JPH0753256B2 - Coating equipment for cylindrical bodies such as engine pistons - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a coating apparatus suitable for coating the outer peripheral surface of a cylindrical body such as an engine piston having a hole or a convex portion on the outer peripheral surface.

[Conventional technology]

FIG. 21 shows an example of an engine piston,
In the case of this piston, there is an effect that it is possible to smooth the sliding contact with the inner wall surface of the cylinder by forming a coating film for solid lubrication on the outer peripheral surface of the skirt portion. As a result,
The initial acclimatization time of the engine is greatly reduced to less than about 1/2, and vibration and noise during operation can be reduced and fuel economy can be improved. Conventionally, a spray method as shown in FIG. 22 has been used for coating such engine pistons. As shown in the figure, the crown part is fitted to the support and the piston pin hole is sealed by the masking plug.The piston is sprayed with a spray gun or the like while rotating to form a coating film only on the skirt part. It was supposed to be. Further, a convex surface portion to be coated is formed on this skirt portion as a sliding contact surface, and FIGS. 23 (A), (B) and (C) show a typical example of the pattern of the convex surface portion. However, since it suffices that the coating film be formed only on such a convex surface portion of the skirt portion, an area other than the convex surface portion (hereinafter, referred to as a concave surface portion) is appropriately smoked when spraying with a spray gun. Is given.

[Problems to be Solved by the Invention]

In such a conventional spray coating method, most of the paint sprayed from the spray gun adheres to a support tool other than the convex surface, a masking plug, etc., and is scattered in the air, resulting in a significant waste of the paint. For this reason, the coating rate of the paint is extremely low at about 20%, and the paint that adheres to the support, etc. is applied to the surface of the support, etc. by being subjected to a calcination process along with the piston after coating in the subsequent process. As the paint gradually accumulated, the paint that had accumulated in this way was frequently peeled off and forced to perform a troublesome work. Further, the masking work on the concave portion also requires time and labor, and therefore the productivity is inevitably lowered. Further, since it is a spray type, there is a problem such as contamination of the working environment due to fine particles of the coating material scattered.

In view of such circumstances, it is an object of the present invention to provide a coating device capable of efficiently and accurately coating a cylindrical body to be coated of this kind by eliminating the waste of the coating material.

[Means and Actions for Solving the Problems]

The coating apparatus according to the present invention is capable of rotating around a horizontal axis and being vertically movably mounted, and at a position close to the lower side thereof, rotatable about an axis parallel to the cylinder to be coated. A mounted cylindrical roll, a paint container capable of storing paint so that a part of the peripheral surface on the lower side of the cylindrical roll is immersed, and a coated cylindrical body descends to come into contact with the cylindrical roll. And a damper device that applies a braking force to the coated cylindrical body.

Therefore, it is possible to apply the braking force by the damper device during the descending operation for the coated cylinder to come into contact with the cylindrical roll, and rotate independently while the coated cylinder and the cylindrical roll are in contact with each other. It is possible to apply the paint in the paint container to the surface of the cylinder to be coated by
The operation of the device can be made smooth and the coating film can be made uniform.

Further, the coating device is a scraper for peeling off the paint remaining on the cylindrical roll in the paint container, a viscosity adjusting device for the paint in the paint container, or a paint container and a paint container connected between the viscosity adjusting devices. An overflow pipe that keeps the liquid surface of the paint constant, and a supporting roller that holds the cylindrical body to be coated in a contact position with the cylindrical roll may be provided, which can further improve coating film characteristics such as film thickness. .

〔Example〕

An embodiment of a coating device for a cylindrical body according to the present invention will be described below with reference to the drawings. It should be noted that this embodiment is an example of the engine piston shown in FIG. 21 in the explanation of the prior art as the coated cylindrical body to be coated.

