JP2622611B2 - Bell type rotary coating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a bell type rotary coating apparatus used as, for example, an electrostatic coating apparatus.

[Conventional technology]

In general, a bell-type electrostatic coating apparatus rotates a bell-type rotary atomizing head at a high speed and applies a high voltage between the bell-shaped electrostatic atomizing head and an object to be coated to supply paint to a paint smoothing surface of the rotary atomizing head. Then, the atomized charged paint particles are fly-coated on the object along an electrostatic field formed between the atomized charged paint particles and the object located axially forward.

FIGS. 6 and 7 show an electrostatic coating apparatus using such a bell-shaped rotary atomizing head.

First, in FIG. 6, reference numeral 1 denotes a casing which forms a main body of the coating apparatus. The casing 1 includes an air bearing 2, an air motor 3, a paint valve (not shown), and the like. A high voltage is applied via a high voltage cable (not shown).

Reference numeral 4 denotes a rotating shaft rotatably supported by the air bearing 2. The tip of the rotating shaft 4 protrudes out of the casing 1, and its base end is attached to the air motor 3, which is driven by the air motor 3 to rotate at high speed. It has become.

Reference numeral 5 denotes a bell-shaped rotary atomizing head provided at the tip of the rotary shaft 4. The outer peripheral surface of the rotary atomizing head 5 is cylindrical or cup-shaped, and the inner peripheral surface is a paint smoothing surface. ing. Reference numeral 6 denotes a center feed type paint supply pipe provided through a rotary shaft. The tip of the paint supply pipe 6 extends into the rotary atomizing head 5, and a paint valve is provided at the base end side. , And is connected to the paint tank via the paint pipe.

Reference numeral 7 denotes a shaping air cover which is provided on the casing 1 so as to surround the rotary atomizing head 5 from the outer periphery of the casing 1 and has an inner portion formed of an insulating resin serving as an air passage. Cover body 7A
The first and second shaping air nozzle portions 7 are provided at the end of the cover main body 7A so as to surround the rotary atomizing head 5.
B, 7C, and each of the shaping air nozzle portions 7B, 7C
The leading end between them forms a shaping air ejection port 7D, which ejects shaping air in the direction indicated by the dotted arrow a. In the drawing, reference numeral 8 denotes an object to be coated located in front of the rotary atomizing head 5.

In the electrostatic coating apparatus configured as described above, the rotating shaft 4 and the rotating atomizing head 5 are charged to a high voltage by applying a high voltage to the casing 1, and an electrostatic field is formed between the rotating shaft 4 and the rotating atomizing head 5. I do. At the same time, the rotating shaft 4 and the rotary atomizing head 5 are rotated at high speed by the air motor 3 in the casing 1.

In this state, by opening the paint valve, paint is supplied to the rotary atomizing head 5 through the paint supply pipe 6 and spread along the paint smoothing surface, and then charged from the discharge edge. Spray as paint particles. At this time, since the rotary atomizing head 5 is rotating at a high speed, the paint particles tend to be blown radially from the discharge edge by the centrifugal force. However, since the shaping air is ejected from the air ejection port 7D of the shaping air cover 7 in the direction of the arrow a, the charged paint particles are pattern-formed so as to be sprayed forward by the shaping air, as shown in FIG. The paint sprays in a paint spray pattern in the direction indicated by the solid arrow b, flies along the electrostatic field, and is applied to the workpiece 8. Since the paint spray pattern b is formed by shaping air, the coating pattern on the object 8 is a circular pattern.

[Problems to be solved by the invention]

However, in the electrostatic coating apparatus according to the related art, the shaping air that is jetted from the air jet port 7D of the shaping air cover 7 in the direction of arrow a is determined so as to form a circular coating pattern.

As described above, the coating pattern is determined by the air pressure of the shaping air. However, when the coating particles are sprayed from the discharge edge of the rotary atomizing head 5, the particle size of the coating particles is not uniform. It is. As a result, a large centrifugal force acts on large-diameter paint particles, i.e., rough paint particles, and tends to be scattered away. It will not be.

