JP2616071B2 - Can body painting method - Google Patents

Description

The present invention relates to a can body coating method for efficiently coating the inner surface and the outer surface of the bottom of a cylindrical body made of aluminum and the like having a bottom.

`` Conventional technology '' Generally, an aluminum beverage can is composed of a bottomed cylindrical can body obtained by deep drawing and a can lid closing an opening of the can body, and the bottom of the can body is In order to increase the strength against the internal pressure of the can, the central side is formed into a circularly concave dome surface, and the outer peripheral side is formed into a truncated cone-shaped tapered surface (see FIG. 15).

Because of such a shape, it is technically difficult to print and print on the bottom of the aluminum can body,
Until now, only the inner and side surfaces were painted, and the bottom outer surface was used in an unpainted state where the aluminum ground was exposed.

However, in such an aluminum beverage can, when the contents are filled, when exposed to high-temperature water (about 120 ° C.) and subjected to heat sterilization, the aluminum exposed portion on the bottom outer surface is oxidized and blackened, and the appearance is impaired. There is a problem, and contents that can be filled into aluminum beverage cans have been obtained in beverages that do not require high-temperature heat treatment, such as carbonated beverages and beer.

Therefore, recently, in order to expand the use of aluminum beverage cans, there has been a growing demand for aluminum beverage cans in which the outer surface of the bottom of the can body is also provided with a corrosion-resistant coating so that discoloration does not occur even after heat treatment.

"Problems to be Solved by the Invention" By the way, when actually painting the bottom, it is essential to rotate the can body while keeping the position of the bottom of the can body and the spray nozzle accurately, and as a means for that, For example, a method is conceivable in which the axial position is first adjusted by regulating the side surface of the can body, and then the opening end of the can body is brought into contact with some reference guide to perform axial positioning.

However, in this method, if the bottom portion is to be coated immediately after coating the inner surface of the can body, it is possible to prevent the wet paint applied to the open end of the can body from adhering and accumulating on the reference guide. However, there was a drawback in that as the coating was repeated, rotation of the can body was hindered, and the reference guide had to be stopped and the reference guide had to be cleaned.

Further, in order to prevent this drawback, the inner surface must be dried once after the inner surface is coated, and the bottom portion needs to be coated again, which requires two drying steps, which causes a disadvantage that productivity is deteriorated.

"Means for solving the problem" In order to solve the above-mentioned problems, a method for coating a can body of the present invention comprises:
An inner surface coating step of transferring the can body along a transport path, rotating the can body about an axis at a first stop position provided in the transport path, and spraying a paint on an inner surface thereof with a spray gun; The can body is further transferred to the second stop position along the transport path, and at this position, the positioning roller is brought into contact with the outer peripheral side tapered surface at the bottom of the can body to perform axial positioning, and then the side surface of the can body And a bottom coating step of spraying the coating toward the tapered surface and the dome surface of the bottom while rotating the can body about an axis by abutting the driving member to rotate the body. .

[Operation] In this can body coating method, in the bottom coating step, the positioning roller is brought into contact with the outer peripheral tapered surface of the bottom of the can body to perform positioning in the axial direction, and then the driving member is applied to the side surface of the can body. The paint is sprayed toward the tapered surface and the dome surface at the bottom of the can body while rotating the can body around the axis in contact with the can body. At this time, it is not necessary to contact the open end of the can body for positioning. There is no risk of damaging the coating film.

Therefore, the bottom portion can be continuously coated immediately after the inner surface coating, and only one drying step is required after the coating, so that the coating cycle can be shortened and the productivity can be improved.

1 to 3 show a can body coating apparatus for carrying out a can body coating method according to the present invention. FIG. 1 is an overall front view, FIG. 2 is a side view, and FIG. FIG. 3 is a plan view.

First, an outline of the apparatus will be described. In the figure, reference numeral 1 denotes an apparatus base 1 standing upright on a floor surface, and a can body K having a side surface painted from a previous step (not shown) is horizontally laid on an upper front part thereof. A transport feeder 2 for carrying in is installed.

A thick disk-shaped first turntable (part of the transport path) 4 is disposed at a position facing the end of the transport feeder 2, and the first turntable 4 is a drive shaft of a rotary actuator (not shown) in the apparatus base 1. It is fixed and rotated intermittently in the direction of the arrow in the figure every 45 °. On the outer periphery of the first turntable 4, a can body K
Are formed at intervals of 45 °, and the can body K is transferred from the transport feeder 2 to each pocket one by one as the intermittent rotation.

On the side of the first turntable 4, an inner surface painting mechanism 8 having a spray gun 6 is installed so as to face the pocket at the first stop position PA. Paint the entire inner surface of the can body K.

Below the first turntable 4, a second turntable (part of the transport path) having exactly the same shape is disposed adjacent to and along the same plane, and is arranged in the opposite direction to the first turntable 4. It rotates intermittently in synchronization. Thereby, the can body K is sequentially delivered from the pocket of the first turntable 4 to the pocket of the second turntable 10.

Beside this second turntable 10, there is a can body rotating mechanism.
When the second turntable 10 stops, the can body K in the pocket at the bottom coating position (second stop position) P3 rotates around the axis. Also, the can body K at this painting position P3
A bottom coating mechanism 14 is provided on the bottom outer surface side of the container, and sprays paint on the bottom outer surface of the can body K rotated by the can body rotating mechanism 12. And the can body K which finished painting the bottom outer surface is the second
As the turntable 10 rotates, the turntable 10 is sequentially sent out to the next step (not shown) along the unloading guide 16.

Next, the can body rotating mechanism 12 will be described. As shown in FIGS. 4 and 5, on the side of the second turntable 10, a mounting plate 18 is fixed upright to the apparatus base 1.
A pair of side guide plates 20 extending in a semicircular shape along the outer periphery of the second turntable 10 are fixed to each other in parallel. These side guide plates 20 have a length from the introduction position P1 adjacent to the first turntable 4 to the discharge position P4 to the carry-out guide 16, and press the side surface of the can body K to prevent the can body K from dropping out of the pocket.

The mounting plate 18 has a second turntable closer to the second turntable 10 than the side guide plate 20 and closer to the front (closer to FIG. 4) than the open end of the can body K in the pocket.
The arc-shaped nozzle mounting plate 22 extending along the outer periphery of the
It is fixed parallel to the outer periphery of the turntable 10.

At each of the start end, the center, and the end of the nozzle mounting plate 22, an air injection nozzle 24 is vertically penetrated toward the outer peripheral edge of the second turntable 10, and is fixed. Are fixed through a tip fixing plate 26 arranged in parallel with the nozzle mounting plate 22. All of the air injection nozzles 24 are connected to an air supply device (not shown), and are configured to constantly blow hot air.

On the other hand, on the back side of the second turntable 10, a short arc-shaped bottom guide plate 28 is provided at a position facing the pocket at the position P2 in parallel with the second turntable 10,
6 (see FIG. 6).
This bottom guide plate 28 is a can body K in a pocket located at position P2.
To position the can body K in the axial direction. However, it has not reached the bottom painting position P3.

As shown in FIGS. 6 and 7, an arm mounting plate is further fixed to the bottom guide plate 28 through a long hole 32 and a screw, and the position can be changed along the outer periphery of the second turntable 10. ing. An arm 38 is rotatably mounted on the arm mounting plate 34 by an adjusting screw 36.
A positioning roller 40 is provided at the end of the second turntable 10.
It is rotatably mounted toward. The positioning roller 40 has a hemispherical shape, and comes into contact with the outer peripheral portion of the tapered surface KA of the can body K in the pocket located at the bottom coating position P3 as shown in FIG. 6, thereby positioning the can body K in the axial direction. .

