JP4721029B2 - Powder coating method for inner surface of bottomed can body - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides an inner surface (inner wall) of a bottomed can body having an opening having one end closed at the bottom and the other end opened, such as a drum can having a bottom or a cylindrical container having a bottom. The present invention relates to a powder coating method.
[0002]
[Prior art]
Conventionally, the inner and outer surfaces of drum cans have been mainly coated with a solvent (liquid) paint. However, in recent years, environmental problems have been taken up, and water-soluble paint has been introduced as a countermeasure. However, depending on the contents of the drum, coating film performance may be required, and in that case, coating with a powder paint such as polyethylene resin is performed.
[0003]
As shown in FIG. 3, the drum can 1 is coated with the powder can on the inner surface (inner wall) of the drum can 1 with its opening 1c facing upward and the bottom 1b facing downward, so-called normal vertical It is placed on the floor conveyor 3 as an installation state, and the powder coating gun 2 is inserted into the drum can 1 through the opening 1c of the drum can 1 with its discharge port (spraying port) 2a facing downward. In this manner, powder is sprayed from the discharge port 2a and the inner surface (inner wall) 1a of the drum can be powder-coated.
[0004]
[Problems to be solved by the invention]
However, as described above, when powder coating is performed with the drum can 1 placed vertically, the powder coating that does not adhere to the inner surface 1a of the drum can 1 accumulates on the bottom 1b, and the film thickness of the bottom 1b becomes excessive. was there. In FIG. 3, CP is a powder coating applied to the inner wall 1a of the drum 1 and 0S is a powder coating deposited on the bottom 1b.
[0005]
The present invention has been made in view of the above problems, and by maintaining the coating film thickness of the powder coating on the inner surface of a bottomed can body such as a drum can, the quality can be maintained stably. An object of the present invention is to provide a powder coating method for the inner surface of a bottomed can body that can reduce the running cost by using the minimum necessary powder coating material.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured as follows.
(1) A powder coating method in which the inner surface of a bottomed can body is coated by discharging powder from a coating gun, the bottomed can body having an opening with one end closed at the bottom and the other end opened. and which, with its bottom upwards to the conveyor running top the bottomed can body in a painting booth suspended with its opening downward, while rotating the the can body, and the powder the spray gun With the body discharge port facing upward, it is inserted into the inside of the can body from the lower opening of the can body, and the powder discharge port is positioned near the bottom of the can body from the powder discharge port. Powder discharge is started and the bottom of the can body and the inner wall of the periphery are painted, and then the powder is discharged from the powder discharge port while the coating gun is gradually lowered in the opening direction of the can body. together they are allowed to be painted by adhering to the inner wall of the can body, through the opening of the can body powder not adhered to the can inner surface It is dropped downward, by placing the air flow towards the inside of the painting booth downwardly by further suction fan, and the structure of coating the inner surface of the can body.
[0007]
(2) In the powder coating method for the inner surface of the bottomed can body according to (1), the powder that has not adhered to the inner surface of the can body placed on the air flow flowing downward in the coating booth , The powder was collected by flowing it into a powder collecting device arranged in the painting booth , and the collected powder was supplied again to the painting gun to be used for painting.
(3) In the powder coating method for the inner surface of the bottomed can body according to (2) above, the conveyor of the conveyor where the bottomed can body is suspended by running the coating booth on both sides of the coating booth. A painting booth with an inlet opening and an outlet opening for bottomed cans on the upstream and downstream sides of the moving direction respectively, and when the bottomed can body is painted in the painting booth, The bottomed can body to be applied waits at the intake opening position, and the bottomed can body that has already finished painting is stopped at the extraction opening position.
[0008]
[Action]
In the powder coating method of the above (1), a bottomed can body such as a drum can is so-called reversed in the interior of a painting booth, for example, a painting booth, with the bottom up and the opening down. For example, in a state where it is suspended and placed at a fixed position, it is rotated (rotated) around its longitudinal center axis. In this state, the coating gun is inserted into the can body from the lower opening of the can body with the powder coating discharge port (spraying port) at the end directed upward, and the powder of the coating gun is The body paint discharge port is positioned in the vicinity of the bottom of the can body inside the can body.
