JP3473718B2 - Rotary atomization electrostatic coating method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary atomizing electrostatic coating method and apparatus used for coating vehicle bodies and the like.

[0002]

2. Description of the Related Art Recently, for painting a vehicle body, paint is supplied to the inner peripheral surface of a rotating cup-shaped atomizing head, which is atomized by centrifugal force, and is atomized from the peripheral edge of the tip of the atomizing head. A rotary atomization electrostatic coating method is widely used, in which the coating material is discharged and the coating material is sprayed to the surface of the coating object by a high voltage applied between the coating object and the cup-shaped atomizing head.

Such a rotary atomizing electrostatic coating method generally has a higher paint adhesion efficiency than air atomizing electrostatic coating or airless atomizing coating.

However, in the above-mentioned rotary atomizing electrostatic coating method, when the rotation speed of the cup-shaped atomizing head (hereinafter referred to as a cup) is very fast, the paint is applied to the cup by centrifugal force. May be scattered in the radial direction,
To prevent this, concentrically with the cup, shaping air is discharged from the cup side to the side of the object to be coated to form an air layer, which regulates the scattering direction of the paint. There is an electrostatic coating device.

An example of such a rotary atomizing electrostatic coating device is disclosed in Japanese Patent Application Laid-Open No. 58-92475, which is supplied to a coating machine G as shown in FIGS. 24 and 25. The coating material passes through the coating material flow path 118 formed in the holder 116 and the rotating electrode nozzle 119.
Flow into the first chamber 122. At this time, since the DC high voltage is applied to the rotary electrode nozzle 119 and the air motor 115 rotates at high speed, the coating material passes through the communication holes 124 of the straightening vane 121 and the second chamber 123.
After being introduced into the inside, it is spread by centrifugal force, is thinned along the inner wall surface of the second chamber 123 toward the outside opening side of the air nozzle 125, and is injected from the outlet 133 in a state of being charged to the negative electrode. .

On the other hand, the introduction pipe 129 pressure-fed to the coating machine G
After that, the air is passed through the air chamber 128 in the atomizing head G2.
Flow into the injection chamber 125D through the groove 126 of the air nozzle 125. Then, the air enters the groove 125.
Each spiral groove 1 provided in the groove portion 125B when passing through B
Since the swirling force is applied to the air by 26 to 126, the air jetted from the jetting chamber 125D becomes a spiral flow, and as a result, the sprayed trace on the object to be coated becomes a coating pattern while drawing an arc. Therefore,
Shielding plate 1 with uniform coating without uneven coating
By 31 the paint in the second chamber 123 is blocked from contact with the jet flow of air that is a spiral flow, and the thin film spread state is protected, so the atomization state of the paint becomes good, and as a result, It is possible to obtain a good quality painted surface.

26 to 29 are disclosed in Japanese Patent Laid-Open No. 3-101858, and a main body 51 is provided with a rotary shaft 52 driven by a motor (not shown). Then, the cup 53 is fixed to the tip of the rotary shaft 52 extending to the outside of the main body 51, and the head member 54 fixed to the tip of the main body 51 has a hole 53 into the cup 53.
Paint supply pipe 55 and cup 5 for supplying paint from a
3, a blower outlet 56 for supplying shaping air toward the back surface of the outer peripheral edge portion of No. 3 is provided.

The outlets 56 for discharging the shaping air are arranged on a pitch circle slightly larger than the diameter of the cup 53, and the outlets 56 are arranged so that the discharge direction of the outlets 56 is within the plane including the tangent line of the cup 53. Inclined by a predetermined angle (twist angle) β with respect to the axis (FIG. 28), and
The twisting direction is rearward with respect to the rotation direction P of the cup 53 (FIG. 27). With such a configuration, the shaping air discharged from the outlet 56 flows in a spiral locus as shown in FIG. 29, and a centrifugal force acts on it, resulting in The shaping air overcomes the suction force due to the negative pressure generated in the front region of the cup 53 and flows so as to spread slightly on the downstream side, and the pattern does not shrink. In other words, because the coating pattern does not shrink, uneven coating is less likely to occur,
The quality of the painted surface can be improved.

[0009]

However, in general, the role of shaping air is to accelerate the atomization of the paint as well as to form the pattern. From this point, the flow velocity of the air toward the outer peripheral edge of the cup 53 is Faster is better, but in the above rotary atomizing electrostatic coating device, as the flow rate of air increases, the amount of air discharged increases, so the paint scatters without adhering to the object to be coated, and the coating efficiency is improved. However, there is a problem that

On the contrary, in order to improve the coating efficiency, the shaping air speed may be slowed down. However, if the shaping air speed is too slowed for the above reason, the atomization of the paint is not promoted, Irregularities are likely to occur on the painted surface, resulting in poor finish quality.

Further, the shaping air toward the outer peripheral edge of the cup 53 is blown out from a large number of circular air outlets 56, but as shown in FIG. 6, it is blown out from the circular air outlets 56 adjacent to each other. Since the shaping air diffuses and interferes with each other at the outer peripheral edge of the cup, unevenness in the flow velocity of the shaping air occurs partially, so that there is a problem that the paint is not uniformly atomized.

Furthermore, in order to increase the diameter of the coating pattern, it is necessary to increase the twist angle of the air. However, if the twist angle is too large, the coating pattern becomes a donut shape and it becomes difficult for the paint to adhere to the center. , Easy to cause uneven coating.

On the other hand, according to the above rotary atomizing electrostatic coating device, the coating pattern is circular, but when the circular coating pattern is out of the object to be coated, or the desired coating pattern. When it is desired to mold, it is necessary to obtain a specific coating pattern shape.
As a rotary atomizing electrostatic coating device for obtaining a specific coating pattern shape, for example, Japanese Patent Application Laid-Open No. 57-1804.
There is one disclosed in Japanese Patent Laid-Open No. 60.

This is as shown in FIG.
8 is applied, an air flow 60 that distorts the air layer 59 inward is jetted from an air nozzle 57 from the outside of the air layer 59 formed by shaping air.