As a result, despite the fact that the shaping air is being ejected from the shaping air cover 7, the shaping air has a small air pattern forming effect on the rough paint particles in the forward direction, and the rotary atomizing head 5 has a high speed. When rotating, a difference occurs in the centrifugal force acting on the paint particles according to the particle size of the paint particles. For this reason, as shown in FIGS. 6 and 7, the coating pattern of
The fine paint particles 9 are applied at the central portion of the shaft, and the rough paint particles 10 are applied at the peripheral portion.

In this way, the central portion coated with the fine paint particles 9 has a uniform film thickness (hiding film thickness) for hiding the base of the article 8 to be coated, and has a good finish on the surface called gloss. On the other hand, there is a problem that not only the concealed film thickness becomes non-uniform at the peripheral portion where the rough paint particles 10 are applied, but also the surface finish is poor and a good coating film cannot be obtained.

The present invention has been made in view of such problems of the related art, and has made it possible to easily change a coating pattern without using shaping air and to obtain a uniform coating film. An object of the present invention is to provide a bell-shaped rotary coating device.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a casing having a built-in air motor, a rotating shaft that has a distal end projecting outside the casing and a base end located in the casing and is driven to rotate by the air motor; A bell-shaped rotary atomizing head having a cylindrical or cup-shaped outer peripheral surface side and a paint smoothing surface formed on an inner peripheral surface side, and supplying paint to the rotary atomizing head. In the bell type rotary coating apparatus comprising a paint supply pipe to perform, a vane for generating an air flow flowing in an axial direction toward an object to be coated is arranged on an outer peripheral surface side of the rotary atomizing head, and the casing is provided in the casing. A shielding cylinder for adjusting the outflow air amount is provided so as to surround the outer periphery of the rotary atomizing head and to be movable in the front-rear direction of the rotary atomizing head.

[Action]

With this configuration, when the rotary atomizing head rotates at a high speed, the blade generates an axial air flow toward the object to be coated, and this air flow serves as shaping air to form a coating pattern. By mixing the rough and fine paint particles, a uniform coating film can be obtained. At this time, by moving the shielding cylinder in the front-back direction of the rotary atomizing head, the amount of air flowing out by the blade can be adjusted, and the shaping air pressure can be controlled to make the coating pattern variable.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 5.

First, in FIGS. 1 and 2, reference numeral 11 denotes a bell-shaped rotary atomizing head used in the present embodiment, 12 denotes an atomizing head body which forms the main body of the rotary atomizing head 11, and The outer peripheral surface 12A has a cylindrical shape or a cup shape. Meanwhile, the atomizing head body
The inner peripheral surface side of 12 has a female screw on one side in the axial direction with respect to a rim 12B provided in the middle in the axial direction.
It becomes C, and the other side in the axial direction spreads like a bosh.
2D, the tip of the smoothing surface 12D becomes the emission edge 12E,
A hub member mounting groove 12F is formed in the middle of the smoothing surface 12D. The atomizing head main body 12 is attached to the distal end side of the rotating shaft 20 via the female screw of the attaching portion 12C. In this attached state, the distal end of the later-described paint supply pipe 21 has a rim.
It extends to a position slightly protruding from 12B. Note that a V-shaped groove may be formed on the entire inner circumference of the discharge edge 12E.

Reference numeral 13 denotes a hub member which is formed in a substantially disk shape and is fitted in the hub member mounting groove 12F of the atomizing head main body 12.
One side is a convex conical paint supply surface to which the paint from the paint supply pipe 4 is supplied, and the other side is a flat surface 13B. Reference numerals 14, 14, ... denote a plurality of paint outflow holes formed in the periphery of the hub member 13 over the entire circumference, and each of the paint outflow holes 14 is in contact with the smoothing surface 12D and communicates with the front and rear of the smoothing surface 12D. It is supposed to.

Are blades 15 provided on the outer peripheral surface 12A side of the atomization head main body 12 and slightly behind the discharge edge 12E. In the case of this embodiment, each of the blades 15 They are arranged at 45 ° intervals and at an angle of 45 ° to the axis of the atomizing head body 12. When the rotary atomizing head 11 is rotated at a high speed, an axial air flow A toward the workpiece 8 is generated. Here, the blade 15 of the present embodiment is an atomizing head main body.
It is constituted by arranging rectangular bodies slightly protruding from the outer peripheral surface 12A of the 12 at an equal interval diagonally.
This does not cause a large resistance to the high-speed rotation, and the shape is such that an air flow A having a required air pressure according to the projecting length of the shielding cylinder 22 described later can be generated.

