COATING METHOD AND COATING DEVICE

Provided are a coating method and a coating device capable of making the coating film thickness of a coating agent uniform with a simple structure. Provided is a coating method, the coating; method including moving a spray gun (20) and the container (C) relative to each other to insert the spray gun (20) into the container (C), and ejecting the coating agent onto the container inner wall surface from the spray gun while adjusting a relative positional relationship between the spray gun (20) and the container (C) in the gun longitudinal direction, rotating the spray gun (20) and the container (C) relative to each other about an axis along the gun longitudinal direction, and changing at least one of a relative rotation speed between the spray gun (20) and the container (C) and an angle range of the rotation in accordance with the shape of the container (C).

TECHNICAL FIELD

The present invention relates to a coating method and a coating device for coating a container inner wall surface with a coating agent, and in particular relates to a coating method and a coating device for coating the container inner wall surface with a coating agent that improves slidability.

BACKGROUND ART

In general, a plastic container is easy to form and can be manufactured inexpensively, and hence the plastic container is used widely for various purposes. However, in the case where viscous contents such as a mayonnaise-like food are injected into the container, the contents easily adhere to a container inner wall surface, and hence there has been a problem that it is difficult to use up the contents without leaving the contents in the container. To cope with this, development of a coating agent that improves slidability of the contents is promoted in recent years and, it is known that, in the case where the container inner wall surface is coated with such a coating agent, the slidability of the container inner wall surface is improved, and the contents in the container can be easily used up.

In order to exert the performance of such a coating agent adequately, it is necessary to uniformly coat the container inner wall surface with the coating agent. However, the shape of the plastic container varies widely and the diameter of the opening of the plastic container is small, and hence there has been a problem that, in the case where a commonly used spray gun (see, e.g., Patent Literature 1) is used as a coating device, it is difficult to uniformly coat the container inner wall surface with the coating agent.

To cope with this, in Japanese Patent Application No. 2014-87331, the applicant has proposed, as the coating device that solves the above problem, the coating device including a spray gun that has a spray nozzle capable of electing the coating agent, a rotary driver for rotating the spray gun about an axis along a gun longitudinal direction, and a mover for moving the spray gun along the gun longitudinal direction.

In the coating device described in Japanese Patent Application No. 2014-87331, the entire container inner wall surface is coated with the coating agent by inserting the spray gun into the container, and ejecting the coating agent from the spray nozzle while rotating the spray gun about the axis along the gun longitudinal direction and, at the same time, moving the spray gun up and down or back and forth.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Patent Application Publication No. 2001-224988

SUMMARY OF INVENTION

Technical Problem

In the case where the container inner wall surface is coated with, the above-described coating agent that improves the slidability of the contents, when the coating film thickness of the coating agent becomes uneven, the slidability of the container inner wail surface is reduced. Accordingly, required accuracy in the uniformity of the coating film thickness of the coating agent is high.

In this regard, the coating device described in Japanese Patent Application No. 2014-87331 is capable of coating the entire container inner wall surface with the coating agent but, in the case where a container having a special shape such as a mayonnaise bottle in which the diameter of a body on the side of an opening is small is a coating target, the coating device has a problem that the coating film thickness of the coating agent on the container inner wall surface becomes uneven. That is, in the coating device, the ejection amount of the coating agent from the spray nozzle per unit time is constant and, in the case where the container such as the mayonnaise bottle in which a distance from the position of the spray nozzle to the container inner wall surface is not uniform is the coating target, the coating film thickness of the coating agent becomes uneven depending on the area of the container inner wall surface.

To cope with this, the present invention solves these problems, and an object thereof is to provide a coating method and the coating device capable of making the coating film thickness of the coating agent uniform with a simple structure even in the case where the container having the special shape is the coating target.

Solution to Problem

A coating method of the present invention is a coating method for coating, a container inner wall surface with a coating agent, the coating method including moving a spray gun that ejects the coating agent and a container relative to each other along a gun longitudinal direction to insert the spray gun into the container, and ejecting the coating agent onto the container inner wall surface from the spray gun while adjusting a relative positional relationship between the spray gun and the container in the gun longitudinal direction, rotating the spray gun and the container relative to each other about an axis along the gun longitudinal direction, and changing at least one of a relative rotation speed between the spray gun and the container and an angle range of the rotation in accordance with a shape of the container, whereby the above problems are solved.

