JP3828960B2 - How to paint a bumper - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bumper coating method for coating a bumper having a concavo-convex complex shape portion by selectively injecting air from an annular air outlet formed in a multiplex manner around a rotary atomizing head.
[0002]
[Prior art]
In general, as a coating device that applies a high voltage directly to a coating material, for example, a conductive coating material to apply electrostatic coating to an object to be coated such as an automobile body, the coating material is applied by the action of centrifugal force from the leading edge of the rotary atomizing head. There is known a rotary atomizing coating apparatus that emits water.
[0003]
By the way, in this kind of rotary atomizing type coating apparatus, the diameter of the coating pattern of the paint discharged from the rotary atomizing head is relatively large. For this reason, when the shape of the object to be coated is complicated, there is a problem in that the paint cannot be reliably applied to the portion of the object to be painted that is required to be painted.
[0004]
Therefore, for example, as disclosed in Japanese Patent Application Laid-Open No. 7-24367, it is possible to inject a plurality of rows of shaping air having different injection directions concentrically with respect to the rotation shaft to which the atomizing head is attached. A rotary atomizing electrostatic coating method is known in which the coating pattern width is variable by controlling the injection of shaping air in each row in accordance with the coating site.
[0005]
Specifically, as shown in FIG. 8, a shaping air nozzle 2 is disposed on the outer periphery of the atomizing head 1, and the shaping air nozzle 2 includes a number of first air passages communicating with the first air passage 3. An air outlet 4 and a number of second air outlets 6 communicating with the second air passage 5 are formed. The injection direction of the shaping air A1 injected from the first air outlet 4 is set in the twist direction with respect to the rotation center O1, while the injection direction of the shaping air A2 injected from the second air outlet 6 Is set parallel to the rotation center O1. Therefore, the shaping air A1 ensures a large coating pattern width, and the shaping air A2 ensures a small coating pattern width.
[0006]
[Problems to be solved by the invention]
However, in the above prior art, as shown in FIG. 8, the injection direction of the shaping air A <b> 2 is directed to the tip edge 1 a of the atomizing head 1. For this reason, even if the twisting effect of the shaping air A1 is reduced by the injection of the shaping air A2, the coating pattern width of the paint released from the atomizing head 1 cannot be effectively reduced. Therefore, it is difficult to effectively adapt to an object having a complicated shape.
[0007]
Thus, when painting the bumper 7 having the complicated shape portion shown in FIG. 9, although there is not much trouble in the painting work of the flat portion 7a, the paint is applied to the back of the lattice portion 7b and the molding portion 7c which are the complicated shape portions. It cannot be supplied effectively. As a result, as shown in FIGS. 10A and 10B, uncoated portions 8a and 8b are formed, and paint pools 9a and 9b are generated at the edge portions, making it difficult to perform high-quality painting work. The problem of becoming is pointed out.
[0008]
The present invention solves this type of problem, and an object thereof is to provide a bumper coating method capable of efficiently and efficiently coating a bumper having a complicated shape portion.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention injects air from only one annular air outlet, so that this air acts as shaping air, and is applied to a flat part other than the complicated part of the bumper. Work is given. On the other hand, the added air is added to the air from the one annular air outlet, and the air is injected from one or more other annular air outlets toward the front end of the rotary atomizing head. Acts as assist air. Therefore, the coating pattern width of the paint discharged from the rotary atomizing head can be effectively narrowed, and the paint is effectively supplied to the back of the lattice part and the molding part which are complex shaped parts, and at the edge part. It is possible to reliably prevent the occurrence of paint pools.
[0010]
In addition, in a complicated shape portion, the coating speed of the central portion of the coating pattern of the paint to be released increases, and the film thickness of the central portion increases. Therefore, when painting a complex-shaped part, the paint is applied in a state where a voltage lower than the applied voltage of the paint applied to the flat part is applied or in a non-applied state. For this reason, a change in color tone due to a change in the coating application speed can be effectively prevented.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic internal configuration explanatory view of a rotary atomizing electrostatic coating apparatus (electrostatic coating gun) 10 for carrying out a bumper coating method according to an embodiment of the present invention, and FIG. 1 is a schematic side view of an atomizing electrostatic coating apparatus 10. FIG.
[0012]
The rotary atomizing electrostatic coating apparatus 10 includes a casing 12, and a rotary atomizing head 18 is attached to the tip of a rotary shaft 16 of a motor 14 disposed in the casing 12. The rotary shaft 16 is formed in a hollow shape, and a paint passage 20 for supplying paint, for example, conductive paint, is formed in the inner peripheral surface of the rotary atomizing head 18.
[0013]
A shaping air cap 22 and an assist air cap 24 are screwed to the front end of the casing 12 so as to surround the rotary atomizing head 18. First and second screw portions 28a and 28b are provided on the outer periphery of the shaping air cap 22 with the flange portion 26 interposed therebetween. The first screw portion 28a is screwed into the casing 12, while the second screw portion 28b is The screw portion 30 is screwed into the screw portion 30 formed on the inner periphery of the assist air cap 24.
