JP2008161788A - Powder coating spray gun - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily enable the coating fitted to the shape or coating condition of an object to be coated by arbitrarily adjusting a pattern shape on this side as a powder electrostatic coating spray gun by an operating person. <P>SOLUTION: In this powder coating spray gun, a powder containing air and held to a fluidized state is sent to the jet orifice provided to the leading end of the spray gun and the powder is sprayed on the object to be coated from the jet orifice while side surface air ports for jetting compressed air toward the powder jet stream are provided on both sides mutually opposed with respect to the axis of the jet stream. Respective regulation valves capable of adjusting the center air jetted from the circumference along the jet stream from the jet orifice and the flow rates from the side surface air ports are coaxially provided to the spray gun. The respective regulation valves are concentrically arranged to be provided to the side surface of the spray gun. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a configuration in which a spray pattern can be adjusted in accordance with spraying conditions in a spray gun for powder coating in which a powder coating is sprayed and generally applied to an object to be coated by the action of static electricity.

Among many coating methods, powder coating uses a solvent and does not use a solvent compared to coating with a liquid paint that forms a coating film by drying. Therefore, it can save resources and prevent the emission of volatile organic compounds. Therefore, there are advantages such as being environmentally friendly and having excellent coating strength. Further, it is known as a coating method that can collect and reuse a paint that has not been applied to an object to be coated, and is excellent in effective use of resources.

On the other hand, among various powder coating methods, powder coating by a general-purpose spray gun is widely used as a coating method capable of dealing with a wide range of objects to be coated. Normally, powder coating is sent to the spray gun in a fluidized state by compressed air, sprayed from the spray port provided at the tip of the powder coating spray gun, and further coated by the action of static electricity from the high-voltage charged electrode. It is applied to things.

The conventional powder coating supply is fed with a relatively large amount of air by an ejector pump, so the spray port of the powder electrostatic coating spray gun has a relatively large diameter and a reduced flow rate. In addition, a baffle is placed in front of the spray port to suppress the spray flow rate that goes straight, so that the effect of applying static electricity is not hindered.

On the other hand, in order to perform efficient painting with a spray gun, the spray flow must be adjustable depending on the shape of the object to be coated. The speed of the spray flow is mainly raised as a factor of the coating efficiency, as a factor of forming a uniform paint surface with a spray pattern shape, and for performing efficient painting according to the size of the paint surface. It is considered important. In other words, it is possible to obtain an average film thickness by spraying with a uniform pattern with a large spread over a large area, and the workability is also improved. These are also apparent in spray guns for liquid paints with a long history. It is said that.

In powder coating, powder paint that has not been applied to the object to be coated is characterized by being collected and reused. However, reused powder is inevitable to be contaminated with impurities, so new powder paint is used. It is important to improve the coating efficiency with the use of a spray, and it is desirable to efficiently spray in an optimum pattern on the object to be coated.

As described above, since many powder spray guns have been supplied with powdered paint together with compressed air, the spray force of air is used as it is, and the spray pattern depends on the size, shape and arrangement of the baffle. The method of adjusting by etc. was taken.

Needless to say, a small spread pattern is necessary for narrow gaps or narrow shapes in the object to be painted, and a large spread pattern is required for objects having a flat and wide painted surface. The pattern can be changed using the technique described in Japanese Patent Application Laid-Open No. 54-24953, which obtains the spread of the pattern by colliding the spray flow from the two spray ports opposed to each other, and the slit-shaped spray port. As a technique for this, a method disclosed in Japanese Patent Laid-Open No. 62-163758 has been considered.

However, all of these techniques change the spray port, and are insufficient in spray state and operability as pattern adjustment, and some improvements are required for practical use. In particular, when an operator operates a spray gun according to the state of spraying, an apparatus that can be easily adjusted to desired conditions is desired even during a painting operation.

In other words, the conditions of the object to be coated are often changed in a general-purpose powder spray gun, and in order to perform efficient and high-quality coating, it is necessary to perform coating while appropriately selecting and adjusting the state of spraying. It is necessary and desired that the above-described pattern adjustment can be performed with a simple and easy operation.

JP 62-163758 A JP 54-24953 A

The present invention is a spray gun for powder coating that uses static electricity, and the pattern width is adjusted by jetting air, and the pattern with the spray width corresponding to the shape of the object to be coated enables the optimum spray state for coating. An object of the present invention is to provide a spray gun for powder coating that can improve the coating quality and productivity by configuring the operation itself easily and easily at the hand of the spray gun.

