JPH09225365A - Apparatus for controlling viscosity of coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the viscosity of a coating material at high precision by constituting a coating material circulation path for a coating material in a coating material container using a reciprocal diaphragm pump, detecting the speed of the movement of a driving shaft of the diaphragm pump, and installing a controlling circuit to supply a solvent for a coating material and adjust the viscosity. SOLUTION: A coating material in a coating material container 1 is sucked through a pumping up pipe 3 by a diaphragm pump 4 and jetted to the coating material in the coating material container 1 through a jetting nozzle 6 after passing a coating material circulation path 5 to carry out jet stirring. At that time, in order to detect the speed of the movement of a driving shaft 4a of the diaphragm pump 4, a photosensor comprising photoelectric elements 8 is irradiated in a slit 4b and the speed of the movement of the driving shaft 4a at a constant stroke is detected based on the time passing through the slit 4b, and the discharge quantity of the coating material in a cycle of the diaphragm pump 4 is thus calculated by a computing circuit. Based on the discharge quantity of the coating material, a solenoid valve 9 is controlled by a control box 7 and the quantity of the coating material is controlled through an air operated valve 10.

Description

Detailed Description of the Invention

[0001]

[Field of Industrial Application] The present invention relates to paint viscosity control of a paint supply device for adjusting and maintaining the viscosity of paint supplied to a coating machine at a constant level.

[0002]

2. Description of the Related Art In a painting operation, control of the viscosity of a paint supplied to a painting machine is an important factor for keeping the coating quality of the painting constant. When the paint viscosity changes, the amount of paint sprayed by a spray gun or the like and the atomization of spray paint change, which causes a problem that the coating thickness and the quality of the coating surface are not stable.

In general, the viscosity of paint is controlled by mixing a stock solvent or a diluting solvent with a stock solution of the paint so as to adapt to the coating conditions at the time of preparing a paint, and dropping a simple viscometer or a rotary viscometer. A known viscometer is used to prepare an appropriate viscosity and the mixture is charged into a supply device, or the viscosity is measured in the supply device using the viscometer, and then the coating work is performed. This viscosity control is such that the viscosity is controlled during the work, which is measured by the operator himself at the time of blending or reuse of the standing paint, and the like.

Since the organic solvent type paint contains a large amount of volatile solvent, the viscosity of the paint increases with the lapse of time due to the evaporation of the organic solvent even during the work. Therefore, the viscosity is regularly measured during the work. However, it is not done because of the complexity of work.

Further, for a curtain flow coater for coating a flat object by dropping the paint in a curtain shape and passing under the curtain, and for an object to be hung and sent in a closed coating chamber,
Like a deflo coater that paints by pouring paint, in a coating device that directly collects and reuses excess paint that does not adhere to the object to be coated and drops it in the paint container, the paint that comes in contact with the outside air is collected. Since the paint whose viscosity is high is collected in the paint container, there is a problem that the viscosity of the supplied paint becomes high in a short time. And, the coating method of recovering and reusing is a subject to be popularized in terms of resource saving and environmental protection.

[0006] In a coating device that reuses excess paint, the device that manages the viscosity is equipped with a known viscometer such as a rotary viscometer in the paint supply container and supplies a diluting solvent according to a command from the viscometer. A control circuit for supplying the inside of the container and the inside of the supplying container are agitated and controlled by a mechanical agitator. However, this device has a problem in that the rotational viscometer has a problem in stability of accuracy in long-term use and the cost of the device itself is high. Further, in the case of a curtain flow coater, the above-mentioned automatic management is not performed, but the viscosity is regularly measured to adjust the viscosity, which is a bottleneck in operation.

A shaft moving speed detecting device for a diaphragm pump used in the present invention is a detecting mechanism described in detail in Japanese Patent Application Laid-Open No. 63-61781 "Liquid Pump with Discharge Amount Display" filed by the present applicant. The mechanism has an electric circuit that detects the axial movement speed using a photoelectric element and calculates the reciprocating operation cycle of the diaphragm pump by the detection signal.The purpose is to calculate and display the discharge amount of the diaphragm pump from the operation cycle. It is what

Further, the construction in which the jet pressure is jetted from the jet nozzle by utilizing the discharge pressure of the diaphragm pump into the paint liquid stored in the paint container is described in Japanese Utility Model Publication No. 5-10911, filed by the applicant. It is a well-known technology based on "Paint pressure pump with spray paint agitator", which mainly prevents the precipitation of paint in the paint container by jet agitation without using a mechanical agitator by utilizing the excess paint discharge of the diaphragm pump. It was devised in.

