JPH02222743A - Method and equipment for coating cylindrical body such as piston for engine - Google Patents

Abstract

PURPOSE:To accurately perform coating of such a cylindrical body to be coated as the piston for engine without waste of coating by independently rotating a cylindrical roll in such a state that the cylindrical body to be coated is brought into contact with the cylindrical roll and applying coating housed in a coating vessel to the surface of the cylindrical body to be coated. CONSTITUTION:One part of the circumferential surface of a cylindrical roll 10 is immersed under the liquid surface of coating in a coating bath and rotated. A cylindrical body A (e.g. a piston for an engine) to be coated is rotated around the axial line parallel to the central line of the roll 10. The circumferential surface of this cylindrical body A is brought into contact with the circumferential surface of the roll 10. Thereby the coating film formed on the circumferential surface of the roll 10 is transferred on the circumferential surface of the cylindrical body A only at one layer. After this transfer, the contact of the cylindrical body A and the roll 10 is cut off. As a result, coating of such the cylindrical body to be coated as this kind can be efficiently and accurately performed without waste of coating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coating method and apparatus suitable for coating the outer peripheral surface of a cylindrical body having holes or convex portions on the outer peripheral surface, such as an engine piston.

[Conventional technology]

Fig. 21 shows an example of an engine piston. In the case of this piston, a solid lubricant coating is formed on the outer peripheral surface of the skirt portion to facilitate sliding contact with the inner wall surface of the cylinder. It has the effect of being able to As a result, the initial break-in time of the engine can be significantly shortened to about 10% or less, and vibrations and noise during operation can be reduced, and fuel efficiency can be improved. Conventionally, a spray method as shown in FIG. 22 has been adopted for painting such engine pistons. As shown in the figure, the piston, whose crown part is fitted into a support and whose piston pin hole is sealed with a masking plug, is sprayed with paint by a spray gun or the like while rotating, and a paint film is formed only on the skirt part. It was becoming like this.

Furthermore, a convex surface portion to which a coating film is to be applied is formed as a sliding surface on this skirt portion, as shown in FIG. 23(A).

(B) and (C) show typical examples of the patterns of the convex portions, but since it is originally sufficient to form a coating film only on such convex portions of the skirt portion, other than the convex portions The region (hereinafter referred to as the concave surface portion) is appropriately masked when spraying with a spray gun.

[Problem to be solved by the invention]

In such conventional spray painting methods, most of the paint sprayed from the spray gun not only adheres to supports other than the convex surface portions, masking plugs, etc., but also scatters into the air, resulting in significant paint waste.

For this reason, the coating rate of the paint is extremely low at around 20%, and in addition, the paint adhering to the supports, etc. is subjected to calcination treatment together with the painted piston in the subsequent process, so that it does not coat the surfaces of the supports, etc. Gradually, the paint accumulated, and it was necessary to frequently remove the accumulated paint, which was a tedious task. In addition, masking work for concave surfaces is time-consuming,
Therefore, productivity is inevitably lowered, and furthermore, since the method is a spray method, there are problems such as contamination of the working environment due to fine paint particles scattered.

In view of the above circumstances, it is an object of the present invention to provide a coating method and a coating device that can efficiently and accurately coat this type of cylindrical body without wasting paint. shall be.

[Means and effects for solving the problems] In the coating method according to the present invention, a cylindrical roller is attached to the circumferential surface of a cylindrical roll, which is rotated by immersing a portion of the circumferential surface under the surface of the paint liquid in a paint bath. By bringing the circumferential surface of the cylindrical body rotated around an axis parallel to the center axis of the roll into contact with each other, the paint film formed on the circumferential surface of the cylindrical roll is applied to the circumferential surface of the cylindrical body to be coated in just one layer. After this transcription, contact between the parties is cut off. Further, the cylindrical body to be coated may be preheated before contact with the cylindrical roll, and the cylindrical body to be coated may be continuously rotated after transfer.

