JP7293928B2 - METHOD AND APPARATUS FOR INNER SURFACE COATING OF METAL CAN - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method and apparatus for coating the inner surface of a bottomed cylindrical metal can, particularly a metal can having a high height.

Conventionally, the inner surface of the can is protected with a coating to provide corrosion resistance to the contents. In particular, since DI cans are formed by drawing and ironing, they must be painted to protect the inner surface after forming. Spray coating is used for coating the inner surface of this metal can.
The spray coating method includes a fixed gun method and a lancing gun method as spraying means. The fixed gun is mainly used for beverage cans with a relatively low height, and the lancing gun is mainly used for aerosol cans with a high height. The lancing gun method is a method in which the nozzle moves. The nozzle is inserted close to the bottom of the can, and while spraying the paint from the spray hole provided at the tip of the nozzle, it is moved from the bottom toward the open end of the can. is a method of painting the inner surface of the (see, for example, Patent Document 1).
The fixed gun system is a system in which a nozzle is fixed to the outside of the can and sprays from the outside of the can toward the inner surface of the metal can (see, for example, Patent Document 2).
In addition, there are two paint discharge methods: the air spray method, which sprays the paint with the air pressure of compressed air, and the airless spray method, which sprays the paint by directly applying pressure to the paint without using compressed air. In the case of , the air spray method was used because a thick film of high viscosity and high solid content paint was applied.

JP-A-59-196774 JP-A-51-124141

However, with the fixed gun method described in Patent Document 2, in the case of a can with a high height or a can with a narrow opening, the paint may not reach the bottom of the can.
On the other hand, in the case of the lancing gun method described in Patent Document 1, although the paint reaches the bottom of the can even with a high height, the paint is atomized by a compressed air flow, so much mist remains in the air. , It is difficult to adjust the amount of overspray (the amount of the fan-shaped spray pattern that protrudes from the opening edge) on the opening side of the can. occurs. In addition, when neck processing is performed to narrow the opening after the inner surface is coated, the neck is formed in a state where the mist adhering to the outer periphery of the opening protrudes, so there is a problem that wrinkles occur in the neck.
The present invention was made in order to solve the above-mentioned problems, and its object is to allow the bottom and sides of cans with a high height to be sufficiently coated, and to reduce the amount of overspray and mist. To provide a method for coating the inner surface of a metal can and an apparatus for coating the inner surface of the metal can.

In order to achieve the above objects, the present invention provides a method for coating the inner surface of a cylindrical metal can with a bottom, comprising:
A second air spray method in which a nozzle is inserted into the body of the metal can to spray paint with gas pressure on the inner surface of the metal can except for the opening side region of the inner wall of the body. 1 spraying the paint by spraying means to paint,
The opening side area of the body inner wall of the metal can is coated by spraying the paint with a second airless spraying means having a nozzle fixed to the outside of the metal can and spraying the paint with pressure. It is characterized by
According to the present invention, the area other than the opening side area of the body inner wall of the metal can is coated by the movable first spraying means having the air spray type nozzle inserted into the metal can. It is possible to sufficiently coat the bottom and the inner surface of the body even for metal cans with a high viscosity.
On the other hand, the opening side area of the inner wall of the barrel is coated by spraying the paint from the nozzle fixed to the outside of the metal can by the second airless spraying means, so that the amount of overspray can be accurately controlled. The amount of mist can also be reduced.

The method for coating the inner surface of a metal can according to the present invention can be configured as follows.
1. A temporary curing step of heating and temporarily curing after coating at least the bottom side region of the region other than the opening side region of the body inner wall of the metal can,
After the temporary hardening step, the opening side region of the inner wall of the body portion is painted.
By doing so, it is possible to prevent the paint from dripping.
2. After the bottom portion of the metal can is also coated together with the bottom portion side region of the inner wall of the body portion, the pre-curing step is performed.
The number of steps can be reduced by painting the bottom as well.
3. The coating of the bottom portion of the metal can is performed after the temporary curing step.
By forming the bottom portion in a separate process, the thickness of the coating film on the bottom portion can be accurately formed.
4. Different types of paints are used for the paint used to coat the opening-side area of the body inner wall of the metal can and the paint used to paint areas other than the opening-side area.
When processing the opening, it is possible to select a coating that is suitable for processing and has a soft coating film after heat curing.

