JP3686892B2 - Gun for powder electrostatic coating - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an effective arrangement of a charging electrode and a grounding portion of an electrostatic powder coating gun for charging a powder coating material by corona discharge from a high voltage power source and effectively applying the powder coating material.
[0002]
[Prior art]
For electrostatic coating guns, a system is often used in which a corona discharge electrode is arranged at the tip of a paint jet, and an ionization region is formed by discharge to charge spray particles. The lines of electric force from the tip electrode when a high voltage is applied are directed to the grounded object, an electric field is formed between the tip of the gun and the object to be painted, and a grounded operation unit located at the rear of the gun. Also discharged.
[0003]
Normally, the handle that constitutes the operation unit is placed on the ground side, and the discharge from the tip electrode becomes stronger as the distance is shorter, the discharge current flowing to the handle side increases, and the discharge to the object to be coated decreases. The effect of applying static electricity is reduced. Accordingly, it is necessary to eliminate unnecessary discharge to the discharge electrode and the grounding side of the rear part, and to secure a necessary distance in order to concentrate on the object to be coated, and as a result, the barrel part constituted by the insulating member is lengthened.
[0004]
In addition, when the insulation distance from the electrode to the finger on the ground side is short for the worker to use, there is a high risk of accidental electric shock to the worker due to creeping discharge, and there is a problem in terms of safety.
Conversely, if the electrode is moved away from the handle side and the distance between the object to be painted and the electrode is reduced, the electric field concentration due to corona discharge is applied to the painted surface of the object to be painted, especially the edge where the electric field tends to concentrate. Since problems such as coating concentration occur, a ground electrode is provided at the rear of the discharge electrode as a means to improve the finished quality, and the strength of the electric field of the corona discharge formed toward the object to be coated is adjusted. Things have been done. However, even in this case, the discharge state to the ground electrode is adjusted by the distance from the electrode, and the danger to the discharge to the worker is not avoided. Therefore, if it is an automatic operation type gun that is not operated by the operator directly in terms of safety, even if it is configured with a long barrel and sufficiently maintained insulation distance, it is less affected by operability In addition, it is proposed that the effect is exhibited.
[0005]
However, in general, increasing the length of the barrel will increase the size and weight of the gun, which will greatly reduce the operability of the gun, and especially in the case of a manually operated gun, it will extend forward with respect to the handle. Therefore, the influence is extremely large for those who continue daily work.
[0006]
[Problems to be solved by the invention]
The present invention provides a tip electrode for ensuring the safety of an operator when an attempt is made to obtain a handgun for powder electrostatic coating with a shortened barrel portion to improve operability. It is intended to suppress the discharge from and prevent accidental electric shock to the worker and to obtain an appropriate electrostatic effect to improve the coating efficiency.
[0007]
[Means for solving problems]
A powder electrostatic coating gun in which a corona electrode for charging spray particles is arranged at the tip of a barrel made of an insulating material, and at least a part of the barrel is made of a conductive material and a handle at ground potential is arranged In contrast, by gripping the handle on the rear ground side from the corona electrode by shortening the distance between the barrel portion, that is, the electrode and the rear conductive portion, and placing a semiconductive member connected to the ground side therebetween Accordingly, it is possible to suppress the discharge to the finger of the worker who is on the same ground side and to improve the safety. In addition, the high voltage applied to the electrode can be stably maintained by suppressing the discharge to the rear part, and the charging effect and the electrostatic field are maintained to ensure the electrostatic coating efficiency and the stability of the coating quality. It is something that can be done.
[0008]
The handle is made of a conductive material or a semiconductive material, and is a member operated by a worker connected to the ground side, and the electric shock prevention member is a ring-shaped member surrounding the barrel of the insulating material. The discharge from the corona electrode is reliably received, and the discharge to the ground-side worker in the rear part is suppressed. This ring-shaped member is connected to the ground potential side with a handle via a connection means of a semiconductive material disposed in the barrel.
[0009]
Furthermore, the semiconductive ring-shaped member is configured to be detachably fitted to the barrel portion, and means for constantly pressing a part of the ring-shaped member with an elastic member when fitted to the connection portion on the ground side. By providing, it is configured so that connection can be made reliably.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
The powder coating gun shown in FIG. 1 shows one embodiment of the present invention, and is a spray having a jet port 3 at the tip of a barrel part 2 formed of an insulating material extending at the tip of the gun body 1. Means and an electrode 5 to which a high voltage is applied are provided. The lower part of the gun body 1 has a handle 10, and a trigger 11 is provided on a part thereof.
[0011]
The internal structure usually has a powder inlet 12 at the bottom of the handle 10, and the powder coating introduced together with the compressed air is formed in the electrode nozzle 6 at the tip through a powder passage 4 connected to the barrel part 2. It sprays from the jet nozzle 3. In the case of the embodiment, a flat blow nozzle 7 is fitted at the tip of the jet nozzle 3 so that the powder is sprayed on the object to be coated with a flat spray width.
[0012]