The device is an oval or oval shape that is said to be the easiest to apply, depending on the coating conditions including the shape and part of the object to be coated. It is to improve the painting efficiency and quality by making it possible to easily adjust the thickness to the optimum pattern width. In addition, the spray pattern can be changed immediately even during spray coating, and it is possible to easily obtain the optimum conditions while checking the spray state. To provide a body spray gun.

The powder containing air and fluidized is sent to a jet port provided at the tip of the spray gun, the powder is sprayed onto the object to be coated from this jet port, and compressed air is jetted toward the powder spray flow The side air port is a spray gun for powder coating provided on both sides opposite to each other with the spray flow as an axis, the central air sprayed from the surroundings along the spray flow from the jet port, and the flow rate from the side air port Each of the control valves that can be adjusted is provided on the spray gun coaxially.

Each control valve is configured so that the flow rate can be adjusted independently, and is arranged concentrically on an axis intersecting the spray axis of the spray gun, and an adjustment knob is provided on the side surface of the spray gun body.

The adjustment air injected to adjust the pattern collides in the direction intersecting the powder from the injection port for the powder paint that has already been supplied and sprayed to the injection port in the flow state including the spray air. Therefore, the jetting power of the powder is affected by the jetting, and the stronger the air for pattern adjustment, the smaller the jetting amount, which is contrary to the purpose of widening the spray region.

According to the present invention, in addition to the pattern adjustment air, the center air is jetted, and the straight air is applied by the air along the spray flow to prevent the amount of jetting from decreasing. The center air is appropriately adjusted according to the strength of the powder, and the amount of sprayed powder and the spray pattern can be maintained in any desired state.

These valves, which adjust the flow rate of the adjustment air and auxiliary air, are directly installed in the supply path of the spray gun, improving operability and making corrections as necessary while checking the spray state during painting. Efficient painting can be performed under optimum conditions. By arranging each valve on the same axis, the arrangement of the spray gun can be simplified, and it can be made compact, and it can be linked to a reduction in size and weight, so that an effect of reducing the burden on the operator can be obtained.

Furthermore, by arranging them concentrically in one piece, the adjustment knobs can be arranged coaxially at the same position. During operation, adjustment can be performed immediately without changing the fingers at almost the same position. The operability is further improved. Normally, the operator holds the spray gun in his hand and paints forward, but at that time, by installing a control valve on the side of the spray gun, when operating with other hands without the spray gun , It can be operated naturally as it is, and it becomes easier to handle.

The adjustment of the pattern width can be easily performed with the control valve provided in the spray gun, and the adjustment at hand can be easily performed without interrupting the operation, thereby reducing the burden on the operator. Furthermore, as with conventional powder coating, adjustment of powder or control air can be performed by using a control device provided separately, and the burden on the cost and maintenance can be reduced. Even if it is simplified by the mechanical structure of the air passage provided in the spray device, the usability and function can be increased.

FIG. 1 shows an overall cross section of a powder coating spray gun according to an embodiment of the present invention, and FIG. 2 shows the tip of the spray gun as a cross sectional view. The gun body 1 has a powder nozzle 3 constituting a spraying device attached to the tip, and a cap 2 attached concentrically with the powder nozzle 3 is detachably attached by a cover 4. The barrel portion 5 extends rearward, connects a handle portion 6 provided at a lower portion thereof with a tip, and a high voltage generator 7 is disposed rearward.

This embodiment shows an example of a manual type electrostatic powder hand gun. A hose fixture provided at the lower end of the handle portion 6 at the rear part is connected to the paint supply port 10 at the tip part through the outside of the gun. Is attached. The lower end of the handle part 6 is provided with a supply terminal for power supplied to the high voltage generator 7 and a supply port 12 for compressed air supplied to the tip part. The high voltage output is connected to the charging electrode 34 disposed at the center of the powder nozzle 3 from the high voltage terminal 71.

The tip of the gun is arranged with a powder nozzle 3 screwed into the gun body 1 at the center, and a cap 2 is placed so as to surround the tip, and the gun 4 is assembled integrally with the gun body 1 by a cover 4. The cover 4 can be screwed in and out by hand, and the cap 2 can be attached and detached at appropriate times so that it can be easily replaced with a cap of other specifications, cleaned or the like.

The powder nozzle 3 is provided with a powder passage 31 penetrating in the center thereof, and on the outer side thereof, a screw 32 that is screwed and fixed to the main body side is provided at a rear end portion, and two air provided on the gun main body 1 side. A sheet 33 that partitions the passages 13 and 14 is provided, and has a function of branching the passage that is sent forward of the powder nozzle 3.

