JP2013017933A - Coating spray gun - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spray gun having a nozzle air hole of a new structure capable of preventing biased airflow in an annular passage formed between an air cap and a nozzle by improving the nozzle air hole itself.SOLUTION: The nozzle 13 disposed in the rear of the air cap 15 in the spray gun includes a cylinder part 31, and a flange 32 formed extending in the outer peripheral direction thereof. In the nozzle air hole 36 provided to the flange 32, an opening of an outflow port 40 at a tip end face of the flange 32 is formed larger than an opening of an inflow port 39 at a base end face of the flange 32.

Description

The present invention relates to an improvement of a spray gun for painting, particularly a low-pressure spray gun.

In general, a spray gun for painting is provided with an air cap and a nozzle disposed behind the air cap at the tip, thereby spraying paint in a mist form. Specifically, the nozzle body includes a cylindrical portion having a central hole through which the paint passes from the proximal end side to the distal end side, and a flange formed so as to protrude in the outer peripheral direction of the cylindrical portion. The flange includes a nozzle air hole through which air for discharging the paint flows out from the proximal end surface of the flange to the distal end surface. The air cap attached to the tip side of the nozzle includes a paint discharge hole and an atomizing air hole formed around the paint discharge hole, and a pair of corners usually protrude from the tip. The corners are provided with pattern air holes for discharging air for pattern formation. The atomizing air hole and the nozzle air hole are connected via an annular passage formed between the air cap and the nozzle, and the air blown out of the paint from the paint discharging hole is ejected from the atomizing air hole. In order to form a fan-like flat pattern, the air is sprayed out and atomized to be sprayed, and the air jetted from the pattern air holes is collided.

In the normal spray gun in which the internal pressure of the air cap exceeds 150 kPa, the atomization efficiency is good, but the disadvantages are that the sprayed paint particles are scattered and the paint loss due to overspray is large. . Therefore, in recent years, low-pressure spray guns that spray with low-pressure compressed air whose air cap has an internal pressure of 100 kPa or less have been widely used. However, if the pressure of air is suppressed, a partial defect in the fineness of the paint particles or a deviation in the pattern shape occurs due to the deviation of the airflow in the annular passage formed between the air cap and the nozzle. The problem occurs.

For this reason, in Patent Documents 1 and 2, a shielding plate is arranged in front of the outlet of the nozzle air hole, and the air from the nozzle air hole is caused to collide with the shielding plate, thereby causing a bias in the annular passage. Propose to prevent. In these inventions, the structure of the conventional high-pressure spray gun is used as it is for the nozzle air holes, and the problem is solved by the collision of compressed air at the tip side of the nozzle air holes. It was.

Japanese Patent No. 2693402 JP 2006-247538 A

The present invention provides a spray gun having a nozzle air hole with a new structure that can improve the nozzle air hole itself and prevent the airflow in the annular passage formed between the air cap and the nozzle. With the goal.

The present invention is
An air cap and a nozzle disposed behind the air cap;
The nozzle includes a cylindrical portion having a central hole through which the paint passes from the proximal end side to the distal end side, and a flange formed so as to protrude in the outer peripheral direction of the cylindrical portion,
The flange includes a nozzle air hole that causes air for discharging the paint to flow out from the proximal end surface of the flange to the distal end surface;
The front air cap includes a paint discharge hole and an atomizing air hole formed around the paint discharge hole,
The atomizing air hole and the nozzle air hole are connected via an annular passage formed between the air cap and the nozzle, and the paint from the paint discharge hole is discharged from the atomizing air hole. In the spray gun for painting that is atomized by the air
The nozzle air hole provides a spray gun for coating, wherein an opening of an outlet on the distal end surface of the flange is formed larger than an opening of an inlet on the proximal end surface of the flange. .

The present invention is a new structure in which the nozzle air hole is changed in the middle of the hole to form the outlet opening larger than the inlet opening instead of the conventional structure in which the nozzle air hole remains constant. By providing the above, it was possible to prevent poor paint particle miniaturization and uneven pattern shape and to achieve good paint spraying.

Specifically, in the present invention, the compressed air that enters the nozzle air hole from the narrow inlet port spreads when it flows out from the large outlet port, thereby mitigating the bias of the air flow in the annular passage. It is believed that there is.
As a result, good paint spraying in the low-pressure spray gun can be realized without providing a shielding plate in front of the outlet of the nozzle air hole.

In addition, since the present invention improves the structure of the nozzle air hole itself, it can be used in combination with a conventional shielding plate, thereby further homogenizing the air in the annular passage. it can.
The present invention can also be used in a normal spray gun in which the internal pressure of the air cap exceeds 150 kPa.

It is sectional drawing of the spray gun which concerns on embodiment of this invention. It is an expanded sectional view of the atomization apparatus of the spray gun. (A) is a principal part enlarged view of the atomizer, (B)-(E) is a principal part enlarged view which shows a modification, respectively. It is an expanded sectional view of the atomization device of the spray gun concerning other embodiments of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A spray gun according to an embodiment of the present invention includes a spray gun main body 11 and an atomizing device 12 disposed at the tip thereof. The atomization device 12 includes a nozzle 13, a needle valve 14, and an air cap 15. The nozzle 13 includes a cylindrical portion 31 and a flange 32 that projects outward from the diameter of the cylindrical portion 31.

The spray gun body 11 is formed with a compressed air introduction path 16 and a paint supply path 17. The compressed air introduction path 16 is connected to the branch path 18, and the branch path 18 distributes air to the inner path 19 and the outer path 20. The air distributed to the inner path 19 becomes atomizing air, and the air distributed to the outer path 20 becomes pattern forming air.

The coating material supply path 17 supplies the coating material to the cylindrical portion 31 of the nozzle 13, and the coating material flows out from the coating material ejection port 35 at the tip through a central hole 34 that penetrates the central portion of the nozzle 13.

A male screw 33 is formed at the base end of the nozzle 13 and is screwed into the tip recess of the spray gun body 11 to connect the paint supply path 17 and the base end of the central hole 34 of the nozzle 13 in a liquid-tight manner. .

As described above, the paint nozzle 35 is provided at the tip of the central hole 34 of the nozzle 13, and the needle valve 14 is disposed in the central hole 34 so as to be movable back and forth. The paint flowing in from the base end of the central hole 34 is ejected from the paint jet outlet 35 through the central hole 34. The needle valve 14 moves back and forth, thereby adjusting the opening of the valve and adjusting the amount of paint sprayed. Although the nozzle 13 is integrally formed, the nozzle tip at the tip portion provided with the paint spout 35 may be formed separately from the nozzle body.

With the nozzle 13 incorporated in the spray gun body 11, the flange 32 partitions the inner path 19 and the outer path 20 with a seat portion. Air from the outer path 20 bypasses the outer periphery of the nozzle 13 and is jetted from the pattern air hole 54 of the air cap 15. The pattern air holes 54 are formed in a pair of corner portions 55 formed so as to protrude from the tip of the air cap 15, and jet pattern forming air.

Air from the inner passage 19 passes through the nozzle air holes 36 penetrating the front and rear of the flange 32 of the nozzle 13 and is ejected from the air holes 51 of the air cap 15. In this example, the air holes 51 include a main air hole 52 formed in an annular shape on the outer peripheral side of the paint jet nozzle 35 of the nozzle 13, and a plurality of auxiliary air holes 53 formed on the outer side of the main air hole 52. With.

The nozzle air hole 36 will be described in more detail. Two or more nozzle air holes 36 are normally provided on the circumference (six in this example). From the inlet 39 formed on the proximal end surface 37 of the flange 32, the nozzle air hole 36 is formed on the distal end surface 38. Connect to the outlet 40. The nozzle air hole 36 in the figure is formed in parallel with the axial direction of the central hole 34, but may be formed obliquely at an angle. The inflow port 39 opens to the inner passage 19 described above, and the outflow port 40 opens to the annular passage 21. The annular passage 21 is a space between the front end surface 38 of the nozzle 13 and the rear end surface 56 of the central portion of the air cap 15. Air is rectified by this space and is ejected from the main air hole 52. In a normal spray gun in which the internal pressure of the air cap 15 exceeds 150 kPa, it can be uniformly rectified by a conventional general structure and a good injection pattern can be obtained. However, in a low pressure spray gun of 100 kPa or less, In some cases, the airflow in the passage 21 is unevenly distributed, making it difficult to obtain a good injection pattern. Therefore, in the present invention, the opening of the outlet 40 of the nozzle air hole 36 is formed larger than the opening of the inlet 39 as shown in FIGS. Thus, the compressed air that has flowed into the nozzle air hole 36 from the narrow inlet 39 flows out into the annular passage 21 through the wide outlet 40. Due to the diffusion effect of the air flow at the time of the outflow, even if the compressed air has a low pressure, the uneven distribution of the air flow in the annular passage 21 can be suppressed, and a good atomized state can be obtained.

In the example shown in FIG. 3A, the nozzle air hole 36 is formed by forming a large diameter portion 41 on the distal end side and a small diameter portion 42 on the proximal end side through a stepped portion 43. The sectional area b of the outlet 40 is not particularly limited, but is preferably about 2 to 25 times the sectional area a of the inlet 39. The axial length c of the small diameter portion 42 is not particularly limited, but is preferably about 3 to 70% of the axial length d of the large diameter portion 41.

