JP2011177706A - Powder coating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a powder coating apparatus capable of coating in every hole and corner with an enough film thickness even on the rugged shaped article to be coated or the article to be coated which is formed by a thin wire such as a net fence and excellent in use efficiency of the powder coating. <P>SOLUTION: A powder coating apparatus includes a powder coating tank 21 where the powder coating charged by frictional electrification is stored, having a fluid layer of powder coating 21a at the lower part and an atomized layer of powder coating 21b at the upper part. The powder coating charged by frictional electrification is adhered to an article to be coated 20 by immersing or passing the grounded article to be coated 20 at least in the fluid layer 21a or the atomized layer 21b of the powder coating tank. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a powder coating apparatus that can be applied with high efficiency without spraying a powder coating onto an object to be coated.

  Powder coating does not contain organic solvents, and overspray powder that has not adhered to the object to be coated can be collected and reused, so it has been adopted in many products in recent years as an environmentally friendly coating.

  It started with road materials such as guardrails and fences, and is widely used in products used at home such as refrigerators and air conditioner outdoor units. Recently, it is also used to paint school chairs and desks and license plates.

  In general, powder coating is performed by using a corona gun or a frictional charging gun and spraying a powder coating on an object to be coated.

  In the case of a corona gun, an electric field is generated between the corona electrode at the tip of the gun and the object to be coated, and the powder paint discharged from the gun is attached to the object by corona discharge.

  In addition, the friction charging gun includes a non-conductive resin tube, for example, in the gun, and the powder paint is passed through the non-conductive resin tube to cause friction between the non-conductive resin and the powder paint. Thus, the charged powder coating discharged from the gun tip adheres to the object to be coated by electrostatic force.

  Of course, as shown in FIG. 27, both of the above two methods discharge the powder coating 3 from the coating gun 1 toward the object 2 by forced air such as compressor air, for example. Overspray powder that does not adhere to the surface is generated. For this reason, the painting operation is performed in the painting booth 4, and overspray powder that does not adhere to the workpiece 2 is sucked and collected from the suction port 5 provided in the painting booth 4. The overspray powder collected by suction is reused after passing through a screening device.

  However, the paint particle size distribution of the recovered powder is greatly different from that of the new powder, and the number of paints that are difficult to adhere to the article 2 is increased. For this reason, a problem remains with respect to the object 2 to be coated, and a large number of painting guns are required to paint.

  On the other hand, there is an electrostatic fluidized immersion device as a powder coating device that does not depend on spraying from a coating gun.

  As shown in FIG. 28, the electrostatic fluid immersion apparatus is provided with a corona electrode 8 to which a high voltage is applied by a high voltage generator 7 in a powder coating tank 6 containing a powder coating, and is generated by the corona electrode 8. This is an apparatus for adhering the powder coating to the object to be coated 2 passing through the powder coating tank 6 by an electric field.

  The powder coating tank 6 of this electrostatic fluid immersion apparatus is partitioned at the bottom by a porous material 9 such as a porous resin or a campus cloth, and the fluidized air 10 is supplied to the lower part of the porous material 9, The powder coating inside is made to flow as if it were a liquid.

  The corona electrode 8 is installed on the porous material 9 or inside or on the lower surface of the porous material 9 in order to prevent the electrode from being contaminated, and forms an electric field between the corona electrode 8 and the article 2 to be coated. I am doing so.

  In this case, the inside of the powder coating tank 6 includes a portion of the fluidized bed 11 in which the powder coating is flowing as if it were a liquid, and an atomized layer 12 that is atomized (clouded) above the fluidized bed 11. Part is formed. Even if the article 2 is dipped in the fluidized bed 11 where the powder paint is flowing like a liquid, the powder paint does not adhere to the article 2 but is in the vicinity of the porous material 9. The powder paint that is atomized (clouded) in the portion of the atomized layer 12 by the electric field from the corona electrode 8 adheres to the object to be coated 2.

  An example of such a coating method is also disclosed in Non-Patent Document 1. In Non-Patent Document 1, for example, about 2/3 of an object to be coated is immersed in a fluidized powder paint, and 1/3 is coated in an atomized layer (cloud), and the object to be coated is gradually raised. Thus, the remaining portion is sufficiently coated by passing through the atomized layer (cloud).

  As described above, even if the article 2 is immersed in the fluidized bed 11, the powder paint 2 does not adhere to the article 2 because the fluidized bed 11 flows like a liquid. This is considered to be because the air in the fluidized bed 11 is dilute and an electric field cannot be generated.

  In the electrostatic fluidized immersion apparatus in which the corona electrode 8 is installed in the powder coating tank 6, since the coating is performed only with the atomized layer 12 above the fluidized bed 11, the size of the object to be coated 2 is limited. . The first reason is that the height of the portion of the atomized layer 12 is low, and generally it can be applied only to the article 2 to be coated of about 100 mm. The second reason is that if the distance between the corona electrode 8 and the object to be coated 2 is increased, an electric field is not formed. Therefore, the distance between the object to be coated 2 and the corona electrode 8 is generally about 250 mm. Yes.

  Therefore, in the electrostatic fluidized immersion apparatus in which the corona electrode 8 is installed in the powder coating tank 6, the object to be coated 2 is limited to a small one such as a micromotor as shown in FIG. For this reason, generally, the mist formed on the fluidized bed 11 without immersing the workpiece 2 in the fluidized bed 11 in which the powder coating is flowing like a liquid. The present condition is that the coating which adheres the powder coating material of the atomization layer 12 to the to-be-coated article 2 is performed by letting the formation layer 12 pass.