In such a rotary atomizing electrostatic coating device, it is possible to change the coating pattern shape,
There is a problem that the thickness of the coating applied to the object to be coated cannot be made uniform, and even if the air nozzle 57 that distorts the shaping air from the outside is arranged in the peripheral portion of the cup 53, this air will not rotate. The pressure in the vicinity of the center of the cup 53 is reduced by advancing in a direction parallel to, and therefore the paint tends to concentrate in the center direction, and there is a problem that the diameter of the coating pattern cannot be increased. The problem was to solve the problem.

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and has a wide range of adjustment of a coating pattern and a rotary atomizing electrostatic coating method that enables coating with excellent finish quality. And to provide a device.

[0017]

According to a first aspect of the present invention, there is provided a rotary atomizing electrostatic coating method, in which a cup-shaped atomizing head is fixed to the tip of a rotary shaft, and paint is applied to the inner peripheral surface of the atomizing head. In the rotary atomizing electrostatic coating method, in which the atomized head is supplied and atomized by centrifugal force, and the atomized paint is discharged from the peripheral edge of the tip of the atomizing head, coating in the air outlet row for coating pattern formation The sum of the diameter of the pattern forming air outlet and the coating pattern forming air outlet area is made larger than the sum of the atomizing air outlet diameter and the atomizing air outlet area in the atomizing air outlet row. And, while blowing out the atomizing air from a plurality of positions from the outer periphery behind the tip of the atomizing head toward the peripheral portion of the atomizing head, of the plurality of positions behind the tip of the atomizing head. Paint from multiple positions on the outer circumference toward the front of the atomizing head A structure for blowing air for turn molding, rotary atomizing electrostatic coating method according to claim 2 of the present invention,
When the coating pattern forming air is blown out, the blowing direction thereof is twisted with respect to the rotation axis, and the rotary atomizing electrostatic coating method according to claim 3 of the present invention blows the atomizing air. At the time of taking out, the blowing direction is set to be a twisting direction with respect to the rotation axis.

Further, in the rotary atomizing electrostatic coating device according to the fourth aspect of the present invention, the paint supplied to the inner peripheral surface of the cup-shaped atomizing head fixed to the tip of the rotary shaft is atomized by centrifugal force. In the rotary atomizing electrostatic coating device that atomizes and sprays atomized paint from the peripheral edge of the atomizing head, the diameter of the air outlets and the diameter of the air outlets for forming the coating pattern in the row of air outlets for forming the coating pattern The sum of the air outlet areas is formed larger than the sum of the diameters of the atomizing air outlets and the atomizing air outlet areas in the row of atomizing air outlets, and at the rear of the tip of the atomizing head. A row of atomizing air outlets consisting of a plurality of atomizing air outlets that blow air toward the peripheral edge of the atomizing head, and on the outer periphery of this atomizing air outlet further in front of the atomizing head. Air blowing for multiple coating pattern formation In the rotary atomizing electrostatic coating apparatus according to claim 5 of the present invention, the coating pattern forming air outlet row is formed by arranging a coating pattern forming air outlet row. 2 or more rows are arranged on the outer periphery of the air blower, and the sum of the diameters of the air outlets and the area of the air outlets in each air outlet row is increased in order from the atomizing air air outlet row to the outer coating pattern forming air air outlet row. And the rotary atomizing electrostatic coating device according to claim 6 of the present invention,
The rotary spraying electrostatic coating device according to claim 7 of the present invention has a structure in which the air outlet for forming the coating pattern is arranged such that its blowing direction is twisted with respect to the rotating shaft.
The atomizing air outlet is arranged such that the blowing direction thereof is twisted with respect to the rotation axis, and the rotary atomizing electrostatic coating device according to claim 8 of the present invention is the atomizing air outlet. The blowout port is arranged such that its blowout direction is opposite to the rotation direction of the atomizing head, and the rotary atomizing electrostatic coating device according to claim 9 of the present invention is provided with an atomizing air blowout port. Is formed as a narrow slit-like narrow gap in the circumferential direction, and the rotary atomization electrostatic coating device according to claim 10 of the present invention is configured such that the width of the slit-like narrow gap is 5 μm to 200 μm. The rotary atomizing electrostatic coating device according to claim 11 of the present invention has a structure in which the direction of the flow path communicating with the atomizing air outlet is twisted with respect to the rotation axis. The rotary atomizing electrostatic coating device according to claim 12 includes an atomizing air outlet and an atomizing air outlet. The rotary atomization electrostatic coating device according to claim 13 of the present invention has a structure in which an annular gap is formed in the inner periphery of the flow path communicating with it. In the rotary atomizing electrostatic coating device according to claim 14 of the present invention, the twisting direction of the atomizing air is the same as the twisting direction of the coating pattern forming air. According to a fifteenth aspect of the present invention, in the rotary atomizing electrostatic coating device of the present invention, the twist angle of the coating pattern forming air outlet is made larger than the twist angle of the atomizing air outlet. According to a sixteenth aspect of the present invention, in the rotary atomizing electrostatic coating device, the atomizing air outlet row and / or the coating pattern forming air outlet row has a shape of an ellipse or a polygon. The rotary atomizing electrostatic coating device according to No. 17 is used for atomizing It has a structure of changing the whole or a part of the twist angle of the outlets in the outlet rows and / or coating pattern shaping air outlet rows, and a means for solving the problems of the above configuration.

[0019]

The rotary atomizing electrostatic coating method according to claim 1 of the present invention and the rotary atomizing electrostatic coating apparatus according to claim 4 are:
With the above configuration, the functions of the atomizing air and the coating pattern forming air are separated, and the atomization of the paint by the atomizing air is promoted.
Independently of this, the coating pattern is formed by the air for forming the coating pattern. At this time, as the diameter of the coating pattern forming air outlets in the coating pattern forming air outlet row and the total sum of the coating pattern forming air outlet areas increase, the air flow velocity in the vicinity of the coating surface increases relatively, The speed of the paint particles that collide with the paint surface increases, and as a result, when metallic paint is used as the paint, the glitter material in the paint tends to spread horizontally with respect to the paint surface, increasing the tint of the paint. In addition, as the diameter of the atomizing air outlets in the atomizing air outlet row and the total sum of the atomizing air outlet areas are smaller, the flow velocity of air at the peripheral portion of the atomizing head increases relatively, The atomization of the paint is promoted in the peripheral portion of the atomizing head, and the sharpness of the painted surface, which has a strong correlation with the size of the paint particles, is further improved.

