JPH0237226B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a painting method that allows color change between painting with one paint and painting with another paint to be carried out smoothly without wasting paint.

A color change valve device that combines a paint sprayer that sprays paint toward an object to be coated, and a plurality of paint valves, thinner valves, and air valves, and switches the supply of each paint, thinner, and air to the paint sprayer. and a pump that sends each paint and thinner to the color change valve device, and paints while changing the color as appropriate depending on the type of paint to be applied to the object to be coated. Painting methods for carrying out the work are known from the prior art. Conventional painting methods generally include a pre-color painting process in which one paint is supplied to a paint machine to perform the painting process, and a space between the color change valve device and the paint machine is cleaned and filled with another paint. The process consists of a color changing process, and a next color painting process, in which painting is performed using the other paint. In order to use the paint remaining in the piping between the color change valve device and the paint sprayer without wasting it for painting, we do not start the cleaning process immediately after closing the first color change valve, but instead There are also known devices that continue painting with the previous color while pushing out the colored paint.

By the way, the conventional method described above in which painting is performed while extruding the previous color paint involves opening the air valve of the color change valve device and pushing out the previous color paint using the pressure of compressed air supplied from the air valve. As a result, there were drawbacks as shown below.

First of all, since air is compressible,
The extrusion force of the pre-color paint is not constant, which causes the amount of paint discharged from the paint sprayer to change, resulting in the inability to extrude a sufficient amount of the pre-color paint and a considerable amount of paint being wasted. However, during the painting process, the paint was pushed out and air was blown out from the paint sprayer, resulting in uneven coating on the object being coated.

Secondly, after the previous color extrusion painting process is completed, it is necessary to clean the area between the color change valve device and the coating machine, but during this cleaning process, a large amount of the previous color paint is not pushed out by the extrusion air. Since it adheres to the inner walls of piping, cleaning work is troublesome and requires a lot of time.

Thirdly, in the case of an electrostatic painting method in which painting is performed by applying a high voltage to a paint sprayer, if metallic paint is supplied to the paint sprayer, the high voltage applied to the paint sprayer will cause the There were drawbacks such as dielectric breakdown occurring inside the paint and the risk of short circuits occurring between the paint and the metallic paint.

The present invention has been made in order to improve the above-mentioned drawbacks of the prior art, and it is possible to quickly and safely change the color between painting with the previous color and painting with the next color without wasting paint. The purpose of this invention is to provide a coating method that enables the following.

In order to achieve the above-mentioned object, the coating method according to the present invention includes providing a color change valve device with a pre-color coating step in which the object to be coated is coated by supplying one coating material to a coating machine. The pre-color main painting process is carried out by opening one of the paint valves, which is then closed, and the thinner valve is opened to adjust the pressure at which thinner is discharged to the paint sprayer. By supplying the previous color while pushing out most of the paint remaining between the color change valve device and the paint sprayer to the paint sprayer at the same discharge rate as during the main painting process of the previous color. Its feature is that it consists of a pre-color extrusion painting process in which painting is continued.

Embodiments of the present invention will be described below based on the drawings.

1 and 2 show an example of a coating device used in the coating method according to the present invention.

First, in Figure 1, 1 is the object to be coated (not shown)
1 shows a coating machine that sprays paint toward a target, and the coating machine 1 is of a hydraulic atomization type, for example. One end of a pipe 2 is connected to the coating machine 1, and the pipe 2
The other end is a manifold 4 that constitutes the color change valve device 3
It is connected to the. A large number of pneumatically operated switching valves are attached to the manifold 4, and among these switching valves, 5 ₁ , 5 ₂ , ... 5 _N-1 , 5 _N are paint valves, and each of the paint valves 5 ₁ , 5 _{2 , .} Of these paint supply systems, the paint supply system 6 ₁ connected to the paint valve 5 ₁ is connected to the paint circulation 7 ₁ and the paint provided between the paint circulation 7 ₁ and the switching valve 5 ₁ . The paint supply pipe 8 ₁ has a supply pipe 8 ₁ .
On the way, there is a paint regulator 91 that controls the flow rate of paint flowing from the paint circulation ₇₁ to the paint supply pipe ₈₁ , and a paint regulator ₉ when the paint valve ₅₁ is closed. The pump ₁₀₁ circulates the paint supplied from the paint supply system ₆₁ within the paint supply system ₆₁ . The paint valves 5 ₂ to 5 _N are also provided with paint supply systems 6 ₂ to 6 _N similar to the paint supply system _{6 1} , but illustration thereof is omitted.

