JP4958412B2 - Painting equipment - Google Patents

Description

  The present invention relates to a coating apparatus, and more particularly to a coating apparatus suitable for use in, for example, blur coating of a vehicle body or the like of a vehicle.

The body of a vehicle such as an automobile is painted by spraying compressed air and paint at the same time and atomizing the paint. For this coating, a coating apparatus called a spray gun is preferably used.
As its name suggests, a spray gun is generally shaped like a small handgun, a paint supply part that supplies paint, a compressed air supply part that supplies compressed air, and a paint injection nozzle that serves as a paint injection port And a trigger portion for adjusting the amount of paint sprayed from the paint spray nozzle, and a spray gun body to which these are attached.
A rod-like valve having one end tapered and the other end connected to an elastic member such as a spring is inserted into the paint injection nozzle. This rod-shaped valve has a tapered end and opens and closes the injection port by sliding in the paint injection nozzle.
Further, the sliding movement of the needle valve is performed by moving the needle in the direction opposite to the urging direction by the trigger portion because the elastic member is urged in the direction to close the injection port.

Then, the closed injection port is opened, and the paint supplied from the paint supply unit and the compressed air supplied from the compressed air supply unit are simultaneously injected from the injection port. Then, the paint is atomized by the compressed air and adheres to the surface to be coated. When the paint is atomized, the painted surface can be dried quickly and a uniform painted surface can be obtained.
By the way, the types of painting include block painting for uniformly painting the surface to be painted, and blur coating for painting so that both the painted surfaces in which the surface to be painted and the old painted surface are mixed are uniform.
This blur painting is a painting technique in which painting is performed so as to obscure the boundary between the surface to be newly painted and the old painted surface where the previous painting remains and no new painting is necessary.
In spray guns with such a basic structure, some materials are easily clogged or divided due to diversification of paints that are spray materials. In a situation that cannot be achieved, that is, for example, when a paint mixed with carbon fiber is used, some of the contaminant components that are not dissolved in the paint are applied to the tapered surface of the needle valve and the sheet portion inside the paint outlet. There is a problem that a film or a lump is laminated to cause seal leakage or clogging.

In order to solve such a problem, in Japanese Utility Model Laid-Open No. 2-104856, a valve seat is formed on the inner surface of the injection port, and a needle valve having a tapered tip is brought into contact with and separated from the valve seat. The first and second tapered surfaces are formed inside the injection port formed in a cylindrical shape, line-contacted with the boundary between the first and second tapered surfaces, and the first taper angle and the second There has been proposed a needle valve device for a spray gun in which the taper surface of the needle valve is formed at an intermediate angle of the taper surface angle (Patent Document 1).
In addition, in order to perform the above-described blur coating with a spray gun, a skilled technique is required.
This is because the spray gun as described above cannot adjust the flow rate of compressed air, the opening area of the injection port, and the amount of paint at an appropriate balance at the time when the operation of the trigger portion is started. That is, immediately after starting operation of the trigger portion, the jet speed of the compressed air is low, but a predetermined amount of paint is supplied into the paint spray nozzle. Therefore, the sprayed paint has been sprayed with a large particle size, that is, not completely atomized. When the paint is sprayed without being completely atomized, there arises a problem that the thickness of the coating film becomes thick or the paint is difficult to adsorb on the painted surface.

As an invention made to cope with such a problem, there is a coating apparatus described in International Publication WO2002-10553 (Patent Document 2).
That is, in this patent document 2,
A coating device that mixes compressed air and paint, atomizes the paint and applies it to the surface to be coated,
The coating apparatus comprises a coating apparatus body provided with a compressed air supply passage for supplying compressed air and a paint supply passage for supplying paint;
A paint spray nozzle provided in the coating apparatus main body and having a spray port for spraying paint;
A paint adjusting means for opening and closing the injection port and adjusting the spray amount of the paint;
With
The paint adjusting means is a needle valve slidable inside the paint injection nozzle, and the needle valve has a tapered tip positioned on the injection port side, on the internal side of the paint injection nozzle, Comprising second and third taper portions that are continuous with the tip portion and have a predetermined length and different slopes;
A first taper portion and a second taper portion are continuously provided at predetermined positions on the inner wall of the paint injection nozzle corresponding to the tip portion and the two taper portions of the needle valve, with the injection port as an end portion. And
The first taper portion is a taper having a small diameter from the injection port toward the inside of the paint injection nozzle,
A coating apparatus is described in which the second taper portion is a taper portion whose diameter increases from the boundary line with the first taper portion toward the inside of the paint spray nozzle.

Therefore, in the coating apparatus according to Patent Document 2, the amount of paint sprayed immediately after pulling the trigger portion (generally “half-clutch” state) is adjusted by the gap between the second tapered portion and the tapered portion.
By the way, the spray guns are mainly used for block painting and blur painting.
Of these, there are not many problems with spray guns and workers in block painting, but there are major technical problems in blurry work.
Of the paints used in vehicle painting, the enamel-based solid type is relatively easy to work with, but aluminum pigments are complex in terms of reflection, absorption, and transmission characteristics. Therefore, when a blurring operation is performed using the paint, the drying property varies depending on the coating film in the color application state.
For this reason, a change in the color of the central portion occurs, which is extremely difficult for the operator. A typical example is the darkening of the blurred portion.
In order to suppress the occurrence of such darkening, it is necessary that the drying properties of the coating film at the center and the blur part be the same condition. Therefore, the half-open state in the blur part (hereinafter referred to as “half clutch”). It is considered to create a difference between the air pressure in the “state” and the air pressure in the central portion.

By the way, Patent Documents 1 and 2 described above include a needle valve having a plurality of tapered surfaces on the inner side of the injection nozzle and a paint injection nozzle having a tapered surface corresponding to the tapered portion of the needle valve. Although a needle valve device for a spray gun has been described, no consideration has been given to the drying properties of the coating film and the atomization of the particles in the central part and the blur part.
In other words, Patent Document 1 merely attempts to improve sealing performance and prevent clogging of the flow path. Moreover, in patent document 2, it is only aiming at making the spray state of a coating material favorable, eliminating the waste of coating material, and facilitating coating operation.
For example, at the beginning of the opening of the needle valve, the air pressure suddenly increases from zero, and the adjustment range of the pressure can be performed only in a very limited narrow range, and it is extremely difficult to generate a desired pressure. It was an intention. Therefore, in the so-called half-clutch state in which the needle valve is half-opened, the air pressure remains high despite the decrease in the amount of paint sprayed. There is a defect.
Accordingly, it has been difficult for a skilled coating technician to make the coating film gradually smooth from the central portion to the blurred portion while keeping the central portion and the blurred portion in the dry state.

Japanese Utility Model Publication No. 2-104856 International Publication Number WO2002 / 100553

The present invention has been made in view of the above circumstances, and has a wide air pressure adjustment range from the closed state of the air pressure adjusting means to the fully open state, and is easy to adjust. Combined with easy adjustment of the amount, it is easy to make the dry state of the block part (center part) and the blur part in particular, and the coating film thickness gradually forms from the center part to the blur part. It is in providing the coating apparatus which can do.
In addition, the present invention is to provide a coating apparatus that is capable of performing coating without darkening not only by skilled coating technicians but also by relatively beginners.

The invention described in claim 1 is a coating apparatus that mixes compressed air and a paint, atomizes the paint, and applies it to the surface to be coated.
The coating apparatus comprises a coating apparatus body provided with a compressed air supply passage for supplying compressed air and a paint supply passage for supplying paint;
A paint spray nozzle provided on the main body of the coating apparatus and having a spray nozzle for spraying paint;
Air pressure adjusting means for opening and closing the compressed air supply passage and adjusting the compressed air pressure;
A paint adjusting means for opening and closing the injection port and adjusting the spray amount of the paint;
With
The air pressure adjusting means is provided integrally with a valve portion capable of continuously changing a cross-sectional area of the compressed air supply passage from zero to a predetermined amount, and a cross-sectional area of the compressed air supply passage provided downstream of the valve portion. An air restricting section that reduces the pressure by a predetermined amount and configured to operate the paint adjusting means and the air adjusting means in conjunction with each other ,
When the air pressure adjusting means and the paint adjusting means are both in a half-open state, the air restricting section is configured to reduce the pressure so as to be a pressure that matches the amount of paint sprayed .