[0020]

In the rotary atomizing electrostatic coating method according to the second aspect of the present invention and the rotary atomizing electrostatic coating apparatus according to the sixth aspect, when the coating pattern forming air is blown out, its blowing direction is set to the rotation axis. In contrast, the twisting direction causes a certain amount of negative pressure to be generated inside the air layer formed by the coating pattern forming air, and acts so that the paint particles do not scatter to the outside of the air layer. ,Also,
Since the center of this negative pressure exists at a certain distance in front of the cup, the paint does not adhere to the inner surface of the cup.

The rotary atomizing electrostatic coating method according to the third aspect of the present invention and the rotary atomizing electrostatic coating apparatus according to the seventh aspect of the present invention are configured as described above, so that the direction of twist of the atomizing air outlet is By adjusting the / and the twist angle, the pressure in front of the cup is adjusted, and as a result, the size of the coating pattern is adjusted.

[0023]

In the rotary atomizing electrostatic coating apparatus according to the fifth aspect of the present invention, two or more rows of coating pattern forming air outlets are arranged on the outer periphery of the atomizing air outlet, and the atomizing air is provided. By increasing the sum of the diameters of the outlets and the area of the outlets in each outlet row in order from the outlet row to the outer coating pattern forming air outlet row, the air spread becomes larger toward the outside. Therefore, the paint is applied to the painted surface more uniformly and widely.

In the rotary atomizing electrostatic coating device according to the eighth aspect of the present invention, the atomizing air outlet has a blowing direction which is twisted with respect to the rotation axis and opposite to the direction of rotation of the atomizing head. By arranging so that when the air blowing direction is twisted in the direction opposite to the rotation direction of the atomizing head, the air that acts when the paint is scattered from the peripheral edge of the tip of the atomizing head The shearing force becomes larger than that when the air blowing direction is twisted in the same direction as the rotation direction of the atomizing head, and as a result, the paint is atomized with a smaller air flow velocity and flow rate.

According to a ninth aspect of the present invention, in the rotary atomizing electrostatic coating device, the atomizing air outlet is configured to have a narrow slit-like narrow gap in the circumferential direction. Although the flow velocity of will increase, the flow rate itself will decrease,
The atomization of the paint is further promoted, and the atomized paint is not scattered, and the width of the slit-like narrow gap at this time is 5 μm to 200 μm. Optimal.

The rotary atomizing electrostatic coating device according to the eleventh aspect of the present invention has the same operation as the rotary atomizing electrostatic coating device according to the seventh aspect by having the above configuration. The rotary atomizing electrostatic coating device according to claim 12 of the present invention has a configuration in which an annular gap is formed in the inner periphery of the atomizing air outlet and the flow path communicating with the atomizing air outlet. The air from the air outlets forms a very thin annular air layer, and advances toward the peripheral edge of the cup with the outer periphery of the air layer twisted with respect to the rotation axis, so each atomizing air outlet The air from the two does not interfere with each other and does not diffuse.

In the rotary atomizing electrostatic coating device according to the thirteenth aspect of the present invention, the atomizing air is twisted in the opposite direction to the coating pattern forming air. The relative velocity between the atomizing air and the coating pattern forming air increases, and as a result, the negative pressure in the space sandwiched between the atomizing air and the coating pattern forming air increases, and this negative pressure increases. Since the suction force is exerted by the pressure, scattering of paint particles is prevented.

According to a fourteenth aspect of the present invention, in the rotary atomizing electrostatic coating device, the twisting direction of the atomizing air and the twisting direction of the coating pattern forming air are in the same direction. Since the negative pressure of is relatively small, a larger coating pattern is formed.

In the rotary atomizing electrostatic coating apparatus according to the fifteenth aspect of the present invention, the twist angle of the coating pattern forming air outlet is made larger than the twist angle of the atomizing air outlet. The flow velocity of the air on the outside relatively increases, and the paint particles near the coating surface are attracted to the outside where the flow velocity is fast.
The paint will be evenly and widely applied to the painted surface.

According to a sixteenth aspect of the present invention, there is provided a rotary atomizing electrostatic coating device in which the atomizing air outlet row and / or the coating pattern forming air outlet row is oval or polygonal in shape. As a result, a coating pattern having a desired shape is formed on the coated surface.

With the rotary atomizing electrostatic coating device according to the seventeenth aspect of the present invention having the above-mentioned configuration, all or one of the twist angles of the atomizing air outlet and / or the coating pattern forming air outlet is formed. By appropriately changing the parts, the projected shape of the air on the surface to be coated can be elliptical or polygonal, so that a coating pattern having a desired shape can be obtained.

[0033]

[0034]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing a reference example of a rotary atomizing electrostatic coating apparatus according to the present invention. In FIG. 1, a cup 3 is fixed to a rotary shaft 4 of an air motor 1 and a motor housing. Reference numeral 2 fixes the air motor 1 and is connected to the head member 12.

The atomizing air supplied from the air flow path 11 passes through the pulsation absorbing chamber 10 and reaches the atomizing air outlet 6 formed between the head member 12 and the head member inner diameter portion 18. . This atomizing air outlet 6 is formed from a narrow slit-like narrow gap in the circumferential direction, and a plurality of atomizing air outlets 6 are arranged on the circumference around the rotation axis 4 of the cup 3. To form an atomizing air outlet row (not shown). Then, the atomizing air is blown from each of the atomizing air outlets 6 toward the peripheral portion of the cup 3.