  Further, in the electrostatic fluidizing immersion apparatus in which the corona electrode 8 is installed in the powder coating tank 6, the material of the powder coating tank 6 is limited to an insulating material. That is, if the material of the powder coating tank 6 is conductive, for example, metal, all the electrons discharged from the corona electrode 8 are discharged to the (metal) material of the nearby powder coating tank 6 and covered. An electric field cannot be formed between the object to be coated 2 and the powder paint cannot be adhered to the object to be coated 2.

  Further, when the distance from the porous material 9 on which the corona electrode 8 is installed to the object to be coated 2 is increased, that is, when the distance from the corona electrode 8 is increased, the powder paint is floating between the object 2 The electric field is weakened and the powder coating is difficult to adhere.

In addition, there is a fluid immersion method that does not use static electricity as another painting method, and it is often used for painting bicycle bicycles, net fences, and the like.
In this method, as shown in FIG. 29, a preheating furnace 14, a fluid tank 15 for storing powder coating material in a fluidized state, and a baking / drying furnace 16 are installed along a line 13 for conveying the object 2 to be preheated. After preheating the object 2 to be coated at a temperature of about 270 ° C. in the furnace 14, the object 2 is moved above the fluid tank 15 that can be moved up and down, and the fluid tank 15 is raised to cover the fluid tank 15. This is a method in which the powder paint is melted and adhered to the surface of the article to be coated 2 by immersing the article to be coated 2. Thereafter, the fluidized tank 15 is lowered to take out the object 2 to be coated, supplied to the baking / drying furnace 16, and reheated at a temperature of about 200 ° C. to apply the paint adhering to the surface of the object 2 to be coated. Smooth the skin. Thereafter, unloading is performed from the line 13.

  In this preheating dipping method, the film thickness is as large as 400 μm or more. Also, the powder coating that can be used is limited to thermoplastic resins such as vinyl chloride and polyethylene, and epoxy and polyester powder coatings cannot generally be used. In addition, the powder coating tends to sag due to the immersion after preheating.

Published by Cortec Co., Ltd. “Electrostatic powder coating” by J. F. Hughes, pp. 60-65

  As described above, the conventional electrostatic coating method, in which powder coating is applied to an object to be coated, is not made of a thin wire such as an object to be coated with unevenness or a net fence. If there is a place where the powder paint is hard to hit, the part is likely to be poorly painted.

  In addition, since many of the discharged paints become overspray powder, there is a problem that the coating efficiency is poor.

  On the other hand, the coating method using an electrostatic fluidized immersion device in which a corona electrode is installed in a fluid tank containing powder coating has a longer retention time of powder coating around the object to be coated than gun coating, but the powder Since the paint does not always stay there, it is difficult to enter the uneven portions that are particularly difficult to paint. Further, it is difficult for the electric field of the corona electrode to reach the concave portion of the object to be coated, and it is difficult to keep the powder coating around the concave portion.

  The fluidized dip coating method in which the object to be coated is preheated is efficient in using the powder paint, but has a problem that the object to be coated needs to be preheated and becomes a thick film. There is also a problem that the powder coating that can be used is limited.

  In view of this, the present invention is a coating method performed by discharging a powder paint, and is an object to be coated formed of a thin wire material such as a concave-convex shaped object or a net fence in which a portion that is the shadow of discharge is formed. However, it is an object of the present invention to provide a powder coating apparatus that can be applied to every corner with a sufficient film thickness and that has good use efficiency of the powder paint.

  In order to solve the above-described problems, a powder coating apparatus according to the present invention contains a powder paint charged with frictional charging, a fluidized layer of powder paint at the bottom, and atomization of the powder paint at the top A powder coating tank having a layer, and the object to be coated is frictionally charged by immersing or passing the grounded coating object in at least one of the fluidized layer or the atomizing layer of the powder coating tank. It is characterized by adhering paint.

  The powder coating tank may be mixed with a powder coating that is not charged.

  As a means for imparting electric charge to the powder paint contained in the powder paint tank, a friction charging device made of a non-conductive resin to be brought into contact with the powder paint can be used in addition to a general tribogun called tribogun. it can.

  A hollow portion through which an object to be coated with the frictionally charged powder coating passes may be installed in the powder coating tank, and the amount of the powder coating applied may be adjusted by the hollow portion.

  The powder coating tank may be made of a nonconductive resin or a conductive material such as metal or conductive resin.

  As described above, the powder coating apparatus according to the present invention has the powder coating tank for storing the powder coating that has been charged by frictional charging, so that the grounded object can be used as the fluidized bed of the powder coating tank. Simply by dipping or bringing it closer to the atomized layer, the charged powder coating is adsorbed to the object to be coated.

  Therefore, even for uneven objects and objects to be coated that are formed from thin wires such as net fences, powder paint is adsorbed with a sufficient film thickness to every corner, and does not adhere by spray coating. Since the fine powder coating can be adhered to the object to be coated without waste, the use efficiency of the powder coating is very good.