Because it is a transfer-based coating, it is possible to form a coating film with a uniform thickness without scattering the paint, but at this time, the fixation of the transferred paint is improved by preheating the cylindrical body to be coated. Furthermore, by rotating the cylindrical body to be coated after transfer, dripping of the paint can be prevented.

Further, the coating apparatus according to the present invention includes a cylindrical body to be painted which is mounted to be rotatable around a horizontal axis and movable up and down, and a cylindrical body to be painted which is mounted at a position close to the bottom side of the cylindrical body to be rotatable around a horizontal axis and movable up and down. It includes a rotatably mounted cylindrical roll, and a paint container capable of storing paint so that a part of its circumferential surface is immersed in the lower side of the cylindrical roll.

Therefore, by rotating the cylindrical body to be painted and the cylindrical roll independently while in contact with each other, the paint in the paint container can be applied to the surface of the cylindrical body to be painted.

The coating device further includes a scraper for peeling off paint remaining on the cylindrical roll in the paint container, a viscosity adjustment device for the paint in the paint container, or a viscosity adjustment device for the paint in the paint container connected between the paint container and the viscosity adjustment device. An overflow pipe may be provided to keep the paint liquid level constant, and these can further improve coating film properties such as film thickness. In addition, by providing a damper device that can apply a braking force during the downward movement of the cylindrical body to be coated into contact with the cylindrical roll, and a support roller that holds the cylindrical body to be coated in a position of contact with the cylindrical roll, the apparatus can be improved. It is possible to make the operation smoother and achieve a uniform coating film.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a cylindrical body coating method and coating apparatus according to the present invention will be described below with reference to FIGS. 1 to 6. still,
This embodiment is an example of an engine piston shown in FIG. 21 in the description of the prior art as a cylindrical body to be coated.

First, the coating apparatus of the present invention will be explained. In FIG. 1, 1 is a base, and 2 is a cylinder to be coated, which is made of an air cylinder, etc., which is vertically attached to a frame 1a that stands up from the base l. 3 is a slide table that is moved up and down by the lift drive means 2; 4 and 4' are a board 3 attached horizontally to the upper end of the slide table 3;
A plummer block 5 is fixedly installed on the plummer block 4, 5 is a rotating shaft that is supported by the plummer block 4, 4' and has a through hole 5a for vacuuming inside, 6 is attached to one end of the rotating shaft 5. 7 is a drive motor that can rotate the rotary shaft 5 via the transmission gear 6; 8 is a drive motor that is attached to the other end of the rotary shaft 5 and is fitted with the crown portion of the piston as shown in the figure; 9 is a vacuum pad mounted inside the holder 8 so as to be in close contact with the upper end surface of the crown portion of the piston; 10 is a frame body 1a, la' A cylindrical roll 1) is mounted under the cylindrical roll IO so that its axis is parallel to the axis of the piston at a position close to the bottom of the piston via a support shaft 10a rotatably supported. This is a paint container (see FIG. 2) in which paint can be stored so that a part of the surface of the cylindrical roll IO is immersed in the paint container. The piston is brought into contact with the cylindrical roll 10 as described below, with FIG. 3 showing a preferred state of contact between the two. That is, the skirt portion of the piston is not a right cylinder (it has a drum shape curved in the longitudinal direction by several tens of microns, and strictly speaking, it makes point contact with the outer peripheral surface of the cylindrical roll 10. Therefore, as shown in FIGS. If there is uneven contact at either end of the skirt as shown in Figure 5, the thickness of the paint film will be inappropriate or the paint will not be transferable.
Therefore, the contact point between the two is set to occur at the center of the skirt portion as shown in FIG. Furthermore, 12 is a drive motor capable of rotating the cylindrical roll 10 via a universal joint 13 etc., and 14 is a drive motor of the slide table 3 so as to apply a braking force to the piston immediately before the piston contacts the cylindrical roll 10. This is a damper device that starts to come into contact with the lower end.

Next, an example of a coating method for forming a coating film on a piston using the apparatus configured as described above will be explained. FIG. 6 shows the basic process. It will be preheated.

This preheating step can improve the fixation of the paint that is subsequently transferred to the skirt, but the temperature is below 100 DEG C., preferably in the range of 80 DEG to 85 DEG.

Here, a mixture of a solid lubricant made of molybdenum disulfide and PTFE and a binder such as polyamideimide is used as the paint, but the paint viscosity is in the range of 13 to 90 secFC#4 to obtain good coating properties. be. The preheated piston is fitted into the holder 8 which is raised by the lifting drive means 2 via the slide table 3 of the coating device, and is fixed to the holder 8 by being evacuated via the vacuum vat 9. be held. Next, the piston is lowered to come into contact with the cylindrical roll IO, which forms a uniform paint film with the paint in the paint container 1) and is rotating in a constant direction at a constant speed. Damper device 1 just before
4 comes into contact with the lower end of the slide table 3 and applies a braking force to the downward movement of the piston, so that the impact caused by the collision that occurs when the piston is brought into sudden contact with the cylindrical roll 10 is applied to the piston and the cylindrical roll 10. It is possible to prevent the parallelism between the axes from being lost or from creating dents 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 begins to rotate at a constant speed in the same direction as the rotational direction of the cylindrical roll IO. Figure 2)
This starts the transfer to the convex surface of the piston skirt. The convex surface of the piston and the outer peripheral surface of the cylindrical roll 10 are in line contact, and the transfer starting point is selected so that the contact area is minimized, that is, the position corresponding to the piston pin hole. is optimal.

By the way, regarding the relationship between the circumferential speed of the piston, the circumferential speed of the cylindrical roll IO, and the thickness of the coating film to be formed, in the case of the piston, the smaller the circumferential speed is, the faster the cylindrical roll I
In the case of O, the larger the circumferential speed, the larger the film thickness tends to be in each case, and therefore, the ratio of both circumferential speeds is an important factor that affects coating film properties, especially film thickness. This circumferential speed is determined by the diameter and rotation speed, but the diameter of the cylindrical roll 10 is determined by reducing the contact area with the atmosphere of the part exposed to the atmosphere from the liquid surface of the paint container It. In order to prevent the solvent from evaporating from the paint film formed on the outer peripheral surface, it is preferable to make the diameter smaller. Therefore, if it corresponds to the specific diameter of the piston to be painted, the above-mentioned circumferential speed ratio should be set within a certain optimum range, and this condition is set for each individual piston.

By rotating the piston once while maintaining contact with the cylindrical roll 10 from the transfer start point, the paint film of the cylindrical roll IO is transferred only to the convex surface of the skirt portion, forming a single layer of paint film.

In this case, if the circumferential speed, contact pressure, etc. of the piston and the cylindrical roll 10 are set appropriately, the coating film on the piston formed by transfer has a uniform film thickness and a smooth coating surface. and exhibits extremely excellent coating properties. After the transfer, the piston is raised by the lift drive means 2 via the slide table 3, etc. In this case, the damper device 14 urges the piston upward, so that the piston immediately moves into the cylindrical shape after the transfer is completed. shape roll 10
You can withdraw from contact with. In this way, the action of the damper device 14 allows the piston and the cylindrical roll IO to come into contact and separate from each other accurately and quickly, which is advantageous in making the coating uniform when transferring with rotation. be.

Note that this damper device 14 may be configured using an air damper, a coil spring, or the like.

Then, the painting (transfer) process is completed, and then the drying process begins (see Figure 6), which is carried out by continuing to rotate the piston for a predetermined period of time by the drive motor 7 after the piston has been raised. be exposed.

In this way, it is possible to prevent the fluid coating film from sagging after transfer and to uniformly fix the coating film on the convex surface of the piston. In this case, it is preferable to When heated in an atmosphere of 150° C. or lower, the formed coating film can be finished even more smoothly. Also, by blowing hot air onto the coating surface of the piston, the time required for the drying process can be significantly shortened, but the temperature of the hot air is 2.
The temperature is preferably 00° C. or lower, and the wind speed is suitably 3 m/sec or lower in order to prevent so-called ripples from occurring on the surface of the coating film due to wind pressure. Note that during this time, the cylindrical roll 10 may be continued to be 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 a baking furnace. The baking conditions at this time vary slightly depending on the characteristics of the paint, but are generally 180
C/60 minutes to 230'C/30 minutes.