In addition, the inner surface coating apparatus for metal cans of the present invention is an inner surface coating apparatus for metal cans for coating by spraying paint on the inner surface of a cylindrical metal can with a bottom,
A second air spray method in which a nozzle is inserted into the body of the metal can to spray paint with gas pressure on the inner surface of the metal can except for the opening side region of the inner wall of the body. 1 spraying means;
a second spraying means of an airless spray type that sprays the opening side area of the body inner wall of the metal can with a nozzle fixed to the outside of the metal can with pressure applied to the paint. Characterized by
According to the present invention, the area other than the opening side area of the inner side wall of the body is coated by spraying means having a nozzle inserted into the body. can be painted on.
On the other hand, the area near the open end of the inner circumference of the barrel is painted with an airless spray nozzle placed outside the metal can, so the amount of overspray can be controlled with high precision and the amount of mist can be reduced. .

The apparatus for coating the inner surface of metal cans according to the present invention can be configured as follows.
1. A conveying means is provided for sequentially conveying the metal cans along a conveying path, and the conveying path is provided with a first coating station in which the spraying means having the first spraying means is arranged, and the second spraying means are arranged. having a second painting station where the
The first coating station coats at least the bottom side area of the body inner wall, and the second coating station coats the opening side area.
2. The second coating station further includes a first spraying means together with the second spraying means. An additionally arranged first spray means coats the bottom of the inner surface of the can. 3. Between the first coating station and the second coating station, there is provided a temporary curing processing section that heats and temporarily cures the coating film.

As described above, according to the present invention, the bottom and the inner surface of the body can be sufficiently coated even with a tall can, and the amount of overspray and the amount of mist can be reduced.

FIG. 1 is a side view showing the configuration of a conveying path of an apparatus for coating the inner surface of metal cans according to Embodiment 1 of the present invention. 2(A) is a conceptual diagram showing the configuration of the movable gun in FIG. 1, (B) is a schematic diagram showing the cam structure of the movable gun, and (C) is a conceptual diagram showing the configuration of the fixed gun in FIG. FIG. 3 is a conceptual diagram showing a piping system of a movable gun and a fixed gun in FIG. 2; 4A to 4E are diagrams showing the coating process of the apparatus of FIG. 1; FIG. FIG. 5 is a side view showing the configuration of a conveying path of the apparatus for coating the inner surface of metal cans according to Embodiment 2 of the present invention. 6A to 6E are diagrams showing the coating process of the apparatus of FIG. 5; FIG.