On the other hand, the high voltage that charges the powder and forms an electrostatic field is sent to the high-voltage cartridge 14 of the gun body 1 from the cable connection terminal 8 similarly provided at the lower part of the handle 10, where it is boosted to a predetermined high voltage. . The high-voltage output terminal is connected to the charged electrode in the electrode nozzle 6 through a conductive member, charges the powder paint sprayed through this, and discharges from the tip electrode 5 to form an electric field toward the object to be coated. To do.
[0013]
Further, since these powder ejection and high-voltage charging are performed by a switching operation performed by the trigger 11, a connector 8 is provided for signal input / output with a control device (not shown). Usually, several examples of these configurations as a powder gun for electrostatic coating have already been practically used.
[0014]
The periphery of the electrode nozzle 6 protruding through the tip body of the gun body 1 is surrounded by an insulating cover 9, and a flat blow nozzle 7 provided with a wide opening so as to cover the outside of the tip of the jet nozzle 3 of the electrode nozzle 6. Is inserted.
The electrode 5 located at the tip of the ejection port 3 is pin-shaped to concentrate the electric field, and the ionization region and electric field are formed in an optimum state by discharge.
[0015]
In the embodiment of FIG. 1 according to the present invention, the rear handle 10 is electrically grounded as a conductive material, and when the operator grips it with his hand, the finger on the trigger 11 is on the ground side, A high potential difference is formed between them. This type of electrostatic gun is used for the distance necessary to prevent creeping discharge from the normal electrode, eliminate the electric shock to the worker, maintain the voltage of the tip electrode 5 and maintain the electric field to the object to be coated. When the tip voltage is −85 kV, it is about 180 mm behind the tip electrode 5, and when the tip voltage is −65 kV, it is about 160 mm.
[0016]
Between the tip of the high-voltage electrode 5 and the handle 10 on the ground side, an earth ring 18 made of a thin ring-shaped semiconductive member is provided. As shown in FIG. 2, the electrical connection of the earth ring 18 is provided with a terminal 16 projecting from the body 15 so as to contact the inner surface of the earth ring 18, and this terminal 16 is always pressed by a spring 17 that repels from the inside. ing. The terminal 16 is electrically connected to the handle 10 on the ground side through a spring 17 and a connection member 19 made of a semiconductive material, with a connection piece 20 shown in FIG.
The earth ring 18 is fitted in a groove 2A provided in the barrel part 2 so as to be detachable. However, the earth ring 18 is arranged around the barrel part at an equal distance from the electrode 5 and is connected to the ground potential side. Any configuration may be used as long as the members are arranged. In the case of the present embodiment, the earth ring 18 is located about 95 mm behind the tip electrode.
[0017]
The distance from the electrode 5 to the trigger 11 is about 145 mm, which is significantly shortened compared to the conventional case. The resistivity of the semiconductive material of the earth ring 18 and the connecting member 19 is selected according to various conditions such as charging voltage, electrode shape and arrangement thereof, an object to be painted at the time of painting, or a surrounding object placed at the ground potential. However, generally, 10 <2> to 10 <10> [Omega] cm, preferably 10 <4> to 10 <8> [Omega] cm is used.
[0018]
As a result, a part of the discharge from the tip charged electrode is led to the earth ring in a suppressed state, and the danger of sudden discharge to the worker can be prevented. In addition, since a stable corona discharge is maintained when an appropriate discharge current always flows through the earth ring, the charged particles are stably charged by the corona discharge without being affected by a change in the distance to the object to be coated. Furthermore, electrostatic coating can be stabilized without abrupt changes in the electric field applied to the object to be coated, and the coating film quality can be stabilized.
[0019]
【The invention's effect】
As described above, according to the present invention, the barrel portion can be shortened as compared with the prior art, and the effect of the reduction in size and weight can significantly improve the operability for the user and reduce the work load. In particular, when the operator holds it in his / her hand, a force more than a mere mass acts due to the moment applied to the tip, so a slight shortening of the barrel portion has a great influence and brings a great effect.
[0020]
By improving the operability by shortening the distance between the tip electrode position and the handle, and further improving the coating efficiency without causing a risk of high voltage discharge, the present invention Adoption of this can not only improve productivity but also improve coating quality, and the effect is extremely great.
[Brief description of the drawings]
FIG. 1 is a sectional view of a powder electrostatic coating gun according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view of a ground ring mounting portion connected to a ground potential by a semiconductive material. Perspective view showing only the general connection [Explanation of symbols]
1, gun body 2, barrel part 3, jet nozzle 4, powder passage 5, electrode 6, electrode nozzle 10, handle 11, trigger 15, barrel 16, terminal 18, ground member 19, connection member

Claims (4)

Powder electrostatics in which a corona electrode for charging spray particles is arranged at the tip of a barrel made of an insulating material, and at least a part of the rear part of the barrel is electrically conductive and a handle connected to the ground side In the coating gun, an electrostatic powder coating is provided between the electrode and the rear conductive handle, and is provided with a shock preventing member made of a semiconductive member and grounded on the handle side on the barrel portion. Gun for. The powder electrostatic coating gun according to claim 1, wherein an electric shock preventing member is disposed around the barrel, is electrically connected to the grounded handle, and is manually operated with the handle. 2. The powder electrostatic coating gun according to claim 1, wherein the electric shock preventing member is electrically connected to the ground side by connection means provided in a barrel of an insulating material. 4. The electrostatic powder coating for powder electrostatic coating according to claim 2 and 3, wherein means for constantly pressing the ring-shaped member with an elastic material is provided in the connecting portion when the electric shock preventing member is detachably fitted to the barrel portion. gun.

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