In addition, a coating device of the present invention is a coating device for coating a container inner wall surface with a coating agent, the coating device including a spray gun that ejects the coating agent, a rotary driver that rotates the spray gun about an axis along a gun longitudinal direction, and a mover that moves the spray gun along the gun longitudinal direction, wherein the rotary driver has a rotation control section that changes at least one of a rotation speed and a rotation angle range of the spray gun, whereby the above problems are solved.

Advantageous Effects of Invention

According to first, second, third, sixth, and seventh aspects of the present invention, it is possible to make the coating film thickness of the coating agent uniform with a simple structure even in the case where the container having a special shape is a coating target by changing at least one of the relative rotation speed between the spray gun and the container and the angle range of the rotation in accordance with the shape of the container, i.e., a distance from the position of a spray nozzle to the container inner wall surface when the coating agent is ejected from the spray gun.

In addition, in the case where a configuration is adopted in which the container is held so as not to rotate and the spray gun is rotated, it is not necessary to install a rotation device of the container in an existing manufacturing line, it is possible to efficiently perform the coating of the coating agent in limited space in the manufacturing line, and it is easy to reliably hold the container even in the case where the container has the special shape.

According to fourth and eighth aspects of the present invention, it is possible to make the coating film thickness of the coating agent uniform with the simple structure even in the case where the container having a special shape such as a mayonnaise bottle in which a cross-sectional shape changes along a container height direction is the coating target by changing at least one of the relative rotation speed between the spray gun and the container and the angle range of the rotation at each set position at which the spray gun is stopped by moving the spray gun intermittently such that the spray gun is stopped at a plurality of the set positions in the gun longitudinal direction.

According to fifth and ninth aspects of the present invention, it is possible to prevent an atomized coating agent from adhering to unplanned portions such as the upper end edge of a container mouth, the spray nozzle, and an external environment, and make the coating film thickness of the coating agent uniform by causing an aspirator to face the container mouth and suck the coating agent atomized in the container during or after the ejection of the coating agent from the spray gun.

REFERENCE SIGNS LIST

23Coating agent ejection path

24Coating agent passage

31Coating agent passage

32Elastic shape section

34Coating agent passage

35Elastic shape section

40Coating agent circulation path

52Air supply pipe

101Air flow amplification flow path section

102Gas supply section

105Gas supply pipe

C Container

L Coating agent

A Air

Description of Embodiments

Hereinbelow, a coating device10according to Embodiment 1 of the present invention will be described based on the drawings.

As shown inFIGS. 1 and 2, the coating device10coats the inner wall surface of a container C that contains viscous contents such as a mayonnaise-like food with a coating agent L that improves slidability of the contents by inserting a spray nozzle22into the container C first, and ejecting the coating agent L from the spray nozzle22while rotating a spray gun20in the container C.

As shown inFIGS. 1 to 3, the coating device10includes the spray gun20that has a coating agent ejection path23, an outward pipe30and a return pipe33that are mounted to the spray gun20and constitute a coating agent circulation path40, a supply controller50for controlling the supply of the coating agent L to the coating agent ejection path23from the coating agent circulation path40, a rotary driver60for rotating the spray gun20about an axis along a gun longitudinal direction, a mover70for moving the spray gun20along the gun longitudinal direction, a rotation supporter80that has bearings81that rotatably support the spray gun20, and a container holder90for holding the container C.

Hereinbelow, each component of the coating device10will be described based onFIGS. 1 to 3.

First, as shown inFIGS. 1 to 3, the spray gun20ejects the coating agent L, and has a shaft21that can be inserted into the container C, and the spray nozzle22that is provided at the tip of the shaft21. Herein, the nozzle shape of the spray nozzle22may be any shape as long as the nozzle shape causes the spray nozzle22to eject the coating agent L such that the coating agent L is spread, and the nozzle shape that causes the spray nozzle22to eject the coating agent L such that the coating agent L is spread symmetrically is preferable. In addition, one spray nozzle22is provided at the tip of the shaft21in the present embodiment, but the number of spray nozzles22and the position of the spray nozzle22may be any number and any position, and an air ejection port maybe provided in the spray nozzle22in order to atomize the coating agent L ejected from the spray nozzle22.

