JP2000051749A - Paint viscosity controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the viscosity of a paint in a water tank to be uniformalized at its early stages by a relatively inexpensive method without largely changing the fundamental structure of a viscosity controller by incorporating a time delay element so that the time is delayed until a solenoid valve is actually closed with respect to a solenoid valve closing signal from a detection device. SOLUTION: In a paint in a paint container 1 which is a paint recovery vessel in a paint recycle system, a suction pipe 3 connected to the suction side of a diaphragm pump 4 driven by compressed air is immersed, and in mix-way of the suction pipe 3, a paint solvent tank 11 is branched and connected. A paint circulating circuit 5 is connected to the discharge side of the pump 4, and a jetting nozzle 6 of the end of the circuit 5 is arranged in the paint vessel 1, and by a jet stream from the jet nozzle 6, the paint is agitated. At this time, a timer 7a is installed as a time delay means for delaying output of a closing signal to a solenoid valve 9 to delay the time until compressed air is fed to an air-operated valve 10 from the solenoid valve 9 to close the valve 10, attaining the optimization of viscosity adjustment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for controlling the viscosity of a paint supplied to a coating machine, and to control the viscosity of a paint in a large-capacity paint tank such as a paint recycling system. And control of a paint viscosity management device.

[0002]

2. Description of the Related Art In a coating operation, viscosity control of a coating material supplied to a coating machine is an important factor for maintaining a constant coating film quality. When the paint viscosity changes, the amount of paint sprayed out by a spray gun or the atomization of spray paint changes,
There is a problem that the thickness of the coating film and the quality of the coating surface are not stable.

The paint viscosity control device used in the present invention is Japanese Patent Application Laid-Open No. 9-225365 "Paint Viscosity Control Device" filed by the present applicant, which incorporates a shaft movement speed detecting device of a double-acting diaphragm pump. With the detection mechanism, calculate the discharge amount of the diaphragm pump from the operation cycle,
The structure is such that the jet pressure is sprayed from the injection nozzle using the discharge pressure of the diaphragm pump into the coating liquid stored in the coating container to perform jet agitation. This is a paint viscosity management device provided with a control circuit for adjusting the viscosity by supplying a solvent while detecting the moving speed of the drive shaft of the diaphragm pump by forming a paint circulation circuit for the paint inside using a diaphragm pump. As a result, the invention provides many effects, such as high-precision paint viscosity management, low probability of mechanical failure, and stable paint supply, enabling high-quality coating. It is.

[0004] However, this paint viscosity control device is designed for a general coating device, and the capacity of a paint container whose paint viscosity is to be controlled is based on a standard capacity.
The capacity of a paint container for a general coating apparatus is mainly 10 liters or 2 liters because the capacity of a paint can is 18 liters.
A 0 liter container is used, and even a large container has a capacity of 40 liters or 60 liters. However, in recent years, Japanese Patent Application Laid-Open No.
With the development of -165863 "Paint Recycling System" etc., a situation has arisen in which the water tank itself of the painting booth has the role of a paint container. In the case where the water tank itself is used as a paint container, the capacity of the water tank becomes 200 to 600 liters.

[0005] For this reason, in a paint viscosity management device designed for a general coating device, there is a problem that the viscosity of the paint cannot be sufficiently controlled in a large-capacity water tank such as a paint recycling system. is there. In the case of paint containers for general coating equipment, paint viscosity can be controlled only by replenishing the evaporation of the solvent from the paint surface, whereas in the paint recycling system, the paint is atomized from the spray gun. The solvent content of the paint mist collected in the water tank without being able to adhere to the painted object is large, and the solvent of the paint solvent from the water tank with a large surface area is evaporated, and the surface of the mist capturing member is always kept wet. In the case of a 200 liter water tank, when the evaporation is severe, it is necessary to supply about 0.1 to 0.15 liter / min of the solvent. That is, in the case of the paint recycling system, the amount of the solvent that needs to be replenished in a unit time is several times to several tens times in comparison with the case of a general coating apparatus.

