JPH0468989B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a coating device, and more particularly to a coating device for coating a cylindrical member whose both ends are open. (Background of the Invention) Coating by dipping has been widely practiced in the past, and dipping is also a useful method for forming a uniform coating film on the surface of a cylinder-shaped member (hereinafter simply referred to as a cylinder). The method basically involves immersing a cylinder in a coating solution and then pulling the cylinder out of the coating solution at an appropriate speed to coat its surface. In this method, a desired uniform coating film can be obtained by appropriately setting the viscosity, solid content, pulling speed, etc. of the coating solution. By the way, when coating a cylinder by such a dipping method, it may be necessary to prevent the coating liquid from adhering to the inside of the cylinder. Such methods include a method of sealing the lower end of the cylinder and a method of sealing the upper end. In the former case, a method of sealing the lower end of the cylinder and applying it using some kind of auxiliary jig such as a bottom lid. is prone to coating film defects due to air bubbles caused by auxiliary jigs, uneven thickness due to differences in level with the cylinder, peeling and dust generation due to attachment and detachment, and it is necessary to prepare auxiliary jigs for the number of coats to be coated, making it difficult to reuse them. However, there are also problems in terms of productivity, such as the need to wash and remove the paint film on the auxiliary jig. On the other hand, in the case of a method in which the upper end of the cylinder is sealed and coated, the above-mentioned drawbacks are not a problem in most respects. However, even in such an advantageous top-closed coating method, the following points must be taken into consideration. In other words, the air inside the cylinder expands due to a slight temperature difference between the coating solution and the outside air temperature, or the solvent of the coating solution evaporates inside the cylinder and the volume increases, causing air bubbles to form from the bottom end of the cylinder during dip coating. The problem is that it is pushed out into the liquid and floats to the surface of the coating liquid, causing the liquid level to fluctuate greatly, often resulting in uneven coating. (Objective of the Invention) The present invention eliminates the above-mentioned problems, and when coating the outer peripheral surface of the cylinder, prevents excessive penetration of the coating liquid into the inside of the cylinder, and prevents leakage of air bubbles from the lower end to ensure uniform coating. The object of the present invention is to provide a good coating device that can form a coating film. (Summary of the Invention) The gist of the present invention, which has been made to achieve the above object, is to attach a hanging tool to one end of a cylindrical member whose both ends are open. In a coating apparatus that applies coating by suspending the cylinder-shaped member with the end facing upward, immersing the cylinder-shaped member in a coating liquid from the lower end, and then pulling it up, the hanging tool includes a cylinder-shaped member. The air chamber, which is located in the inner cavity of the member and faces the free surface of the coating liquid, is separated from the outside air, and when the pressure inside the air chamber increases, the volume inside the air chamber is increased to separate the pressure from the outside air. The coating device is characterized in that the hanging device has a pressure balancing device. For example, as shown in FIG. 1, the pressure balance device is formed as an expandable air tank that is accommodated in the internal space of the cylinder by attaching a hanging tool to the cylinder. It is sufficient to communicate with the outside air as an outside air chamber. With this configuration, due to the increase in pressure in the closed air chamber that occurs when the cylinder is immersed in the coating liquid,
The air tank deflates by exhausting the internal air, allowing a portion of the coating liquid to enter the cylinder and preventing air bubbles from being released into the coating liquid from the lower end of the cylinder during dip coating. In addition to the above, as shown in Figure 2,
An air tank external to the cylinder communicating with the cylinder interior may be provided, and this external air tank may be expanded in response to an increase in pressure in the cylinder interior. In addition, when the cylinder during dip coating is immersed in the coating solution to the deepest level, the air tank is locked to prevent it from returning to its deformed state, and the cylinder is pulled up from the coating solution while maintaining this locked state. By releasing the lock and returning to the original state at the time of replacement, the release of the bubbles can be more reliably prevented. In addition, in the former type where a pressure balance device using a diaphragm is provided in the inner space of the cylinder, the two air chambers separated by the diaphragm are strictly speaking upper and lower air chambers.
It is not necessary to have a lower positional relationship, and there is no particular need for the upper air chamber to be located in the inner space of the cylinder. In short, the free surface of the coating liquid formed on the lower side of the inner cavity of the cylinder faces a sealed air chamber that is cut off from the outside air, and the pressure increase in this sealed air chamber is balanced in relation to the outside air chamber. That's fine. (Example of the Invention) An example of the present invention will be described below based on the drawings while contrasting with a comparative example. Figure 3 shows the cylinder 6 with both ends open.
This figure shows the side surface of the cylinder after it has been immersed in the coating liquid 7 after its upper end has been sealed with a cylinder suspender 4 that also serves as an open end blocker. indicates a case in which there is no way to escape outside except by leaking from the bottom end. Note that 5 is an O-ring. Figure 3A shows how the air inside the sealed cylinder expands in volume due to the temperature difference between the coating liquid 7 and the outside air temperature and the evaporation of the solvent in the coating liquid.
FIG. 3B shows how the bubbles are released into the coating liquid 7 . In such a state, a uniform coating film cannot be formed. FIG. 1 illustrates the state of coating using the coating apparatus of the present invention, in which a cylinder 6 with both ends open is suspended by a hanging tool 4 so as to be movable up and down. Inside the hanging tool 4, there is an air tank 1 as an elastic and expandable pressure balance device.
is assembled so as to divide the inner space of the cylinder into an outside air chamber 8 and a closed air chamber 9, and is further provided with a hook rod 2 for locking the air tank 1 when it contracts to a predetermined length. and a stopper 3 are provided. FIG. 1A shows a side view of the initial state in which the hanging tool 4 is attached to the cylinder 6, and in this figure, the locks 2 and 3 are released. Figure 1B
shows a side view of the state when the cylinder 6 has begun to be immersed in the coating liquid 7 , and shows a state in which the air tank 1 has slightly contracted as the internal pressure of the cylinder 6 increases. FIG. 1C shows a side view of the state when the cylinder 6 is immersed in the coating liquid 7 to the deepest extent, at which time the air tank 1 is in the most contracted state and the hook rod 2 is engaged with the stopper 3. Return extension is locked. FIG. 1D shows a side view of the cylinder 6 being lifted out of the coating solution 7 and during coating, with the air tank 1 remaining locked in a contracted state. By locking the air tank in this way, a part of the coating liquid 7 enters the inner space from the lower end of the cylinder 6, and the volume inside the cylinder increases due to the temperature difference between the coating liquid and the outside air temperature and the evaporation of the solvent in the coating liquid. Even if the cylinder 6 increases as shown in Figure 3B,
No air bubbles are released into the coating liquid from the lower end of the tube. After the coating is completed, the lock on the air tank 1 is released (automatically or manually), a new cylinder is installed, and the coating can be recoated in the order of A, B, C, and D in FIG. 1. In this example, since the diaphragm accommodated in the inner space of the cylinder is configured as an air tank, it can be manufactured extremely easily and at low cost.Moreover, the contraction of the air tank is locked even while the cylinder is being raised, so that This has the advantage that bubble release can be more reliably prevented and a coating film of a desired thickness can be uniformly applied onto the cylinder without using a complicated air bleed device. FIG. 2 illustrates the state of coating using a coating apparatus according to another embodiment of the present invention, in which a cylinder 6 with both ends open is suspended by a hanging tool 4 so as to be movable up and down. On the outside of this hanging tool 4, there is an elastic, expandable air tank 1, a hook bar 2 and a stop for locking the air tank 1 from returning and contracting when it is extended to a predetermined length. Ingredients 3
is provided. FIG. 2A shows a side view of the initial state in which the cylinder 6 is attached to the hanger 4, and in this figure, the locks 2 and 3 are released.
FIG. 2B shows a side view of the cylinder 6 when it begins to be immersed in the coating liquid 7 , and shows the air tank 1 slightly expanded as the internal pressure of the cylinder 6 increases. FIG. 2C shows a side view of the cylinder 6 when it is immersed in the coating liquid at its deepest point, at which time the air tank 1 is at its most extended position and the hook bar 2 is engaged with the stopper 3. Deflation of the air tank 1 is locked. FIG. 2D shows a side view of the state in which the cylinder 6 is pulled up from the coating liquid 7 and coating is in progress, with the expansion of the air tank 1 remaining locked. By locking the air tank after extending it in this way, a part of the coating liquid 7 enters the inner space from the lower end of the cylinder 6, and due to the difference in temperature between the coating liquid and the outside air temperature and the evaporation of the solvent in the coating liquid, the coating liquid 7 enters the cylinder 6. Even if the volume inside increases, air bubbles will not be released into the coating liquid from the lower end of the cylinder 6 as shown in FIG. 3B.
After the coating is completed, the lock on the air tank 1 is released (automatically or manually), a new cylinder is attached, and the coating can be recoated in the order of A, B, C, and D in FIG. 1. Also in this embodiment, as in the example shown in FIG. 1, prevention of bubble leakage, simplification of structure,
There are advantages such as (Effects of the Invention) As described above, according to the coating device of the present invention, coating is uniformly and well performed on the outer circumferential surface of a cylindrical member with open ends, and has practical benefits. is extremely large.