1 is a schematic longitudinal sectional front view showing a first embodiment of the present invention. 1 is a perspective view of a first embodiment of the present invention. 1 is a schematic vertical plan view showing a first embodiment of the present invention. It is a schematic block diagram which shows the path | route which removes dust and makes it return to a powder coating material tank, frictionally charging the powder coating material in a fluidized bed. It is a perspective view which shows the to-be-painted object of 2nd Example of this invention. It is a schematic longitudinal front view which shows the 2nd Example of this invention. It is a general | schematic longitudinal cross-sectional side view which shows 2nd Example of this invention. It is a schematic longitudinal cross-sectional front view which shows the 3rd Example of this invention. It is a general | schematic longitudinal side view which shows the 3rd Example of this invention. It is a schematic longitudinal cross-sectional front view which shows the 4th Example of this invention. It is a schematic longitudinal cross-sectional top view which shows the 4th Example of this invention. It is a schematic block diagram which shows an example of friction charging. It is a schematic block diagram which shows the other example of friction charging. It is a schematic longitudinal cross-sectional front view which shows the 5th Example of this invention. It is a general | schematic longitudinal section side view which shows the 5th Example of this invention. It is a general | schematic longitudinal section top view which shows the 5th Example of this invention. It is a perspective view which shows the to-be-painted object of 6th Example of this invention. It is a schematic longitudinal front view which shows the 6th Example of this invention. It is a cross-sectional view which shows the powder coating tank of 6th Example of this invention. (A) (b) is a fragmentary sectional view which shows the gun | tip tip nozzle which can be used for the 6th Example of this invention. It is a schematic longitudinal front view which shows the 7th Example of this invention. It is a fragmentary sectional view which shows the gun | tip tip nozzle which can be used for the 7th Example of this invention. It is a perspective view which shows the to-be-coated object of the 8th Example of this invention. It is a schematic longitudinal front view which shows the 8th Example of this invention. It is a schematic longitudinal cross-sectional front view which shows the modification of the 8th Example of this invention. It is a schematic longitudinal cross-sectional front view which shows the modification of the 8th Example of this invention. It is the schematic of the conventional electrostatic coating apparatus. It is the schematic of the conventional electrostatic fluid immersion apparatus. It is the schematic of the conventional preheating immersion apparatus.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
1 to 3 show a first embodiment of the present invention for coating an object to be coated 20 in which thin wires such as a net fence are joined together.

  As shown in FIG. 1, the powder coating apparatus according to the first embodiment has a powder coating tank 21 in which a powder coating to which electric charges are given by frictional charging is accommodated. A fluidized layer 21a in which the powder paint is in a liquid state is formed in the lower portion by the fluidized air 24 from above, and an atomized layer 21b in which the powder paint drifts in the atomized state is formed in the upper portion.

  The object to be coated 20 is suspended from a hanger 22 that moves up and down, and can be taken in and out of the powder coating tank 21. The object to be coated 20 is grounded.

  The powder coating tank 21 is partitioned at the bottom by a porous material 23, fluidized air 24 is supplied to the lower surface side of the porous material 23, the powdered paint in the tank flows by the fluidized air 24, and the powder at the bottom. A fluidized layer 21a of paint is formed, and an atomized layer 21b of powder paint is formed on the top.

  In the case of the first embodiment, a thermosetting polyester-based one is used as the powder coating material stored in the powder coating tank 21. As the powder coating material, powder coating materials of four colors other than white are prepared.

  As shown in FIG. 3, a total of eight friction charging guns 25 are installed on the side surface of the powder coating tank 21 in order to give a frictional charge to the powder coating material to be accommodated. The frictional charging gun 25 has a gun tip nozzle branched into a large number and is disposed along the side surface of the powder coating material tank 21.

  The tip of the gun tip nozzle of the friction charging gun 25 is arranged so that the tip of the tip of the gun tip nozzle does not hit the gun tip nozzle even if the suspended article 20 is swung in the powder paint bath 21. It does not protrude inside. Even if the tip of the gun tip nozzle protrudes into the powder coating tank 21, the gun tip nozzle of the frictional charging gun 25 does not have an electrode like a corona gun. . Therefore, the tip of the gun may protrude into the powder coating tank 21. However, if the tip of the gun tip nozzle does not protrude into the powder coating tank 21 as shown in FIG. 3, the workability at the time of cleaning the powder coating tank 21 is good.

  Since the powder coating tank 21 is not a corona charging system, the upper part is opened, and the excess atomized powder of the atomized layer 21b formed on the upper part of the fluidized bed 21a flows out slightly. Therefore, a dust collector is installed around the powder coating tank 21 and the excess atomized powder that has flowed out is sucked. However, in a general electrostatic coating apparatus that sprays powder coating from a coating gun to an object to be coated, As shown in FIG. 27, there is much dust scattering, which is surrounded by the coating booth 4 and the dust collector becomes large. However, in this invention, there is little surplus atomized powder flowing out, so a large dust collector is not necessary.

  In the present invention, the powder coating material is not sprayed on the object to be coated 20 but is charged from the frictional charging gun 25 into the powder coating material tank 21 so that the charged powder coating material is stored in the powder coating material tank 21. Since the body paint is supplied, the spray diffusion due to the discharge air from the frictional charging gun 25 can be suppressed. Therefore, the dust collector only sucks the fluid surplus powder paint in the upper part of the powder paint tank 21.

  In the embodiment of FIGS. 1 to 3, three objects 20 are suspended, and as shown in FIG. 1, the atomized layer 21 b is passed from the upper part of the powder coating tank 21 to enter the fluidized bed 21 a. Soak slowly. The stop time in the fluidized bed 21a of the powder coating tank 21 is about 2 seconds.

  In the powder coating tank 21, powder coating that has not been frictionally charged from the beginning is also flowing. Even if the net fence that is the article to be coated 20 is immersed in the powder paint that is not frictionally charged, the powder paint does not adhere to the net fence as a matter of course.

  However, in the present invention, when a powder paint that is frictionally charged at 150 g / min, for example, is supplied from each friction charging gun 25 to the powder paint tank 21, the frictionally charged powder paint is contained in the powder paint tank 21. So, it is mixed with powder paint that has not been rubbed from the beginning. Thereby, when the net fence which is the article to be coated 20 is brought close to the inside of the powder coating tank 21, the powder paint of the atomized layer 21 b in the atomized state above the fluidized bed 21 a is applied to the article to be coated 20. To start attachment. The atomized powder paint contains a large amount of particularly fine powder of the paint particles in the powder paint tank 21. This fine powder is floating above the powder coating material of the fluidized fluidized bed 21a and is not forcedly sprayed by air as in the case of a coating gun, so the coating efficiency of the fine powder is also good. The film thickness of the atomized layer 21b above the fluidized bed 21a in the fluidized state is 40 to 60 μm. The uniformity of the film thickness is also good, and the film thickness is not affected by the arrangement of the electrodes as in the conventional electrostatic fluid immersion with corona electrodes installed inside. This is because the powder coating particles themselves are charged, and the floating powder coating adheres to the object to be coated 20 at any location.