First, the coating apparatus of the present invention will be described. In FIG. 1, 1 is a base, 2 is a cylinder to be coated, which is an air cylinder or the like vertically attached to a frame 1a standing upright from the base 1. Lifting drive means 3 for the body, 3 is a slide table that can be moved up and down by the lift drive means 2, and 4 and 4'are plummer fixedly mounted on a horizontally mounted substrate 3a at the upper end of the slide table 3. Block 5 is a plummer block
Through hole for vacuum evacuation supported by 4, 4 '
A rotary shaft on which a is formed, 6 is a transmission gear attached to one end of the rotary shaft 5, 7 is a drive motor capable of rotating the rotary shaft 5 via the transmission gear 6, and 8 is another end of the rotary shaft 5. A holder that is attached and can fit the crown portion of the pistol to support the piston coaxially with the rotating shaft 5 as shown in the figure, and 9 is a holder that can be in close contact with the upper end surface of the crown portion of the piston. A vacuum pad mounted inside 8 is provided with 10 so that its axis is parallel to the axis of the piston at a position near the lower side of the piston via a support shaft 10a rotatably supported by the frame bodies 1a and 1a '. The cylindrical roll 11 is mounted on the base, and 11 is a paint container (see FIG. 2) capable of storing the paint so that a part of the peripheral surface of the cylindrical roll 10 is immersed under the cylindrical roll 10. . The piston is brought into contact with the cylindrical roll 10 as described later, and FIG. 3 shows a preferable contact state between the two. That is, the skirt portion of the piston is not a right cylinder but a drum shape curved in the longitudinal direction by about several tens of microns, and is in point contact with the outer peripheral surface of the cylindrical roll 10 in a strict sense. For this reason, when one of the end portions of the skirt portion shown in FIGS. 4 and 5 is contacted in a one-sided contact state, the film thickness of the coating film is not uniform or the paint cannot be transferred. Therefore, the contact point between them is set so as to occur at the center of the skirt as shown in FIG. Further, 12 is a drive motor capable of rotating the cylindrical roll 10 via a universal joint 13 and the like, and 14 is a lower end of the slide table 3 so as to apply a braking force to the piston immediately before the piston comes into contact with the cylindrical roll 10. It is a damper device that is designed to come into contact with.

Next, an example of a coating method for forming a coating film on the piston by the apparatus having the above-mentioned configuration will be described. FIG. 6 shows the basic process, and the piston that has been pretreated such as cleaning first is Preheated. This preheating step can improve the fixability of the coating which is subsequently transferred to the skirt, but the temperature is below 100 ° C, preferably in the range of 80-85 °. Here, a mixture of a solid lubricant composed of molybdenum disulfide and PTFE and a binder such as polyamide-imide is used as the paint, but the paint viscosity for obtaining good coating properties is in the range of 13 to 19 sec FC # 4. is there. The preheated piston is lifted by the lifting drive means 2 via the slide table 3 of the coating apparatus.
It is fixed to the holder 8 by being attached to the holder 8 and being evacuated through the vacuum pad 9. Then, a uniform paint film is formed by the paint in the paint container 11 and the piston is lowered so as to come into contact with the cylindrical roll 10 rotating at a constant speed in a certain direction. Since the damper device 14 comes into contact with the lower end of the slide table 3 to apply a braking force to the descending motion of the piston, the impact due to the collision that occurs when the piston is brought into abrupt contact with the cylindrical roll 10 is Impair the parallelism between the axes of the roll 10, or
It is possible to prevent dents or the like from being formed on the outer peripheral surface. When the slide table 3 reaches the lower end position, a predetermined contact pressure is generated between the piston and the cylindrical roll 10, and the piston starts rotating at a constant speed in the same direction as the rotating direction of the cylindrical roll 10 ( (Fig. 2) This starts the transfer of the piston skirt to the convex surface. The convex portion of the piston and the outer peripheral surface of the cylindrical roll 10 are in line contact with each other, but are selected so that the contact area is minimized as the transfer start point, that is, the position corresponding to the piston pin hole. Is the best.

By the way, regarding the relationship between the peripheral speed of the piston and the peripheral speed of the cylindrical roll 10 and the film thickness of the coating film to be formed, the smaller the peripheral speed in the case of the piston, and the peripheral speed in the case of the cylindrical roll 10. The larger the thickness, the larger the film thickness tends to correspond to each case. Therefore, the peripheral velocity ratio between the two is an important factor affecting the coating film characteristics, particularly the film thickness. The peripheral speed is determined by the diameter and the number of revolutions, but as the diameter of the cylindrical roll 10, the area exposed to the atmosphere from the liquid surface of the paint container 11 is reduced to reduce the cylindrical roll.
In order to prevent the solvent from evaporating from the paint film formed on the outer peripheral surface of 10, it is preferable to make it smaller. Therefore, the peripheral speed ratio mentioned above should be set within a certain optimum range, which corresponds to the specific diameter of the piston to be coated, which is set for each individual piston.

From the transfer start point, the piston makes one rotation while keeping contact with the cylindrical roll 10, so that the paint film of the cylindrical roll 10 is transferred only to the convex portion of the skirt portion to form a single coating film. In this case, if the peripheral velocity, contact pressure, etc. of the piston and the cylindrical roll 10 are set appropriately, the piston coating film formed by transfer has a uniform film thickness and a smooth coating film surface. And shows excellent coating characteristics. After such transfer, the piston is raised by the elevating drive means 2 via the slide table 3 and the like. In this case, since the damper device 14 urges the piston upward, the piston is immediately moved to the cylinder after the transfer is completed. The contact state with the roll 10 can be released. As described above, the contact and separation of the piston and the cylindrical roll 10 can be appropriately and quickly performed by the action of the damper device 14, which is convenient for uniformizing the coating film when performing transfer with rotation. is there. In addition, this damper device 14
Can be configured by using an air damper, a coil spring, or the like.

Thus, the coating (transfer) process is completed, and then the process proceeds to the drying process (see FIG. 6), which is carried out by raising the piston and subsequently rotating the piston by the drive motor 7 for a predetermined time. In this case, it is possible to prevent the coating film having fluidity after transfer from sagging and to fix the coating film evenly on the convex surface of the piston. In this case, the piston is preferably The coating film formed can be further smoothed by heating in an atmosphere of 150 ° C or lower. Further, the time required for the drying step can be significantly shortened by blowing hot air onto the coating surface of the piston, but the temperature of such hot air is preferably 200 ° C. or lower, and the wind speed of the coating depends on the wind pressure. It is suitable to be 3 m / sec or less so that so-called waviness does not occur on the surface. During this time, the cylindrical roll 10 may be continuously rotated by the drive motor 12.

In the baking process, after the rotation of the drive motor 7 and the suction of the vacuum pad 9 are stopped, the dried piston removed from the holder 8 is baked and dried in the baking furnace. The baking conditions at this time are slightly different depending on the characteristics of the paint, but are generally 180 ° C /
It is in the range of 60 minutes to 230 ° C / 30 minutes.

According to the coating method consisting of the above-mentioned basic steps, a uniform and smooth coating film is formed only on the convex portion of the skirt portion of the piston. Almost 100% paint usage without
It becomes possible to make it into%. Further, it is possible to eliminate the contamination of the work environment or the cleaning of the adhered paint due to the scattering of the paint as in the case of the above-mentioned spray method, and the work efficiency is improved.

FIG. 7 shows an outline of a paint supply system for the paint container 11. Here, the amount of paint supplied to the piston for forming a coating film is controlled by adjusting the rotation speed of the cylindrical roll 10, and the amount of paint supplied by such control is kept constant. Are necessary for forming a uniform coating film. This supply amount is substantially proportional to this rotation speed in the low rotation speed region of the cylindrical roll 10, while the film thickness of the coating film to be formed on the outer peripheral surface of the piston depends on the viscosity of the coating material. Further, as shown in FIGS. 8 and 9, the change in the viscosity of the paint is further influenced by the dilution ratio of the paint in the solvent and the temperature. Therefore, in order to keep the film thickness of the coating film constant and to control the supply amount of the paint to the piston only by the rotation speed of the cylindrical roll 10, the cylindrical roll 10 is immersed in the paint container 11. It is necessary that a certain amount of paint with a constant viscosity is always stored.
By the way, in FIG. 7 in the drawing, 15 is a paint tank having a sufficiently large volume with respect to the paint container 11, and 16 is a metering pump for feeding the paint in the paint tank 15 to the paint container 11 via a pipe 17. , 18 is a pipe for returning excess paint in the paint container 11 to the paint tank 15, 19 is a paint tank 15
Automatic viscosity controller, which can detect the viscosity of the paint inside, 20
And 21 are suitable agitators and heat exchangers that can be provided as necessary, 22 is a solvent tank for storing a solvent for paint, and 23 is a solenoid valve whose opening and closing can be controlled by a signal of an automatic viscosity controller 19. , 24 are pipes for feeding the solvent in the solvent tank 22 to the paint tank 15. The paint viscosity adjusting device is constituted by these.