Further, the air supplied from the coating pattern forming air supply pipe 8 passes through the pulsation absorbing chamber 9 and is blown from the coating pattern forming air outlet 7 toward the outer front side of the peripheral edge portion of the cup 3. It As with the atomizing air outlet 6, a plurality of coating pattern forming air outlets 7 are arranged on the circumference around the rotation axis 4 of the cup 3 to form the coating pattern forming air outlet row. I am configuring.

The paint supplied from the paint supply pipe 5 to the inside of the cup 3 rotating at a high speed passes through the hole 3a and the inner peripheral surface of the cup 3 to reach the peripheral portion on the opening side of the cup. It is atomized by the centrifugal force generated by the rotation of the cup 3 and the action of the air from the atomizing air outlet 6.

As described above, a plurality of narrow slit-shaped gaps are formed in the circumferential direction of the atomizing air outlet 6, and the width thereof is 5 μm to 200 μm. Therefore, since the area of the atomizing air outlet 6 is small, the flow velocity of the blown air is high and the atomization of the paint is promoted. However, since the flow rate of the blown air is small, the atomized paint is It does not scatter.

Therefore, no negative pressure is generated near the center in front of the cup, the paint particles are not concentrated near the center of the cup and the coating pattern is not reduced, and the paint adheres to the center of the front surface of the cup. And it does not cause so-called spitz.

FIG. 6 is an explanatory diagram showing the flow of air in the vicinity of the peripheral portion of the cup when the conventional air outlet 56 has a circular shape. The air blown out from each air outlet 56 spreads out and flows mutually. Interfere with each other, resulting in uneven air flow.

On the other hand, in the present invention, the atomizing air outlet 6 has a slit-like narrow gap, so that a very thin annular air layer 20 as shown in FIG. It is supposed to be blown out to.

Next, the atomized paint particles are directed toward the object to be coated in front of the cup by the air blown from the air outlet 7 for forming the coating pattern. As shown in FIGS. 2A and 2B, the coating pattern forming air outlet 7 blows air toward the front of the outer periphery of the cup 3 in a twisting direction with respect to the rotation axis of the cup 3. At this time, the coating pattern forming air blown out in the twisting direction forms a thin air layer, and a certain amount of negative pressure is generated inside this air layer. It is possible to prevent scattering to the outside of the layer.

2 (a) and 2 (b) are views showing the blowing directions of air from the atomizing air outlet 6 and the coating pattern forming air outlet 7 in the reference example of FIG. There, arrow P is the direction of rotation of cup 3, arrow 13
2 shows the blowing direction of the coating pattern forming air, and arrow 14 shows the blowing direction of the atomizing air.
In (a), the atomizing air is blown out in the direction perpendicular to the paper surface.

FIG. 3 is an explanatory view showing another reference example of the apparatus according to the present invention, in which the ring-shaped member 15 is provided inside the atomizing air outlet 6, that is, inside the pulsation absorbing chamber 10. As shown in FIGS. 4 and 8, the inner periphery of the ring-shaped member 15 is formed with a plurality of grooves 19 obliquely with respect to the central axis of the ring-shaped member 15.
Each of these corresponds to a slit-shaped narrow gap of the atomizing air outlet 6.

For this reason, when the air is blown out from the atomizing air blowout port 6 having a narrow slit-like shape, the air advances in a direction twisting with respect to the cup center axis,
Moreover, it becomes a slit shape and goes toward the peripheral portion of the cup 3.

FIG. 5 is a view showing the blowing directions of the coating pattern forming air and the atomizing air at this time.
(A) is the figure which looked at the front-end | tip part of a rotary atomizing electrostatic coating apparatus from the front, and FIG.5 (b) is the figure which was seen from the side.

In this reference example, the pattern forming air outlet 7 and the atomizing air outlet 6 are twisted in opposite directions. By doing so, the pattern forming air and the atomizing air are twisted. The relative velocity with the air increases, and the suction force due to the negative pressure near the center of the cup increases to some extent,
The scattering of paint particles can be suppressed.

10 to 14 are other reference examples in which the twisting directions of the coating pattern forming air and the atomizing air are changed.

First, in FIG. 10A, the diameter of the atomizing air outlet 6 is made larger than the outer diameter of the cup 3, and as shown in FIG. Atomizing air is being blown onto.

As a result, in the reference example shown in FIG. 5, the blowing direction of the atomizing air passes outside the peripheral portion of the cup 3, whereas in the reference example shown in FIG. The atomizing air can be directly blown to the tip of the peripheral edge of the paint, and the atomization of the paint can be further promoted. .

Further, in FIG. 11, the diameter of the atomizing air outlet 6 is made smaller than the outer diameter of the cup 3, and
As shown in (b), the pattern width of atomizing air can be increased by twisting the air and directing it outward. The pattern forming air may be twisted in the same manner as shown in the figure.

Further, in FIG. 12, the blowing direction of the atomizing air is twisted in the opposite direction with respect to the rotating direction of the cup 3 indicated by the arrow P. Although the power of the air motor is slightly lost, 3 increases the relative velocity of the atomizing air, which further promotes atomization of the paint.

Further, in FIG. 13, the blowing direction of atomizing air and the blowing direction for pattern formation are twisted in the same direction with respect to the rotating direction P of the cup.
The suction force due to the negative pressure in front of
A larger paint pattern can be formed.

Furthermore, FIG. 14 has the same effect as the reference example shown in FIG. 12 and the same effect as the reference example shown in FIG.

Next, FIG. 9 is a view showing another reference example of the shape of the atomizing air outlet 6 according to the present invention, in which the center axis of the ring-shaped member 15 is arranged inside the ring-shaped member 15. On the other hand, a large number of grooves 19 are formed in an oblique direction, a slight gap t is formed between the groove 19 and the inner diameter portion 18 of the head member 12, and then the head member 12 is incorporated.

As a result, the annular thin-film atomizing air coming out of the gap t is twisted along the outer peripheral portion thereof, so that
The air from each atomizing air outlet 6 does not interfere with each other, and the air emitted from the outlet does not diffuse,
Air with less energy loss can be concentrated on the peripheral edge of the cup.