[0014]
The shaping air cap 22 has a first air passage 32 spaced apart by a predetermined angle in the circumferential direction, and one end side of the first air passage 32 communicates with an air supply source via a passage (not shown) in the casing 12. The other end side of the first air passage 32 communicates with the first annular air outlet 34, and the first annular air outlet 34 is directed to the front end edge 18 a of the rotary atomizing head 18 and the first annular air 36 </ b> A. In order to inject, the opening of the shaping air cap 22 opens in a ring shape.
[0015]
A plurality of ports 38 are formed on the outer periphery of the assist air cap 24 at a predetermined angular interval, and the pipes 40 connected to the ports 38 communicate with an air supply source (not shown).
[0016]
A second annular air outlet 44 communicates with the port 38 via a second air passage 42. The second annular air outlet 44 is directed further forward (a position ahead of the tip edge 18a by a distance H in FIG. 1) than the tip edge 18a of the rotary atomizing head 18 and toward the axis O of the rotary shaft 16. In order to inject the second annular air 46A in the direction of convergence (the direction inclined by the angle α °), a ring shape is formed between the outer periphery on the front end side of the shaping air cap 22 and the inner periphery on the front end side of the assist air cap 24. It is configured. In the present embodiment, the second annular air ejection port 44 is set in a direction inclined by 30 ° or 45 ° toward the axis O as an angle α °.
[0017]
The casing 12 houses high voltage application means (not shown) for charging the conductive paint discharged from the rotary atomizing head 18 with static electricity. It is attached to the arm and moved along a previously taught trajectory.
[0018]
The operation of the rotary atomizing electrostatic coating apparatus 10 configured as described above will be described below in relation to the bumper coating method according to this embodiment.
[0019]
First, the conductive paint is supplied to the rotary atomizing head 18 through the paint passage 20, and the rotary atomizing head 18 is rotated at a high speed under the action of the motor 14 and supplied to the rotary atomizing head 18. A high voltage is applied to the conductive paint through high voltage applying means (not shown). At that time, air is supplied to the first air passage 32 via an air supply source (not shown), and the leading edge 18a of the rotary atomizing head 18 is communicated from the first annular air outlet 34 communicating with the first air passage 32. The first annular air 36 </ b> A is jetted in the direction.
[0020]
Accordingly, the first annular air 36A acts as shaping air, and the conductive paint discharged from the rotary atomizing head 18 is applied to the bumper 7 with a predetermined application pattern P1 (pattern diameter D1) (see FIG. 3A). ). Therefore, as shown in FIG. 4, the conductive paint charged with static electricity forms an application pattern P1 in an atomized state and is sprayed on the flat portion 7a of the bumper 7, and electrostatic coating is performed on the flat portion 7a. .
[0021]
Further, when air is supplied to the pipe line 40 via an air supply source (not shown), air is supplied from the second air passage 42 communicating with the pipe line 40 to the second annular air jet port 44. Thereby, the second annular air 46A is jetted from the second annular air outlet 44 in a direction that is directed further forward than the tip edge 18a of the rotary atomizing head 18 and converges toward the axis O of the rotary shaft 16. .
[0022]
The second annular air 46A acts as assist air, narrowing down the pattern width of the conductive paint released from the rotary atomizing head 18 (the pattern diameter is reduced from D1 to D2), and the coating pattern P2 is obtained. (See FIG. 3B). The conductive paint is sprayed on the lattice portion 7b, which is a complex shape portion of the bumper 7 with the application pattern P2, and the molding portion 7c with the application pattern P2 ′, and is applied to the back of the lattice portion 7b and the molding portion 7c (see FIG. 4).
[0023]
That is, when the second annular air 46A is jetted toward the tip edge 18a of the rotary atomizing head 18, the pattern width of the conductive paint discharged from the rotary atomizing head 18 cannot be reduced. In practice, only a pattern width similar to that obtained when only the first annular air 36A was jetted was obtained.
[0024]
On the other hand, in the present embodiment, the second annular air 46A is directed further forward than the tip edge 18a of the rotary atomizing head 18 and is injected in a direction that converges toward the axis O of the rotary shaft 16. As shown in FIG. 5, the wind speed around the central portion of the coating pattern P2 of the conductive paint to be discharged (coating speed) was reduced by about 1 m / sec to 2 m / sec. In addition, as shown in FIG. 6, by using the second annular air 46A, the film thickness of the central portion of the coating pattern P2 of the conductive paint to be discharged is considerably thicker than other portions.
[0025]
Therefore, the pattern width of the conductive paint to be discharged can be greatly reduced, the wind speed at the center of the conductive paint coating pattern P2 (P2 ') can be increased, and the film thickness can be increased. . For this reason, it is possible to effectively supply the conductive paint to a coating portion having a complicated shape, for example, the back of the lattice portion 7b and the molding portion 7c, and to reliably prevent the occurrence of paint accumulation at the edge portion. There is an advantage.
