JPH09155244A - Powder coating nozzle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder coating nozzle device suitable for applying a powder coating agent in the shape of a belt. SOLUTION: This device is constituted so that a nozzle body 2 can be provided with a slit-shaped nozzle opening 5 opened long and thin along the axial direction of the nozzle body 2 and that one or plural electrode pins 8 conductively connected to a high voltage generator 13 and having a resistance value for spark prevention can be attached exposed to the bottom part of the nozzle opening part 5. In this case, the nozzle opening part 5 is divided into upper and lower parts by an air permeable porous plate 20. To the divided chamber above the porous plate 20, a feeding line 6 for a powder coating agent and a recovery line for recovering a powder coating agent 17 that has not been stuck on a material to be coated are fitted. To the divided chamber below the porous plate 20, a fluidization accelerating and cleaning air feeding line 21 for improving the adhesiveness rate of the powder coating agent is fitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder coating nozzle device suitable for coating powder on an object to be coated in a strip shape in the field of powder coating and the like. TECHNICAL FIELD The present invention relates to a powder coating nozzle device suitable for coating a strip of powder on a longitudinal weld seam line on the inner surface of a can of a remarkable beverage can or the like.

[0002]

2. Description of the Related Art Conventionally, when canning beverages and food products, the container can is corroded by the contents,
On the contrary, the inner surface of the can has been coated for the purpose of preventing the components of the can material from being eluted into the contents and impairing the umami taste.

Due to recent advances in can-making technology and coating technology, cans of foods and the like are mostly manufactured from coated steel sheets, which are so-called pre-coated metals, which have been previously coated. However, except for squeezed cans such as aluminum materials, which are so-called two-piece cans and drawn cans, a welding process is required at the joints in the vertical direction of the cans. A coating process for coating in a strip shape is required.

Conventionally, a liquid coating agent has generally been used as a coating agent for coating the welding line in a strip shape. It is no exaggeration to say that almost all of the beverage cans of a small volume, which have been remarkably popularized recently, for example, those having a diameter of 52 to 65 mm and an internal volume of 190 to 350 ml class use a liquid coating agent. Generally speaking, powder coating technology is technically difficult in many respects as compared with liquid coating technology and stable coating is difficult to obtain, and the nozzle device for powder coating agent is liquid coating technology. It was also due to the fact that it was structurally larger than the nozzle device for chemicals.

However, recently, from the viewpoints of preventing air pollution, foul odors, environmental pollution due to organic solvents, etc., and the advantage of a solvent-free coating agent for umami, etc. With the increasing demand for development of coating technology using powder coating agents, coating processing of cans using powder coating agents is being attempted. As an example of a powder coating nozzle device having a structure suitable for such an application, there is known a powder coating nozzle device disclosed in Japanese Patent Laid-Open No. 7-189955, which was filed by the applicant of the present application and published. The present application relates to an improved technique for this.

A representative example of the powder coating nozzle device disclosed in Japanese Unexamined Patent Publication No. 7-189955 will be briefly described below with reference to the drawings. That is, FIG. 5 is a prior art of Japanese Patent Laid-Open No. 7-
FIG. 6 is a vertical sectional view showing an embodiment of the powder coating nozzle device disclosed in Japanese Patent No. 189955, and FIG. 6 is a horizontal sectional view of FIG.

First, in FIGS. 5 and 6, reference numeral 1 denotes a powder coating nozzle device, and the powder coating nozzle device 1 is
The seam welds on the inner surface of small beverage cans, etc.
It is constructed so as to be suitable for coating in a strip shape, and is arranged in series in the downstream of a seam welder (not shown) in a series of can making steps. Reference numeral 2 denotes a nozzle body, which is made of plastic such as polypropylene and has a welding line 4 on the inner surface of a can body 3 which is an object to be coated.
A nozzle opening 5 is provided which is opened in the shape of an elongated slit in the axial direction (moving direction of the object to be coated). The axial length of the nozzle opening 5 is preferably at least 20 mm or more.

