JPH0899053A - Rotary atomizing head-type coating apparatus - Google Patents

Abstract

PURPOSE: To generate whirling current, enlarge a paint sprayed pattern with a small amount of air, and improve painting efficiency by making shaping air come into collision against a rotary atomizing head, regarding a rotary atomizing head-type coating apparatus. CONSTITUTION: Shaping air is jetted out toward the outer circumferential face 11A of a rotary atomizing head through an air jetting outlet 17 of a shaping air ring 14 in the direction C shown by an arrow and the air is changed into a whirling current in direction D shown by an arrow by each uneven groove 13 formed in the outer circumferential face 11A. A coating sprayed pattern can be enlarged by the whirling current even if the amount of the air is small by changing the shaping air into the whirling current and coating efficiency is improved while suppressing air pumping phenomenon and the coating quality can be heightened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary atomizing head type coating device used as an electrostatic coating device by, for example, a direct charging system or an indirect charging system.

[0002]

2. Description of the Related Art Generally, a rotary atomizing head type coating apparatus rotates a rotary atomizing head at a high speed and applies a high voltage between the rotary atomizing head and an object to be coated, thereby coating the smooth surface of the rotary atomizing head with paint. To atomize the paint by rotation and atomize the charged paint particles onto the object to be flight-coated along an electrostatic field formed between the object and the object in the axial direction. Has become.

As a rotary atomizing head type coating apparatus according to the prior art, a direct charging type electrostatic coating apparatus shown in FIG. 7 is known.

In the figure, reference numeral 1 denotes a coating machine main body mounted on a reciprocator (not shown). The coating machine main body 1 has an air bearing 2, an air motor 3, a paint valve (not shown) and the like built therein.

Reference numeral 4 denotes a rotary shaft that is rotatably supported by an air bearing 2. The tip of the rotary shaft 4 projects out of the main body 1 of the coating machine, and the base end side of the rotary shaft 4 is attached to an air motor 3. It is designed to be driven by high speed rotation.

Reference numeral 5 denotes a bell-shaped rotary atomizing head provided at the tip of the rotary shaft 4. The rotary atomizing head 5 has a cup-shaped outer peripheral surface 5A, an inner peripheral smooth surface 5B, and a tip. And the paint discharge edge 5C on the side.

Reference numeral 6 denotes a center feed type paint supply pipe which is provided so as to be inserted into the rotary shaft 4, and the tip of the paint supply pipe 6 extends toward the inside of the rotary atomizing head 5 and its base. A paint valve is provided on the end side, and the paint valve is connected to a paint tank (neither is shown) via a paint pipe.

Reference numeral 7 denotes a cover, which is made of an insulating resin so as to cover the outer periphery of the main body 1 of the coating machine.

Reference numeral 8 denotes a shaping air ring located at the tip of the main body 1 of the coating machine and fixed to the tip of the cover 7.
The shaping air ring 8 is composed of an outer ring portion 8A and an inner ring portion 8B that are provided so as to surround the rotary atomizing head 5, and a gap on the tip side between the respective ring portions 8A and 8B is air. It becomes the ejection port 8C and ejects shaping air in the direction of arrow A.

Reference numeral 9 denotes a high voltage cable, which connects the main body 1 of the coating machine and a high voltage generator (not shown) arranged outside the main body 1 of the coating machine.

In the conventional coating apparatus having the above-mentioned structure, the rotary shaft 4 and the rotary atomizing head 5 are formed by applying a high voltage to the main body 1 of the coating machine through the high voltage cable 9.
Is charged to a high voltage to form an electrostatic field with the object to be coated, and the rotary shaft 4 and the rotary atomizing head 5 are rotated at high speed by the air motor 3 in the main body 1 of the coater.

In this state, by opening the paint valve, the paint is supplied to the rotary atomizing head 5 via the paint supply pipe 6, and the supplied paint is centrifuged by the rotation of the rotary atomizing head 5. By the force, it spreads in a thin film shape on the paint smooth surface 5B and is directly contact-charged. Further, a very strong electric field is generated between the paint discharge edge 5C of the rotary atomizing head 5 and the object to be coated. At this time, due to the centrifugal force of the rotary atomizing head 5, the paint is atomized from the film into a liquid thread and from the liquid thread into particles (mechanical atomization) as it jumps radially outward from the paint discharge edge 5C. On the other hand, since the paint is charged at a high voltage, the surface tension is reduced, and because the paint is charged with the same sign, it repels and atomizes (electrostatic atomization). Then, the paint particles atomized in this way fly toward the direction of the electric field, that is, the object to be coated and are applied.