As shown in FIGS. 8 and 9, a pair of pulley mounting members 42 are fixed to the mounting plate 18, and each of the pulley mounting members 42 is connected to the axis of the can body K via a bearing 44. A spin shaft 46 is supported so as to be parallel and rotatable. A double pulley 48 and a spin pulley 50 are fixed to the tip of the upper spin shaft 46 at intervals, as shown in FIG. 9, while the tip of the lower spin shaft 46 is also spaced apart from each other. A pair of spin pulleys 50 are fixed apart.

A spin belt (drive member) 52 made of rubber or the like is wound between the pulleys 48 and 50 and 50 and 50 facing each other, and the outer peripheral surfaces of these spin belts 52 are all as shown in FIG. It is in elastic contact with the outer peripheral surface of the can body K in the pocket at the bottom painting position P. The contact pressure of each spin belt 52 with the can body K is set in a range where there is no fear that the outer peripheral surface of the can body K will be dented and there is no risk that the can body K will idle.

As shown in FIG. 9, a rotation detecting plate 54 having a partially cutout 54A on the outer periphery thereof is fixed to the lower spin shaft 46 in the pulley mounting member 42, and faces the outer peripheral surface of the rotation detecting plate 54. Thus, the proximity sensor 56 is fixed. The rotation number of the spin pulley 50 can be detected from a change in the output signal of the proximity sensor 56.

On the other hand, on the side of the mounting plate 18, another mounting plate 58 is fixed to the apparatus base 1 as shown in FIG.
As shown in FIG. 10, pulley shaft 60 and pulley shaft
62 is mounted in parallel with the spin shaft 46 via bearings 64 and 66, respectively.

A pulley 68 is fixed to the upper pulley shaft 60, and a pair of pulleys 70 are fixed to the pulley shaft 62, respectively.
While the timing belt 72 is wound between 68 and 70,
A timing belt 74 is also wound between the pulley 70 and the double pulley 48. Further, a pressing roller 76 for applying tension to the timing belt 74 is rotatably mounted on the mounting plate 58 via a roller shaft 78.

The pulley shaft 60 extends close to the device base 1 and is supported by a bearing 80, and a pulley 82 is fixed to a tip of the pulley shaft 60. on the other hand,
A motor 84 is fixed inside the apparatus base 1, and a timing belt 88 is wound between a pulley 86 fixed to a rotating shaft thereof and the pulley 82.

As shown in FIG. 8, a slide plate 90 is placed on the device base 1 in a direction orthogonal to the timing belt 88.
The timing belt 88 is attached to the slide plate 90.
A pressing roller 92 for pressing the position is mounted so that the position can be adjusted.

Next, the bottom coating mechanism 14 will be described. As shown in FIG. 11, a pair of slide rails 94 are fixed to the apparatus base 1 on the back side of the second turntable 10 in parallel in the vertical direction, and a movable base 96 is provided between the slide rails 94. It is slidably mounted along a slide rail 94.

As shown in FIGS. 12 and 13, a fixed knob 98 is vertically attached to the movable table 96 so as to be movable in the pulling-out direction, and a tip of the fixed knob 98 penetrates the movable table 96 and protrudes rearward. I have.

On the other hand, a fixed plate 100 is attached between the slide rails 94, and the fixed plate 100 has holes through which the tip of the fixed knob 98 can penetrate at each of the position where the movable base 96 is raised and the position where the movable table 96 is lowered. 102 are formed. Thus, the movable base 96 can be raised and lowered by pulling out the fixing knob 98, and the movable base 96 can be fixed at the raised position when painting the bottom outer surface of the can copper K, or at the lowered position when painting is unnecessary. .

A rectangular mounting plate 104 is fixed to the upper end of the moving table 96, and one gun shaft 110, 112 is vertically attached to the mounting plate 104 via two shaft supports 106, 108. It is mounted so that the position can be adjusted. One shaft support 108 is
As shown in FIGS. 15 and 16, an angle changing knob 114 is provided, and by pulling it out, the angle of the gun shaft 112 can be changed.