As a result, with the paint viscosity control device designed for a general coating device, if the supply amount of the solvent to the suction side of the diaphragm pump is increased, the paint viscosity in the paint circulation circuit increases. Because the amount of paint sprayed from the spray nozzle increases sharply and the speed of movement of the drive shaft of the diaphragm pump also increases, the paint viscosity management device determines that the paint viscosity has dropped, and the entire water tank is at the appropriate viscosity. In spite of the absence, the replenishment of the solvent is stopped, and there arises a problem that the entire water tank does not have an appropriate viscosity.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an arithmetic circuit for detecting a moving speed of a drive shaft of a diaphragm pump which is directly related to a discharge amount of a diaphragm pump, and converting the moving speed into a discharge amount and a paint viscosity. In the case of automatically adjusting the paint viscosity by supplying the solvent in relation to the paint viscosity set in advance, even in the situation where the water tank itself of the painting booth such as `` paint recycling system '' has the role of the paint container, An object of the present invention is to make the viscosity of a paint in a water tank uniform at an early stage by a relatively inexpensive method without largely changing a basic configuration of a viscosity management device.

[0008]

According to claim 1 of the present invention,
It has a paint circulation circuit that sucks paint from a paint container that stores paint to be supplied to the coating machine by a double-acting diaphragm pump that is driven by compressed air pressure, and injects and recirculates paint into the paint in the paint container again with an injection nozzle. The diaphragm pump has a detection device for detecting the moving speed of the drive shaft, and a control box having a control circuit operated by a signal from the detection device is separately provided, and an injection nozzle for injecting into the paint is provided. A single-hole fan spray nozzle that jets and stirs the paint stored in the paint container by jet pressure, and supplies a solvent into the paint circulation circuit by opening and closing an electromagnetic valve according to a command from the control circuit of the control box. In a paint viscosity management device provided with a solvent supply mechanism for performing the above operation, in response to a signal for closing the solenoid valve from the detection device, the electromagnetic So it is time delay until the closure is characterized by incorporating a time delay element.

A second aspect of the present invention is characterized in that the time delay element incorporated in the paint viscosity management device of the first aspect is an electric timer incorporated in a control circuit of a control box. According to a third aspect of the present invention, the on-off valve for the solvent is an air operated valve, and the time delay element incorporated in the paint viscosity management device of the first aspect opens and closes the compressed air for operating the air operated valve. This is characterized in that it is an air paper type time delay element of a system for controlling air pressure, which is disposed between the solenoid valve and the air operated valve.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a paint viscosity management device will be described below with reference to the schematic diagram of the entire structure of the present invention shown in FIG. The double-acting diaphragm pump 4 is driven by the compressed air adjusted by the air pressure regulator 18, sucks the paint stored in the paint container 1 through the suction pipe 3, and paints the same pressure as the driving air pressure. Discharge with pressure. The discharged paint passes through a paint circulation circuit 5 composed of a paint pipe having a relatively large inner diameter and a small flow resistance, and is then injected into the paint stored in the paint container 1 by an injection nozzle 6 attached to the tip of the paint pipe. Inject and perform jet agitation. The diaphragm pump 4 is provided with a slit 4b for detecting the moving speed of the drive shaft 4a, and irradiates the slit 4b with an optical sensor composed of a photoelectric element 8 to move the drive shaft in a certain stroke through the slit. The speed is detected, and the amount of paint discharged per cycle of the diaphragm pump is calculated by the arithmetic circuit. An electric circuit that performs an operation based on a signal detected by the photoelectric element 8 is provided in a control box 7 provided separately.

In the control box 7, the correlation between the paint viscosity and the paint ejection amount from the spray nozzle 6, that is, the paint discharge amount of the diaphragm pump under the condition where the spray nozzle 6 is provided, is taken. The moving speed of the drive shaft 4a is stored in advance. When the paint viscosity increases and the moving speed of the drive shaft 4a of the diaphragm pump 4 decreases, the upper limit of the set value range of the paint viscosity is compared with the stored correlation value with the paint viscosity. Then, a command is transmitted to the compressed air ON / OFF solenoid valve 9 provided on the control box side to open the solenoid valve 9.

The compressed air flowing when the solenoid valve 9 is opened is supplied to an air operated valve 10 which is provided on the suction pipe 3 side of the diaphragm pump 4 and is branched. The air operated valve 10 includes a solvent tank 11 for storing a solvent for adjusting the viscosity of the paint, and a needle valve 12 capable of adjusting a flow rate for supplying the solvent supplied from the solvent tank 11 in an appropriate amount. It is connected. The solvent is supplied in an open-type container that is sucked by the suction force of the diaphragm pump 4, or by a method in which the solvent is supplied under high pressure by a paint tank or the like and is supplied with high accuracy at a constant pressure. The adjustment of the needle valve 12 depends on the rate of increase in the viscosity of the paint and the amount of paint in the paint container whose viscosity is to be adjusted, and is used to adjust and set an appropriate amount of the supplied solvent in advance. Therefore, the needle valve 12 is maintained in the set state once adjusted and set according to the paint amount, viscosity, etc. of the paint container for adjusting the coating conditions of the coating apparatus. In particular, when used in a paint recycling system, it is necessary to set a larger amount of solvent to be supplied than in a general coating apparatus.

