JPH0824720A - Rotary electrostatic spray coating apparatus - Google Patents

Abstract

PURPOSE:To provide a rotary electrostatic spray coating apparatus by which fine coating material spray by which coarse coating material particles are not mixed is obtained and coating quality is improved. CONSTITUTION:In a rotary electrostatic spray coating apparatus 1, on a tip surface 3c of a spray head 3, a lot of coating material guiding grooves 6 whose width and depth are gradually reduced toward the outer peripheral side are radially formed, and also an annular surface 3b extending from the inner peripheral surface 3a of the spray head 3 in the central shaft direction of the spray head 3 is provided, and coating material inflow ends to the coating material guiding grooves 6 are opened on the annular surface 3b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary atomization used for electrostatic coating which atomizes a paint and imparts an electric charge to the atomized paint particles so that the coating efficiency can be improved by the force of static electricity. The present invention relates to an electrostatic coating device, and more particularly, to a structure of a spray head of a rotary atomizing electrostatic coating device.

[0002]

2. Description of the Related Art Conventionally, an example of the rotary atomizing electrostatic coating device as described above is described in Japanese Patent Laid-Open No. 229163/1988.

FIG. 7A shows the structure of the rotary atomizing electrostatic coating device described in the above publication. The rotary atomizing electrostatic coating device 100 shown in the figure has a spray head 1 fixed to a rotary shaft 101.
02, a high voltage generator 103 for applying a high voltage between the rotary shaft 101 and the object to be coated, and a spray head 1 rotating at a high speed.
02 mainly comprises a paint supply nozzle 104 for supplying paint to the interior of the spray head 102 from the inner peripheral surface 102a to the tip 1
A plurality of V-shaped paint guide grooves 105 are formed on the conical surface 102c extending to 02b.

In the rotary atomizing electrostatic coating apparatus 100 having such a structure, the paint supplied from the paint supply nozzle 104 into the annular space 102d of the spray head 102 rotating at a high speed is the cup of the spray head 102. Inner peripheral surface 10 forming a shape
A large number of paint outflow holes 102 formed in an annular shape at the bottom of 2a.
It flows out along the inner peripheral surface 102a through e, and flows toward the tip 102b of the spray head 102 by centrifugal force.
Then, it flows from the inner peripheral surface 102a into the paint guide groove 105, is accelerated in the guide groove 105, and becomes an extremely thin thread-like paint flow to reach the tip portion 102b. The thread-like paint flow is released from the outer peripheral edge of the tip portion 102d, and then is torn to become negatively charged paint particles toward the object to which the high voltage positive side of the high voltage generator 103 is applied. It is supposed to be released.

[0005]

However, in the conventional rotary atomizing electrostatic coating device 100 described above, the inflow end of the coating material into the coating material guide groove 105 is opened on the inner peripheral surface 102a of the spray head 102. Due to this, the paint is on the inner surface 102
When flowing from a to the spray head tip portion 102b, a part of the paint flow does not flow into the paint guide groove 105 and the conical surface 1
In some cases, relatively large particles may be discharged as they are from the outer peripheral edge of the spray head tip portion 102d through the upper part of 02c, and in such a case, during the fine paint spray discharged through the guide groove 105. Since coarse paint particles are mixed together, there is a problem in that it cannot be said that coating unevenness will occur and the finish quality of the coating will not deteriorate. It has been a challenge to improve the coating quality of the electrocoating device.

FIG. 7 (b) is a schematic view for explaining the process of producing the coarse paint particles.
FIG. 8 is a view of the vicinity of the tip portion 102b of FIG. 7 as seen from the direction of arrow B in FIG.