[0026]
Specifically, an experiment for comparing the coating state between the case where the second annular air 46A is not used (hereinafter referred to as a conventional gun) and the case where the second annular air 46A is used (hereinafter referred to as an implementation gun). Went. The conventional gun coating conditions were 10m / sec for the first annular air 36A, 30,000 rpm (20,000 rpm for the second application), and a second application with a discharge rate of 82 g / min. In addition to the above-described conventional gun coating conditions, the assist pressure by the second annular air 46A was set to 1 kPa.
[0027]
As a result, in the conventional gun, as shown in FIG. 7A, the coating film P is formed on the flat portion Sa of the workpiece S, but the conductive paint is not supplied to the bent portion (angle 70 °) Sb, and it is not painted. Site R has been present. On the other hand, in the implementation gun, as shown in FIG. 7B, the desired coating film P was reliably formed from the flat portion Sa of the workpiece S to the bent portion Sb.
[0028]
In addition, when spraying the second annular air 46A in addition to the first annular air 36A, the conductive paint is applied to the flat portion 7a by spraying only the first annular air 36A. It is desirable that a voltage lower than the applied voltage is applied or no voltage is applied. In the conductive paint coating pattern P2, the wind speed at the center of the coating pattern P2 increases, so the applied voltage is lowered or maintained in a non-applied state to effectively change the color tone due to the change in the coating speed of the conductive paint. This is because it is necessary to prevent it.
[0029]
As a result, in the present embodiment, the bumper 7 can be painted with high quality and efficiency, and various complicated shapes can be obtained simply by ON / OFF switching control of the air assist by the second annular air 46A. It is possible to easily cope with the coated part of the film and to obtain an effect of excellent versatility.
[0030]
【The invention's effect】
As described above, in the bumper coating method according to the present invention, the air injected from one annular air outlet acts as the shaping air, and the coating operation is performed on the flat portion of the bumper. On the other hand, the coating pattern of paint that is added to the air from the one annular air outlet and the air injected from one or more other annular air outlets acts as assist air and is discharged from the rotary atomizing head The width can be effectively reduced.
[0031]
As a result, it is possible to effectively supply the paint to the back of the lattice part and the molding part, which are complex-shaped parts, and to reliably prevent the occurrence of paint accumulation at the edge part. Accordingly, it is possible to efficiently coat the entire bumper having a complicated shape portion with high quality and to obtain an effect of excellent versatility.
[Brief description of the drawings]
FIG. 1 is a schematic internal configuration explanatory view of a rotary atomizing electrostatic coating apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic side view of the rotary atomizing electrostatic coating apparatus.
FIG. 3 is an explanatory diagram of a coating pattern of paint released from the rotary atomizing electrostatic coating apparatus;
FIG. 3A is an explanatory diagram of an application pattern of only shaping air,
FIG. 3B is an explanatory diagram of a coating pattern when assist air is jetted.
FIG. 4 is an explanatory diagram when a bumper is coated with the rotary atomizing electrostatic coating apparatus.
FIG. 5 is a relationship diagram between a wind speed of only the shaping air and a wind speed when the assist air is applied.
FIG. 6 is a relationship diagram between the film thickness of only the shaping air and the film thickness when the assist air is applied.
FIG. 7 is an experimental example for comparing paint states;
FIG. 7A is an explanatory diagram of a state of painting with a conventional gun,
FIG. 7B is an explanatory diagram of a state of painting by an implementation gun.
FIG. 8 is an explanatory diagram of a schematic configuration of a coating apparatus according to a conventional technique.
FIG. 9 is a perspective explanatory view of a bumper which is an object to be coated.
FIG. 10 is a partial sectional view of the bumper;
FIG. 10A is a cross-sectional explanatory view of the lattice portion,
FIG. 10B is a cross-sectional explanatory view of the molding part.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Rotary atomization type electrostatic coating apparatus 12 ... Casing 16 ... Rotary shaft 18 ... Rotary atomization head 20 ... Paint passage 22 ... Shaping air cap 24 ... Assist air cap 32 ... 1st air passage 34 ... 1st annular air jet Outlet 36A, 46A ... annular air 40 ... pipeline 42 ... second air passage 44 ... second annular air jet outlet

Claims (1)

Using a rotary atomizing electrostatic coating gun with multiple annular air jets to inject air around the rotary atomizing head that discharges paint, paint bumpers with irregularly shaped parts A painting method,
While a high voltage is applied to the paint, by spraying air only from the annular air outlet that is opened in a ring shape, while applying a coating on a flat portion other than the complex shape portion of the bumper,
In a state where a voltage lower than the applied voltage is applied to the paint or in a non-applied state, it is added to the air from the one annular air outlet, and is directed forward from the tip edge of the rotary atomizing head. In the state where the coating pattern width of the paint discharged from the rotary atomizing head is further narrowed by injecting air from one or more other annular air outlets opened in a ring shape, A method of painting a bumper, characterized in that painting is performed on the complex shape portion.

Images