[0009]

SUMMARY OF THE INVENTION The present invention is an apparatus for automatically and constantly supplying the viscosity of a coating material supplied to a coating machine at a constant value in order to improve and stabilize the coating film quality in coating. Is what you are trying to get. The object of the apparatus is to provide a viscosity control apparatus having a low probability of mechanical failure and maintaining a stable performance value at a relatively low cost.

For the above-mentioned purpose, paints having the same paint viscosity are used, and the paint viscosity and the paint from the injection nozzle are maintained under the condition that the paint discharge pressure is kept constant within the viscosity range used in general painting machines. Since it was confirmed that the discharge amount correlates, this correlation is converted to the discharge amount and paint viscosity from the moving speed by detecting the moving speed of the diaphragm pump drive shaft, which is directly related to the discharge amount of the diaphragm pump. Supply control of the paint viscosity adjusting liquid in association with the arithmetic circuit to be set and the preset paint viscosity, and
When supplying a coating solvent and automatically adjusting the coating viscosity, it is intended to achieve the object by utilizing jet agitation in order to make the coating viscosity in the coating container uniform at an early stage.

[0011]

SUMMARY OF THE INVENTION The present invention provides a paint circulation circuit for sucking paint by a diaphragm pump from a paint container that stores paint to be supplied to a painting machine, and then recirculating the paint in the paint container by an injection nozzle. In this device, the diaphragm pump is a reciprocating diaphragm pump driven by compressed air pressure, and the diaphragm pump includes a detection device for detecting the moving speed of the drive shaft, and the control is operated by a signal from the detection device. A control box having a circuit is separately arranged, and the spray nozzle for spraying into the paint is a single-hole fan spray nozzle that stirs the paint stored in the paint container by a spray pressure.
In addition, the paint viscosity control device is provided with a paint solvent supply mechanism that supplies the paint solvent into the circulation circuit by opening and closing the solenoid valve according to a command from the control circuit of the control box.

The detection device for detecting the moving speed of the drive shaft of the diaphragm pump has a photoelectric element or an electromagnetic element attached to the diaphragm pump main body, and the drive shaft, which is the object to be detected, corresponds to the element. It is a detection mechanism with a receiver attached.The signal from the detection device is converted into the cycle time of the diaphragm pump by the arithmetic circuit housed in the control box, and the control range is set in advance by correlating it with the paint viscosity. Compared with the stored cycle time, the detected cycle time becomes longer, and when the paint viscosity control upper limit value is reached, the air solvent is supplied by opening the air operated valve provided in the paint solvent supply circuit. When the cycle time is shortened and the paint viscosity control lower limit is reached, an electric control circuit that has an electric control circuit that closes the air operated valve is closed. Box is a paint viscosity adjusting apparatus disposed.

Further, an air operated valve operated by air supplied through a solenoid valve attached to the control box side to a paint solvent supply passage supplied to the circulation circuit, and a solvent tank side of the air operated valve. In the flow path of
It is a paint viscosity control device in which a needle valve capable of finely adjusting a small amount of paint solvent is arranged.

Further, a branch flow path is provided on the discharge side of the diaphragm pump of the paint circulating circuit which circulates by the diaphragm pump, and the viscosity adjusted paint is directly supplied to the coating machine such as a spray gun by a manual or automatic switching mechanism. The diaphragm pump of the paint viscosity control device is a paint viscosity control device that can have both the paint viscosity control function and the paint supply function to the coating machine.

[0015]

The operation of the paint viscosity control apparatus will be described with reference to the schematic diagram of the overall configuration of the present invention shown in FIG. A diaphragm diaphragm pump (4) sucks paint stored in a paint container (1) through a suction pipe (3), and a driven diaphragm pump driven by compressed air adjusted by an air pressure adjuster (17). In (4), the paint pressure is the same as the driving air pressure. The discharged paint is stored in the paint container (1) from a spray nozzle (6) attached to the tip of the paint pipe through a paint circulation circuit (5) consisting of a paint pipe that is relatively thick and has little flow resistance. Spray into the paint and stir the jet. A slit (4b) for detecting the moving speed of the drive shaft (4a) of the diaphragm pump (4) is provided.
In b), an optical sensor consisting of a photoelectric element (8) is irradiated, the moving speed of the drive shaft is detected by the passing time of the slit in a constant stroke, and the arithmetic circuit calculates the discharge amount of the paint per cycle of the diaphragm pump. It The electric circuit which operates by the signal detected by the photoelectric element (8) is arranged in a control box (7) provided separately.