  After that, when the net fence that is the object to be coated 20 is gradually immersed in the fluidized fluidized bed 21a, the mixed powder coating starts to adhere suddenly toward the object to be coated 20 like a magnet. To do.

  In the coating of the net fence as in the first embodiment, the film thickness regulation is 200 μm or more. In particular, the attachment of the cross part (welded part) of the wire material is emphasized, but since there is no blow-off (gap air) by forced air like a coating gun, a sufficient thick film coating can be performed in the present invention. For this reason, no pinhole is seen in the cross portion of the wire. Also, it adheres more than the amount of powder paint discharged from the paint gun.

  In the first embodiment, as described above, the powder coating material is charged from the frictional charging gun 25 into the powder coating tank 21 at a rate of 150 g / min per gun and a total of 1200 g / min with 8 guns. Was supplied to the powder coating tank 21.

When the coating time is 40 seconds, the powder coating tank 21 has
1200 × 40 ÷ 60 = 800g / 40sec
It is calculated that the charged powder coating is supplied.

In the first example, when the amount of powder coating on the three net fences to be coated 20 was measured, a total of 1830 g of powder coating was adhered.
This adhesion amount is larger than the supply amount of the charged powder coating material.
That is, the ratio (adhesion efficiency) of the adhesion amount to the discharge amount from the frictional charging gun 25 is:
1880 ÷ 800 × 100 (%) = 235%
It is.

  This is presumably because the powder coating that was originally present in the powder coating tank 21 was pseudo-charged by the supply of the frictionally charged powder coating and adhered to the net fence as the object to be coated 20. .

  Therefore, it is preferable to store the powder coating material that is not frictionally charged in the powder coating material tank 21.

  The adhesion of the pseudo-charged powder coating feels weaker than the powder coating charged with frictional charging.

  The desired film thickness of the net fence which is the article to be coated 20 in the first embodiment is 200 μm or more, but the film thickness after the coating is 350 μm or more.

  For this reason, when a vibration was applied to the hanger 22 of the net fence that is the object to be coated 20, the powder coating material with weak adhesion dropped into the powder coating material tank 21.

  When the film thickness after the powder paint having a weak adhesive force was dropped by vibration was measured, a film thickness of 220 μm and a uniform film thickness was obtained.

  The film thickness can be adjusted by the discharge amount, current value, immersion time, particle size distribution of the paint, the vibration intensity of the hanger 22 that suspends the article to be coated 20, and the number of times.

  Since the powder paint in the powder paint tank 21 gradually decreases as the object 20 is applied, the powder paint is automatically replenished so as to maintain the volume of the fluidized bed 21a.

  In addition, since the powder paint in the powder paint tank 21 is mixed with dust as the coating progresses, a powder paint circulation path 26 in the powder paint tank 21 is provided as shown in FIG. It is desirable to install a vibrating screen 27 in the circulation path 26 to remove dust.

  In the above embodiment, stainless steel is used as the material for the powder coating tank 21, but it may be formed of a conductive resin. The powder coating tank 21 is grounded, and the total charge of the powder coating tank 21 can be reduced by forming it with a conductive material.

  Further, even if the powder coating tank 21 is made of an insulating material, for example, a vinyl chloride tank, as in the case of the conventional electrostatic fluid immersion apparatus, there is no difference in the amount of attachment and the amount of attachment.

  In the first embodiment, the object to be coated 20 is a net fence, and is a product that is easy to paint in shape. The gun tip and the object to be painted are prevented from protruding into the powder coating tank 21. Although contact with the object 20 is prevented, for example, in the case of a product having a complicated welded part such as a two-wheeled vehicle or buggy, the gun tip is protruded into the powder coating tank 21, and the gun tip is You may make it enter into the clearance gap between the articles 20 to be coated. Even if the gun tip comes into contact with the object to be coated 20 by protruding the gun tip into the powder coating tank 21, there is no problem because no electrode like a corona gun exists at the tip of the gun tip. In addition, the point of contact with the gun tip becomes a defective product as a scratch on the coating film in the case of general painting, but in the case of this invention, even if the gun tip touches and scratches, Since the powder paint adheres to the scratched area, the scratch is eliminated.

  When a plurality of objects to be coated 20 are dipped in the powder coating tank 21 to perform coating, if there are few gaps between adjacent objects to be coated 20 and the powder coating is poorly attached, You may make it install the jig | tool which opens the clearance gap between the adjacent to-be-coated objects 20 in the body coating tank 21 during coating. If the jig is removed after the gap is painted at the contact portion between the workpiece 20 and the jig, the powder paint immediately adheres, and the scratch caused by the jig is repaired.

Next, a second embodiment of the present invention will be described with reference to FIGS.
In the second embodiment, the object to be coated 20 is a net-like pallet container as shown in FIG.

  The net-like pallet container can be folded, and coating is performed in a folded state as shown in FIGS.

  The pallet container to be painted in the second embodiment has dimensions of 1100 mm (L) × 900 mm (H) × 250 mm (W) when folded.

  Further, the powder coating tank 21 used in the second embodiment is 1500 mm (L) × 1200 mm (H) × 900 mm (W), and a partition of a porous material 23 of 20 mm is installed at the bottom. As the porous material 23, three layers of campus cloth were used.