In the coating apparatus of this second embodiment, the automatic viscosity controller
When there is a difference between the desired paint viscosity preset in 19 and the paint viscosity in the paint tank 15, the signal from the automatic viscosity controller 19 causes the paint viscosity in the paint tank 15 to become the desired viscosity. Then, the solenoid valve 23 is opened to supply the solvent to the paint tank 15. In this case, the stirrer 20 equalizes the paint viscosity in the paint tank 15 as a whole, and the heat exchanger
21 allows the paint temperature to be adjusted accordingly. As a method of replenishing such a solvent, the solvent tank 22 is installed at a position higher than the paint tank 15 and the pipe is opened and closed by opening and closing the solenoid valve 23.
In addition to dropping the solvent into the paint tank 15 via 24,
A metering pump or the like may be arranged in the middle of the pipe 24, and the operation of this pump may be controlled by a signal from the automatic viscosity controller 19. The paint in the paint tank 15 having a desired viscosity is supplied to the paint container 11 via the pipe 17 by the metering pump 16.
Excess paint in the paint container 11
It is returned to the paint tank 15 via 18 and thus the paint container
At 11, the paint is forced to circulate so that a constant amount of paint of the desired viscosity is stored. This makes it possible to control the amount of paint to be supplied from the cylindrical roll 10 to the piston only by adjusting the rotational speed of the cylindrical roll 10, and the controlled supply amount is extremely stable. Further, in order to control the solid component amount per unit volume in the paint having the same viscosity with higher accuracy, it is necessary to make the fluctuation range of the temperature of the paint in the paint tank 15 as small as possible. It is appropriate to set the temperature within a temperature range in which the fluctuation range of the paint viscosity with respect to the temperature change is small (for example, in FIG. 9, it corresponds to a portion where the gradient of the graph is small). On the other hand, if the paint temperature is set too high, the amount of evaporation of the solvent will increase through the liquid surface of the paint in the paint container 11 that is open to the atmosphere, so the temperature is set within the range of 10 to 40 ° C. Is appropriate.

As shown in FIG. 10, in the paint container 11, substantially,
An example in which a scraper 25 is provided so as to extend over the entire width of the cylindrical roll 10 is shown. This scraper 25 is designed to be able to peel off the paint film remaining on the cylindrical roll 10 after transferring the paint to the piston, but here, as described above, the coating film is applied only to the convex part of the skirt part of the piston. Since the coating film is formed on the outer peripheral surface of the cylindrical roll 10 corresponding to the concave surface portion of the skirt portion, the coating film that has not been transferred remains after transfer, for example, referring to FIG. If this residual paint film is left as it is, the paint film is further laminated on the outer peripheral surface of the cylindrical roll 10 as shown in FIG. The residual paint film is in various laminated states depending on the peripheral speed ratio of the piston and the cylindrical roll 10 or the number of rotations thereof. For example, in FIG. The transfer pattern in the case of rotating is shown in a developed state. In the case of this example, when the coating film is transferred by rotating the piston once, the cylindrical roll 10 is further transferred onto the residual paint film at the first rotation between the first and the 1.5th rotations. The paint film of is laminated. Such a residual paint film not only significantly impairs the uniformity of the paint film on the outer peripheral surface of the cylindrical roll 10 required to form a uniform coating film on the piston, but also during the rotation of the cylindrical roll 10. The solvent evaporates from the paint film in the part of the paint container 11 exposed from the liquid surface of the paint, and the film thickness and viscosity of the paint film are locally nonuniform. Against this problem, as shown in FIG. 11, the scraper 25 rotates from the cylindrical roll 10 when the cylindrical roll 10 rotates and the portion once exposed to the atmosphere is again immersed in the paint in the paint container 11. The residual paint film is peeled off, whereby a paint film having a uniform film thickness and viscosity can always be formed on the exposed portion that should come into contact with the piston for transfer. The scraper 25 is composed of an elastic thin plate made of synthetic resin such as Teflon or polypropylene, or a thin plate made of stainless steel or phosphor bronze, and remains by applying a uniform radial pressing force along the axial direction of the cylindrical roll 10. It is possible to completely remove the paint film, but it is also possible to further apply elastic pressure of the spring to the scraper 25. Although the accuracy of the film thickness of the coating film formed on the piston can be greatly improved by the scraper 25, for example, in the case where the coating film is formed with the film thickness set value of 7 μm, it is formed when the scraper 25 is provided. The average value of the film thickness was 7.9 μm, whereas the average value was 9.2 μm when the scraper 25 was not provided.

