JP2008142586A - Spray gun apparatus for powder coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spray gun apparatus for powder coating which overcomes problems that powder stream jetted from the jetting port is weak at the time when conveyed and hardly controls the atomization in a spray gun performing the pattern adjustment of a powder spray gun with air jetted from the horn. <P>SOLUTION: In the powder coating spray gun to spray the powder mixed with conveying air and supplied to the spray gun in a fluid state, from the jetting port of the distal end through the powder supplying pathway, to an air cap provided with the jetting port of the adjusted air to jet to the atomization axis of powder and to form the atomization pattern, the air cap in which the central port forming the annular air mouth is provided to the surrounding of the jetting port is arranged. An adjustment valve of the amount of jetted air is installed at the supply pathway connected with the central port and the straightness of the atomization flow is adjusted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an apparatus capable of adjusting a spray pattern according to spraying conditions in a spray gun for powder coating in which a powder coating is sprayed and applied to an object 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 spray gun is highly versatile and widely used as a coating method that can deal 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.

In other words, powder coatings themselves are solid particles, so they do not have their own stickiness / coating properties, so they are applied to objects to be coated by static electricity. Have been widely used. The method using electrostatic coating has the advantage of reuse because the powder paint that has not been applied to the object can be collected and collected as it is due to its solid nature, and spraying from the spray gun is effective. The need to be appropriately sized was not so much required.

In addition, the coating effect due to static electricity has a certain film thickness retaining property due to the electrostatic effect even when the amount of spraying is large, and it is not necessary to consider the painting skill and spraying range. For this reason, in powder coating spray guns, more emphasis has been placed on maintaining a proper spray particle velocity than on the distribution and size of the particles in the spray.

When supplying powder paint to a spray gun, the conventional method is fed with a relatively large amount of air by an ejector-type pump. The flow rate is reduced with a relatively large diameter, and a baffle is arranged 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.

In recent years, with the expansion of powder coating, the diversification of objects to be coated has progressed, and it has been used not only for coating a large amount of products with the same paint as in the past, but also for small quantities of many types of coating. Yes. For this reason, even in powder coating, there is an increasing tendency to perform efficient spraying with an appropriate spray pattern according to the shape of the object to be coated and the state of the coated surface, and to perform sprayed powder paint without collecting it. ing.

In order to perform efficient painting with a spray gun, it is necessary to be able to adjust the spray flow according to 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.

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, there is a demand for an apparatus that can easily adjust the spray state to a desired condition even when the operator is operating a spray gun even during a painting operation.

JP 62-163758 A JP 54-24953 A Japanese Patent Publication No. 6-85895

The present invention relates to a spray gun for powder coating using static electricity, in which the pattern width is adjusted by blowing air, and the spray state optimal for coating is achieved by the pattern with the spray width corresponding to the shape of the object to be coated. The aim is to expand powder coating by providing a spray gun for powder coating that can be applied and can improve the coating quality and productivity.

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 possible to easily adjust the thickness to the optimum pattern width and to improve the painting efficiency and the painting quality as a configuration capable of setting the speed of the spray particles to the optimum situation. In addition, even if the spray pattern is changed during spray coating, it can be changed immediately, and it is possible to obtain the optimum conditions while checking the spray state. To provide cancer.

In a powder coating spray gun that mixes air and sends fluidized powder to a spray port provided at the tip of the spray gun, and sprays the material to be coated from this spray port. The cap is provided with an adjustment air port that forms a spray pattern by injecting air that collides with the velocity component forward of the spray from the outside. A central port forming an air port is formed, and the cap is detachably disposed. The adjustment air port is provided at a corner formed to protrude from the outer periphery of the cap.

The supply path that communicates with the center port is provided with a control valve that independently adjusts the flow rate supplied to the center port, and the flow rate is adjusted independently. Similarly, an adjustment valve that supplies the adjustment air port for pattern adjustment is provided so that each can be adjusted independently.