FIG. 15 shows an example of control of atomizing air and coating pattern forming air of the apparatus according to the present invention.

In FIG. 15, the paint condition setting section 21 is used to set paint conditions such as paint type, viscosity, and dilution solvent ratio.
To do. Further, the coating condition setting unit 22 sets the coating conditions such as the size, distance and temperature of the object to be coated. The condition data set in this way is sent to the air controller 23, and the air controller 23 determines the optimum pressure and flow rate of the atomizing air and the coating pattern forming air based on this data, Control signals are sent to the atomizing air adjusting unit 25 and the coating pattern forming air adjusting unit 26, respectively.

The pressure and flow rate of the air sent from the air source 24 to the atomizing air adjusting section 25 and the coating pattern forming air adjusting section 26 are adjusted by receiving a control signal from the air controller 23. Is blown out from each atomizing air outlet 6 and coating pattern forming air 7 via the chamber.

By independently controlling the pressure and flow rate of the atomizing air and the coating pattern forming air in this manner, finer adjustments can be made, the quality of the coating is stabilized, and the coating efficiency is improved. Is possible.

In the reference example described above,
Although the shape of the coating pattern forming air outlet row composed of a plurality of coating pattern forming air outlets 6 is a perfect circle concentric with the rotation axis 4 of the cup 3, this may be an ellipse or a polygon.

16 and 17 are explanatory views showing an embodiment of the rotary atomizing electrostatic coating apparatus according to the present invention, and as shown in FIGS. 16 and 17 (a), a circular shape Concentric circles are formed on the outer circumference of the atomizing air outlet row composed of a plurality of atomizing air outlets 6 arranged on the circumference around the rotation axis 4 of the cup 3 having the air outlets. The head member 12 is provided with a coating pattern forming air outlet row composed of a plurality of coating pattern forming air outlets 7 each having a circular air outlet. At the same time, the sum of the diameter of the coating pattern forming air outlet 7 and the area of the coating pattern forming air outlet 7 is determined by the diameter of the atomizing air outlet 6 and the atomizing air outlet 6 Is larger than the total area of the outlets.

For example, in FIG. 17, the diameter of the coating pattern forming air outlet 7 is 2.
It is 5 times. The number of atomizing air outlets 6 is 72
The number of coating pattern forming air outlets 7 is 36, and the total of the outlet areas of the coating pattern forming air outlets 7 is about three times the total of the atomizing air outlet 6 outlet areas. Has become.

The air velocity when the nozzle diameter of the air outlet or the total area of the air outlets is generally different will be described.

FIG. 21 shows the air velocity at the coating surface position with respect to the diameter of the air outlet or the total area of the air outlets.

From this figure, it can be seen that the larger the diameter of the air outlets or the sum of the areas of the air outlets, the higher the air velocity at the coating surface position. Therefore, since the velocity of the air is almost equal to the velocity of the paint particles, the larger the diameter of the air outlet or the sum of the areas of the air outlets, the faster the paint particles collide with the coated surface. As a result, when a glittering material such as a metallic paint is used, the glittering material in the paint spreads more horizontally with respect to the coated surface, which improves the tint of the coating.

On the other hand, FIG. 22 shows the air velocity at the peripheral portion of the cup 3 with respect to the diameter of the air outlet or the total area of the air outlets.

From this figure, it is understood that the larger the diameter of the air outlet or the sum of the areas of the air outlets, the higher the air velocity at the coating surface position immediately after the air outlet. The paint is atomized by the centrifugal force generated by the rotation of the cup and the action of the air blown on the peripheral edge of the cup. As a result, the larger the diameter of the air outlets or the total sum of the areas of the air outlets, that is, the lower the air velocity at the peripheral edge of the cup, the larger the paint particles become, and the sharpness of the paint surface with a strong correlation with the paint particles is Will be reduced.

From the above results, there is a single row of air outlets on the outer circumference of the cup, that is, a conventional rotary atomizing electrostatic coating device that performs atomization and coating pattern forming operations by a single row of air outlets. Then, it is found that it is difficult to simultaneously adjust and improve the tint of the painted surface and the atomization of the paint by the air pressure. In particular, when the atomization degree of the paint particles decreases, raising the air pressure to satisfy the sharpness will give an air velocity that is higher than necessary for the tint quality of the painted surface. The number of paint particles that do not adhere to the surface and scatter increases, and the coating efficiency of the paint decreases.

FIG. 17 shows the blowing directions of the atomizing air 14 and the coating pattern forming air 13 at intervals of 90 degrees. As shown in FIG.
The reason why the direction of the atomizing air is opposite to the direction P of rotation of the cup is that the atomization of the paint is smaller than that of the direction P of rotation of the cup, as described in the reference example of FIG. Because it can be promoted.

In the rotary atomizing electrostatic coating device shown in FIG.
Atomizing air outlet 6 and coating pattern forming air outlet 7
And the diameter of the atomizing air outlet 6 and the sum of the air outlet areas are made relatively small, and the diameter of the coating pattern forming air outlet 7 and the sum of the air outlet areas are independently set. By increasing the size relatively, the air velocity becomes faster at the peripheral edge of the cup and the atomization of the paint is promoted, and at the same time, the paint velocity near the coated surface becomes faster and the luster material in the paint becomes As a result, it spreads more horizontally, and as a result, both the sharpness of the paint surface and the tint of the paint, which have a strong correlation with the paint particles, are improved.

FIG. 18 is a diagram showing the flow of the air blown out from the rotary atomizing electrostatic coating apparatus shown in FIGS. 16 and 17 in the direction of the object to be coated. Atomization air 14 blown out from the atomization air blowout port 6 having a small sum of the diameter of each of the blowout ports and the area of each blowout port.
And is carried to the object to be coated by the coating pattern forming air 13 blown out from the coating pattern forming air outlet 7 which has a large sum of the diameter of the outlet and the area of each air outlet. The coating particles collide with the coating surface W to form a coating pattern.

