JPH0510948Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a coating agent flow rate control device, and more specifically, the present invention relates to a coating agent flow rate control device, and more specifically, a coating agent flow rate control device that constantly predetermines the amount of coating agent supplied from a coating agent supply source to a coating machine. It also relates to a device for controlling the amount to a constant level.

<Conventional technology> For example, in painting work, it is used for quality control purposes to prevent uneven coating on objects to be painted and to create an aesthetic appearance, and from a resource-saving standpoint to prevent overpainting and reduce the amount of paint used. Therefore, it is desirable to maintain a constant coating film thickness on the object to be coated, and therefore, it is required to maintain and control the amount of paint supplied from the paint supply source to the coating machine at a constant, predetermined amount at all times. Ru. Therefore, conventionally, various methods have been adopted, such as using a fixed-capacity pump as a paint supply pump, or maintaining a constant supply pressure of paint supplied from a paint supply source to a coating machine.

However, with these conventional methods, usually multiple paint sprayers are used for one paint supply pump in painting work, and when multiple paint sprayers are used, each paint sprayer is supplied with paint. The internal resistance of the supply pipe that supplies the paint varies, and even if the paint supply pressure is maintained constant, a constant amount of paint will not necessarily be supplied to each paint sprayer, and the internal resistance of the supply amount is The viscosity of the paint changes from time to time due to the usage conditions of the paint sprayer and how bent the supply pipe is, and also due to temperature changes throughout the year and temperature changes in the morning, afternoon, and evening of the day. Due to the combination of various conditions, such as the fact that the amount of paint supplied increases or decreases considerably due to changes, it has not been possible to obtain a satisfactory paint supply state.

In addition, in order to cope with changes in viscosity due to temperature, a method is adopted in which the paint supply pressure is selected in stages according to the temperature at that time. It cannot respond to changes in paint supply amount due to other causes such as clogging.

Therefore, in view of the above-mentioned situation, the present inventors proposed a method using ultrasonic waves to control the flow rate of the coating agent supplied from the coating agent supply source to the coating machine, as shown in Utility Model Application Publication No. 58-53276. Flow rate control installed between the coating material supply source and the coating machine A device that controls the flow rate of a coating agent by adjusting the opening degree of a valve has already been proposed. In this device, as a coating material flow rate detection method using ultrasonic waves, for example, ultrasonic waves are emitted from an oscillator toward the inside of the coating material feeding pipe, and the reflected waves are sensed by a receiver, and the oscillated waves and A method is adopted in which the difference in frequency of reflected waves is measured and the flow rate of the coating material is determined from this frequency difference based on the Doppler effect.

<Problems that the invention aims to solve> However, ultrasonic flow rate detection means generally have excessively sensitive flow rate detection sensitivity, and therefore often detect changes in the flow rate of the coating agent more delicately than necessary. . Furthermore, since this detection means is sensitive to foreign matter in the coating agent, it may produce erroneous detection results. Therefore, in the above-mentioned flow rate control device, the opening degree of the flow rate control valve tends to change unnecessarily rapidly, and the control valve may open and close incorrectly, making it difficult to always supply a constant amount of coating material accurately. There was a problem above. Even if the above-mentioned control device is equipped with a switching mechanism that appropriately switches on and off the signal for changing the opening degree of the flow control valve, there is a possibility that these technical problems cannot be completely resolved.

The purpose of this invention is to eliminate the above-mentioned technical problems and to maintain the amount of coating agent supplied from the coating agent supply source to the coating machine at a constant, predetermined amount regardless of changes in various coating conditions. The goal is to provide equipment that can be maintained and controlled.

Another purpose of the present invention is to detect the flow rate of the coating agent without contacting it and to control the supply (spray) of the coating agent.
It is an object of the present invention to provide a device that can maintain and control the supply amount of a coating agent at a predetermined constant amount without causing malfunction even when ON-OFF control is performed.