On the other hand, since the rotary atomizing head 5 is rotated at a high speed, the paint particles discharged from the paint discharging edge 5C by the centrifugal force tend to be blown outward in the radial direction. But,
Arrow A from air outlet 8C of shaping air ring 8
By the shaping air ejected in the direction, the discharged paint particles are patterned so as to be squeezed toward the front of the rotary atomizing head 5, and a paint spray pattern having a small diameter is formed as shown by the solid arrow B direction. Further, the shaping air collides with the film-shaped or liquid thread-shaped coating material discharged from the coating material discharge edge 5C to assist the atomization of the coating material.

[0014]

By the way, in the above-mentioned conventional rotary atomizing head type coating apparatus, the paint spray pattern is a donut pattern, and in order to eliminate the pattern of the hollow thin film, shaping air is applied to the paint discharge edge. 5C
Since the paint spray pattern is strongly collided with the paint, the paint spray pattern becomes a thick film with a small diameter, and there is a problem that the finish quality of the paint is deteriorated.

Further, in order to solve this problem, a method of ejecting the shaping air as a swirling flow from the shaping air ring is disclosed in JP-A-58-92475.
It is disclosed in Japanese Patent Laid-Open No. 3-101858.

These are those in which the direction of the outlet of the shaping air is arranged in a twisting direction with respect to the rotation axis of the rotary atomizing head, and in order to make the paint spray pattern a large-diameter thin film by this method, a large amount is required. However, there is a problem that the cost becomes high because of the need for the air.

Furthermore, when a large amount of air is used as the shaping air, a negative pressure is generated in the vicinity of the axial center of the rotary atomizing head 5, and this negative pressure causes an air pumping phenomenon. As a result, there is a problem in that the paint particles discharged from the rotary atomizing head 5 cause "flapping", and the coating efficiency on the object to be coated is significantly reduced.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention allows a swirl flow to be generated in front of a rotary atomizing head so that a wide coating spray pattern can be obtained with less shaping air. The present invention aims to provide a rotary atomizing head type coating device.

[0019]

According to a first aspect of the present invention, there is provided a rotary atomizing head type coating apparatus provided with a main body of a coating machine having an air motor therein and a tip end side of the main body of the coating machine which is rotatable by the air motor. A rotary atomizing head whose outer peripheral surface is cylindrical or cup-shaped and whose inner peripheral surface is a paint smooth surface and whose tip is a paint discharging edge, and which is located behind the rotary atomizing head and is more than the paint discharging edge. Air ejecting means for ejecting shaping air radially inward, and shaping air ejected from the air ejecting means that is formed on the outer peripheral surface of the rotary atomizing head and is on the paint discharge edge side of the rotary atomizing head. It is composed of a current changing portion that changes to a swirling flow in the front.

According to a second aspect of the present invention, the shaping is provided on the front end side of the main body of the coating machine so as to be positioned rearward of the paint discharge edge of the rotary atomizing head and to cover the outer peripheral rear portion of the rotary atomizing head. An air ring is provided, and the air jetting means is provided on the shaping air ring.

According to a third aspect of the present invention, the current-changing portion is formed by a concavo-convex body including a large number of grooves or blades formed on the entire outer peripheral surface of the rotary atomizing head.

[0022]

According to the first aspect of the present invention, the shaping air from the air jetting means is jetted to the outer peripheral surface radially inward of the paint discharge edge of the rotary atomizing head, and the shaping air is formed on the outer peripheral surface. Since the current is changed to a swirling flow in front of the rotary atomizing head by the current changing part, the paint spray pattern can be made large even if the shaping air is small, and the amount of air can be reduced. By adjusting the amount, the paint spray pattern can be made large in diameter when the amount of air is large, and can be adjusted appropriately by making the pattern small in amount when the amount of air is small.

According to a second aspect of the present invention, the coating machine main body is arranged such that the air jetting means is located rearward of the paint discharge edge of the rotary atomizing head and covers the outer peripheral side of the rotary atomizing head. Since it is formed on the shaping air ring provided on the tip side of the, the air can be applied as shaping air to the outer peripheral surface of the rotary atomizing head by ejecting the air from the air ejecting means.

According to the third aspect of the present invention, since the current-changing portion is formed on the outer peripheral surface of the rotary atomizing head as a concavo-convex body composed of a large number of grooves or blades, shaping air is caused to flow along the grooves or blades. As a result, even if the shaping air is small, the shaping air can be transformed into a swirling flow in front of the rotary atomizing head.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. In the embodiments, the same components as those of the above-described conventional technique are designated by the same reference numerals, and the description thereof will be omitted.

First, FIG. 1 and FIG. 2 show a first embodiment of the present invention.
An example of is shown.

In the figure, reference numeral 11 denotes a rotary atomizing head according to the present embodiment, which is provided at the tip of the rotary shaft 4. The rotary atomizing head 11 is formed as a cylindrical body whose tip is widened and whose front side is widened. Open part 1
1A1 and a cup-shaped outer peripheral surface 11A having a mounting portion 11A2 on the rear side, a paint smoothing surface 11B on the inner peripheral side, and a paint discharging edge 11C on the front end side. However, the rotary atomizing head 11 according to the present embodiment has a large number of concave and convex grooves 13 as concave and convex bodies, which will be described later, over the entire circumference of the outer peripheral surface 11A.
, ... Are formed at a constant pitch. Further, a disc-shaped hub member 12 is fixed to the rotary atomizing head 11 so as to close the tip side.

Here, as shown in FIG. 3, the hub member 12 has first hub holes 12A, 1 for guiding paint and thinner to the smooth surface 11B of the rotary atomizing head 11 on the outer peripheral side thereof.
A large number of 2A, ... Are formed, and for example, four second hub holes 12B, 12B, which supply thinner to the tip side at the center side,
Are formed (only two of each is shown).

Reference numerals 13, 13, ... Depict concave-convex grooves as current-changing portions.
The paint discharge edge 11 is located at the expanded portion 11A1 of 1A.
A large number are formed along the axial direction at a constant pitch within a range from C to about 1/2 of the expanded portion 11A1 and along the entire circumference thereof.

The arrow C shown in FIG. 1 ejected from the air ejection port 17 of the shaping air ring 14 described later.
Directional shaping air is rotating atomizing head 1 that rotates at high speed.
The rotary atomizing head 11 along each of the concave and convex grooves 13 formed in
As shown in FIG. 3, the swirling flow in the arrow D direction, which is the same direction as the arrow R direction of the rotary atomizing head 11, can be generated by being discharged to the front of the.

Reference numeral 14 denotes a shaping air ring according to the present embodiment. The shaping air ring 14 is located rearward of the paint discharge edge 11C of the rotary atomizing head 11 and covers the expanding portion 11A1 of the outer peripheral surface 11A. In this way, it is provided on the front end side of the coating machine main body 1. The shaping air ring 14 has a double outer ring portion 15,
The inner ring portion 16 and the respective ring portions 15 and 16
An annular gap serving as the air ejection port 17 is formed on the tip end side between them.

Shaping air is ejected from the air ejection port 17 toward a position facing the groove 13 on the outer peripheral surface 11A of the rotary atomizing head 11. Further, inside the shaping air ring 14, a chamber chamber 18 communicating with the air ejection port 17 is provided. Therefore, the air protruding port 17 is
The first outer peripheral surface 11A is open at a position on the rear side of the expanded portion 11A1 and at a position facing the concave-convex groove 13.

Reference numeral 19 indicates an air source provided outside the main body 1 of the coating machine.
It is connected via 8A. Further, by appropriately adjusting the amount of air supplied from the air source 19, the amount of air ejected from the air ejection port 17 is adjusted.

The rotary atomizing head type coating apparatus according to this embodiment is constructed in this way, and its operation will be described below.

First, as in the prior art, by applying a high voltage to the main body 1 of the coating machine, the rotary shaft 4 and the rotary atomizing head 1 are rotated.
1 is charged to a high voltage to form an electrostatic field with the object to be coated, and the rotary shaft 4 and the rotary atomizing head 11 are rotated at high speed by the air motor 3 in the main body 1 of the coater.

In this state, the paint is supplied to the rotary atomizing head 11, and the supplied paint is charged by the centrifugal force generated by the rotation of the rotary atomizing head 11 while being spread along the paint smooth surface 11B. After being discharged as a film or liquid-like charged paint from the paint discharge edge 11C, it is atomized by mechanical atomization or electrostatic atomization to become charged paint particles. At this time, since the rotary atomizing head 11 is rotating at a high speed, the centrifugal force causes the charged paint particles to fly outward from the paint discharge edge 11C in the radial direction.

Here, the shaping air ejected from the air ejection port 17 in the direction of the arrow C is the uneven groove formed in the expanding portion 11A1 of the outer peripheral surface 11A of the rotary atomizing head 11 rotating at high speed. Flowing along the line 13, the shaping air changes into a swirling flow in the direction of arrow D in front of the rotary atomizing head 11. Then, the charged paint particles discharged outward from the paint discharge edge 11C in the radial direction are sprayed forward by this swirling flow to form a thin film pattern having a larger diameter than the conventional paint spray pattern without increasing the amount of air. can do.

Further, in the coating apparatus according to the present embodiment, it is possible to form a paint spray pattern having a large diameter without increasing the air amount of the shaping air. Therefore, the air amount of the shaping air that has been conventionally generated is increased. By doing so, it is possible to reduce the air pumping phenomenon that has occurred, to prevent “flapping” due to the paint particles, and to reliably improve the coating efficiency.

On the other hand, the swirling flow in the direction of arrow D consists of the air pressure and the centrifugal force due to the movement in the rotational direction, and the rotary atomizing head 11
A suction force due to negative pressure is generated near the center of the shaft. However, since not only the air pressure but also the centrifugal force due to the swirling flow is applied to the charged paint particles, the charged paint particles flying toward the object to be coated can be applied without causing the air pumping phenomenon that is pulled by the suction force. The efficiency can be improved.

Further, the air amount of the shaping air ejected from the air ejection port 17 can be appropriately adjusted by the air source 19, so that if the air amount from the air source 19 is increased, the air is ejected from the air ejection port 17. The shaping air can be increased, the radial dimension of the swirling flow can be increased, and the paint spray pattern can be a large-diameter thin film. As a result, the coating work time can be greatly reduced and the finish quality of the coated surface can be improved.

Furthermore, the size of the paint spray pattern can be appropriately changed by adjusting the amount of air from the air source 19 according to the coating conditions.

However, in the rotary atomizing head type coating apparatus according to the present embodiment, the shaping air ejected from the shaping air ring 14 is used for the rotary atomizing head 13 by utilizing the large number of concave and convex grooves 13 formed in the rotary atomizing head 11. Since the swirl flow is generated in front of the chemical head 11, it is possible to form a large-diameter paint spray pattern even with a small amount of shaping air, reduce the air pumping phenomenon, and improve the coating efficiency. It can be significantly improved.

Further, the size of the paint spray pattern can be increased by the swirling flow as compared with the prior art, and the thickness of the coating film can be made uniform so that a wide pattern can be applied. Compared with this, the painting work time can be greatly reduced and the painted surface can be finished neatly.

Further, when a metallic paint is used as the paint, the particle speed of the paint particles when applied to the object to be coated becomes a problem, and when the particle speed is not appropriate, a glossy coating should be realized. However, by adjusting the shaping air from the air ejection port 17 like the shaping air ring 14 of the present embodiment, it is possible to adjust the swirling air amount and the centrifugal force, and it is glossy. The painted surface can be easily realized.

Incidentally, referring to FIGS.
An example will be shown and described.

First, FIG. 4 shows a second embodiment. As shown in FIG. 4, a large number of concave and convex grooves 22 as current transformers are formed on the entire circumference of the expanding portion 21A1 of the outer peripheral surface 21A of the rotary atomizing head 21. 22 are formed, and each of the concave and convex grooves 22 is inclined in the rotational direction with respect to the axial direction of the rotary atomizing head 21. In addition, 21
C is the paint discharge edge.

Next, FIG. 5 shows a third embodiment. In the outer peripheral surface 31A of the rotary atomizing head 31, a large number of vane plates 32 serving as current transformers are formed on the entire circumference of the expanding portion 31A1. 32 are formed, and the respective vane plates 32 are arranged parallel to the axial direction of the rotary atomizing head 31. In addition, 31C becomes a paint discharge edge.

Further, in the fourth embodiment shown in FIG. 6, each blade plate 32 according to the third embodiment is a blade plate 32 'which is inclined in the rotational direction with respect to the axial direction of the rotary atomizing head 31. Especially.

In each of the embodiments thus constructed, the same effects as those of the first embodiment described above can be obtained, but the uneven groove 22 according to the second embodiment or the blade according to the fourth embodiment is obtained. The concavo-convex shaped body composed of the plate 32 'is inclined with respect to the axial direction, so that the centrifugal force due to the swirling flow is
It can be made larger than that of the embodiment.

Further, in the second and fourth embodiments, a large number of concave and convex grooves 22 and vane plates 32 'in which the current transformer is inclined in the rotational direction with respect to the axial directions of the rotary atomizing heads 21, 31 are provided. However, a large number of uneven grooves or blades forming the current transformer may be formed by inclining in a direction opposite to the rotating direction of the rotary atomizing head.

[0051]

As described above in detail, according to the first aspect of the invention, the air jetting means is provided behind the rotary atomizing head and jets the shaping air radially inward of the paint discharge edge. Since the shaping current that changes the shaping air jetted from the air jetting means into a swirling flow in front of the rotary atomizing head is formed on the outer peripheral surface of the rotary atomizing head on the paint discharge edge side, Even if a small amount of shaping air is used, the paint spray pattern can be made large in diameter by the swirling flow, the coating film of the object to be coated can be made uniform, and the finished quality of the coated surface of the object to be coated can be improved. Further, by adjusting the air amount of the shaping air, the paint spray pattern can be made large in diameter when the air amount is large, and can be adjusted appropriately by making the pattern small in diameter when the air amount is small.

According to the second aspect of the present invention, the shaping is performed on the front end side of the coating machine main body so as to be located rearward of the paint discharge edge of the rotary atomizing head and cover the rear portion on the outer peripheral side of the rotary atomizing head. Since the air ring is provided and the air ejecting means is formed in the shaping air ring, the shaping air ejected from the air ejecting means can be applied to the outer peripheral surface of the rotary atomizing head, and the rotary atomization is performed by the current transformer. A swirling flow can be generated in front of the head. And the painted surface can be finished neatly.

According to the third aspect of the present invention, since the current-changing portion is formed by the concave-convex body formed of a large number of concave-convex grooves or blades formed over the entire outer peripheral surface of the rotary atomizing head, the shaping air is formed. Flowing along each concave and convex groove or each blade, the shaping air can be transformed into a swirling flow in front of the rotary atomizing head even when the shaping air is small, reducing the air pumping phenomenon and coating The coating film of the object can be made uniform, and the finish quality of the coated surface can be improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a coating machine body, a rotary shaft, a rotary atomizing head, and a shaping air ring according to a first embodiment of the present invention.

FIG. 2 is a side view showing a state in which the rotary atomizing head in FIG. 1 is viewed from the side.

FIG. 3 is a front view showing a rotary atomizing head together with the shape of a swirling flow.

FIG. 4 is a side view showing a rotary atomizing head according to a second embodiment.

FIG. 5 is a side view showing a rotary atomizing head according to a third embodiment.

FIG. 6 is a side view showing a rotary atomizing head according to a fourth embodiment.

FIG. 7 is an overall view of a rotary atomizing head type coating apparatus according to the prior art.

[Explanation of symbols]

 1 Coating Machine Main Body 3 Air Motor 4 Rotating Shafts 11, 21, 31 Rotating Atomizing Heads 11A, 21A, 31A Outer Surface 11B Paint Smooth Surface 11C, 21C, 31C Paint Discharge Edge 13,22 Concavo-convex Groove (Transforming Section) 14 Shaping Air ring 17 Air jet (air jetting means) 19 Air source 32, 32 'Vane plate (transformer)

Claims (3)

[Claims] 1. A main body of a coating machine having an air motor inside and a rotatably provided by an air motor on the tip side of the main body of the coating machine, the outer peripheral surface of which is cylindrical or cup-shaped and the inner peripheral surface of which is a smooth coating surface. A spray atomizing head, an air jetting means located behind the rotary atomizing head for jetting shaping air radially inward of the paint jetting edge, and the rotary atomizing head. A rotary mist formed on the outer peripheral surface of the paint discharge edge side and configured to transform the shaping air ejected from the air ejecting means into a swirl flow in front of the rotary atomizing head. Head type coating equipment. 2. A shaping air ring is provided on the tip side of the main body of the coating machine, the shaping air ring being located rearward of the paint discharge edge of the rotary atomizing head so as to cover the outer peripheral rear portion of the rotary atomizing head,
The rotary atomizing head type coating device according to claim 1, wherein the air jetting means is provided on the shaping air ring. 3. The rotary atomizing head mold according to claim 1, wherein the current changing portion is formed by an uneven body having a plurality of grooves or blades formed on the entire outer peripheral surface of the rotary atomizing head. Coating equipment.