The present invention will be described in detail below based on the illustrated embodiments.
The dimensions, materials, shapes, and relative arrangement of the components described in the following embodiments should be changed as appropriate according to the configuration of the device to which the invention is applied and various conditions, and the scope of the invention is not limited. It is not intended to be limited to the following embodiments.
[Embodiment 1]
FIG. 1 is a diagram showing a schematic configuration of a conveying path of an apparatus for coating the inner surface of metal cans according to Embodiment 1 of the present invention.
The conveying mechanism is of a rotary type, and the metal cans 1 are intermittently conveyed at predetermined intervals by the rotation of the turret (conveying means) 100 so as to revolve around the rotation axis N of the turret 100. be. The metal can 1 is conveyed while being held by the can holder 110 . In FIG. 1, the turret 100 is schematically represented by a circle, and has a recess (not shown) that engages with the can holder 110 to hold the can holder 110 in the recess. It is configured to be conveyed in the circumferential direction.
The turret 100 has its rotational axis N oriented horizontally, and the metal can 1 is conveyed while rotating in the vertical direction. On one side (left side in FIG. 1) of the transport path across a vertical line V passing through the rotation axis N of the turret 100, there is an entrance 101 through which uncoated metal cans are carried in, and first coating stations A1 and A2. is provided on the other side (right side in FIG. 1) with second coating stations B1 and B2 and an outlet 102 for carrying out metal cans that have been subjected to the coating process. A path W2 is configured, and the first transport path W1 and the second transport path W2 are continuously connected by a detour transport path W3 to a temporary hardening section C provided at a location separated from the turret 100 above. A preheater is provided in the temporary hardening processing section C. As shown in FIG.
The first painting stations A1 and A2 are arranged at stop positions adjacent to each other in the conveying direction, and each have an air spray nozzle 11 inserted into the body portion 1a of the metal can 1 to spray the paint with gas pressure. A moving gun 10, which is an air spray type first spraying means, is arranged. The movable gun 10 coats a region of the inner surface of the metal can 1 other than the opening side region 1b1 of the body inner wall 1b, which is the bottom region 1b2 and the bottom 1c of the body inner wall 1b in this embodiment. In this example, separate metal cans 1 are simultaneously coated at the first coating station A1 on the upstream side and the first coating station A2 on the downstream side. sent. Therefore, each metal can 1 is coated once at the first coating station A1, A2.
The second coating stations B1 and B2 are provided with a fixed gun 20 as a second spraying means having an airless spray type airless spray nozzle 21 for spraying the paint with pressure. This fixed gun 20 coats the opening side region 1b1 of the body inner wall 1b. In this case also, separate metal cans 1 are coated simultaneously at the upstream second coating station B1 and the downstream second coating station B2, and are intermittently fed two cans at a time. A duct 103 for sucking paint mist during painting is provided near the first painting stations A1, A2 and the second painting stations B1, B2.

Next, the movable gun 10 and the stationary gun 20 will be described with reference to FIG.
The mobile gun 10 is shown in FIG. 2(A).
The movable gun 10 has an air spray nozzle 11 having a spray hole 11 a at its tip, and a main body 12 provided at the base end of the air spray nozzle 11 . The main body 12 is provided with an air supply pipe 13 to which compressed air is supplied and a paint supply pipe 14 to which paint is supplied. A paint return pipe 14a for returning the paint to a paint tank, which will be described later, is connected to the main body 12. As shown in FIG. An air return pipe 13a is also provided.
The hole axis of the spray hole 11a at the tip of the nozzle is inclined by a predetermined angle α1 with respect to the can axis M, and the spray angle β1 of the spray pattern T1 fan-shaped from the spray hole 11a is the same as the bottom 1c at the spray start position. It is configured to cover both the body inner wall 1b, and is set so that both the bottom 1c and the body inner wall 1b are coated.
The movable gun 10 is supported by a guide device (not shown) so as to be reciprocally movable in the axial direction of the air spray nozzle 11 , and is reciprocally driven by a driving device 15 . The driving device 15 can be composed of, for example, a cam 16 as shown in FIG. 2B and a motor 17 that drives the cam 16 to rotate. By rotating the cam 16 by the motor 17, the movable gun 10 reciprocates between the forward limit position and the backward limit position. The forward limit position is a position where the air spray nozzle 11 is inserted into the metal can 1 and the tip faces the bottom portion 1c of the metal can 1, and the backward limit position is a withdrawal position where the air spray nozzle 11 is pulled out of the opening to the outside. .
The drive device 15 is not limited to a cam mechanism, and may be a feed screw mechanism such as a ball screw, a gear mechanism such as a rack and pinion, or any other mechanism that converts rotary motion into linear motion, or a mechanism that linearly drives with a linear motor. etc., various driving devices can be employed.

