JP2002320904A - Powder coating method for inside of can-body having bottom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder coating method to keep the stable quality a can-body having the bottom such as a drum by making a uniform coating film thickness of a powder coating material to coat the inside surface of the can- body having the bottom such as the drum, furthermore, to reduce a running cost of the powder coating material by minimizing the use amount. SOLUTION: The drum 1, as the can-body having the bottom, is upside down to direct the bottom 1b upper side and the opening 1c under side, and a coating gun 20 is inserted into the drum 1 from the opening 1c, positioned at the lower side of the drum 1. With rotation of the drum 1, the powder is adhered to the inside surfaces 1a and 1b by discharging the powder from the coating gun 20 by moving the coating gun 20 in upper and/or lower directions. The powder which is not adhered to the inside surface is recovered by a powder recovery device 50 arranged at the lower position of the drum 1 and then the recovered powder is supplied again to the powder gun 20 for the use of coating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder coating method for an inner surface (inner wall) of a bottomed can such as a drum having a bottom or a cylindrical container having a bottom.

[0002]

2. Description of the Related Art Conventionally, coating of the inner and outer surfaces of a drum can with a solvent (liquid) paint has been the mainstream. However, in recent years, environmental issues have been taken up, and water-soluble paint has been introduced as a countermeasure. ing. However, depending on the contents of the drum, coating performance may be required,
In that case, for example, coating with a powder coating such as polyethylene resin is applied.

[0003] As a method of coating the inner surface (inner wall) of such a drum can with a powder coating, as shown in FIG. 3, the drum 1 is placed with its opening 1c upward and its bottom 1b downward, so-called, The powder coating gun 2 is placed on the floor conveyor 3 in the normal vertical position, and the powder coating gun 2 is inserted into the drum 1 from the opening 1c of the drum 1 with the discharge port (spray port) 2a facing downward. The powder is sprayed from the discharge port 2a while being lowered, and the inner surface (inner wall) 1a of the drum can is sprayed.
Powder coating method has been adopted.

[0004]

However, as described above, when powder coating is performed with the drum 1 in a vertical position, powder coating that does not adhere to the inner surface 1a of the drum 1 accumulates on the bottom 1b, and the powder 1a is deposited on the bottom 1b. However, there is a problem that the film thickness becomes excessive. In FIG. 3, CP is the inner wall 1 of the drum 1.
a is a powder coating applied to a, and 0S is a powder coating deposited on the bottom 1b.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and the quality of the powder coating on the inner surface of a bottomed can body such as a drum can is made uniform so that the quality can be stabilized. It is an object of the present invention to provide a powder coating method for the inner surface of a bottomed can, which can reduce running cost by maintaining and using a minimum required powder coating material.

[0006]

In order to achieve the above object, the present invention has the following arrangement. (1) A powder coating method for coating an inner surface of a bottomed can body such as a drum can by discharging powder from a coating gun, wherein the bottomed can body has an upper side and an opening has a lower side. A gun is inserted into the can body from the opening below the can body, and powder is discharged from the painting gun while rotating the can body and moving the coating gun upward and / or downward. Then, the inner surface of the can was coated by being adhered to the inner surface.

(2) In the powder coating method for the inner surface of a bottomed can of the above (1), the powder that has not adhered to the inner surface of the can is recovered by a powder recovery device disposed below the can. ,
The recovered powder was supplied again to the coating gun and used for coating.

[0008]

In the powder coating method of the above (1), a bottomed can body such as a drum can is so-called, for example, in a painting booth which is a painting work place, with its bottom being upward and its opening being downward, so-called,
In the inverted state, for example, in a state of being hung and placed in a fixed position, it is rotated (rotated) about its longitudinal center axis. In this state, the paint gun is inserted into the inside of the can through the opening below the can with the powder paint discharge port (spray port) at the end thereof facing upward, and the powder of the paint gun is removed. The body paint discharge port is located inside the can body near the bottom of the can body.

