JP2013154322A - Electrostatic coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic coating apparatus capable of increasing coating efficiency, thereby minimizing wasteful coating.SOLUTION: For example, a conductive primer coating zone is divided into rough blow coating and regular blow coating. A voltage of -30 KV is applied between a coating gun 5 for rough blow and a workpiece W, and a voltage of -60 KV is applied between a coating gun 6 for regular blow and the workpiece W. In performing rough blow coating, an applied voltage is low; therefore, electrostatic repulsion is little and thin and uniform coating is formed. Subsequently, the applied voltage for regular blow coating is increased, so that coating particles firmly adhere to an already formed coating film. At this time, by reversing the rotational direction of a hanger 7 in rough blow coating and regular blow coating, a more uniform coating film is provided.

Description

  The present invention relates to an electrostatic coating apparatus that applies a conductive primer with an upstream electrostatic coating machine and then performs a top coating with a downstream electrostatic coating machine.

  Electrostatic coating is generally performed as a method for coating parts of automobiles and motorcycles. In this electrostatic coating, a high voltage is applied between the paint gun and the work to ionize the paint particles sprayed from the paint gun, and electrostatically adsorb the paint particles to the work charged on the opposite side. The paint particles wrap around and are painted even on the inner surface of the workpiece.

  As the electrostatic coating method, a method disclosed in Patent Document 1 is known. In this patent document 1, a reciprocator (coating machine) is arranged on one side of a hanger conveyor that suspends and conveys a workpiece, and a workpiece provided in the reciprocator grips the hanger conveyor so that the workpiece and the reciprocator are synchronized. During this time, the workpiece is electrostatically coated.

  Patent Document 2 describes the contents of attaching a large number of workpieces to a rotating body and rotating the rotating body while moving the rotating body.

JP-A-06-000421 Japanese Patent Laid-Open No. 08-057374

The number of application guns used for undercoating and topcoating is often 2-4. However, the number of these application guns is not controlled individually even if they are plural.
In addition, when electrostatically applying a conductive primer, when a high voltage is suddenly applied, there is a problem that the paint particles ejected later are repelled (electrostatic repulsion) due to the same charge by the ionized paint particles ejected earlier. .

In order to solve the above-mentioned problems, the present invention provides an electrostatic coating apparatus in which a plurality of zones are provided along a conveyance line of a workpiece that is an object to be coated, and an electrostatic coating machine is disposed in each zone. At least one is divided into a rough spraying application zone and a main spraying application zone. In the rough spraying application zone, a voltage applied between the coating gun and the work is applied to the main spraying application gun and the work. It was set as the structure set smaller than the voltage concerning between.
Examples of the zone include a conductive primer application zone and a topcoat zone (base coat and top coat).

  As a more specific configuration, a hanger that rotates about a vertical axis in a state where a plurality of workpieces are suspended is provided on the conveyance line, and the coating gun can reciprocate in the conveyance direction and the vertical direction of the workpiece. It is attached to an electrostatic coating machine (reciprocator).

  In rough spray coating and main spray coating, it is preferable to reverse the rotation direction of the hanger for uniform coating. It is preferable to apply both the conductive primer coating zone and the overcoating zone to reverse the rotation direction of the hanger.

In addition, it is preferable that the electrostatic coating machine moves up or down in one painting process and the hanger is rotated a plurality of times. Although depending on the conditions, good results were obtained at 15 times / min in the examples.
In this way, the coating pattern is ideal in that the inclination angle and width of the coating strip ejected from each coating gun is constant and no gap is formed between the coating strips ejected from the adjacent coating gun. A coating pattern can be formed.

According to the electrostatic coating apparatus according to the present invention, the coating efficiency can be significantly increased as compared with the prior art, and the waste of paint is reduced.
In addition, since there is no gap in the coating pattern, the thickness of the paint applied to the workpiece becomes uniform.

Overall configuration diagram of electrostatic coating apparatus according to the present invention The perspective view explaining the details of the conductive primer application zone A diagram explaining the change in applied voltage during rough spray coating and main spray coating The figure which shows the application pattern when the operation of the application gun is made only once ascending or descending when the work is suspended in a cylindrical shape Figure showing the application pattern when the work of the application gun is reciprocated up and down when the work is suspended in a rectangular shape (A) And (b) is the figure explaining the difference when the workpiece is suspended so as to form a cylindrical shape and when the workpiece is suspended so as to form a rectangular shape.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The electrostatic coating apparatus according to the present invention is provided with a conductive primer coating zone and an overcoating zone along the conveying line L of the workpiece W that is an object to be coated, and the top coating zone is further divided into a base coat zone and a top coat zone. .

  1 and 2, Z1 represents a conductive primer rough blowing zone, and Z2 represents a conductive primer main blowing zone. The top coating zone is provided on the downstream side of the main blowing zone Z2. Electrostatic coating machines 1 and 2 are disposed in each of the zones Z1 and Z2. In this embodiment, the electrostatic coating machines 1 and 2 apply the conductive primer, but the structure is the same, and one electrostatic coating machine is reciprocated along the transport line, and one of them is omitted. It is also possible.

  Also, in the base coat zone and top coat zone constituting the top coat zone, the forward coating and reverse coating are performed using an electrostatic coating machine, and then robot coating and human coating are performed. In robot painting, four sides are painted, and in human painting, painting is performed at low speed.

