JPS632661B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic spray coating device, particularly for coating highly viscous paints, such as aggregate-containing paints containing large amounts of glass beads, calcium carbonate, silica sand, and other aggregates. The present invention relates to a coating device suitable for painting.

Aggregate-containing paints are often used to finish the exterior walls of buildings, bridges, etc. with uneven patterns, and the painting methods include air spraying and roller brushing. Recently, in order to reduce the cost of housing building materials, mass production is often carried out in factories, and there is an urgent need to automate the application of aggregate-containing paints to these materials.

However, in the past, painting with aggregate-containing paints was mainly done by hand, making them unsuitable for mass-production painting, and furthermore, the finished appearance was not satisfactory because the atomization of the paint was incomplete in the early stages of painting.

The present inventor has completed the present invention as a result of research into an automatic spray coating device that eliminates these deficiencies and is suitable for use with high viscosity paints.

The present invention provides a needle valve 2 having a tubular structure with an air passage inside that contacts a mouthpiece 4 of a gun head and closes a paint pumping passage 5, an air passage A for opening and closing the needle valve 2, and A spray gun 1 is provided with a low-pressure air path B and a high-pressure air path C, which are connected to each other so as to be able to switch between the two air paths, and the air paths A, B, and C are connected to each other so as to be able to switch between the two air paths. , and an operating section that automatically controls the valves of each air path so that path B is opened and path C is closed at the same time, and paths A and B are simultaneously closed when painting is stopped. This is an automatic spray painting device.

Although the coating device according to the present invention can be applied to all types of paints, it is particularly suitable for paints containing aggregates, which are generally considered to be relatively difficult to spray paint. reveal.

The coating device according to the present invention automatically coats objects to be coated that are mass-produced in factories, etc., and its purpose is to prevent clogging of paint in the paint discharge section of a spray gun, and to prevent paint from clogging from the beginning of spraying. This is due to its excellent atomization. In other words, when spraying paint containing aggregate using conventional equipment, the aggregate tends to clog the tip of the spray gun, reducing painting workability.
Since the paint is discharged without sufficient atomization,
There were some problems with the finish of the painted surface. The present invention eliminates these deficiencies and is characterized by the use of a pipe-structured needle valve as an air path for atomizing paint, and a valve for opening the needle valve (discharging paint) during painting. The spray air path for atomizing the paint is opened earlier than the operating air path, high-pressure air is blown out for a short period of time, and then the system is switched to low-pressure air to perform spray painting. In other words,
Immediately before paint is discharged from the spray gun, high-pressure air for atomizing the paint is blown out to eliminate the above-mentioned defects at the start of painting.

The coating apparatus of the present invention mainly consists of a spray gun and an operating section for automatically opening and closing the valve of the spray gun. FIG. 1 is a sectional view of the spray gun used in the present invention, and FIG. The air circuit diagram for operating and controlling the spray gun, Figure 3, is
3 is an electric circuit diagram for operating and controlling each magnetic valve in the air circuit of FIG. 2. FIG.

The spray gun 1 mainly includes a needle valve 2 having a pipe structure with an air passage inside, a piston 3 fixed to the needle valve 2, a mouthpiece 4 in the gun head, an air path A for operating the needle valve 2, a low pressure air path B connected to the air path of the needle valve 2 in a switchable manner;
It has a high-pressure air path C and a paint pressure feeding path 5, and an air path D opened to the outside of the mouthpiece 4 for adjusting the atomization pattern of the injected paint can also be provided as necessary.

There is an operation section that communicates with the air path A to air path D of the spray gun 1 and automatically controls the pressure feeding of air to each air path. , when starting painting, first open route C, then open route A, then open route B, and at the same time open route C.
The magnetic valves of each air route are automatically controlled so that the air passages A and C are closed at the same time when painting is stopped, and painting is performed automatically.

As an operating section having such a function, for example, one having a control mechanism including an air circuit and an electric circuit as shown in FIGS. 2 and 3 is used.

Specific examples of the coating device according to the present invention and cases in which automatic coating is performed using the same are shown in FIGS.
This will be explained based on FIG.