FIG. 15 shows another example of the paint supply system for the paint container 11. According to this example, an overflow pipe 26 is connected between the paint container 11 and the paint tank 15 of the paint viscosity adjusting device, and the overflow port 26a of the overflow pipe 26 in the paint container 11 is surrounded to surround the overflow port 26a.
A cover 27 that defines a small chamber 27a is provided on the liquid surface of the coating material including. As described above, the paint in the paint container 11 is forcibly circulated by the paint viscosity adjusting device, but since the overflow port 26a is opened so as to keep the liquid level of the paint container 11 at a desired level, the paint container The immersion depth of the cylindrical roll 10 immersed in the paint in 11 can be kept constant, whereby a uniform paint film is formed on the cylindrical roll 10 rotating at a constant speed. The overflow pipe 26 allows the excess paint in the paint container 11 to be removed from the paint tank 15
It is preferable that the inner diameter of the overflow pipe 26 is large in order to reduce the line resistance of the overflow pipe 26 when flowing out. However, in such a case, the paint flows along the inner peripheral surface of the overflow pipe 26, and the paint does not fill the overflow pipe 26 and forms a cavity in the central portion thereof. This cavity accelerates the evaporation of the solvent in the paint through the air contact surface of the paint flowing in the overflow pipe 26, resulting in an unnecessarily high viscosity of the paint and the dry and solidified paint of the overflow pipe. Although there may be a problem that the inner diameter of the overflow pipe 26 becomes substantially small by adhering to the inner peripheral surface of 26, provision of the cover 27 prevents evaporation of the solvent in the paint and fixation of the paint. Can be prevented. As a result, the flow of the paint in the overflow pipe 26 can be smoothed, and the liquid level of the paint can be effectively retained. Incidentally, the cover 27 may be provided with a small hole 27b for degassing as shown in FIG.
As shown in FIG. 17, the overflow pipe 26 is connected to the paint container 11
May be connected via the side wall of the.

18 and 19 show a method of supporting a piston by a supporting roller. Here, a support roller 28 is further provided, which is capable of rollingly contacting the outer peripheral surface of the crown portion of the piston when the piston comes into contact with the cylindrical roll 10 to hold the piston at the contact position with the cylindrical roll 10. By the way, as shown in an example thereof by FIG. 23, the convex surface portion of the skirt portion of the piston is usually formed intermittently along the circumferential direction thereof, and when the cylindrical roll 10 makes a rotary contact with the piston, The convex surface portion and the concave surface portion are brought into contact with each other in accordance with the formation pattern of the convex surface portion, but particularly when the convex surface portion is changed to the concave surface portion or from the concave surface portion to the convex surface portion, a rotational contact due to a radial step between the two There is a problem in that there is rattling inside and smooth rotation cannot be performed. Further, not only does the peripheral edge of the convex surface make a dent on the outer peripheral surface of the cylindrical roll 10 due to the impact at the time of the transfer, or the paint is formed on the coating film formed on the piston by the cylindrical roll 10, There is also an inconvenience that the paint is transferred to the concave portion. Since the support roller 28 is supported so that a gap of about 30 to 500 μm is formed between the crown surface of the piston and the convex surface of the piston in contact with the cylindrical roll 10, When the transfer is performed on the convex surface portion, the gap does not hinder the contact between the convex surface portion and the cylindrical roll 10. or,
When the piston moves from the convex portion to the concave portion, the piston falls at most by this gap and approaches the cylindrical roll 10, but at this time, the support roll 28 rolls on the outer peripheral surface of the crown portion to support the piston, and The piston can no longer access the cylindrical roll 10. When the convex surface portion is further moved, the convex surface portion and the cylindrical roll 10 are brought into contact with each other again. Since the support roll 28 holds the piston in a constant contact position during the rotation of the piston in this way, the rotary contact between the piston and the cylindrical roll 10 is performed extremely smoothly, and the dents and the like as described above are generated. As a result of which generation can be completely eliminated, a uniform and smooth coating film is formed on the piston.

Although the example of the engine piston is described as the coated cylindrical body in the above-described embodiment, the present invention can be applied to coating of a coated object having a generally cylindrical shape and can exhibit the same operational effects as described above. Further, the specific numerical values and the like in the above description are not necessarily limited to them, and needless to say, can be appropriately selected as necessary.