A high voltage charging electrode is arranged at the center of the jet outlet, and a high voltage from a high voltage generator built in the spray gun is connected to charge the spray flow.

According to the powder spray gun of the present invention, the powder is always sprayed from the central spray port in a stable state, and adjustment air is blown to the spray flow so as to crush the whole from both side surfaces. The normal circular spray pattern can be made flat, and the pattern width increases as the amount of the adjustment air increases. Therefore, if the shape of the object to be coated is widened, the pattern width can be widened to provide uniform coating over the entire surface, less spraying operations can be performed, and coating efficiency can be increased.

Since the adjustment air is caused to collide with the powder intersecting the powder from the jet outlet, the jet power of the powder is limited by the jetting, and the spray conditions such as the jet quantity are changed. For example, before the adjustment air collides with the spray flow, the center air is injected along the spray flow and the flow rate can be adjusted. Therefore, the center air is adjusted according to the strength of the adjustment air, and the powder The spraying condition can be maintained without limiting the amount of jetting.

Further, in the present invention, a straight air force can be applied to the spray flow by providing a central air port around the ejection port from which the powder is ejected and ejecting the adjustment air. The central air from the central air port can adjust its flow rate independently of the adjustment air, and the spray flow can change the amount of spray and the state of the spray pattern according to the shape of the object to be coated and the state of the coating part. It can be selected and adjusted to the optimum state. If necessary, caps with different specifications can be exchanged to obtain a spray gun that meets a wider range of painting conditions.

For example, when painting in gaps or narrow corners that did not enter with conventional spray guns, it is easy and quick to increase the compressed air from the auxiliary air port and force straight forward spray, so that complex shapes Powder coating is also possible on the object to be coated without impairing workability.

Many powder coatings use electrostatic coating, and in the present invention, the charged electrode that charges the powder and forms the electric field to the object to be coated is placed at the tip center in the center of the jet nozzle. Therefore, the strongest and most efficient charging is possible, and a stable electrostatic effect can be obtained even when the spraying conditions are changed, for example, by adjusting the spraying pattern.

FIG. 1 is a sectional view of the tip of a powder coating spray gun according to the present invention, and FIG. 2 is an overall sectional view of the spray gun. 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 powder electrostatic hand gun. A supply hose 9 is supplied from the hose fixture provided at the lower end of the rear handle portion 6 to the paint supply port 10 at the tip portion through the outside of the gun. Is attached. The lower end of the handle portion 6 is provided with a supply terminal for supplying power to the high voltage generator 7 and a supply port 12 for supplying compressed air to the tip portion.

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 14 communicates with the angular air hole 26 among the two air passages. In addition, 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 14 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 HH 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 coaxial 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 formed on the main body by adjusting the knobs 19 and 20 provided at the end portions, and the opening degree is adjusted.

In the case of the present embodiment, the high voltage generator 7 is built in the gun body 1, and the high voltage output is connected from the high voltage terminal 71 to the charging electrode 34 disposed at the center of the powder nozzle 3. It has become. There are several methods for charging the powder, and the first invention of the present application is not limited. However, the powder supplied from the powder supply apparatus is stable when it passes through the jet nozzle. The powder is charged at a stage where it is in a fluid state and is not affected by the subsequent jet collision of the pattern adjusting air. Thus, when the state of spraying is changed, for example, when the ratio of compressed air used differs depending on the coating conditions, the method of positioning the tip of the charged electrode in the ejection port 21 works effectively.

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 in a range in which about 50 to 400 g per minute is usually 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 increases as the flow rate of the compressed air increases, and is selected according to the coating width of the object to be coated.

However, if the size of the adjustment air port 27 is small for the flow rate and the flow velocity is high, the central portion may be blown away, and the distribution of spray particles may be non-uniform. By selecting a cap that can adjust the pattern, a wider range of spraying 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.