In the control box (7), the correlation between the paint viscosity and the ejection amount from the injection nozzle (6), that is, the paint ejection amount of the diaphragm pump under the condition that the injection nozzle (6) is attached is taken. , The correlation is stored in advance as the moving speed of the drive shaft. Then, when the paint viscosity increased and the moving speed of the drive shaft of the diaphragm pump (4) slowed down, the paint viscosity reached the upper limit of the set value range by comparison with the stored correlation value with the paint viscosity. At this time, a command is transmitted to the 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 branched and provided on the suction pipe (3) side of the diaphragm pump (4). The air operate valve (10) has a solvent tank (11) for storing a paint solvent for adjusting the paint viscosity.
And the paint solvent supplied from the solvent tank (11),
An adjustable needle valve (12) is connected for dispensing small doses. The paint solvent is supplied by an open-type container that is sucked by the suction force of the diaphragm pump (4), or by a method such as a paint tank, which is pressurized and pressure-fed and supplied at a constant pressure with high accuracy. Further, the adjustment of the needle valve (12) is for adjusting in advance the amount of the liquid to be supplied in small amounts in accordance with the increasing rate of the viscosity of the paint. Therefore, the needle valve (12) controls the amount of paint that adjusts the coating conditions of the coating device,
Once adjusted by the viscosity, etc., it remains open.

In the above construction, when the viscosity of the paint increases and the moving speed of the drive shaft of the diaphragm pump slows down to reach the preset upper limit viscosity value, a command is issued and the solenoid valve (9) is opened to open the air. The air-operated air-operated valve (10) is opened, and the coating solvent is supplied little by little through the needle valve (12). When the paint whose solvent has been supplied and the viscosity of which has been lowered is sucked into the diaphragm pump, the moving speed of the drive shaft of the diaphragm pump increases. The moving speed has become faster,
When reaching the lower limit of the preset paint viscosity range,
The control circuit is activated and the solenoid valve (9) is closed and the air operated valve is closed. When the paint having a low viscosity containing the paint solvent is jet-stirred with the paint stored in the paint container (1) to be uniformized by the paint circulation, the viscosity is increased again and the paint is sucked into the diaphragm pump, The control circuit operates, the solenoid valve (9) is opened again, and the same operation as the above is repeated. In this way, the paint solvent is adjusted in a decay curve by repeating the intermittent supply, and is adjusted by repeating until the paint viscosity stabilizes within the preset viscosity range.

The injection nozzle (6) is easily worn by the paint pigment contained in the paint. If the injection nozzle (6) is worn and the ejection amount of the injection nozzle is different, an error occurs in the correlated viscosity range preset and stored in the control box. Therefore, the injection nozzle that is circulated and ejected for a long period of time must have low wear. The injection nozzle (6) is made of a super hard material such as tungsten carbide, and a single-hole fan spray nozzle that spreads in a slightly conical or fan shape is used in order to enhance the jet stirring efficiency.