The fixed gun 20 is shown in FIG. 2(C).
The fixed gun 20 has a short airless spray nozzle 21 having a spray hole 21a at its tip, and a main body 22 provided at the base end of the airless spray nozzle 21. The main body 22 is a device (not shown). is fixed to the frame of the A paint supply pipe 24 for supplying paint and a paint return pipe 25 for returning the paint to a paint tank, which will be described later, are connected to the main body 22 .
The hole axis of the spray hole 21a at the tip of the nozzle is inclined by a predetermined angle α2 with respect to the can axis. It is set so as to adhere to the opening side region 1b1 of 1b, that is, the range extending from the opening end to the bottom by a predetermined distance. The range of the opening side region is preferably, for example, a range up to about ⅓ of the can height. The spray pattern T2 is set so as to slightly cross the boundary between the opening side region 1b1 and the bottom side region 1b2 and partially cover the coating film formed by the moving gun 10. A coating film is formed continuously.
In addition, the end of the spray pattern T2 on the opening end side is set to coincide with the opening end of the can so that the amount of overspray is minimized.

FIG. 3 shows a simple plumbing diagram of the moving gun 10 and the fixed gun 20. As shown in FIG.
The piping system of the movable gun 10 is provided with a paint supply passage 31 from a paint tank 30 to the movable gun 10. The paint supply passage 31 is provided with a pump 32 and a regulator 34 for maintaining a constant pressure introduced from the pump 32. is provided.
Further, an air pressure supply passage 37 is provided to supply compressed air from an air pressure source 36 to the movable gun 10, the compressed air is supplied to the movable gun 10, and air pressure is supplied by a control valve (not shown) to spray paint. be done.
Also, the pump 32 is a pump operated by air pressure from the air pressure source 36, but the type of pump is not particularly limited. Further, a return passage 33 is provided for returning the paint from the moving gun 10 to the paint tank 30, so that the paint is circulated.
On the other hand, the piping system of the fixed gun 20 is provided with a paint supply passage 41 extending from the paint tank 40 to the fixed gun 20. The paint supply passage 41 is provided with a pump 42 and a regulator for keeping the pressure introduced from the pump 42 constant. 44 are provided. A regulator 44 maintains a pressure higher than the introduction pressure to the moving gun 10 . The fixed gun 20 is also provided with a return passage 43 for returning the paint to the paint tank 40, so that the paint is circulated.

Next, the inner surface coating of a metal can using the apparatus for coating the inner surface of a metal can will be described with reference to FIG. 4(A) and (B) show the painting process in the first painting station in FIG. 1, FIG. 4(C) shows the state in the temporary hardening section in FIG. 1, and FIG. 4(D). , (E) show the coating process at the second coating station in FIG.
In FIG. 1, a large number of metal cans 1 are held on the conveying path, and each coating process is performed simultaneously at each coating station. The processing will be explained sequentially.

First painting station A1, A2
The metal cans 1 are intermittently fed two by two, and the uncoated metal cans 1 are conveyed to the first coating station A1 on the upstream side and the first coating station A2 on the downstream side. Since the coating process is the same for all stations, only the first coating station A1 on the upstream side will be described. When the metal can 1 reaches the first coating station A1, the air spray nozzle 11 of the moving gun 10 is inserted from the open end of the metal can into the interior, stops at a predetermined position, and starts spraying paint (Fig. 4 (A) )reference). The coating is performed by rotating the metal can 1 around the can axis M by a known method, moving the air spray nozzle 11 in the direction of pulling out from the metal can, and spraying up to the boundary position with the predetermined opening area ( See FIG. 4(B)). Thereby, the coating film S1 is formed on the bottom portion 1c and the bottom portion side region 1b2.
Spraying is stopped at this position, and the withdrawal operation of the air spray nozzle 11 is continued to separate the tip of the air spray nozzle 11 from the open end of the metal can 1 to the outside.
Next, the turret 100 is intermittently driven two by two, and the metal cans 1 coated in the first coating station A1 on the upstream side and the first coating station A2 on the downstream side are intermittently fed toward the pre-hardening treatment section C. go.