According to the coating method consisting of the basic steps described above, a uniform and smooth coating film is formed only on the convex surface of the piston skirt, but since no paint adheres to any areas other than the convex surface, paint is not wasted. Completely eliminate paint usage rate by almost 10%
It becomes possible to set it to 0%. Further, it is possible to eliminate the need to contaminate the working environment due to paint scattering, etc., or to clean adhering paint, as in the case of the above-mentioned one-spray type, and work efficiency is improved.

FIG. 7 shows an outline of a system according to a second embodiment of the above coating apparatus. Here, the amount of paint supplied to the piston to form a coating film is controlled by adjusting the rotation speed of the cylindrical roll IO, and the amount of paint supplied is kept constant by such control. is necessary to form a uniform coating film. This supply amount is cylindrical roll IO
In the low rotation speed range, it is almost proportional to this rotation speed, but on the other hand,
The 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 dominated by the dilution rate of the paint with the solvent and the temperature. Therefore,
In order to keep the thickness of the paint film constant and to control the amount of paint supplied to the piston only by the rotation speed of the cylindrical roll 10, the paint container l in which the cylindrical roll IO is immersed is required.
It is necessary that a certain amount of paint with a constant viscosity is always stored in the tank. By the way, in FIG. 7, 15 is a paint tank having a sufficiently large volume for the paint container 1), and 16 is a pipe 17 for supplying the paint in the paint tank 15 to the paint container 1). A metering pump 18 is a pipe for returning excess paint in the paint container 1) to the paint tank 15, 19 is an automatic viscosity controller capable of detecting the viscosity of the paint in the paint tank 15, and 20 and 21 are provided as necessary. suitable stirrer and heat exchanger, 22
23 is a solenoid valve whose opening and closing can be controlled by a signal from the automatic viscosity controller 19; 24 is for supplying the solvent in the solvent tank 22 to the paint tank 15; It is a pipe. These components constitute a paint viscosity adjusting device.

In the coating apparatus of this second embodiment, the desired paint viscosity is preset in the automatic viscosity controller 19 and the paint tank 15
When a difference occurs between the viscosity of the paint in the paint tank 15 and the viscosity of the paint in the paint tank 15, a signal from the automatic viscosity controller 19 causes the solenoid valve 23 to open so that the viscosity of the paint in the paint tank 15 becomes the desired viscosity. Replenish. In this case, the stirrer 20
The viscosity of the paint throughout the paint tank 15 is made uniform, and the temperature of the paint can be appropriately adjusted by the heat exchanger 21. In addition, as a method of replenishing the solvent, use the solvent tank 2.
2 is installed at a higher position than the paint tank 15, and the solvent is dripped into the paint tank 15 through a pipe 24 by opening and closing a solenoid valve 23. In addition, a metering pump or the like is arranged in the middle of the pipe 24. The operation of this pump may be controlled by a signal from the automatic viscosity controller 19.

The paint in the paint tank 15 that has reached the desired viscosity is fed by a metering pump 16 to the paint container 11 via a pipe 17, while the excess paint in the paint container 1) is fed to the paint tank 15 via a pipe 18. The paint container 1 is returned to the paint container 1 like this.
), the paint is forced to circulate so that a constant amount of paint of a desired viscosity is always 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. Furthermore, in order to control the amount of solid components per unit volume in a paint having the same viscosity with higher precision, it is necessary to keep the range of fluctuation in the temperature of the paint in the paint tank 15 as small as possible. indicates the temperature range in which the range of variation in paint viscosity due to temperature changes is small (for example, in Figure 9, this corresponds to the part where the slope of the graph is small)
It is appropriate to set the temperature to . On the other hand, if the paint temperature is set too high, the paint container is exposed to the atmosphere.
Since the amount of solvent evaporation increases through the liquid level of the paint inside, it is therefore appropriate to set the temperature in the range of 10 to 40°C.