In this state, the discharge of the powder from the coating gun is started. When the coating is started and the coating of the bottom of the can body and the inner wall at the periphery thereof is completed, the coating gun is gradually lowered inside the can body in the opening direction, and the inner wall is gradually coated with the powder. During this coating operation, the bottom of the can is located above and the opening is located below, so that the powder that has not adhered to the bottom or the inner peripheral wall of the can is removed from the opening of the can. It does not fall down and accumulate on the bottom as in the prior art, and the coating on the bottom does not become excessive. In addition, the can body is painted while rotating. For this reason, the bottom of the can is coated over the entire surface, and the inner peripheral wall is coated over the entire periphery, that is, the inner surface (the bottom and the inner peripheral wall) of the can is coated with a uniform film thickness over the whole.
This stabilizes the quality as the inner surface coating can body. In the present specification, the powder coating may be simply referred to as powder.

In the powder coating method of the above (2), the powder that has not adhered to the bottom or the inner wall of the can falls below the opening of the can, and the powder collecting device located below the can. Thus, it is recovered, supplied again to the coating gun, and provided for coating.
As a result, the loss of the powder coating is eliminated, the required minimum amount of powder is used, and the running cost is reduced.

[0011]

Next, an embodiment of the present invention will be described with reference to the drawings. 1 and 2 show one embodiment of a powder coating apparatus for a drum can as a bottomed can body applied to the method of the present invention. FIG. 1 is a front sectional view of the powder coating apparatus, and FIG. FIG. 2 is a schematic plan view of FIG. 1 and is a view mainly showing a coating procedure when a large number of drums are sequentially coated. In these figures, the same or corresponding parts as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 1, a drum can 1 as a bottomed can is suspended by a hanger 35 with a bottom 1b upward and an opening 1c downward at the upper center of the painting booth 30. . The hanger 35 is supported at its upper end by an overhead conveyor 32 which is located above the ceiling surface of the coating booth 30 and moves in the longitudinal direction of the coating booth 30, and is rotatably supported by the overhead conveyor 32. The upper part thereof passes through an opening at the center of the upper end of the coating booth 30.

A sprocket 44 is mounted on the upper portion of the hanger 35 near the fishing fulcrum to the conveyor 32.
The lower part of the hanger 35 is constituted by a plurality of legs formed of, for example, four round bars, and the lower end of each leg is bent outward to the inward bent portion at the end of the bottom of the drum can. The drum can 1 is turned upside down by the hanger 35 by being formed so as to be lockable, and the outer bent portion at the lower end of the leg of the hanger 35 is locked to the inner bent portion at the bottom of the drum 1. It can be suspended. Reference numeral 31 denotes an intake opening and an extraction opening of the drum 1 as a work to be coated provided on both side surfaces of the coating booth 30.

As shown in FIG. 2, a frame 45 provided outside the painting booth 31 is connected to and driven by a first winding conduction chain device 42 between the frame 45 and the upper surface of the ceiling. A second wrapped conduction chain device 43 is provided, and one end of the second wrapped conduction chain device 42 is connected to the electric motor 41 with a speed reducer, and is configured to be rotationally driven. The first and second winding conduction chain devices 42 and 43 and the electric motor 41 with a speed reducer constitute a work rotating device 40. 4
5 is a motor 41 of the workpiece rotation device 40, and
It is a frame that supports the second winding conduction chain devices 42 and 43.

As shown in FIG. 2, the hanger 35 is attached to the overhead conveyor 32 so as to be rotatable (rotated) at regular intervals in the direction of movement (rotation) of the overhead conveyor 32. The drum 1 to be coated is hung upside down with the bottom 1b up and the opening 1c down at a position before the opening 31 on the upstream side in the moving direction of the conveyor 32. The drum 1 is moved by rotating the conveyor 32 in the direction of the arrow shown in FIG.
When the coating booth 30 is moved to the position PA indicated by the solid line in the center in plan view, the coating booth 30 is stopped.
0 is applied.

While the drum 1 is being coated at the position PA, the drum 1 to be coated next is placed in the opening 3 on the upstream side.
The drum 1, which has been waiting at the first position WA and has already completed the painting operation, is located at the position P at the opening 31 on the other downstream side of the booth.
It is paused at F. The drum 1, which has been temporarily stopped and painted at the downstream opening position PF, is then transferred to the conveyor 3.
2 is removed at a position rotated a predetermined distance.