In the above configuration, when the paint viscosity rises and the drive shaft moving speed of the diaphragm pump slows down, and when the viscosity reaches a preset upper limit viscosity value, a command is issued and the solenoid valve 9 is opened to release compressed air. The air operated valve 10, which is operated with compressed air, is opened, and the solvent is supplied in an appropriate amount via the needle valve 12. When the solvent is supplied and the paint whose viscosity has decreased is sucked into the diaphragm pump, the moving speed of the drive shaft of the diaphragm pump increases, and the control circuit operates when the lower limit of the preset paint viscosity range is reached. Then, the solenoid valve 9 is closed and the air operated valve is closed. Then, by the circulation of the paint, the paint having a low viscosity including the solvent is jet-stirred with the paint stored in the paint container 1 to be homogenized, and when the viscosity rises again and is sucked into the diaphragm pump,
The control circuit operates to open the solenoid valve 9 again to send compressed air to the air operated valve 10, and the same operation as above is repeated. In this manner, the solvent is repeatedly intermittently supplied, whereby the paint viscosity is adjusted in a decay curve,
It is adjusted by repeating until the paint viscosity stabilizes within a preset viscosity range.

At this time, if the opening of the needle valve 12 is simply increased in order to increase the supply amount of the solvent, the paint whose viscosity has been reduced due to the supply of more solvent is sucked into the diaphragm pump, and the The moving speed of the drive shaft increases. And since the moving speed becomes faster and reaches the lower limit of the paint viscosity range set in advance,
The control circuit operates in a short time, the electromagnetic valve 9 is closed, and the air operated valve is closed. For this reason, the present invention incorporates a time delay element from when the control circuit is activated to when the supply of the solvent is stopped by actually closing the air operated valve. As a result, even if the control circuit is operated in a short time by increasing the supply amount of the solvent, the air operated valve does not close for the time set by the time delay element, so that sufficient solvent can be supplied.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to FIGS. However, the parts described in the section of the embodiment are omitted in principle. In the schematic diagram of the entire configuration of FIG. 1, as a time delay element, the output of the closing signal to the solenoid valve 9 is delayed by the electric timer 7a after the control circuit is activated, and the operation timing of the solenoid valve is delayed, so that the solenoid valve is actually Compressed air is sent to the air operated valve to delay the time until the air operated valve closes. If the electric timer 7a is of a type having a variable set time, the delay time can be adjusted according to the capacity of the paint container and the amount of solvent to be replenished. The paint container 1 is a paint recovery tank in a paint recycling system (not shown), and stores a paint capacity of about 200 to 600 liters. The suction filter 2 is attached to the tip of the suction pipe 3 reaching the bottom of the paint container 1 to prevent dust from entering the paint circulation circuit and clogging of the spray nozzle 6. The suction pipe 3 is connected in the middle of the flow path with a flexible paint hose so that it can be arranged according to the length to the bottom of the paint container and its position. A paint solvent supply port is provided on the side of the suction pump 3 on the side of the diaphragm pump by a T-shaped joint. An air operated valve 10 is connected to the paint solvent supply port. The air operated valve 10 is a valve having a known valve mechanism for operating the valve by receiving air pressure from a three-way valve type electromagnetic valve 9 with an air piston or a diaphragm. The needle valve 12 connected to the air operated valve 10 is also a manually-operated general known valve having a minutely adjustable needle valve. The solvent tank 11 is provided with a ball valve 19 necessary for removing the solvent tank 11, and is always open when set. The paint solvent in the solvent tank 11 is supplied by the suction force of the diaphragm pump. However, as described above, the paint solvent may be stored in a pressure feed tank (not shown) or the like, and may be fed under pressure. The solvent supply means does not limit the present invention.

A branch 13 is provided in the paint circulation circuit 5, and when the viscosity of the paint is stabilized, the ball valve 17 of the paint circulation circuit 5 is closed, and the ball valve 14 of the branch 13 is opened. A dual-purpose circuit for regulating the paint and supplying it to the spray gun 19 and the like is provided to supply the paint. When a paint is supplied to a spray gun or the like, it is not possible to perform appropriate viscosity control in a control box. Therefore, when supplying the paint to the spray gun or the like, the function is stopped after the function of the control box is stopped manually or by a switch operated in conjunction with the coating machine such as the spray gun. In addition, since the jet agitation of the injection nozzle 6 can be jetted using the remaining power of the diaphragm pump, when the amount of paint used by the coating machine is small compared to the discharge capacity of the diaphragm pump, the paint circulation circuit It is also possible to continue the jet stirring without completely closing the ball valve 17 of FIG.

