the large diameter part 17A on the tip side there is a male thread part 17F.
However, a female threaded portion 17G is formed on the inner peripheral surface.

Reference numeral 18 indicates a paint nozzle provided to fit into the paint nozzle fitting portion 17D of the nozzle body 17;
The paint nozzle 18 is molded from a single resin material, has a stepped cylindrical nozzle main body 18A, and is located at the proximal end of the main body 18A, communicating with an atomizing air passage 29 to be described later. The formed circumferential groove part 18B and the nozzle body 1 are formed in a tapered shape located on the proximal side of the circumferential groove part 18B.
Fitting part 18C fitted to paint nozzle fitting part 17D of No. 7
, a nozzle forming part 18D located on the tip side of the nozzle main body part 18A and protrudingly formed to have a small diameter, a valve seat 18E formed on the inner peripheral surface side of the nozzle forming part 18D, and the nozzle main body part A male threaded portion 18F is formed on the outer circumferential surface of the proximal end of the nozzle body 18A and is threadedly engaged with the female threaded portion 17G of the nozzle body 17, and an annular threaded portion 18F is formed on the distal end side of the nozzle main body 18A and is in contact with an air nozzle 20, which will be described later. It is generally composed of a tapered surface 18G and a plurality of atomizing air flow passages 18H, 18H, . Further, a needle valve body 26, which will be described later, is inserted into the inner peripheral surface of the paint nozzle 18 in the axial direction, and a paint flow passage 19 is formed between the needle valve body 26 and the needle valve body 26.

Reference numeral 20 indicates an air nozzle provided at the tip side of the paint nozzle 18, and the air nozzle 20 has a tapered recess 20A positioned on the tapered surface 18G, and a tapered recess 20A positioned on the tapered surface 18G so as to surround the nozzle forming portion 18D on the inside. A front wall portion 20B formed to cover the front side of the front wall portion 20A, horn portions 20C, 20C formed to face the upper and lower positions of the front wall portion 20B and protrude toward the tip side, and an outer peripheral surface. A locking step portion 20D is formed over the entire circumference of the retainer ring 20 and is locked to an engaging protrusion 23A of a retainer ring 23, which will be described later, via an annular ring 21 and a locking ring 22, and Pattern air flow passages 20E and 20 are formed from the base end side and communicate with a pattern air chamber 24, which will be described later.
E, pattern air jet ports 20F, 20F opening obliquely inward from each horn portion 20C, and a nozzle forming portion 18 of the paint nozzle 18 on the inner peripheral side of the front wall portion 20B.
Multiple atomizing air outlets 20G are provided surrounding D.
, 20G, . . .

Reference numeral 23 indicates a ring-shaped retainer ring, and an engaging protrusion 23 that engages with the air nozzle 20 via the annular ring 21 is provided on the inner peripheral side of the distal end of the retainer ring 23.
A is formed, and a nozzle body 1 is formed on the inner peripheral surface of the proximal end.
A female threaded portion 23B is formed which is screwed into the male threaded portion 17F of No. 7 to fix the paint nozzle 18 and the air nozzle 20. The nozzle body 17, paint nozzle 18, air nozzle 20, and retainer ring 23 constitute a nozzle head, and an annular pattern air chamber 24 is defined inside the nozzle head.

Reference numeral 25 indicates a paint valve located at the proximal end side of the nozzle body 17.
7, a piston 25B that is slidably provided in the cylinder 25A and defines two air chambers α and β, and an opening in the small diameter portion 17B of the nozzle body 17. A conductive spring 25D formed of a conductive material electrically connects the closing portion 25C and the piston 25B, and a conductive spring 25D inserted into the seal insertion hole 17E. The cylinder 25A (small diameter portion 17B) has a T. ON supply/exhaust port 2
The T.5F communicates with the air chamber β. An OFF supply/discharge port 25G is provided.

The paint valve 25 receives compressed air T. O
N., T. 2 ports 2 switched by OFF supply/discharge
The compressed air T. ON
T. ON Supplies compressed air into the air chamber α from the supply/exhaust port 25F. OFF to T. By exhausting air from the OFF supply/discharge port 25G, the paint valve 25 is switched to the open position of the switching position (A), as shown in FIG. On the other hand, compressed air T.
OFF to T. Compressed air is supplied into the air chamber β from the OFF supply/exhaust port 25G, and compressed air T. ON to T. ON By discharging air from the supply/discharge port 25F, the paint valve 25 is switched to the closed position of the switching position (B).

Reference numeral 26 indicates a needle valve body whose distal end extends to the nozzle forming portion 18D of the paint nozzle 18 and whose proximal end is fixed to the piston 25B, and the needle valve body 26 is formed in a cylindrical shape from a ceramic material. Valve part 2 is on the tip side
6A, and the valve portion 26A is connected to the valve seat 18 of the paint nozzle 18.
By moving the needle valve body 26 to and from the position E, the needle valve body 26 opens and closes with respect to the paint nozzle 18.

Reference numeral 27 indicates a needle-like electrode inserted in the axial direction of the needle valve body 26, and the tip side of the needle-like electrode 27 protrudes beyond the nozzle molding portion 18D of the paint nozzle 18, and is connected to the nozzle molding portion 18D. A paint spray port 28 is provided between the needle electrode 27 and the tip end thereof.

29, 29 are the large diameter portions 17 of the nozzle body 17
A shows an atomizing air passage formed obliquely in the axial direction, and each atomizing air passage 29 directs the atomizing air A from the spray gun body 11 to the circumferential groove 1 of the paint nozzle 18, as shown in FIG.
8B, and the atomizing air A is ejected from the atomizing air outlet 20G of the air nozzle 20 toward the outer circumferential side of the paint outlet 28 via the atomizing air flow path 18H.

30, 30 is the large diameter portion 17 of the nozzle body 17
A shows a pattern air passage formed obliquely in the axial direction,
As shown in FIG. 4, each pattern air passage 30 supplies the pattern air F from the spray gun body 11 to the pattern air chamber 24, and the pattern air flow passage 20 of the air nozzle.
Pattern air F is ejected from pattern air ejection port 20F via E.

31 and 32 are the large diameter portion 17 of the nozzle body 17
A shows a paint supply passage and a paint discharge passage which are formed obliquely in the axial direction, and these passages 31 and 32 are connected to the base end side of the paint nozzle 18 and the V-packing 25E of the paint valve 25, as shown in FIG. It opens into an annular chamber δ between the annular chamber δ and communicates with a paint flow passage 19 formed between the paint nozzle 18 and the needle valve body 26 at the position of the annular chamber δ.

Reference numeral 33 indicates a paint supply pipe, and as shown in FIGS. 1 and 2, the paint supply pipe 33 is provided so as to be wound around the outer periphery of the spray gun body 11, and is connected to the external color change valve device 6 ( 8) and the paint supply passage 31, and the paint supplied from the color change valve device 6 is transferred to the paint supply passage 31.
1 to the paint nozzle 18.

Here, the paint supplied to the paint flow passage 19 via the paint supply pipe 33 and the paint supply passage 31 is transferred to the paint spray nozzle 28 by opening the paint valve 25 at the switching position (A). sprayed from. Moreover, this sprayed paint is formed into a pattern by the atomizing air ejected from the atomizing air outlet 20G and the pattern air ejected from the pattern air outlet 20F, so that the paint is applied to the object to be coated. ing.

Next, based on FIGS. 1 and 7, the drain valve 3
The configuration of No. 4 will be described below.

That is, 34 indicates a drain valve provided in the middle to open and close the drain circuit 36 between the paint discharge passage 32 and the drain tank 9, and the drain valve 34 is open at the base end. A housing 34A is formed so as to have a cylinder inside, a valve body 34B is inserted in the axial direction of the housing 34A and has a valve portion 34B1 on the distal end side, and is integrally formed on the proximal end side of the valve body 34B. and said housing 3
a large diameter piston 34C that defines an air chamber γ within 4A;
A spring 34 that urges the piston 34C against the air chamber γ
D, and a lid portion 34E that positions the spring 34D and closes the opening of the housing 34A. The housing 34A has a discharged paint inlet passage 34F that communicates with the paint discharge passage 32, a discharged paint outlet passage 34G that communicates with the discharged paint inlet passage 34F via the valve portion 34B1 of the valve body 34B, and a compressed air D. ．． ON
D. is flowed into the air chamber γ. ON supply/discharge passage 34H is formed. Further, the discharged paint inflow path 34F communicates with the paint discharge path 32 of the nozzle body 17, and the discharged paint outflow path 34G communicates with the drain tank 9 provided outside the spray gun body 11 as shown in FIG. The circuit cleaning valve 41 is connected to the circuit cleaning valve 41, respectively. Here, the drain circuit cleaning valve 41 is the drain circuit cleaning valve 41.
The drain circuit 35 from the drain valve 34 to the discharged paint outlet path 34G and the drain circuit 36 from the discharged paint outlet path 34G to the drain tank 9 are cleaned.

The drain valve 34 is connected to the compressed air D. O
It is configured as a 2-port, 2-position spring return type air switching valve that is switched by supplying and discharging compressed air D.
．． ON to D. ON Air chamber γ via supply/discharge passage 34H
As shown in FIG.
is switched to the switching position (A), which is the valve open position, and the discharged paint inflow path 34F and the discharged paint outflow path 34G are communicated with each other, and paint etc. are discharged to the external drain tank 9. On the other hand, compressed air D. ON's D. ON By stopping the supply from the supply/drain passage 34H to the air chamber γ, the spring 34D switches the drain valve 34 to the switching position (B), the closed position, and paint etc. are discharged to the external drain tank 9. prohibited.

Further, 37 and 38 are compressed air T. ON
,T. Compressed air supply pipe for paint valve that supplies OFF,
39 supplies compressed air D. to the drain valve 34. The compressed air supply pipe for the drain valve that supplies ON is shown (see Figure 2).
0 indicates a positioning recess for positioning the spray gun body 11 and the nozzle body 17.

Furthermore, in FIG. 8, reference numeral 41 indicates a drain circuit cleaning valve provided outside the spray gun body 11, and the drain circuit cleaning valve 41 is configured to alternately supply air and thinner. As shown in FIG.
The inside of the drain circuit 36 from 4G to the drain tank 9 is cleaned.

In the end cover 15, although the paint supply pipe mounting hole 15A, the paint discharge pipe mounting hole 15D, and the cleaning pipe mounting hole 15H are connected to the ground, the needle electrode 27 is not supplied with high voltage VH. At this time, since the drain valve 34 is located on the paint inflow side of the paint supply pipe 33, the potential of the drain valve 34 is charged to a high voltage VH.

The spray gun for painting according to this embodiment has the above-mentioned structure, and its operation is shown in FIG.
and will be explained based on FIG.

First, the painting process using the A color paint will be explained. A color paint is supplied from the color change valve device 6 to the paint nozzle 18, and compressed air T. Supply ON,
Set to the switching position (A) to open the valve and spray the A color paint. Also, at this time, atomizing air A and pattern air F are ejected from the air nozzle 20, and a high voltage VH is applied to the needle electrode 27.
is supplying power. As a result, the paint sprayed toward the paint booth from the paint spray port 28 of the paint nozzle 18 is pattern-formed by the atomizing air A and pattern air F of the air nozzle 20, and the corona formed by the needle electrode 27 The area is electrically charged and the paint flies towards the grounded object to be coated, resulting in highly efficient coating.