The drum can 1 is provided at the center of the coating booth 30 in a plan view, within a range where the second winding conduction chain device 43 of the work rotating device 40 extends. The teeth of a sprocket 44 attached to a hanger 35 suspending the drum 1 from the chain engage (engage), and the hanger 35 is rotated, whereby the chain rotates in the directions indicated by arrows in FIGS. 1 and 2. Is done.

As shown in FIG. 1, inside the coating booth 30, a vertical center axis of the drum 1 at a lower position A of the drum 1 suspended on the hanger at a center position PA of the coating booth 30 in plan view. The powder coating gun 20 is located at a substantially central position substantially coincident with the above, and a gun elevating device 25 located on the outer side of the coating booth 30 via a gun mounting bracket 21.
Is fixedly attached to the distal end of the gun mounting arm 26.

In the present embodiment, the coating gun 20 comprises three electrostatic coating guns 20a, 20b and 20c.
Each of them is positioned with the discharge port at the tip facing upward. Since the coating gun 20 is composed of three coating guns as described above, the coating time is shortened and the work efficiency is improved. The coating gun 20 is provided by a gun elevating device 25 so as to be vertically movable between a coating operation standby position indicated by reference numeral A in FIG.

At the lower end of the coating booth 30, a powder collecting device 50 is connected and mounted.
0, a plurality of (four in the present embodiment) cylindrical cartridge filters 51 as powder recovery modules are provided.
Are placed side by side so as to cross the powder recovery device. The cartridge filter 51 has a filtration surface on the outer peripheral portion of the cylinder, the interior is a space, and air that has passed through the interior of the coating booth 30 passes through the filtration surface on the outer peripheral portion of the cartridge filter 51 and enters the inside of the filter 51. When the powder is entrained, the powder entrained by the air is filtered on the surface of the filtering surface, so that the powder is collected.

The air from which the powder has been separated passes through the internal space of the cartridge filter 51 by a suction fan (not shown), and is discharged outside the powder recovery device 50 through the axial end of the filter 51. A powder storage hopper 52 having a gas-permeable porous plate 53 at the bottom is formed below the cartridge filter 51 of the powder recovery device 50, and a fluidized air supply chamber 54 is formed below the powder storage hopper 52. ing. The powder collected on the filtration surface on the outer peripheral portion of the cartridge filter 51 is dropped and stored in the powder storage hopper 52, and the powder stored in the hopper 52 is stored in the air supply chamber 5.
4 is fluidized by fluidized air dispersedly supplied into the storage hopper 52 through the perforated plate 53.

The fluidized powder is sucked by a powder pump (ejector pump) (not shown), conveyed through a powder return hose 13 to a cyclone 6 described later, collected and returned to the powder supply tank 5. . The fluidized air supplied into the storage hopper 52 flows into the filter 51, passes through the booth 30, and flows into the filter 51 together with a suction fan (not shown). It is discharged out of 50.

An air-flowing powder supply tank 5 having a vibrating screen 7 attached to the upper side of the gun elevating device 25 by returning to the upper part via a tube 8 is provided. An ejector pump 1 for powder delivery is provided at the top of the powder supply tank 5.
The pump 10 and the coating gun 20 are provided.
A powder supply hose 12a is connected to the coating gun 20a. Reference numeral 11 denotes a pipeline for supplying compressed air for powder supply to the pump 10. Although the pump 10 is not shown, two separate pumps 10 are provided.
The pumps 10 and the coating guns 20b and 20c constituting the coating gun 20 are connected by powder supply hoses 12b and 12c, respectively.

A cyclone 6 is provided at the upper end of the vibrating screen 7.
The powder supply hose 9 and the powder return hose 13 are connected to the side of the cyclone 6 respectively. An exhaust hose 14 is connected between the exhaust gas discharge pipe at the top of the cyclone 6 and the powder recovery device 50. The returned powder sent from the powder recovery device 50 to the cyclone 6 through the powder return hose 13 and collected is thrown into the vibrating screen 7 to remove impurities (dust contained in the air). Tank 5
And returned to painting.

A method of coating powder on the inner surface of the drum using the drum powder coating apparatus configured as described above will be described. At the painting position PA in the painting booth 30, the traveling of the overhead conveyor 32 is stopped, and the drum 1
Is suspended on the overhead conveyor 32 by the hanger 35 with the bottom 1b facing upward and the opening 1c facing downward, and is rotated by the work rotating device 40. In this state, the coating gun 20 is raised toward the drum 1 from the lower position A in the booth of FIG. 1 by the gun elevating device 25 and inserted into the inside of the drum 1 through the opening 1 c below the drum 1. 20, each of the coating guns 20a, 2a
The powder paint discharge ports 0b and 20c are positioned near the bottom 1b inside the drum 1 and the upward movement is stopped.

In this state, the powder supply pump (ejector pump) 10 attached to the powder supply tank 5 is operated, and each of the coating guns 20a, 20b,
20c to the powder supply hose 12a from the powder supply tank 5;
The supply of the powder paint is started via 12b and 12c, and the discharge of the powder paint is started from the discharge port of each coating gun. Thereby, the powder coating of the bottom 1b of the drum 1 and the inner wall 1a of the periphery thereof is performed. When the coating of the portion is completed, the gun elevating device 25 is operated, and the coating gun 20 is moved to the drum 1 at a desired speed to enable effective coating of the powder.
Of the drum 1 is gradually lowered in the direction of the opening 1c.
Is gradually coated with powder. In the coating method of the present embodiment, the inner surface of the drum 1 is coated in about 30 seconds per drum.

Although not shown, a high-voltage cable is connected between each of the coating guns 20a, 20b, and 20c of the coating gun 20 and a control device. The powder coating is electrostatically charged by corona discharge due to the high voltage supplied to each of the coating guns, and is discharged toward the inner surface of the drum 1 from the discharge port of each coating gun. As a result, the powder coating is applied to the inner surface of the drum 1.

During such a coating operation on the inner surface of the drum 1, excess powder paint that has not adhered to the inner surface (the bottom 1 b and the inner peripheral wall 1 a) passes through the opening 1 c of the drum 1 into the coating booth 30. It falls and is carried by the airflow flowing downward in the coating booth 30 to flow into the powder recovery device 50 below the coating booth 30. Collection device 5
The powder that has flowed into the cylindrical cartridge filter 51 is caught by the outer peripheral filtration surface of the cylindrical cartridge filter 51, dropped into the lower hopper 52, and passed through the powder return hose 13, cyclone 6, vibrating screen 7 and return pipe 8. It is returned to the body supply tank 5.

During the powder coating operation of the drum 1, the bottom 1 b of the drum 1 is located at the upper side and the opening 1 c is located at the lower side. The powder that has not adhered to the drum 1 falls below the outside of the drum 1 through the opening 1c below the drum 1 and does not accumulate on the bottom 1b. No thickening. Also, since the drum 1 is coated while being rotated, its bottom surface 1b
Is coated over the entire surface, and the inner peripheral surface 1a is also coated with a uniform film thickness over the entire circumference. That is, the inner surface of the drum 1 is coated with a uniform film thickness over the entire surface. This stabilizes the quality of the drum with the inner surface coated.

As described above, the bottom 1 of the drum 1
b and the powder that has not adhered to the inner wall 1a fall into the coating booth 30 outside the drum from the opening 1c of the drum 1 and are collected by the powder recovery device 50 located below the coating booth 30 below the drum 1. , Collected and again painted gun 20
And applied to the inner surface of the drum 1. As a result, the loss of the powder coating is eliminated, the required minimum amount of powder is used, and the running cost of the powder coating is reduced.