The branch passage ((13) of the paint circulating circuit (5), which is branched to the discharge side of the diaphragm pump, is a paint circulating circuit when the paint viscosity is stably adjusted within the set viscosity range by the paint viscosity management device. The ball valve (17) of the ball valve (1) connected to the branch passage (13) is closed.
4) is opened, and the paint regulator (15) is used to adjust the pressure of the paint to an appropriate value so that the paint can be supplied to a painting machine such as a spray gun. The purpose of this mechanism is to reduce the equipment cost by also using the paint supply pump in the case of relatively intermittent small-scale painting. In the case of a large amount of continuous coating, it is supplied by using a separate paint supply pump, and the paint viscosity control device is installed in a constantly operating state exclusively for viscosity control.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the schematic diagram of the overall configuration of FIG. However, in principle, the parts explained in the section of action are omitted. The paint container 1 is not particularly limited, but a paint container of about 20 liters is usually used. However, in the above-mentioned system coating machines such as the flow coater and the deflo coater, the paint container is manufactured exclusively. A suction filter 2 is attached to the tip of the suction pipe 3 as far as the bottom of the paint container 1 to prevent dust from entering the paint circulation circuit and clogging of the injection nozzle 6. The suction pipe 6 is connected by a flexible paint hose in the middle of the flow path so that it can be arranged according to the length and position to the bottom of the paint container. On the diaphragm pump side of the suction pipe 3, a paint solvent supply port is diverged with a T-shaped joint. An air operate valve 10 is connected to the paint solvent supply port. The air operated valve 10 is a valve having a known valve mechanism that operates by operating the air pressure from the three-way solenoid valve 9 by an air piston or a diaphragm. The needle valve 12 connected to the air operated valve 10 is also a manually-known general well-known valve having a finely adjustable needle valve. The solvent tank 11 is attached with a ball valve 19 required when the solvent tank 11 is removed, and is always open when set. The paint solvent in the solvent tank 11 is supplied by the suction force of the diaphragm pump, but as described above, the paint solvent may be stored in a pressure supply tank or the like (not shown) and pressure-fed and supplied.
The above-mentioned coating solvent supplying means is not a limitation of the present invention.

The return type diaphragm pump 4 has a drive shaft 4
a is reciprocated left and right by compressed air of about 500 kPa regulated by the air pressure regulator 18, and the diaphragms 4c directly attached to the drive shaft 4a are alternately bent to suck the intake valves in the paint chambers 4d on both sides. , Pumping by pressurizing and sucking through the discharge valve. The paint pressure is about 500 kPa, which is the same as the compressed air pressure. The paint circulation pump of the present invention has a pressure ratio of 1:
The reason for using the diaphragm pump of No. 1 is that the pump drive pressure and the paint discharge pressure are precisely controlled at the same pressure,
For example, when a gear pump or a plunger pump with a high pressure ratio is used, if the paint viscosity of the paint circulation circuit increases and the flow path resistance of the circuit increases, the pressure in the circulation circuit inevitably increases. Since it works so as to increase the ejection amount from the ejection nozzle, there is a drawback that the correlation between the ejection nozzle and the paint viscosity cannot be obtained. Therefore, the paint circulation circuit of the present invention has a sufficient flow path diameter of the paint circulation circuit with respect to the ejection amount of the injection nozzle, and even if the paint viscosity increases in the paint viscosity range adapted for painting. The flow path resistance of the circulation circuit has a thickness that does not directly affect the ejection amount from the ejection nozzle.

As for the moving speed of the drive shaft 4a, several slits 4b are bored at the same intervals at substantially the center of the drive shaft 4a.
The photoelectric element 8 is irradiated with the light, the number of slits passing through the slit is received per unit time, and the cycle time is calculated by the arithmetic circuit in the control box. Since a similar effect can be obtained even if a magnetic body is attached to the drive shaft instead of the slit and the electromagnetic element receives the same, it is a photoelectric element or an electromagnetic element.

Pump chamber 4 of the return type diaphragm pump 4
The paint that is alternately and substantially uniformly discharged from d is sprayed from the spray nozzle 6 through the circulation circuit 5, but the paint pipe of the circulation circuit 5 uses a partially flexible paint hose and the spray position and the like. Can be adjusted. The spray nozzle 6 detachably attached to the tip of the paint pipe forms a conical or fan-shaped pattern parallel to the bottom surface or slightly toward the bottom surface as close to the bottom of the paint container 1 as possible. It is sprayed with a single-hole fan spray nozzle. This injection direction is
Depending on the shape of the paint container, etc., the position and the angle are adjustable in order to prevent sedimentation on the bottom of the paint container and more effectively jet agitate the stored paint in the paint container.

A branch passage 13 is provided in the paint circulation circuit 5, and when the paint viscosity becomes stable, the ball valve 17 of the paint circulation circuit 5 is closed, the ball valve 14 of the branch passage 13 is opened, and the paint regulator 15 is used. A dual-purpose circuit for adjusting the pressure of the paint and supplying it to the spray gun 19 is provided to supply the paint. When supplying paint to a spray gun, etc., proper viscosity control cannot be performed in the control box. Therefore, when the paint is supplied to the spray gun or the like, the function is stopped after the control box is manually operated or the function is stopped by the switch which operates in conjunction with the coating machine such as the spray gun. Further, since the jet agitation of the jet nozzle 6 can be jetted by utilizing the surplus power of the diaphragm pump, when the paint usage of the painting machine is smaller than the discharge capacity of the diaphragm pump, the paint circulation circuit is used. It is also possible to continue jet agitation without completely closing the ball valve 17 of No. 5.

