JPH0824721A - Spray head of rotary spray coating apparatus - Google Patents

Abstract

PURPOSE:To prevent the deformation and destruction of solid coating material ingredients to perform good metallic coating by electrifying a coating material to form it into a thin film before inclining plural groove parts for dividing the thin film in liquid threads so that it may be directed backwards in the rotational direction outwards in the radial direction of a spray head. CONSTITUTION:When a coating material P is introduced into a coating material introducing hole 3 in a boss part 2 with a spray head A being electrified and rotated, the coating material P moves to a coating material accumulated chamber 10 between the inner and the outer flanges 4, 7 through a through-hole 5 of the inner flange 4. After the coating material P has moved along a taper face 6 of the inner flange 4, it passes through coating material discharge holes 8 of the outer flange 7 and is discharged to the inner surface of the tip of the spray head A. Further, after the coating material P in the form of a taperlike formed surface 12 moves outward in the radial direction and is formed into a thin film, it is divided in liquid threads by plural grove parts 14 and sprayed into fine particles. At this time, since the groove parts 14 are inclined so that they may be directed backward in the rotational direction outwards in the radial direction of the spray head A, the coating material P has a moving component backwards in the rotational direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an atomizing head provided in a rotary atomizing coating device.

[0002]

2. Description of the Related Art Conventionally, this type of rotary atomizing coating apparatus has been
It is widely used in the painting process of vehicles, etc., because it has a high coating efficiency and can obtain a beautiful coated surface by atomizing the coating. That is, this rotary atomizing coating device is provided with a substantially cup-shaped atomizing head that rotates at a predetermined speed, and a paint discharging portion that discharges the supplied paint is formed near the center of the inner surface of the atomizing head. In the vicinity of the outer circumference, a film forming surface is formed which is tapered outward in the radial direction toward the tip side in the axial direction of the atomizing head. Then, the paint discharged from the paint discharge unit is moved radially outward on the film-forming surface by the centrifugal force caused by the rotation of the atomizing head to form a film while being charged, and the thin film of the film-formed paint is atomized. It is made to atomize by ejecting it in the form of a liquid thread from the tip of the head.

As an example of this atomizing head, as disclosed in, for example, Japanese Patent Application Laid-Open No. 4-227082, a large number of fins are circumferentially arranged at a predetermined pitch on the inner surface of the tip of the atomizing head. A large number of grooves are formed so that the inner ends of the fins are continuous to the film-forming surface between the fins, and the thin film of the coating film formed on the film-forming surface is divided at each groove to form a liquid thread. It has been proposed that after molding, it is ejected from the tip of the atomizing head and atomized.

[0004]

By the way, a rotary atomizing coating apparatus using such an atomizing head can form a beautiful coating film as described above for solid coating, but aluminum pieces, mica pieces, etc. When performing metallic coating containing the solid coating component (1), there were the following problems. That is, in the metallic paint, when the solid paint component is deformed or destroyed by the shear stress when the solid paint component jumps out from the tip of the atomizing head together with the paint, the particle size becomes small, and The orientation becomes irregular and the color becomes dull, and a good metallic color cannot be obtained.

Therefore, for example, if the rotation speed of the atomizing head is slowed and the deterioration of the atomization of the coating material caused thereby is compensated by the blowout of assist air, the shear stress received by the solid coating material component is reduced. It is possible to suppress the deformation and breakage, and obtain a good metallic feeling.

In this case, however, the assisting air compensates for the insufficient atomization of the paint due to the reduction in the rotation speed of the atomizing head, so that the coating efficiency is much lower than that of this air, and the rotary atomizing coating apparatus has a high coating efficiency. It cannot be denied that the original excellent points are greatly impaired.

The present invention has been made in view of the above points, and an object of the present invention is to improve the shape of the groove portion in the atomizing head having the groove portion on the inner circumference of the above-mentioned tip portion to improve the rotary atomization. While maintaining the original high coating efficiency of the coating equipment, the shear stress applied to the solid coating components such as aluminum pieces is reduced to prevent its deformation and destruction, and good metallic coating can be performed using the rotary atomization coating equipment. To do so.

[0008]

In order to achieve the above object, in the present invention, the groove portion of the atomizing head is inclined toward the tip side of the atomizing head toward the rear side in the direction of rotation of the atomizing head, and the metallic paint The solid paint components such as aluminum pieces were guided by the groove so that they could be smoothly ejected from the tip of the atomizing head without receiving a large shear stress.