The detour conveying path W3 is a path detouring from the turret 100 to the pre-curing treatment section C. During a plurality of intermittent feeding steps, the detour conveying path W3 is moved, heated by the preheater, and formed into the bottom portion 1c and the bottom side region 1b2. The formed coating film S1 is temporarily cured (see FIG. 4(C)). In the temporary curing section C, for example, heat treatment is performed using a hot air oven. The heating temperature of the hot air oven is 50 to 150° C., and the heating time is about 5 to 120 seconds.

Second painting station B1, B2
The metal cans 1 that have passed through the temporary hardening treatment section C enter the second conveying path W2 and are intermittently fed two cans at a time to reach the second coating station B1 on the upstream side and the second coating station B2 on the downstream side. Since the coating process is the same in both the second coating stations B1 and B2, the second coating station B1 on the upstream side will be described.
In this second coating station B1, as shown in FIG. 4(D), the stationary gun 20 is actuated to spray the paint from the spray holes 21a of the airless spray nozzles 21, and the inside wall of the body portion of the rotating metal can 1 is sprayed. Paint is sprayed on the opening side region 1b1 of 1b. The paint spray pattern T2 of this airless spray has little mist, and the fine droplets of the paint are within the range of the spray pattern T2, so the amount of overspray can be accurately controlled and the amount of mist can be reduced. can. The range where the spray pattern T2 adheres partially overlaps the bottom side region 1b2 of the trunk inner wall 1b, and the boundary is also sprayed uniformly. Spraying is stopped after a predetermined time has elapsed. As a result, a uniform coating film S2 is formed on the opening side region 1b1 of the body inner wall 1b, and the coating of the inner surface is finished (FIG. 4(E)).
After the inner surface coating is finished, the metal can 1 advances along the second conveying path W2 by intermittent driving of the turret 100, and after being intermittently driven several times, is carried out from the outlet 102, and is transferred to the next process, for example, the main curing process. , and the coating is completely baked.

[Embodiment 2]
Next, Embodiment 2 of the present invention will be described with reference to FIGS. 5 and 6. FIG.
In the following description, points different from the first embodiment will be mainly described, and the same reference numerals will be assigned to the same configurations as in the first embodiment, and description thereof will be omitted.
FIG. 5 shows an apparatus for coating the inner surface of metal cans according to a second embodiment.
In the first embodiment, only the movable guns 10 with the air spray nozzles 11 are arranged at the first painting stations A1 and A2, and only the fixed guns 20 with the airless spray nozzles 21 are arranged at the second painting stations B1 and B2. However, in the second embodiment, a fixed gun 20 with an airless spray nozzle 21 and a movable gun 10C with an air spray nozzle 11 are added to the second coating stations B1 and B2. differ in
In Embodiment 2, the coating film is formed only on the bottom side region 1b2 of the inner circumference of the can body by the moving guns 10B of the first coating stations A1 and A2, out of the region other than the opening side region 1b1 of the inner surface of the can. The moving guns 10C of the coating stations B1 and B2 apply spray coating to the bottom portion 1c. Here, the movable guns 10B and 10C have the same configuration as the movable gun 10 of the first embodiment, but the coating film forming positions are different, and the spray patterns and the like are different. C is attached for distinction.