<Means for solving the problem> However, according to the present invention, the flow rate of the coating agent is detected by using the characteristics of the sound of the coating agent being fed from the coating agent supply source to the coating machine, and the flow rate is determined. A flow rate detection unit outputs a signal according to the flow rate, and the signal from the flow rate detection unit is compared with a predetermined reference signal, and the signal level from the flow rate detection unit does not reach or exceeds the allowable level of the reference signal. a signal comparison section that outputs a signal corresponding to the signal, and an opening degree of a coating material flow control valve that is operated by the signal from the signal comparison section and is interposed between the coating material supply source and the coating machine. a valve opening adjustment mechanism that adjusts the valve opening adjustment mechanism, and is interposed between the signal comparison section and the valve opening adjustment mechanism, and is configured to intermittent the signal transmitted from the signal comparison section to the valve opening adjustment mechanism using a predetermined signal. A coating agent flow rate control device is provided, characterized in that it is equipped with a switching mechanism.

The "predetermined signal" in the switching mechanism of the device of the present invention refers to the "predetermined signal" in the switching mechanism that is used to stop transmitting the signal from the signal comparison section to the valve opening adjustment mechanism for a certain period of time when starting or stopping the supply of coating material. It is a signal that operates in synchronization with the ON-OFF control signal for supplying the coating agent.

In this case, “operating synchronously” means ON-OFF control of coating material supply (or control of coating machine operation).
In addition to cases in which the device works at the same time as the moment when the operation turns ON and OFF, it also includes cases in which it works a little later than the moment when the operation turns ON and OFF.

Furthermore, the control signal for coating agent supply emitted from the coating agent supply source may be taken in as it is without being processed and used as a "predetermined signal," but alternatively, the control signal may be passed through a delay circuit, etc. , processed into a form with a certain time lag relative to the control signal,
This can also be used as a "predetermined signal". Furthermore, instead of such a control signal, it is also possible to use an operation ON/OFF control signal that acts on the coating machine itself.

Therefore, the switching mechanism does not operate while the coating agent is being supplied normally, but when the coating agent supply starts or stops due to ON/OFF operation of the coating machine, the switching mechanism does not operate as described above. The signal from the signal comparator is cut off based on the "signal", and this signal is prevented from being transmitted to the valve opening adjustment mechanism for a certain period of time.

<Function> In other words, the coating agent flow rate control device according to the present invention constantly monitors the flow rate of the coating agent supplied to the coating machine, and if the flow rate deviates from a predetermined flow rate, it immediately activates the flow control valve. This is a device that corrects the flow rate by adjusting the opening degree of the valve. This device adopts a method of detecting the flow rate of the coating agent using the characteristics of the flow sound of the coating agent, such as the frequency and amplitude, and the detection sensitivity of the flow rate is sharp at an appropriate level. Furthermore, it is not overly sensitive to foreign substances in the coating agent. Therefore, in the device of the present invention, the opening degree of the flow rate control valve can be appropriately adjusted without changing too sensitively, and there is no risk of the control valve malfunctioning due to the purity or composition of the coating agent.

Furthermore, the control device of the present invention is a device that detects the flow rate of the coating agent based on the characteristics of its flow sound, that is, in a non-contact manner. Therefore, the detection area is not attacked by the coating agent.

Furthermore, during coating work, the coating agent supply (spray) is normally controlled on and off, and the flow rate flowing into the coating machine fluctuates in a pulsed or pulsating manner, and the flow rate detection signal also fluctuates accordingly. The device uses a switching mechanism that operates synchronously with the coating agent supply ON-OFF control signal to cut out detection signals that interfere with flow rate control, so the coating agent supply can be controlled ON-OFF. It is possible to maintain and control the supply amount of the coating agent at a predetermined constant amount without causing any malfunction.