The air pressure adjusting means according to a second aspect of the present invention has a truncated cone shape in which the valve portion contacts and separates from a tapered portion formed on the inner side of the compressed air supply passage, and the air restricting portion is a circular shape. It is characterized by a plate shape.
The paint adjusting means according to the invention described in claim 3 is a needle valve slidable inside the paint injection nozzle, and the needle valve has a tapered tip positioned on the injection port side, An injection amount limiting portion having a predetermined length and the same diameter that is continuous with the tip portion on the inner side of the paint injection nozzle and having a certain play amount, and further continues to the injection amount limiting portion and faces the inside of the nozzle. The on-off valve portion has a large diameter with a gentle slope, and a shaft portion that is continuous with the on-off valve portion and restricts axial sliding.
The air pressure adjusting means and the paint adjusting means according to the invention described in claim 4 are urged by an elastic member in a direction to close the compressed air supply passage and the injection port, respectively. It is characterized in that it is moved in the opening direction in accordance with the operation of pulling the trigger portion against the force.

The invention described in 請 Motomeko 5 mixes the compressed air and paint to atomize the paint a painting device to be applied to the surface to be coated,
The coating apparatus comprises a coating apparatus body provided with a compressed air supply passage for supplying compressed air and a paint supply passage for supplying paint;
A paint spray nozzle provided on the main body of the coating apparatus and having a spray nozzle for spraying paint;
Air pressure adjusting means for opening and closing the compressed air supply passage and adjusting the compressed air pressure;
A paint adjusting means for opening and closing the injection port and adjusting the spray amount of the paint;
With
The paint adjusting means and the air pressure adjusting means are respectively provided on the same axis of a needle valve that is slidable inside the paint injection nozzle,
The needle valve has a tapered tip positioned on the injection port side,
An inside of the paint spray nozzle, having a predetermined length that is continuous with the tip and adding a certain play amount and having the same diameter, and is further continuous with the spray amount limiter and inside the nozzle An opening / closing valve portion having a large diameter with a gentle inclination toward the opening, and an air restriction portion that is coaxial with the opening / closing valve portion and that reduces the cross-sectional area of the compressed air supply path by a predetermined amount, and is continuous therewith. the cross-sectional area of the compressed air supply passage from zero and continuously changeable valve portion over a predetermined amount, Ri Na provided a series,
When the air pressure adjusting means and the paint adjusting means are both in a half-open state, the air restricting section is configured to reduce the pressure so as to be a pressure that matches the amount of paint sprayed .

According to a sixth aspect of the present invention, the air pressure adjusting means has a truncated cone shape in which the valve portion contacts and separates from a tapered portion formed on the inner side of the compressed air supply passage, and the air restriction portion is the compression portion. It is characterized by an annular shape provided with a predetermined gap between the inner wall of the air supply passage.
In the needle valve and the paint injection nozzle according to the invention described in claim 7 , the paint injection amount continuously changes at least in the first half of the movement stroke of the trigger portion, and in the remaining movement stages. It is characterized in that the spraying amount of paint is set to be substantially the same or slightly changed, and is suitable for blurry painting work.

According to the first aspect of the present invention, there is provided a coating apparatus that mixes compressed air and a paint, atomizes the paint, and applies the paint to a surface to be coated.
The coating apparatus comprises a coating apparatus body provided with a compressed air supply passage for supplying compressed air and a paint supply passage for supplying paint;
A paint spray nozzle provided on the main body of the coating apparatus and having a spray nozzle for spraying paint;
Air pressure adjusting means for opening and closing the compressed air supply passage and adjusting the compressed air pressure;
A paint adjusting means for opening and closing the injection port and adjusting the spray amount of the paint;
With
The air pressure adjusting means is provided integrally with a valve portion capable of continuously changing a cross-sectional area of the compressed air supply passage from zero to a predetermined amount, and a cross-sectional area of the compressed air supply passage provided downstream of the valve portion. An air restricting section that reduces the pressure by a predetermined amount and configured to operate the paint adjusting means and the air adjusting means in conjunction with each other ,
When the air pressure adjusting means and the paint adjusting means are both in a half-open state, the air restricting portion is depressurized so that the pressure is suitable for the amount of paint sprayed , so the valve portion of the air pressure adjusting means is closed. The range of the intermediate stage from the open state to the fully open state is wider than that in the past, and the pressure change is adjusted by the paint adjusting means to the pressure suitable for the state where the paint injection amount is reduced as the so-called half-clutch state. It is possible to blur the boundary between the old painted surface and the surface to be painted, and it is very easy to perform blur painting. Especially, the dryness and miniaturization of the blurred surface can be made to the same level as the old painted surface, which is avoided in the conventional equipment Thus, it is possible to provide a coating apparatus that can prevent the occurrence of darkening in the blurred portion, which has been difficult to achieve.

According to a second aspect of the present invention, the air pressure adjusting means has a truncated cone shape in which the valve portion contacts and separates from a tapered portion formed on the inner side of the compressed air supply passage, and the air restriction portion is Since it has a disk shape, it is a small and simple mechanism, can be easily incorporated into the apparatus main body, and can provide a coating apparatus that hardly increases the manufacturing cost.
According to a third aspect of the present invention, the paint adjusting means is a needle valve that is slidable inside the paint injection nozzle, and the needle valve has a tapered tip formed on the injection port side. An injection amount limiting unit having a predetermined length and the same diameter, which is continuous with the tip portion and added with a certain play amount on the inner side of the paint injection nozzle, and is further continuous with the injection amount limiting unit. The on-off valve portion that becomes large in diameter with a gentle inclination toward the inside of the inside, and the shaft portion that is continuous with the on-off valve portion and restricts the sliding in the axial direction. The spray paint can be sprayed more slowly than the conventional one in the intermediate region from the fully open state to the half-clutch state, so that the atomization can be surely realized, and the half-clutch state by the air pressure adjusting means described above And its structure It is possible to provide a coating apparatus which can be adapted.

According to a fourth aspect of the present invention, the air pressure adjusting means and the paint adjusting means are urged by elastic members in directions to close the compressed air supply passage and the injection port, respectively. Since it is configured to move in the opening direction in accordance with the operation of pulling the trigger portion against the urging force, the elastic member is attached in the initial state of pulling the trigger portion, so-called half-clutch state. Since the force is weak, a fine stroke can be given to the air adjusting means and the paint adjusting means, and the interaction with the invention of claim 1 can provide a coating apparatus suitable for blur painting .

According to the invention described in claim 5 , a coating apparatus that mixes compressed air and a paint, atomizes the paint, and applies it to the surface to be coated,
The coating apparatus comprises a coating apparatus body provided with a compressed air supply passage for supplying compressed air and a paint supply passage for supplying paint;
A paint spray nozzle provided on the main body of the coating apparatus and having a spray nozzle for spraying paint;
Air pressure adjusting means for opening and closing the compressed air supply passage and adjusting the compressed air pressure;
A paint adjusting means for opening and closing the injection port and adjusting the spray amount of the paint;
With
The paint adjusting means and the air pressure adjusting means are respectively provided on the same axis of a needle valve that is slidable inside the paint injection nozzle,
The needle valve has a tapered tip positioned on the injection port side,
An inside of the paint spray nozzle, having a predetermined length that is continuous with the tip and adding a certain play amount and having the same diameter, and is further continuous with the spray amount limiter and inside the nozzle An opening / closing valve portion having a large diameter with a gentle inclination toward the opening, and an air restriction portion that is coaxial with the opening / closing valve portion and that reduces the cross-sectional area of the compressed air supply path by a predetermined amount, and is continuous therewith. the cross-sectional area of the compressed air supply passage from zero and continuously changeable valve portion over a predetermined amount, Ri Na provided a series,
When the air pressure adjusting means and the paint adjusting means are both in a half-open state, the air restricting unit is configured to reduce the pressure so as to be a pressure suitable for the amount of paint sprayed. In the coating apparatus of the type in which the nozzle is provided on the same axis of the needle valve that slides inside the paint spray nozzle, the same effect as the invention of claim 1 can be obtained, the structure is simplified, and the number of parts is reduced. In addition, the operation timing of the paint adjustment means and the air pressure adjustment means can be adjusted and managed at the time of part processing, and the painting of the surface to be painted, especially blurry, is possible without learning advanced technology. A coating apparatus capable of facilitating painting can be provided.

According to the invention described in claim 6 , the air pressure adjusting means has a truncated cone shape in which the valve portion contacts and separates from a tapered portion formed on the inner side of the compressed air supply passage, and the air restriction portion is Since it has an annular shape with a predetermined gap between it and the inner wall of the compressed air supply passage, it is a small and simple mechanism that can be easily incorporated into the main body of the apparatus and can be manufactured at low cost. The coating apparatus which can produce the effect of the invention according to claim 5 can be provided without substantially increasing the height.
According to the seventh aspect of the present invention, the amount of paint sprayed between the needle valve and the paint spray nozzle changes continuously at least during the first half of the travel stroke of the trigger portion, and the remaining movement. At the stage, the spraying amount of paint is set to be almost the same or slightly changed, and it is suitable for blurry painting work, so you can master the advanced technology for blurry painting in the half-clutch state, which was difficult in the past. It is possible to provide a coating apparatus that can be easily performed.