The supply pipe 6 for the powder coating agent 17 sent from a seam welder (not shown) and the recovery pipeline 7 for recovering the powder coating agent 17 not adhered to the object to be coated are the nozzles. It is provided so as to communicate with the nozzle opening 5 of the main body 2. Reference numeral 8 is an electrode pin made of a spark-proof type carbon fiber, and the electrode pin 8 has an electric resistance value of 10 ⁵ to 10 ⁷ Ω · cm, preferably 10 ⁶ Ω.
-A thing of about cm is used. When the electric resistance value of the electrode pin 8 deviates from this value, spark discharge is generated or desired corona discharge cannot be obtained. A plurality of electrode pins 8 are axially provided in the nozzle opening 5 of the nozzle body 2 with an insulating material 9 made of a silicone material interposed therebetween. Reference numeral 10 is an electrode rod made of a carbon fiber material or the like, and the electrode rod 10 is provided with a nozzle body 2 through an insulating coating material 11 made of a silicone material.
Embedded therein, the electrode rod 10 and the electrode pin 8 are connected by a connection pin 12 made of a conductive material. The electrode pins 8 may have a configuration in which bristles are continuously planted in the longitudinal direction of the nozzle openings 5.

Reference numeral 13 denotes a high voltage generator, which is connected to the nozzle body 2 via a plastic support member 14 made of polypropylene, MC nylon or the like, and outputs from the high voltage generator 13. The terminal portion is connected to the electrode rod 10. Reference numeral 15 is a brush or blade provided on both sides of the nozzle opening 5, and the brush or blade 15 is made of flexible glass fiber, nylon,
It is made of plastic such as PET and has a function of preventing the width of the powder coating agent 17 ejected from the nozzle opening 5 toward the object to be coated from unnecessarily widening. 1
6 is a part of a power supply cable of the high voltage generator 13, 17 is a powder coating agent supplied together with air for transportation, and 18 is a can which is an object to be coated during coating operation. This shows that the body 3 is grounded.

The operation of the powder coating nozzle device according to the above-mentioned prior art will be described. A cylindrical can body 3 in which a seam welder welds the longitudinal seams of a small beverage can or the like to be coated is described. , Is continuously supplied from the upstream side on the left side of FIG.
Then, the powder coating agent 17 supplied together with the carrier air is supplied to the supply pipeline 6 via a pipeline such as a hose (not shown). High voltage generator 13 to electrode rod 1
0 and the high voltage supplied to the electrode pin 8 via the connection pin 12 generate corona discharge due to the potential difference between the electrode pin 8 and the object to be coated, that is, the grounded body 18, that is, the can body 3. As the powder coating agent 17 passes through, the powder coating agent 17 is electrostatically charged and adheres to the can body 3, which is the object to be coated, by electrostatic Coulomb force.

The powder coating agent 17 adhering to the can body 3 is subjected to heat treatment in a heating furnace (not shown) provided adjacent to the downstream side of the powder coating nozzle device 1 to form a coating film. It is formed. Further, the powder coating agent which has not adhered is recovered to the recovery tank or the like through the recovery conduit 7 and a conduit such as a hose (not shown).

[0012]

The above-mentioned conventional powder coating nozzle device has the following problems. That is, when the powder coating operation is continuously performed for a long time, the stall powder coating material 17 adheres to the bottom of the nozzle opening 5 or the tip of the electrode pin 8 or is ionized to a reverse potential for some reason. The deposited powder coating material 17 adheres, which causes a decrease in electrostatic force, a decrease in coating efficiency of the powder coating material 17, or a variation in coating thickness. The state in which the powder coating agent has adhered to the bottom of the nozzle opening is shown by E in FIG.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a powder coating nozzle structure suitable for coating a powder coating agent in a strip shape. Powder coating agent that adheres to the openings to reduce electrostatic force, coating efficiency does not vary, and coating thickness does not vary. It is an object to provide a nozzle device.

[0014]

Means for Solving the Problems The present invention has the following configuration to achieve the above object. That is, the nozzle body is provided with a slit-shaped nozzle opening which is elongated along the axial direction of the nozzle body, is electrically connected to the high voltage generator, and has a resistance value for preventing sparks. Or a powder coating nozzle device provided with a plurality of electrode pins exposed at the bottom of the nozzle opening, wherein the nozzle opening is vertically divided by an air permeable porous plate, and the upper compartment of the porous plate is divided. Is provided with a powder coating agent supply pipeline and a recovery pipeline for recovering the powder coating agent that did not adhere to the object to be coated, and the lower compartment of the porous plate has a powder coating agent. The powder coating nozzle device is characterized by being provided with an air supply pipe line for flow promotion and cleaning for improving the agent coating rate.

