JP5270842B2 - Spray gun for painting - Google Patents

Abstract

Lower spray gun trigger load is desired in view of worker protection and has been reduced by countermeasures including back pressure countermeasures for an air valve. The invention provides a needle valve of a spray gun with back pressure countermeasures to reduce trigger load of the gun. The spray gun has an air valve operated by a trigger and the needle valve for opening and closing a paint ejection opening. Spray air is taken out of a branch passage branched from a connection passage provided between an exit passage of the air valve and an air cap for atomization, supplied from a spray gun outer section via restriction passage to operation means directly connected to the rear of the needle valve and having a piston and a cylinder, and causes the needle valve to recede. A flow rate adjustment valve is provided in the restriction passage communicating with the branch passage to enable adjustment of the inflow amount of air into the cylinder.

Description

TECHNICAL FIELD The present invention relates to a technique for reducing the burden on a finger when operating a trigger in a hand-held spray gun that performs spraying by a trigger and enhancing the use safety of an operator.

There are several types of painting spray guns, depending on their application and function. The most commonly used and popular spray gun is a spray gun that uses compressed air to atomize paint and spray it onto the object to be painted. Many of the guns are hand-held spray guns, and this is an important factor for direct operation by the operator.

This type of spray gun normally controls the opening and closing of two valves, an air valve for injecting compressed air and a paint valve for injecting paint. These valves are configured to open the valve by a trigger and close the valve by a spring load that is interposed to close the valve when the finger is released, and resist the spring load when the trigger is pulled. Will be operated.

Fatigue due to repeated operation during painting operations is often cited as a cause of tendonitis, and it is desired that such a spray gun can reduce the load even a little. Furthermore, the opening area of the paint valve changes depending on the amount that the valve can be retracted structurally, and the amount of jetting can be adjusted, and the spring interposed at the rear of the valve is compressed to the set maximum load repeat.

In addition to the springs for closing the valves, the air pressure is supplied with the back pressure of the compressed air that is sent to the trigger valve, and also prevents leakage from the sliding part as the valve moves. There is a resistance of the sealing device to be used, and measures to alleviate each have been taken so far. The trigger operation can be reduced by using the lever principle, but there are limits to structural changes in consideration of downsizing and operability such as changing the position of the spray gun fulcrum and lengthening the trigger. There is.

The method of reducing the back pressure applied when opening the air valve requires reducing the area of the valve opening and lowering the supply pressure. However, it is necessary to maintain the amount of blowing air and the pressure required for the spray gun. Is an absolutely necessary condition for obtaining the function and performance of the spray gun and cannot be reduced.

As a method for reducing the back pressure, a structure for eliminating the back pressure applied to the rear portion of the air valve is disclosed in Japanese Utility Model Publication No. 5-43883. Further, as a force necessary for operating the paint valve, an operation mechanism using an air piston that is generally employed in an automatic spray gun or the like is known.

Especially for spray guns that require a large force to close the paint valve, the demand is strong, and there is known a technique of releasing the trigger and feeding the supplied air to the piston provided at the rear of the paint valve to retreat. The structure is shown in Japanese Utility Model Publication No. 47-2776. In this case, a special gun that sprays a material with higher viscosity than a general spray gun was devised due to its heavy trigger load. Operating air was directly introduced into the air piston and a part of the air was sprayed. It is to be sent as air.

Conventional general-purpose spray guns have not been adopted because there are problems with the relationship between necessity and operability to adopt a structure with an air piston. However, due to the increased awareness of safety and hygiene, the tendency of thin-film coating due to the small amount of jetting using high-grade paint increases, and the use of a paint valve that squeezes the spring compresses and increases the operating load. Due to the increase, the demand for reducing the trigger operation with a general spray gun is rapidly increasing.

If you can reduce the trigger with a general-purpose spray gun, which is generally used in large quantities, from the viewpoint of improving industrial productivity on the commercial side or the painter side, you can create a special spray gun. However, it is more economical than being used, and the burden and danger of the operator can be reduced, and convenience is increased.

Japanese Utility Model Publication No. 5-43883 Japanese Utility Model Publication No. 47-2776

As described above, reduction of the trigger load in the spray gun is an important problem to be improved, but there is no structure capable of handling a general spray gun, and the spray gun itself has to be specially manufactured. For this reason, the increase in price has hindered widespread use, and the creation of a spray gun capable of reducing the trigger load using the general-purpose spray gun of the present invention has been cited as an object of the present invention.