That is, the inner peripheral surface 102a of the spray head 102
Most of the paint flow F flowing along the conical surface 10
It flows into the V-shaped paint guide groove 105 formed in 2c, is guided to the tip portion 102b of the spray head 102 while being accelerated in the guide groove 105 as described above, and becomes a very thin thread-like paint flow tip. Although it is discharged from the outer peripheral edge of the portion 102d and becomes fine paint particles m, a part of the paint flow F is indicated by an arrow in the figure because the centrifugal force is extremely strong in the vicinity of the conical surface 102c of the spray head 102. Over the boundary with the adjacent guide groove 105 as shown in FIG.
05 does not pass inside 05, flows along the conical surface 102c to the tip 102b, is not accelerated or squeezed by the guide groove 105, and remains in a relatively thick string-like shape directly outside the tip 102d. Emitted from the peripheral edge, this string-like paint flow is broken and becomes coarse paint particles d.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems in a conventional rotary atomizing electrostatic coating apparatus, and it is possible to obtain a fine coating spray which does not contain coarse coating particles. It is therefore an object of the present invention to provide a rotary atomizing electrostatic coating device capable of improving coating quality.

[0009]

According to a first aspect of the present invention, there is provided a rotary atomizing electrostatic coating device which discharges paint supplied to the inner peripheral surface of a rotating cup-shaped spray head from the peripheral portion of the tip surface of the spray head. In the rotary atomizing electrostatic coating device that atomizes by spraying, a plurality of paint guide grooves whose width and depth are gradually reduced toward the outer peripheral side are provided on the tip end surface of the spray head in the radial direction, and from the inner peripheral surface, The rotary atomization static according to claim 2 of the present invention is configured to have an annular surface extending in the direction of the central axis of the spraying head, and the inflow end of the coating material into the coating material guide groove is open to the annular surface. The electrocoating device is a rotary atomizing electrostatic coating device that sprays the paint supplied to the inner peripheral surface of the rotating cup-shaped spraying head from the peripheral portion of the spraying head tip surface, and atomizes the paint. A plurality of paint guide grooves are provided in the radial direction whose width and depth gradually decrease toward the outer circumference. In addition, it has an annular surface located outside the surface extending the inner peripheral surface and extending in the central axis direction of the spray head, and the annular surface has an inflow end of the paint into the paint guide groove. Is characterized in that it is opened, and the structure of such a rotary atomizing electrostatic coating device is a means for solving the above-mentioned conventional problems.

In the embodiment of the rotary atomizing electrostatic coating apparatus according to the present invention, the rising portion of the annular surface can be curved surface finish or the paint guide groove can be V-shaped. .

Further, in the embodiment of the rotary atomizing electrostatic coating apparatus according to the second aspect of the present invention, the corners from the inner peripheral surface to the annular surface can be curved.

[0012]

In the rotary atomizing electrostatic coating apparatus according to the first aspect of the present invention, the cup-shaped spray head has an annular surface extending from the inner peripheral surface of the spray head toward the central axis of the spray head. Since the inflow end of the paint to the paint guide groove is open on the annular surface, the paint supplied from the paint supply nozzle spreads along the inner peripheral surface of the spray head through the paint outflow hole of the spray head,
An attempt is made to flow into the paint guide groove formed on the tip end surface of the spray head, but since the annular surface where the paint inflow end into the paint guide groove is formed extends in the central axis direction of the spray head, Since the surface suppresses the progress of the paint, the speed decreases, and the paint spreads in the circumferential direction along the annular surface, all the paint does not pass over the boundary between the adjacent guide grooves and all the paint is guided. It will flow into the groove. The paint that has flowed into the paint guide groove is squeezed by the paint guide groove whose width and depth gradually decrease toward the outer peripheral side of the spray head and is guided to the outer peripheral edge of the spray head tip surface while being accelerated, resulting in an extremely thin filamentous It is discharged as a paint stream. The filamentous paint flow is discharged from the outer peripheral edge of the spray head, and then this liquid thread is torn to form fine paint particles, so that coarse paint particles are not mixed in during paint spraying.

In the rotary atomizing electrostatic coating apparatus according to the second aspect of the present invention, the cup-shaped spray head is located outside the inner surface of the spray head and extends in the central axis direction of the spray head. Since the inflow end of the coating material into the coating material guide groove is opened on the protruding annular surface, it has basically the same function as the rotary atomizing electrostatic coating device according to the above-mentioned claim 1, and the annular surface has an inner peripheral surface. Since it is located outside of the extension of the surface, complicated processing such as projecting the inner peripheral surface of the spray head in an overhang shape is unnecessary.