Further, the powder coating nozzle device is characterized in that a saw blade-shaped electrode plate is used instead of the one or more electrode pins.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described. In the present invention, since the powder coating nozzle device having the above-described structure is used, the powder coating agent supplied from the supply pipeline to the slit-shaped nozzle opening along with the carrier air is in the axial direction of the nozzle body, that is, Occurs between the object to be coated and one or more electrode pins or sawtooth-shaped electrode plates exposed at the bottom of the slit-shaped nozzle opening that is elongated in the moving direction of the object to be coated. The electrostatic charge is sufficiently electrostatically applied by the corona discharge to be applied to the object to be coated.

At this time, an appropriate amount is placed in the lower compartment of the nozzle opening which is divided into upper and lower parts by a breathable porous plate in which a large number of holes having a size that does not allow the powder coating agent used to pass through are formed. The powder coating agent is in a fluidized state by supplying air for accelerating the flow of the powder coating agent and cleaning air from the air supply pipe and blowing it through the porous plate toward the upper compartment of the porous plate. Is evenly promoted, and evenly contacts with corona discharge, the amount of electrostatic charge is increased, the coating efficiency is improved, and at the same time, it does not stay or adhere to the bottom of the nozzle opening. In addition, since the electrode pin for corona discharge or the sawtooth electrode plate is exposed at the bottom of the lower compartment divided by the porous plate, it does not come into direct contact with the powder coating agent. The pin or sawtooth electrode plate is not contaminated with the powder coating agent and is always kept clean.

Further, since the porous plate is made of a plastic material such as polyethylene or polypropylene, or a ceramic material, corona discharge is generated between the electrode pin and the object to be coated and passes through the porous plate. The coating agent is fully electrostatically charged. As a result, the electrostatic force is reduced, the coating efficiency of the powder coating material is reduced, and the variation in the coating thickness is eliminated.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The powder coating nozzle device of the present invention will be described in detail below with reference to the drawings showing its embodiments. It should be noted that, in the drawing, the portions having the same functions as those of the powder coating nozzle device of FIGS. 5 and 6 described as the prior art will be described with the same reference numerals as those of FIGS. 5 and 6. That is, FIG. 1 is a longitudinal sectional view showing an embodiment of the powder coating nozzle device of the present invention.
FIG. 2 is a transverse sectional view of FIG. 1.

In FIGS. 1 and 2, reference numeral 1 denotes a powder coating nozzle device, and the powder coating nozzle device 1 forms a strip-like seam welded portion on the inner surface of a small beverage can or the like to be coated. It is designed to be suitable for coating,
In a series of can making processes, the seam welder (not shown) is arranged downstream from the seam welder in series. Reference numeral 2 denotes a nozzle body, which is made of plastic such as polypropylene and is made up of two members 2a and 2b in terms of manufacturing. The nozzle body 2 is directed toward the welding line 4 on the inner surface of the can body 3 which is the object to be coated. The nozzle opening 5 is provided in the direction (moving direction of the object to be coated) in the shape of an elongated slit. The axial length of the nozzle opening 5 is preferably at least 20 mm or more.

The nozzle opening 5 is divided into an upper compartment 5a and a lower compartment 5b by a porous plate 20 innumerable holes having a size not to pass the powder coating agent 17 to be used. The porous plate 20 is made of a plastic material such as polyethylene or polypropylene, or a ceramic material.

A supply conduit 6 for the powder coating agent 17 sent from the seam welder side and a recovery conduit 7 for recovering the powder coating agent 17 not adhered to the object to be coated.
Are provided in communication with the upper compartment 5a of the nozzle opening 5 of the nozzle body 2. Also, in the lower compartment 5b,
An air supply conduit 21 for promoting flow and cleaning for improving the coating rate of the powder coating agent is provided. 8 is an electrode pin made of a carbon fiber of a spark prevention type, and the electrode pin 8 has an electric resistance value of 10 ⁵ to 10 ⁷ Ω.
-Cm, preferably about 10 ⁶ Ω-cm is used. When the electric resistance value of the electrode pin 8 deviates from this value, spark discharge is generated or desired corona discharge cannot be obtained.