Specifically, according to the first aspect of the present invention, a substantially cup-shaped atomizing head is provided in the rotary atomizing coating device and is configured to rotate at a predetermined speed. ,
It has a film forming surface that is tapered outward in the radial direction toward the tip side in the axial direction, and a large number of grooves are formed in the film forming surface located on the inner surface of the tip portion at a predetermined pitch in the circumferential direction. After being formed, the coating material discharged from the coating material discharging section is moved to the outer side in the radial direction on the film-forming surface by a rotating centrifugal force to form a film on a thin film while being charged, and the thin film is divided into liquid threads at the groove part, It is premised on an atomized head that is made to atomize by popping out from the tip.

Further, each of the above groove portions is inclined toward the outer side (the tip side) in the radial direction of the atomizing head toward the rear side in the rotational direction.

According to the second aspect of the present invention, each groove has an inner end extending in the radial direction of the atomizing head, and the atomizing is performed from the inner end toward the radially outer side (tip side). It shall be curved smoothly toward the rear side of the head's direction of rotation.

According to the third aspect of the invention, the tip of the atomizing head has an arcuate cross section.

In the invention of claim 4, the paint atomized by the atomizing head is a metallic paint containing aluminum pieces, mica pieces and the like.

[0014]

With the above construction, in the invention of claim 1, when the atomizing head is rotating at a predetermined speed, when the paint is discharged from the paint discharging part on the inner surface of the atomizing head, the discharged paint is
It receives a centrifugal force due to the rotation of the atomizing head, moves radially outward on the tapered film forming surface of the inner surface of the atomizing head, and during this period, a thin film is formed while being charged. The coating material that has become a thin film is further moved outward by the centrifugal force to enter the groove portion, is divided into liquid threads in the groove portion, and then is ejected from the tip portion of the atomizing head to be atomized.

At this time, since each of the grooves is inclined outward in the radial direction of the atomizing head so as to be directed toward the rear side in the rotational direction, the thin film-like coating material is divided into the grooves and then, Guided by the groove, it moves to the rear side in the direction of rotation of the atomizing head. That is, the paint is guided in the groove portion and gradually and smoothly turns to the rear side in the rotation direction, and when it jumps out from the tip of the atomizing head, it jumps out with a moving component to the rear side in the rotation direction. Therefore, for example, even in the case of a metallic paint containing solid paint components such as aluminum pieces and mica pieces in the paint, the solid paint components are subjected to excessive shear stress when jumping out from the tip of the atomizing head. Therefore, it is possible to prevent deformation and destruction of the rotary atomization coating device, and thus to maintain high performance of the rotary atomization coating device and ensure high coating efficiency, and to perform metallic coating using the rotary atomization coating device. .

According to the second aspect of the invention, the inner end of each groove extends in the radial direction of the atomizing head and is in the same direction as the centrifugal force applied to the paint on the film-forming surface. The paint that has received the centrifugal force on the outside in the direction smoothly enters the inner end of the groove. Since each groove is curved so as to go to the rear side in the rotation direction of the atomizing head from the inner end toward the outer side in the radial direction, the paint that has entered the inner end of the groove is guided to the groove. As a result, the atomizing head turns smoothly to the rear side. Therefore, the turning of the paint to the rear side in the rotation direction becomes smoother, and the shearing stress received by the solid paint component in the paint when it jumps out is further reduced by that amount, and its deformation and destruction are effectively prevented. You can

According to the third aspect of the present invention, since the tip of the atomizing head has an arcuate cross section, the paint is smoothed out when it comes out of the groove and jumps out of the tip of the atomizing head. It is possible to reduce the shear stress applied to the paint components, and to more effectively prevent the deformation and breakage of the paint components.

In the invention of claim 4, since the paint is a metallic paint containing aluminum pieces, mica pieces, etc., when the metallic paint jumps out from the tip of the atomizing head, deformation of the aluminum pieces, mica pieces, etc. It is possible to suppress breakage, etc., and metallic coating can be performed using a rotary atomizing coating device.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. 4 and 5 show an atomizing head A according to an embodiment of the present invention. The atomizing head A is provided in a rotary atomizing coating device that electrostatically paints a paint, and is driven by a drive motor (not shown). It is driven to rotate about the axis C at a predetermined speed in the counterclockwise direction in FIG. 4, for example. Further, the atomizing head A is charged to a predetermined electric potential (for example, -90 kV), the paint is charged with this electric potential to be released in an atomized state, and this charged paint is applied to an object such as a vehicle body of the vehicle by electrostatic attraction. It is designed to fly and adhere to paint.