Hereinafter, the coating processes at the first coating stations A1, A2 and the second coating stations B1, B2 in the second embodiment will be described with reference to FIG.
First painting station A1, A2
When the metal can 1 reaches the first coating station A1 on the upstream side, the air spray nozzle 11 of the moving gun 10B is inserted into the metal can 1 from the open end, stops at a predetermined position, and rotates the metal can 1. while spraying paint (see FIG. 6(A)).
The spray pattern T1 that spreads from the spray hole 11a of the movable gun 10 has a range that mainly covers the inner peripheral surface of the barrel at the spray start position. Then, the air spray nozzle 11 is moved in the direction of separating from the metal can, spraying up to the boundary position with the predetermined opening region (see FIG. 6B), and spraying is stopped. As a result, a coating film S1b is formed on the bottom side region 1b2 of the inner wall of the trunk portion. After the spraying is stopped, the air spray nozzle 11 is further moved to separate the tip of the air spray nozzle 11 from the open end of the metal can 1 to the outside.
Next, it moves to the bypass conveying path W3 and is heated by the preheater to temporarily cure the coating film S1b formed on the bottom side region 1b2 of the inner surface of the body (see FIG. 6C).

Second painting station B1, B2
In the second coating stations B1 and B2, as shown in FIG. 6(D), the opening side region 1b1 is coated by the fixed gun 20, and as shown in FIG. It is different from the first embodiment in that it is painted by air spray. A coating film S2 is formed on the opening side region 1b1, and a coating film S1c is formed on the bottom portion 1c, so that a uniform coating film is formed on the entire inner surface. In the drawing, the painting is performed first by the stationary gun 20, but the painting by the movable gun 10C may be performed first.
By separating the coating of the bottom portion 1c and the coating of the bottom portion side region 1b2 of the inner wall of the body portion in this way, the coating film S1c on the bottom portion can be made more uniform.
When the coating at the second coating stations B1 and B2 is completed, the turret 100 is intermittently driven to carry out from the outlet 102 and proceed to the next process.

[Other embodiments]
- Types of metal cans Metal cans to which the present invention can be applied include not only aerosol cans, but also various metal cans such as beverage cans and screwed metal cans (so-called bottle cans). In addition, it can be widely applied to the inner surface coating of two-piece bottomed cylindrical empty cans such as DI cans and deep drawn cans that are drawn and ironed, and the inner surface coating of bottomed cylindrical empty three-piece cans. .
Regarding Order and Number of Painting Guns 10 and Fixed Guns 20 In Embodiment 2, the movable guns 10C for painting the bottom portion 1c may be arranged in the first painting stations A1 and A2. That is, it is possible to arrange two moving guns 10B and 10C in the first coating stations A1 and A2. Further, the number of movable guns 10 is not limited to two, and a plurality of movable guns can be provided. Also, the number of fixed guns 20 is not limited to one, and a plurality of fixed guns may be provided.
Further, in Embodiments 1 and 2, the fixed gun 20 for coating the opening side region 1b1 of the inner wall of the body portion of the metal can 1 is arranged in the second coating stations B1 and B2 as a post-process. It may be arranged in stations A1 and A2 so that the opening-side region 1b1 of the inner wall 1b of the body portion is coated first.
・About the paint In the first and second embodiments, the same paint is applied to the opening side region 1b1 of the can body inner wall and the other regions, but different paints are applied. may
For example, in the case of aerosol cans and the like, a hard paint film after baking is used for the inner wall of the can body in consideration of corrosion resistance (a soft paint film is inferior in corrosion resistance). On the other hand, in the aerosol can, since the mounting cup is attached to the opening end of the metal can, the opening side region of the can body requires a large amount of processing, and the opening side region 1b1 of the body inner wall 1b of the metal can requires a large amount of processing. It is preferable to use a paint that has a soft coating film after baking that can withstand high processing.
Polyamide-imide, epoxyphenol, etc., can be used as coatings with a hard coating film, and polyester amino, epoxyphenol, etc. with a small amount of curing agent can be used as coatings with a soft coating film.
-Others In the first and second embodiments, the turret 100 is used to rotate the conveying path of the metal cans, but the chain may be linearly moved.