FIG. 1O shows an example in which a scraper 25 is provided within the paint container 1) so as to extend over substantially the entire width of the cylindrical roll 10, as shown. This scraper 25 is designed to remove the paint film remaining on the cylindrical roll IO after the paint is transferred to the piston, but as mentioned above, the paint film is only applied to the convex part of the skirt part of the piston. 13, the paint film that was not transferred remains on the outer peripheral surface of the cylindrical roll 10 corresponding to the concave portion of the skirt portion even after transfer. If this residual paint film is left as it is, a further paint film will be deposited on the outer peripheral surface of the cylindrical roll 1O as shown in FIG. 14. The residual paint film forms various layers depending on the circumferential speed ratio of the piston and the cylindrical roll 10 or their rotational speed. For example, in FIG. 12, the cylindrical roll lO is The transfer pattern is developed and shown when the transfer pattern is rotated by .5 rotations. In this example, when the piston rotates once and the paint film is transferred, between the 1st and 1.5th rotation of the cylindrical roll 10, the remaining paint film from the first rotation of the cylindrical roll 10 is transferred. Further, a paint film is laminated therebetween. Such a residual paint film not only significantly impairs the uniformity of the paint film on the outer peripheral surface of the cylindrical roll IO, which is necessary to form a uniform paint film on the piston, but also The evaporation of the solvent from the paint film in the parts exposed above the liquid surface of the paint in the paint container 1) makes the thickness and viscosity of the paint film locally non-uniform. To deal with this problem, 1) as shown in the figure, the scraper 25 is used to remove the cylindrical roll 10 when it rotates and the part once exposed to the atmosphere is immersed again into the paint in the paint container 1). The remaining paint film is peeled off from 10, thereby making it possible to always form a paint film having a uniform thickness and viscosity on the exposed portion that is to come into contact with the piston for transfer. The scraper 25 is made of an elastic thin plate made of a synthetic resin such as Teflon or polypropylene, or a thin plate made of stainless steel or phosphor bronze, and is applied with an even radial pressing force along the axial direction of the cylindrical roll 1o to remove residual residue. Although the paint film can be completely removed, it is also possible to apply spring pressure to the scraper 25. The accuracy of the thickness of the coating film formed on the piston by the scraper 25 can be greatly improved;
In an example where a coating film was formed with a thickness of μm, when the scraper 25 was installed, the average value of the film thickness formed was 7.9 μm, whereas when the scraper 25 was not installed, the average value was 9°2 μm. It is.

FIG. 15 shows a third embodiment of the coating apparatus according to the present invention.

In this embodiment, an overflow pipe 26 is connected between the paint container 1) and the paint tank 15 of the paint viscosity adjusting device, and an overflow pipe 26 is connected in the paint container 1).
A cover 27 is provided to surround the overflow port 26a of No. 6 and define a small chamber 27a above the paint liquid surface including the overflow port 26a. As described above, the paint in the paint container 11 is forced to circulate by the paint viscosity adjusting device, but since the overflow pipe 26a is opened to maintain the liquid level in the paint container 1) at a desired level, the paint The immersion depth of the cylindrical roll IO immersed in the paint in the container 11 can be kept constant, thereby forming a uniform paint film on the cylindrical roll 10 rotating at a constant speed. In order to reduce the resistance of the overflow pipe 26 when the excess paint in the paint container 11 is discharged into the paint tank 15 by the overflow pipe 26, it is more convenient to have a larger inner diameter. However, in such a case, the paint flows along the inner circumferential surface of the overflow pipe 26, and the paint does not fill the overflow pipe 26, creating a cavity in its center. This cavity promotes evaporation of the solvent in the paint through the air-contact surface of the paint flowing inside the overflow pipe 26. As a result, the viscosity of the paint becomes larger than necessary, and the dried and solidified paint flows into the overflow pipe. However, by providing the cover 27, the evaporation of the solvent in the paint and the adhesion of the paint can be prevented. Can be prevented. This smoothes the flow of the paint in the overflow pipe 26 and effectively maintains the paint level. Note that this cover 27 may be provided with a small hole 27b for degassing as shown in FIG. 16, and on the other hand, as shown in FIG. may also be connected.

FIG. 18 shows a fourth embodiment of the coating apparatus according to the present invention.

Here, a support roller 28 is further provided, which can roll into contact with the outer peripheral surface of the crown portion of the piston when the piston comes into contact with the cylindrical roll 10, and can hold the piston in a position of contact with the cylindrical roll IO.

By the way, as shown in FIG. 23, the convex surface of the skirt of the piston is usually formed intermittently along the circumferential direction, and when the cylindrical roll 10 comes into rotational contact with the piston, The convex part and the concave part are brought into contact according to the formation pattern of the convex part, but especially when transitioning from a convex part to a concave part or from a concave part to a convex part, rotational contact occurs due to the step difference in the radial direction between the two parts. There is a problem in that it causes rattling inside and cannot rotate smoothly.

Furthermore, due to the impact during the transition, the peripheral edge of the convex surface not only makes dents on the outer peripheral surface of the cylindrical roll 10, but also causes paint marks on the coating film formed on the piston by the cylindrical roll IO. There are also disadvantages such as the paint being transferred to the concave surfaces. The support roller 28 is supported so that a gap of about 30 to 500 μm is formed between the convex surface of the piston and the crown of the piston when the convex surface of the piston is in contact with the cylindrical roll IO. When transfer is performed on the convex surface portion, such a gap does not prevent the convex surface portion from contacting the cylindrical roll IO.

Furthermore, when the piston moves from the convex surface to the concave surface, it falls down by at most this gap and approaches the cylindrical roll 1o, but at this time the support roll 28 rolls into contact with the outer peripheral surface of the crown part and supports the piston. , so the piston can no longer approach the cylindrical roll lo. When the roller moves further to the convex surface portion, the convex surface portion and the cylindrical roll 10 come into contact again. Since the support roll 28 holds the piston in a constant contact position while the piston is rotating, the rotational contact between the piston and the cylindrical roll 1o is extremely smooth, and the dents and the like as described above are prevented. As a result of being able to completely eliminate this occurrence, the piston has a uniform
Moreover, a smooth coating film is formed.

Although an example of an engine piston has been described as the cylindrical body to be coated in each of the above embodiments, the present invention can be applied to coating a generally cylindrical body to be coated to exhibit the same effects as described above. Further, the specific numerical values and the like in the above description do not necessarily limit the scope of the present invention, and can of course be appropriately selected as necessary.

〔Effect of the invention〕

As described above, according to the present invention, a coating film having excellent coating properties can be formed and this type of coating can be performed efficiently.
In particular, it has the advantage of increasing the paint usage rate to almost 100% and eliminating the need for masking work at all.Since the painting is done by a transfer method, the work is done by the diffusion of paint particles and solvent gas. The environment will not be polluted (in addition, a painting booth will not be necessary and a small amount of local exhaust air will be enough to deal with the problem).Furthermore, in addition to making it possible to numerically control painting conditions, The installation space is small, and the number of man-hours for cleaning and maintenance of the coating equipment can be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view of a coating device for carrying out the method of 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 cylindrical body to be coated. FIG. 4 and FIG. 5 are side views showing a state of partial contact between the piston and the cylindrical roll, and FIG. 7 is a schematic diagram of a system according to the second embodiment of the coating apparatus of the present invention, and FIG. 8 is a graph showing an example of the relationship between the dilution rate and viscosity of the paint. Figure 9 is a graph showing an example of the relationship between the temperature and viscosity of paint, Figure 1O is a partially cutaway perspective view showing a scraper installed in a paint container, and Figure 1) is a side longitudinal sectional view of the scraper. , Figure 12 is a developed view of the outer peripheral surface of the piston showing the relationship between the residual paint film and the transferred pattern.
Figures 3 and 14 are partial vertical cross-sectional views of a cylindrical roll to explain the process of forming a residual paint film, Figure 15 is a vertical cross-sectional view showing an overflow pipe connected to a paint container, and Figures 16 and 17. Figure 1 shows a modified example of the overflow pipe.
8 and 19 are side and front views showing how the piston is supported by support rollers, FIG. 20 is a front view showing the state of contact between the concave surface of the piston skirt and the cylindrical roll, and FIG. 21 is a front view showing how the piston is supported by the support roller. A side view of a piston as a cylindrical body to be painted, FIG. 22 is a perspective view of the main parts of a coating device showing a conventional spray coating method, and FIGS. 23 (A), (B), and (C) are outer peripheral surfaces of the piston. FIG. 3 is a developed diagram showing an example of a pattern. l... Base, 2... Lifting drive means, 5...
・Rotating shaft, 7, 12... Drive motor, 9... Vacuum pad, 10... Cylindrical roll, 1)... Paint container, 15... Paint tank, 16... ...metering pump, 19...automatic viscosity controller, 22...
・Solvent tank, 25...Scraper, 26...
Overflow pipe, 27...Cover 28...
support roller. Figure 2 1?1 Figure 3 Figure 4F! ! Yu, ts Zuko 9 Paint 'JL Arashi (@C) 1P18 Figure 19? 20Figure 1-15Figure 1-16Figure 1P17Figure t22Figure

Claims (8)

[Claims] (1) A coating that is rotated around an axis parallel to the central axis of the cylindrical roll is placed on the circumferential surface of a cylindrical roll that is rotated with a portion of its circumferential surface immersed below the paint liquid level in a paint bath. By bringing the circumferential surface of the coated cylinder into contact, only one layer of the paint film formed on the circumferential surface of the cylindrical roll is transferred onto the circumferential surface of the to-be-coated cylindrical body, and after the transfer, the to-be-coated cylindrical body and the above-mentioned A method of painting cylindrical bodies, such as engine pistons, in which contact with the cylindrical roll is cut off. (2) The scope of the claim ( The coating method described in 1). (3) A cylindrical body to be painted that is rotatable around a horizontal axis and movable up and down, and rotates around an axis parallel to the cylindrical body to be painted at a position close to the bottom of the cylindrical body to be painted. a cylindrical roll mounted on the cylindrical roll, and a paint container capable of storing paint so that a part of the circumferential surface of the cylindrical roll is immersed in the lower side of the cylindrical roll, A coating device for a cylindrical body such as an engine piston, wherein the cylindrical body and the cylindrical roll are rotated independently while in contact with each other to apply the paint in the paint container to the surface of the cylindrical body to be coated. . (4) A scraper extending substantially over the entire width of the cylindrical roll in the paint container, for removing paint remaining on the cylindrical roll, and for keeping the viscosity of the paint in the paint container constant. Claims further comprising: a paint viscosity adjusting device; and a pump connected to the paint viscosity adjusting device, the paint in the paint container being circulated through the paint viscosity adjusting means. The coating device described in 3). (5) an overflow pipe connected between the paint container and the paint viscosity adjusting device for keeping the paint liquid level in the paint container constant; and an overflow pipe surrounding the overflow port of the overflow pipe. The coating apparatus according to claim (4), further comprising a cover defining a small chamber on the surface of the paint liquid containing the coating material. (6) The coating device according to claim (5), wherein the cover is provided with a ventilation hole. (7) Any one of claims (3) to (6), further comprising a damper device that applies a braking force to the cylindrical body to be coated immediately before the cylindrical body to be coated contacts the cylindrical roll. Painting equipment described in. (8) The cylindrical body to be coated further includes a support roller that rolls into contact with the outer peripheral surface of the cylindrical body to be coated when the cylindrical body to be coated comes into contact with the cylindrical roll to hold the cylindrical body to be coated in a position of contact with the cylindrical roll. , a coating device according to any one of claims (3) to (7).