As shown in FIG. 3 with a view seen from the left side of FIG. 2, the cap 2 is formed on the outer side of the cylindrical outer diameter portion 22 of the jet port 21 opened at the tip of the powder nozzle 3 at the center. A central opening 24 serving as an air outlet is formed by forming an annular gap 23, and a corner 25 is formed on the outer peripheral side thereof so as to project symmetrically about the central axis of the spray. Square air holes 26 are respectively provided inside the corners, and pattern forming adjustment air ports 27 directed toward the axis of the central port are opened. The size, the injection angle, the number, and the like of the adjustment air port 27 are selected according to the spray adjustment balance. In the embodiment, two each are provided. By providing the adjustment air port 27 at the corner portion 25 that protrudes, the operator can easily determine the direction in which the spray pattern is formed, and the workability can be improved.

When the cap 2 is attached to the powder nozzle 3, the first air passage 13 communicates with the central port 24 and the second air passage communicates with the angular air hole 26 among the two air passages. A cap sheet is provided at a contact portion between the powder nozzle 3 and the cap 2. As a result, the first air passage 13 formed at the tip of the gun body communicates with the central port, and the second air passage communicates with the adjustment air port 27.

In the powder passage 31 of the powder nozzle 3, as shown in FIG. 1, an electrode 34 charged with a high voltage supplied from the high voltage generator 7 at the rear of the barrel is provided. The electrode 34 is formed by covering an insulating holder 35 with a conductive electrode with only its tip exposed, and is detachably attached to the gun body 1 so as to be positioned in the powder passage. Further, the powder passage 31 communicates with the paint supply port 10 of the gun body 1 so that powder supplied from a separately provided powder supply device is sprayed from the ejection port 21.

An adjusting valve 15 is provided at the rear part of the barrel part 5 and near the attachment part of the handle 6, and compressed air fed from the supply port 12 below the handle 6 is supplied to the first air passage 13 and the first air passage through two air circuits. 2 Has the function of adjusting the amount of air supplied to the air passage 14. The configuration of the regulating valve 15 will be described as one embodiment with reference to FIG. 4 showing the AA cross section of FIG.

The valve chamber in which the control valve is accommodated is formed by a first chamber 51 having a small diameter and a second chamber 52 having a large diameter. Yes. In front of and behind the respective valve seats 53, 54, inlets 53 A, 54 A and outlets 53 B, 54 B are provided, and the inlets communicate with the supply port 12. In the figure, the passages are shown as different paths, but may be configured to branch immediately before.

Although not shown, the first outlet 53B communicates with the central port 24 via the first air passage 13 formed at the tip of the gun body, and the second outlet 54B similarly passes through the second air passage 14. Via the adjustment air port 27. The valve body has a concentric double structure in which the first valve body 17 penetrates the center of the second valve body 18. The first valve body 17 contacts and separates from the first valve seat 53 to adjust the opening degree, and the second valve body 18 contacts and separates from the second valve seat 54 to adjust the opening degree. The valve bodies 17 and 18 are moved forward and backward by screwing with the screw portions 35 and 36 formed in the main body by rotating the knobs 19 and 20 provided at the end portions, respectively, and the opening degree is adjusted. Is done.

As shown in FIGS. 5 and 6, the knobs 19 and 20 are provided coaxially on the side of the gun body, slightly above the grip, and in front of each other, so that both control valves can be operated immediately at the same position. The optimum spray state can be selected while maintaining a natural posture in which the spray state can be confirmed even during spraying.

In the powder coating spray gun having the above-described configuration, the powder coating material is fed into the spray gun coating port 10 in a state of being fluidized together with compressed air by a supply device provided separately. In this case, various types of pumps are used as the supply device. In order to effectively use the present invention, a positive displacement pump using a cylinder / piston is used. According to this pump, the powder is sucked into the cylinder in a flowing state, discharged by a piston, and can be supplied by a small amount of compressed air using air for feeding and supplying, if necessary. Spraying can be performed in a state where the influence of compressed air is small.

In the case of an injector pump that is representative of powder supply, a large amount of compressed air is used for supply, and since the air is supplied to the spray gun by the air, the spraying force by the compressed air is strong. Control becomes difficult. On the other hand, in the case of the positive displacement pump, the amount of air at the time of powder supply is about one-tenth, and the spray flow can be easily controlled. As an example of this type of pump, powder is sucked into the cylinder by the movement of a piston that reciprocates in a cylindrical cylinder, discharged together with a small amount of air jetted into the cylinder for fluidization, and then passed through a supply hose. There is a pump that feeds the body spray gun. The supply amount of the powder is set to a range in which about 50 to 400 g per minute is often used.