Further, the twist angle of the coating pattern forming air 13 with respect to the rotating shaft 4 of the cup 3 is determined by the atomizing air 1
It is larger than the twist angle of 4. Therefore, the paint particles in the vicinity of the object to be coated are attracted to the outside where the air velocity is high, so that the paint can be uniformly and widely applied.

Furthermore, by appropriately adjusting the nozzle diameters of the atomizing air outlet 6 and the coating pattern forming air outlet 7 or the sum of the areas of the respective air outlets, the sharpness and tint of the coated surface can be improved. Each adjustment can be made more finely, and as shown in FIG. 23, it is possible to use only one air flow path 11 to the atomizing air outlet 6 and the coating pattern forming air outlet 7.

FIG. 19 is an explanatory view showing still another embodiment of the rotary atomizing electrostatic coating apparatus according to the present invention, which is used for forming a coating pattern and is constituted by a plurality of air outlets 7A for forming a coating pattern. A coating pattern forming air outlet row composed of a plurality of coating pattern forming air outlets 7B is further provided on the outer periphery of the air outlet row.

Further, in this rotary atomizing electrostatic coating apparatus, the air outlets 6, 7A and 7B are respectively formed by the atomizing air outlet 6, the inner coating pattern forming air outlet 7A and the outer coating pattern forming portion. The diameter of the air outlets and the total of the air outlet areas in each air outlet row increase in the order of the air outlets 7B.

Here, FIG. 19 shows the atomizing air 14, the inner coating pattern forming air 13A and the outer coating pattern forming air 13B at every 90 degrees, and FIG. It is explanatory drawing which shows the flow of each blowing air toward a to-be-coated article, and the spreading | spreading of air is large, so that the blowing air on the outer side. Therefore, the paint can be applied uniformly and widely.

Further, in the embodiment described above, since the twist angles of the atomizing air outlet and the coating pattern forming air outlet are constant, the coating pattern is a perfect circle. By changing all or some of the twist angles of both air outlets, it is possible to make the projection of air on the surface of the object to be coated an ellipse or a polygon. Further, from FIG. 16 to FIG. In the embodiment, each air outlet is a circular nozzle, but the air outlet 6 for atomizing the paint is used.
Alternatively, the coating pattern forming blow-out port 7 may be formed of the slit-like narrow gap shown in FIG.

[0080]

According to the rotary atomizing electrostatic coating method of the first aspect of the present invention and the rotary atomizing electrostatic coating apparatus of the fourth aspect of the invention, the atomizing air and It is possible to separate each function of the paint pattern forming air, and as a result, it is possible to accelerate the atomization of the paint by the atomizing air, and independently of this, the paint pattern forming air is formed by the paint pattern forming air. You can
In addition, the larger the sum of the diameter of the coating pattern forming air outlets and the coating pattern forming air outlet area in the coating pattern forming air outlet row, the greater the flow velocity of air in the vicinity of the coating surface. The speed of the paint particles that collide with the paint surface increases, and as a result, when metallic paint is used as the paint, it is possible to easily spread the glitter material in the paint horizontally with respect to the paint surface. In addition, the smaller the sum of the diameter of the atomizing air outlets and the area of the atomizing air outlets in the row of atomizing air outlets, the smaller the total flow velocity of the air at the peripheral portion of the atomizing head. Since it is relatively increased, atomization of the paint at the peripheral portion of the atomizing head can be promoted, and the sharpness of the paint surface, which has a strong correlation with the size of the paint particles, can be further improved. It is brought about.

[0081]

According to the rotary atomizing electrostatic coating method of the second aspect of the present invention and the rotary atomizing electrostatic coating apparatus of the sixth aspect, when the coating pattern forming air is blown, the blowing direction is rotated. The twisting direction with respect to the shaft causes a certain amount of negative pressure to be generated inside the air layer formed by the paint pattern forming air, preventing paint particles from scattering outside the air layer. Further, since the center of this negative pressure exists at a certain distance in front of the cup, it is possible to prevent the paint from adhering to the inner surface of the cup.

According to the rotary atomizing electrostatic coating method of the third aspect of the present invention and the rotary atomizing electrostatic coating apparatus of the seventh aspect, the twisting direction and / or the twisting angle of the atomizing air outlet can be adjusted. Adjustment makes it possible to adjust the pressure in front of the cup, and as a result, the excellent effect of adjusting the size of the coating pattern is brought about.

[0084]

According to the rotary atomizing electrostatic coating apparatus of the fifth aspect of the present invention, two or more rows of coating pattern forming air outlets are arranged on the outer periphery of the atomizing air outlet, and the atomization is performed. From the air outlet row for use in air to the outer air outlet row for painting pattern formation, the sum of the outlet diameters and outlet areas in each outlet row is increased in order to increase the air spread toward the outside. Since the size can be increased, the excellent effect that the paint can be applied to the painted surface more uniformly and widely is brought about.

According to the rotary atomizing electrostatic coating apparatus of the eighth aspect of the present invention, the atomizing air blowout port has a blowing direction which is twisted with respect to the rotation axis and which is the rotating direction of the atomizing head. By arranging so as to be arranged in the opposite direction, the excellent effect that the paint can be atomized with a lower air flow rate and a smaller air flow rate is brought about.

According to the rotary atomizing electrostatic coating apparatus of the ninth aspect of the present invention, the atomizing air outlet is configured to have a narrow slit-like narrow gap in the circumferential direction. Since the flow rate of the use air increases, but the flow rate itself decreases, it is possible to further promote atomization of the paint, and it is possible to prevent the atomized paint from scattering. As described, the width of the slit-shaped narrow gap at this time can be optimized by setting the width to 5 μm to 200 μm.

According to the eleventh aspect of the rotary atomizing electrostatic coating device of the present invention, there is obtained a rotary atomizing electrostatic coating device having the same effects as the rotary atomizing electrostatic coating device according to the seventh aspect. Will be done.