First, the paint is pressurized by a pressure tank or pump (not shown) and is forced into the gun head through path 5. When not painting, the needle valve 2 is pressed together with the piston 3 by the spring 6, and its tip is in close contact with the mouthpiece 4, so the paint being pumped into the gun head does not spray out from the mouthpiece 4. . Inside the gun head, that is,
The shape of the inner surface of the paint pressure passage 5 and the mouthpiece 4 is preferably curved, and the presence of corners may impede the flow of aggregate contained in the paint and cause clogging. The needle valve 2 has a pipe structure, and one end surface of the needle valve 2 is adapted to be in close contact with the inner surface of the mouthpiece 4. The inner diameter of the needle valve 2 varies depending on the paint to be applied, but for paints containing aggregate, etc. ~4mm,
For other ordinary paints, a thickness of about 0.5 to 2 mm is appropriate.
The size of the ejection hole of the mouthpiece 4 is preferably 4 to 10 mm for aggregate-containing paints, and 0.5 to 3 mm for other paints. The paint is ejected by operating the needle valve 2 against the spring 6 (moving it to the left in the drawing).

That is, by the rotation of the cam 10 of the automatic coating machine 9 that is activated in conjunction with the reciprocating movement of the spray gun 1, the piston valve 11 is raised against the bias of the spring 12, and the limit switch _Ls is turned on. At the same time, pressurized air source and magnetic switch
Open the air path between MV ₁ . cam 10
The shape and rotation speed can be arbitrarily adjusted depending on the size and shape of the object to be coated. When the limit switch _Ls is turned ON, the magnetic valves _MV1 , _MV2 , and _MV3 provided in the control box 7 operate as shown below. Magnetic valve MV ₁ is
It controls air paths A and D, and when the limit switch L _s is turned on, the magnetic valve
MV ₁ is activated after MV ₃ of air path C by timer T ₁ . Air route C
is controlled by the magnetic valve _MV3 , and at the same time as the limit switch _Ls is turned on, the magnetic valve _MV3 is activated and the air path C is opened.
High-pressure pumped air passes through the tube of the needle valve 2 having a tube structure and is ejected from the discharge hole of the mouthpiece 4. After that, contact t ₁ is closed by timer T ₁ and turned ON, MV ₁ is activated and air path A is opened, and the pressurized air enters spray gun 1 and passes through the needle fixed to piston 3. valve 2
is actuated against the spring 6, the needle valve 2 is separated from the mouthpiece 4, and the paint in the paint feeding path 5 is discharged from the outlet hole of the mouthpiece 4, and high pressure is ejected through the inside of the pipe of the needle valve 2. The air flow atomizes the particles and starts painting. Then, after a certain period of time has passed, the timer _T2 of the magnetic valve _MV3 is activated to open the contact _t2 , which turns off the magnetic valve _MV3 and closes the air path C.At the same time, the relay R activates the contact r. close, and magnetic switch MV ₂ operates to open air path B. Also, when the limit switch _Ls is turned off by the cam 10,
All magnetic valves MV ₁ , MV ₂ , and MV ₃ are turned off, and the entire air path is closed.

This will be explained in more detail. Cam 1 of automatic coating machine 9
When the piston valve 11 is opened by the rotation of the piston 1, air is forced to be sent to the magnetic valve _MV1 . On the other hand, the compressed air is supplied by a magnetic valve MV ₂ ,
It is supplied under pressure up to MV ₃ . This air pressure is determined by the air regulators 17 and 19 and the pressure gauge 1.
8 and 20, the pressure is adjusted in advance to a predetermined pressure such that the air path C is at a high pressure and the air path B is at a low pressure.

Next, when the piston valve 11 is activated by the rotation of the cam 10 of the automatic coating machine 9 as described above,
The limit switch L _s is also turned on at the same time, and the magnetic valves MV ₁ , MV ₂ , and MV ₃ operate as described above, so that the spray gun 1 performs automatic painting as described below.

First, when the MV ₃ first opens, high-pressure air from the air path C is blown out through the inside of the needle valve 2 that is in contact with the mouthpiece 4, and the mouthpiece 4 is
Air purge any remaining paint from the outflow hole. After that, MV ₁ is activated with a slight delay and air path A is activated.
The pressurized air opens the needle valve 2, and the paint is discharged into the outflow hole under the high-pressure air jet, where it is atomized and sprayed.

The time difference between when the high-pressure air is ejected and when the paint is ejected can be arbitrarily selected by adjusting the timer _T1 depending on the shape and size of the object to be coated.
After initial atomization by high-pressure air, timer T ₂ activates relay R, which closes MV ₃ and closes air path C. At the same time, contact r ₁ closes and MV ₂ opens, allowing low-pressure air to flow from air path B. Instead, normal spray painting will continue.

