JPH08112565A - Coating method - Google Patents

Abstract

PURPOSE: To obtain a uniformly distributed coating film at the time of arranging >=3 bell-shaped coating guns almost on a straight line and reciprocating the guns in the arranging direction to coat a material. CONSTITUTION: Three or more bell-shaped coating guns 4 are arranged above a car body W almost on a straight line when an automobile is coated or the like, and the guns 4 are reciprocated in the arranging direction to coat the car body W. In this case, the discharge of coating material from the intermediate gun 4 is reduced as compared with the discharge of coating material from the guns 4 on both sides, and a coating film is formed in uniform thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating method for coating a vehicle body of an automobile by reciprocating three or more bell-type coating guns in the arrangement direction.

[0002]

2. Description of the Related Art Conventionally, for example, in painting a vehicle body of an automobile, a plurality of painting guns are arranged on a straight line in a direction orthogonal to the carrying path above a carrying path of a vehicle carried by a carrying device, and the painting guns are arranged. There is known a coating method in which a moving vehicle body is painted while reciprocating in a certain direction. For example, Japanese Patent Application Laid-Open No. 1-297169 is an improvement of this coating method, in which the mutual spacing of a plurality of coating guns can be adjusted so that the coating width can be freely changed.

[0003]

However, in the conventional general coating method including the above-mentioned technique, since the paint discharge amounts of a plurality of coating guns are all set to the same value, the coating film in the middle portion is applied to the end portion. It tends to be thicker.

[0004]

In order to solve the above-mentioned problems, the present invention has three or more rotary atomization type coating guns arranged substantially on the same straight line, and the rotary atomization type coating guns are arranged along the arrangement direction. In the coating method in which the gun is reciprocated, the amount of paint discharged from the middle part of the rotary atomizing type coating gun is smaller than the paint discharged from the coating guns on both ends. I did it. The rate of reduction depends on the coating material and other coating conditions. For example, if there are three coating guns, the amount of coating material discharged from the central coating gun is reduced by about 5 to 30%.

[0005]

[Function] Generally, there is paint that escapes outside the coating range in the coating guns at both ends, but there is little paint that escapes outside the coating range in the middle part, and static electricity distribution and air flow that occur in each coating gun. It is considered that the thickness of the coating film in the middle portion becomes thick due to the relationship of the flow of. Therefore, it is attempted to form a uniform coating film by reducing the amount of coating material discharged from the coating gun in the middle portion by this thickening amount.

[0006]

Embodiments of the coating method of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a schematic diagram of an automobile coating apparatus adopting the present coating method, and FIG. 2 is a schematic explanatory diagram of a coating pattern by a coating gun. In the coating process of an automobile body, as shown in FIG. 1, a coating device 2 is used to coat a vehicle body W conveyed by a conveying device 1. The coating device 2 is directed toward the upper side of the vehicle body W. The arm 3 is extended, and three bell-shaped coating guns 4 are arranged on the arm 3 at predetermined intervals. The bell-type coating gun 4 is capable of reciprocating in a direction orthogonal to the carrying path of the vehicle body W, and is adapted to spray paint downward.

The bell type coating gun 4 rotates a bell type rotating disc at a high speed and spreads the paint supplied to the central portion in the outer peripheral direction along the inner surface of the rotating disc by the action of centrifugal force. Is applied in a tangential direction to the paint, and at the same time charges are applied to the paint and shaping air is blown around the paint to adjust the paint pattern, and is generally used as a coating method with high coating efficiency. Then, as shown in FIG. 2, the peripheral portion of the coating pattern of the coating gun 4 becomes a dust portion having a low coating density, and the coating guns 4 and 4 which are adjacent to each other are formed.
Between them, the dust parts overlap each other to form a dust concentration part, the paint density is lower than the pattern part and the paint density is higher than the dust part.

Therefore, when coating is performed on the upper surface of the vehicle body W while reciprocating the bell type coating gun 4 along the arrangement direction, when the coating material discharge amount is the same, the film thickness distribution shown in FIG. As shown in the schematic diagram, the film thickness t ₁ at the central portion becomes thicker than the film thickness t ₂ at both ends. This phenomenon is caused by the fact that the paint patterns at both ends have dust parts that escape to the outside of the coating range, whereas the paint pattern in the middle has less paint that escapes to the outside of the coating range, and the static electricity generated in each coating gun 4 It is considered to be caused by the distribution and the relationship of the air flow.

[0009] Therefore, less than both end portions of the paint discharge amount of the center of the spray gun 4 in merits, the thickness t ₁ of the film thickness t ₂ and an intermediate portion of the end portion as shown in the film thickness distribution schematic diagram of FIG. 3 Try to make it uniform. The amount to be reduced varies depending on various coating conditions and the like, but it is preferable to reduce the amount by about 5 to 30%.

