JP2014233650A - Coating head and coating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating head and a coating device capable of reducing adhered coating.SOLUTION: In a coating head 10 having a plurality of nozzles 12 where tip parts 12a are projected from a head body 11, a nozzle 12 has a capillary for a coating flow passage surrounding the coating flow passage and a capillary for an atomization air flow passage surrounding the atomization air flow passage and being disposed at the outer periphery of the capillary for the coating flow passage. A distance L from the head body 11 to the tip part 12a of the nozzle 12 is 11.8 mm or more. A coating device includes the coating head 10.

Description

  The present invention relates to a coating head and a coating apparatus.

  In general, the coating efficiency of spray coating is very low compared with brushes or roller coating, and is usually about 50 to 60%. In order to improve the coating efficiency, it is necessary to reduce the spray pattern as much as possible to increase the inertial force of the atomized paint particles in the direction of the object to be coated. It is. In other words, if spray coating is performed while moving the spray gun at a coating distance of several centimeters, it is possible to make the atomized paint particles collide with the object to be coated at a high coating speed. It is also possible to ensure 90% or more.

  However, when the spray distance is reduced in this way, the spray pattern width becomes extremely small. In order to make the wet coating film sprayed by one spray gun movement operation moderately thin, it is necessary to reduce the discharge amount. For this reason, a multi-nozzle type coating head having a plurality of nozzles may be used (for example, see Patent Document 1).

JP 2000-167446 A

  However, in the conventional coating head, there is a problem that the paint that has rebounded from the paint surface tends to adhere to the tip of the nozzle including the periphery of the atomizing air injection port, and this attached paint is difficult to remove with a cleaning device. When the adhering paint accumulates around the atomizing air injection port, the atomizing air jet flow is disturbed, and the paint and atomizing air balance of other nozzles is broken, resulting in disturbance of the coating pattern. If the coating pattern is disturbed, the coating film thickness becomes non-uniform and the predetermined performance cannot be ensured.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the coating head and coating device which can reduce adhesion paint.

  In order to solve the above-described problems, the present invention provides a coating head having a plurality of nozzles with tip portions protruding from the head body, the nozzles being a paint channel narrow tube surrounding the paint channel, and the paint channel And an atomizing air passage narrow tube surrounding the atomizing air passage provided on the outer periphery of the thin tube, and the distance from the head body to the tip of the nozzle is 11.8 mm or more Provide the head.

  It is preferable to have a contact structure in which the fine tube for the paint channel and the narrow tube for the atomized air channel are in contact with each other in the middle of the atomized air channel.

  In the contact structure, it is preferable that the paint channel narrow tube and the atomizing air channel narrow tube are in contact with each other at three or more locations in the circumferential direction of the paint channel narrow tube.

  Moreover, this invention provides the coating device which has the said coating head.

According to the present invention, by extending the protruding length of the nozzle, a space for air to flow in from the surroundings is obtained between the painted surface and the head body, so that the paint adheres around the atomizing air injection port. Can be suppressed.
Further, by providing a contact structure in the middle of the atomizing air flow path, it is possible to suppress the bending of the nozzle even if the protruding length of the nozzle is increased.

It is a conceptual diagram which shows an example of the use condition of the coating head of this invention. It is (a) front view and (b) end view which show an example of the nozzle used for the coating head of this invention. (A) is sectional drawing which follows the AA line of FIG.2 (b), (b) is sectional drawing which follows the BB line of FIG.2 (b). (A) is sectional drawing which follows the CC line of Fig.2 (a), (b) is sectional drawing which follows the DD line | wire of Fig.2 (a).

The present invention will be described below based on preferred embodiments with reference to the drawings.
In FIG. 1, an example of the use condition of the coating head of this invention is shown. The coating head 10 has a plurality of nozzles 12 with tips 12a protruding from the head body 11. In the illustrated example, a plurality of nozzles 12 are arranged in two rows on the front surface 11 a of the head body 11. For example, each row has about eight nozzles in a direction perpendicular to the paper surface of FIG. 1, but is not particularly limited thereto.

  The coating head 10 includes, for example, a single paint supply port that connects a flow path of a paint supply system that supplies paint to the nozzle 12 to the head body 11, and an atomization air supply system that supplies atomization air to the nozzle 12. For example, it has a single atomizing air supply port for connecting the flow paths. In the head body 11, a paint supply branch flow path is formed which branches from the paint supply port to a plurality of nozzles and reaches the paint flow path 13 of each nozzle 12, and branches from the atomizing air supply port to the plurality of nozzles. Thus, an atomizing air supply branch channel that reaches the atomizing air channel 15 of each nozzle 12 is formed. Note that the number and arrangement of the nozzles 12 provided in the coating head 10 can be variously selected.