Next, reference numeral 16 denotes a casing constituting the main body of the coating apparatus according to the present embodiment, and an air bearing 17, an air motor 18, a paint valve (not shown) and the like are built in the casing 16 similarly to the prior art. At the same time, although a high voltage is applied to the casing 16 via a high-voltage cable (not shown), a shaping air cover according to the prior art is not provided in this embodiment. In addition, 19 is a casing
Four air outlets opened at four locations so as to be orthogonal to the front end face of the air outlet 16, and each air outlet 19 exhausts the driving air of the air bearing 17 and the air motor 18 and is usually used as a part of the shaping air. I have. Reference numeral 20 denotes a rotating shaft rotatably supported by an air bearing 17, and a casing 16
The above-mentioned rotary atomizing head 11 is attached to the outside, and its proximal end is attached to the air motor 18. Reference numeral 21 denotes a center-feed type paint supply pipe provided through the rotary shaft 20.A tip of the paint supply pipe 21 extends into the rotary atomizing head 11, and a base end thereof is provided with a paint valve. It is connected.

Reference numeral 22 denotes a cylindrical shielding tube provided at the front end side of the casing 16 so as to be movable in the front-rear direction on the outer peripheral side thereof, and a distal end side 22A of the shielding cylinder 22 surrounds the outer peripheral side of the rotary atomizing head 11. The base end side 22B is slidably supported on the outer periphery of the casing 16 via a slide bearing 23 such as Teflon or the like, so as to adjust the outflow air amount as described later.

Reference numeral 24 denotes a cylinder device located on the rear side of the shielding cylinder 22 and attached to the outer periphery of the casing 16. The cylinder device 24 includes a cylinder tube 24A in which a piston (not shown) is slidably inserted. , The piston rod 24B whose base end is fixed to the piston and whose tip projects out of the cylinder tube 24A
The distal end side of the piston rod 24B is fixed to the base end side 22B of the shielding cylinder 22 via a bracket 25. The cylinder device 24 moves the shielding cylinder 22 to an arbitrary position between the states shown in FIGS. 3 and 4 by supplying and discharging air from an air control valve (not shown). Has become.

Further, reference numeral 26 denotes a ring-shaped exhaust air shielding plate provided at the front end of the casing 16 so as to surround the air exhaust port 19, and the exhaust air shielding plate 26 rotates the exhaust air from the air exhaust port 19 into a rotary atomizer. The flow is prevented from flowing toward the head 11 and is rectified so as to flow out from the gap 26A on the outer periphery of the rotating shaft 20 in the direction of arrow B in the drawing.

The present embodiment is configured as described above, and its operation will be described next.

First, referring to FIG. 3, an operation in the case where the shielding cylinder 22 is advanced so as to surround the outer periphery of the rotary atomizing head 11 to the vicinity of the blade 15 to obtain a large-diameter circular coating pattern will be described.

That is, when air is supplied to and discharged from the cylinder device 24 to extend the piston rod 24B, the shielding cylinder 22 is advanced by the cylinder device 24 to the state shown in FIG.

In this state, a high voltage is applied to the casing 16, and the rotating shaft 20 and the rotary atomizing head 12 are rotated at a high speed by the air motor 18. When the rotary atomizing head 12 is rotated at a high speed in this manner, the blades 15 arranged on the outer peripheral side of the atomizing head main body 12 generate an air flow in the direction of arrow A.

However, when the shield cylinder 22 is advanced to the position shown in FIG. 3, the flow of the inflow air flowing toward the blades 15 of the rotary atomizing head 11 is indicated by a dotted arrow C in FIG. As a result, sufficient air cannot flow into the blade 15 because of the obstruction of the shielding cylinder 22, and the air flow A generated from the rotary atomizing head 11 by the blade 15 is weak and the air pressure is low.

In this state, when the paint is supplied from the paint supply pipe 21 to the rotary atomizing head 11 and the paint is sprayed from the discharge edge 12E of the atomizing head main body 12, the paint particles will be blown radially by centrifugal force. However, a relatively weak air flow A forms a paint spray pattern D which is directed obliquely forward as shown by a two-dot chain line D in the figure.

