JPS62204872A - Spray gun - Google Patents

Abstract

PURPOSE:To enhance atomizing effect and coating efficiency, by positively forming the paint injected from a paint jet orifice into a thin film by centrifugal force by providing a paint revolving means in the upstream side close to the paint jet orifice prior to forming the same into a thin film by an air stream. CONSTITUTION:The paint from a paint supply passage 9 is passed through the paint flow passage 18 in a revolving core 19 with the opening of a needle valve 8 due to the retraction thereof and, in this paint passing process, a revolving stream is imparted to the paint. Therefore, the paint is radially injected by centrifugal force when injected from a paint jet orifice 6 to be positively formed into an expanded thin film along a conical opening part 5 and impinges against and contacts with the conical annular air film from an air jet orifice 10 in a state uniformized by a part of an air stream backward flowing on an axis and atomized. As a result, atomizing efficiency is markedly enhanced to enable even the use of high viscosity paint and the supply pressure of paint or air is lowered to make it possible to also attain the conservation of energy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spray gun for painting, particularly a spray gun suitable for finishing painting.

[Problems with conventional technology]

A paint spout is provided at the center of a conical spout opening that expands forward, and an air jet nozzle formed by a conical annular slit is provided on the circumferential side of the conical opening so that the spouted air is aligned with the axis of the spout opening. They are arranged on a common axis so that they are formed into a hollow cone shape that narrows forward, and a hollow cone-shaped air film that is concentrated in the front is ejected from the air outlet, thereby causing a collision at the axial position. A part of the air flows backward on the axis, causing the paint jetted from the paint jetting port to spread along the conical surface of the jetting port, becoming a thin film, colliding with the air film from the air jetting port, and then being entrained. Front axis position-C
Japanese Utility Model Publication No. 54-5823 discloses a prior art technique in which collisions occur intensively, thereby effectively atomizing the particles.

However, in this type of spray gun, the amount of paint discharged is controlled by changing the paint supply pressure and by selecting the diameter of the paint outlet. When the paint supply pressure is lowered in order to reduce the amount of paint, the paint ejected from the paint nozzle is concentrated downwards without being spread over the entire area of the conical opening, resulting in incomplete atomization. In addition, there is the disadvantage that the spray pattern is distorted, and if the diameter of the paint injection nozzle is made small, the paint tends to concentrate in the axial direction without spreading, which not only has the disadvantage of significantly reducing the atomization effect, but also causes the nozzle to become clogged. There is a disadvantage that cleaning efficiency is low when changing the color.

[Object of the present invention]

The present invention is of this type, which can limit the amount of paint discharged to a significantly small amount without reducing the diameter of the paint nozzle, improve the atomization effect and coating efficiency, and achieve uniform atomization. The purpose is to provide a spray gun.

〔Features〕

In order to achieve the above-mentioned object, the present invention provides a paint swirling means upstream close to the paint spout so that the paint spouted from the paint spout is brought into a state along the conical opening surface before being thinned by air flow. The paint is actively thinned by centrifugal force, and the paint is uniformly thinned by the airflow, and then it collides with the conical annular airflow from the air outlet. It is characterized by the fact that

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the spray gun of the present invention will be described in detail with reference to the illustrated embodiments.

A paint nozzle member 2 is attached to the front end of the spray gun body 1, and an air nozzle member 3 is attached to the outside of the paint nozzle member 2 with a nut 4 in a common axis relationship. In addition to forming a conical opening 5 that opens and a paint spout 6 at its center, a valve seat 7 is provided upstream of the paint spout 6, and a needle valve 8 corresponding to the valve seat 7 can be moved back and forth. By reversing the needle valve 8 as necessary while the needle valve 8 remains opposite to the spray gun body 1, the paint fed from the paint supply passage 9 in the spray gun body 1 can be jetted forward through the paint spout 6. Further, on the outer circumferential side of the conical opening 5 in the paint nozzle member 2, a conical annular air outlet 10 that narrows forward is provided between the outer circumferential edge of the tip of the paint nozzle member 2 and the inner circumferential edge of the tip of the air nozzle member 3. A hollow conical annular shape that narrows the pressurized air supplied through the air passage 11 provided in the spray gun body 1 and the air passage I2 formed in the paint nozzle member 2 forward from the air outlet 10 while remaining in place. of air for atomization can be ejected, so that air ejection port
After the paint ejected from the paint spout 6 is spread and moved forward along the conical surface of the opening 5 by the backflow air generated by the reversal caused by the collision of the hollow conical airflow concentrated at the front axis position from zero. , it collides with the airflow ejected from the air jet port 10, and collides intensively at the front axis position while being accompanied by this airflow, and is effectively atomized by this collision. In this respect, there is no difference in nature from the prior art.

In the present invention, a paint swirling means is provided upstream close to the paint spouting port 6, and in the illustrated embodiment, a hollow portion 13 is formed in the paint nozzle member 2 to form a hollow portion 13 at its front end, that is, the paint spouting means. At the back of the outlet 6, a catch 16 having a conical surface 14 expanding rearward and a through hole 15 having the same diameter as the paint spout 6 is fitted, and corresponding to the catch 16,
A conical head 17 that faces the conical surface 14 at the tip and a paint flow channel 18°18 formed in a "lotus" shape on the conical head 17.
A rotating core 19 is screwed into the paint nozzle member 2 from the rear so that the head 17 at the tip is in pressure contact with the conical surface 14 to constitute a paint swirling means, and the rotating core (1)
In addition to fixing the valve seat 7 to a portion near the rear end of the valve seat 9, the needle valve 8 corresponding to the valve seat 7 is provided so as to be movable forward and backward from the rear, and a T-shaped flow path extends from the valve seat 7 to the front. 20 is provided to connect the flow path 20 and the inner surface of the hollow portion 13 to the swirling core 19.
The paint can flow into the paint flow path 18 through an intermediate gap between the paint supply path 9 and the rotating core 1 as the needle valve 8 is retracted and opened.
While the paint is passed through the "lotus" shaped flow path (■8) in 9, a swirling motion is applied during the passage, so that when the paint is spouted from the spout 6, it is spouted radially due to centrifugal force, forming the conical shape. The film is actively spread and thinned along the opening 5, and in a uniform state combined with the spreading action of a part of the air flow flowing backwards on the axis, a conical annular air film from the air outlet 10 is formed. By making it possible for the particles to collide with each other, atomization caused by this collision as well as atomization caused by concentrated collisions on the front axis makes it possible to spray extremely fine atomization. It should be noted that the means for imparting swirling motion to the paint is not limited to the above-mentioned structure, and other structures may of course be adopted.

According to the above configuration, an annular paint film pattern appears on the surface to be painted, but in order to obtain an elliptical paint film pattern, the conical spray may be flattened into a fan shape by an air flow, Equipment for which this is not possible include, as shown in the figure, forward-facing protrusions 21 at two opposing locations near the outer periphery of the air nozzle member 3;
21 are formed symmetrically, and this protruding portion 21 is provided with a flow path 22 in the front-rear direction and obliquely inward flattening air nozzles 23 and 24 communicating with this flow path 22 in a forward direction. The gun body 1 is provided with an air supply passage 25 that communicates with the passage 22, so that relatively low-pressure pressurized air is blown from air nozzles 23, 24 into a conical spray as required. By doing so, the spray may be transformed into a fan-shaped spray.

Further, in order to adapt the spray gun of the present invention to electrostatic painting, conductive wires 26 and 27 passing through the spray gun body 1 and the air nozzle member 3 are provided with intermediate connections intervening. The tip of the wire 27 is used as a needle-shaped electrode 28, which is connected to one protrusion 21 of the air nozzle member 3.
By protruding diagonally inward from the tip and placing it near the base end of the spray, a high voltage is applied to this needle electrode 28 from a high voltage power source 29 via a high safety resistor 30 and conductive wires 26 and 27. Alternatively, the conductive wire 27 and the needle electrode 28 may be omitted and the paint nozzle member 2 may be made of metal, and the paint nozzle member 2 may be electrically conductive. It is also possible to electrically connect the wire 26 and use the tip of the paint nozzle member 2 as a charging electrode, thereby further improving the atomization efficiency and coating efficiency.

When using the above configuration, the paint supply pressure is normally set at 0.2 to 0. υ = about 9/cl, and the air supply pressure is selected to be about 1 to 3. By selecting these supply pressures, it is possible not only to match the viscosity and properties of the paint, but also to adjust the spray pattern. It is natural that the above-mentioned pressure value is not limited to this and can be changed appropriately. [Effects of the Invention] As explained above, the present invention has the following advantages: In contrast to the previous method, where the paint just after being spouted was made into a thin film at the conical opening only by the vortex flow of backflow air, by giving the paint a swirling motion just before the jetting port, the paint was jetted from the jetting port and at the same time, it was thinned at the opening due to centrifugal force. Since the conical surface can be actively spread, it significantly improves the atomization efficiency and is suitable for spraying high-viscosity paints.It also realizes uniform atomization, which reduces the paint supply pressure and air flow. The supply pressure can be lowered, which saves equipment and power for pressurization, and also reduces the propulsion speed of the mist droplets to reliably prevent rebound from the surface to be coated and improve the coating. Efficiency can be significantly improved, and since it can be adapted to spraying at a low discharge rate without reducing the diameter of the paint jet nozzle, it is suitable for finish painting and can prevent nozzle clogging. Moreover, it has advantages such as good cleanability.

[Brief explanation of drawings]

The drawing shows one embodiment of the spray gun of the present invention,
FIG. 1 is a longitudinal sectional view, and FIG. 2 is a perspective view of the tip head of the pivoting core. 5... Spray opening 6... Paint spout 10... Air spout 16... Seat 19... Swivel core

Claims (1)

[Claims] A paint spout is provided at the center of a conical spout opening that expands forward, and an air spout with a conical annular slit is provided on the circumferential side of the spout opening. The spray gun is of a type in which the spray gun is arranged in a common axis relationship so as to form a cone-shaped jet, and a paint swirling means is provided upstream near the paint spout to direct the paint spouted from the paint spout into the conical jet. A spray gun characterized by actively forming a thin film along the opening.