According to the twelfth aspect of the rotary atomizing electrostatic coating device of the present invention, the atomizing air outlet and the flow passage communicating with the atomizing air outlet are provided with an annular gap in the inner periphery thereof. The air from each atomizing air outlet can be a very thin annular air layer, and advances toward the cup peripheral edge with the outer peripheral portion of the air layer twisted with respect to the rotation axis. Therefore, it is possible to prevent the air from the atomizing air outlets from interfering with each other and diffusing.

According to the rotary atomizing electrostatic coating device of the thirteenth aspect of the present invention, the twisting direction of the atomizing air and the twisting direction of the coating pattern forming air are opposite to each other. Since the relative speed between the atomizing air and the coating pattern forming air can be increased, the negative pressure in the space sandwiched between the atomizing air and the coating pattern forming air should be increased. It is possible to obtain the excellent effect that it is possible to prevent the paint particles from scattering due to the suction force due to the increased negative pressure.

According to the rotary atomizing electrostatic coating device of the fourteenth aspect of the present invention, the twisting direction of the atomizing air and the twisting direction of the coating pattern forming air are the same. Since the negative pressure in front of the cup can be made relatively small, an effect that a larger coating pattern can be formed can be obtained.

According to the rotary atomizing electrostatic coating device of the fifteenth aspect of the present invention, the twist angle of the coating pattern forming air outlet is set to be larger than the twist angle of the atomizing air outlet. Allows the flow velocity of the air on the outer side to be increased relatively, and as a result, the paint particles in the vicinity of the painted surface are attracted to the outer side where the flow rate is fast, so that the paint can be applied to the painted surface evenly and widely. The excellent effect that it can be brought.

According to the sixteenth aspect of the present invention, the atomizing air outlets and / or the coating pattern forming air outlets are elliptical or polygonal. The effect of being able to form a coating pattern of a desired shape on the coated surface is brought about.

With the rotary atomizing electrostatic coating apparatus according to the seventeenth aspect of the present invention, with the above-mentioned configuration, it is possible to form a desired coating pattern such as an ellipse or a polygon. Is brought about.

[0095]

[Brief description of drawings]

FIG. 1 is a sectional explanatory view showing a reference example of a rotary atomizing electrostatic coating apparatus according to the present invention.

2A and 2B are a front explanatory view (FIG. 2A) and a side explanatory view (FIG. 2) showing how the atomizing air and the pattern forming air are blown out in the rotary atomizing electrostatic coating apparatus of FIG. 1;
(B)).

FIG. 3 is a sectional explanatory view showing another reference example of the rotary atomizing electrostatic coating device according to the present invention.

4 is a perspective explanatory view showing a ring-shaped member used in the rotary atomizing electrostatic coating device of FIG. 3. FIG.

5A and 5B are a front explanatory view (FIG. 5A) and a side explanatory view (FIG. 5B) showing the blowing directions of the atomizing air and the coating pattern forming air in the embodiment of FIG.

FIG. 6 is an explanatory view showing a state where air hits a peripheral edge portion of a cup in a conventional example.

FIG. 7 is an explanatory view showing a state in which air hits a peripheral portion of a cup in the rotary atomizing electrostatic coating device according to the present invention.

FIG. 8 is a partially enlarged view of an inner peripheral side of a ring-shaped member in a reference example of the rotary atomizing electrostatic coating device according to the present invention.

FIG. 9 is a partially enlarged view of an inner peripheral side of a ring-shaped member in still another reference example of the rotary atomizing electrostatic coating device according to the present invention.

10 is a front explanatory view (FIG. 10 (a)) and a side explanatory view showing another reference example of the blowing directions of the atomizing air and the coating pattern forming air of the rotary atomizing electrostatic coating device according to the present invention. (Fig. 10 (b)).

FIG. 11 is a front explanatory view (FIG. 11A) and a side view showing still another reference example of the blowing directions of the atomizing air and the coating pattern forming air of the rotary atomizing electrostatic coating device according to the present invention. It is a figure (FIG.11 (b)).

FIG. 12 is a front explanatory view (FIG. 12A) and a side view showing still another reference example of the blowing directions of the atomizing air and the coating pattern forming air of the rotary atomizing electrostatic coating device according to the present invention. It is a figure (FIG.12 (b)).

13 is a front explanatory view (FIG. 13A) and a side view showing still another reference example of the blowing directions of the atomizing air and the coating pattern forming air of the rotary atomizing electrostatic coating device according to the present invention. It is a figure (FIG.13 (b)).

FIG. 14 is a front explanatory view (FIG. 14A) and a side view showing still another reference example of the blowing directions of the atomizing air and the coating pattern forming air of the rotary atomizing electrostatic coating device according to the present invention. It is a figure (FIG.14 (b)).

FIG. 15 is an explanatory diagram showing a configuration of an air control unit of the rotary atomizing electrostatic coating device according to the present invention.

FIG. 16 is an explanatory view showing an embodiment of the rotary atomizing electrostatic coating device according to the present invention.

FIG. 17 is a front explanatory view ((a) of FIG. 17) and a side explanatory view (FIG. 17 (shown in FIG. 17 ( b)).

FIG. 18 is an explanatory view showing the flows of atomizing air and coating pattern forming air in the direction of the coated object in the rotary atomizing electrostatic coating apparatus of FIG. 16.

19 is a front explanatory view (FIG. 19 (a)) and a side explanatory view showing the blowing directions of atomizing air and coating pattern forming air in another embodiment of the rotary atomizing electrostatic coating device according to the present invention. (Fig. 19 (b)).

20 is an explanatory diagram showing the flow of atomizing air and coating pattern forming air in the direction of the coated object in the rotary atomizing electrostatic coating apparatus of FIG.

FIG. 21 is an explanatory diagram showing a relationship between a diameter of an air outlet or a total of outlet areas in each outlet row and an air velocity in the vicinity of a coated surface.

FIG. 22 is an explanatory diagram showing the relationship between the diameter of the air outlets or the total of the outlet areas in each outlet row, and the air velocity at the peripheral edge of the cup.