When finishing painting the A color paint, compressed air T. is supplied to the paint valve 25. Stop the supply of ON and turn on the compressed air T. OFF is supplied, the switch is set to the switching position (B), the valve is closed, and the spraying of the A color paint from the paint nozzle 18 is stopped. Furthermore, the supply of high voltage VH to the needle electrode 27 is also stopped. On the other hand, the atomizing air A and pattern air F ejected from the air nozzle 20 are delayed to prevent the A color paint from adhering to the paint nozzle 18 and the air nozzle 20.

Next, the process moves to a cleaning process. In this process, compressed air D. Supply ON and switch position (a)
At the same time, air and thinner are alternately supplied multiple times from the color change valve device 6 to open the valve, and the paint supply pipe 33 is
, paint supply passage 31, annular chamber δ and paint discharge passage 32
Clean the area. At this time, the remaining A color paint and cleaning thinner are all discharged into the drain tank 9 via the drain valve 34 and the drain circuit 36. Meanwhile, during this cleaning step, the paint valve 25 is temporarily opened to clean the A color paint adhering to the paint flow path 19, paint spout 28, and needle electrode 27. At this time, unlike the prior art, not only the paint supply pipe 33 but also the paint supply passage 31 in the nozzle body 17, the vicinity of the annular chamber δ, the paint discharge passage 32, etc. have already been cleaned, so that the paint is not discharged into the painting booth. The amount of A-color paint and cleaning thinner used will be extremely small.

[0056] Furthermore, the process moves on to the preparation process for painting the next color B paint. In this process, B color paint is supplied from the color change valve device 6, and B color paint is filled up to the paint supply pipe 33, paint supply passage 31, paint flow passage 19, and paint discharge passage 32, and the B color paint is supplied from the drain valve 34. B even before drain tank 9
Feed until the color paint reaches. On the other hand, in the middle of this painting preparation process, the paint valve 25 is temporarily opened to spray a small amount of B color paint from the paint spout 28 to perform a flash process in preparation for B color painting.

Next, the process moves to the cleaning process of the drain circuits 35 and 36. In this embodiment, when a high voltage VH is supplied to the needle electrode 27, the drain valve 34 becomes a high voltage section VH, so if B color paint remains in the drain circuits 35 and 36, a short circuit with the ground may occur. Therefore, a cleaning process for the drain circuits 35 and 36 is required to prevent this. First, the supply of B color paint from the color change valve device 6 is stopped, and the drain valve 3
Compressed air to 4 D. Stop the supply of ON and move to the switching position (
b) and close the valve. And drain circuit cleaning valve 4
By supplying thinner and air from 1, cleaning the B color paint in the drain circuits 35 and 36 with cleaning thinner, and supplying air for a relatively long time, the B color paint in the drain circuits 35 and 36 is removed. and completely remove cleaning thinner. Further, just before the end of the cleaning process for the drain circuits 35 and 36, the supply of atomizing air A and pattern air F from the air nozzle 20 is started in preparation for the next painting process.

Then, the process moves on to painting the B color paint, and the B color paint is supplied from the color changing valve device 6 to the paint nozzle 18, and the compressed air T. Supply ON, switch to the switching position (A), open the valve, and spray the A color paint. Also, at this time, atomizing air A and pattern air F are ejected from the air nozzle 20, a high voltage VH is supplied to the needle electrode 27, and B
Apply colored paint.

Thus, according to this embodiment, the nozzle body 17 includes the paint flow passage 19 of the paint nozzle 18 and the annular chamber δ.
A paint supply passage 31 and a paint discharge passage 32 are formed so as to communicate with each other, and the paint supply passage 31 is connected to a color change valve device 6 provided outside the spray gun body 11 via a paint supply pipe 33. Since the paint discharge passage 32 is configured to be connected to the external drain tank 9 via the drain valve 34 and the drain circuit 36, the paint valve 25 is connected in the cleaning process at the time of color change.
With the valve closed and the drain valve 34 open, the color change valve device 6
By supplying cleaning thinner and air to the nozzle body 17 from the paint supply pipe 33, paint supply and discharge passage 31,
32 and drain valve 34 are cleaned. At this time, most of the discharged paint and cleaning thinner can be captured in the drain tank 9.

