JPS61197078A - Powder coating method - Google Patents

Abstract

PURPOSE:To form efficiently a thick-coated film on the surface of a material by introducing hot air into the metallic cylindrical material to be coated and coating powder while heating the material. CONSTITUTION:Holes 3a for ejecting hot air heated by a gas burner 10 are provided to a hollow shaft 3. The hot air flowing into the hollow shaft 3 flows out from each ejection hole 3a and hence a metallic cylindrical material 1 to be coated is heated. Then the coating nozzle 11 of a thermal spray coater is reciprocated to sprinkle the powder 12 made of a synthetic resin over the material 1 to be coated. In this case, the heating temp. of the material 1 to be coated can be easily controlled by the regulation of the supply of a gas to the gas burner 10 which is the hot air source. Namely, the material 1 to be coated is evenly heated at a constant temp. at all times. Consequently, a coated film having optional and uniform thickness can be easily formed on the surface of the material to be coated while rotating the material and by controlling the time of coating.

Description

Detailed Description of the Invention <a> Industrial Application Field The present invention, when forming a coating film on a heated object, efficiently heats the object to be coated to form a thick film on the surface of the object. The present invention relates to a powder coating method capable of forming a coating film. More specifically, the present invention relates to a powder coating method that can form a thick coating film on the surface of a metal cylindrical object while efficiently heating the object by introducing hot air into the object.

(b) Conventional Technology Powder coating is a coating method in which a powdered synthetic resin is sprinkled onto the surface of the object to be coated and heated to form a coating film.

Powder coating is characterized by the fact that the paint is in powder form and is completely solvent-free, and it is attracting the most attention as a pollution-free and resource-saving coating method, and is rapidly becoming popular. And, as a method for coating powder,
Fluid immersion coating method, electrostatic coating method, electrostatic dynamic immersion coating method,
There are thermal spray coating methods, etc.

In either method, the thickness of the coating film formed is mostly determined by the heating temperature and heat capacity (amount of heat storage) of the object to be coated, but in the case of thin objects to be coated, the heat capacity of the object is small; In addition, in the case of large objects to be coated, the time required for moving from the heating process to the painting process and the time required for the powder coating process are long, so the object to be coated is cooled during that time, resulting in -1 heating process and powder coating process. 1 in the body painting process, at most 1 mL 1
It is possible to form a film of only a certain thickness.

However, for joints, junction box covers, etc. used for long-term anti-corrosion durability coatings or high voltage insulation applications, powder coatings with a thickness of 31 to 5 mm are often required. In such cases, a coating film having the above-mentioned thickness was formed by repeating the heating process and the powder coating process.

However, this method not only complicates the coating process, but also, in the case of long or large objects, the object must be heated above the melting point of the powder to be coated using a heating device. Since it takes time to transfer the object into the apparatus and the object to be coated, once heated, is cooled during that time, the film formed per coat is thin and the efficiency of the coating operation is extremely low.

In addition, when repeatedly heating and powder coating the object to be coated, foreign matter may get mixed into the coating film, or the surface of the existing coating may deteriorate due to heat and an interface may be formed between the coated coatings. There were also disadvantages in terms of coating film properties such as

(c) Means for solving the problem The powder coating method of the present invention heats the object by introducing hot air into a cylindrical object that is long, large, or has a small heat capacity. A thick coating film is formed on the surface of the object by powder coating.

That is, the present invention involves introducing hot air into a metal cylindrical object to be coated, thereby applying powder coating while heating the object to be coated, thereby forming a coating film on the surface of the object to be coated. This is a characteristic feature.

In the present invention, a cylindrical shape includes various shapes such as a circular cross section, and a rectangular shape includes an elliptical shape, and the outer shape also includes a straight, curved, branched, or curved outer shape. In short, it is sufficient that the shape is cylindrical and allows hot air to flow through it.

As a source of hot air that can be used in the present invention, combustion heat of flammable gas such as propane gas, butane gas, city gas, or liquid fuel such as kerosene can be used.Instead, electric Joule heat can be used. etc. can also be used.

Then, air heated by such a heat source may be sent using a blower or the like.

In forming a coating film on the surface of the object to be coated, the temperature and flow rate of the hot air should be determined by taking into account the melting point of the composite resin powder and the coating workability. in this case,
The temperature of the hot air can be controlled very easily by controlling the fuel supply status and electric current, and the flow rate of the hot air can be easily adjusted using a throttle valve, and the combination of these two makes it possible to always heat the object to be coated under constant conditions.

The hot air supply device may be directly inserted into the cylindrical object to be coated, or alternatively, it may be provided outside the object to be coated, but this may affect the painting workability or the object to be coated. In order to always heat the object to be coated under constant conditions, the hot air supply device is preferably provided outside the object to be coated.

The present invention can be applied to any method such as a fluidized dip coating method, an electrostatic coating method, an electrostatic dynamic dip coating method, or a thermal spray coating method. This method is suitable because the temperature can be lowered compared to other coating methods, and a thick coating film can be formed efficiently.

(d) Function In the present invention, hot air is used as a heat source for powder coating, and the temperature of the hot air can be adjusted extremely easily by adjusting the fuel supply state and electric current.

By introducing hot air heated to a constant temperature into the cylindrical object to be coated, the object to be coated can always be maintained at a constant temperature. By controlling the time, a coating film of any thickness can be formed on the surface of the object to be coated.

(e) Examples Examples of the present invention will now be described in detail based on the drawings.

In the figure, (1) is a cylindrical object to be painted installed horizontally, and a cover (2) (2) is attached to both ends of the object (1) to be painted.
is removably attached, and the object to be coated (1) is supported by a hollow shaft (3) that protrudes from both ends thereof and passes through the double force bar unit (2) (2), and the hollow shaft (3)
Both ends of the machine are rotatably supported by a pair of rollers (6) (6) provided at both ends of the machine base (4) (5), and the rollers (6) are driven via a drive chain (7). By being rotated by the motor (8), the object to be coated (1) is rotated by the hollow shaft (
3) is configured to rotate around the center.

In addition, (9) and (9) are stoppers, and each stopper (
9), the object to be coated (1) is fixed to the hollow shaft (3).

The hollow shaft (3) is provided with respective blow-off holes (3a) for air (hot air) heated by the svarna (10), and the hot air flowing into the hollow shaft (3) is disposed in the blow-off holes (3a). 3
a) flows out, thereby heating the object (1) to be coated.

The cover unit (2) is provided with a discharge hole (2a) for hot air flowing in from the hollow shaft (3).

(11) is a coating nozzle of a thermal spray coating machine;
) is manually or mechanically reciprocated to sprinkle synthetic resin powder (12) onto the object (1) to be coated.

Next, a method for coating the powder (12) on the surface of the object to be coated (1) will be explained.

As described above, the object to be coated (1) is heated by the hot air guided to the hollow shaft (3) and discharged from the blow-off hole (3a). In this case, the heating temperature of the object to be coated (1) can be easily controlled by adjusting the amount of fuel gas to the burner (10) of the hot air generation source. After the object to be coated (1) is heated to a predetermined temperature, the object to be coated (1) is.

While being rotated by the motor (8), the paint 7 zuru (1
According to step 1), the surface is powder coated, but the time required for coating can be set arbitrarily, and therefore a coating film of any thickness can be formed.

The object to be coated (1) that has been powder coated is baked in a heating furnace if necessary, and then coated with stoppers (9) (9).
, the hollow shaft (3) and the cover (2>(2)).

The above example is a case where the present invention is applied to a cylindrical object to be painted (1), but the present invention is not limited thereto, and the present invention is not limited to this. Needless to say, it may be applied to objects to be painted, or objects to be painted that have bends or branches, and hot air may also be blown directly into the object to be painted (1) without passing through the hollow shaft (3). In order to further improve thermal efficiency, hot air may be circulated.

It goes without saying that the powder coating method can be applied not only to the thermal spray coating method but also to other powder coating methods.

(f) Detailed Description of the Invention As described in detail, the present invention allows the object to be coated to be heated at a constant temperature and evenly by blowing hot air whose temperature has been controlled in advance into the object. By controlling the coating, a uniform coating film of any thickness can be extremely easily formed on the surface of the object to be coated.

Further, by sending hot air directly into the object to be coated, thick coating films can be efficiently powder coated, and the amount of fuel required for heating can be reduced, thereby reducing the cost of the entire coating process.

Further, since the present invention heats the cylindrical object to be coated while sending hot air thereto, no special equipment or techniques are required, and equipment costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an apparatus suitably employed in the method of the present invention, FIG. 2 is a cross-sectional view taken along the line ■--■, and FIG. 3 is a side view. (1)...Object to be coated (3)...Hollow shaft (12)...Powder

Claims (1)

[Claims] (1) By introducing hot air into a metal cylindrical object to be coated, the object to be coated is heated and powder coated to form a coating film on the surface of the object to be coated. Powder coating method.