L-shaped support plates 116 are fixed to the upper ends of the gun shafts 110 and 112, respectively. Further, a mounting plate 118 is fixed to the upper ends of the support plates 116 so as to be rotatable with bolts, and formed on the mounting plates 118. The spray guns 122 and 124 are fixed so as to be position-adjustable by bolts passing through the elongated holes 120 thus formed.

One spray gun 122 has its spray nozzle 122A positioned at the center of the dome surface KB of the can body K in the pocket at the painting position P3.
, And is fixed at a predetermined interval. Further, the other spray gun 124 has the spray nozzle 124A connected to the same can body K.
When the angle changing knob 114 is operated, the direction is changed according to the diameter of the can body K to be painted as shown in FIG. B). The spray guns 122 and 124 are connected to an air supply device and a paint tank (both not shown).

Next, a can body coating method using the above-described coating apparatus will be described.

First, the side-painted can body K supplied from the previous process
Are sequentially fed into the pocket of the first turntable 4 through the transport feeder 2, and the first turntable 4 is rotated to be transferred to the first stop position PA facing the spray gun 6 of the inner surface coating mechanism 8. Next, the spray gun 6 is operated to coat the entire inner surface of the can body K while rotating the can body K in the pocket (above, the inner surface painting step). 2 Feed into the pocket at the introduction position P1 of the turntable 10.

The second turntable 10 is intermittently rotating in synchronization with the first turntable 4, and when the can body K moves from P1 to P2, the inner coating film is dried by hot air blown from the air jet nozzle 24. , Is pushed backward in the pocket, and the bottom outer surface thereof hits the bottom surface guide plate 28 to perform temporary positioning.

Further, when the second turntable 10 is rotated to move the can body to the bottom coating position P3, the positioning roller 40 hits the tapered surface KA to perform axial positioning, and at the same time, two cans are provided on the side surface of the can body K. The spin belt 52 elastically contacts.

In this state, the motors 84 are operated to rotate the respective spin pulleys, and while the can body K is rotated at a high speed by the spin belt 52, the respective spray guns 122 and 124 are operated and the respective spray nozzles 122 are rotated.
The paint is uniformly sprayed from A and 124A onto each of the dome surface KB and the tapered surface KA of the can body K (the above is the bottom coating step).

At this time, the positioning roller 40 is in contact with the tapered surface KA, but it is a point contact, and the roller 40 rotates together with the can body K, and a slight coating film has already been formed on the tapered surface KA at the time of side coating. Therefore, there is no adverse effect such as unapplied paint or adhesion of paint to the roller 40. During the coating, the rotation speed of the rotation detection plate 54 fixed to the spin shaft 46 is determined by a proximity sensor.
After confirming at 56, the motor 84 and the spray guns 122 and 124 are stopped when the predetermined number of revolutions is reached, and the coating conditions are unified.

The can body K having finished painting the inner surface and the bottom outer surface in this way
Is discharged from the second turntable 10 at the discharge position P4,
It is sent to the next drying step along the carry-out guide 16 and is dried with hot air.

According to the above-mentioned can body coating method, the inner surface and the bottom outer surface of the can body K can be efficiently and uniformly coated uniformly, and the can body K which does not cause discoloration or the like even when subjected to a high temperature treatment. Can be produced at low cost.

Further, in this coating method, in the bottom coating step, the tapered surface of the can body K is heated by hot air jetting from the air jet nozzle 24.
The positioning roller 40 is brought into contact with the KA to perform positioning in the axial direction, and the spin roller 52 is brought into contact with the side surface of the can body K to rotate the can body K around the axis. Since the paint is sprayed toward the can, it does not have to contact the open end of the can body K at all, and there is no risk of damaging the coating film at these locations. As a result, the bottom coating can be continuously performed immediately after the inner surface coating, and only one drying step is required after the coating, so that the coating cycle can be shortened, and the cost can be reduced by improving the productivity.