On the other hand, as described above, when the pattern width expanded by the adjustment air exceeds the certain range and the adjustment air is increased, the density of the powder is reduced in a state where the central portion is blown away, and the pattern width is not uniform. This results in a finished product. In the present invention, the spray flow is wrapped without increasing the back pressure in the powder nozzle 3 by the compressed air jetted in parallel with the spray flow from the central port 24 formed by the annular gap provided around the jet nozzle 21. In this state, the forward spray flow can be strengthened, the density of the central portion can be prevented from decreasing, and the average distribution state can be maintained.

In addition, when spraying deep corners of the object to be coated, an edge effect due to static electricity is also added, and it becomes a situation where the spray flow does not enter unless there is momentum, and uneven coating occurs. Similarly, by adding the central air, the straight running force increases and the spray particles can be concentrated in the central portion, and it is possible to select the spray in a convenient state and improve the above-mentioned problems.

Various configurations and balances of the jet port 21, the central port 24, and the adjustment air port 27 that form the spray state are conceivable depending on the conditions of the powder spraying, and individual sizes and dimensions are not limited. The spraying conditions must be selected according to the properties and various coating conditions. Therefore, the flow rate of the adjustment air and the central air can be individually adjusted, and the application effect is further increased by the configuration in which the operator is controlled directly or automatically based on the set conditions. be able to.

These techniques can obtain an effect as a spray gun for powder coating, but can be most effective in electrostatic powder coating in which coating is performed by electrostatic force. In electrostatic powder coating, various methods can be used to charge the powder, and in addition to internal frictional charging, a configuration with a large opening at the center of the jet outlet is possible, so that electrostatic charging can be performed without being affected by spraying. Since it becomes easy to arrange the charging electrode for painting, a method in which a charging electrode is provided at the tip can be used without any problem. When a charged electrode is provided, a high-function, high-productivity spray gun for powder coating can be obtained without sacrificing operator operability by incorporating a high-voltage generator for charging in the spray gun body. Can be obtained.

It is sectional drawing which shows the front-end | tip part used as the spraying apparatus part of the spray gun for electrostatic powder coating of this invention. It is sectional drawing which shows the whole spray gun for electrostatic powder coating of this invention. It is the side view which looked at the spraying device part from the left of FIG. It is sectional drawing of the control valve part integrated in the gun main body.

Explanation of symbols

1 Gun body 2 Cap 3 Powder nozzle 6 Handle 7 High voltage generator 10 Paint supply port 12 Supply port
13 First Air Supply Path 14 Second Air Supply Path 15 Adjustment Valves 19 and 20 Knob 21 Jet Port 22 Outer Diameter Portion 23 Clearance 24 Center Port 25 Corner Portion 27 Adjustment Air Port 31 Powder Passage 34 Charged Electrode

Claims (5)

In the powder coating spray gun that sprays the powder mixed with the carrier air and supplied to the spray gun in a flowing state from the jet outlet at the tip through the powder supply path, with respect to the spray axis of the sprayed powder, An annular air port is formed by forming a gap between the outer part of the jet port and a cap provided with an adjustment air port that jets air that collides with the velocity component forward of the spray from the outside to form a spray pattern. A spray gun apparatus for powder coating, in which a cap having a central opening to be formed is detachably disposed.
The spray gun device for powder coating according to claim 1, wherein the adjustment air port is provided at a corner portion protruding from an outer periphery of the cap.
2. The spray gun apparatus for powder coating according to claim 1, wherein a supply path communicating with the central port is provided in the spray gun, and a control valve is provided in the supply path so that the flow rate can be adjusted independently.
2. The spray gun apparatus for powder coating according to claim 1, wherein a supply passage communicating with each of the center port and the adjustment air port is provided in the spray gun, and an adjustment valve for adjusting a flow rate is provided in each supply passage.
2. A spray gun for powder coating according to claim 1, wherein a high voltage charging electrode is arranged in the center of the jet outlet, and a high voltage from a high voltage generator built in the spray gun is connected to charge the spray flow. apparatus.

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