Reference Signs List 1 metal can 1a barrel 1b barrel inner wall 1b1 opening side region 1b2 bottom side region 1c bottoms 10, 10B, 10C moving gun 11 air spray nozzle 11a spray hole 12 main body 13 air supply pipe 13a air return pipe, 14 paint supply pipe,
14a Paint return pipe 15 Drive device 16 Cam 17 Motor 20 Fixed gun 21 Airless spray nozzle 21a Spray hole 22 Main body 24 Paint supply pipe 25 Paint return pipe 30 Paint tank
31 paint supply channel, 32 pump, 33 return channel,
34 regulator, 36 air pressure source, 37 air pressure supply path 40 paint tank 41 paint supply path, 42 pump, 43 return flow path 44 regulator 100 turret,
101 inlet, 102 outlet, 103 duct 110 can holders A1, A2 first coating station B1, B2 second coating station C pre-curing unit N rotary shaft M can shaft S1 coating film (bottom side region 1b2 and bottom portion 1c)
S1b, S1c coating film (bottom side region 1b2, bottom 1c)
S2 coating film (opening side region 1b1)
T1, T1b, T1c spray pattern (air spray of moving guns 10, 10B, 10C),
α1 angle of spray hole axis to can axis, β1 spray angle T2 spray pattern (airless spray of fixed gun 20)
α2 angle of spray hole axis with respect to can axis, β2 spraying angle V vertical line, W1 first conveying path, W2 second conveying path W3 detour conveying path

Claims (9)

In a method for coating the inner surface of a metal can in which the inner surface of a cylindrical metal can with a bottom is sprayed with a spraying means,
A first air spray method for spraying paint with gas pressure on the inner surface of the metal can except for the opening side area of the inner wall of the metal can, and having a nozzle inserted into the body of the metal can. Spraying and painting the paint by spraying means,
The opening side area of the body inner wall of the metal can is coated by spraying the paint by a second airless spraying means having a nozzle fixed to the outside of the metal can and spraying the paint with pressure applied. A method for coating the inner surface of a metal can, characterized by: A temporary curing step of heating and temporarily curing after coating at least the bottom side region of the region other than the opening side region of the body inner wall of the metal can,
2. The method for coating the inner surface of a metal can according to claim 1, wherein the opening side region of the inner wall of the body portion is coated after the temporary hardening step. 3. The method of coating the inner surface of a metal can according to claim 2, wherein the temporary hardening step is performed after the bottom portion of the metal can is also coated together with the bottom portion side region of the inner wall of the body portion. 3. The method for coating the inner surface of a metal can according to claim 2, wherein the coating of the bottom portion of the metal can is performed after the temporary curing step. 5. The metal according to any one of claims 1 to 4, wherein the paint for coating the opening side area of the body inner wall of the metal can and the paint for coating areas other than the opening side area are different kinds of paint. A method of painting the inner surface of a can. In a metal can inner surface coating apparatus for coating by spraying paint on the inner surface of a bottomed cylindrical metal can,
A first air spray method for spraying paint with gas pressure on the inner surface of the metal can except for the opening side area of the inner wall of the metal can, and having a nozzle inserted into the body of the metal can. a spraying means;
a second spraying means of an airless spray type that sprays the opening side area of the body inner wall of the metal can with a nozzle fixed to the outside of the metal can with pressure applied to the paint. A device for coating the inner surface of a metal can. A conveying means is provided for sequentially conveying the metal cans along a conveying path, and the conveying path is provided with a first coating station in which the spraying means having the first spraying means is arranged, and the second spraying means are arranged. having a second painting station where the
7. The apparatus for coating the inner surface of metal cans according to claim 6, wherein the first coating station coats at least the bottom side region of the body inner wall, and the second coating station coats the opening side region. The second coating station further includes a first spraying means together with the second spraying means. 8. The apparatus for coating the inner surface of metal cans according to claim 7, wherein the bottom portion of the inner surface of the can is coated by the additionally arranged first spray means. 9. The apparatus for coating the inner surface of metal cans according to claim 7, further comprising a temporary hardening unit for heat-treating and temporarily hardening the coating film between the first coating station and the second coating station.

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