DESCRIPTION OF EMBODIMENTS Hereinafter, a coating apparatus according to the present invention will be described in detail based on embodiments with reference to the drawings.
FIG. 1 is a front center longitudinal sectional view of a coating apparatus according to a first embodiment of the present invention, and FIG. 2 is an enlarged longitudinal sectional view of a portion of air pressure adjusting means incorporated in the coating apparatus of FIG. 3 is a front view showing an air valve in the air pressure adjusting means, in which (a) is a conventional air valve, (b) is an air valve according to the present invention, and FIG. FIG. 5 is an enlarged longitudinal sectional view of a tip side of a needle valve and an injection nozzle portion incorporated in the coating apparatus of FIG. 1, and FIG. 5 is an enlarged front view showing the entire needle valve of FIG. 4.
Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS. The coating apparatus of the present invention is one embodiment, and there are various forms such as combining the present invention with an automatic low-pressure spray gun body that performs remote control, or combining with a manual spray gun. In the present embodiment, the coating apparatus is described as a spray gun. Therefore, hereinafter, the coating apparatus of the present invention is referred to as a spray gun.

First, the configuration of the spray gun in the first embodiment will be described. The spray gun 1 according to the present invention is an apparatus that mixes compressed air and paint, sprays the paint with compressed air, and applies the paint onto a surface to be coated.
The spray gun 1 according to the first embodiment includes a spray gun body 4 provided with a compressed air supply passage 2 for supplying compressed air and a paint supply passage 3 for supplying paint, and the spray gun body 4. A paint spray nozzle 6 having a spray port 5 for spraying paint is provided, and a needle valve 7 that opens and closes the spray port 5 to adjust the spray amount of the paint is provided.
Further details will be described. A spray gun 1 formed in the shape of a small handgun is formed into a gripping portion 8 that grips the spray gun 1 and a barrel portion 9 that is provided continuously with the gripping portion 8 and has an injection port 5 that sprays paint and compressed air. Has been.
Further, a compressed air supply passage 2 through which compressed air passes from the lower portion of the gripping portion 8 to the injection port 5 is provided in the spray gun body 4.
And the air nipple 10 connected with the supply source of compressed air is provided in the lower part of the holding part 8. Further, a compressed air supply passage 2 is provided from the air nipple 10 to the upper side of the gripping portion 8, and is positioned substantially perpendicular to the gripping portion 8 near the boundary between the gripping portion 8 and the barrel portion 9. Air pressure adjusting means 11 for opening and closing the compressed air supply passage 2 is provided.

The air pressure adjusting means 11 is mounted in a bottomed mounting hole 12 formed so as to be orthogonal to the compressed air supply passage 2 of the spray gun body 4. The air pressure adjusting means 11 includes a valve seat body 14, a valve portion 16 that comes into contact with and separates from the valve seat portion 15 formed in a tapered shape of the valve seat body 14, and a small diameter on the small diameter end side of the valve portion 16. The air restricting portion 18 having a frame shape (or disk shape) continuously provided through the connecting portion 17, the spring receiver 19 continuously provided on the large diameter end of the valve portion 16, and one end of the spring receiver 19. The coil spring 13 is fitted and the other end is in contact with the inner end of the mounting hole 12.
The valve seat body 14 is mounted on the spray body 4 by screwing the threaded portion 20 into a female threaded portion formed on the inner periphery of the opening end of the mounting hole 12.
When the valve portion 16 having a frustum shape comes into contact with the valve seat portion 15 of the valve seat body 14, the valve seat 21 is pushed rightward in FIG. Then, the valve portion 16 is separated from the valve seat portion 15 and the compressed air supply passage 2 is opened.
An air restricting portion 18 having a large diameter is continuously provided on the small diameter end portion side of the valve portion 16 via a small-diameter connecting portion 17 and moves along the axial direction of the mounting hole 12 together with the valve portion 16. . The valve portion 16, the connecting portion 17, the air restricting portion 18, the valve stem 21, and the spring receiver 19 are integrally formed, and are always leftward in FIG. 2 by the coil spring 13, that is, the valve seat portion at the valve portion 16. 15 is biased in the direction of closing, in other words, the direction of closing the compressed air supply passage.

The middle part of the valve seat body 14, that is, the left side of the air restricting portion 18, has a plurality of circular holes so that air that passes through the valve seat portion 15 and is controlled by the air restricting portion 18 is discharged. In this case, four openings 22 are formed.
Further, an annular groove 23 is formed on the outermost periphery of the valve seat body 14, and an O-ring 24 is fitted in the annular groove 23, whereby the valve portion 16 is closed. In addition, the compressed air is prevented from leaking from the mounting hole 12 side to the downstream compressed air supply passage 2 from between the outer periphery of the valve seat body 14 and the inner wall of the spray gun body 4.
The diameter of the inner wall of the air chamber 25 of the valve seat body 14 is 6.8 mm, whereas the outer diameter D1 of the air restricting portion 18 is used to confirm the effect of the present invention.
D1A = 6.4mm
D1B = 6.5mm
D1C = 6.6mm
D1D = 6.7mm
These four types of prototypes were produced and subjected to a predetermined confirmation test. The dimensions of the other parts are as shown in FIG.

The result of this confirmation test will be described with reference to FIG.
In addition, by using an elastic member such as resin for the valve portion 16, when the valve portion 16 closes the compressed air supply passage 2, it is possible to reliably prevent the compressed air from entering and exiting.
Above the air pressure adjusting means 11 (upper stage), a needle valve 7 and a paint spray nozzle 6 for controlling the spray of paint are disposed.
The needle valve 7 has a tapered tip 26 at one end on the injection port 5 side and a coil spring 28 via a needle valve guide 27 for controlling the movement of the needle valve 7 at the other end. is doing. The coil spring 28 is biased in a direction to close the injection port 5. Further, in front of the needle valve guide 27, a needle packing 29 for sealing paint leakage is pressed by a packing adjusting screw 30. The packing adjusting screw 30 is screwed to an appropriate strength in order to prevent paint leakage and to make the needle valve 7 operate smoothly.
A paint guide path 32 provided with a paint joint 31 connected to the paint supply source is located near the center of the needle valve 7.

Further, the end portions of the needle valve guide 27 and the valve stem 21 on the injection port 5 side have a rotation center 33 in the barrel portion 9 and abut a trigger portion 34 provided substantially parallel to the grip portion 8. . Therefore, when the trigger portion 34 is pulled toward the grip portion 8, the coil spring 13 provided on the valve seat portion 15 of the air pressure adjusting means 11 and the coil spring 28 provided on the needle valve 7 are compressed.
When the coil spring 13 provided in the air pressure adjusting means 11 is compressed, the valve portion 16 provided in the air pressure adjusting means 11 moves to the coil spring 13 side, so that the compressed air supply passage 2 is opened. Then, compressed air is supplied to the injection port 5 according to the compressed air supply passage 2 provided in the barrel part 9.
At this time, the compressed air tends to flow into the air chamber 25 side of the valve seat body 14 from the gap between the valve portion 16 of the air pressure adjusting means 11 and the valve seat portion 15 of the toilet seat body 14. The flow is restricted by a gap formed between the outer peripheral edge of the disc-shaped air restricting portion 18 provided and the inner peripheral wall of the air chamber 25. As a result, even if the gap between the valve portion 16 and the valve seat portion 15 is increased, the flow rate is restricted by the air restricting portion 18, in other words, the pressure in the downstream portion of the compressed air supply passage 2, in other words, from the injection port 5 The discharged air pressure is regulated to be a predetermined pressure.

In this way, when the coil spring 28 provided at the end of the needle valve 7 is compressed, the needle valve 7 slides together with the cylindrical needle valve guide 27.
Then, since the needle valve 7 that has closed the injection port 5 is withdrawn inside the injection port 5, the injection port 5 is opened and the paint is ejected.
The valve portion 16 moves slightly faster than the needle valve 7 and is designed to inject compressed air, so that compressed air is sent slightly ahead of the paint injection. The function of adjusting the pressure of compressed air will be described in detail later.
Next, the detailed structure of the tip structure of the spray gun 1 of the first embodiment will be described. FIG. 4 is an enlarged cross-sectional view of the tip of the spray gun 1, and FIG. 5 is an enlarged front view of the needle valve 7 in the spray gun 1. For convenience of explanation, the components described with reference to FIG.
First, the tip structure of the spray gun 1 will be described with reference to FIG. In the spray gun 1, an air cap 35 is screwed into the injection port 5. The air cap 35 is provided with a plurality of small holes 37a to 37d in the vicinity of the through hole 36 provided in the center, and is further away from the center of the air cap 35. A plurality of small holes 37e to 37h drilled obliquely inward are provided. The paint is mainly ejected from the through hole 36, and compressed air is ejected from the small holes 37a to 37d provided in the periphery.

