JPH0651148B2 - Immersion coating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a dip coating apparatus that coats only on the outer surface of a cylindrical body.

[Conventional technology]

Conventionally, various methods of applying a coating material to the surface of a cylindrical body are known, but a dip coating method is adopted particularly when importance is attached to the smoothness of the coating film.

In a general dipping method, the cylindrical body is dipped in the coating material and then pulled up at an appropriate speed to perform coating. However, in the case of a cylindrical body that is open in both the upper and lower directions, the paint also penetrates into the inside of the cylinder, so that the inner surface is also coated. Therefore, not only is the paint wasted, but it also becomes difficult to dry the inner surface of the cylindrical body, or the problem of contamination occurs.

In order to solve this problem, there is also a method of attaching a lid to the bottom of the cylinder to prevent the paint from adhering to the inner surface of the cylinder. However, this method has a low workability because it takes time to attach the lid. Further, since the paint adheres to the surface of the lid during the dipping, it is necessary to wash the lid, which makes maintenance work troublesome.

On the contrary, by closing the upper part of the tubular body, when the tubular body is immersed in the paint, air is trapped inside the tubular body,
There is also a method of preventing the paint from entering by the air pressure inside the cylinder. When a cylinder whose top is closed in this way is immersed in paint and pulled up, the pressure of the air trapped inside the cylinder rises as the solvent of the paint evaporates, and the volume of the cylinder was confined to the original. When the volume is larger than the volume, bubbles are generated from the lower part of the cylinder. The bubbles burst on the surface of the paint and disturb the liquid surface of the paint to cause a serious coating film defect. Therefore, it is necessary to prevent the generation of the foam.

[Problems to be solved by the invention]

As a method for preventing the generation of bubbles, Japanese Patent Laid-Open No. 58-186472
The publication describes that the generation of bubbles is prevented by operating an electromagnetic valve according to the internal pressure to maintain the internal pressure at a required value.

However, this coating method requires a mechanism for detecting the internal pressure. Further, an accessory device such as a pressure sensor, a solenoid valve, and an electric circuit for controlling these is required.

Further, for a tubular body having an open upper portion, it is necessary to close the upper portion with a closing device, and it is possible to prevent the generation of bubbles by attaching a pressure adjusting mechanism to the closing device. Akira
59-4467 and JP-A-60-132678. In this system, a valve is provided in the upper closing device as a pressure adjusting mechanism, and the liquid level of the paint that has entered the cylinder when the cylinder is pulled up adjusts the air pressure of the cylinder to prevent the generation of bubbles. However, it is difficult to adjust the timing of opening the valve when the cylinder is pulled up.

Further, Japanese Patent Application Laid-Open No. 60-255164 also describes a method of preventing the generation of bubbles by a pressure balance device that changes the volume by changing the pressure inside the cylindrical body. However, in this method, the pressure balance device uses a pressure inside the cylinder as a working source to operate a mechanical device,
There are mechanical difficulties.

As described above, the dip coating method for a cylindrical body has a problem that it is not easy to reliably suppress the generation of bubbles that occur when the cylindrical body is pulled out from the paint tank.

Therefore, the present invention, by absorbing the pressure rise in the cylinder due to the evaporation of the solvent, reliably prevents the occurrence of bubbles with a simple structure without the need for complicated operations, good coating state The aim is to be always available.

[Means and Actions for Solving Problems]

The dip coating device of the present invention is a support member that hermetically supports the upper end of a coating target cylinder whose upper and lower ends are open, and immerses the cylinder in the coating material to expand the cylinder. And a variable volume that contracts and deforms.

In the present invention, the variable volume body is contracted during the immersion of the cylinder to reduce the volume of the enclosed gas in the cylinder. For this reason, the coating liquid level in the cylinder rises above the lower end of the cylinder. As a result, even if the pressure of the enclosed gas rises due to the vapor pressure of the paint in the cylinder, or if the enclosed gas expands when the cylinder is pulled up and the paint liquid level in the cylinder drops, it will reach the lower end of the cylinder. Try not to reach. Therefore, the sealed gas does not leak to the outside as bubbles.