Next, reference numerals 11 and 12 indicate a thinner valve and an air valve, respectively, among switching valves attached to the manifold 4, and the thinner valve 11 and the air valve 12 are located on the most upstream side of the manifold 4. A thinner supply system 13 is connected to the thinner valve 11,
The thinner supply system 13 is the aforementioned paint supply system _61.
〜6 Same as _N , thinner circulation 14,
It is composed of a thinner supply pipe 15, a thinner regulator 16, and a circulation pump 17. Further, 18 is an air compressor, and the air compressor 18 is connected to the air valve 12 via an air pipe 19.
is connected.

Next, 20 indicates a pressure regulating valve interposed in the middle of the pipe 2, and the pressure regulating valve 20 maintains the pressure of the paint discharged from the coating machine 1 at a constant level by adjusting its opening degree. It is configured to hang. A control device 21 is provided to adjust the opening degree of the pressure regulating valve 20. The control device 21
As shown in FIG. 2, it includes a timer 22, a D/A converter 23 that converts the digital signal from the timer 22 into an analog signal and outputs it, and an electrical signal from the D/A converter 23 to the air. An electro-pneumatic converter 25 converts the air supplied from the source 24 into a pressure signal. The air pressure signal obtained in this way is supplied to the pressure regulating valve 20 via the pipe 26, and becomes control air for adjusting the opening degree of the pressure regulating valve 20.

The coating apparatus for carrying out the coating method according to the present invention has the above-described configuration, and the coating machine 1 is installed in an industrial robot or reciprocator, and the coating objects conveyed by a conveyor are sequentially colored. This is suitable for use when painting while changing. The painting method involves a pre-color painting process in which one object is coated with one paint, and then the color of the paint is changed in order to paint the next object to be painted with a different paint. It consists of a color change process and a next color painting process in which the object to be coated is coated with the other paint.

Therefore, in the pre-color painting process, painting is performed with paint A supplied from paint valve ₅₁ , and in the next color painting process, painting is performed with paint B supplied from paint valve ₅₂ . This will be explained in detail with reference to FIG.

First, the paint valve ₅₁ is switched to the state where it is connected to the manifold 4, and the pump ₁₀₁ is driven to transfer the paint A supplied from the paint circulation ₇₁ to the paint supply pipe ₈₁ via the manifold 4 and the pipe 2. and supplies it to the coating machine 1. At the same time, control air is supplied from the control device 21 to the pressure regulating valve 20 via the piping 26, so that the pressure regulating valve 20 is fully opened. As a result, the paint A is supplied to the coating machine 1 via the pressure regulating valve 21, where it is atomized by hydraulic pressure and is flown toward the object to be coated. This is the pre-color main painting process shown by A in Fig. 3. As a result, the predetermined portion of the object to be coated is coated. Although the thinner pump 17 is being driven during this pre-color main painting process, the thinner valve 11 is in a state to form a circulating flow in the thinner supply pipe 15.