[0026]

As described above, since the amount of paint sprayed from the spray nozzle correlates with the viscosity of the paint, the paint in the paint container is made into a paint circulation circuit by using a double-acting diaphragm pump, By using a paint viscosity management device that has a control circuit that detects the drive shaft movement speed and supplies the paint solvent to adjust the viscosity, it is possible to manage paint viscosity with high accuracy and reduce the probability of mechanical failure. By supplying a paint having a stable viscosity, it is possible to obtain an effect that enables high-quality coating.

By using the jet agitation from the injection nozzle as the agitation of the paint, a paint viscosity control device capable of preventing the paint precipitation and precipitating the paint viscosity at a low cost without using a mechanical agitator.

The control circuit for supplying the paint solvent for adjusting the viscosity directly controls the drive shaft moving speed signal of the diaphragm pump to adjust the adjustment of the paint viscosity in a damping curve. Without using, it is possible to adjust viscosity with high accuracy with a relatively simple control circuit.

Since the diaphragm pump for circulating the paint for controlling the viscosity of the paint can also be used as the pump for supplying the paint to the coating machine, the effect of being able to provide the paint supplying device capable of automatically controlling the viscosity of the paint at a low cost is obtained. is there.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a viscosity control device of the present invention.

[Explanation of symbols]

 1 Paint Container 3 Suction Pipe 4 Diaphragm Pump 5 Paint Circulation Circuit 6 Injection Nozzle 7 Control Box 8 Photoelectric Element 9 Electromagnetic Valve 10 Air Operated Valve 11 Solvent Tank 12 Needle Valve 13 Branch Path 14, 17, 19 Ball Valve 18 Air Pressure Adjustment vessel

Claims (5)

[Claims] 1. A device having a paint circulation circuit for sucking paint by a diaphragm pump from a paint container for storing paint to be supplied to a coating machine, and again injecting the paint back into the paint in the paint container by means of an injection nozzle, wherein the diaphragm pump is A return type diaphragm pump driven by compressed air pressure, the diaphragm pump having a detection device for detecting the moving speed of the drive shaft, and a separate control box having a control circuit operated by a signal from the detection device. The spray nozzle for spraying the paint into the paint is a single-hole fan spray nozzle that stirs the paint stored in the paint container by spraying pressure, and the paint solvent is introduced into the paint circulation circuit in the control box. Paint viscosity tube with a paint solvent supply mechanism that opens and closes the solenoid valve to supply it in response to commands from the control circuit Equipment. 2. A signal of a detection device for detecting the moving speed of a drive shaft of a diaphragm pump is converted into a cycle time of the diaphragm pump by an arithmetic circuit housed in a control box, and the viscosity of the paint is correlated with the viscosity of the paint in advance. When the detected cycle time becomes longer than the cycle time in which the control range is set and stored, and the paint viscosity control upper limit value is reached, the air operate valve provided in the paint solvent supply circuit is opened to open the paint solvent. The paint viscosity control device according to claim 1, wherein the air operation valve is closed when the cycle time is shortened and the control lower limit value of the paint viscosity is reached. 3. An air operated valve operated by air supplied through a solenoid valve attached to a control box side to a paint solvent supply flow path supplied to a circulation circuit, and a solvent tank side of the air operated valve. The paint control device according to claim 1, wherein a needle valve capable of finely adjusting a small amount of paint solvent is disposed in the flow path of the above. 4. A photoelectric element attached to the pump body for detecting the moving speed of the drive shaft of the diaphragm pump, or
The paint viscosity detecting device according to claim 1, wherein the paint viscosity detecting device is an electromagnetic element, and a receiving mechanism is attached to a drive shaft, which is an object to be detected, according to the element. 5. A branch passage is provided on the diaphragm pump discharge side of a paint circulation circuit that circulates with a diaphragm pump, and the paint whose viscosity is adjusted is directly supplied to a coating machine such as a spray gun by a manual or automatic switching mechanism. 2. The paint viscosity management device according to claim 1, wherein the diaphragm pump of the paint viscosity management device has a paint viscosity management function and a paint supply function to the coating machine.