〔Example〕

Hereinafter, the present invention will be specifically described based on the embodiments shown in the drawings.

FIG. 1 is a vertical cross-sectional view schematically showing the coating apparatus of the present invention together with a cylinder to be coated.

In the figure, the cylindrical body 1 to be applied is a pipe such as aluminum whose upper and lower ends are open, and the necessary coating material is applied only to the outer peripheral surface thereof. In the coating apparatus A used for coating the cylindrical body 1, a flange portion 3 for covering the upper end of the cylindrical body 1 is integrally attached to the lower end of a hollow support member 2.
An elevating member 4 for elevating the supporting member 2 coaxially with the cylinder 1 is provided. The support member 2 is provided with a pull-up rod 5 that can be moved up and down through the inside thereof, and the base end of the pull-up member 6 is pivotally attached to the lower end of the pull-up rod 5.

The elevating member 4 can be moved up and down in conjunction with a fluid pressure cylinder and other mechanisms to change the position of the support member 2 with respect to the tubular body 1. Flange portion 3 provided at the lower end of the support member 2
In order to seal the upper end of the cylinder 1, the lower surface has a stepped shape, and the sealing material 7 that is in close contact with the upper end surface of the cylinder 1 is attached.
Further, the pulling rod 5 has a driving device 8 using an air cylinder, a solenoid coil, a motor, or the like provided in the elevating member 4 in order to insert and pull up the supporting member 2 in the axial direction of the supporting member 2.

Further, the lifting member 6 pivotally attached to the lower end of the lifting rod 5
Is urged in the direction in which it is folded toward the center of the pull-up rod 5 in the figure, and its base end is pivotally attached to the pull-up rod 5. A coil spring 9 is arranged between the pull-up member 6 and the flange portion 3, and an engaging body 10 for pressing the pull-up member 6 downward is provided at the lower end of the coil spring 9 in the vertical direction with respect to the pull-up rod 5. It is slidably attached to. The pulling member 6 operates so that the tip is opened after being inserted into the tubular body 1, and by pressing the tip against the inner peripheral surface of the tubular body 1, the tubular body 1 can be supported and conveyed up and down. It is what An elastic body such as rubber that exerts a large frictional force may be attached to the tip of the pulling member 6 that abuts on the inner peripheral surface of the tubular body 1 in order to stably support the tubular body 1.

In the coating apparatus A described above, if the flange portion 3 of the support member 2 is set on the upper end of the tubular body 1, it is possible to immerse the tubular body 1 in a paint tank 14 described later in a sealed state. In addition to this structure, in order to prevent the generation of bubbles due to evaporation of the paint solvent and the like, a variable volume body 11 that absorbs a pressure increase in the cylindrical body 1 is arranged on the lower surface side of the flange portion 3. The variable volume body 11 is, for example, a balloon made of an elastic material such as rubber and is connected to an external compressed air supply source (not shown) by a hose 12. Then, by supplying air, the volume can be freely changed to change the volume occupied in the cylindrical body 1. A solenoid valve 13 is provided in the middle of the hose 12 so that the variable volume body can be connected by connecting to a compressed air supply source or switching to a flow path open to the atmosphere.
11 expansion and contraction operations are possible.

FIG. 2 shows the cylindrical body 1 held by the support member 2 in the paint tank 14
It is a schematic sectional drawing which shows the time of starting insertion in.

The paint tank 14 has a structure in which a supply port 15 for the paint B is provided at the lower end and a gutter 16 for collecting the overflowed paint B is provided at the upper end.
It is a circulation type in which the paint is supplied again from 15 to the paint tank 14.