More specifically, a general spray gun is used, and a change can be made only by exchanging some parts, and the operability and handling are not changed. The triggering operation is extremely light to reduce the burden on the operator and eliminate factors such as tendonitis.

It is assumed that an appropriate coating film can be formed by reliably maintaining the timing at which the paint valve is opened after the first ejection of air during spraying and preventing spits. It is another object of the present invention to provide a spray gun capable of expanding the application range of painting by improving the operability by controlling the spraying conditions.

The present invention is provided between an outlet passage of an air valve and an atomization cap in order to solve the above-mentioned problem in a spray gun having an air valve operated by a trigger and opening and closing a spray of paint with a needle valve. A branch passage that communicates with the communication passage is taken out of the spray gun through the throttle passage, and a piston that is directly connected to the rear portion of the needle valve of the spray gun and a cylinder that accommodates the piston in a reciprocating manner are disposed at the rear portion of the spray gun. The working air port is provided in the front working air chamber of the cylinder, and one end of the branch passage is connected.

Further, the throttle passage of the branch passage is provided with a flow rate adjusting valve so that the amount of inflow into the cylinder can be adjusted so that the operation of the needle valve can be strictly controlled.
In addition, the branch passage forms an internal passage in the valve shaft of the pattern control valve and communicates with the communication passage. The pattern control valve is connected to the pattern control valve by a rotary joint. It can be an easy spray gun that operates with gold.

When spraying with the above-described configuration, when the air valve is opened by a trigger, the compressed air is ejected from the atomizer through the communication passage. At the same time, air from the communication passage is sent to the air working chamber through the branch passage and the branch passage. At this time, there is a slight delay until the air working chamber is filled with sufficient air through the throttle passage, at least before the atomizing air is injected, the needle valve will not open and the paint will not be ejected. Proper spraying is performed without injecting insufficient atomized particles first, since the atomization air is later than the spraying.

The throttle passage functions to set the timing for the operation of the needle valve, and is set according to the specifications of the spray gun. The size of the flow passage can be selected, but the flow rate can be adjusted, such as a speed control valve. If used, the force applied to the piston can be further controlled, and the setting becomes easy. In addition, by installing this valve, when a malfunction occurs in the piston path, if the flow path is closed, it functions as a normal spray gun and can be dealt with.

In addition, by adjusting the pressure applied to the piston, the pulling amount according to the force of the spring for closing the needle valve can be adjusted, and the opening degree can be adjusted. As a result, the paint ejection amount is adjusted. It is also possible to perform painting work in the state. Therefore, the paint spray amount can be adjusted regardless of the force that activates the trigger to cope with the painting conditions.

In addition, since the air taken out through the valve shaft of the pattern adjustment valve is supplied to the cylinder to take out the air that operates the piston, the pattern adjustment valve can be replaced without changing the spray gun body. The function can be changed and the function can be easily improved by using a general-purpose spray gun.
Therefore, even for users using existing spray guns, the effect of reducing the trigger load can be obtained by simply replacing parts, reducing the burden on workers and preventing future occupational accidents. .

FIG. 3 shows a typical cross-sectional structure of a commonly used general-purpose spray gun. The spray gun body 1 is provided with a paint nozzle 2 and an air cap 3 that constitute an atomizing device at the tip, and a needle valve 4 that engages with the paint nozzle 2 to control the ejection of the paint is provided at the outlet of the paint nozzle 2. It is configured to be actuated by a trigger 5 which will be described later.

An air valve 6, a paint adjusting device 7, and a pattern adjusting device 8 are arranged at the rear of the gun body 1, and a grip 9 is formed at the lower part. A trigger 5 is provided on the front side along the grip 9, and the needle valve 4 and the air valve 5 are operated to control the spraying of the paint and perform painting.

Although there are some differences in configuration, the air valve 6 used for spraying is provided in the air passage 10 to send air introduced from below the grip 9 to the atomizing device, and is pushed by the air valve spring 13. The valve body 12 thus opened is retracted and opened by the operation of the trigger 5 to feed air into the communication passage 11. An air valve spring 13 is disposed at the rear part of the valve body 12 so as to close when the trigger is released. The air valve spring 13 overcomes the back pressure and is provided with a sliding seal for preventing leakage. We need strength that is not affected by dynamic resistance. When the air valve 6 is opened, a force sufficient to overcome the spring load and the back pressure of the compressed air applied to the rear portion of the air valve 6 is required.

