JPS6247418B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spray gun for painting, particularly an air spray gun.

An air spray gun uses an air flow to atomize paint discharged from a discharge nozzle, and its atomization performance is largely influenced by air pressure and the liquid pressure of the paint. In other words, the air pressure is generally high and 7
Kg/cm ² , usually 2 to 5 Kg/cm ² , and the liquid pressure of the paint is usually 3 Kg/cm ² or less, so that the atomization performance is best when there is a lever-like pressure relationship. A discharge nozzle for paint and an air nozzle for air are set up, and if the liquid pressure is higher than the air pressure, the paint will not be atomized by the air flow, and a spit will occur where the paint will be discharged as a liquid. That's what happens. For this reason, paints that are normally supplied at high pressure are not applied with a spray gun, and even if paints are used at low pressure, the piping system is under pressure to avoid high pressure. Although adjustment means are provided, sometimes high pressures can still be reached, several times higher than normal. If such a situation were to occur even momentarily, a spit would occur in a conventional device in which a discharge nozzle and a needle-type valve were integrally formed, resulting in poor coating. A similar problem occurred even with a type that does not use airflow.

The present invention has been developed in view of these points, and its purpose is to provide a coating that does not cause spitting, can supply paint at high pressure, and can perform good painting without being affected by hydraulic pressure. We provide a spray gun that can.

The present invention will be described below.The present invention is characterized in that a pressure buffer chamber is formed between the discharge nozzle and the valve, and a throttle means such as a choke or orifice is provided in the front stage of the valve. Therefore, the throttle means lowers the liquid pressure of the paint, and the pressure buffer chamber reduces fluctuations in the liquid pressure so that the liquid pressure when passing through the discharge nozzle is approximately constant.

The present invention will now be explained in detail with reference to illustrated embodiments. The illustrated example is an air spray gun, and the grip portion 10
A connecting plug 12 for a compressed air hose is attached to the lower end of the head 11, a connecting plug 13 for a paint hose is attached to the lower surface of the head 11, and a lever 14 pivoted at the upper end is attached to the grip section. 1
0 and the head 11. As is clear from FIG. 2, the head 11 has a main body 15.
, a nozzle block 16 , a double ring 17 ,
Air nozzle block 18 and tightening ring 19
The rear end of the cylindrical nozzle block 16 with the discharge nozzle 1 formed at the tip is
A double ring 17 is screwed onto the main body 15 and is disposed together with a packing 21 between the main body 15 and the flange 20 of the nozzle block 16, and further includes a slope 24 in contact with the slope 23 of the periphery of the flange 20. An air nozzle block 18 with a
It is attached by 9. Nozzle block 1
6 has a valve seat 26 disposed at the rear end opening, which constitutes a needle valve type valve 3 together with a needle 25 that slides in the axial direction in response to the operation of the lever 14.
A pressure buffer chamber 2 is formed between the air nozzle 1 and the discharge nozzle 1 at the front end. A first air pocket 29 and a second air pocket 30 are formed between the block 18 and the block 18. The air nozzle block 18 includes a group of air nozzles 7 located around the discharge nozzle 1, and air nozzles 8 for spray pattern control provided inwardly on a pair of vertically extending wing sections 31, 31, respectively. The air nozzle 7 has a first air reservoir 29, a ventilation hole 28, a space between the double ring 17 and the nozzle block 16, and a packing 2.
1 through the annular space formed by the main body 1
It is connected to the air passage 33 provided in the lever 1.
It is connected to the connection plug 12 via a valve (not shown) that is opened and closed by four operations. The air nozzle 8 is connected to the double ring 1 via the second air reservoir 30.
The valve is connected to the through hole 34 formed in 7, is slidable in the axial direction within the air passage 33, and is formed by a needle 35 having a tip having a smaller diameter than the inner diameter of the air passage 33 and an opening at the rear end of the through hole 34. At 9, the air flow path leading to the air nozzle 8 is adapted to be controlled. On the other hand, the paint flows from the connecting plug 13 through the main body 15 to the valve 3, the pressure buffer chamber 2, and the discharge nozzle 1. It has a chiyoke 4 that is narrowed down to 1/10. In the figure, 39 is a seal, and 40 is a seal presser.

Therefore, when the compressed air and paint piping hoses are connected to each of the connection plugs 12 and 13 and the lever 14 is operated, the compressed air valve is first opened, and then the paint valve 3 is opened. The paint discharged from the discharge nozzle 1 is atomized by the air flow discharged from the air nozzle 7 around the discharge nozzle 1. At this time, when the valve 9 is opened and air flows out from the air nozzle 8, the spray pattern becomes elliptical. In this device, even if the liquid pressure of the paint becomes higher than the air pressure, or even if the paint is sent at a pressure higher than the air pressure, the pressure of the paint decreases while it passes through the chain yoke 4 in the connection plug 13, causing spitting. Moreover, due to the existence of the pressure buffer chamber 2 between the valve 3 and the discharge nozzle 1, even if there are large fluctuations in the paint liquid pressure, or when the valve 3 is opened, the temporary high pressure will be reduced. Even if such conditions exist, these pressure fluctuations will be alleviated and no spitting will occur.

In the above embodiment, the throttle means 4 is shown as the restricting means, but this may be an orifice, and the restricting means can be easily replaced according to the fluid pressure of the paint, and maintenance is also easy. In order to achieve this, an example has been shown in which the connecting plug 13 is provided with a restricting means, but it goes without saying that the restricting means may be provided at an appropriate position upstream of the valve 3.

As described above, in the present invention, since the pressure is reduced by the presence of the squeezing means, spitting does not occur even when the liquid pressure of the paint increases or even when the paint is fed under high pressure. Even when the paint is supplied at high pressure, it is possible to paint with a spray gun, and since a pressure buffer chamber is formed between the valve and the discharge nozzle, it is difficult to open the valve. Even if there is a temporary high pressure fluctuation, such as when the pressure is high, no spitting will occur, and a clean coating can always be achieved.

[Brief explanation of the drawing]

FIG. 1 is a front view of an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the same head, in which 1 is a discharge nozzle, 2 is a pressure buffer chamber, 3 is a valve, and 4 is a choke as a throttle means. , 13 indicates a connection plug.

Claims (1)

[Scope of Claims] 1. A spray gun characterized in that a pressure buffer chamber is formed between a discharge nozzle and a valve, and a throttle means such as a choke or orifice is provided in front of the valve. 2. The spray gun according to claim 1, wherein the throttle means is formed in a connection plug to which a hose is connected.