As described above, when the shielding cylinder 22 is advanced, the outflow air amount and the air pressure of the air flow A are weak, and the paint spray pattern D is not sufficiently formed in the forward direction.
Is a large-diameter circular pattern as shown by oblique lines in FIG.

Next, referring to FIG. 4, an operation in the case where the outer periphery of the rotary atomizing head 11 is retracted toward the casing 16 side to obtain a small diameter circular coating pattern will be described with reference to FIG.

That is, when air is supplied to and exhausted from the cylinder device 24 to reduce the piston rod 24B, the shielding cylinder 22 is retracted by the cylinder device 24 to the state shown in FIG.

When the rotary shaft 20 and the rotary atomizing head 12 are rotated at a high speed by the air motor 18 in this state, the blades 15 arranged on the outer peripheral side of the atomizing head main body 12 generate an air flow in the direction of arrow A '.

At this time, since the shielding cylinder 22 is retracted to the position shown in FIG. 4, the flow of the inflowing air flowing toward the blade 15 of the rotary atomizing head 11 is in the state indicated by the dotted arrow C 'in FIG. , Shielding tube
Sufficient air can flow into the blades 15 without being disturbed by the blades 22, and the blades 15 can provide a strong air flow A 'generated from the rotary atomizing head 11 and a high air pressure.

In this state, when the paint is supplied from the paint supply pipe 21 to the rotary atomizing head 11 and the paint is sprayed from the discharge edge 12E of the atomizing head main body 12, the paint particles will be blown radially by centrifugal force. However, the paint spray pattern D 'is directed forward by a strong air flow A' as shown by a two-dot chain line D 'in the figure.
The pattern is formed.

When the shield cylinder 22 is retracted in this way, the air pressure of the air flow A 'is strong, so that the paint spray pattern D' is sufficiently formed into a pattern, and the coating pattern 27 'applied to the workpiece 8 is This results in a small-diameter circular pattern as shown by oblique lines in FIG.

Thus, according to the present embodiment, the blades 15 are arranged side by side on the outer periphery of the rotary atomizing head 11, and the flow of air flowing into the blades 15 is changed to the third.
By changing the state to C in the figure or C 'in FIG. 4, the amount of air flowing into the blade 15 is adjusted.
As a result, the air flow generated by the blade 15 can be the weak air flow A shown in FIG. 3 or the strong air flow A 'shown in FIG. 4, and the air flow A or A' is used as shaping air. Thereby, the coating pattern is changed to the large diameter pattern 27 in FIG. 3 or the small diameter pattern 27 ′ in FIG.
Pattern can be formed.

Next, when the rotary atomizing head 11 is rotated at a high speed, a negative pressure region 28 is generated on the front surface side by an air pumping phenomenon as shown by a dotted line in FIG. 3 or FIG. In addition, the air pumping phenomenon is a negative pressure phenomenon that occurs when the rotary atomizing head 11 is rotated at high speed and the air in front of it is blown in the radial direction, and replenishes the front air to compensate for this negative pressure phenomenon This refers to the phenomenon of backflow.

In this state, when the paint is sprayed from the discharge edge 12E of the atomizing head body 12, the spray patterns D and D 'are in the negative pressure region due to the air pressure of the air flow A and A' by the blade 15 and the air pumping phenomenon. The paint spray pattern D,
D 'is wound in the negative pressure region 28. As a result,
The paint spray patterns D and D 'are in a spiral state, and the fine and coarse particles of the paint particles sprayed from the rotary atomizing head 11 are mixed by the above-described wrapping action to become mixed paint particles. Then, the mixed paint particles fly along the electrostatic field and are applied to the object 8, and the object 8
, The concealing film thickness can be made uniform over the entire surface, and the surface finish can be improved.

Further, in the present embodiment, a ring-shaped exhaust air shielding plate 26 is provided in the casing 16 so as to cover the air exhaust port 19, and the exhaust air is caused to flow out of the gap 26A in the direction of arrow B, as in the prior art. Prevents straight outflow.

Here, in the case of the prior art, since the exhaust air straightly flows out of the four air exhaust ports, the paint spray pattern was deformed into a petal shape as shown by a dotted line 29 in FIG. However, in this embodiment, the exhaust air shielding plate
Since it is rectified by 26 and does not flow straight out, the paint spray pattern becomes a circular pattern as shown by a solid line 30 in FIG. Therefore, in the present embodiment, a better coating film can be obtained in combination with the above-described shaping air action by the air flows A and A 'by the rotary atomizing head 11.