The paint is diffused by the jetted compressed air. In this way, atomization by spraying a liquid is called atomization.
The paint spray nozzle 6 is located inside the through hole 36. The paint spray nozzle 6 has a first taper portion 38 that has a smaller diameter as it goes from the spray port 5 toward the interior of the paint spray nozzle 6, and a second taper that has a larger diameter as it goes further inside from the first taper portion 38. A portion 39 and a third taper portion 40 having a larger diameter from the second taper portion 39 toward the inside are further formed.
Further, a needle valve 7 which is a rod-shaped valve as shown in FIG. The needle valve 7 includes a tip end portion 26 that is tapered, an injection amount limiting portion 41 having the same diameter continuous to the tip end portion 26, and an opening / closing valve portion 42 that is continuous therewith. The injection amount limiting portion 41 is continuous with the tip portion 26 on the inner side of the injection nozzle 6 and has the same diameter and a predetermined length with a certain play amount (1 to 2 mm) added.
The on-off valve portion 42 has a smaller taper angle than the third taper portion 40 and has a larger diameter from the injection port 5 toward the inside of the paint injection nozzle 6.

  Further, the distal end portion 26 in the first embodiment is conical, the length r of the bus bar of the distal end portion 26 forming the distal end portion 26 is 0.5 mm, and the distal end sensitivity α is 80 to 85. It is good to have a degree. In particular, when the tip angle α is 83 degrees, the coating state of the paint is greatly improved.

As shown in FIG. 1, the needle valve in the first embodiment is configured by combining a first coil spring 28a and a second coil spring 28b having different spring coefficients.
In the present embodiment, the first coil spring 28a has a lower spring coefficient than the second coil spring 28b. However, the first coil spring 28a may be a coil spring having a spring coefficient higher than that of the second coil spring 28b, or may be reversed.
The first coil spring 28 a is in contact with the needle valve guide 27, one end of the second coil spring 28 b is connected to the first coil spring 28 a, and the other end is in contact with the inner wall of the guide chamber 43. . The guide chamber 43 accommodates the proximal end side of the needle valve guide 27 and the first coil spring 28a and the second coil spring 28b.

When the trigger portion 34 is pulled with a force F from the state shown in FIG. 1, the first coil spring 28a is pushed by the needle valve guide 27 slid rearward. As the needle valve guide 27 slides, the force F is also transmitted to the second coil spring 28 b that is in contact with the inner wall of the guide chamber 43. Then, this force F is transmitted to the inner wall of the guide chamber 43, and the reaction force F ′ acts on the second coil spring 28b. Therefore, both the first coil spring 28a and the second coil spring 28b are compressed. At this time, the same force acts on the first coil spring 28a and the second coil spring 28b. However, since the elastic moduli of the two coil springs are different, in the operation up to the final stage of the trigger portion 34, The compression rate (length to be compressed) of the one coil spring 28a and the second coil spring 28b is different.
That is, the coil spring 28 in the present embodiment pulls the trigger portion 34 and mainly compresses the first coil spring 28a, and pulls the trigger portion 34 and compresses the first coil spring 28a at this stage. It is considered that the operation step is mainly performed in three stages, that is, a second stage in which the second coil spring 28b is compressed and a third stage (final stage) in which both the first coil spring 28a and the second coil spring 28b are completely compressed. be able to.

Therefore, when the first coil spring 28a is mainly compressed, only compressed air is injected, and then the second coil spring 28b is compressed halfway in addition to the first coil spring 28a. And the amount of paint is restricted, a predetermined amount is injected, and when the first coil spring 28a and the second coil spring 28b are compressed to the end, the compressed air amount and the amount of paint are maximized for injection. Can be performed.
Exactly, the operation from the initial stage to the middle stage of the trigger portion 34 can be referred to as a so-called “half-clutch state” in which fine adjustment of the needle valve 7 can be easily performed with a relatively small force. It is possible to easily perform painting that blurs the boundary between the surface and the old painted surface.
When the trigger portion 34 is pulled, the needle valve 7 slides into the needle valve guide 27 and the spray port 5 of the paint spray nozzle 6 is opened accordingly.
More specifically, by operating the trigger portion 34, as described above, the valve portion 16 of the air pressure adjusting means 11 is opened and compressed air is injected almost simultaneously with the compression of the first coil spring 28a. The At that time, the needle valve 7 slides into the paint spray nozzle 6.

As a result, the state in which both the taper portion of the on-off valve portion 42 of the needle valve 7 and the second taper portion 39 of the paint spray nozzle 6 have been properly fitted is shifted so that there is a slight gap between the two tapers. Clearance occurs. At this time, the injection amount restriction part 41 of the needle valve 7 is located in the first taper part 38 of the paint injection nozzle 6.
At this time, when the needle valve 7 and the first coil spring 28a are in the first state described above, the compressed air starts to be injected from the injection port 5.
When the trigger portion 34 is further operated and the second coil spring 28 b starts to be compressed, the needle valve 7 further slides into the needle valve guide 27 inside the paint spray nozzle 6. Then, the clearance between the injection amount limiting part 41 and the second taper part 39 is further increased. In this state, an appropriate amount of paint and compressed air are injected from the injection port 5.
In addition, when the first coil spring 28a and the second coil spring 28b are completely compressed, the tip end portion 26 of the needle is completely accommodated inside the paint spray nozzle 6.
At this time, a maximum amount of both compressed air and paint is ejected from the ejection port 5.

Next, the spraying principle of the spray gun 1 in the first embodiment described above will be described together with an explanation of the operation.
First, when performing blur coating using the spray gun 1 according to the first embodiment, the operator holds the holding portion 8 with the injection port 5 facing the surface to be coated. At this time, the injection port 5 is located at the boundary between the old painted surface (center portion) and the surface to be painted. When the trigger portion 34 is pulled toward the gripping portion 8 against the biasing force of the coil springs 13 and 28, the trigger portion 34 first comes into contact with the valve rod 21 of the air pressure adjusting means 11, and a slight delay thereof. Is brought into contact with the needle valve guide 27.
First, when the valve rod 21 of the air pressure adjusting means 11 comes into contact with the trigger portion 34, the valve portion 16 is internally passed through the valve rod 21 → the air restricting portion 18 → the connecting portion 17 in order (in FIG. 2). Move to the right). Then, the contact state between the valve portion 16 and the valve seat portion 15 is released, and the compressed air sent from below in the drawing flows out to the air chamber 25 side through a gap formed between them. At this time, since the space between the inner peripheral wall of the air chamber 25 and the outer peripheral surface of the air restricting portion 18 is restricted, the pressure sent from the air compressor and introduced into the compressed air supply passage 2 of the spray gun 1 is The pressure is reduced by a predetermined amount and sent to the compressed air supply passage 2 downstream through the opening 22.

The compressed air is stably supplied with a limited pressure immediately after the valve portion 16 is opened (half-clutch state).
On the other hand, when the needle valve guide 27 comes into contact with the trigger portion 34, the needle valve 7 slides and enters the inside.
That is, the needle valve 7 that has closed the injection port 5 is pulled back into the barrel portion 9.
Along with this, the closed injection port 5 is opened.
Further, the paint in the paint guide path 32 is ejected from the ejection port 5. At this time, as described above, since the decompressed compressed air is injected slightly earlier, the paint is atomized with an appropriate amount of compressed air from the beginning.
Moreover, due to the action of the air restricting portion 18 of the air pressure adjusting means 11 of the present embodiment, the pressure is reduced from immediately after the opening operation of the valve portion 16 to a pressure suitable for blur coating, and the pressure is gradually increased according to the pulling operation of the trigger portion 34. This can improve the balance with the coating material supply by the coating material adjusting means.

  That is, in the paint injection nozzle 6 and the needle valve 7, the second taper portion of the paint injection nozzle 5 and the injection amount restriction portion 41 of the needle valve 7 are not the same inclined surface (taper surface), but the injection amount restriction portion. Since the outer diameter of 41 is the same, even if the needle valve 7 is pulled into the paint injection nozzle 6, the gap between the second taper portion 39 and the injection amount limiting portion 41 is substantially constant.

Therefore, the compressed air supplied from the small holes 37 a, 37 b, 37 c, 37 d and the small holes 37 e, 37 f, 37 g, 37 h provided in the air cap 35 is flown by the injection amount restriction unit 41. It is possible to squirt the amount of paint commensurate with
Then, unlike the conventional case, the paint is not completely atomized immediately after the injection, and there is no possibility that the particles are injected as large particles.
In particular, in Patent Document 1, although the points of the needle valve 7 and the paint injection nozzle 6 are improved, no consideration is given to the compressed air adjusting means. Therefore, if the painter pulls the trigger portion 34 shallowly, so-called half-clutch state, an attempt is made to blur and paint, even if the injection amount can be finely controlled between the needle valve 7 taper portion and the paint injection nozzle. The air pressure adjusting means cannot be adjusted by the trigger part, that is, a large compressed air is discharged as soon as the trigger part is pulled, and conversely, if it is attempted to squeeze this, the trigger part is pulled apart. In addition, since the amount of compressed air suddenly approaches zero, the balance between the amount of air and the amount of injection cannot be achieved, and the present invention can properly balance the amount of air and the amount of spray of paint. .

Next, the coating apparatus which concerns on the 2nd Embodiment of this invention is demonstrated below with reference to FIG. 8, FIG.
The major difference between the first embodiment described above and the second embodiment to be described below is that the spray gun 1 of the first embodiment has an air pressure adjusting means 11 and a paint adjusting means which are vertically Whereas the spray gun 51 of the second embodiment is arranged at the position of the step, the air pressure adjusting means 61 is on the same axis as the paint adjusting means, and opens and closes the needle valve 58 and the compressed air supply passage. Alternatively, the adjusting means is configured integrally.
FIG. 8 is a front center longitudinal cross-sectional view of a coating apparatus according to a second embodiment of the present invention, and FIG. 9 is a cross-sectional view of air pressure adjusting means incorporated in the coating apparatus of FIG. 10 is a front view showing the configuration of a valve portion for adjusting the air pressure, among which FIG. 10 (a) shows a conventional valve portion, and FIG. 10 (b) shows the air pressure adjusting means of FIG. It is a front view which shows the part of the valve | bulb part and air restriction | limiting part which are built in.
The spray gun 51 in the second embodiment is provided in a spray gun body 54 provided with a compressed air supply passage 52 for supplying compressed air and a paint supply passage 53 for supplying paint, and the spray gun main body 54. Further, a paint spray nozzle 56 having a spray port 55 for spraying paint is provided, and a needle valve 57 that opens and closes the spray port 55 to adjust the spray amount of the paint.

Further details will be described. The spray gun 51 formed in the shape of a small handgun is formed into a grip part 58 that grips the spray gun 51 and a barrel part 59 that is provided continuously with the grip part 58 and has an injection port 55 that sprays paint and compressed air. Has been.
Further, a compressed air supply passage 52 through which compressed air passes from the lower part of the grip portion 58 to the injection port 55 is provided in the spray gun body 54.
An air nipple 60 connected to a compressed air supply source is provided below the grip portion 58. Further, a compressed air supply passage 52 is provided from the air nipple 60 toward the upper side of the grip portion 58, and is positioned substantially perpendicular to the grip portion 58 near the boundary between the grip portion 58 and the barrel portion 59. Air pressure adjusting means 61 for opening and closing the compressed air supply passage 52 is provided.
The air pressure adjusting means 61 is mounted in a mounting hole 62 formed so as to be orthogonal to the compressed air supply passage 52 of the spray gun body 54. The air pressure adjusting means 61 is connected to a valve seat body 64, a valve portion 66 that comes into contact with and separates from a valve seat portion 65 formed in a tapered shape of the valve seat body 64, and a small diameter end side of the valve portion 66. The air restricting portion 68 having a coma shape (or a cylindrical shape), a collar portion 67 connected to the large-diameter end of the valve portion 66, one end fitted into the collar portion 67, and the other end being a cap member 94, a coil spring 78 that is in contact with the inner end of the needle 94, a needle valve stopper 95 that is screwed into the cap member 94 and can arbitrarily set the retracted position of the needle valve, and is energized inside the needle valve stopper 95. The coil spring 63 is made up of.

The valve seat body 64 is mounted on the spray body 54 by screwing the threaded portion 70 into the female threaded portion formed on the inner periphery of the opening end of the mounting hole 62.
The valve seat 65 of the valve seat body 64 has a valve action to stop the flow of air when a valve portion 66 having a substantially frustum shape comes into contact with the valve seat body 64. In FIG. When pushed, the valve portion 66 is separated from the valve seat portion 65 to open the compressed air supply passage 52.
An air restricting portion 68 having a slight gap between the valve portion 66 and the inner peripheral wall of the air chamber 75 is connected to the small diameter end portion side of the valve portion 66, and the axial direction of the inner space of the valve seat body 64 together with the valve portion 66. Move along.
The air pressure adjusting means 61 includes a valve seat body 64 having a through hole, a valve body including a valve portion 66, an air restricting portion 68, and a collar portion 67, and a part of a needle valve 57 constituting a part of the paint adjusting means. The cap member 94 screwed into the female screw of the valve seat body 64, the needle valve stopper 95 screwed into the female screw of the cap member 94, and the valve portion 66 and the bottom of the cap member 94 in the valve seat main body 64. And a coil spring 63 accommodated in a compressed state.

The needle valve 57 is freely slidable with respect to the valve main body and the cap member 94 including the valve portion 66 and the air restricting portion 68. However, the needle valve 57 is retracted by changing the tightening position of the needle valve stopper 95, that is, the paint. The amount of injection can be changed.
The valve body portion is configured to constantly press the valve portion 66 against the valve seat portion 65 by a coil spring 78 and close the pressurized air supply passage 52.
Further, the needle valve 57 is always pressed to the left in FIG. 9 by the coil spring 63 and is urged in a direction to close the injection port 55.
In addition, by using an elastic member such as resin for the valve portion 66, when the valve portion 66 closes the compressed air supply passage 52, it is possible to reliably prevent the compressed air from entering and exiting.
A needle valve 57 and a paint spray nozzle 56 for controlling the spraying of paint are disposed on the left coaxial side of the air pressure adjusting means 61.

The needle valve 57 has a tapered tip 76 at one end on the injection port 55 side, and a coil spring abutted with a needle valve stopper 95 that controls the movement of the needle valve 57 at the other end. 63. The coil spring 63 biases the injection port 55 in the closing direction. Further, a needle packing 79 for sealing paint leakage is pressed by a packing adjusting screw 80 at an intermediate portion of the needle valve 57. The packing adjusting screw 80 is screwed to an appropriate strength so as to prevent paint leakage and the needle valve 57 operates smoothly.
Further, a paint guide path 82 provided with a paint joint 81 connected to the paint supply source is located slightly forward of the center of the needle valve 57.
Further, the end portion of the needle valve guide 77 on the injection port 55 side has a rotation center 83 in the barrel portion 59 and is in contact with a trigger portion 84 provided substantially parallel to the grip portion 58. Therefore, when the trigger portion 84 is pulled toward the grip portion 58, first, a coil spring 78 provided on the valve portion 66 of the air pressure adjusting means 61 and a coil spring 63 applied to the engagement portion 73 of the needle valve 57 are formed. Both are compressed.

When the coil spring 78 provided in the air pressure adjusting means 61 is compressed, the valve portion 66 provided in the air pressure adjusting means 61 moves to the coil spring 78 side, so that the valve portion 66 is separated from the valve seat portion 65. Then, the compressed air supply passage 52 is opened. Then, compressed air is supplied from the opening 72 to the injection port 55 according to the compressed air supply passage 52 provided in the barrel portion 59.
That is, the compressed air tries to flow into the air chamber 75 side of the valve seat body 64 from the gap between the valve portion 66 of the air pressure adjusting means 61 and the valve seat portion 65 of the valve seat body 64, but continues to the valve portion 66. The flow is restricted by a gap formed between the outer peripheral surface of the cylindrical (or coma) air restricting portion 68 provided and the inner peripheral wall of the air chamber 75. As a result, even if the gap between the valve portion 66 and the valve seat portion 65 becomes large, the flow rate discharged from the opening 72 is restricted by the air restriction portion 68, and the pressure in the downstream portion of the compressed air supply passage 52, In other words, the air pressure discharged from the injection port 55 is restricted to a predetermined pressure.

  Thus, in parallel with the movement of the valve portion 66 opening the valve seat portion 65, the tip (right side) of the collar portion 67 connected to the valve portion 66 moves the engagement portion 73 integral with the needle valve 57 to the right. Push towards.

Thus, when the coil spring 63 provided at the end of the engaging portion 73 of the needle valve 57 is compressed, the needle valve 57 slides to the right together with the cylindrical needle valve guide 77, and the paint injection nozzle 56.
Then, since the needle valve 57 that has closed the injection port 55 is retracted into the injection port 55, the injection port 55 is opened and the paint is ejected.
The valve portion 66 moves slightly faster than the needle valve 57 and is designed to inject compressed air, so that compressed air is sent slightly before the paint injection. The balance with the injection amount of the paint discharged late is achieved by the function of adjusting the pressure of the compressed air.
Next, the tip structure of the spray gun 51 according to the second embodiment will be described, but since it is almost in common with the first embodiment, the description will be omitted.
First, the tip structure of the spray gun 51 will be described with reference to FIG. The spray gun 51 has an air cap 85 screwed into the injection port 55. As shown in detail in FIG. 4, the air cap 85 is provided with a plurality of small holes around a through hole 86 provided in the center. The paint is mainly ejected from the through-hole 86, and compressed air is ejected from a small hole provided in the periphery.

Then, the paint is diffused by the jetted compressed air.
A paint spray nozzle 56 is located inside the through hole 86. The paint spray nozzle 56 has a first taper portion that has a smaller diameter as it goes from the spray port 55 to the interior of the paint spray nozzle 56, and a second taper portion that has a larger diameter as it goes further inside from the first taper portion. The third taper portion has a diameter that increases further from the second taper portion toward the inside.
Further, a needle valve 57, which is a rod-shaped valve as shown in FIG. The needle valve 57 includes a tip portion 76 that is tapered, an injection amount restriction portion 91, and an on-off valve portion 92. The spray amount limiting portion 91 is continuous with the tip portion 76 on the inner side of the paint spray nozzle 56, and has a predetermined length and the same diameter with a certain play amount (1 to 2 mm) added.
The on-off valve portion 92 has a taper angle smaller than that of the third taper portion, and is formed to have a larger diameter from the injection port 55 toward the inside of the paint injection nozzle 56.

Further, the tip 76 in the second embodiment is conical, the length r of the bus bar of the tip 76 forming the tip 76 is 0.5 mm, and the tip angle α is 80 to 85. It is good to have a degree. In particular, when the tip angle α is 83 degrees, the coating state of the paint is greatly improved.
In the second embodiment, the coil spring 78 has a lower spring coefficient than the coil spring 63. However, the coil spring 78 may be a coil spring having a higher spring coefficient than that of the coil spring 63, and may of course be reversed or may be the same.
The coil spring 78 is housed between the valve portion 66 and the cap member 94, and the coil spring 63 is housed in a compressed state between the engagement portion 73 and the needle valve stopper 95.
Then, when the trigger portion 84 is pulled with a force F from the state of FIG. 2, the coil spring 78 is pushed by the needle valve guide 77 and the valve seat body 64 slid rearward. Further, the coil spring 63 is pushed by the engaging portion 73 sequentially through the collar portion 67 of the valve seat body 64 as the needle valve guide 77 and the valve seat body 64 slide.

Then, this force F is transmitted to the cap member 94 and the inner wall of the needle valve stopper 95, and the reaction force F ′ acts on the coil springs 78 and 63. Therefore, both the coil spring 78 and the coil spring 63 are compressed. At this time, the same force is applied to the coil spring 78 and the coil spring 63, but the elastic moduli of the two coil springs are different. The compression rate (length to be compressed) of the spring 63 is different.
When the trigger portion 84 is pulled, the needle valve 57 is slid inward by the needle valve guide 77 and the spray port 55 of the paint spray nozzle 56 is opened.
More specifically, by operating the trigger portion 84, the valve portion 66 of the air pressure adjusting means 61 opens the valve seat portion 65 and the compressed air is injected at the same time as described above. The coil spring 63 is compressed. At that time, the needle valve 57 slides into the paint spray nozzle 56.
As a result, the state in which both the taper portion of the on-off valve portion 92 of the needle valve 57 and the second taper portion of the paint spray nozzle 56 have been fitted properly is shifted so that a slight gap is present between the two tapers. Clearance occurs. Thus, the injection amount restriction part 91 of the needle valve 57 is located in the first taper part of the paint injection nozzle 56. In the first state, compressed air starts to be injected from the injection port 55.

When the trigger portion 84 is further operated and the coil spring 63 starts to be compressed, the needle valve 57 further slides inward into the paint spray nozzle 56. Then, the clearance between the injection amount limiting part 91 and the second taper part is further increased. In this state, an appropriate amount of paint and compressed air are ejected from the ejection port 55.
In addition, when the coil spring 78 and the coil spring 63 are completely compressed, the tip 76 of the needle is completely accommodated inside the paint spray nozzle 56.
At this time, the compressed air is set to the maximum air amount and the paint is injected from the injection port 55 to the maximum amount.
Next, the spraying principle of the spray gun 51 in the second embodiment described above will be described along with the operation description.
First, when performing blur coating using the spray gun 51 in the second embodiment, the operator holds the holding portion 58 with the spray port 55 facing the surface to be coated. At this time, the injection port 55 is located at the boundary between the old painted surface (center portion) and the surface to be painted. When the trigger portion 84 is pulled toward the grip portion 58 against the biasing force of the coil springs 78 and 63, the trigger portion 84 first comes into contact with the needle valve guide 77. The needle valve guide 77 is in contact with the air restricting portion 68.

First, when the air restricting portion 68 of the air pressure adjusting means 61 is pushed into the trigger portion 84 via the needle valve guide 77, the valve portion 66 is internally provided via the air restricting portion 68 (in FIG. 8). Move to the right). Then, the contact state between the valve portion 66 and the valve seat portion 65 is released, and the compressed air sent from below in the drawing through the gap formed between the two is from the opening opened in the valve seat body 64. Enters, passes through the gap between the valve portion 66 and the valve seat portion 65 and flows out to the air chamber 75 side. At this time, since the space between the inner peripheral wall of the air chamber 75 and the outer peripheral surface of the air restricting portion 68 is regulated, the pressure sent from the air compressor and introduced into the compressed air supply passage 52 of the spray gun 51 is The pressure is reduced by a predetermined amount, and the compressed air is supplied to the downstream compressed air supply passage 52 through the opening 72.
For this reason, the limited pressure is stably supplied to the compressed air immediately after the valve portion 66 is opened (half clutch state).
On the other hand, when the needle valve guide 77 is pushed by the trigger portion 84, the needle valve guide 77 → the valve main body portion (the air restricting portion 68, the valve portion 66, the collar portion 67) → the engagement portion 73 is sequentially passed through the needle. Valve 57 slides to the right.

That is, the needle valve 57 that has closed the injection port 55 is pulled back into the barrel portion 59.
Accordingly, the closed injection port 55 is opened.
Further, the paint in the paint guide path 82 is ejected from the ejection port 55. At this time, as described above, since the decompressed compressed air is injected slightly earlier, the paint is atomized with an appropriate amount of compressed air from the beginning.
Moreover, due to the action of the air restricting portion 68 of the air pressure adjusting means 61 of the second embodiment, the pressure is reduced from immediately after the opening operation of the valve portion 66 to a pressure suitable for blurring coating, and gradually according to the pulling operation of the trigger portion 84. Since the pressure can be increased, the balance with the coating material supply by the coating material adjusting means is improved.
That is, the second tapered portion of the paint spray nozzle 56 and the injection amount limiting portion 91 of the needle valve 57 are not the same inclined surface (tapered surface), but the outer diameter of the injection amount limiting portion 91 is the same diameter. Therefore, even when the needle valve 57 is pulled into the paint spray nozzle 56, the gap between the second tapered portion and the spray amount limiting portion 91 is substantially constant.
Therefore, the compressed air supplied from the small holes provided in the air cap 85 can eject the paint corresponding to the flow rate of the compressed air by the injection amount limiting unit 91.

Then, unlike the conventional case, the paint is not completely atomized immediately after the injection, and there is no possibility that the particles are injected as large particles.
In particular, in Patent Document 1, although the points of the needle valve 57 and the paint injection nozzle 56 are improved, no consideration is given to the compressed air adjusting means. Therefore, if the painter pulls the trigger portion 84 shallowly, so-called half-clutch, it is possible to finely control the injection amount between the tapered portion of the needle valve 57 and the paint injection nozzle. However, the air pressure adjusting means cannot be adjusted by the trigger portion 84, that is, as soon as the trigger portion 84 is pulled, a large amount of compressed air is discharged, and conversely, if it is operated to squeeze it, the trigger portion is pulled apart. Since the amount of compressed air suddenly approaches zero, the balance between the amount of air and the amount of spray could not be achieved, but the present invention can properly balance the amount of air and the amount of spray of paint. It is a thing.

Example 1
Based on the first embodiment shown in FIG. 3B, the valve rod 21, the air restricting portion 18, the connecting portion 17, the valve portion 16, and the spring receiver 19 constituting the valve main body portion of the air adjusting means 11 are shown. The Example formed in the specific dimension in drawing is shown. Moreover, the dimension of the inner wall (part shown with a dashed-two dotted line) of the air chamber 25 of the valve seat main body 14 was set to 6.8 mm.
In FIG. 3B, the symbol D1 is the dimension of the diameter of the air restricting portion 18. In the first embodiment, this is set to 6.7 mm, and in the second embodiment, It was set to 6.6 mm.
FIG. 5 specifically shows the specific dimensions of the injection amount limiting portion 41 of the needle valve 7, that is, the length L and the outer diameter D2. Among these dimensions, in the first embodiment, the outer diameter D2 is set to 1.1 mm and the length L is set to 2.5 mm. In the second embodiment, the outer diameter D2 is set to 1.1 mm, The length L was set to 2.0 mm.

The inventor conducted a confirmation test on the first and second embodiments having the above-described configuration and the conventional air spray gun (manufactured by Keihiro Seisakusho, GR-310). The data of the test results are shown in Tables 1 to 4, and the graphed results are shown in FIGS. 6 (a) to 6 (d), respectively.
In each figure, the series 1 is the pressure (original pressure) value of the air transformer, and the series 2 is the local pressure value of the air spray gun supplied from the air transformer via an air hose having an inner diameter of 6 mm and a length of 10 m. Series 3 is a pressure value in a so-called half-clutch state where the trigger portion 34 is pulled to the middle, and Series 4 is a pressure value when the valve portion 16 is fully opened, the trigger portion 34 being pulled to the maximum. Each unit is Mpa.
In addition, the needle valve opening condition in this verification test, that is, the rotation speed from the fully closed state of the needle valve adjustment knob 71 is 3 rotations in FIG. 6A, 3 rotations in FIG. In c), two rotations are set, and in (d), one rotation is set.

  Under such conditions, the results of verifying the relationship between the amount of opening of the valve portion and the pressure in the air pressure adjusting means 11 are shown in Tables 1 to 4 below, and a graph of Tables 1 to 4 is shown below. 6 (a) to (d), respectively.

Among the graphs of Tables 1 to 4 and FIGS. 6A to 6D, first, as shown in Table 3 and FIG. 6C, the conventional air spray gun (needle adjustment knob 71 is set to 2). In the case of rotation), when the pressure of the transformer (series 1) is 0.35 Mpa, the pressure decreases to 0.22 Mpa in the half-clutch state (series 3), and in the fully open state of the valve section (series 4). It is reduced to about 0.18 and about half.
On the contrary, in the air spray gun according to the first embodiment of the present invention, as shown in Table 1 and FIG. 6 (a), when the transformer pressure (series 1) is 0.35 Mp, In series 3), it becomes 0.3 Mpa, and in the fully open state of the valve section (series 4), it remains at 0.25, and there is only 0.1 Mpa opening with respect to the pressure of the transformer, and there is a difference between the half clutch and the valve section fully opened. It can be seen that the transition is smoothly decreasing at 0.05.
On the other hand, as shown in Table 3 and FIG. 6 (c), in the conventional air spray gun, when the half-clutch state is reduced from the pressure of the transformer, the pressure drops by 0.13 Mpa, and when the half-clutch state is fully opened, .04 Mpa.
For this reason, in the conventional air spray gun, the width of the half-clutch state of the trigger portion is narrow, and in the process of releasing the trigger portion, it has been shown that the air pressure suddenly decreases, in other words, It is nothing but telling the difficulty of maintaining a half-clutch state. Such a tendency is the same as seen in Table 4 and FIG.
Conversely, as can be seen in Table 1 and FIG. 6 (a) and Table 2 and FIG. 6 (b), according to the air spray guns of the first and second embodiments, in the so-called half-clutch state. It is very easy to change the air pressure over a wide range.
In addition, about the outer diameter D1 of the air restriction part 18 mentioned above, it examines about the range of 6.4 mm-6.7 mm, and about 1.1 mm-about the outer diameter D2 of the injection amount restriction | limiting part 41 of the needle valve 7. Verification is made for a range of 1.2 mm, and the length L of the ejection amount limiting portion 41 of the needle valve 7 is verified for a range of 2 mm to 2.5 mm. The same effects as those of the first and second embodiments are obtained. was gotten.
Next, in the first embodiment, the second embodiment, and the conventional spray gun of the present invention, the state of the paint ejection amount in the so-called half-clutch state, the state of the paint ejection amount when the needle valve is fully opened, and The state of the conventional paint spray amount was confirmed.
That is, in Table 5 and FIG. 7, the condition 1 is when the air valve portion is fully opened in the first embodiment, and the condition 2 is when the air valve portion is half-clutch in the first embodiment. Condition 3 is when the air valve portion is fully opened with a conventional spray gun, Condition 4 is when the air valve portion is fully opened in the second embodiment, and Condition 5 is that in the second embodiment. When the air valve portion is a half-clutch, these are respectively shown.
The needle valve adjustment knob rotation speed is the rotation speed from the closed state. For example, 0.75 means that the ¼ rotation has been performed from the fully closed state.
The numerical value described in the column of each condition represents the time (seconds) until all 70 g of paint is sprayed.
Further, verification was performed in a state where compressed air of 3 Mpa outputted from the transformer was supplied with compressed air having a pressure of 2.8 Mpa through an air hose having an inner diameter of 6 mm and a length of 10 m.
Further, in the first embodiment, as described above, the outer diameter D1 of the air restricting portion 18 is 6.7 mm, the outer diameter D2 of the injection amount restricting portion 41 is 1.1 mm, and the length is 2. .5 mm.
Further, in the second embodiment, the outer diameter D1 of the air restricting portion 18 is 6.6 mm, the diameter of the injection amount restricting portion 41 is 1.1 mm, and the length L is 2.0 mm.
The verification results obtained under these conditions are shown in FIG.

In Table 5, in the conventional spray gun (condition 3), it took 115 seconds to spray 70 g of paint (solvent) when the needle valve adjustment knob was rotated 3/4 (0.75). It is 51 seconds when it is opened for 5 turns, 39 seconds when it is opened for 2 turns, and the amount of paint spraying increases rapidly here.
In other words, the conventional air spray gun has a characteristic that the amount of paint spray is small at first and increases suddenly when a certain point is exceeded, and from a different perspective, the spray amount is reduced from the fully open state to the half open state. The amount of eruption will suddenly decrease.
On the other hand, according to the first embodiment and the second embodiment of the present invention, when the condition 1 and the condition 4 (the air valve portion is fully opened) are seen, the one-turn needle valve is opened from 3/4 rotation. It can be seen from Table 5 and FIG. 7 that the amount of ejection suddenly increases until then, but then gradually decreases until 1.5, 2, 3 and 3.5 rotations. .

From Table 5 (Condition 3) and FIG. 7 (Condition 3), the conventional spray gun has too much disparity in the amount of paint sprayed, and the interval over which the spray amount can be adjusted is too short, making it difficult to operate the half clutch. Is clearly appearing in the data.
For this reason, in the conventional air spray gun, when coating is performed from the center to the blurred portion, the coating film thickness is inclined abruptly.
One of the techniques of blurring is to apply it so as to draw a gradation well.
In order to realize such a coating film form, as shown in FIG. 7, it is necessary to perform the blur operation so that the spray amount of the paint smoothly changes to the full opening according to the degree of opening the needle valve adjustment knob. It will be easy.
In the first and second embodiments described above, FIG. 7 shows that the paint is ejected in a smooth shape from one rotation of the needle valve adjustment knob to full opening, and in this state, This means that half-clutch operation is facilitated.

Further, in the case of Condition 2 and Condition 5 in Table 5 and FIG. 7, that is, the transition of the paint ejection amount in the half-clutch state, the paint ejection amount in the case of Condition 1 and Condition 4, that is, the fully open state is further increased. It can be understood that the transition of is smooth.
In other words, this is an important factor for the dryness of the central portion and the blurred portion in the blurred coating.
In general, when blur coating is performed with an air spray gun, the center portion and the blur portion are performed in a continuous gun operation flow, which is an unavoidable operation.
While performing such a continuous gun operation, it is necessary to make the drying properties of the coating film at the center part and the blur part the same condition.

In order to solve this problem, the present inventor creates a difference between the air pressure in the half-clutch state in the blur part and the air pressure in the center part, and lowers the air pressure in the blur part from the center part, thereby reducing the drying property of the coating film. Inspired to be late.
However, in the case of blurring, it is necessary to make the coating film thin and smooth, and when the coating film is applied under the same conditions (air pressure) in the same state, the drying property becomes faster. With a spray gun, it is impossible to produce (reproduce) the work under the same conditions.
On the other hand, in the present invention, the function of continuously reducing the air pressure in the same flow through the spray gun operation so as to satisfy the above condition, that is, the function of continuously reducing the air pressure in the half-clutch state Was created.
This is because the spray gun of the present invention has a function of an air restricting portion (that is, an air regulator valve) that reduces the cross-sectional area of the compressed air supply passage by a predetermined amount as a function in the spray gun body. .