The flow rate detection unit used in the present invention can detect the characteristics of the sound of the coating agent flowing there, such as the frequency The flow rate and amplitude are measured by the sonic sensor, and then the flow rate of the coating material is determined by comparing the flow sound characteristics measured in the main body of the detection unit with the flow sound characteristics at each flow rate stored in advance. It is configured to output a signal according to the In this case, a bench lily section or the like is provided in the middle of the supply path, and a sonic sensor is arranged at or near the bench lily section, and the flow of the coating agent that occurs when the coating agent passes through the bench lily section and forms a turbulent flow. It is more preferable to measure the characteristics of the sound using the sonic sensor, since the change in the characteristics of the flow sound with respect to the flow rate becomes more noticeable. Alternatively, the detection unit body and the sonic sensor may be integrated into one, but in practice, it is possible to separate and connect multiple sonic sensors to one detection unit body via a distributor. It is preferable.

Further, the reference signal may be a fixed signal set in advance, but in practice it is desirable that it be a signal that can be varied stepwise or steplessly so that an arbitrary supply amount can be easily set at any time.

As the valve opening adjustment mechanism in the present invention, a pulse motor drive mechanism, an electro-pneumatic conversion drive mechanism, etc. are preferably adopted.

<Example> The present invention will be described in detail below based on an example.

FIG. 1 is a flowchart (system diagram) showing an example of the case where the device of the present invention is applied to an electrostatic coating device. Via electrostatic coating machine 5
is supplied to A three-way valve 6 is connected in the middle of the paint supply path 4, and the paint 2 supplied from the paint supply pump 3 is switched and supplied to either the paint supply path 4 or the paint circulation path 7. A back pressure valve 8 is connected in the middle of the paint circulation path 7, and is adjusted so that the load applied to the paint supply pump 3 does not change much when the three-way valve 6 is switched and used. Since there is a risk that high voltage may be leaked and applied to the three-way valve 6 from the electrostatic atomizer 5 via the paint supply path 4, the three-way valve 6 is turned on by compressed air from the compressed air supply source 9. It is electrically insulatedly operated via a solenoid valve 11 by an electric signal from an OFF control section 10. It goes without saying that if there is no risk of high voltage being applied to the three-way valve 6, the three-way valve 6 may be operated directly electrically. Further, in the middle of the paint supply path 4, there is a flow control valve 12 for adjusting and controlling the amount of paint 2 supplied to the electrostatic atomizer 5.
is provided so that the amount of paint 2 supplied can be accurately controlled by adjusting the opening degree of the valve.

As shown in FIG. 2, a bench lily section 13 is provided in the middle of the paint supply path 4, and a sonic sensor 14 is installed in the supply path slightly downstream of the bench lily section 13, as shown in FIG. (In some cases, it is attached to the outside of an electrically insulating material such as polyethylene pipe). The paint 2 flows from the supply tank 1, passes through the bench lily part 13, forms a turbulent flow 15, and then flows toward the coating machine 5, at which time a flow noise corresponding to the flow rate is generated. The sonic sensor 14 measures the characteristics of this circulating sound, such as the frequency and amplitude, and sends the information to the detecting unit main body 16 connected to the sensor 14, and the detecting unit main body 16 measures the measured circulating sound characteristics in advance. The flow rate of the paint 2 flowing through the paint supply path 4 is accurately detected by comparing with the same characteristics at each flow rate stored, and an electric signal corresponding to the detected flow rate is output. When detecting the flow rate of paint flowing into multiple paint supply paths with one detection unit main body 16, a distributor (not shown) is connected between the detection unit main body 16 and the sensor 14, and the distribution A large number of sensors 1
4 can be connected to perform detection sequentially.

The flow rate detection signal output from the flow rate detection unit main body 16 is compared with a reference signal from the paint supply amount setting unit 17 in a signal comparison unit 18, and when the flow rate detection signal level does not reach or exceeds the allowable level of the reference signal, When this happens, the signal comparator 18 outputs a corresponding electrical signal. The reference signal from the paint supply amount setting section 17 can be varied stepwise or steplessly, so that the paint supply amount can be arbitrarily set at any time. The paint supply amount can also be set by changing the level of the reference signal as described above, but it is also possible to set the reference signal as a fixed signal or a semi-fixed signal and to vary the amplification or attenuation rate of the flow rate detection signal. This can also be done by doing the following: When comparing the flow rate detection signal and the reference signal in the signal comparison section 18, analog signals may be compared, but usually both signals are converted into digital signals and then compared.