[0009]
In this state, the discharge of powder from the coating gun is started. When painting is started and the painting of the bottom of the can body and the inner wall at the periphery thereof is completed, the coating gun is gradually lowered in the opening direction inside the can body, and the inner wall is gradually powder coated. During the painting operation, the can body has an opening with one end closed at the bottom and the other end opened, and the bottom is located above and the opening is located below. The powder that has not adhered to the bottom or inner peripheral wall of the can falls down from the opening of the can body and is put on the air flow that is flowing downward in the painting booth by the suction fan. As a result, the powder that has not adhered does not accumulate on the bottom as in the prior art, and the coating film on the bottom does not become excessive. The can body is painted while rotating. For this reason, the bottom of the can body covers the entire surface, the inner peripheral wall extends over the entire periphery, that is, the inner surface (bottom and inner peripheral wall) of the can body is coated with a uniform film thickness over the entire surface. Thereby, the quality as an inner surface painting can body is stabilized. In the present specification, the powder coating material may be simply referred to as powder.
[0010]
In the powder coating method of (2) above, the powder placed on the bottom of the inner surface and the inner wall of the can body placed on the air flow flowing downward in the coating booth is disposed in the coating booth. It flows into the collecting device and is collected, and is supplied again to the painting gun for painting. As a result, the loss of the powder coating material is eliminated, and the required amount of powder used is reduced, thereby reducing the running cost.
In the powder coating method of (3) above, while a bottomed can body is being coated on the inside surface in the painting booth, the bottomed can body to be coated next is the intake side of the painting booth. Since the bottomed can already painted is stopped at the opening position on the take-out side of the painting booth, the air flowing into the painting booth through both openings The amount is reduced and the power consumption of the suction fan is saved. From this point, the powder coating running cost can be further reduced.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
1 and 2 show 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. 1 is a front sectional view of the powder coating apparatus, and FIG. It is a schematic plan view of FIG. 1, and is a figure which shows the coating point in the case of coating many drum cans sequentially. In these drawings, the same or corresponding parts as those in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted.
[0012]
In FIG. 1, a drum can 1 as a bottomed can body is hung by a hanger 35 with the bottom 1 b facing upward and the opening 1 c facing downward at the upper center of the painting booth 30. The hanger 35 is supported at the upper end by an overhead conveyor 32 that is located above the ceiling surface of the painting booth 30 and moves in the longitudinal direction of the painting booth 30, and the fishing hanger 35 is rotatably supported with respect to the overhead conveyor 32. The upper part of the coating booth 30 passes through the opening at the center of the upper end.
[0013]
A sprocket 44 is attached near the fishing fulcrum to the conveyor 32 in the upper part of the hanger 35. The lower part of the hanger 35 is composed of a plurality of legs made of, for example, four round steel bars, and the lower ends of the legs are bent outwardly to the inwardly bent part at the end of the drum can bottom. The drum can 1 is reversed by the hanger 35 by being formed so that it can be locked, and the outward bent portion at the lower end of the leg portion of the hanger 35 is locked to the inward bent portion at the bottom of the drum can 1. It can be suspended. Reference numeral 31 denotes an intake opening and an extraction opening of the drum can 1 as workpieces (workpieces) provided on both side surfaces of the coating booth 30.
[0014]
As shown in FIG. 2, the frame 45 provided outside the painting booth 31 has a first wrapping conduction chain device 42 between the frame 45 and the upper surface of the ceiling, and a second driven and driven by the device 42. A wrapping conduction chain device 43 is provided, and the second wrapping conduction chain device 42 is connected to one end of a motor 41 with a speed reducer and is 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 rotation device 40. Reference numeral 45 denotes a frame that supports the electric motor 41 of the work rotation device 40 and the first and second winding conduction chain devices 42 and 43.
[0015]
As shown in FIG. 2, the hanger 35 is attached to the overhead conveyor 32 so as to be able to rotate (spin) at regular intervals in its moving (turning) direction. The drum 1 to which coating is performed at a position before the opening 31 on the upstream side in the moving direction 32 is suspended in a reverse manner with the bottom 1b facing up and the opening 1c facing down. The drum 1 is moved by rotating the conveyor 32 in the direction of the arrow shown in FIG. 2, and stopped when moved to a position PA indicated by a solid line in the center of the coating booth 30 in plan view. Powder coating with the coating gun 20 is performed at PA.