  As shown in FIGS. 2 to 4, each nozzle 12 has a configuration in which an atomizing air flow path 15 is arranged in parallel on the outer periphery of the paint flow path 13. As shown in FIG. 3, an atomizing air injection port 15 a that is a front end opening of the atomizing air flow channel 15 is disposed around a paint injection port 13 a that is the front end opening of the coating material flow channel 13.

The paint supply system feeds the paint from the paint tank toward the paint flow path 13 of each nozzle 12 using a pump or the like. The atomizing air supply system supplies atomizing air (compressed air) from the compressor or the like toward the atomizing air flow path 15 of each nozzle 12.
Each nozzle 12 is supplied with the paint to the paint flow path 13 and is supplied with the atomized air (compressed air) to the atomizing air flow path 15, so that the paint sprayed from the paint injection port 13 a is atomized air. It atomizes and atomizes with the atomization air injected from the injection port 15a. The sprayed paint particles are sprayed onto the coating surface 1 as shown in FIG. 1 while forming, for example, a conical spray pattern in the spray direction of each nozzle 12.

  The flow of the paint 2 ejected from the nozzle 12 proceeds toward the painted surface 1, and most of the paint particles adhere to the painted surface 1. However, some of the paint is contained in the flow of the atomized air that transports the paint particles reflected back to the paint surface 1. When the sprayed paint flows from the painting head 10 toward the painting surface 1 between the painting surface 1 and the front surface 11 a of the head body 11, a negative pressure region whose atmospheric pressure is lower than the surroundings is formed on the front surface 11 a of the head body 11. Arise. If the air flowing into the negative pressure region is atomized air containing paint that is reflected back from the paint surface 1, a large amount of paint may adhere to the head main body 11, the tip 12a of the nozzle 12, or the like. is there.

  As described above, when the adhering paint accumulates around the atomizing air injection port, the jet flow of the atomizing air is disturbed, and the balance between the paint of the other nozzles and the atomizing air is disturbed, and the paint pattern is disturbed. Occurs. If the coating pattern is disturbed, the coating film thickness becomes non-uniform and the predetermined performance cannot be ensured.

  In the case of the coating nozzle of this embodiment, the length that the nozzle 12 protrudes from the head body 11, that is, the distance (nozzle protruding length) L from the front surface 11 a of the head body 11 to the tip 12 a of the nozzle 12 is 11.8 mm. That's it. As a result, the distance between the head main body 11 and the coating surface 1 also increases, and the paint sprayed from the nozzle 12 flows from the coating head 10 toward the coating surface 1 as shown in FIG. A space into which the outside air 3 flows from the periphery toward the negative pressure region on the front surface 11a is obtained. Thereby, it can suppress that a coating material adheres to the front-end | tip part 12a of the head main body 11 or the nozzle 12, especially the surroundings of the coating material injection port 13a or the atomization air injection port 15a. The protruding length L of the nozzle may be, for example, 11.8 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, or the like.

  2 to 4 show the detailed structure of the nozzle. 2A is a front view of the nozzle, and FIG. 2B is an end view of the nozzle as viewed from the tip side. 3A is a sectional view taken along line AA in FIG. 2B, FIG. 3B is a sectional view taken along line BB in FIG. 2B, and FIG. 4A is FIG. FIG. 4A is a cross-sectional view taken along the line CC of FIG. 4A, and FIG. 4B is a cross-sectional view taken along the line DD of FIG. 3 (a) and 4 (a) are cross-sectional views showing a portion including a contact structure 17 described later, and FIGS. 3 (b) and 4 (b) are cross-sectional views showing a portion not including the contact structure. is there.

  The nozzle 12 includes a paint flow channel narrow tube 14 surrounding the paint flow channel 13 and an atomization air flow channel narrow tube 16 surrounding an atomization air flow channel 15 provided on the outer periphery of the paint flow channel narrow tube 14. The tip end portion 14a of the paint flow channel narrow tube 14 is inserted into the tip end portion 16a of the atomizing air channel narrow tube 16 in a non-contact state through a gap that can secure the atomizing air injection port 15a.