On the other hand, in cleaning the paint spray nozzle 28 of the paint nozzle 18, only a small amount of cleaning thinner is discharged into the paint booth during the cleaning process, so compared to the prior art, less cleaning material is left inside the paint booth. The amount of thinner discharged can be extremely small.

[0061] In the above embodiment, an electrostatic atomization type spray gun was described in which a high voltage VH was supplied to the needle electrode 27 depending on the type of paint, but the present invention is not limited to this. It can also be used as a paint spray gun without power supply; in this case, drain circuit 3
The cleaning steps 5 and 36 can be omitted.

Further, although the paint supply pipe 33 is constructed as a spiral pipe wound around the outer periphery of the spray gun body 11, it may be constructed as a straight paint supply pipe depending on the viscosity of the paint.

[0063]

As described in detail above, according to the present invention, a paint supply and discharge path is provided in the nozzle body so as to communicate within the paint nozzle in order to supply and discharge paint to and from the paint nozzle. The paint supply pipe installed inside the spray gun body is connected to the supply side passage of the passage, and the discharge side passage is equipped with a drain valve, so when changing colors, the paint supply pipe,
Most of the cleaning thinner used for cleaning up to the paint valve and drain valve is not discharged into the paint booth.
The thinner and paint can be discharged to a capture device outside the paint booth, and the amount of thinner and paint discharged into the paint booth can be minimized. In addition, it is possible to reduce the cost of cleaning the paint booth and reduce environmental damage.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a painting spray gun according to an embodiment of the present invention.

FIG. 2 is a partially cutaway plan view of the painting spray gun shown in FIG. 1, viewed from above.

3 is a right side view of the painting spray gun in FIG. 1. FIG.

4 is a sectional view taken from the direction of arrow IV-IV in FIG. 6. FIG.

5 is a sectional view taken from the direction of arrow V-V in FIG. 6. FIG.

6 is a right side view of the nozzle body in FIG. 4. FIG.

FIG. 7 is an enlarged sectional view showing the drain valve in FIG. 1;

FIG. 8 is a system diagram of a painting spray gun according to an embodiment.

FIG. 9 is an explanatory diagram showing a paint color changing process.

FIG. 10 is a system diagram of a conventional painting spray gun.

[Explanation of symbols]

11 Spray gun body 17 Nozzle body 18 Paint nozzle 20 Air nozzle 25 Paint valve 26 Needle valve body 28 Paint spray nozzle 29 Atomization air passage 30 Pattern air passage 31 Paint supply passage 32 Paint discharge passage 33 Paint supply pipe 34 Drain valve A Atomization air F Pattern air VH High voltage α, β, γ Air chamber δ Annular chamber

Claims (1)

[Claims] Claim 1: A spray gun body, a nozzle body provided at the tip side of the spray gun body, a paint nozzle provided at the tip of the nozzle body for spraying paint, and a paint nozzle provided at the tip of the paint nozzle. , an air nozzle that blows out atomizing air and pattern air; a paint valve that is provided on the base end side of the nozzle body and that opens and closes a needle valve body with respect to the paint nozzle by supplying and discharging compressed air; an atomizing air passage and a pattern air passage that are bored in the nozzle body and that supply atomizing air and pattern air to the paint nozzle; In order to connect a paint supply and discharge passage communicating within the nozzle, and a supply side passage of the paint supply and discharge passage to the outside of the spray gun body, a paint supply pipe provided inside the spray gun body and a paint supply and discharge passage connected to A spray gun for painting comprising a drain valve provided on the spray gun body to open and close a discharge side passage of the passage.