As shown inFIG. 3, inside the spray gun20, the coating agent ejection path23that communicates with the spray nozzle22, and a coating agent passage24that communicates with the coating agent ejection path23are formed. The coating agent passage24constitutes the coating agent circulation path40that circulates the coating agent L together with a coating agent passage31in the outward pipe30and a coating agent passage34in the return pipe33.

As shown inFIG. 1, the outward pipe30and the return pipe33are disposed outside the spray gun20, one end of each of the outward pipe30and the return pipe33is mounted to the outer peripheral surface of the spray gun20, and the other end thereof is mounted to a tank (not shown) in which the coating agent L is stored. The outward pipe30and the return pipe33are formed of hard synthetic resin such as high-density polyethylene so as to bear the pressure of the coating agent L that circulates in the coating agent passages31and34formed inside the outward pipe30and the return pipe33. As shown inFIG. 1, in the outward pipe30and the return pipe33, coil-shaped elastic shape sections32and35are formed.

As can be seen fromFIG. 3, the supply controller50has a valve51that is provided between the coating agent ejection path23and the coating agent circulation path40and can be opened and closed, an air supply pipe52that constitutes air ejection means for supplying air for opening and closing the valve51, and an air supply source (not shown) that is connected to the air supply pipe52. The valve51is opened by supplying air to the spray gun20through the air supply pipe52, and the coating agent L is supplied to the coating agent ejection path23from the coating agent circulation path40by using the pressure of the coating agent L in the coating agent circulation path40. Thus, in the present embodiment, the ejection timing and the ejection amount of the coating agent L from the spray nozzle22are controlled by the timing and the time of the air supply.

Note that the specific configuration of the supply controller50may be any configuration as long as the configuration controls the supply of the coating agent L to the coating agent ejection path23from the coating agent circulation path40, and the drive source of the supply controller50may also be any drive source such as a drive source that uses electric power, in addition to the above-described drive source that uses air.

As shown inFIG. 2, the rotary driver60has a stepping motor61that rotationally drives the spray gun20, and a motor coupling62that couples the output shaft of the stepping motor61to the upper end of the spray gun20.

The stepping motor61is controlled by a PLC or the like, and its rotation speed and rotation angle range can be set arbitrarily. In the present embodiment, the stepping motor61functions as a rotation control section capable of changing at least one of the rotation speed and the rotation angle range of the spray gun20.

Note that the specific configuration of the rotation control section is not limited to the above-described stepping motor, and the specific configuration thereof may be any configuration as long as the configuration is capable of changing at least one of the rotation speed and the rotation angle range of the spray gun20. For example, a servo motor may be used instead of the stepping motor

61, and the rotation speed may be controlled by connecting a speed controller capable of controlling the flow rate of supplied air to an air rotary actuator.

As shown in.FIG. 2, the mover70is constituted by a moving section71that is movable along an up-and-down direction, a base72that supports the moving section71such that the moving section71is movable in the up-and-down direction, and a stepping motor73that drives the moving section71. The mover70moves the moving section71in the up-and-down direction by converting the rotation of the stepping motor73into linear motion with a ball screw, a rack and pinion, and the like. The stepping motor61, the rotation supporter80, and the like are fixed to the moving section71.

The stepping motor73is controlled by the PLC or the like, and its rotation speed, rotation angle range and the like can be set arbitrarily. In the present embodiment, the stepping motor73functions as a position control section capable of stopping the spray gun20at a plurality of set positions in the gun longitudinal direction.

Note that the specific configuration of the position control section is not limited to the above-described stepping motor, and the specific configuration thereof may be any configuration as long as the configuration is capable of stopping the spray gun20at the plurality of set positions in the gun longitudinal direction. For example, the servomotor may be used instead of the stepping motor61.

The container holder90is provided such that the container bolder90is movable in a horizontal direction, is configured to hold the container C in a fixed state, and is used also in other steps of a container manufacturing line. Note that the specific configuration of the container holder90may be any configuration as long as the configuration is capable of holding the container C.

Next, hereinbelow, a description will be given of one example of a coating method of the coating agent L that uses the coating device10in the present embodiment.