A single electrode pin 8 or a plurality of electrode pins 8 are provided so as to be exposed in the lower compartment 5b of the nozzle opening 5 of the nozzle body 2 through an insulating material 9 made of a silicone material. ing. Reference numeral 10 denotes an electrode rod made of a carbon fiber material or the like. The electrode rod 10 is embedded in the nozzle body 2 via an insulating coating material 11 made of a silicone material.
0 and the electrode pin 8 are connected by a connection pin 12 made of a conductive material. The electrode pins 8 may have a configuration in which bristles are continuously planted in the longitudinal direction of the nozzle openings 5.

Reference numeral 13 is a high voltage generator, which is connected to the nozzle body 2 via a plastic support member 14 made of polypropylene, MC nylon, or the like, and outputs from the high voltage generator 13. The terminal portion is connected to the electrode rod 10. Reference numeral 15 is a brush or blade provided on both sides of the nozzle opening 5, and the brush or blade 15 is made of flexible glass fiber, nylon,
It is made of plastic such as PET and has a function of preventing the width of the powder coating agent 17 ejected from the nozzle opening 5 toward the object to be coated from unnecessarily widening. 1
6 is a part of a power supply cable of the high voltage generator 13, 17 is a powder coating agent supplied together with air for transportation, and 18 is a can which is an object to be coated during coating operation. This shows that the body 3 is grounded.

The operation of the powder coating nozzle device 1 according to the above-mentioned embodiment of the present invention will be described. A cylinder formed by welding a vertical seam of a small beverage can or the like to be coated with a seam welder (not shown). The can body 3 is continuously supplied from the upstream side on the left side in FIG. Further, the lower compartment 5 of the nozzle opening 5 divided by the porous plate 20 of the powder coating nozzle device 1
Compressed air 22 is supplied to b through an air supply conduit 21 from an air supply device (not shown), and is blown out to the upper compartment 5a through the porous plate 20.

The powder coating agent 17 supplied together with the carrier air via a powder supply device (not shown) and a conduit such as a hose is divided by the porous plate 20 through the supply conduit 6. Upper compartment 5a of the nozzle opening 5
Supplied to

Electric power supplied from a power source (not shown) to the high voltage generator 13 via the power supply cable 16 is converted into a high voltage by the high voltage generator 13 and then via the electrode rod 10 and the connection pin 12. Corona discharge is generated by passing through the porous plate 20 due to the potential difference between the electrode pin 8 and the object to be coated, that is, the can body 3 that is grounded to the ground 18, and the electric field is powder coated. As the agent 17 passes, the powder coating agent 17 is electrostatically charged and adheres to the can body 3, which is the object to be coated, by electrostatic Coulomb force.

In the nozzle opening 5, the powder coating agent 17 is promoted in a fluidized state by the compressed air 22 blown through the porous plate 20, and thereby uniformly contacts the corona discharge, so that the electrostatic charging efficiency is improved. The coating efficiency can be improved. Still, the powder coating agent which has not adhered is recovered by the powder recovery device (not shown) through the recovery pipeline 7 together with the conveying air and the compressed air 22. Therefore, the stagnant powder coating agent does not adhere to the inside of the nozzle opening 5 and is always kept clean, and the electrode pin 8 exposed in the lower compartment 5b is maintained.
Does not come into direct contact with the powder coating agent 17, so that the powder coating agent 17 does not adhere and become dirty, and the electrostatic force does not decrease. As a result, it is possible to always perform stable and high-quality coating.

Next, another embodiment will be described with reference to FIGS. In this embodiment, a saw blade-shaped electrode plate 30 is provided in place of the electrode pin 8 of the embodiment described with reference to FIGS. 1 and 2, and other configurations are similar to those of the embodiments described with reference to FIGS. Exactly the same. The saw blade-shaped electrode plate 30 is made of a conductor such as metal or carbon or a semiconductor, and is embedded in the lower compartment 5b of the nozzle opening 5 in the axial direction so that the tip of the saw blade is exposed. .