  The base end portion 12 b of the nozzle 12 is formed with a paint introduction port 13 b through which paint is introduced into the paint flow path 13. A taper portion 13t in which the cross-sectional area of the paint flow channel 13 decreases toward the tip side is formed between the paint introduction port 13b on the base end side and the paint injection port 13a on the tip end side. On the tip side of the taper portion 13t, the paint flow path 13 is substantially linear with the same inner diameter.

A flange portion 12 f is formed at an intermediate portion in the longitudinal direction of the nozzle 12. The flange portion 12f is configured to fit a convex portion 14b formed on the flange portion 14f protruding from the outer periphery of the paint flow passage thin tube 14 to the proximal end portion 16b of the atomizing air flow passage thin tube 16. Is formed.
An atomizing air introduction port 15 b through which atomizing air is introduced into the atomizing air channel 15 is formed in the flange portion 12 f of the nozzle 12 (specifically, the flange portion 14 f of the paint channel thin tube 14). Between the proximal-side atomizing air introduction port 15b and the distal-side atomizing air injection port 15a, a tapered portion 15t is formed in which the cross-sectional area of the atomizing air channel 15 decreases toward the distal-end side. .

  The flange portion 12 f serves to prevent the nozzle 12 from coming off when the base end portion 12 b of the nozzle 12 is disposed in the head main body 11, and the front end surface of the flange portion 12 f constitutes the front surface 11 a of the head main body 11. Abuts against the back of the wall. Therefore, the range of the part which protrudes from the front surface 11a of the head main body 11 among the nozzles 12 exists in the front end side rather than the flange part 12f.

  In the middle of the atomizing air channel 15, a contact structure 17 in which the paint channel thin tube 14 and the atomizing air channel narrow tube 16 are in contact with each other is provided. In the contact structure 17, the paint flow passage thin tube 14 and the atomization air flow passage thin tube 16 are partly disposed on the outer periphery of the paint flow passage thin tube 14 (or the inner periphery of the atomization air flow passage thin tube 16). And are in contact. Before and after the contact structure 17, a gap serving as the atomizing air channel 15 is formed between the coating channel thin tube 14 and the atomizing air channel narrow tube 16 over the entire outer periphery of the coating channel thin tube 14. ing.

  In the present embodiment, the outer periphery of the paint channel thin tube 14 is partially in the middle of the paint channel thin tube 14 (the range indicated by the symbol S in FIG. 3A) as shown in FIG. 4A. Are provided with projecting portions 17a, 17a,... Having an arc shape similar to the inner diameter of the atomizing air flow passage narrow tube 16. The space between the adjacent protrusions 17a, 17a is substantially rectangular. That is, in the contact structure 17, the paint flow passage thin tubes 14 and the atomizing air flow passage thin tubes 16 are in contact with each other at four protrusions 17 a in the circumferential direction of the paint flow passage thin tubes 14. The outer diameter of the paint channel thin tube 14 in the contact structure 17 takes the maximum outer diameter on the projecting portion 17a, and the minimum outer diameter (the distance between opposite sides in a substantially rectangular outer shape) at the portion in contact with the atomizing air channel 15. Take.

In the case of this embodiment, the contact structure 17 starts from a position where the inner diameter is minimum at the tapered portion 15t of the atomizing air flow path 15 and has a length of about several mm. As shown in FIG. 4B, on the tip 12a side from the contact structure 17, the atomizing air flow path 15 has a uniform annular cross section with a narrow width of about 0.1 to 0.3 mm. By forming the atomizing air channel 15 on the tip side from the contact structure 17 over the entire outer periphery of the paint channel thin tube 14, the atomizing air ejected from the tip can be made uniform.
The width of the atomizing air flow path 15 on the distal end portion 12a side from the contact structure 17 (half the difference between the inner diameter of the atomizing air flow path thin tube 16 and the outer diameter of the paint flow path thin tube 14) is The width of the atomizing air channel 15 (half the difference between the inner diameter of the atomizing air channel narrow tube 16 and the minimum outer diameter of the paint channel narrow tube 14) may be set equal. Alternatively, in order to suppress the reduction in the cross-sectional area of the atomizing air flow path 15 in the contact structure 17, even if the radial flow path dimension is made larger because the circumferential flow path dimension is narrowed by the protrusion 17 a. Good.