The powder sprayed from the jet port 21 in the center is spread flat in a state where the whole is crushed by the adjustment air ejected from the adjustment air ports 27 provided on both side surfaces. This spread is gradually widened by increasing the amount of air ejected from the adjustment air port 27 by the knob 20, and is selected according to the coating width of the object to be coated.

However, when the flow velocity from the adjustment air port 27 is fast for the flow rate, that is, when the amount of the blown air is too large, the central part may be blown away, and the distribution of spray particles may be uneven. It is necessary to adjust within the range of appropriate balance. In the case of the present embodiment, the first valve body 17 of the adjustment valve is opened by the knob 19 and the air from the center port 24 is injected to maintain the balance with the adjustment air and to create appropriate spray conditions.

If conditions in different ranges are required, the range in which the pattern can be adjusted is applied to a wider range of sprays by selecting different caps such as the size and number of the central air port 24 and the adjustment air port 27 or the injection angle. Is possible. In the embodiment of FIG. 2, two adjustment air ports 27 are provided on the front and rear sides so that the adjustment air can be used in a wide range.

In this example, it is natural that the amount of adjusted air depends on the amount of powder discharged, but in one example, the amount of adjusted air is gradually increased with respect to the discharge amount of 300 g per minute, By doing so, a circular pattern of about 50 mm could be expanded to a pattern width of about 400 mm.

As mentioned above, if the pattern width expanded by the adjustment air exceeds the certain range and the adjustment air is increased, the density of the powder decreases in a state where the central portion is blown away, and the finish is uneven with respect to the coating. Result. In the present invention, the amount of compressed air ejected in parallel with the spray flow formed by the annular gap provided around the jet nozzle 21 is increased in the same manner as described above, and the forward spray flow is strengthened while enclosing the spray flow. It is possible to prevent the decrease in the density of the central portion without affecting the powder ejection amount and maintain the average distribution state.

On the other hand, when spraying the deep corners of the object to be coated, an edge effect due to static electricity is also added, and it will not enter unless the spray flow is vigorous, causing uneven coating, Similarly, by adding the central air from the central port 24 with the knob 19, the linear force can be increased and the spray particles can be concentrated in the central part. It is possible to immediately select a spray in a convenient state and improve the above-mentioned problems.

Various configurations and balances of the jet port 21, the center port 24, and the adjustment air port 27 that form the spray state are conceivable depending on the conditions of the powder spray, and the individual sizes and dimensions are not limited. The spraying conditions must be selected according to the properties of the paint and various coating conditions. For this reason, the flow rate of the adjustment air and the center air can be individually adjusted, and the operation and effects can be further increased by adopting a configuration in which the operator can directly operate.

It is sectional drawing which shows the whole spray gun for powder coating of this invention.
It is sectional drawing which showed the front-end | tip part of the spray gun partially. It is the side view which looked at the front-end | tip part of the spray gun from the left side of FIG. It is sectional drawing of the control valve part integrated in the gun main body. The external view of the spray gun for powder coating of this invention is shown. FIG. 6 shows an external side view of the spray gun as seen from the left in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gun main body 2 Cap 3 Powder nozzle 6 Handle 7 High voltage generator 10 Paint supply port 12 Supply port 13 First air supply channel 14 Second air supply channel 15 Adjustment valve 19, 20 Knob 21 Jet port 22 Outer diameter portion 23 Gap 24 Center port 27 Adjusting air port 31 Powder passage 34 Charging electrodes 35 and 36 Threaded portion

Claims (3)

The powder containing air and fluidized is sent to a jet port provided at the tip of the spray gun, the powder is sprayed onto the object to be coated from this jet port, and adjusted air is jetted toward the powder spray flow In a powder coating spray gun provided with side air ports on opposite sides with the spray flow as an axis, a supply path for central air sprayed from the periphery along the spray flow from the jet port, and the side air ports A powder coating spray gun in which a flow rate control valve is provided in each supply path, and the control valves are provided coaxially.
The spray gun for powder coating according to claim 1, wherein each of the control valves is capable of independently adjusting the center air and the adjustment air.
2. The powder coating spray gun according to claim 1, wherein each of the control valves is provided concentrically in a direction intersecting a spray axis of the spray gun, and each control knob is provided on a side surface of the spray gun body.

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