Further, as another embodiment, as shown in the schematic diagram of the overall configuration of FIG. 2, the control circuit 7 operates and immediately outputs a closing signal to the solenoid valve 9, so that the solenoid valve 9 is closed. Although the supply of compressed air is stopped and the exhaust is performed, the pneumatic time delay element 9a is incorporated between the solenoid valve 9 and the air operated valve 10, so that the air operated valve 10 is stopped.
And it takes time to stop the supply of the solvent. The configuration of the pneumatic time delay element 9a will be described. The chamber 9a is installed at an intermediate portion between the solenoid valve 9 and the air operated valve 10, and at the same time, the orifice hole or the air amount adjustment is provided at the exhaust port of the three-way valve solenoid valve 9. This is configured by disposing a valve 9b. First, the operation of supplying the solvent will be described. An open signal is output from the control circuit to the electromagnetic valve 9, and compressed air is supplied to the air operated valve 10 and compressed air is accumulated in the chamber 9a. Next, when the control circuit 7 outputs a closing signal to the solenoid valve 9 and the three-way valve solenoid valve 9 is switched, the supply of compressed air to the air operated valve 10 is stopped and the exhaust port of the three-way valve is turned off. Be released. At this time, since the orifice hole or the air amount adjusting valve 9b is provided in the exhaust port, the compressed air accumulated in the chamber 9a is gradually exhausted,
It takes time until the compressed air in the intermediate portion between the solenoid valve 9 and the air operated valve 10 is exhausted, the air operated valve 10 closes, and the supply of the solvent stops. By adjusting the capacity of the chamber 9a and the exhaust amount of the air amount adjusting valve 9b, the delay time can be adjusted according to the capacity of the paint container and the amount of solvent to be replenished.

In this case, a method of arranging a small tank having a capacity for accumulating compressed air in the middle of the pipe as the chamber 9a in the middle of the pipe, or making the pipe itself a tube or a hose and increasing the length thereof, A chamber function may be provided. It is possible to relatively easily and inexpensively modify a paint viscosity management device configured for general coating. Also, a pneumatic time delay element 9a
The same effect can be obtained by using another delay device.

[0019]

As described above, a time delay element can be relatively easily and inexpensively added and modified by using a paint viscosity management device configured for general coating, and a paint recycling system can be obtained. It is possible to control the paint viscosity of a large-capacity paint tank.

[0020]

[Brief description of the drawings]

FIG. 1 is a schematic diagram of the overall configuration of a paint viscosity management device in which an electric timer is incorporated in a control circuit as a time delay element.

FIG. 2 is a schematic diagram of the overall configuration of a paint viscosity management device incorporating a pneumatic time delay element as a time delay element.

[Description of Signs] 1 paint container 3 suction pipe 4 diaphragm pump 5 paint circulation circuit 6 injection nozzle 7 control box 7a electric timer 8 photoelectric element 9 solenoid valve 9a pneumatic time delay element 10 air operated valve 11 solvent tank 12 needle valve

Claims (3)

[Claims] 1. A paint circulation circuit in which paint is sucked from a paint container storing paint to be supplied to a coating machine by a backward-acting diaphragm pump driven by compressed air pressure, and is injected again into the paint in the paint container by an injection nozzle. The diaphragm pump has a detection device for detecting the moving speed of the drive shaft, and a control box having a control circuit activated by a signal from the detection device is separately provided,
The spray nozzle that sprays into the paint is a single-hole fan spray nozzle that sprays and stirs the paint stored in the paint container by the spray pressure, and opens and closes a solvent on-off valve according to a command from the control circuit of the control box. Then, in the paint viscosity management device provided with a solvent supply mechanism for supplying a solvent in the paint circulation circuit, in response to a signal from the detection device to close the on-off valve, until the on-off valve is actually closed A method for controlling a paint viscosity management device, characterized by incorporating a time delay element so as to delay time. 2. A method according to claim 1, wherein the time delay element is an electric timer incorporated in a control circuit of the control box. 3. An air-operated valve as an on-off valve for a solvent, wherein a time delay element is provided between a solenoid valve for opening and closing compressed air for operating the air-operated valve, and air provided between the air-operated valve. The method for controlling a paint viscosity management device according to claim 1, wherein the control method is a pneumatic time delay element of a type that controls pressure.