〔The invention's effect〕

As described above, according to the present invention, a coating film having excellent coating film characteristics can be formed to efficiently perform this type of coating,
In particular, since the damper device is provided, the operation of the device can be performed smoothly and the work efficiency can be improved. Further, there are advantages that the usage rate of the paint can be increased to almost 100%, and the masking work can be eliminated altogether. Since the coating is performed by the transfer method, the work environment is not contaminated by the diffusion of paint particles and solvent gas, and the booth for painting is not required, and a small amount of local exhaust can sufficiently cope with the problem. In addition to allowing numerical control of coating conditions, the installation space for coating equipment is small,
The number of man-hours for cleaning and maintenance of the painting equipment can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view of a coating apparatus for carrying out the method for coating a cylindrical body according to the present invention, FIG. 2 is a partially cutaway perspective view of a paint container storing paint, and FIG. 3 is a coated cylinder. Side view showing the contact allowable range in the contact between the piston and the cylindrical roll as an example, FIG. 4 and FIG. 5 are side views showing the one-sided contact state of the piston and the cylindrical roll, and FIG. 6 is the present invention. FIG. 7 is a block diagram showing the basic steps of a coating method according to FIG. 7, FIG. 7 is a schematic diagram of a paint supply system for a paint container, FIG. 8 is a graph showing an example of the relationship between the dilution ratio and viscosity of paint, and FIG. 9 is paint. Is a graph showing an example of the relationship between the temperature and the viscosity, FIG. 10 is a partially cutaway perspective view showing the scraper provided in the paint container, FIG. 11 is a side longitudinal sectional view of the scraper, and FIG. The piston outer peripheral surface showing the relationship between the paint film and the transfer pattern Open views, FIGS. 13 and 14 are partial vertical cross-sectional views of a cylindrical roll for explaining a process of forming a residual paint film, FIG. 15 is a vertical cross-sectional view showing an overflow pipe connected to a paint container, and FIG. And FIG. 17 is a view showing a modified example of the overflow pipe, FIGS. 18 and 19 are side and front views showing a method of supporting a piston by a support roller, and FIG. 20 is a concave portion of a skirt portion of the piston. A front view showing a contact state with a cylindrical roll, FIG. 21 is a side view of a piston as a cylindrical body to be coated, FIG. 22 is a perspective view of a main part of a coating apparatus showing a conventional spray coating method, FIG. (A), (B) and (C) is a development view showing an example of a pattern of the outer peripheral surface of the piston. 1 ... Base, 2 ... Lifting / driving means, 5 ... Rotation axis, 7,
12 …… Drive motor, 9 …… Vacuum pad, 10 …… Cylindrical roll, 11 …… Paint container, 15 …… Paint tank, 16 …… Metric pump, 19 …… Automatic viscosity controller, 22 …… Solvent tank, 25 …… scraper, 26 …… overflow pipe, 27…
… Cover, 28 …… Supporting roller.

Claims (5)

[Claims] 1. A coated cylinder rotatably mounted around a horizontal axis and movably up and down, and around an axis parallel to the coated cylinder at a position near the lower side of the coated cylinder. A rotatably mounted cylindrical roll, a paint container capable of storing paint so that a part of the peripheral surface of the cylindrical roll is immersed below the cylindrical roll, and the coated cylinder And a damper device for applying a braking force to the coated cylindrical body before coming down and coming into contact with the cylindrical roll, in a state where the coated cylindrical body and the cylindrical roll are in contact with each other. A coating device for a cylinder such as an engine piston, which is adapted to apply the paint in the paint container to the surface of the cylinder to be painted by rotating independently. 2. A scraper that extends substantially over the entire width of the cylindrical roll in the paint container and removes the paint remaining on the cylindrical roll, and a paint viscosity in the paint container that is constant. A paint viscosity adjusting device for keeping,
A pump connected to the paint viscosity adjusting device is further provided so that the paint in the paint container can be circulated through the paint viscosity adjusting device.
The coating device described in. 3. An overflow pipe connected between the paint container and the paint viscosity adjusting device for maintaining a constant liquid level in the paint container, and an overflow pipe surrounding the overflow port of the overflow pipe. The coating apparatus according to claim (2), further comprising: a cover defining a small chamber on the surface of the coating liquid including the overflow port. 4. The coating apparatus according to claim 3, wherein the cover is provided with a ventilation hole. 5. A support roller is further provided which, when the coated cylinder contacts the cylindrical roll, rolls on the outer peripheral surface of the coated cylinder to hold the coated cylinder at the contact position with the cylindrical roll. The coating apparatus according to any one of claims (1) to (4).