As an embodiment of the rotary atomizing electrostatic coating apparatus according to claims 1 and 2 of the present invention, in the rotary atomizing electrostatic coating apparatus according to claim 3, the rising portion of the annular surface is a curved surface. Since the finishing is performed, the processing is easy, and the coating material is prevented from staying in the recessed portion, which facilitates cleaning when switching the coating material.

As an embodiment of the rotary atomizing electrostatic coating device according to claim 2 of the present invention, in the rotary atomizing electrostatic coating device according to claim 4, the inner peripheral surface of the spray head is changed to an annular surface. Since the corners up to the corners are finished as curved surfaces, the glittering material made of powder such as aluminum, pearl and mica mixed in the paint is not pressed against the corners and deformed.

Further, claim 1 and claim 2 of the present invention.
As an embodiment of the rotary atomizing electrostatic coating device according to the present invention, in the rotary atomizing electrostatic coating device according to claim 5, since the paint guide groove is V-shaped, for example, it is processed in comparison with a circular groove or a U-shaped groove. It will be easy to wear.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings.

1 to 3 are explanatory views showing the structure of a rotary atomizing electrostatic coating apparatus according to a first embodiment of the present invention, and FIGS. 1 (a) and 1 (b) show the rotary fog. Sectional view and partial front view of the spraying head portion of the electrostaticization electrostatic coating apparatus, FIG. 2 is a perspective view of the spraying head tip portion, and FIG. 3 is III-II of FIG.
It is an expanded sectional view in the I line position.

The rotary atomizing electrostatic coating apparatus 1 shown in the drawing comprises a rotary shaft 2 rotating at high speed, a cup-shaped spray head 3 fixed to the rotary shaft 2, and a paint supply nozzle 4, A paint receiver 5 is fixed inside the spray head 3 in front of the supply nozzle 4, and a large number of paint outflow holes 5a are provided around the outer peripheral edge of the paint receiver 5 over the entire circumference thereof.

Further, the spray head 3 is provided with an annular surface 3b extending from the position near the tip of the inner peripheral surface 3a in the direction of the central axis of the spray head 3, and the tip surface 3c of the spray head 3 is provided with a large number. The paint guide grooves 6 are formed radially.

As shown in FIG. 2 or 3, the paint guide groove 6 has a V-shape whose width and depth gradually decrease from the inner peripheral side to the outer peripheral side of the spray head tip surface 3c. hand,
The inner peripheral side thereof opens to the annular surface 3b and serves as an inflow end of the paint.

The rising angle θ of the annular surface 3b with respect to the inner peripheral surface 3a is set to 20 ° in this embodiment, but it is not particularly specified, and the diameter of the spray head 3 and the number of rotations are not limited. It can be appropriately set according to the centrifugal force generated by the above and the discharge amount of the paint.

Further, a high negative voltage is applied to the spray head 3 by a high voltage generator (not shown) so that the atomized paint particles are given a negative charge.

A rotary atomizing electrostatic coating device 1 having such a structure.
In, when the paint is sprayed from the paint supply nozzle 4 to the vicinity of the center of the paint receiver 5 of the spray head 3 which rotates at high speed together with the rotating shaft 2, the paint is curved by the centrifugal force due to the rotation of the spray head 3 to the curved surface 5b of the paint receiver 5. Through the paint outflow hole 5a to the inner peripheral surface 3a of the cup-shaped spray head 3.

Then, this paint spreads along the inner peripheral surface 3a to form a thin liquid film and flows from the inner peripheral surface 3a into the paint guide groove 6 formed in the spray head tip surface 3c.

FIG. 4 is a view from the direction of arrow IV in FIG. 3, and is a schematic view for explaining the flow of paint into the guide groove 6.