The high-voltage power supplied from the high-voltage generator 13 to the electrode plate 30 is the saw blade of the electrode plate 30 due to the potential difference between the electrode plate 30 and the grounded object to be coated, that is, the can body 3. A large number of corona discharges are generated from a large number of pointed tips, and the powder coating agent 17 is electrostatically charged by passing this electric field, and the powder coating agent 17 is electrostatically charged on the can body 3 as an object to be coated. Adhere to. At that time, the powder coating agent 17 is promoted in a fluidized state by the compressed air 22 blown through the porous plate 20 and uniformly contacts the corona discharge, so that the electrostatic charging efficiency is enhanced.

Still, the powder coating agent 17 which has stalled or not adhered in the nozzle opening 5 is collected with the compressed air 22 blown through the porous plate 20 through the recovery pipe 7 to recover the powder (not shown). Collected in the device. Therefore, the stagnant powder coating agent does not adhere to the inside of the nozzle opening 5 and is always kept in a clean state.
Further, since the electrode plate 30 exposed in the lower compartment 5b does not come into direct contact with the powder coating agent 17, the powder coating agent 17 does not adhere and become dirty, and the electrostatic force does not decrease. As a result, it is possible to always perform stable and high-quality coating.

Although the embodiments of the present invention have been described above, the present invention shows that the powder on the longitudinal welding seam line of the inner surface of a can, such as a beverage can, which was conventionally difficult to coat with a powder coating agent. It was developed for the purpose of coating in a band shape with the above coating agent, and the explanation of the examples was made for the sake of convenience such as beverage cans. However, the object to be coated is not limited to the beverage can. For example, in the field of powder coating such as furniture and electric appliances, band coating of the powder coating agent is often necessary.

The band-shaped coating is not limited to a single row, but a plurality of powder coating nozzle devices of the present invention are provided in parallel,
Multiple rows of strip coating can be applied at the same time, and different powder coating agents can be supplied to the multiple rows of powder coating nozzle devices to obtain striped coating films made of different materials. Etc., its uses are wide. Further, by arranging a plurality of slit-shaped nozzle opening grooves in which electrode pins or electrode plates are arranged adjacent to each other in a plurality of rows in one nozzle body, wide surface coating is possible.

[0034]

Since the powder coating nozzle device of the present invention is constructed as described above, it has a powder coating nozzle structure suitable for coating the powder coating agent in a strip shape, Provided is a powder coating nozzle device capable of always obtaining a stable coating thickness without the electrostatic force being reduced due to the powder coating agent adhering, the coating efficiency being lowered, or the coating thickness being varied. can do.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of a powder coating nozzle device of the present invention.

FIG. 2 is a cross-sectional view of FIG.

FIG. 3 is a vertical sectional view showing another embodiment of the powder coating nozzle device of the present invention.

FIG. 4 is a transverse sectional view of FIG. 3;

FIG. 5 is a vertical sectional view of a conventional powder coating nozzle device.

FIG. 6 is a transverse sectional view of FIG. 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Powder coating nozzle device, 2 ... Nozzle main body, 3 ... Coated object (can body), 5 ... Nozzle opening part, 6 ... Supply line, 8 ... Electrode pin, 13 ... High voltage generator, 17 ... Powder Body coating agent, 20 ... Porous plate, 21 ... Air supply conduit, 30 ... Electrode plate,

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area B05B 5/16 B05B 5/16

Claims (2)

[Claims] 1. A nozzle main body is provided with a slit-shaped nozzle opening that is elongated along the axial direction of the nozzle main body, and is electrically connected to a high voltage generator and has a resistance value for preventing sparks. A powder coating nozzle device having one or a plurality of electrode pins exposed at the bottom of the nozzle opening, wherein the nozzle opening is divided into upper and lower parts by a breathable porous plate. The upper compartment is provided with a powder coating agent supply conduit and a recovery conduit for recovering the powder coating agent not adhered to the object to be coated, and the lower compartment of the porous plate is A powder coating nozzle device, which is provided with an air supply conduit for accelerating the flow and cleaning for improving the coating rate of the powder coating agent. 2. The powder coating nozzle device according to claim 1, wherein the powder coating nozzle device is configured by a saw-toothed electrode plate instead of one or a plurality of electrode pins.