[Brief explanation of the drawing]

Figures 1A, B, C, and D illustrate a coating device according to an embodiment of the present invention; Figure 1A is a side view of the coating device with a cylinder attached; Figures B, C, and D 2 are side views sequentially showing the states of the process of dipping the cylinder in the coating solution, and FIGS. 2A, B, C, and D are views similar to FIG. 1 showing other embodiments. Figures 3A and 3B illustrate the coating device of the comparative example. Figure A is a side view of the cylinder mounted on a hanging tool and immersed in the coating liquid, and Figure B is a side view of the cylinder with air bubbles released from the bottom end of the cylinder. FIG. 1: Air tank, 2: Hanging rod, 3: Stopper, 4: Cylinder hanging tool, 5: O-ring,
6: Cylinder, 7 : Application liquid, 8: Outside air chamber, 9:
Closed air chamber.

Claims (1)

[Claims] 1 Attach a hanging tool to one end of a cylinder-shaped member with both ends open, suspend it with that end facing upward, and apply from the lower end of the cylinder-shaped member. In a coating device that coats by immersing it in a liquid and then pulling it up, the hanging tool is arranged so as to separate an air chamber from the outside air, which is located in the inner cavity of a cylinder-shaped member and faces the free surface of the coating liquid; The coating device further includes a pressure balance device that balances the pressure with outside air by increasing the volume inside the air chamber when the pressure inside the air chamber increases.