First, after the container C serving as a coating target is moved to a position below the spray gun20, the spray gun20is moved downward, and the shaft21is inserted into the container

Next, after the spray gun20is stopped at the set position, the spray gun20is rotated 180° at any rotation speed and, at the same time, the coating agent L is ejected from the spray nozzle22.

Next, after the spray gun20is moved upward and stopped at the next set position, the spray gun20is rotated 180° at any rotation speed and, at the same time, the coating agent L is ejected from the spray nozzle22.

Thereafter, the entire inner wall surface of the container C is coated with the coating agent L by repeating the rise and the stop of the spray gun20, and the rotation of the spray gun20and the ejection of the coating agent L while changing the rotation speed of the spray gun20at each set position in accordance with the shape and the size of the container C.

Note that the above-described embodiment is one example of the operation of the coating device10of the present invention, and the coating device.10is installed in the up-and-down direction. However, the coating device10only needs to be installed in the gun longitudinal direction, such as the case where the coating device10is installed in the horizontal direction, and the installation mode of the coating device10may be any installation mode.

In addition, the number of movements (the number of rises/the number of stops) of the spray gun20, the rotation speed of the spray gun20at each set position, the ejection amount of the coating agent L, and the speed of each of the descent and the rise of the spray gun20may be determined arbitrarily in accordance with the shape and the size of the container C.

In addition, in the above description, the description has been made on the assumption that the rotation speed of the spray gun20is changed from one set position to another by the rotation control section (the stepping motor61). However, the rotation angle range of the spray gun20may be changed front one set position to another by the rotation control section, such as the case where the spray gun20is rotated 180° at one set position and is rotated 360° at another set position. Further, both of the rotation speed and the rotation angle range of the spray gun20may be changed from one set position to another by the rotation control section.

Furthermore, in the above description, the description has been made on the assumption that the spray gun20is rotated at a constant speed at one set position, but the rotation speed of the spray gun20may be changed during the rotation of the spray gun.20at one set position.

In addition, in the above description, the description has been made on the assumption that the coating agent L is ejected while the spray gun20is rotated in the state in which the spray gun20is stopped at each set position, but the spray gun20may be rotated and the coating agent L may be ejected while the spray gun20is moved, in the gun longitudinal direction without being stopped.

Further, in the above-described embodiment, the configuration is adopted in which the spray gun20is rotated about the axis along the gun longitudinal direction and the container holder90is not rotated. However, a configuration may be adopted in which the spray gun20is not rotated and the container holder90is rotated and, further, a configuration may also be adopted in which both of the spray gun20and the container holder90are rotated. In the case where the configuration is adopted in which the container holder90is rotated, the container holder90may be appropriately driven rotationally by a mechanism similar to the above-described rotary driver60.

In addition, in the above-described embodiment, the configuration is adopted in which the spray gun20is moved in the gun longitudinal direction and the container holder90is not moved. However, a configuration may be adopted in which the spray gun20is not moved and the container holder90is moved and, farther, a configuration may also be adopted in which both of the spray gun20and the container holder90are moved. In the case where the configuration is adopted in which the container holder90is moved, the container holder90may be appropriately moved by a mechanism similar to the above-described mover70.

Further, the description has been made on the assumption that the coating agent L applied to the container C improves the slidability of contents, and the container C is the container which is filled with viscous contents such as a mayonnaise-like food and in which the viscous contents are sealed, but the specific type of the coating agent L and the use of the container C may be any type and any use.

Next, the coating device10according to Embodiment 2of the present invention will be described based onFIG. 4. Herein, the configuration of Embodiment 2 is exactly the same as that of Embodiment 1 described above except part of the configuration, and hence the description of the configuration other than differences will be omitted.