The present invention is not limited to the shape of the blades and the number of rows arranged in the embodiment, but may adopt various shapes and numbers, and in essence, the axial direction flowing toward the object to be coated. As long as the air flow can be generated, an axial flow blade having another shape may be used.

Further, the rotary atomizing head may have a cylindrical or cup-like shape, and includes those having a conical or hemispherical outer shape.

On the other hand, in the embodiment, the rotary shaft is fixed to the mounting portion of the atomizing head main body, and the paint supply pipe is inserted into the rotary shaft. However, the rotary shaft is mounted on the hub member, and is separated from the rotary shaft. The present invention can also be applied to a bell-type rotary atomizing head of a type configured such that the paint supply pipe disposed in the above-mentioned arrangement faces the paint supply surface of the hub member.

Further, in the embodiment, the shield cylinder is described in the state of FIG. 3 and the state of FIG. 4. However, the shield cylinder can be locked at an arbitrary position by an air control valve for supplying and discharging air to and from the cylinder device. It is.

〔The invention's effect〕

The bell-type rotary coating apparatus according to the present invention is as described in detail above, and includes a vane that generates an air flow for forming a pattern that flows in an axial direction toward an object to be coated on an outer peripheral surface side of a rotary atomizing head. Arranged in a row, the casing is provided with a shielding cylinder for adjusting the outflow air amount so as to surround the outer periphery of the rotary atomizing head and to be movable in the front-rear direction of the rotary atomizing head. The amount of air flowing out of the blade and the air pressure can be adjusted simply by moving it forward and backward, and by using this outflowing air flow as shaping air, the coating pattern can be changed according to the advance and retreat of the shielding cylinder. Using an air flow, it is possible to obtain a coating film in which paint particles with large and small particle sizes are mixed in the coating pattern of the object to be coated, and a coating film with uniform film pressure and good finish And the like.

[Brief description of the drawings]

1 to 5 relate to an embodiment of the present invention, FIG. 1 is a half sectional view of a rotary atomizing head used in the present embodiment, and FIG.
FIG. 3 is a half sectional view showing the entire configuration of the bell-shaped rotary coating apparatus according to the present embodiment with the shielding cylinder advanced, and FIG. 4 is a block diagram showing the entire configuration of the bell-shaped rotary coating apparatus. FIG. 4 is a half sectional view similar to FIG. 4 showing a state in which the cylinder is retracted, FIG. 5 is a plan explanatory view showing a change in a coating pattern depending on the presence or absence of an exhaust air shielding plate, and FIG. 6 and FIG. Involved
FIG. 6 is an overall configuration diagram of a main part of a rotary spin coating apparatus according to the prior art, in which a main part is broken, and FIG. 7 is a plan view showing a coating pattern on an object to be coated. 11 ... Rotating atomizing head, 12 ... Atomizing head body, 15 ... Feather, 16
…… Casing, 17 …… Air bearing, 18 …… Air motor,
19… Air exhaust port, 20… Rotary shaft, 21… Coating supply pipe,
22 ... Shield cylinder, 23 ... Slide bearing, 24 ... Cylinder device, 26 ... Exhaust air shield plate.

Claims (1)

(57) [Claims] A casing having a built-in air motor, a rotating shaft driven by the air motor with a distal end projecting out of the casing and a proximal end positioned in the casing, and a rotating shaft provided at a distal end of the rotating shaft. It comprises a bell-shaped rotary atomizing head having a cylindrical or cup-shaped outer peripheral surface and a paint smoothing surface formed on the inner peripheral surface, and a paint supply pipe for supplying paint to the rotary atomizing head. In a bell-type rotary coating apparatus, vanes that generate an air flow that flows in the axial direction toward the object to be coated are arranged on the outer peripheral surface side of the rotary atomizing head,
A bell-shaped rotary coating device, wherein a shielding cylinder for adjusting the amount of outflow air is provided on the casing so as to surround the outer periphery of the rotary atomizing head and to be movable in the front-rear direction of the rotary atomizing head. .