  The material of the powder coating tank 21 of the second embodiment is vinyl chloride resin. As shown in FIG. 7, an outlet 28 through which a part of the atomized layer 21 b flows out is installed on the side surface 200 mm from the upper surface of the powder coating tank 21, and a receiving tank 29 is installed outside the outlet 28. The powder coating material accumulated in the receiving tank 29 can be supplied to the frictional charging gun 25 by the injector 29a.

  A friction charging gun 25 is installed in the powder coating tank 21 in order to supply powder coating charged by friction charging.

  The frictional charging gun 25 is not fixed to the side surface of the powder coating tank 21, but as shown in FIGS. 6 and 7, the inside of the powder coating tank 21 is caused by the reciprocator 30 from the upper surface of the powder coating tank 21. It is installed so that it can move up and down (up and down) left and right.

  The tip of the triboelectric gun 25 is branched into, for example, 24, and the branch pitch is 25 mm, and one gun is arranged in parallel on one side, with the object to be coated 20 as the center.

  Similar to the first embodiment, the article 20 is moved by being hanged by a conveyor 31 with a drop lifter, and the conveyor 31 stops above the powder coating tank 21. The article 20 to be coated is lowered into the powder coating tank 21 from the stopped conveyor 31 and stopped at a fixed position. At the same time, the reciprocator 30 in which the frictional charging gun 25 is installed drives left and right while moving up and down the inner surface of the powder coating tank 21.

  In this second embodiment, in order to reduce the number of friction charging guns 25 and obtain uniform coverage, the powder coating material charged uniformly by frictional charging is uniformly distributed in the powder coating material tank 21. The powder paint in the powder paint tank 21 is diffused by the movement of the gun so as to be dispersed.

  Simultaneously with the operation of the reciprocator 30, each frictional charging gun 25 discharges 200 g / min of powder coating material from a quantitative supply device installed at the entrance of the powder coating material hose. The discharge time is set to 20 seconds per cycle, and after the painting is finished, the frictional charging gun 25 returns to the standby position above the powder coating material tank 21. Thereafter, the pallet container that is the object to be coated 20 ascends above the powder coating tank 21.

  As described above, in the second embodiment, although the pallet container that is the object to be coated 20 is coated in a folded state, sufficient coating is applied to the combination part of the wire rods and the cross welded portion. I was able to. This is presumably because the powder paint that was frictionally charged stays around the object 20 to be coated. Powder coating is deposited on the upper surface of some wire rods, resulting in over-spec coating. For this reason, after raising the article to be coated 20, if vibration is applied to the hanger 22 that suspends the article to be coated 20, the powder coating material that becomes overspec will fall naturally due to the vibration. This overspec powder coating is a natural deposit of non-rubbing powder coating. Thereafter, the painted object 20 is conveyed to a baking drying furnace in a tact operation, and unloaded after baking.

  In this second embodiment, as a method of adjusting the film thickness, not only the discharge amount from the frictional charging gun 25 and its current value (charge adjustment of the powder coating) but also the powder coating that is not frictionally charged is used. A fixed amount was put into the paint tank.

  In FIG. 7, the powder coating tank 21 is replenished with the powder coating from the new powder tank 32 by the injector 33, and the spilled powder from the powder coating tank 21 is recycled to the frictional charging gun 25 for reuse. Yes.

Next, a third embodiment of the present invention will be described with reference to FIGS.
In the third embodiment, the object to be coated 20 is a coil spring of an automobile.

  Unlike the above-described first and second embodiments, the third embodiment is a continuous operation type coating apparatus.

  As shown in FIG. 8, the coil spring that is the article to be coated 20 that is hung on the conveyor 34 is continuously coated.

  The conveyor speed is 3.5 m / min, and two coil springs that are the objects to be coated 20 are suspended and conveyed in parallel. The powder coating tank 21 is 700 mm (W) × 1200 mm (L) × 600 mm (H), and a resin porous material 23 having a thickness of 200 mm is installed on the bottom as a flow pad.

  The conveyor 34 descends near the powder coating tank 21 and enters the powder coating tank 21.

  In this example, an epoxy resin having an average particle size of 37 μm was used as the powder coating material. In order to supply the powder coating material charged with friction charging into the powder coating material tank 21, a friction charging gun 25 was used. The gun body of the frictional charging gun 25 is not immersed in the powder paint in the powder paint tank 21, and a gun tip nozzle attached to the tip of the gun body is fixedly arranged in the fluidized bed 21a. The number of guns is 1 gun x 2 (opposite) = 2 guns, 2 stages, a total of 4 guns. The discharge rate is 35 g / min per gun.

  When the coil spring that is the article to be coated 20 enters the powder coating tank 21, the atomized powder coating that exists in the atomizing layer 21b above the fluidized bed 21a adheres rapidly. Then, it is discharged from the fluidized bed 21a again while being immersed in the fluidized bed 21a.

  In this embodiment, when immersed in the fluidized bed 21a, the powder coating material abruptly adheres. In particular, even in places where the number of windings at the upper and lower parts of the spring is high, there is no air blow-off as in general electrostatic gun coating, so there is no difference in attachment and uniform coating is instantaneously possible. Therefore, it is not necessary to dispose the gun below the fluidized bed 21a.

  Moreover, peeling of the powder coating once adhered was not seen in the fluidized bed 21a. And after coating, the coating film of 80 micrometers of a regular film thickness was obtained by giving a vibration.

Next, a fourth embodiment of the present invention will be described with reference to FIGS.
The fourth embodiment is a coating device for a motor core and a rotor.

  By the way, a coating method using an electrostatic gun is generally used for a thin film type coating having a film thickness of 100 μm or less.