FIG. 23 is a sectional view showing still another embodiment of the rotary atomizing electrostatic coating device according to the present invention.

FIG. 24 is a cross-sectional explanatory view showing an example of a conventional rotary atomizing electrostatic coating device.

25 is a perspective explanatory view showing a main part of the rotary atomizing electrostatic coating device of FIG. 24. FIG.

FIG. 26 is a cross-sectional explanatory view showing another example of a conventional rotary atomizing electrostatic coating device.

27 is a front explanatory view of the rotary atomizing electrostatic coating device in FIG. 26. FIG.

28 is a side view for explaining the rotary atomizing electrostatic coating device in FIG. 26. FIG.

FIG. 29 is a perspective view schematically showing the flow of shaping air in a conventional example.

FIG. 30 is an explanatory view showing still another example of the conventional rotary atomizing electrostatic coating device.

Front page continuation (72) Inventor Shuji Torii 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (56) Reference JP 61-74666 (JP, A) JP 4-22451 (JP, A) JP 3-101858 (JP, A) JP 58-183958 (JP, A) JP 7-256156 (JP, A) JP 63-49270 (JP, A) Actual Publication 37-9349 (JP, Y1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B05B 5/00-5/16 B05D 1/04

Claims (17)

(57) [Claims] 1. A cup-shaped atomizing head is fixed to the tip of a rotating shaft, paint is supplied to the inner peripheral surface of the atomizing head and atomized by centrifugal force, and the atomization is performed from the peripheral edge of the tip of the atomizing head. In the rotary atomization electrostatic coating method that discharges the modified paint, the sum of the diameter of the coating pattern forming air outlets and the total area of the coating pattern forming air outlets in the coating pattern forming air outlet row is atomized. The diameter of the atomizing air outlets and the total area of the atomizing air outlets in the atomizing air outlet row are formed to be larger than the sum of the atomizing air outlets, and from the outer periphery behind the tip of the atomizing head to the peripheral edge of the atomizing head. Atomizing air is blown from multiple positions toward the front of the atomizing head, and air is sprayed toward the front of the atomizing head from multiple positions on the outer periphery of the multiple positions behind the tip of the atomizing head. Rotating atomization electrostatic painting characterized by blowing out Law. 2. When blowing air for forming a coating pattern,
The rotary atomizing electrostatic coating method according to claim 1, wherein the blowing direction is a twisting direction with respect to the rotation axis. 3. The rotary atomizing electrostatic coating method according to claim 2, wherein, when the atomizing air is blown, the blowing direction is a twisting direction with respect to the rotation axis. 4. The paint supplied to the inner peripheral surface of a cup-shaped atomizing head fixed to the tip of a rotary shaft is atomized by centrifugal force, and the atomized paint is discharged from the peripheral edge of the tip of the atomizing head. In the rotary atomizing electrostatic coating device, the sum of the diameter of the coating pattern forming air outlet and the coating pattern forming air outlet area in the coating pattern forming air outlet row is atomized in the atomizing air outlet row. A plurality of fogs that are formed to be larger than the sum of the diameter of the air outlet for atomization and the area of the air outlet for atomization, and blow out air toward the peripheral portion of the atomizing head on the outer periphery behind the tip of the atomizing head. A coating consisting of an atomizing air outlet row consisting of atomizing air outlets and a plurality of coating pattern forming air outlets that further blows air toward the front of the atomizing head on the outer periphery of this atomizing air outlet. Arrange a row of air outlets for pattern formation Rotary atomizing electrostatic coating apparatus, characterized in that. 5. The coating pattern forming air outlet row is arranged in two or more rows on the outer periphery of the atomizing air outlet, and from the atomizing air outlet row to the outer coating pattern forming air outlet row. 5. The rotary atomizing electrostatic coating device according to claim 4, wherein the sum of the diameters of the outlets and the area of the outlets in each of the outlet rows is increased in order. 6. The rotary atomizing electrostatic discharge according to claim 4, wherein the air outlet for forming the coating pattern is arranged so that its blowing direction is twisted with respect to the rotating shaft. Coating equipment. 7. The rotary atomizer according to claim 4, wherein the atomizing air outlet is arranged so that its blowing direction is twisted with respect to the rotation axis. Electrostatic coating device. 8. The rotary atomizing electrostatic coating according to claim 7, wherein the atomizing air outlet is arranged so that its blowing direction is opposite to the rotating direction of the atomizing head. apparatus. 9. The atomizing air outlet has a narrow slit-like narrow gap in the circumferential direction.
9. The rotary atomizing electrostatic coating device according to any one of 1 to 8. 10. The width of the slit-like narrow gap is 5 μm to
The rotary atomizing electrostatic coating device according to claim 9, wherein the rotary atomizing electrostatic coating device has a thickness of 200 μm. 11. The rotary atomizing electrostatics according to claim 9, wherein the direction of the flow path communicating with the atomizing air outlet is twisted with respect to the rotation axis. Coating equipment. 12. The rotary atomizing electrostatic coating according to claim 9, wherein an annular gap is formed in the inner circumference of the atomizing air outlet and the flow path communicating with the atomizing air outlet. apparatus. 13. The rotary atomizing electrostatic coating according to claim 7, wherein the twisting direction of the atomizing air and the twisting direction of the coating pattern forming air are opposite to each other. apparatus. 14. The rotary atomizing electrostatic coating device according to claim 7, wherein the twisting direction of the atomizing air and the twisting direction of the coating pattern forming air are in the same direction. . 15. The rotary atomization electrostatic as claimed in claim 7, wherein the twist angle of the coating pattern forming air outlet is larger than the twist angle of the atomizing air outlet. Coating equipment. 16. The rotary mist according to claim 4, wherein the atomizing air outlet row and / or the coating pattern forming air outlet row is oval or polygonal in shape. Electrostatic coating equipment. 17. The method according to claim 4, wherein all or some of the twist angles of the respective air outlets in the atomizing air outlet row and / or the coating pattern forming air outlet row are changed. The rotary atomizing electrostatic coating device according to any one of the claims.