[0016]
While the drum can 1 is being painted at the position PA, the drum can 1 to be coated next waits at the upstream opening 31 position WA, and the drum can 1 that has already been painted is the other end of the booth. Is temporarily stopped at an opening 31 position PF on the downstream side. The drum can 1 that has been temporarily stopped and painted at the downstream opening position PF is then removed at a position where the conveyor 32 has rotated a predetermined distance.
[0017]
The drum 1 is attached to the chain of the second wrapping conduction chain device 43 in the central portion of the painting booth 30 in a range where the second wrapping conduction chain device 43 of the work rotation device 40 extends. The teeth of the sprocket 44 attached to the hanger 35 that suspends the drum 1 are engaged (engaged), and the hanger 35 is rotated to rotate in the direction indicated by the arrow in FIGS.
[0018]
As shown in FIG. 1, the interior of the painting booth 30 substantially coincides with the longitudinal center axis of the drum can 1 at a lower position A of the drum can 1 suspended from the hanger at the center position PA in plan view of the painting booth 30. The powder coating gun 20 is fixed and attached to the distal end portion of the gun mounting arm 26 of the gun lifting device 25 located on the outer side of the coating booth 30 via the gun mounting bracket 21 at the substantially central position. Yes.
[0019]
In the present embodiment, the coating gun 20 is composed of three electrostatic coating guns 20a, 20b, and 20c, each of which is positioned with the discharge outlet at the tip facing upward. Since the painting gun 20 is composed of three painting guns as described above, the painting time is shortened and the work efficiency is improved. The coating gun 20 is provided by a gun lifting / lowering device 25 so as to be movable up and down between a painting work standby position indicated by symbol A in FIG.
[0020]
A powder recovery device 50 is connected to and attached to the lower end of the coating booth 30, and a plurality of (four in this embodiment) powder recovery modules are provided inside the powder recovery device 50. A cylindrical cartridge filter 51 is placed side by side so as to cross the powder recovery apparatus. The cartridge filter 51 has a filtration surface on the outer periphery of the cylinder, the inside is a space, and the air that has passed through the coating booth 30 passes through the filtration surface of the outer periphery of the cartridge filter 51 and enters the inside of the filter 51. When sucked, the powder entrained in the air is filtered on the surface of the filtration surface to collect the powder.
[0021]
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 to the outside of the powder recovery device 50 through the axial end of the filter 51. A powder storage hopper 52 having a breathable perforated plate 53 at the bottom is formed below the cartridge filter 51 of the powder recovery apparatus 50, and a fluidized air supply chamber 54 is formed below the powder storage hopper 52. ing. The powder collected on the filtration surface of 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 through the porous plate 53 from the air supply chamber 54. The fluidized air is fluidized by the fluidized air supplied and distributed in the hopper 52.
[0022]
The fluidized powder is sucked by a powder pump (ejector pump) (not shown), conveyed to a cyclone 6 described later through a powder return hose 13, 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, and a powder recovery device by a suction fan (not shown). 50 is discharged to the outside.
[0023]
Near the gun lifting and lowering device 25, an air flow type powder supply tank 5 which is returned to the upper part and attached with a vibrating screen 7 via a gutter 8 is installed. An ejector pump 10 for delivering powder is provided at the top of the powder supply tank 5, and a powder supply hose 12 a is provided between the pump 10 and the coating gun 20 a of the coating gun 20. Is connected. Reference numeral 11 denotes a conduit for supplying compressed air for powder supply to the pump 10. Although not shown, two pumps 10 are provided separately, and the powder supply hose 12b, between each of the pumps 10 and the coating guns 20b and 20c of the coating gun 20 are respectively provided. 12c is connected.
[0024]
A cyclone 6 is erected on the upper end of the vibrating screen 7, and a powder supply hose 9 and the powder return hose 13 are connected to the cyclone 6 on the sides thereof. An exhaust hose 14 is connected to the exhaust gas discharge pipe at the top of the cyclone 6 between the powder recovery device 50. The return powder sent from the powder recovery device 50 to the cyclone 6 through the powder return hose 13 and collected is put into the vibrating screen 7 to remove impurities (dust contained in the air) and passed through the return rod 8. It is returned to the tank 5 and again used for painting.