The atomizing head A has a substantially cup-like shape opened toward the tip side (downward in FIG. 5), and the diameter of the opening of the atomizing head A is, for example, 50 mm. Further, as shown in enlarged detail in FIG. 3, the tip portion 1 (opening edge portion) of the atomizing head A has an arcuate cross section.

The atomizing head A has a boss portion 2 at the center thereof,
A paint introducing hole 3 is formed through the boss portion 2.
Inside the atomizing head A, an inner flange portion 4 is fitted on the inner back side and an outer flange portion 7 is fitted on the tip end side (opening side) so as to close the opening of the atomizing head A, and are integrally fixed. A paint reservoir chamber 10 is formed between the flange portions 4 and 7. A communication hole 5 is formed at the center of the inner flange portion 4, and the paint P supplied to the paint introducing hole 3 of the boss portion 2 passes through the communication hole 5 and the paint reservoir chamber between the inner and outer flange portions 4 and 7. Sent to 10. The outer peripheral portion of the surface on the tip side of the atomizing head (lower surface in FIG. 5) of the inner flange portion 4 is a tapered surface 6 that is inclined so that the diameter increases toward the tip side of the atomizing head A. The paint P in the paint reservoir 10 is sent to the tip side of the atomizing head A along the tapered surface 6 by the centrifugal force generated as the head A rotates.

On the other hand, on the outer peripheral portion of the outer flange portion 7, there are provided a plurality of paint discharge holes 8, 8 for discharging the paint P in the paint reservoir chamber 10 to the surface of the outer flange portion 7 on the tip side of the atomizing head. It is formed so as to penetrate through it at a predetermined interval in the circumferential direction. In each of the paint discharge holes 8, the hole wall surface located radially outside of the outer flange portion 7 is located on the extension surface of the tapered surface 6 of the inner flange portion 4, and the hole center has the same inclination angle as the tapered surface 6. , So that the paint P flowing through the tapered surface 6 can be smoothly introduced into the paint discharge holes 8, 8, ... And discharged onto the inner surface of the atomizing head A of the outer flange portion 7 on the tip side. ing.

Different from the outer periphery of each paint discharge hole 8 on the surface of the outer flange portion 7 on the tip side of the atomizing head to the tip of the atomizing head A, the diameter increases toward the tip side of the atomizing head A. Film-forming surface 1 that is tapered in two steps at an inclination angle
2 is formed, and the paint P discharged from the paint discharge holes 8, 8, ... Is moved toward the tip side of the atomizing head A along the film formation surface 12 by the centrifugal force generated by the rotation of the atomizing head A. It is moved toward the outer side in the radial direction, and while it is being charged, a thin film is formed.

Further, a large number of grooves 14, 14, ... Are formed at a predetermined pitch in the circumferential direction on the film forming surface 12 located on the inner surface of the tip of the atomizing head A. 1
The thin film of the coating material P formed in 2 is divided into liquid threads by the groove portions 14, 14, .... Then, the liquid thread-shaped coating material P is ejected from the tip portion 1 of the atomizing head A in a liquid thread shape, and the tip ends are atomized into fine particles.

The feature of the present invention resides in the shape of each groove 14. That is, as shown in FIG. 4, each groove 14 is inclined toward the outer side (tip side) in the radial direction of the atomizing head A toward the rear side in the rotation direction. More specifically, as shown in enlarged detail in FIG. 1, each groove 14 has an inner end 14a extending in the radial direction of the atomizing head A, and the inner end 14a
The curved portion is smoothly curved so as to be directed toward the rear side in the rotation direction of the atomizing head A from the outside in the radial direction.

As shown in the enlarged view of FIG. 2, each groove 14 has a V-shaped cross section, and its depth d is, for example, d = 0.3 m.
and the pitch p of the groove portions 14, 14, ... Is p = 0.2.
mm.