The signal output from the signal comparison section 18 is transmitted to the valve opening adjustment mechanism 20 via the switching mechanism 19, and the valve opening adjustment mechanism 20 operates, thereby adjusting the opening of the flow rate control valve 12. , the flow rate (supply amount) of the paint 2 flowing through the paint supply path 4 is automatically corrected and controlled so that it becomes a predetermined value. Since there is a risk that high voltage may leak and be applied to the flow rate control valve 12 from the electrostatic coating machine 5 via the paint supply path, the flow rate control valve 12 is made of an electrically insulating material (for example, Delrin, etc.).
It is operated in an electrically insulating manner using a shaft made of electrically insulating material such as FRP) and compressed air. Flow control valve 1
If there is no risk of high voltage being applied to 2,
Of course, the flow control valve 12 may be operated directly electrically. Further, it is also possible to configure the flow rate control valve 12 and the valve opening adjustment mechanism 20 integrally, and furthermore, they can be incorporated into the coating machine. It is desirable that an alarm be issued if the flow rate (supply amount) by the flow rate control valve 12 exceeds the correction control range or if control becomes impossible.

In addition, during painting work, it is common practice to control the spraying of paint on and off by spraying paint from the paint sprayer and stopping the spraying depending on the shape of the object to be painted and the purpose of painting. Yes, in this embodiment, the paint ON-OFF control section 10
The needle valve (not shown) in the electrostatic sprayer 5 and the three-way valve 6 are operated in response to a signal from the electrostatic sprayer 5, and the flow direction of the paint is switched, thereby controlling the spraying of the paint on and off. Therefore, the flow of paint flowing through the paint supply path 4 fluctuates in a pulsed or pulsating manner, and the flow rate detection signal from the detection section body 16 that detects the flow also fluctuates accordingly. If the valve opening adjustment mechanism 20 is operated each time due to signal fluctuations that are essentially unrelated to actual flow rate changes, the operation time lag of the valve opening adjustment mechanism 20 (a predetermined time lag after receiving the command signal) Since it is not possible to stably supply a constant amount of paint to the electrostatic coating machine 5 due to the time it takes to adjust the flow rate control valve 12 to the opening degree, the present invention adopts the method shown in this embodiment. , a switching mechanism 19 that is interposed between the signal comparator 18 and the valve opening adjustment mechanism 20 and operates synchronously with the paint ejection ON-OFF control signal, detects the signal that interferes with flow rate control. It cuts out the fluctuations. That is, when a signal to stop spraying paint is transmitted from the paint ON-OFF control unit 10 to the needle valve and solenoid valve 11 in the electrostatic sprayer 5, the signal is simultaneously transmitted to the switching mechanism 19, and the switching mechanism 19 is a signal comparison unit 18 and a valve opening adjustment mechanism 20
Since the circuit between the valve opening adjustment mechanism 20 and the valve opening adjustment mechanism 20 is opened, the signal from the signal comparison section 18 is not transmitted to the valve opening adjustment mechanism 20. Therefore, the ejection of paint is stopped, the flow rate detection signal indicates that the flow rate flowing through the paint supply pipe 4 is 0, and a command signal is sent from the signal comparator 18 to increase the opening degree of the flow rate control valve 12. Even if the signal is output, the signal is not transmitted to the valve opening adjustment mechanism 20, so the valve opening adjustment mechanism 20 does not operate, and the opening of the flow control valve 12 is maintained as before. Next, when a signal to start spraying the paint is issued from the paint ON-OFF control unit 10, the signal is transmitted to the electrostatic paint sprayer 5.
The signal is transmitted to the needle valve and electromagnetic valve 11 within the valve, and at the same time is transmitted to the switching mechanism 19 via the delay circuit 21 after a certain period of time has elapsed. That is, the needle valve of the electrostatic atomizer 5 opens, the solenoid valve 11 operates, and the three-way valve 6 is operated, and after the supply of paint is started, the paint starts to flow steadily in the paint supply path 4. Since it takes a certain amount of time (time lag) for the switching mechanism 19 to turn on and off, the operation of the switching mechanism 19 is delayed by a delay circuit 21 interposed between the paint ON-OFF control section 10 and the switching mechanism 19.
After the paint starts to flow steadily in the paint supply path 4, the switching mechanism 19 is operated to close the circuit between the signal comparator 18 and the valve opening adjustment mechanism 20. Therefore, the valve opening adjustment mechanism 20 is not affected by fluctuations in the flow rate detection signal at the start of paint ejection. Delay circuit 21
As described above, the paint jet stop signal is immediately transmitted to the switching mechanism 19, and the paint jet start signal is transmitted to the switching mechanism 19 after a certain delay time has elapsed. As the switching mechanism 19, a semiconductor such as an SCR is preferably used in addition to a normal electromagnetic relay. Note that if a delay relay is used as the switching mechanism 19, the delay circuit 21 is not necessary.