On the base end side (the side with the flange portion 12 f) from the contact structure 17, the outer surface of the paint channel thin tube 14 may have a quadrangular cross-sectional shape with a rounded apex, as in the contact structure 17. Since the cross section of the atomizing air passage 15 is expanded by the tapered portion 15t, the paint passage thin tube 14 and the atomizing air passage thin tube 16 are not in contact with each other on the proximal side from the contact structure 17. . By forming the atomizing air flow path 15 on the base end side from the contact structure 17 over the entire outer periphery of the paint flow path thin tube 14, variations in atomizing air introduced from the atomizing air introduction port 15 b are suppressed. be able to.
In addition, in the flange portion 12f of the nozzle 12, a part (the flange portion 14f, the convex portion 14b, and the base end portion 16b) of the paint channel thin tube 14 and the atomizing air channel narrow tube 16 are in contact with each other. In this portion, the gap is closed over the entire circumference, and the atomizing air flow path 15 is not formed.

  When the contact structure 17 is not provided, the paint flow passage thin tube 14 and the atomizing air flow passage thin tube 16 are atomized from the proximal flange portion 12f (the flange portion 14f and the convex portion 14b of the paint flow passage thin tube 14). Only the base end portion 16b) of the air flow narrow tube 16 is in contact, and the paint flow channel thin tube 14 and the atomizing air flow narrow tube 16 are not in contact with each other on the distal end side. In the case of such a structure, as described above, when the protruding length L of the nozzle 12 is increased, the length from the flange portion 14f to the tip end portion 14a of the paint channel thin tube 14 is also increased. Since the tip end portion 14a of the paint flow channel narrow tube 14 protrudes in a cantilevered manner, even if it is slightly bent, the tip end portion 14a comes into contact with the inner surface of the atomization air flow channel narrow tube 16 to cause the atomization air channel 15 It will block a part of. in this case. There is a possibility that the spray of atomized air becomes non-uniform in the circumferential direction around the paint ejected from the paint spraying port 13a, so that a properly atomized paint cannot be obtained.

  On the other hand, when the contact structure 17 is provided in the middle of the flow path, it is possible to suppress the bending of the paint flow path thin tube 14 (particularly the portion closer to the tip end portion 14a than the flange portion 14f). Thereby, the nozzle 12 with the uniform cross section of the atomization air flow path 15 can be easily produced even if the protrusion length L is long, without increasing the number of parts of the nozzle 12.

  The length of the paint flow passage narrow tube 14 (particularly the portion closer to the tip end portion 14a than the flange portion 14f) surrounded by the atomization air flow passage narrow tube 16 is the length a of the atomization air flow passage (not shown). ), That is, approximately equal to the length (the length from the base end portion 16 b to the tip end portion 16 a) of the atomizing air flow path narrow tube 16. If the angle at which the distal end portion 14a of the paint channel thin tube 14 is bent from the flange portion 14f is α (not shown), the opening width b of the atomizing air injection port 15a with respect to the length a of the atomizing air channel 15 (see FIG. If b / a is equal to tan α, the tip end portion 14a of the paint flow channel narrow tube 14 comes into contact with the tip end portion 16a of the atomizing air flow channel narrow tube 16. The opening width of the atomizing air injection port 15a is the radial width of a substantially cylindrical thin tube.

Therefore, when the length of the atomizing air flow path 15 is a and the opening width of the atomizing air flow path 15 at the tip end portion 12a of the nozzle 12 is b, an angle θ that satisfies θ = tan ⁻¹ (b / a). Is smaller than the angle α at which the distal end portion 14a bends, it is possible to prevent contact between the distal end portions 14a and 16a of the thin tube. If the angle α at which the distal end portion 14a bends is about 1 °, an angle θ that satisfies θ = tan ⁻¹ (b / a) (because b> 0, θ is greater than 0 °). Preferably it is less than 1 °.

As mentioned above, although this invention has been demonstrated based on the suitable form example, this invention is not limited to the above-mentioned form example, A various change is possible in the range which does not deviate from the summary of this invention.
Examples of the members constituting the nozzle include metals such as stainless steel and tinplate from the viewpoint of durability against water, organic solvents, etc., detergency, and mechanical strength.

  The shape of the cross section (cross section perpendicular to the nozzle longitudinal direction) of the nozzle 12, the paint flow path 13, the fine paint flow path tube 14, the atomization air flow path 15 and the atomization air flow path narrow tube 16 is the above-described embodiment. Then, although it is circular as shown in FIG. 4, it may be a polygon such as a triangle, a quadrangle, a hexagon, an octagon, or an ellipse. The polygon may be a shape that is rounded by an arc or the like in the vicinity of the vertex. In the contact structure 17, the number of contact points between the paint channel narrow tube 14 and the atomizing air channel narrow tube 16 can be two opposing points or three or more in the circumferential direction. More than that is more preferable.