To insert the cylinder 1 into the paint tank 14, the pulling member 6 is inserted into the cylinder 1 in the state shown in FIG.
Start by holding. Then, the pull-up rod 5 is raised by the drive device 8, and the pull-up member 6 is pressed down by the engaging body 10 to open the pull-up member 6. By the operation of the pulling member 6, the cylindrical body 1 is supported with the inner peripheral surface thereof being restrained by the tip of the pulling member 6, and at the same time, the sealing material 7 of the flange portion 3 is brought into close contact with the upper end surface of the cylindrical body 1. To seal the inside of the cylinder 1. Next, the elevating member 4 is lowered, and as shown in FIG.
Insert within 14. At the time of starting the insertion, the variable volume body 11 is in an expanded state.

After inserting the tubular body 1 into the paint B in the paint tank 14 in the above manner, the elevating member 4 is further lowered in a state where the interior of the variable volume body 11 is opened to the atmosphere by the solenoid valve 13 as shown in FIG. .
By this operation, the inner pressure of the cylinder 1 rises as the cylinder 1 is submerged in the paint B, so that the air in the variable volume body 11 is discharged to the outside. Therefore, the liquid level 17 of the paint B rises by an amount substantially equal to the volume occupied by the variable volume body 11 at the initial stage of insertion, and the pressure balance inside and outside the cylinder body 1 is maintained.

Further, as shown in FIG. 4, when the elevating member 4 is moved down to move the entire cylindrical body 1 into the coating material B, the process of immersing the surface of the cylindrical body 1 is completed. It should be noted that the process of discharging air from the variable volume body 11 may be from the time when the cylindrical body 1 is inserted into the paint B to the completion of FIG.
Prior to the process of pulling up, the liquid level 17 may be raised to enter the lower part of the cylinder 1.

Next, the process of pulling up the cylinder body 1 after immersion from the paint tank 14 is performed by raising the elevating member 4 while holding the cylinder body 1 by the support member 2. In this pulling up, the solvent of the paint B evaporates and the inner circumference of the cylinder 1 and the liquid surface 17
The pressure in the cylinder body 1 partitioned by the pressure rises, and as a result, the volume of gas occupied in the cylinder body 1 tends to increase. On the other hand, since the volume occupied by the variable volume body 11 is eliminated in the insertion process to reduce the volume of the enclosed air in advance, the pressure increase due to the evaporation of the solvent of the paint B can be absorbed. That is, even if the pressure in the cylinder 1 rises, the liquid level 17 is still in the lower part of the cylinder 1, and therefore when the cylinder 1 is pulled up, the pressure of the pressure containing the evaporating solvent is increased from the inside of the cylinder 1. High gas will not leak out. Therefore, in the process of pulling up the tubular body 1, bubbles are not generated due to the evaporation of the solvent, and good coating conditions can be obtained.

Incidentally, since such bubble generation is prevented by utilizing the volume change of the variable volume body 11, the volume change amount is set so that the sealed gas does not leak from the cylinder body 1 to the outside. That is of course. This setting condition has a factor such as the evaporation pressure of the solvent of the paint B to be used. However, if the amount of change is too large, the height of the paint B that enters the inside of the cylinder 1 becomes large, so the paint B is wasted. It is not preferable from the point of view.

The cylindrical body 1 that has been applied and pulled up from the paint tank 14 as described above is conveyed to a predetermined position by an operation of rotating the elevating member 4 or the like, and is lowered to the supporting member 2 by lowering the pulling rod 5. The restraint is released.

FIG. 5 is a schematic cross-sectional view showing another embodiment, in which the attachment / detachment of the cylinder 1 to / from the support member 2 is replaced by a mechanical means such as the pulling member 6 shown in the above-mentioned embodiment. This is a structure that utilizes the pressure of.

In the figure, on the peripheral surface of the flange portion 3 provided at the lower end of the support member 2 which is moved up and down by an elevating member (not shown), the cylindrical body 1
A hollow diaphragm 20 is arranged so as to be in close contact with the inner peripheral surface of the. Further, a variable volume body 21 for changing the volume of the enclosed gas in the cylindrical body 1 is attached to the lower surface of the flange portion 3. The variable volume body 21 can be expanded and contracted by using an elastic material such as rubber, and fulfills the same function as in the above-mentioned embodiment. Also, these diaphragm 20 and variable volume
Supply and discharge pipes 22 and 23 for supplying and discharging the working fluid are connected to 21, respectively. As the working fluid, various kinds such as air and water can be adopted, and a valve for supplying and discharging the working fluid is provided in the piping system. When compressed air is used as the working fluid as in the above-described embodiment, a simple structure can be obtained by using an air open type solenoid valve.