[0025]
A powder coating method for the inner surface of the drum can using the drum can powder coating apparatus configured as described above will be described. At the painting position PA in the painting booth 30, the overhead conveyor 32 stops traveling, and the drum can 1 is suspended on the overhead conveyor 32 in reverse by the hanger 35 with the bottom 1b up and the opening 1c down. It is rotated by the device 40. In this state, the coating gun 20 is raised from the lower position A in the booth of FIG. 1 by the gun lifting device 25 toward the drum can 1 and inserted into the drum can 1 from the opening 1c below the drum can 1, and the coating gun 20 The powder paint discharge ports of the respective 20 painting guns 20a, 20b, 20c are positioned in the vicinity of the bottom 1b inside the drum can 1 and the upward movement is stopped.
[0026]
In this state, the powder supply pump (ejector pump) 10 attached to the powder supply tank 5 is operated, and the powder supply hose is supplied from the powder supply tank 5 to each coating gun 20a, 20b, 20c of the coating gun 20. Supply of the powder paint is started via 12a, 12b, 12c, and discharge of the powder paint is started from the discharge port of each of the coating guns. Thereby, powder coating of the bottom 1b of the drum 1 and the inner wall 1a at the periphery thereof is performed. When the coating of the portion is completed, the gun lifting / lowering device 25 is operated, and the coating gun 20 is gradually lowered in the direction of the opening 1c inside the drum can 1 at a desired speed that enables effective powder coating. The inner peripheral wall 1a is gradually powder-coated. In the coating method of the present embodiment, the inner surface of the drum can 1 is performed in about 30 seconds.
[0027]
Although not shown, a high voltage cable is connected to each of the coating guns 20a, 20b, and 20c of the coating gun 20 between the control gun and the control gun via the cable. The powder paint is electrostatically charged by the high voltage corona discharge supplied to the coating gun and discharged from the discharge port of each coating gun toward the inner surface of the drum can 1. As a result, the powder coating is applied to the inner surface of the drum 1.
[0028]
During such a painting 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) falls into the painting booth 30 through the opening 1 c of the drum 1, The air is flowing in the painting booth 30 toward the lower side and flows into the powder recovery device 50 below the painting booth 30. The powder that has flowed into the recovery device 50 is captured by the outer peripheral filtration surface of the cylindrical cartridge filter 51 and dropped onto the lower hopper 52, via the powder return hose 13, the cyclone 6, the vibrating screen 7, and the return pipe 8. And returned to the powder supply tank 5.
[0029]
Thus, during the powder coating operation of the drum can 1, the drum can 1 adheres to the bottom 1 b and the inner peripheral wall 1 a of the drum can 1 because the bottom 1 b is located above and the opening 1 c is located below. The powder that has not passed through the opening 1c below the drum can 1 falls to the outside of the drum 1 and does not accumulate on the bottom 1b, and the coating on the bottom 1b becomes thicker than before. There is no. Since the drum 1 is coated while being rotated, the bottom surface 1b is coated over the entire surface, and the inner peripheral surface 1a is coated over the entire circumference. That is, the inner surface of the drum can 1 is coated with a uniform film thickness over the entire surface. Thereby, the quality as a drum can in which inner surface coating was given is stabilized.
[0030]
Further, as described above, the powder that has not adhered to the bottom 1b or the inner wall 1a of the drum can 1 falls into the coating booth 30 outside the drum can through the opening 1c of the drum can 1, and the coating booth 30 below the drum can 1 The powder is recovered by the powder recovery device 50 located at the lower portion thereof, supplied again to the coating gun 20, and used for coating the inner surface of the drum can 1. As a result, the loss of the powder coating is eliminated, and the minimum amount of powder used is reduced to reduce the running cost of the powder coating.
[0031]
Further, in the powder coating method of the present embodiment, while the drum 1 is being coated at the painting work position PA in the center of the painting booth 30, the drum can 1 to be coated next is in the standby position WA. At the opening 31 on the inlet side of the drum can 1 of a certain painting booth 30 and at the opening 31 on the outlet side of the drum can 1 of the painting booth 30 that is the temporary stop position PF of the drum can 1 that has already been painted, the drum can 1 is fishing. Since the position is supported, the amount of air flowing into the painting booth 30 through both the openings 31 and 31 is reduced, and the power consumption of the suction fan is saved. From this point, the powder coating running cost can be reduced.