Using the equipment described above, we conducted experiments with various paints, such as organic solvent-based paints, water-based paints, and metallic paints, by setting the paint supply amount each time. Despite various changes in coating conditions, such as fluctuations in paint supply pressure and paint supply pressure, it was possible to maintain and control the paint supply amount at a constant level at all times.

In addition, the device of the present invention can be applied to various electrostatic and non-electrostatic coating devices such as air atomization, hydraulic atomization, centrifugal force atomization, and static atomization, as well as oil application devices and humidification devices. Furthermore, it can be applied to various supply devices for surface treatment liquids, various chemical solutions, suspensions of graphite powder, etc., inks, dyes, and the like.

<Effects of the invention> The coating agent flow rate control device of the present invention is capable of controlling and maintaining the supply amount of coating agent supplied to the coating machine at a predetermined constant amount at all times despite changes in various coating conditions. By adopting a method that uses flow sound characteristics to detect flow rate, it is possible to control the supply amount of coating material with more appropriate flow detection sensitivity and accuracy than with conventional methods that use ultrasound. can. In addition, there is no obstruction to the flow of the coating agent or erosion of the flow rate detection part, and in addition, it is easy to supply the coating agent.
Even if ON-OFF control is performed, incorrect flow rate control will not occur. Furthermore, the flow rate detection means that measures the characteristics of sound is much cheaper than the same means that emits and senses ultrasonic waves, so the overall cost of the device of the present invention is significantly lower. Become something.

[Brief explanation of the drawing]

Fig. 1 is a flowchart (system diagram) showing a coating agent flow rate control device according to an embodiment of the present invention to which an electrostatic coating device is applied, and Fig. 2 shows a paint supply path in which a sonic sensor of the device shown in Fig. FIG. In the figure, 1...paint tank, 4...paint supply path,
5... Electrostatic coating machine, 12... Flow rate control valve, 14...
...Sonic wave sensor, 16...Detection unit main body, 17...Paint supply amount setting section, 18...Signal comparison section, 19...
Switching mechanism, 20... Valve opening adjustment mechanism.

Claims (1)

[Scope of utility model registration request] A flow rate detection unit 1 detects the flow rate of the coating agent using the characteristics of the flow sound of the coating agent fed from the coating agent supply source to the coating machine 5 and outputs a signal according to the flow rate.
4, 16, and the signals from the flow rate detection units 14, 16 are compared with a predetermined reference signal, and when the signal level from the flow rate detection units 14, 16 does not reach or exceeds the allowable level of the reference signal. a signal comparison section 18 that outputs a signal corresponding to the signal; and a coating agent flow rate control valve 12 that is operated by the signal from the signal comparison section 18 and is interposed between the coating agent supply source and the coating machine 5. a valve opening adjustment mechanism 20 that adjusts the opening of the valve;
A switching mechanism 19 is interposed between the signal comparison section 18 and the valve opening adjustment mechanism 20, and switches on and off the signal transmitted from the signal comparison section 18 to the valve opening adjustment mechanism 20 according to a predetermined signal. A coating agent flow rate control device comprising: