JP5336763B2 - Spray gun for internal coating. - Google Patents

Description

The present invention relates to a spray gun used when atomizing a paint or the like with compressed air and painting a narrow surface such as the inside of an article.

An air spray gun for atomizing a paint using compressed air to form a painted surface is widely used in various fields because it can deal with the uniformity of the finished surface, a wide range of objects to be coated, and the paint. In such spray coating, since a relatively large amount of compressed air is used, generally the outside of an article is often painted. However, the inner surface is often painted to protect the article and to form a necessary film, and an excellent coating quality is often required in terms of aesthetics.

Up to now, inner surface coating has been used as a spray gun for coating annular and cylindrical inner surfaces. By inserting a spray gun atomizer into the interior, a spray flow is formed in the lateral direction to rotate the inner surface of the object to be coated. A spray gun called a single-angle gun has been used. Such a spray gun is also used when painting the inside of a narrow groove that is difficult to paint with a normal spray gun. As seen in Japanese Patent Publication No. 2006-263591, an atomizing device sprayed in the lateral direction on a pipe-shaped tip is provided.

With the diversification of the objects to be coated and the improvement in required coating quality, the inner surface coating is also required to have a function capable of responding to many demands, and the technique described in the above publication can adjust the pattern sprayed in the lateral direction. It has been improved to be able to. However, as a result, the structure becomes complicated and larger than in the case of merely spraying.

Also, since a large amount of compressed air is used for a small amount of paint, atomization is promoted and the quality of the coating film is good. On the other hand, the pattern is small and the amount of spray is limited. It is held down low.

On the other hand, as a relatively simple structure, there is an internal mixing type spray gun for internal coating that mixes paint and compressed air inside the atomizing device to form an atomized state and sprays the spray flow from the atomizing port. is there. As illustrated in Japanese Utility Model Publication No. 5-45402, since it is easy to freely set the spray port, the spray flow can be selected in the lateral direction and the rear, and according to the coating position of the object to be coated. The advantage is excellent compatibility.

In this system, the structure is simplified and the size can be easily reduced. However, since the mixture is mixed inside, there are many restrictions on the spraying conditions such as the amount of paint sprayed and the amount of compressed air sprayed or pressure, etc. It cannot respond to diversification of film formation. This is atomized by the balance between the paint and the atomized air inside the spray gun. For example, if the paint pumping pressure is increased to increase the paint ejection amount, the air pressure or the air amount for that must be adjusted. There is a difficulty in handling such that proper atomization cannot be obtained and adjustment is required.

In addition, from the danger of spraying and depositing paint on the inside and spraying port from the spraying method, it may adhere to the object to be coated when it peels off, resulting in poor coating or clogging. There are problems such as requiring cleaning and increasing the burden on the operator in handling and maintenance.

In addition, as a method that is convenient for painting the cylindrical inner surface, an annular paint outlet and a concentric annular air outlet are provided as a method for obtaining a spray shape spreading forward in a circular pattern around the atomizer. There is known an atomizing device provided with For example, by providing a real Sho 58-30596 and JP fair 2-20302 Patent as seen in Japanese configuration, uniform and fine spray particles are obtained throughout, the apparatus capable of performing high-quality paint It is used as one.
JP-A-5-345152 Japanese Utility Model Publication No. 5-45402 Japanese Utility Model Publication No. 58-30596 Japanese Patent Publication No. 2-20302

The conventional single-angle spray gun is provided with a paint nozzle provided at the center of the tip of a pipe, and sprayed and atomized paint from an annular air port surrounding the nozzle tip is provided on one side of the square air ( The pattern is deflected by spraying obliquely forward. Therefore, since the bending angle of the pattern is small and the spread is small, the coating efficiency is low, and even if it is possible to cope with an increase in the amount of ejection, there is a drawback that the spray particles become coarse and the finished quality is lowered.

In the case of the internal mixing type, the spray amount changes depending on the balance between the spray pressure and the supplied paint pressure, and there are restrictions on the spray conditions for stabilizing the spray, and there is a limit to improving the quality. However, there is a problem that does not reach the atomization performance of the external mixing method in which paint and compressed air are mixed. Also, since it is necessary to pump the paint, a paint supply device is indispensable and cannot be used easily. Further, as described above, there is a problem in the maintainability due to the adhesion of the paint due to the paint mixing inside, and the burden on the operator and the decrease in productivity must be solved.

In particular, when painting an inner surface with a small diameter, the spray gun is prioritized to make the tip of the spray device small as mentioned above, and it is required to increase the coating efficiency and improve the coating quality by spraying. . Specifically, the atomizing device at the tip can be miniaturized as a gun for internal coating, and the paint is not limited to pumping using a supply device such as a pump, but can be applied by negative pressure suction with compressed air As a configuration that is not restricted by the coating conditions, it is easy to adjust the spraying amount of the paint and the spray pattern and spray state associated with this, and it is suitable for versatile use with an atomizing device with excellent atomization. The problem is to obtain a spray gun for internal coating.

An inner surface that has a pipe-shaped paint passage with a paint valve at the tip and an air pipe that forms an air passage around it, and supplies the paint and compressed air from the rear operation body to spray from the atomizer at the tip In the spray gun for painting, the atomizing device at the front end includes a nozzle that forms a large number of paint outlets that open in the circumferential direction from the center of the spray axis, and an obliquely rearward side that is close to the opening of the outlet. And an air nozzle that forms an annular air port that expands to the front, and a deflection plate that blocks the jet flow in front of the air port and diffuses it to the surroundings.

The air nozzle has a gap between a tapered surface that terminates immediately before the paint outlet is opened and an inner tapered surface of the air cap that is formed with an inner tapered surface that expands forward along the tapered surface at the front end. Consists of. This gap is adjusted by adjusting the forward / backward position of the air cap.

An air amount adjusting device is provided on the upstream side of the air pipe communicating with the air nozzle so that the amount of air ejected from the air nozzle can be adjusted.

The deflecting plate extends in the circumferential direction slightly forward from the opening end of the paint jet outlet, has an outer diameter sufficient to collide with the jet airflow from the air nozzle, and tilts vertically or obliquely forward in the axial direction. Have a surface to do.

According to the present invention, a spray gun capable of connecting an atomizing device at a tip portion from a spray gun main body with a double pipe of paint and air and installing a thin tip portion on the inner surface of an object to be coated. As a result, the atomization device at the tip can be specified in a wide range of spraying conditions, and can be made compact. The atomizing device injects compressed air from a large number of outlets directed in the circumferential direction by injecting compressed air from the annular air port that expands, and mixes the compressed air with the jetted paint from the outlet. In addition, the inner surface in the spraying direction can be painted by colliding with the change plate and directing it toward the outer peripheral direction.

Therefore, unlike the case of the conventional internal mixing method, the paint is not supplied under pressure, so it can be used easily without a paint supply device, etc., and spray control is also performed by adjusting compressed air etc. Can do. Furthermore, the coating can be forcibly supplied and sprayed in a state where a required amount of the coating is ejected, and the application can be expanded.

The spray direction, spray pattern, and spray particle state are adjusted by adjusting the annular gap forming the air nozzle or by the air amount adjusting device with respect to the spray amount of the paint from the air port. Can be changed according to the conditions of the object to be coated. When painting a substantially cylindrical inner surface, if the atomizer is located in the center and the spray is made with a narrow slit, the entire inner surface can be painted simultaneously, and high production efficiency can be obtained.

In addition, since the atomization method is based on external mixing, various patterns and coating conditions can be set by adjustment without limiting the range of coating due to restrictions on spraying conditions. In addition, the collision effect by the deflecting plate is added and fine and soft spraying becomes possible, and the quality of the finished painted surface can be maintained in the same manner as the outer surface coating.

In addition, by directing the tilt angle of the deflecting plate to the front and increasing the air flow, the spray flow becomes stronger in the forward direction and can form an annular spray pattern in a widened state. In addition, the application can be expanded such that the front surface can be painted.

FIG. 1 shows the overall structure of a spray gun according to an embodiment of the present invention. The spray gun is an example of an automatic gun, and an atomizing device section 3 is attached to the tip of a main body 1 at the tip of a neck 2 extending in a pipe shape. The compressed air for atomization opens the air valve 5 by the operation of the piston 4, and is sent from the air passage 6 through the passage 13 to the atomizing device portion 3 at the tip end from the air pipe 22 of the neck portion 2. The needle valve 23 passing through the center of the neck portion 2 is retracted by the retreat of the air valve 5, and the paint nozzle 31 provided at the tip is opened to eject the paint. The detailed structure for operating this type of automatic spray gun is well known and is not intended to limit the present invention, and therefore will not be described in detail.

FIG. 2 is a partially enlarged view of the connecting portion between the tip and the neck of the spray gun body. Supply of paint and air to the atomizer 3 is performed from the spray gun body side, and as shown in detail in FIG. 2, a nozzle base 12 to which a paint pipe 21 is attached is screwed to the body 1, and the interior is supplied with paint. It communicates with the mouth 11. The atomized compressed air passes from the rear part of the spray gun through the passage 13, passes through the inside of the air pipe base 14, and is sent to the air pipe 22 screwed into the air pipe base 14. The jam nut 16 is provided to adjust and fix the attachment position, and the position of the air pipe described later can be adjusted. The control valve 8 provided with a knob extended at the rear part of the main body 1 has a role of adjusting the amount of air flowing into the air pipe 22 from the passage 13.

The air pipe base 14 is detachably attached to the main body 1 by a cover 15, and the cover 15 also has a function of preventing leakage of compressed air sent to the air pipe 22.

As shown in detail in FIG. 3, the atomizer 3 has a paint nozzle 31 attached to the tip of the paint pipe 21 at the center and an air cap 32 provided at the tip of the air pipe 22 on the outside. They are arranged concentrically. As described above, the needle valve 23 whose tip abuts and separates is provided at the inner center of the paint nozzle, and the outlet side is screwed into the paint outlet passage 33 opened in the boss portion 34 of the deflection plate 35. A large number of jet outlets 36 are provided radially from the paint outlet passage 33 to the outer peripheral surface of the boss portion 34, and the paint discharged from the paint nozzle 31 is jetted radially from the jet outlet 36. The packing 37 is attached to prevent leakage from the paint outlet passage 33. The packing 37 may be a flat shape or an O-ring shape.

The outer periphery of the boss portion where the jet port 36 opens forms a tapered surface 38 that terminates immediately before the opening end of the jet port 36, and an inner tapered surface 39 formed along the tapered surface 38 at the inner circumferential front end of the air cap 32. An air gap 41 is formed between the two and the air nozzle 41. From the air nozzle formed by the gap between the two tapered surfaces, an air flow that is annular and spreads forward is ejected, and the gap is adjusted by the position at which the air pipe 22 integrated with the air cap 32 is fixed.

The paint nozzle 31 and the air cap 32 need to be concentric in configuring the air nozzle 41. As shown in the AA cross section of FIG. 4 and the BB cross section of FIG. A partial air passage 42 is provided to allow the air pipe and the air nozzle to communicate with each other, and an annular groove 43 is provided on the inner peripheral surface of the air cap 32, and an air flow jetted from the air nozzle 41 as an air flow reservoir. To equalize.

The compressed air injected from the air nozzle 41 collides with the deflecting surface 44 of the deflecting plate 35 provided to collide and diffuse in front of the air nozzle 41 and flows to the outside. The paint is sucked and ejected, and at the same time, mixed with the compressed air stream and atomized. It is desirable that the atomized paint has an outer diameter sufficient for the jet stream to collide so that it is radiated outward along with the stream by the deflecting surface 44. The deflecting surface 44 is provided at an angle substantially parallel to the injection port, and is formed with an inclination angle slightly forward in the case of FIG. In this case, the spray flow is directed forward, and an annular spray pattern is formed in front of the atomizing device if there is no coating surface at the position facing the injection port.

In the embodiment, a pattern having an outer diameter of about 200 mm is formed by an atomizer provided with twelve jet holes having an outer diameter of 7 mm and a diameter of 0.3 mm. The amount of paint sprayed can be increased by gradually increasing the pressurization pressure from the state of suction without pressure, and can be selected from about 50 to 300 ml per minute. The spray pattern increases as the pressure increases. There was a tendency to become more forward oriented. By adjusting the position of the air cap and changing the gap between the air nozzles, the amount of atomized air at the same pressure can be increased to promote atomization, and the spray pattern can be widened. Wide width can be selected.

FIG. 6 shows a cross section of an atomizing device section showing another embodiment. In this case, the injection port is opened in a direction substantially perpendicular to the axial direction of the air pipe, and the deflection surface is also formed in a disc shape accordingly. The air nozzle of the annular slit that expands toward the front spreads at an angle of about 45 degrees, collides with the deflecting surface in front of it, and the air flow velocity is reduced, resulting in a fine and soft spray flow Painting is done on objects.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows the whole structure of the spray gun which shows one Example of this invention. Sectional drawing which expanded and displayed partially the connection part of the spray gun main body front-end | tip part of FIG. 1, and a neck part. Sectional drawing which expanded the atomization apparatus part of FIG. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. Sectional drawing of the tip atomization apparatus part which shows the other Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gun main body 2 Neck part 3 Atomization apparatus part 12 Nozzle base 13 Air pipe base 23 Needle valve 31 Paint nozzle 32 Air cap 33 Paint outlet channel 34 Boss part 35 Deflection plate 36 Jet outlet 38 Tapered surface 39 Inner taper surface 41 Air nozzle 44 Deflection surface

Claims (1)

An inner surface that has a pipe-shaped paint passage with a paint valve at the tip and an air pipe that forms an air passage around it, and supplies the paint and compressed air from the rear operation body to spray from the atomizer at the tip In the spray gun for painting, the atomizing device at the front end includes a nozzle that forms a large number of paint outlets that open to the periphery from the center of the spray axis, and an annular air opening that opens forward from an oblique rear side of the outlet. an air nozzle forming, the annular front air inlet to block the jet flow is provided deflection plate to diffuse radially outward Ri name, said air nozzle is formed in the boss portion outer periphery of the deflector plate the coating material ejection opening A gap between the tapered surface that terminates immediately before the opening and an inner tapered surface that expands forward along the tapered surface at the front end and the axial position of the air cap can be adjusted. Consists of Spray gun for the inner face painting was characterized by.

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