That is, when the paint flow F flowing as a thin liquid film along the inner peripheral surface 3a branches into the paint guide grooves 6 and flows in, it flows near the bottoms 6a of the respective guide grooves 6. For F, guide groove 6 at almost the same speed
It flows straight inward. On the other hand, the inflow end (inlet) of the paint into the paint guide groove 6 rises at a predetermined angle (20 ° in this embodiment) with respect to the inner peripheral surface 3a.
Since the paint flow F that has flowed toward the boundary P with the adjacent guide groove 6 is suppressed by the annular surface 3b, it spreads in the circumferential direction along the annular surface 3b. Since the flow is about to flow, it does not go over the boundary portion P between the guide grooves 6 and changes its direction as shown by the arrow in the figure, and flows into the paint guide groove 6.

The paint flowing into the paint guide groove 6 is guided to the outer peripheral edge of the spray head tip surface 3c while being accelerated in the guide groove 6 by a strong centrifugal force and reducing the thickness, and an extremely thin liquid is applied from the outer peripheral edge. After being discharged in the form of threads, the liquid threads are torn to form extremely fine paint particles m, which are applied to the object to be coated, so that a uniform and even coating film is formed.
The coating quality can be improved.

FIGS. 5 (a), 5 (b) and 5 (c) are a partial front view, an enlarged sectional view and a spray head of a spray head showing a second embodiment of the rotary atomizing electrostatic coating apparatus according to the present invention. It is a perspective view of a front-end | tip part.

That is, in this embodiment, the annular surface 3b is formed by partially scraping off the tip of the inner peripheral surface 3a of the spray head 3, and the same operational effect as in the first embodiment. In addition, since the inner peripheral surface 3a of the spray head 3 is machined so as to be machined, the machining is easier than that of the first embodiment.

In each of the above embodiments, the paint guide groove 6 is formed in a V shape, but in the rotary atomizing electrostatic coating apparatus according to the present invention, the shape of the paint guide groove is shown. Is not particularly limited, and for example, a circular groove or a U-shaped groove can be adopted.

6 (a), 6 (b) and 6 (c) show another example of the shape of the spray head of the rotary atomizing electrostatic coating apparatus according to the present invention.

That is, FIGS. 6 (a) and 6 (b) show an example in which the rising portion of the annular surface 3b is finished into a curved surface, and by adopting such a shape, it becomes easier to process. Further, it is possible to prevent the paint from staying in the recessed portion, and it becomes easy to clean when switching the paint.

Further, FIG. 6 (c) shows an example in which the corners from the inner peripheral surface 3a of the spray head to the annular surface 3b are finished into curved surfaces, by which the luster material ( For example, powder of aluminum, pearl, mica, etc.) can be prevented from being pressed and deformed at the corners.

[0035]

As described above, according to the first aspect of the present invention.
In the rotary atomizing electrostatic coating apparatus according to 1, the spray head has an annular surface extending from the inner peripheral surface in the central axis direction of the spray head, and the inflow end of the paint into the paint guide groove is provided on the annular surface. Since it is configured to open, when the paint flow flows from the inner peripheral surface of the spray head into the paint guide groove, the paint flow that tries to get over the boundary between the guide grooves is circled along the annular surface. Since it is possible to change in the circumferential direction and all the paint can be made to flow into the paint guide groove, it is possible to prevent the generation of coarse paint particles and significantly improve the paint quality. Very good effect.

Further, in the rotary atomizing electrostatic coating apparatus according to the second aspect of the present invention, the cup-shaped spray head is located outside the inner surface of the spray head and extends in the direction of the central axis of the spray head. Since the inflow end of the paint into the paint guide groove is opened in the annular surface extending to the above, the above-mentioned claim 1
Not only can the same effect as the rotary atomizing electrostatic coating device related to the above can be obtained, but complicated processing such as protruding the inner peripheral surface of the spray head in the form of an overhang is not required, so processing becomes easy. The effect is that material and processing costs can be reduced.