If the sectional area b of the outlet 40 is larger than 25 times the sectional area a of the inlet 39, the sectional area a of the inlet 39 becomes relatively small, and there is a possibility that a sufficient amount of air cannot be obtained. On the contrary, when the cross-sectional area b of the outlet 40 is smaller than twice the cross-sectional area a of the inlet 39, the size of the inlet / outlet does not change so much and a sufficient effect cannot be obtained. Or even if it is obtained, it may be very small. In addition, when the axial length c of the small diameter portion 42 is greater than 70% of the axial length d of the large diameter portion 41, the space for homogenizing the air is narrowed, and the effect of homogenizing the air is obtained. If the axial length c of the small diameter portion 42 is smaller than 3% of the axial length d of the large diameter portion 41, the air inlet portion There is a risk that it will be difficult to secure durability from the strength aspect. However, these conditions vary depending on other conditions of the spray gun (compressed air pressure, conditions such as paint type and viscosity, size of the entire apparatus, required injection efficiency, etc.). The present invention should not be understood in a limited manner.

Next, all the nozzles 13 may be integrally formed, or a part of the nozzles 13 may be formed separately and assembled as shown in FIG. In FIG. 3B, only the inflow port 39 is formed in the opening adjusting member 44 and disposed at the rear end of the main body of the nozzle 13. The small-diameter portion 42 on the adjustment member 44 side is continuous.

Next, as shown in FIG. 3C, the large-diameter portion 41 may be a tapered hole whose diameter gradually increases from the base end side toward the outflow port 40 at the front end. As shown, it may be formed in three stages (or more stages). Further, the large diameter portion 41 and the small diameter portion 42 do not have to be concentrically continuous, and as shown in FIG. In each of the above examples, the large-diameter portion 41 is formed longer than the small-diameter portion 42, but may be reversed or the same length.

In addition, as shown in FIG. 4, a shielding plate 45 may be provided at a distance from the tip of the outlet 40. As this shielding board 45, the thing of patent document 1 or 2 is employable.

The present invention can be applied not only to a spray gun that manually opens and closes a valve, but also to a so-called automatic spray gun in which a spraying operation is automatically controlled by the action of operating air. In addition, the superiority of the low-pressure spray gun becomes clearer, but it does not prevent it from being used for a high-pressure spray gun.

As in the above-described embodiment, if the nozzle air holes 36 are formed in a plurality of stages or tapered holes, the machining cost seems to increase, but by performing drilling etc. from both the front and rear sides of the flange 32, It is easier to work than if it is penetrated by a single drill, and the possibility of damage to the drill can be reduced. Therefore, in terms of processing cost, it is considered that it can be equal to or reduced from the conventional one.
Further, the flow rate of the inner passage 19 and the outer passage 20 can be adjusted simultaneously only by changing the diameter on the inlet 39 side.

DESCRIPTION OF SYMBOLS 11 Spray gun main body 12 Atomization apparatus 13 Nozzle 14 Needle valve 15 Air cap 16 Compressed air introduction path 17 Paint supply path 18 Branch path 19 Inner path 20 Outer path 21 Annular path 31 Tube part 32 Flange 33 Male screw 34 Central hole 35 Paint Jet port 36 Nozzle air hole 37 Base end surface 38 Front end surface 39 Inlet port 40 Outlet port 41 Large diameter portion 42 Small diameter portion 43 Step portion 44 Opening adjustment member 45 Shield plate 51 Air hole 52 Main air hole 53 Auxiliary air hole 54 Pattern air hole 55 Corner 56 Rear end face

Claims (3)

An air cap and a nozzle disposed behind the air cap;
The nozzle includes a cylindrical portion having a central hole through which the paint passes from the proximal end side to the distal end side, and a flange formed so as to protrude in the outer peripheral direction of the cylindrical portion,
The flange includes a nozzle air hole that causes air for discharging the paint to flow out from the proximal end surface of the flange to the distal end surface;
The front air cap includes a paint discharge hole and an atomizing air hole formed around the paint discharge hole,
The atomizing air hole and the nozzle air hole are connected via an annular passage formed between the air cap and the nozzle, and the paint from the paint discharge hole is discharged from the atomizing air hole. In the spray gun for painting that is atomized by the air
The spray air gun for painting, wherein the nozzle air hole is formed such that an outlet opening at the distal end face of the flange is larger than an inlet opening at the proximal end face of the flange. The spray gun for painting is a low pressure spray gun;
The spray gun for coating according to claim 1, wherein a shielding plate is not disposed in front of the outlet of the nozzle air hole. The spray gun for painting is a low pressure spray gun;
The coating spray gun according to claim 1, wherein a shielding plate is disposed in front of the outlet of the nozzle air hole.

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