10 (a) and 10 (b) are front views showing the external configuration of the valve body, in which (a) is a conventional valve body, and (b) shows the shape of the third embodiment of the present invention. Show.
The conventional valve main body is composed of only the valve portion 66 'and the collar portion 67'. In the third embodiment, the valve body is composed of the collar portion 67, the valve portion 66, the air restricting portion 68, and the escape portion 68a. .
In particular, in the third embodiment, the inner diameter of the portion of the valve seat body 64 into which the air restricting portion 68 is fitted is set to 8 mm, and the outer diameter D2 of the air restricting portion 68 is 7.5 mm, 7.6 mm, 7 When five prototypes of 7 mm, 7.8 mm, and 7.9 mm were prototyped and tested for confirmation, the air pressure in the half-clutch was limited, and it was confirmed that they matched well with the amount of paint sprayed. did it.
According to the third embodiment, it is possible to add the function of the air regulator only by attaching at least the air restricting portion of the valve main body, and the cost hardly increases. Can be produced.

It is a front center longitudinal cross-sectional view of the coating device which concerns on the 1st Embodiment of this invention. FIG. 2 is an enlarged longitudinal sectional view of a part of air pressure adjusting means incorporated in the painting apparatus of FIG. 1. It is a front view which shows the air valve in an air pressure adjustment means, among these, (a) is a conventional air valve, (b) is a front view which respectively shows the external appearance structure of the air valve which concerns on this invention. FIG. 2 is an enlarged vertical cross-sectional view of a tip side of a needle valve and an injection nozzle portion incorporated in the coating apparatus of FIG. 1. It is a front view which expands and shows the whole needle valve of FIG. FIG. 6 shows the pressure state of the valve portion in the first and second embodiments and the conventional spray gun. Of these, FIG. 6A shows the first embodiment, and FIG. 6B shows the second embodiment. Examples (c) and (d) are characteristic diagrams of different conventional spray guns. It is a paint injection amount comparison characteristic view of the 1st example of the present invention, the 2nd example, and the conventional spray gun. It is a front center longitudinal cross-sectional view which shows the structure of the coating device which concerns on the 2nd Example of this invention. It is sectional drawing which shows the structure of parts, such as a valve seat main body, a valve part, a needle valve, etc. which were integrated in the coating apparatus of FIG. It is a front view which shows the structure of the valve part of the 3rd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Spray gun 2 Compressed air supply path 3 Paint supply path 4 Spray gun main body 5 Injection port 5 Paint injection nozzle 6 Paint injection nozzle 7 Needle valve 8 Grip part 9 Gun barrel part 10 Air nipple 11 Air pressure adjustment means 12 Mounting hole 13 Coil spring 14 Valve seat body 15 Valve seat part 16 Valve part
1 7 connecting portion 18 air restricting portion 19 spring receiver 20 screw portion 21 valve rod 22 opening portion 23 annular groove 24 O-ring 25 air chamber 26 tip portion 27 needle valve guide 28 coil spring 28a first coil spring 28b second coil spring 29 Needle packing 30 Packing adjustment screw 31 Paint joint 32 Paint guide path 33 Center of rotation 34 Trigger part 35 Air cap 36 Through hole 37a, 37b, 37c, 37d Small hole 37e, 37f, 37g, 37h Small hole 38 First taper part 39 First Two taper portion 40 Third taper portion 41 Injection amount limiting portion 42 Opening / closing valve portion 43 Guide chamber 51 Spray gun 52 Compressed air supply passage 53 Paint supply passage 54 Spray gun body 55 Injection port 55 Paint injection nozzle 56 Paint injection nozzle 57 Needle valve 58 Needle valve 58 Grip 59 barrel portion 60 air nipple 61 air pressure adjusting means 62 mounting hole 63 coil spring 64 valve seat body 65 valve seat portion 66 valve portion 67 collar portion 68 air restricting portion 68a escape portion 70 screw portion 71 needle valve adjusting knob 72 opening portion 73 engagement Joint part 75 Air chamber 76 Tip part 77 Needle valve guide 78 Coil spring 79 Needle packing 80 Packing adjustment screw 81 Paint joint 82 Paint guideway 83 Rotation center 84 Trigger part 85 Air cap 86 Through hole 91 Injection amount restriction part 92 Opening / closing valve part 94 Cap member 95 Needle valve stopper

Claims (7)

A coating device that mixes compressed air and paint, atomizes the paint and applies it to the surface to be coated,
The coating apparatus comprises a coating apparatus body provided with a compressed air supply passage for supplying compressed air and a paint supply passage for supplying paint;
A paint spray nozzle provided on the main body of the coating apparatus and having a spray nozzle for spraying paint;
Air pressure adjusting means for opening and closing the compressed air supply passage and adjusting the compressed air pressure;
A paint adjusting means for opening and closing the injection port and adjusting the spray amount of the paint;
With
The air pressure adjusting means is provided integrally with a valve portion capable of continuously changing a cross-sectional area of the compressed air supply passage from zero to a predetermined amount, and a cross-sectional area of the compressed air supply passage provided downstream of the valve portion. An air restricting section that reduces the pressure by a predetermined amount and configured to operate the paint adjusting means and the air adjusting means in conjunction with each other ,
A coating apparatus, wherein when the air pressure adjusting means and the paint adjusting means are both in a half-open state, the air restricting portion is configured to reduce the pressure so as to be a pressure suitable for the amount of paint ejected . The air pressure adjusting means has a truncated cone shape in which the valve portion contacts and separates from a tapered portion formed on the inner side of the compressed air supply passage, and the air restriction portion has a disk shape. The coating apparatus according to claim 1. The paint adjusting means is a needle valve that is slidable inside the paint injection nozzle, and the needle valve has a tapered tip positioned on the injection port side, and the inside of the paint injection nozzle on the inside of the paint injection nozzle. An injection amount limiting portion having a predetermined length and the same diameter that is continuous with the tip portion and having a certain play amount, and further, the diameter increases continuously with the injection amount limiting portion toward the inside of the nozzle. The coating apparatus according to claim 1 or 2, comprising an on-off valve portion and a shaft portion that is continuous with the on-off valve portion and restricts sliding in an axial direction. The air pressure adjusting means and the paint adjusting means are each urged by an elastic member in a direction to close the compressed air supply passage and the injection port, and the trigger portion is pulled against the urging force of the elastic member. The coating apparatus according to claim 1, wherein the coating apparatus is moved in an opening direction in accordance with the moving operation. A coating device that mixes compressed air and paint, atomizes the paint and applies it to the surface to be coated,
The coating apparatus comprises a coating apparatus body provided with a compressed air supply passage for supplying compressed air and a paint supply passage for supplying paint;
A paint spray nozzle provided on the main body of the coating apparatus and having a spray nozzle for spraying paint;
Air pressure adjusting means for opening and closing the compressed air supply passage and adjusting the compressed air pressure;
A paint adjusting means for opening and closing the injection port and adjusting the spray amount of the paint;
With
The paint adjusting means and the air pressure adjusting means are respectively provided on the same axis of a needle valve that is slidable inside the paint injection nozzle,
The needle valve has a tapered tip positioned on the injection port side,
An inside of the paint spray nozzle, having a predetermined length that is continuous with the tip and adding a certain play amount and having the same diameter, and is further continuous with the spray amount limiter and inside the nozzle An opening / closing valve portion having a large diameter with a gentle inclination toward the opening, and an air restriction portion that is coaxial with the opening / closing valve portion and that reduces the cross-sectional area of the compressed air supply path by a predetermined amount, and is continuous therewith. the cross-sectional area of the compressed air supply passage from zero and continuously changeable valve portion over a predetermined amount, Ri Na provided a series,
A coating apparatus, wherein when the air pressure adjusting means and the paint adjusting means are both in a half-open state, the air restricting portion is configured to reduce the pressure so as to be a pressure suitable for the amount of paint ejected . The air pressure adjusting means has a truncated cone shape in which the valve portion is in contact with and separated from a tapered portion formed on the inner side of the compressed air supply passage, and the air restriction portion is between the inner wall of the compressed air supply passage. The coating apparatus according to claim 5 , wherein the coating apparatus has an annular shape with a predetermined gap. In the needle valve and the paint spray nozzle, the spray amount of paint continuously changes at least during the first half of the movement stroke by the trigger portion, and the paint spray amount is substantially the same or small in the remaining movement stages. The coating apparatus according to claim 5 or 6 , wherein the coating apparatus is set so as to be changed in a suitable manner and is suitable for blurry painting work.