As an embodiment of the rotary atomizing electrostatic coating apparatus according to the present invention, in the rotary atomizing electrostatic coating apparatus according to claim 3, the rising portion of the annular surface is finished into a curved surface. Further, it is possible to easily process, and it is possible to prevent the paint from accumulating in the recessed portion and facilitate cleaning when switching the paint. As an embodiment of the rotary atomizing electrostatic coating device according to claim 2 of the present invention, in the rotary atomizing electrostatic coating device according to claim 4, a corner portion from the inner peripheral surface of the spray head to the annular surface is provided. Since it is designed to have a curved surface, it is possible to effectively prevent deformation caused by the glitter material in the paint being pressed against the corners.

Further, as an embodiment of the rotary atomizing electrostatic coating device according to the present invention, in the rotary atomizing electrostatic coating device according to claim 5, since the paint guide groove is V-shaped, for example, a circular groove. As compared with the U-shaped groove or the U-shaped groove, it is possible to facilitate the processing.

[Brief description of drawings]

FIG. 1A is a vertical cross-sectional explanatory view of a spray head portion according to a first embodiment of a rotary atomizing electrostatic coating apparatus according to the present invention. (B) It is a partial front explanatory view of the spray head of the rotary atomizing electrostatic coating apparatus shown in FIG. 1 (a).

FIG. 2 is a perspective explanatory view showing the shape of the tip of the spray head shown in FIG. 1 (b).

FIG. 3 is an enlarged cross-sectional explanatory view taken along the line III-III in FIG. 1 (b).

4 is an explanatory view showing an atomizing mechanism by the rotary atomizing electrostatic coating apparatus shown in FIG. 1, and is a view seen from an arrow IV direction in FIG.

FIG. 5 (a) is a partial front view of the spray head according to the second embodiment of the rotary atomizing electrostatic coating device of the present invention. (B) It is an expanded sectional explanatory view in the Vb-Vb line position of Drawing 5 (a). FIG. 6C is a perspective explanatory view showing the shape of the tip of the spray head shown in FIG.

6 (a), (b) and (c) are enlarged cross-sectional explanatory views of the tip of the spray head showing another example of the shape of the spray head of the rotary atomizing electrostatic coating apparatus according to the present invention.

FIG. 7A is a cross-sectional view showing a conventional rotary atomizing electrostatic coating device. (B) It is explanatory drawing which shows the atomization mechanism by the rotary atomization electrostatic coating device shown to Fig.7 (a), and is an arrow line view from the arrow B direction of Fig.7 (a).

[Explanation of symbols]

 1 Rotating Atomizing Electrostatic Coating Device 3 Spray Head 3a Inner Surface 3b Annular Surface 3c Tip Surface 6 Paint Guide Groove

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shuji Torii 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd.

Claims (5)

[Claims] 1. A rotary atomizing electrostatic coating apparatus for atomizing paint supplied to the inner peripheral surface of a rotating cup-shaped spray head from the peripheral edge of the spray head tip surface, wherein the spray head has an outer periphery. A plurality of paint guide grooves having a width and a depth gradually decreasing toward the side are provided in the radial direction, and an annular surface extending from the inner peripheral surface in the central axis direction of the spray head is provided, and the annular surface is provided with the above-mentioned annular surface. A rotary atomizing electrostatic coating device, characterized in that the paint inflow end into the paint guide groove is open. 2. A rotary atomizing electrostatic coating apparatus for atomizing paint supplied to the inner peripheral surface of a rotating cup-shaped spray head from the peripheral edge of the spray head tip surface, wherein the spray head has an outer periphery. A plurality of paint guide grooves whose width and depth are gradually reduced toward the side are provided in the radial direction, and the paint guide grooves are located outside the surface extending the inner peripheral surface and extend in the central axis direction of the spray head. A rotary atomizing electrostatic coating device having an annular surface, and an inflow end of the coating material into the coating material guide groove is opened in the annular surface. 3. The rotary atomizing electrostatic coating device according to claim 1 or 2, wherein the rising portion of the annular surface is curved. 4. The rotary atomizing electrostatic coating device according to claim 2, wherein the corner portion from the inner peripheral surface to the annular surface is finished with a curved surface. 5. The rotary atomizing electrostatic coating device according to claim 1, wherein the paint guide groove is V-shaped.