In the above-described coating device10, there is a possibility that, when the inside of the container C is coated with the coating agent L, the coating agent L ejected from the spray nozzle22is atomized in the container C, and the atomized coating agent L adheres to the upper end edge of a container mouth C1and bonding of a seal member to the upper end edge of the container mouth C1is thereby adversely affected, or the atomized coating agent L adheres to the spray nozzle22and the ejection of the coating agent L from the spray nozzle22is thereby adversely affected. In addition, external environment contamination is caused by curling up of the coating agent L atomized in the container C and, further, deformation of the: container C occurs due to an increase in internal pressure, and it becomes difficult to strike a balance between the coating speed of the coating agent L to the inner wall surface of the container C and uniform coating. To cope with this, in the coating device10in Embodiment 2, in order to prevent the occurrence of the above-described situations, an aspirator100capable of facing the longitudinal direction of the container mouth C1(an upper side in an example shown in the drawing) is provided. Note that, although not shown in the drawing, a suction duct or the like is provided on or in the vicinity of the aspirator100as a countermeasure against the external environment contamination.

The aspirator100is formed into a substantially cylindrical shape, includes, as shown inFIG. 4, a gas supply section102that is connected to an air supply source (not shown) with a gas supply pipe105and an air flow amplification flow path section101that has a lower intake port103and an upper ejection port104, and has the function of an amplification mechanism described in Japanese Patent Application Publication No. H04-184000 or Japanese Patent Application Publication No. 2006-291941.

Specifically, the aspirator100is disposed such that the shaft21of the spray gun20is positioned in the air flow amplification flow path section101in the gun longitudinal direction, or the up-and-down:direction in an example-shown in the drawing, and ejects gas such as air supplied to the gas supply section102toward the ejection port104along the inner periphery of the air flow amplification flow path section101at high speed. The aspirator100is configured to suck gas including the coating agent L atomized in the container C from the intake port103disposed to face the upper side of the container mouth C1by the ejection of the gas, and eject the high-speed and high-pressure gas from the ejection port104.

In addition, the aspirator100is configured to be movable along the up-and-down direction independently of the movement of the spray gun20along the gun longitudinal direction, or the up-and-down direction in the example shown in the drawing. Note that the aspirator100may also be disposed in a fixed manner such that the aspirator100is not movable in the up-and-down direction.

Next, hereinbelow, a description will be given of an example of the operation of the coating device10in Embodiment 2. Note that the coating method of the coating agent L that uses the spray gun20and the like is similar to that in Embodiment 1, and hence the detailed description thereof will be omitted.

First, after the container C serving as the coating target, is moved to the position below the spray gun20, the shaft21of the spray gun20is inserted into the container C and, at the same time, the aspirator100is moved downward and is stopped at a position where the intake port103of the air flow amplification flow path section101maintains a slight distance between the intake port103and the container mouth C1.

Note that the distance between the intake port103and the container mouth C1is preferably as short as possible in a range that does not allow the container C itself to deform or adhere to the intake port103due to negative pressure resulting from the suction of the gas in the container C by the aspirator100.

Next, the coating agent L is ejected from the spray nozzle22while the aspirator100sucks the gas in the container C by supplying gas such as air to the gas supply section102, and the inner wall surface of the container C is coated with the coating agent L.

Note that the above-described operation in the embodiment is one example of the operation of the coating device10of the present invention, and the timing of the movement of the aspirator100to the position in the vicinity of the container mouth C and the timing of the suction of the gas in the container C may be determined arbitrarily.

Next, a modification of the aspirator100will be described based onFIG. 5.

The description has been made on the assumption that the above-described aspirator100shown inFIG. 4sucks the coating agent L atomized in the container C during the ejection of the coating agent L from the spray nozzle22.

In contrast to this, the aspirator100of the modification shown inFIG. 5sucks the coating agent L atomized in the container C after the inner wall surface of the container C is coated with the coating agent L by the coating device10in another step in the device of the coating device10or after being installed downstream of the coating device10in the container manufacturing line.

In addition, the aspirator100shown inFIG. 5includes an air ejection nozzle106that is provided such that the air ejection nozzle106is movable along the up-and-down direction, and is inserted into the container C in a state in which the aspirator100is disposed to face the upper side of the container mouth C1, and air A is ejected from the air ejection nozzle106when the coating agent L is sucked by the aspirator100.

Further, a gas suction pipe107is connected to the aspirator100shown inFIG. 5, and the aspirator100sucks gas including the coating agent L atomized in the container C by sucking gas in the container C and the aspirator100from the gas suction pipe107.

Note that the specific configuration of the suction mechanism may also be a configuration that uses a principle other than the principle described above as long as the configuration is capable of sucking the gas from the container mouth C1.