  And for the thick film type coating having a film thickness of 200 μm or more, electrostatic fluidized immersion coating as shown in FIG. 28 is used. In the electrostatic fluidized dip coating, a corona electrode 8 is installed on the porous material 9 in the insulating powder coating tank 6 and is passed through the atomizing layer 12 where the atomized powder coating on the fluidized bed 11 rises. Thus, an electric field is formed by the discharge from the electrode 8 (corona pin) placed on the porous material 9 to perform coating.

  In the present invention, since the coating in the fluidized bed 21a is possible, a coating method in which the atomized powder paint in the atomized layer 21b and the powder paint in the fluidized bed 21a are alternately applied is adopted.

  As shown in FIG. 10, an epoxy-based powder paint is accommodated in a fluidized state in a powder paint tank 21 formed of a conductive resin such as a conductive nylon resin. The powder coating tank 21 is grounded.

  In this embodiment, a suction device 35 (injector) for sucking the powder paint in the powder paint tank 21 is installed, and a non-conductive resin tube 36 is disposed at the tip of the suction device 35 so as to be non-conductive. The conductive resin tube 36 is connected to the upper part of the powder coating tank 21.

  When the powder paint passes through the inside of the non-conductive resin tube 36, the powder paint is frictionally charged due to friction between the non-conductive resin tube 36 and the powder paint, and the powder paint charged with friction charge is charged. It is supplied into the powder coating tank 21.

  A concave portion 38 is formed in the upper part of the powder coating tank 21 so that the article 20 conveyed by the conveyor 37 enters and exits, and the over powder from the concave portion 38 is returned to the powder coating tank 21. It has become.

  The lower part of the rotor of the motor, which is the object to be coated 20, is immersed in a fluidized bed 21a in the lower part of the powder coating tank 21, and the upper part is coated with the atomized particles in the atomized layer 21b. That is, coating is performed by repeating the atomized layer 21b and the fluidized bed 21a. As shown in FIG. 11, the motor rotor is conveyed to the outlet while being rotated by a conveyor 37.

  In the fourth embodiment, since the coating is performed by repeating the atomized powder paint of the atomized layer 21b and the fluidized powder paint of the fluidized bed 21a, a thick film of 350 μm or more is coated in a short time. It can be performed.

In the fourth embodiment, the powder coating is triboelectrically charged by passing through the non-conductive resin tube 36. For example, as shown in FIG. 12, the non-conductive resin mini-cyclone 39 (1 m ³ / min), the powder coating material may be conveyed by the injector 35 and frictionally charged by contact with the inside of the cyclone 39.

  Further, as shown in FIG. 13, a double non-conductive resin pipe 40 is installed in the powder coating tank 21, the inner cylinder 40 a is rotated, and the flowing air 24 from the lower part of the powder coating tank 21 is used. There is also a method in which the conveyed powder paint enters the gap between the inner cylinder 40a and the outer cylinder 40b, and the powder paint is rubbed. In this case, it is preferable that the inner cylinder 40a and the outer cylinder 40b are rounded to increase the friction effect. As described above, various types of powder paint friction methods are conceivable, but it is only necessary that a powder paint having a charge due to frictional charging can be introduced into the powder paint tank 21.

Next, a fifth embodiment of the present invention will be described with reference to FIGS.
In the fifth embodiment, the article 20 is a blade of an agricultural tool.

  In the case of the article 20 to be coated such as a blade of an agricultural tool, the specified film thickness is 40 to 80 μm, so that a thick film is formed by immersing in the fluidized bed 21a in the powder coating tank 21 as in the above-described embodiment. The required film thickness can be formed simply by passing the atomized portion of the atomized layer 21b above the fluidized bed 21a.

  In the fifth embodiment, as shown in FIG. 16, two rows of five objects to be coated 20 are arranged on one hanger, and a total of ten objects to be coated 20 are allowed to pass through the atomized layer in the atomized state. As a result, the article 20 is painted.

  As shown in FIG. 15, the coating apparatus is provided with a hollow tank 41 into which the atomized powder paint in the atomized layer 21 b above the fluidized bed 21 a flows in the center of the powder paint tank 21. The object to be coated 20 is put inside, and the powder paint is adhered in the hollow tank 41.

  That is, as shown in FIG. 14, a coating method using only the atomized powder paint on the upper part of the fluidized bed 21a was employed. The object to be coated 20 is inserted into the upper part of the powder paint tank 21 while being lowered toward the powder paint tank 21 by the conveyor 34, and the atomized powder paint adheres to the upper part of the powder paint tank 21, Since the area height of the atomized powder paint is limited, the article 20 enters the hollow tank 41. Next, the object conveyor is again raised, and at that time, the coating is finished by the atomized layer 21b. Thereafter, the object to be coated 20 is transported to a baking and drying furnace, and the coating is completed. In this embodiment, a part of the powder coating material of the atomized layer 21 b is deposited in the cavity tank 41. The deposited powder coating material is conveyed to the lowermost part by an air slider or vibration at the lower part in the cavity tank 41. Therefore, the bottom formed by the porous material 23 is inclined toward the injector 33 and returned to the powder coating tank 21 by the injector 33 by the powder coating amount detection leveler. In this embodiment, the hollow tank 41 is installed in the fluidized bed 21a. However, a plurality of powder coating tanks 21 may be installed, and the hollow tank 41 may be installed between them.

Next, a sixth embodiment of the present invention will be described with reference to FIGS.
In the sixth embodiment, the object 20 is a sirocco fan blade shown in FIG.

  As shown in FIG. 17, the sirocco fan has a large number of blades arranged in a small gap so that the entire blade has a circular shape like a spiral. Therefore, in the sixth embodiment, as shown in FIGS. 18 and 19, a powder coating tank 21 having a circular tank shape is provided so that the powder coating that is frictionally charged enters the gap between the blades. In use, the tip of the frictional charging gun 25 is obliquely inserted from the periphery of the powder coating material tank 21 at a constant interval.

