JPH02237662A - Nozzle tip for spraying liquid under pressure - Google Patents

Abstract

PURPOSE:To rapidly generate a turbulent flow of coating material at the rear side of an orifice and to suppress the formation of a tail by regulating the depth of a hole having a curved surface in a nozzle tip to a specified value or below. CONSTITUTION:When an orifice is made in a nozzle tip having a rear hemispherical recess by cutting a groove reaching the recess and a liq. jetted from the orifice under pressure is atomized by collision with the air, an opening 12 for the orifice and a triangular groove-shaped notch 13 are made in the nozzle tip, a hemispherical surface 14 and the boundary 15 between the surface 14 and the diameter (d) 16 of a cylindrical part are formed in the nozzle tip and the depth of the hemispherical part 14 from the tip to the boundary 15 is regulated to <=0.5d. A turbulent flow of coating material is rapidly generated at the rear side of the orifice and the formation of the tail can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spray nozzle that pressurizes liquid to high pressure and injects it into the air at high speed through a small-diameter nozzle hole to atomize it by friction with the air.

BACKGROUND ART Conventionally, spray nozzles used for airless painting and the like have used fan-shaped nozzles that create a conical pattern (referring to the shape of paint sprayed on a painted surface; the same applies hereinafter).

This nozzle chip has a hemispherical recess on the back surface, and a triangular groove is cut from the front surface to form an orifice (liquid spout). The liquid injected from the orifice collides with the air, becomes atomized, forms a suitable spray distribution, and adheres to the object to be coated as a coating film. The amount of fluid ejected from the nozzle is determined by the fluid pressure and the area of the orifice. The pattern width (width in the longitudinal direction of the spray shape) is determined by the diameter of the tip hole in the nozzle tip (diameter of the cylindrical part at the tip) and the depth of cut into the nozzle tip by making the angle of the acute triangular groove. It is formed.

Generally, when painting with an airless spray, the spray amount and pattern are adjusted so that the thickness of the coating is thinner in the areas that are overcoated, in order to enable overcoating. Improper fluid pressure, paint viscosity, or nozzle size can cause coarse side streams to separate from the paint stream exiting the orifice, creating tails at each end of the paint film that can cause streaks on the painted surface. It adheres in a pattern.

A conventional nozzle tip has a donut-shaped back surface or a concave curved surface formed by combining two hemispheres with a large radius of curvature, and the depth of the curved hole exceeds the radius of the cylindrical portion on the back surface of the nozzle.

In order to solve the above problems, the present invention makes the depth of the curved hole in the nozzle chip 0.5d or less, and o. 5d′f
The turbulent flow of the paint at the back surface of the orifice is made more rapid than in the case of exceeding t, and the tail is reduced by this effect.

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

A cross-sectional view of the fan-shaped nozzle is shown in FIG. 1 is a nozzle tip, which is driven into the nozzle case 2. 3 represents the triangular groove at the tip. FIG. 2 is a side view from the left side of FIG. 1. 4 is an orifice of a nozzle chip, and 5 is a nozzle chip.

The third heel is an enlarged view of the nozzle tip in FIG. 2, with reference numeral 6 indicating the opening of the orifice, and 7 indicating the notch of the nozzle tip formed by the triangular groove. FIG. 4 is an enlarged view of the tip of the nozzle tip in FIG. 1, and is of a conventional nozzle tip.

8 represents a hemispherical surface, and 9 represents a boundary between the hole diameter 10 of the cylindrical portion and the hemispherical surface 8. The depth from the tip of the hemispherical surface 8 to the boundary 9 exceeds 100 half of the hole diameter.

1l indicates the cutting angle of the triangular groove.

FIG. 5 shows the nozzle chip of the present invention, where 12 shows the orifice opening and 13 shows the triangular groove cut into the nozzle chip. FIG. 6 is a cross-sectional view of the nozzle tip, where 14 is a hemispherical surface, 15 is a hemispherical surface 14, and a hole diameter 16 in the cylindrical portion.
(=d), from the tip of hemispherical part l4 to burial mound 1
The depth up to 5 is 0.5d or less. 17 indicates the cutting angle of the triangular groove.

6 Effect of invention Figure 7 is 41st! A cross section of a coating film when the conventional nozzle tip shown in I is used is shown. The peaks C separated at both ends of the coating film b applied to the object a are called tails. FIG. 8 shows a cross section of a coating film coated according to the present invention. The coating film b' is formed flat on the object a, and the tail defect shown in FIG. 7 is eliminated.

[Brief explanation of drawings]

Figure 1: Conventional airless nozzle Figure 4: Enlarged view of the tip of a conventional airless nozzle Figure 6 2 Tip of airless nozzle according to embodiment of the present invention 1: Nozzle tip 2: Nozzle case Figure 1 Figure 2 14: Hemispherical recess according to invention Figure 3 No.51!1 Figure 4 Figure 6 Figure 7 hand Continued Supplementary Positive book (method) June 7, 1999

Claims (1)

[Claims] In a nozzle chip that has a hemispherical recess on the back surface, opens an orifice by cutting a groove from the front surface to reach the recess, and injects pressurized liquid from the orifice to collide with the atmosphere and atomize it. , the liquid pressurization characterized in that the recessed portion is formed in an arch shape by a plurality of spherical portions having a radius of curvature larger than the radius of the hemisphere, and the height of the arch is set to be equal to or less than the radius. Spray nozzle tip