Further, in this coating method, two spin belts 52 are elastically brought into contact with the side surface of the can body K,
Since the can body K is rotationally driven by rotating 52, for example, as compared with a configuration in which a rubber roller or the like is pressed and rotated,
A large contact area with the can body K can be obtained, and even if the contact pressure is small, there is no danger of idling, sufficient driving force can be obtained, and there is no possibility of deformation such as the side surface of the can body K being dented.

Note that the present invention is not limited to the above embodiment, and the configuration may be appropriately changed as needed. For example,
Instead of using a spin belt as a drive member, one or more rubber rollers may be brought into contact with the side surface of the can body, and the rubber body may be rotated to rotate the can body. Instead of being driven to rotate, it may be configured to drive this more positively.

As the can body transport mechanism, not only the turntable 10 but also a configuration in which the can body is fed between a number of aligned rollers can be implemented.

Furthermore, the object of the apparatus of the present invention is not limited to an aluminum can body, and can be applied to any material can body as long as it has a similar shape.

[Effects of the Invention] As described above, according to the can body bottom coating apparatus according to the present invention, in the bottom coating step, the positioning roller is brought into contact with the outer peripheral side tapered surface of the bottom of the can body to position in the axial direction. After that, the driving member is brought into contact with the side surface of the can body to rotate the can body around the axis, and sprays the paint toward the tapered surface and the dome surface at the bottom. It is not necessary to contact the end, and there is no danger of damaging the coating film at these locations and preventing the undried paint from adhering to the device and hindering the painting.

Therefore, bottom coating can be performed continuously immediately after inner coating, and only one drying step is required after coating.
The coating cycle can be shortened, the productivity is high, and it is possible to produce at low cost a can body free from discoloration or the like even when subjected to a high-temperature treatment.

[Brief description of the drawings]

1 to 3 show a can body coating apparatus for carrying out an example of a can body coating method according to the present invention. FIG. 1 is an overall front view, FIG. 2 is a right side view, and FIG. The figure is a plan view. 4 to 16 show the main parts of the apparatus, and FIG.
Fig. 5 is a front view of the can body transport mechanism, Fig. 5 is a view taken along the line VV in Fig. 4, Figs. 6 and 7 are plan and front views of the positioning roller, and Fig. 8 is a can body rotating mechanism. 9 is a side sectional view of the can body rotating mechanism, FIG. 10 is a side view of the can body rotating mechanism, FIG. 11 is a front view of the bottom coating mechanism, and FIG. 12 is a bottom painting. FIG. 13 is a right side view of the mechanism, FIG. 13 is a sectional view taken along the line XIII-XIII in FIG. 12, FIG. 14 is a right side view of the bottom coating mechanism, FIG. 15 is a side view showing a mounting structure of the spray gun, FIG. Is XVI in Fig. 15.
It is a -XVI line view. K: can body, KA: tapered surface, KB: dome surface, 1 ... device base, 2 ... transport feeder, 4 ... first turntable (part of transport path), 6 ... spray Gun 8 Internal coating mechanism 10 Second turntable (part of transport path) 12 Can rotating mechanism 14 Bottom coating mechanism 24 Air jet nozzle 40 Positioning roller , 52: Spin belt (drive member), 122, 124: Spray gun, PA: 1st stop position, P3: Bottom coating position (2nd stop position).

Claims (1)

(57) [Claims] An inner surface coating step of transferring a can body along a conveying path, rotating the can body around an axis at a first stop position provided in the conveying path, and spraying a paint on an inner surface thereof with a spray gun. And transferring the inner-painted can body along the transport path further to the second stop position. At this position, the positioning roller is brought into contact with the outer peripheral side tapered surface at the bottom of the can body to perform axial positioning. And a bottom coating step of spraying paint toward a tapered surface and a dome surface of the bottom while rotating the can body about an axis by abutting a driving member against a side surface of the can body and rotating the driving member. A can body coating method.