The electrostatic coating machine 1 will be described below.
The electrostatic coating machine 1 applies a coating gun 5 for rough spraying and a coating gun 6 for main spraying to the arm 4 of the reciprocator 3 that reciprocates in the vertical direction and in the direction along the conveyance line (conveyor) L of the workpiece W. Are spaced along the transfer line L. In the embodiment, two rough spraying application guns 5 and two main spraying application guns 6 are provided, but the number is arbitrary.

The workpiece W is attached to the hanger 7. The hanger 7 is provided with a plurality of horizontal arms extending radially, and the work W is locked to the horizontal arm so that the whole is substantially cylindrical.

Further, a sprocket 8 is attached to the shaft of the hanger 7, and the sprocket 8 is rotated by a chain 10 (timing belt) that runs by a motor 9 arranged corresponding to each zone. That is, when the hanger 7 enters each zone, the sprocket 8 and the chain 10 are engaged with each other, and the hanger 7 moves along the transport line L and rotates.

In the present invention, rough spray coating and main spray coating are performed in the conductive primer coating zone, but rough spray coating and main spray coating can also be performed in the top coating zone.

As shown in FIG. 3, generally, in electrostatic coating, a high voltage is applied between the workpiece and the application gun. In this embodiment, between the coating gun 5 for rough spraying and the workpiece W, Applies a voltage of −30 kv, and a voltage of −60 kv is applied between the main spray gun 6 and the workpiece W.

Since the applied voltage is small during rough spray coating, there is little electrostatic repulsion, and a thin and even coating film is formed. Thereafter, by increasing the applied voltage in the main spray coating, the paint particles adhere firmly to the already formed coating film.
At this time, a more uniform coating film can be obtained by reversing the rotation direction of the hanger 7 in the rough spray coating and the main spray coating.

FIG. 4 is a diagram illustrating an example of coating in the main blowing zone Z2. In this embodiment, the coating gun 6 slowly rises or falls during painting and does not reciprocate up and down. Further, the hanger 7 rotates a plurality of times (preferably 10 times or more) during that time.

In this way, the coating gun 6 is moved at a low speed in one direction upward or downward, and the hanger 7 to which the workpiece is attached is rotated a plurality of times during that time. The application pattern in this case is shown in the lower part of FIG. The application pattern assumes that a cylindrical screen is set in front of the application gun 6 instead of the hanger, and two application guns 6 are provided in series.

By moving the application gun 6 in one direction (either upward or downward) in one application process and rotating the hanger (screen), the application area of the paint discharged from the application gun has a constant inclination angle. It is represented by a band-like area with Then, by controlling the width of the paint discharged from the application gun, an application pattern with less overlap with the application area of the adjacent application gun can be obtained.

FIG. 5 shows an example for comparison with FIG. 4. In this example, the workpiece W is suspended on each surface of a rectangular hanger, and the coating gun 6 is moved up and down 1.5 times during one coating. Was reciprocated. In this case, there is a portion where the paint is not applied to the application pattern, and the problem of uneven application occurs.
Therefore, it is preferable that the application gun 6 moves slowly upward or downward without reciprocating during one application.

FIG. 6A shows a state in which the workpiece W is suspended in a shape close to a cylinder, and FIG. 6B shows a state in which the workpiece is suspended from a rectangular side in plan view. As is clear from this figure, when the work is suspended so that the whole becomes a rectangular shape, the paint particles go around the back side of the work because of the electrostatic coating, but the paint particles go around the side of the adjacent work. There may be cases where the paint does not spread sufficiently.
On the other hand, when the workpiece is suspended in a shape close to a cylinder, the space between adjacent workpieces spreads, and the paint is easily supplied to the side surface and the back surface.

The electrostatic coating apparatus according to the present invention according to the present invention can be used by being incorporated into an automated two-wheeled vehicle or automobile coating line.

DESCRIPTION OF SYMBOLS 1, 2 ... Electrostatic coating machine, 3 ... Reciprocator, 4 ... Arm, 5, 6 ... Application gun, 7 ... Hanger, 8 ... Sprocket, 9 ... Motor, 10 ... Chain 10 (timing belt), W ... Workpiece, L ... conveying line, Z1 ... conductive primer rough blowing zone, Z2 ... conductive primer main blowing zone.

Claims (4)

  In an electrostatic coating apparatus in which a plurality of zones are provided along a conveyance line of a workpiece that is an object to be coated, and an electrostatic coating machine is disposed in each zone, at least one of the plurality of zones is a coating zone for rough spraying The voltage applied between the coating gun and the workpiece is set to be smaller than the voltage applied between the coating gun and the workpiece for the main blowing. An electrostatic coating apparatus characterized by   2. The electrostatic coating apparatus according to claim 1, wherein the transport line is provided with a hanger that rotates about a vertical axis in a state where a plurality of workpieces are suspended, and the coating gun is disposed in a workpiece transport direction and a vertical direction. An electrostatic coating apparatus characterized by being attached to a reciprocator capable of reciprocation.   The electrostatic coating apparatus according to claim 2, wherein the rotation direction of the hanger is reversed between rough blowing and main blowing. 3. The electrostatic coating apparatus according to claim 2, wherein, during the rough spraying or the main spraying, the electrostatic coating machine performs either a rising or a falling movement, and the hanger rotates a plurality of times. A feature of electrostatic coating equipment.

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