In FIG. 1, the orientation of the painted surface 1 is a vertical surface, but the present invention can also be applied when the painted surface is a horizontal surface or an inclined surface. The direction in which the paint is sprayed from the painting head onto the painting surface is arbitrary, such as laterally, upwardly, downwardly, and obliquely.
The present invention can also be applied to various structures such as automobiles and machines, or coating on large structures such as bridges, gas tanks, buildings, and ships.

  Hereinafter, the present invention will be described in detail by comparing a comparative example and an example.

(Comparative Example 1)
It has a nozzle with a distance (projection length) from the head body to the tip of the nozzle of 1.8 mm, and the length of the portion surrounded by the fine tube for the paint flow channel is 6 mm, and the contact structure A coating head of Comparative Example 1 was prepared without having any. The opening width of the atomizing air channel is about 0.15 mm, and the minimum bending angle α at which the tip of the paint channel narrow tube contacts the tip of the atomizing air channel narrow tube is tan ⁻¹ (0 .15 / 6) is about 1.43 °.
Using a coating apparatus having the coating head of Comparative Example 1, an area of 5 m ² was coated at a discharge rate of 420 g / min. At this time, the total amount of paint discharged is 1165 g (814 g in terms of solid content). The ratio of the amount of paint adhered to the head body 11 with respect to the total amount of paint discharged was about 0.020%.

Example 1
The distance (projection length) L from the head body 11 to the tip 12a of the nozzle 12 is 11.8 mm, the length a of the portion surrounded by the fine tube for paint flow passage 14 by the fine tube for atomization air passage 16 is 16 mm, and contact The coating head 10 of Example 1 having the nozzle 12 with the length of the structure 17 (reference S in FIG. 3A) being 2 mm was produced. The opening width b of the atomizing air flow path 15 is about 0.15 mm, and when the contact structure 17 is not present, the tip end portion 14a of the paint flow path narrow tube 14 contacts the tip end portion 16a of the atomizing air flow path narrow tube 16. The minimum bending angle α is about 0.54 ° according to tan ⁻¹ (0.15 / 16).
Using the coating apparatus having the coating head of Example 1, an area of 5 m ² was coated at a discharge rate of 420 g / min. At this time, the total amount of paint discharged is 1165 g (814 g in terms of solid content). The ratio of the amount of paint adhered to the head body 11 with respect to the total amount of paint discharged was about 0.0035%.

  According to the first embodiment, the tip end portion 14a of the paint flow channel thin tube 14 contacts the tip end portion 16a of the atomizing air flow channel narrow tube 16 only by bending the tip end portion 14a of the paint flow channel narrow tube 14 by about 1 °. Even if the nozzle is long enough, it is possible to prevent the bending by having the contact structure 17, and it is possible to produce the nozzle 12 having the substantially uniform annular atomizing air injection port 15a. In addition, the amount of paint adhered was reduced to about 1/6 compared to Comparative Example 1.

DESCRIPTION OF SYMBOLS 1 ... Paint surface, 2 ... Paint, 3 ... Outside air, 10 ... Paint head, 11 ... Head main body, 12 ... Nozzle, 13 ... Paint flow path, 14 ... Fine tube for paint flow path, 15 ... Atomization air flow path, 16 ... fine tube for atomizing air flow path, 17 ... contact structure.

Claims (4)

A coating head having a plurality of nozzles with tips protruding from the head body,
The nozzle has a paint channel narrow tube surrounding the paint channel, and an atomizing air channel narrow tube surrounding the atomizing air channel provided on the outer periphery of the paint channel narrow tube,
The coating head, wherein a distance from the head body to the tip of the nozzle is 11.8 mm or more.   2. The coating head according to claim 1, wherein the coating head has a contact structure in which the fine tube for the paint flow channel and the narrow tube for the atomized air flow channel are in contact with each other in the middle of the atomizing air flow channel.   3. The contact structure according to claim 2, wherein the paint channel narrow tube and the atomizing air channel narrow tube are in contact with each other at three or more locations in the circumferential direction of the paint channel narrow tube. The painting head described.   The coating apparatus which has a coating head of any one of Claims 1-3.

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