The condition is that the time difference between switching from high pressure air to low pressure air does not reduce the coating efficiency.
It varies slightly depending on the properties of the paint, but usually 0.1~
Approximately 0.5 seconds is appropriate.

On the other hand, the air in the path D branched from the path A is appropriately pressure-adjusted and reaches the air cap 8, where the atomization pattern is adjusted.

When the piston valve 11 is closed by the rotation of the cam 10, the pressure air in the air path A is released to the outside, and at the same time, the limit switch L _s is activated.
It is turned OFF, all magnetic valves are closed, the needle valve 2 is brought into close contact with the mouthpiece 4 by the spring 6, and the discharge of paint is stopped, returning to the original non-painting state. The air path D described above is not always necessary and is provided only when it is necessary to flatten the paint spray pattern.

The painting and non-painting states can be controlled as described above by operating the piston valve 11 of the automatic coating machine 9 according to the present invention, and the piston valve 11 is operated by the cam 10. Therefore, the temporal adjustment of the operation of the piston valve 11 can be determined by the shape and rotational speed of the cam 10, and these can be appropriately selected depending on the size of the object to be coated, the amount of coating, etc.

An automatic spray painting device with the above-mentioned spray gun and operation section uses Rethane PG60 White (product of Kansai Paint Co., Ltd., urethane resin paint trade name) and calcium carbonate as an aggregate.
As a result of painting using a high viscosity paint mixed in a 30/70 ratio, it was confirmed that there was no clogging and the finish was good.

Specifically, a 1 m x 1 m x 1 mm steel plate was used as the object to be coated, the conveyor speed was 2 m/min, and the vertical running speed of the spray gun was 30 m/min.
It was hot in minutes. And air paths A, B and C
The pumping pressure of 4Kg/cm ² , 5Kg/cm ² , 6
Kg/cm ² , first, path C was opened to blow out only air for promoting atomization, and then path A was opened to spray the aggregate-containing paint. The atomization of the paint at the initial stage of spraying was very good, and the finish was uniform. After another 0.5 seconds had passed, route B was opened and route C was closed at the same time to continue painting. The inner diameter of the needle in the spray gun is 2.5 mm, and the inner diameter of the nozzle in the nozzle is 8 mm.
The pressure for feeding the paint was 4 kg/cm ² .

In addition, in the above, route A is used as the air route.
and Route B. That is, the object to be coated, conveyor speed, spray gun operating speed, air pressure of route A and route B,
The needle, mouthpiece, and pressure for pumping the paint are as described above, and first open path B to blow out only the low-pressure air for atomization, then after 1 second, open path A to perform painting. Ta. As a result, the atomization state at the initial stage of coating was inferior to that in the above case. In addition, as a paint, the above-mentioned retan
A paint with a lower viscosity than the above was used, which was a mixture of PG-60 and calcium carbonate in a 50/50 ratio.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the automatic spray gun used in the present invention, and FIGS. 2 and 3 are air circuit and electric circuit diagrams of the operating section. 1...Spray gun, 2...Needle valve, 3...
... Piston, 4 ... Mouth part, 5 ... Paint pressure route, 6 ... Spring, 7 ... Control box,
8...Air cap, 9...Automatic painting machine, 10
...Cam, 11...Piston valve, 12...Spring, 17, 19...Air regulator, 1
8, 20...Pressure gauge, A...Air path for needle valve operation, B...Low pressure air path, C...High pressure air path, D...Air path for adjusting coating pattern, L _s ...Limit switch, MV ₁ , MV ₂ ,
MV ₃ ... Magnetic switch, T ₁ , T ₂ , t ₁ , t ₂
...Timer and contacts, R, r...Relays and contacts.

Claims (1)

[Claims] 1. A needle valve 2 having a pipe structure with an air passage inside that contacts the mouthpiece 4 of the gun head and closes the paint pressure passage 5, an air path A that opens and closes the needle valve 2, and an air passage for the needle valve 2. A spray gun 1 provided with a low-pressure air path B and a high-pressure air path C connected to the passage so as to be able to be switched to each other.
In addition, the air paths A, B, and C are set so that when painting starts, first path C is opened, then path A is opened, and then path B is opened and simultaneously closed to path C, and when painting is stopped, paths A and B are closed simultaneously. An automatic spray painting device characterized by comprising an operation section that automatically controls valve operation of each air path.