The above is an example in which the number of the coating guns 4 is 3, but when the number of the coating guns 4 is 4, as shown in FIG. It is desirable to set the amount to “medium” and the paint discharge amount of the intermediate coating guns 4 and 4 to “small”. Further, when the number of the coating guns 4 is 5,
As shown in (B), the paint discharge amount of the coating guns 4 and 4 at both ends is set to “medium”, or the paint discharge amount of the coating guns 4 and 4 and 4 in the middle part is set to “small”, or Preferably (C)
As shown in, the paint discharge amount of the coating guns 4 and 4 at both ends is set to “many” and the paint discharge amount of the coating guns 4 and 4 inside thereof is set to “medium”, and the paint discharge amount of the middle coating gun 4 is set. It is effective to reduce the number.

Next, a specific verification result will be described based on (Table 1).

[Table 1]

First, the coating color symbol A (coating color name: silver metallic 1) contains 4.7% aluminum (no coloring pigment) as a bright pigment, and a metallic composition consisting of other components such as resin, solvent and additives. As for the paint, three bell type coating machines 4, ... At this time, the coating was divided into two passes, one pass and two passes, and the interval was set to 80 sec. And in the first pass, coating guns 4 and 4 (G-1, G-) on both ends
The paint discharge rate of 3) is set to 95 cc / min, the paint discharge rate of the central coating gun 4 (G-2) is set to 85 cc / min, about 10% reduction, and the rotation speed of the coating gun 4 is set to 20%. 1,000
Painted as a spin. Then, in the second pass, the paint discharge rate is set to 10,0 under the same conditions as in the first pass.
It was lowered to 00 rpm and painted. As a result, the target film thickness 13μ
Was coated with a film thickness of 12 to 14 .mu.

Similarly, the coating color symbol B (coating color name: silver metallic 2) is a metallic paint composed of 5.5% aluminum as a bright pigment, 0.5% coloring pigment, and other resin components, solvents, additives and the like. There is also a paint discharge rate of 125cc / m for the coating guns 4 and 4 (G-1, G-3) at both ends.
When the paint discharge rate of the central coating gun 4 (G-2) was reduced to 100 cc / min by about 20% with respect to in, two-pass coating was performed, and the coating film distribution was uniformed to 5: 5.

Further, the paint color code C (paint color name: red pearl)
Is a metallic paint consisting of a colored P of 5.9% as a bright pigment, 2.8% of a colored pigment, and other resin components, solvents, additives, etc., and the coating guns 4 and 4 (G- 1 and G-3) paint discharge rate 130cc / min, the central paint gun 4 (G-2) paint discharge rate is 12
When two passes were applied at 0 cc / min, which was a little less than 10%, the distribution of the coating was uniformed to 5: 5. Of course, the paint is not limited to the metallic paint, but is applicable to solid paint and the like.

Incidentally, the first pass is rotated at a relatively high speed, and
The reason why the pass is set to a relatively low speed is to rotate at a high speed to a certain extent in the first pass to blow away volatile components such as solvents from the sprayed paint components to rapidly increase the viscosity and to produce bright pigments such as aluminum flakes. Suppresses random movements,
Further, by stabilizing the hardness of the lower layer at an early stage, the bright pigment in the second pass can be easily oriented, and by making the second pass relatively slow, the arrangement of the bright pigment can be improved.

[0016]

As described above, the coating method according to the present invention is
In a coating method in which three or more coating guns are arranged on substantially the same straight line and coating is performed while reciprocating the coating guns along the arrangement direction, the paint discharge amount of the coating gun in the middle part Since the coating amount is smaller than the discharge amount, it is possible to apply a uniform film thickness.

[Brief description of drawings]

[Figure 1] Schematic diagram of an automobile coating device that uses this coating method

[Fig. 2] A schematic explanatory view of a coating pattern by a coating gun.

[Fig. 3] Schematic diagram of coating film distribution in the coating method of the present invention

FIG. 4 is a schematic diagram of a coating film distribution in a conventional coating method.

FIG. 5 is an explanatory diagram illustrating an example of a paint discharge amount when four and five coating guns are used.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Conveyor device, 2 ... Coating device, 3 ... Arm, 4 ... Bell type coating gun, W ... Vehicle body.

Claims (1)

[Claims] 1. Three or more rotary atomizing type coating guns are arranged on substantially the same straight line, and the rotary atomizing type coating guns are reciprocally moved along the arrangement direction to coat an object to be coated. In the coating method described above, the amount of paint discharged from the intermediate coating gun of the rotary atomization type coating gun is smaller than the amount of paint discharged from the coating guns located at both ends.