In the coating work of the cylindrical body 1 by the above coating apparatus A,
First, after inserting the flange portion 3 of the support member 2 from the upper end of the cylindrical body 1, when a working fluid is supplied to the diaphragm 20, the diaphragm 20 expands and adheres to the inner peripheral surface of the cylindrical body 1 as shown in the drawing. Then, if the pressure of the working fluid is increased, the cylindrical body 1 can be firmly held against the flange portion 3, and in this state, it is lowered into the paint tank. After that, the working fluid was discharged from the previously expanded variable capacity body 21 in the same manner as in the above-described embodiment, and the coating material B was operated so as to enter the lower portion of the cylindrical body 1 to complete the coating. At this time, the cylinder 1 is pulled out from the paint tank.

In this way, the support member 2 and the tubular body 1 can be integrated by the diaphragm 20 for supplying and discharging the working fluid, and the pressure increase in the tubular body 1 due to the evaporation of the solvent can be performed by the variable volume body 21 provided in the flange portion 3. Can be absorbed. Therefore, the cylindrical body 1 can be held and the generation of bubbles in the paint tank can be prevented without requiring a complicated mechanical element or the like. The sealing member 7 is not required for the flange portion 3 as long as the sealing performance between the flange portion 3 and the inner surface of the cylindrical body 1 by the diaphragm 20 can be maintained high.

The present invention can be applied to all shapes of cylinders, and is particularly effective when coating treatment is applied to an electrophotographic photoreceptor, since unevenness and defects of the coating material do not occur. That is, in a photoconductor drum used for electrophotographic copying or the like, nonuniformity of the thickness of the photoconductor layer causes disorder of a copied image, so that it is an important subject to eliminate unevenness and defects of the coating film.

〔The invention's effect〕

As described above, in the present invention, after sealing the upper end of the tubular body and immersing the tubular body in the coating material, the fluid in the variable volume body is discharged to the outside to remove the enclosed gas in the tubular body. The coating liquid level in the cylinder is made higher than the lower end of the cylinder. Therefore, even if the solvent of the paint evaporates during application and the pressure of the enclosed gas in the cylinder rises, or if the enclosed gas expands when the cylinder is pulled up,
Since the volume of the enclosed gas is reduced in advance by the amount capable of absorbing these, the enclosed gas does not leak to the outside. As a result, in the process of pulling up the tubular body from the coating material after the immersion, it is possible to reliably prevent the generation of bubbles due to the enclosed gas, and it is possible to perform good coating without unevenness or defects.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the coating device of the present invention together with a cylinder, FIGS. 2 to 4 are schematic cross-sectional views showing a coating method on the cylinder, and FIG. 5 is another embodiment of the coating device. It is a schematic sectional drawing of the principal part shown. DESCRIPTION OF SYMBOLS 1 ... Cylindrical body, 2 ... Support member 3 ... Flange part, 4 ... Elevating member 5 ... Lifting rod, 6 ... Lifting member 7 ... Seal material, 8 ... Drive device 9 ... Coil spring, 10 ... Engaging body 11 ... Variable volume body , 12 ... Hose 13 ... Solenoid valve, 14 ... Paint tank 15 ... Supply port, 16 ... Gutter 17 ... Liquid level, 20 ... Diaphragm 21 ... Variable volume, 22,23 ... Supply / discharge pipe A ... Coating device, B ... Paint

Claims (1)

[Claims] 1. A support member for sealing and supporting the upper end of a coating-use cylinder whose upper and lower ends are open and for immersing the cylinder in a coating material to expand and contract inside the cylinder. An immersion coating apparatus, which is provided with a deformable variable volume body.