In the powder coating method of the present embodiment, while the inner surface of the drum 1 is being coated at the coating work position PA in the center of the coating booth 30, the drum 1 to be coated next is on standby. At the opening 31 on the inlet side of the drum 1 of the coating booth 30 at the position WA, the coating booth 3 at the temporary stop position PF of the drum 1 already coated.
In the opening 31 on the outlet side of the drum can 1, the drum can 1 is supported by the support.
The amount of air flowing into the painting booth 30 through 31 is reduced, and the power consumption of the suction fan is saved.
From this point, the powder coating running cost can be reduced.

In the powder coating method of the above embodiment, at the start of coating, the coating gun 20 is raised from the position A and the powder discharge port is placed at the position B close to the bottom 1b of the drum 1 so that the inner surface of the drum 1 The coating was started from the bottom 1b side of the drum 1 and the coating gun 20 was gradually lowered toward the opening 1a side. Conversely, when the coating was started, the coating gun 20 was raised from the position A to remove the powder. The body discharge port is placed at a position close to the opening 1c of the drum 1 and the inner surface of the drum 1 is painted from the opening 1c of the drum 1 toward the bottom 1b by gradually moving the coating gun 20 upward. Is also good. Further, a method may be used in which the operation of performing the inner surface coating while raising the coating gun 20 and the operation of performing the lowering while coating the coating gun 20 are combined.

In the above embodiment, the case where the bottomed can is a drum can is shown. However, the present invention is not limited to the case where the cross-sectional shape is circular, rectangular, square, or polygonal, and has a cylindrical shape having a bottom. The present invention can also be applied to cans having other shapes.

[0034]

As is clear from the above description, the present invention has the following excellent effects.

According to the structure of the first aspect, the inner surface (the bottom and the inner peripheral wall) of the bottomed can can be coated with a uniform film thickness. This makes it possible to obtain a stable inner coating can body.

According to the configuration of the second aspect, there is no loss of the powder coating, and the running cost of the powder coating can be reduced by using the minimum necessary amount of powder.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an embodiment of a powder coating apparatus for a drum can as a bottomed can body applied to the method of the present invention.

FIG. 2 is a schematic plan view of FIG. 1 and is a view mainly showing a coating procedure when a large number of drums are sequentially coated.

FIG. 3 is a schematic longitudinal sectional view illustrating a conventional method for coating powder on the inner surface of a drum can.

[Explanation of symbols]

 Reference Signs List 1 drum can (bottomed can body) 1a bottom (drum can) 1b inner wall surface (drum can) 1c opening (drum can) 2, 20 powder coating gun 20a, 20b, 20c electrostatic coating gun 5 powder supply tank 12a, 12b, 12c Powder supply hose 13 Powder return hose 25 Gun lifting / lowering device 30 Painting booth 31 Painting booth opening 32 Overhead conveyor 35 Hanger 40 Work (drum can) rotating device 41 Electric motor with reduction gear 42 First winding conduction chain device 43 Second Wrapping conduction chain device 44 Sprocket 50 Powder collection device 51 Powder collection cartridge filter PA Painting work position WA Painting standby position PF Painting end can pause position

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B05D 7/24 301 B05D 7/24 301A (72) Inventor Norihiko Hayashi 1-5 Katsushima, Shinagawa-ku, Tokyo No. 21 Toshin Building 8th Floor Nordson Corporation (72) Inventor Isao Yabuuchi 1-5-21 Katsushima, Shinagawa-ku, Tokyo Toshin Building 8th Floor Nordson Corporation F Term (Reference) 4D075 AA01 AA35 AA62 AA67 AA72 BB14Y DA13 DA19 DB01 DC42 EA02 EB13

Claims (2)

[Claims] 1. A powder coating method for coating an inner surface of a bottomed can body by discharging powder from a coating gun, wherein the bottomed can body has an upper side and an opening has a lower side. Into the can body through the opening below the can body, while rotating the can body, and discharging the powder from the coating gun while moving the coating gun upward and / or downward. Coating the inner surface of the can body by adhering to the inner surface of the can body. 2. The powder that has not adhered to the inner surface of the can is recovered by a powder recovery device disposed below the can, and the recovered powder is supplied again to the coating gun and used for coating. The powder coating method for the inner surface of a bottomed can according to claim 1, wherein