After that, switch the paint valve 5 ₁ and open the manifold 4.
Cut off the supply of paint A to. At the same time, the thinner valve 11 is switched to connect the thinner supply pipe 15 to the manifold 4, and the thinner sent from the thinner pump 17 is supplied to the manifold 4.
Here, since paint A remains between the tip of the manifold 4 and the coating machine 1, this paint A is pushed out to the coating machine 1 by the thinner. Therefore, the remaining portion of the object to be coated continues to be coated with the paint A that has been extruded in this manner. This is the pre-color extrusion painting process, as shown by B in FIG. In this case, thinner has a lower viscosity than paint, so during the pre-color extrusion painting process, the piping
When the amount of thinner in the pipe 2 increases, the pipe resistance in the pipe 2 decreases and the extrusion pressure of the paint increases.
If the amount of paint discharged during the pre-color extrusion coating process increases in this manner, the uniformity of the paint film on the object to be coated will be impaired. In order to prevent this pressure increase, a pressure regulating valve 20 is provided in the middle of the pipe 2, and the supply pressure of control air to the pressure regulating valve 20 is gradually lowered during the pre-color extrusion painting process. As a result, the opening degree of the pressure regulating valve 20 gradually decreases, and the amount of paint A supplied to the coating machine 1 remains the same as the amount supplied during the previous color main painting process, regardless of the increase in the amount of thinner in the pipe 2. Therefore, the coating film on the object to be coated becomes uniform, and problems such as uneven coating do not occur. This pre-color extrusion painting process is continued until just before the mixture of paint A and thinner starts to be extruded from the paint sprayer 1 at the boundary between the paint A and the thinner, and then the thinner valve 11 is switched to remove the thinner. The supply to manifold 4 is cut off. Here, since the total volume of the flow path between the manifold 4 and the sprayer 1 is constant, and both the paint A and the thinner are incompressible liquids, it is necessary to set the switching timing of the thinner valve 11 in advance. In this case, a fixed amount of paint A is always extruded, and problems such as waste of paint due to insufficient extrusion and uneven coating due to over extrusion do not occur. Furthermore, since thinner is a liquid with good insulating properties, even if the paint A is a metallic paint, there will be no accident in which the high voltage applied to the coating machine 1 is short-circuited during this pre-color extrusion painting process.

In this way, the pre-color painting process is formed by the pre-color main painting process and the pre-color extrusion painting process.

Next, when the pre-color painting process is completed, a color changing process between paint A and paint B begins. This color change process consists of a cleaning process and a preparation process for painting the next color.

First, in the cleaning process, as shown by c in FIG. 3, control air is supplied to the pressure regulating valve 20 to open it, and the air valve 12 is switched to supply air to the coating machine 1 from the manifold 4 through the piping 2. are supplied, and the thinner and the mixture of the thinner and paint A are extruded from their insides using air pressure. Thereafter, the thinner valve 11 is switched to the state where it is connected to the manifold 4, and cleaning thinner is supplied to wash away the paint A adhering to the walls of the pipe 2 and the like. And this air,
Repeat the supply of thinner several times, and then
After the pipe 2 and the sprayer 1 are completely cleaned, air is supplied from the manifold 4 through the pipe 2 to the sprayer 1.
Finish the cleaning process by blowing in and wiping the thinner from their interior. Here, since thinner has already been supplied to most of the manifold 4 and piping 2 during the pre-color painting process before starting the cleaning process, the number of times thinner is supplied during the cleaning process can be reduced. This will save time.

When the cleaning process is completed as described above, the paint valve 52 is switched to supply paint B to the manifold ₄ as shown in Figure 3D, and the paint B is supplied to the manifold 4, and the pipe 2 and the paint sprayer 1 are
Fill with paint B. This is the preparation process for painting the next color.

After completing the preparation process for painting the next color, paint valve 5 ₂
The connection between the machine and the manifold 4 is cut off, and the pressure regulating valve 20 is also closed, and the machine waits in this state until the next object to be coated reaches the coating zone. When the object to be coated is transported to the coating zone, the paint valve ₅₂ is switched to the state where it is connected to the manifold 4 again as shown by E in FIG. is supplied to open the pressure regulating valve 20 again.
As a result, the object to be coated is coated with paint B. This is the next color painting process.

By repeating each pre-color process, the painting work can be smoothly performed while sequentially changing the color of the object being conveyed by the conveyor. Moreover, it saves paint when changing the paint color.
In addition, high-speed color change is possible.

It should be noted that the coating device in the above-mentioned embodiment is merely an example, and the point is that it is sufficient to be able to carry out the method described above, and the device configuration is limited to that shown in Fig. 1. It is not something that will be done. For example, the coating machine 1 may be not only a hydraulic atomizing type but also an air atomizing type, a rotating atomizing head type, etc. Further, it may be an electrostatic coating device that applies a high voltage to the coating machine 1 as desired. Further, the paint supply system and the thinner supply system are shown in which paint and thinner are supplied from the paint circulation and the thinner circulation, respectively, through a regulator, but such a circulation Instead of the dye system, a system may be used in which the paint is supplied from a paint tank or a thinner tank. Furthermore, although the pressure regulating valve 20 has been described as being pneumatically operated, it may be an electromagnetically operated pressure regulating valve or the like as long as the valve opening degree can be adjusted over time. . Further, the supply pressure of the control air to the pressure regulating valve 20 is not limited to being changed stepwise, but may be changed continuously. Further, the signal for changing the supply pressure of control air to the pressure regulating valve 20 is not limited to the timer 22, and may be obtained from, for example, a conveyance speed signal of a conveyor. Furthermore, the coating machine 1 is not intended to be attached to an industrial robot or a reciprocator, but can be fixedly installed depending on the shape of the object to be coated, or can be used as a handgun. On the other hand, among the steps constituting the coating method, the next color preparation step and the next color coating step may be performed continuously.

As explained in detail above, the painting method according to the present invention includes a main color painting process in which the color paint is supplied to the paint machine, and a paint spraying process in which the paint is discharged from the paint machine. By supplying thinner to the coating machine while adjusting the pressure so that the discharge amount is the same as during the main color painting process, painting of the previous color continues while pushing out the previous color paint remaining between the color change valve device and the coating machine. Since it is composed of a pre-color extrusion painting process, the following effects can be achieved.

By setting the total discharge amount of thinner supplied during the pre-color extrusion painting process, the pre-color paint remaining in the piping etc. can be almost completely used for painting, and paint can be saved. This also applies even if the piping between the paint sprayer and the color change valve device is long, so if the distance between the paint sprayer and the color change valve device is large, the savings in paint will be extremely large. Become.

The discharge flow rates of the pre-color paint and thinner are the same, and both the paint and thinner are incompressible liquids, so
The amount of paint supplied to the coating machine during the pre-color extrusion coating process is the same as that during the pre-color main coating process, so the coating film on the object to be coated during both processes is constant and the coating quality is maintained at a good level. Can be done.

During the pre-color extrusion painting process, the area upstream from the boundary between the thinner and the paint has already been cleaned, making it possible to shorten the cleaning process and enable high-speed color changes. becomes.

Even when high voltage is applied to the paint sprayer and metallic paint is used for painting, since thinner is an insulating substance, there is good insulation between the paint sprayer and the color change valve device during the pre-color extrusion painting process. Therefore, the high voltage applied to the coating machine does not cause short-circuit accidents, and coating can be performed safely.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing an apparatus for implementing the coating method of the present invention, Fig. 2 is a circuit diagram of a control device, and Fig. 3 is a time chart showing each step of the coating method of the present invention. . 1... Painter, 2... Piping, 3... Color changing valve device, 4... Manifold, 5 ₁ to 5 _N ... Paint valve, 6 ₁ ... Paint supply line, 10 ₁ , 17... Pump , 11... Thinner valve, 12... Air valve, 13...
...Thinner supply line, 20...Pressure regulating valve, 21...
...Control device, A...Previous color main coating process, B...Previous color extrusion coating process, C...Cleaning process, D...Next color preparation process, E...Next color coating process.

Claims (1)

[Claims] 1. A color changer that combines a paint sprayer that sprays paint toward the object to be coated, and multiple paint valves, thinner valves, and air valves, and switches the supply of each paint, thinner, and air to the paint sprayer. A pre-color painting step in which painting is performed by supplying one paint to the paint machine using a painting equipment having a valve device; In a painting method comprising a color changing step in which the paint is filled between the color changing valve device and the paint sprayer, and a next color painting step in which painting is performed with the other paint, the previous color painting step is performed in the paint valve. A pre-color main painting step in which one paint valve is opened, and the first paint valve is closed and the thinner valve is opened to supply thinner to the coating machine while adjusting the discharge pressure. Preferably, most of the paint remaining between the color change valve device and the paint sprayer is extruded into the paint sprayer while extruding the previous color so that it is discharged into the paint sprayer at the same discharge rate as during the main painting process of the previous color. A painting method characterized by comprising a pre-color extrusion painting process in which painting is continued.