[0032]
In the powder coating method of the above embodiment, at the start of coating, the coating gun 20 is lifted from the position A and the powder discharge port is placed at the position B close to the bottom 1b of the drum can 1 to coat the inner surface of the drum can 1. The coating gun 20 was gradually lowered toward the opening 1a starting from the bottom 1b side of the drum can 1, but conversely, the coating gun 20 was raised from position A at the start of coating, and the powder discharge port May be placed near the opening 1c of the drum 1 and the inner surface of the drum 1 may be painted from the opening 1c side of the drum 1 and the coating gun 20 is gradually raised toward the bottom 1b. Moreover, the method of performing an inner surface coating combining the operation | movement performed while raising the coating gun 20, and the operation | movement performed while lowering may be sufficient.
[0033]
Moreover, although the case where the bottomed can body is a drum can was shown in the above embodiment, the present invention has another cross-sectional shape that is circular, rectangular, rectangular, polygonal, etc. It can also be applied to shaped cans.
[0034]
【The invention's effect】
As is clear from the above description, the present invention has the following excellent effects.
[0035]
In the structure of Claim 1, the inner surface (bottom and inner peripheral wall) of a bottomed can body can be painted by uniform film thickness. As a result, it is possible to obtain an internally coated can body with stable quality.
[0036]
In the configuration of claim 2, there is no loss of the powder coating material, and the running cost of the powder coating can be reduced as the minimum amount of powder used.
In the configuration of the third aspect, the amount of air flowing into the painting booth through the intake opening and the extraction opening of the painting booth is reduced, and the power consumption of the suction fan is saved. Thereby, powder coating running cost can be further reduced.
[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 diagram showing a coating procedure when a large number of drums are mainly coated sequentially.
FIG. 3 is a schematic longitudinal sectional view illustrating a conventional powder coating method for the inner surface of a drum can.
[Explanation of symbols]
1 drum (bottomed can)
1a Bottom (drum can)
1b Inner wall surface (drum can)
1c Opening (drum can)
2,20 Powder coating guns 20a, 20b, 20c Electrostatic coating gun 5 Powder supply tanks 12a, 12b, 12c Powder supply hose 13 Powder return hose 25 Gun lifting device 30 Coating booth 31 Coating booth opening 32 Overhead conveyor 35 Hanger 40 Workpiece (drum) rotation device 41 Electric motor with reduction gear 42 First winding conduction chain device 43 Second winding conduction chain device 44 Sprocket 50 Powder recovery device 51 Powder recovery cartridge filter PA Coating work position WA Coating Standby position PF Paint finish can pause position

Claims (3)

A powder coating method for coating the inner surface of a bottomed can body by discharging powder from a paint gun, the bottomed can body having an opening with one end closed at the bottom and the other end opened The bottomed can body is hung on a conveyor that runs in the upper part of the painting booth with its bottom up and its opening down , and while rotating the can body, the coating gun is moved to its powder discharge port. It was inserted into the can body from the opening of the lower part of the can body upward, in a state of being positioned the powder discharge opening in the vicinity of the bottom of the can body of the powder from the powder discharge port start the discharge perform painting of the bottom and the inner wall of the rim of the can body, and subsequently discharging the powder from the powder discharge port while gradually lowering the opening direction of the can body painting gun can together they are attached to the inner wall of the body so as to painted, lower the powder not adhered to the can body surface through the opening of the can body It is dropped, further by placing the air flow towards the inside of the painting booth downward by the suction fan, a bottomed powder coating method can body surface, characterized by coating the inner surface of the can body. Furthermore, the powder that did not adhere to the inner surface of the can body mounted on the air flow flowing downward in the coating booth is recovered by flowing into a powder recovery device disposed in the coating booth , and the recovery 2. The powder coating method for an inner surface of a bottomed can body according to claim 1 , wherein the powder is supplied again to the coating gun and used for coating. Furthermore, the opening and taking out of the bottomed can body on the upstream side and the downstream side in the moving direction of the conveyor where the bottomed can body is suspended on both sides of the painting booth. When the bottomed can body is painted in the painting booth with the opening provided, the bottomed can body to be painted next waits at the intake opening position and has already finished painting. 3. The powder coating method for an inner surface of a bottomed can body according to claim 2, wherein the bottomed can body is stopped at the take-out opening position.

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