Therefore, in the above-mentioned embodiment, when electrostatically painting the vehicle body or the like as the object to be coated in the coating booth, the atomizing head A is charged to a potential of, for example, -90 kV, and the object to be coated is, for example, 0 V. As a result, the atomizing head A is rotated at a constant speed by a motor, and in this rotating state, the paint P is supplied to the paint introducing hole 3 in the boss portion 2 of the atomizing head A. The supplied paint P is sent to the paint reservoir chamber 10 between the inner and outer flange portions 4 and 7 through the communication hole 5 of the inner flange portion 4. The paint P in the paint reservoir 10 is sent to the tip side of the atomizing head A along the tapered surface 6 of the inner flange portion 4 by the centrifugal force generated by the rotation of the atomizing head A, and then the outer flange. Part 7
It is discharged onto the inner surface of the tip of the atomizing head A through a plurality of paint discharge holes 8, 8, ...

The discharged paint P moves radially outward on the tapered film-forming surface 12 on the inner surface of the atomizing head A under the centrifugal force generated by the rotation of the atomizing head A, and is charged during this time. While being processed, a thin film is formed. This thin film paint P
Move further outward by the centrifugal force and enter the groove portions 14, 14, ... On the inner surface of the tip of the atomizing head A as shown in FIG. 2, and are divided into liquid threads by these groove portions 14, 14 ,. After these liquid thread-shaped paints P have come out from the grooves 14, 14 ,.
The liquid thread is ejected from the tip portion 1 of the atomizing head A into the coating booth and atomized into particles in order from the tip. Since the atomized fine particles of the coating material P are charged, they fly toward the object to be coated due to electrostatic attraction, and adhere to it to form a coating film.

In this case, each groove 14 at the tip of the atomizing head A is
Since the inner end portion 14a of the coating material extends in the radial direction of the atomizing head A and is in the same direction as the centrifugal force that the coating material P receives on the film forming surface 12, the coating material P that receives this centrifugal force on the film forming surface 12 is The groove 14 smoothly enters the inner end 14a and is divided.
And each groove part 14 inclines toward the radial direction outer side (tip side) of the atomization head A so that it may go toward a rotation direction back side, that is, the atomization head from the said inner end part 14a toward a radial direction outer side. Since it is curved so as to be directed to the rear side in the rotation direction of A, the paint P that has entered the inner end portion 14a of the groove portion 14 is
When it is guided in the groove portion 14 and smoothly turns to the rear side in the rotation direction of the atomizing head A, and thereafter, when the liquid thread-shaped paint P jumps out from the tip portion 1 of the atomizing head A, it moves to the rear side in the rotating direction. It will have ingredients. For this reason, even if the paint P contains a solid paint component such as an aluminum piece or a mica piece, the solid paint component causes an excessive shearing stress when jumping out from the tip 1 of the atomizing head A. Is hardly received, and its deformation and destruction are reduced. Moreover, as shown in FIG. 3, since the tip end portion 1 of the atomizing head A has an arcuate cross section, the liquid thread-like paint P comes out from the groove portion 14 and is atomized head A.
The movement of the tip end portion 1 when it is projected outward in the radial direction is also smooth, and the shear stress on the solid paint component can be further reduced to effectively reduce its deformation and breakage. As a result, even a metallic paint having a solid paint component such as an aluminum piece that is easily deformed or destroyed does not cause a problem such as its deformation. Therefore, it is possible to perform metallic coating using a rotary atomization coating device. A metallic feel is obtained.

Further, since there is no deformation of the solid paint component, the rotation speed of the atomizing head A can be set to a high value as usual to improve and maintain the atomization of the paint P. It is possible to maintain good performance of the device and ensure high painting efficiency.

In addition, although the above-mentioned embodiment is a case where metallic paint is applied, it goes without saying that the atomizing head A can also be used for solid paint.

FIG. 6 shows the average particle size of aluminum pieces in the paint when the peripheral speed of the atomizing head A is changed when the metallic paint is applied by rotating the atomizing head A as in the above-mentioned embodiment. It is a result diagram of the experiment. According to FIG. 6, in the conventional example shown by a broken line in the figure (where the groove portion is not inclined rearward in the rotation direction), when the peripheral speed of the atomizing head is increased, the aluminum piece is deformed or destroyed. In contrast to the smaller particle size, in the present invention, there is no such deformation and the like, and the particle size of the aluminum piece can be maintained at a desired large particle size, and thus the present invention provides a good metallic coating film. It can be seen that

[0033]

As described above, according to the first aspect of the present invention, in the substantially cup-shaped atomizing head which is provided in the rotary atomizing coating device and rotates at a predetermined speed, it is located on the inner surface of the tip portion. By coating each of a large number of grooves formed on the film surface at a predetermined pitch in the circumferential direction toward the outer side in the radial direction of the atomizing head toward the rear side in the rotational direction, In the groove, gradually turn to the rear side in the direction of rotation,
Since it can be ejected with a moving component to the rear side in the rotation direction from the tip of the atomizing head, the solid paint components such as aluminum pieces and mica pieces contained in the paint will not fly from the tip of the atomizing head. It is possible to prevent excessive shear stress at the time of taking out and prevent its deformation and destruction. Therefore, it is possible to perform metallic coating while using the rotary atomization coating device while ensuring high coating efficiency.

According to the second aspect of the present invention, the inner end portion of each groove portion extends in the radial direction, and the groove portion is directed toward the rear side in the rotational direction of the atomizing head as it extends radially outward from the inner end portion. By smoothly bending it, the inner end of each groove has the same atomizing head radius direction as the centrifugal force that the paint receives on the film-forming surface,
The paint that has been subjected to centrifugal force on this film formation surface can be smoothly introduced to the inner end of the groove, and then the paint that has entered the inner end of the groove can be smoothly redirected to the rear side in the direction of atomization head rotation. It is possible to more smoothly perform the turning to the rear side in the rotating direction, effectively prevent the deformation and destruction of the solid paint component in the paint when the paint is ejected, and perform the metallic coating more favorably.

According to the invention of claim 3, the tip of the atomizing head has an arc-shaped cross section, so that the movement of the paint when it comes out of the groove and jumps out of the tip of the atomizing head is smoothed, and the solid paint component is removed. It is possible to reduce the shearing stress, effectively prevent its deformation and breakage, and further improve the quality of the coating.

According to the fourth aspect of the present invention, the paint is a metallic paint containing aluminum pieces, mica pieces, etc., so that the aluminum pieces, mica pieces, etc. are deformed when the metallic paint jumps out from the tip of the atomizing head. It is possible to suppress damage and the like, and it is possible to perform metallic coating while using the rotary atomizing coating device.

[Brief description of drawings]

FIG. 1 is an enlarged view of a part of a groove portion of an atomizing head according to an embodiment of the present invention as viewed from the inner surface side.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an enlarged sectional view of the atomizing head tip portion.

FIG. 4 is a plan view of the atomizing head.

FIG. 5 is a sectional view taken along the axis of the atomizing head.

FIG. 6 is an experimental result diagram illustrating an average particle size of aluminum pieces of metallic paint with respect to a change in peripheral velocity of an atomizing head.

[Explanation of symbols]

 A atomization head 1 tip part 8 paint discharge hole (paint discharge part) 12 film forming surface 14 groove part 14a inner end p groove pitch C shaft center P paint

Claims (4)

[Claims] 1. A rotary atomizing coating device is provided so as to rotate at a predetermined speed, and has a paint discharge portion on an inner surface and a taper shape that is radially outward toward a tip end side in an axial direction. Along with the film-forming surface, a number of grooves are formed at a predetermined pitch in the circumferential direction on the film-forming surface located on the inner surface of the tip part, and the paint discharged from the paint discharge part is formed by rotational centrifugal force. A substantially cup-shaped atomizing head that moves radially outward on the surface to form a thin film while charging, divides the thin film into liquid threads at the groove, and then ejects from the tip to atomize. In the atomization head of the rotary atomization coating device, each of the grooves is inclined so as to be directed toward the outer side in the radial direction of the atomization head toward the rear side in the rotation direction. 2. The atomizing head of the rotary atomizing coating apparatus according to claim 1, wherein each groove portion has an inner end portion extending in the radial direction of the atomizing head, and is radially outward from the inner end portion. The atomizing head of the rotary atomizing coating device is characterized by smoothly curving toward the rear side in the rotation direction of the atomizing head as it goes to. 3. The atomizing head of the rotary atomizing coating device according to claim 1, wherein the tip portion has an arcuate cross section. 4. The atomizing head of the rotary atomizing coating apparatus according to claim 1, wherein the coating material is a metallic coating material containing aluminum pieces, mica pieces and the like. Atomized head.