  The powder coating tank 21 has a fluidized layer 21a in which the powder coating is in a liquid state at the bottom by the fluidized air 24 from the bottom, and an atomized layer 21b in which the powder coating drifts in the atomized state at the top. Is formed. The total number of gun tip nozzles of the frictional charging gun 25 is 16, which is inserted at an angle of about 30 ° with respect to the wall surface of the powder coating tank 21, and the frictionally charged powder coating material supplied from the gun tip nozzle is powdered. It is mixed with the powder coating material in the body coating tank 21, and the lower fluidized bed 21a and the upper atomized layer 21b stay while rotating spirally.

  The sirocco fan that is the object to be coated 20 is suspended from the hanger 22 and is put into and out of the powder coating tank 21 by tact operation. A shutter 42 that opens and closes when a sirocco fan that is the object to be coated 20 is taken in and out is provided on the upper part of the powder coating tank 21.

  In the sixth embodiment, painting is performed by inserting the gun tip nozzle obliquely with respect to the wall surface of the powder coating tank 21, but this gun tip nozzle is inserted at a right angle with respect to the wall surface of the powder coating tank 21. When this is done, a skel is generated at the back of the base of the blade of the sirocco fan.

  Thus, in the case of the article 20 to be coated such as a sirocco fan, it is preferable to insert the gun tip nozzle obliquely with respect to the wall surface of the powder coating tank 21 as in the example of FIG. ) Install the bendable angle adjustment nozzle shown in (b), change the angle of the gun tip nozzle up and down, left and right while looking at the shape and surroundings of the object to be coated 20, and turbulence in the powder coating tank 21 You may make it raise.

  Moreover, in the said 6th Example, although the powder coating material tank 21 was made into the circular tank, it is also possible to make it a shape like the square (box) type | mold of Examples 1-6.

Next, a seventh embodiment of the present invention will be described with reference to FIGS.
The object to be coated 20 of the seventh embodiment is a motor component similar to that of the fourth embodiment, and the seventh embodiment is an example in which painting is performed with the same equipment as that of the fourth embodiment.

  The motor component of the article 20 in the seventh embodiment is a component that requires a thin film of 50 to 100 μm instead of a thick film exceeding 200 μm as in the fourth embodiment.

  For this reason, in the case of Example 4, the lower part of the motor component which is the article to be coated 20 was immersed in the fluidized bed 21a in the lower part of the powder coating tank 21, and the coating was performed. In the case of the seventh example, Is applied only with the atomized particles of the atomized layer 21b at the upper part of the powder coating tank 21, so that the article 20 is not immersed in the lower fluidized layer 21a.

  In the seventh embodiment, a suction device 35 (injector) for sucking the powder paint in the powder paint tank 21 is installed, and a non-conductive resin tube 36 is disposed at the tip of the suction device 35. By passing the powder paint through the inside of the non-conductive resin tube 36, the non-conductive resin tube 36 and the powder paint are rubbed to cause frictional charging of the powder paint.

  A discharge nozzle 43 is connected to the non-conductive resin tube 36 so that the frictionally charged powder paint is supplied from the tip of the discharge nozzle 43 to the substantially upper center of the fluidized bed 21 a of the powder paint tank 21. Yes.

  In the seventh embodiment, as described above, in order to form a thin film coating, it is necessary to perform coating only with the atomized particles of the atomized layer 21b on the upper part of the powder coating tank 21, but the discharge nozzle When the charged powder coating material is ejected from the tip of 43 to the position approximately at the center of the upper part of the fluidized bed 21a of the powder coating tank 21, the powder coating material of the fluidized bed 21a is atomized by the ejected powder coating material. There is a risk of winding onto the layer 21b.

  For this reason, a semi-circular hollow hoisting prevention shade 44 having an open lower surface is installed at substantially the center of the upper part of the fluidized bed 21 a of the powder coating tank 21, and the tip of the discharge nozzle 43 is placed in the hoisting prevention shade 44. The powder coating material discharged from the discharge nozzle 43 is indirectly supplied toward the porous material 23 on the lower surface so as not to be supplied directly to the atomized layer 21b.

  Thus, the powder coating material indirectly supplied toward the porous material 23 on the lower surface is mixed with the powder coating material in the powder coating material tank 21, so that the porous material 23 in the lower part of the powder coating material tank 21 is mixed. It stays in the upper part of the powder coating tank 21 while being gently atomized by the flowing air 24 from the air.

  As described above, when the semicircular hollow anti-roll-up shade 44 is used, the movement of the staying powder coating becomes slow, so that a uniform thin film coating can be applied to the concave portion of the article 20 to be coated. The film thickness inside the rotor which is the thing 20 can be 50-70 micrometers.

  The semi-circular hollow anti-roll-up shade 44 may be installed at the center of the powder coating tank 21 as described above, or as shown in FIG. You may make it mount | wear with the front-end | tip of the discharge nozzle 43. FIG. The roll-up prevention shade 44 attached to the tip of each discharge nozzle 43 is formed in a shape that surrounds the entire discharge nozzle 43 and has an outflow hole on the side.

  In the seventh embodiment, the powder coating material is supplied to the upper part of the powder coating material tank 21 from the new powder tank 49.

Next, an eighth embodiment of the present invention will be described with reference to FIGS.
In the eighth embodiment, the object to be coated 20 is a stator of a wind power generation motor shown in FIG. 23, and a film thickness of 200 μm or more is required.

  As shown in the end view of FIG. 22, the stator has a cylindrical shape and is provided with a large number of recesses on the inner diameter surface for forming windings extending in the axial direction. To try to form.

  The size of the stator is, for example, about 80 mm outer diameter × 53 mm inner diameter × 65 mm height, and the gap between the recesses is as narrow as about 7 mm.

  Moreover, since the desired film thickness of the insulating coating applied to the inner surface of the recess is a thick film of 200 μm or more, it cannot be applied with a normal powder coating gun.

  The coating apparatus shown in FIG. 24 is provided with an outlet 45 for the powder coating that matches the concave shape of the end face of the stator on the upper surface of the powder coating tank 21 in which the powder coating is accommodated in a fluidized state. Thus, the stator is installed by aligning the recesses on the end face of the stator with the outlet 45.

  A suction hood 46 is installed above the stator installed on the upper surface of the powder coating tank 21, and the powder coating in the powder coating tank 21 is sucked by the dust collector 47 and passes through the recess of the stator.

  In the powder coating tank 21, a porous material 23 is installed in the lower part of the tank, and the powder coating material contained in the powder coating tank 21 is fluidized by flowing air 24 supplied below the porous material 23. I have to. The lower part of the powder paint in the powder paint tank 21 is a fluidized bed 21a in a fluidized state, and the upper part is an atomized layer 21b in an atomized state.

  The powder coating layer 21 uses a circular tank, and twelve gun tip nozzles 25 are installed around it.

  As described above, the gap between the concave portions of the stator is as narrow as 7 mm, and uniform coating is required.

  For this reason, in the example of FIG. 24, a net 48 is installed in the atomized layer 21 b of the powder coating tank 21. The mesh of the mesh 48 used 7 mesh. In order to prevent the mesh 48 from being clogged, a vibration device 49 such as an air vibrator was installed at the center of the mesh 48. The discharge amount is 60 g / min, and the discharge is performed for 15 seconds. Thereafter, the article 20 is reversed and discharged again for 15 seconds.

After the coating, the excess powder paint (the place where coating is not necessary) was removed, and curing was performed at high frequency. The vibration device 49 may not be installed depending on the shape and fluidity of the powder paint particles.
The powder paint discharged from the gun tip nozzle is agitated and mixed with the powder paint in the fluidized bed 21a. Thereafter, it passes through the mesh 48 in the upper layer of the tank and rises uniformly into the powder coating layer 21.

  The powder coating material of the atomized layer 21b having electric charge passes through and adheres to the gap of the concave portion 7 mm of the stator while moving slowly by the resistance of the mesh 48. If this net 48 is not installed, the amount of adhesion of the gaps varies, and the passage speed of the powder coating material of the atomized layer 21b is increased, and a phenomenon of blowing off occurs in a part thereof, but the net 48 is installed. As a result, the blow-off phenomenon is eliminated, and the film thickness can be set to 230 to 270 μm.

  The mesh 48 may be installed on the upper part of the fluidized bed 21a as shown in FIG. 25 or on both the upper part of the fluidized bed 21a and the lower part of the atomized layer 21b as shown in FIG.

20 Substrate 21 Powder coating tank 21b Atomizing layer 21a Fluidized bed 22 Hanger 23 Porous material 24 Fluidized air 25 Friction charging gun 26 Circulating path 27 Vibrating sieve 28 Exit 29 Receiving tank 29a Injector 30 Reciprocator 31 Conveyor 32 New Powder tank 33 Injector 34 Conveyor 35 Suction device 36 Non-conductive resin tube 37 Conveyor 38 Recess 39 Cyclone 40 Non-conductive resin pipe 40a Inner cylinder 40b Outer cylinder 41 Cavity tank 42 Shutter 43 Discharge nozzle 44 Roll-up prevention shade 45 Exit 46 Suction hood 47 Dust collector 48 Net 49 New powder tank

Claims (13)

  A powder paint tank charged with triboelectric charge is contained, a powder paint fluidized bed is installed in the lower part, and a powder paint tank with a powder paint atomization layer in the upper part. Alternatively, a powder coating apparatus characterized by adhering a grounded coating material to at least one of the atomized layers so as to attach a frictionally charged powder coating to the coating material.   The powder coating apparatus according to claim 1, wherein a powder coating that is not charged is mixed in the powder coating tank.   3. The powder coating apparatus according to claim 1, wherein the means for applying an electric charge to the powder coating contained in the powder coating tank is a frictional charging gun.   The powder coating apparatus according to claim 1 or 2, wherein a friction charging device that frictionally charges the powder coating contained in the powder coating tank is installed in the powder coating tank.   5. The powder coating apparatus according to claim 4, wherein a friction charging device made of a non-conductive resin is provided in the fluidized bed in the powder coating tank so as to bring the frictional charge into contact with the powder coating.   The powder coating apparatus according to any one of claims 1 to 5, wherein a cavity through which an object to be coated with a frictionally charged powder coating passes is installed in the powder coating tank.   The powder coating apparatus according to any one of claims 1 to 6, wherein the powder coating tank is formed of a conductive material such as a non-conductive resin, metal, or conductive resin.   8. The powder coating apparatus according to claim 1, wherein a discharge nozzle for supplying the frictionally charged powder coating is obliquely installed on the wall surface of the powder coating tank.   The powder coating apparatus according to claim 8, wherein the tip of the discharge nozzle is formed by a bendable angle adjusting nozzle.   The powder coating apparatus according to any one of claims 1 to 9, wherein the powder coating tank is a circular tank.   The powder coating apparatus according to any one of claims 1 to 10, wherein the powder coating tank is indirectly supplied with the frictionally charged powder coating.   12. The net according to any one of claims 1 to 11, wherein a net for gradually increasing the rising speed of the atomized powder paint is installed in at least one of the fluidized bed or the atomized layer formed in the powder paint tank. The powder coating apparatus described in 1. The powder coating apparatus according to claim 12, wherein a vibration device is installed on the net.

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