Similarly, a needle valve spring 14 is disposed in the rear portion of the gun body 1 in the needle valve 4, and similarly, a spring load sufficient to overcome the back pressure of the paint and the sliding resistance of the needle valve packing is closed. It is necessary. In particular, paint leakage needs to be surely prevented in order to cause serious troubles and defects during painting, the sliding resistance is large, and the needle valve spring 14 is generally set with a high load.

In this embodiment, as shown in FIG. 1, the needle valve 4 penetrates through the central shaft portion of the air valve 6 and is integrated coaxially. According to another example, they may be provided separately, but the present invention is not limited in any way. The load of the air valve spring 13 used in the range of the normal spray gun is about 1 kg at the start of pulling, whereas the load of the needle valve spring 14 is about 2 kg, and is about 3 kg at the maximum load. Actually, the force applied to the finger from the trigger structure is reduced to 1/2 to 1/3 of these, but at the position where the pulling is finished, the load increases due to the deflection of the spring. The sliding resistance of the operator is also high, and the burden on the fingers to be operated for repeated operation is high, and there is a concern about the possibility of causing a failure.

In addition, due to the structure of the spray gun, the opening degree of the needle valve 4 that adjusts the amount of paint sprayed is adjusted by the retreating distance of the needle valve 4, and the adjustment is made by contacting the rear end of the needle valve with the inner end of the adjustment knob 15. It is done by letting. Therefore, the internally mounted needle valve spring 14 has the maximum deflection when the retracting thereof is restricted by the adjustment knob 15. When adjustment of the ejection amount is required, the needle valve spring 14 is set with a high load, and the demand for reducing the trigger load is increased accordingly.

Although the embodiment of the present invention is shown in FIG. 1, a part of the existing spray gun shown in FIG. 3 is modified, and the same functional configuration is indicated by the same symbol as in FIG. A piston 16 is integrally attached to the rear portion of the needle valve 4, and a cylinder 17 in which the piston 16 is accommodated is attached to the gun body 1 with a guide 35 interposed therebetween. The piston rear portion is provided with a piston spring 18 and is accommodated in the cylinder by fixing a lid 19. The working air chamber 28 of the cylinder 17 is provided with a working air port 20 so that the piston 16 is retracted by inflow of air from the outside.

The working air is provided with a joint 22 for taking out by providing a branch passage 21 in the communication passage 11 of the compressed air sent to the atomizer when the air valve 6 is opened, and in the working piston portion provided at the rear portion of the needle valve 4. Configured to be sent.

Needless to say, as in the known spray gun structure, a valve shaft for retreating the air valve 6 in cooperation with the trigger 5 protrudes from the gun body 1 at the tip of the air valve 6. The air valve 6 is opened and ejected as atomizing air from the atomizer. A pattern adjusting valve 23 is provided in the communication passage 11 communicating with the atomizing device as another valve device for controlling spraying, and a knob 24 directly connected to the valve extends to the outside of the gun body 1. Following the opening of the air valve 6, the rear end of the air valve 6 hits the needle valve stop shaft 25, and when the trigger 5 is further pulled, the stop shaft is retracted to open the needle valve 4.

In the case of the present embodiment, a branch path 31 communicating with the outside from the communication path 11 is formed in the shaft of the pattern adjusting valve 23 inherent in the communication path 11, and the branch path connected to the knob 24 by the joint 22. 21 is provided. When the air valve 6 is opened, the air flows from the communication passage 11 to the atomizing device and blows out air, and is sent to the working air chamber 28 through the branch passage 31 and the branch passage 21 to retreat the piston 16. . For this reason, the needle valve 4 moves backward and assists the operation by the trigger 5.

Here, the joint 22 uses a rotary joint that freely rotates with respect to the axis of the knob 24, and the flow rate adjusting device 30 is connected to the joint 22 and connected to the branch passage 21. Accordingly, the knob 24 is freely rotated with the branch passage 21 fixed, and the opening degree of the pattern adjusting valve 23 can be adjusted.

The function of retreating by the piston 16 varies depending on the air pressure, the piston spring 18 against the air pressure, the sliding resistance, etc. If the air pressure is sufficient, the needle valve 4 is opened without the trigger 5 being actuated. The trigger operation is reduced. Therefore, if the operating load of the trigger 5 is reduced, it is only necessary to introduce air corresponding to the trigger 5, the air once introduced into the communication passage 11 is introduced from the branch passage 21, and the throttle port 32 is arranged in the middle. Therefore, the operation of the piston 16 is delayed from the ejection of air, and there is no fear that paint particles that are insufficiently atomized are ejected. In the case of this embodiment, the throttle port 32 is formed in the passage inside the knob 24 of the pattern adjustment valve 23, but is not particularly limited as long as it is between the communication passage 11 and the working air port 20. .

In addition, the size of the cylinder and the piston to be attached may be set to the required operating load from a standard spray pressure or the like generally determined as a spray gun.

By providing a passage branched for the operation of the piston 16 in the communication passage 11 communicating with the atomizing device, the pressure applied to the operating air chamber 28 is not accumulated, and the operation is reduced by a force corresponding to the spray pressure. can do. However, since the operating force applied to the piston changes depending on the spraying condition due to the spray gun, in order to obtain a more accurate and stable operating mitigation force, the inflow amount may be adjusted. In the present embodiment, as one example, the flow rate adjusting device 30 is provided in the introduction path so that the flow rate to be introduced can be adjusted.

Although details of the flow rate adjusting device 30 are omitted, the flow rate adjusting device 30 is generally called a speed controller and is configured to be able to stably supply air at a constant pressure by a device that is commercially available as a flow rate adjusting device for pneumatic equipment. Further, since the inflow amount can be accurately controlled, the retraction amount of the needle valve 4 can be controlled if the balance between the operation of the piston 16 and the spring force of the rear portion is maintained, and the opening of the needle valve can be stopped at an intermediate adjustment position. Therefore, it can also be used as a spray gun capable of adjusting the ejection amount.

FIG. 2 partially shows another embodiment of the present invention, which is different from FIG. 1 in the configuration of the air piston 41 at the rear portion of the needle valve. In this embodiment, a part of a spray gun used for general purposes is changed so that the effect of the present invention can be obtained more easily than in FIG. A small-diameter piston 41 is provided on the stop shaft 40 of the needle valve 4, a working air chamber 43 and a packing chamber 44 are formed in a cylinder 42 that accommodates the piston 41, and an adjustment knob 45 is screwed in the rear part to position the rear end of the needle valve It becomes the composition which regulates. Air from the introduction path 47 attached to the outside is sent to the working air chamber 43 through the introduction port 46.

In operation, as in the case of FIG. 1 described above, a part of the atomized air is sent from the introduction path to the air working chamber by the trigger, and works in the direction in which the piston 41 moves backward. In this case, when the pressure receiving area of the piston is not sufficient, if the blowing pressure is low, sufficient operating force cannot be obtained to open the needle valve, but the trigger operating load is reduced and effectiveness for the operator is maintained. Is done.

FIG. 1 is a cross-sectional view showing an embodiment of the present invention. FIG. 2 is a sectional view showing a part of another embodiment of the present invention. FIG. 3 is a sectional view of a conventional general spray gun.

Explanation of symbols

1. Gun body 2, paint nozzle 4, needle valve 5, trigger 6, air valve 7, paint adjusting device
8. Pattern adjustment device
9, grip 10, air passage 11, communication passage 12, valve body 13, air valve spring 14, needle valve springs 15 and 45, adjustment knobs 16 and 41, pistons 17 and 42, cylinder 18, lids 19 and 43, operation Air chamber 20, operating air port 21, branch passages 22 and 26, joint 23, pattern adjusting valve 24, knob 25, needle valve stop shaft 28, operating air chamber 30, flow rate adjusting device 31, branch path 32, throttle port 44, Packing chamber 46, introduction port 47, introduction path

Claims (3)

In a spray gun provided with an air valve operated by a trigger and a needle valve that opens and closes a paint outlet, a branch passage communicating with a communication passage provided between the outlet passage of the air valve and the atomizing device, A cylinder that is taken out of the spray gun through the throttle passage and accommodates a piston that is directly connected to the rear part of the needle valve so as to be able to reciprocate is connected to the rear part of the spray gun, and operating air is supplied into the front working air chamber of the cylinder. A spray gun for coating, wherein the spray valve is provided and connected to one end of the branch passage, and the needle valve is actuated by a trigger . 2. The spray gun for painting according to claim 1, wherein the throttle passage of the branch passage is provided with a flow rate adjusting valve capable of adjusting an inflow amount into the cylinder. 2. The spray gun for painting according to claim 1, wherein the branch passage forms an internal passage in the valve shaft of the pattern control valve to communicate with the communication passage, and is connected to the pattern control valve by a rotatable joint.

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