JPH035225B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a flow rate control method for feeding a viscous fluid in a fixed amount, and is capable of constantly feeding a constant flow rate even if the viscosity changes due to temperature changes. The purpose is to provide a flow rate control method.

Conventional Technology Conventionally, when applying a high viscosity fluid, such as an adhesive sealing material (hereinafter referred to as "sealer"), to the panel joints of an automobile body, a coating device such as a robot equipped with an automatic coating gun is used to apply the coating automatically. The coating was applied by moving the nozzle tip of the gun along the panel seams and turning the coating gun on and off depending on the area that required sealing.
In this case, a plunger pump or the like driven by compressed air is used to feed the sealer, which is a viscous fluid, and a high-pressure hose is connected between the pump and the automatic coating gun, and the sealer is normally fed at a predetermined pressure. .

Problems to be Solved by the Invention In the conventional method described above, when the viscosity of the sealer changes due to changes in the outside temperature, the pressure loss inside the hose and the application gun changes, and the discharge flow rate of the sealer changes. There was a problem that the sealer application width, that is, the sealing quality was not stable. In order to solve this problem, the current situation is that workers frequently adjust pressure regulators and the like in accordance with changes in temperature to artificially stabilize the flow rate. In addition, as another solution, a method has been devised to ensure a constant flow rate by operating at a constant speed using a constant displacement pump, but due to the pressure accumulation effect of the hose, the dispensing gun
It takes a long time for the sealer discharge amount to reach the specified flow rate when ON, and the time to reach the specified flow rate changes depending on the temperature (approximately ±20%). ) to perform highly efficient sealing work, the sealer application width may not be stable at the start of application (application distance
400 to 500 mm or more) remains a problem.

Means for Solving the Problems In order to solve the above problems, the method of the present invention provides a method for supplying viscous fluid under pressure to an on-off type coating gun using a constant volume pump, in which the viscous fluid is pumped from the coating gun. In the off state when no discharge is being performed, the temperature and pressure of the viscous fluid in the hose connecting the constant displacement pump and the coating gun are detected, and the desired set flow rate is determined at the detected temperature based on preset temperature-supply pressure characteristic data. Calculate the supply pressure to obtain the viscous fluid, compare the calculated supply pressure with the detected pressure of the viscous fluid, and control the discharge pressure of the constant displacement pump so that the detected pressure matches the supply pressure. When the viscous fluid is being discharged from the coating gun in the on state, the constant displacement pump is operated at a constant speed that provides a desired set flow rate.

The above control method uses a temperature sensor that detects the temperature of the viscous fluid in the hose connecting the constant displacement pump and the coating gun, a pressure sensor that also detects the pressure of the viscous fluid in the hose, and a preset temperature-supply. pressure calculation means for calculating a supply pressure for obtaining a target set flow rate at the temperature of the viscous fluid detected by the temperature sensor from pressure characteristic data; a supply pressure signal that is applied by the pressure calculation means when the coating gun is turned off; means for controlling the discharge pressure of the constant displacement pump so that the detected pressure of the pressure sensor matches the supply pressure obtained by the pressure calculating means by comparing the pressure detection signal of the pressure sensor; and when the coating gun is turned on. This is carried out by means of operating the constant displacement pump at a constant speed set in advance to provide a desired set flow rate.

Embodiments and their functions FIG. 1 shows an example of an apparatus for carrying out the method of the present invention. Sealer 1 in a tank, which is a viscous fluid, is sucked into a constant displacement pump 3 through a pipe 2, and then pumped through a hose 4. It is supplied under pressure to the coating gun 5. on the other hand,
The constant displacement pump 3 is driven by a servo motor 6, and a speed detector 7 is connected to the servo motor 6. The servo motor 6 and the speed detector 7 are connected to a control unit 10 by wires 8 and 9, respectively. ing. Further, a temperature sensor 11 for detecting the temperature of the sealer inside the hose and a pressure sensor 12 for detecting the pressure of the sealer are attached to the hose 4, and are configured to send detection signals to the control unit 10 through wirings 13 and 14, respectively. has been done. Also,
The coating gun 5 operates the solenoid valve 1 in response to ON/OFF control signals sent from the control unit 10 through the wiring 16.
7 and sends an air pilot signal from the air source 15 to the coating gun 5 via the air hose 18.
The coating gun 5 is configured to be turned on and off.

FIG. 2 shows the configuration of the control unit 10,
The target set flow rate Q ₁ and the temperature-supply pressure characteristic data of the sealer 1 (FIG. 4) are input in advance from the setting device 103 and stored in the RAM 101 via the digital input port 104. Temperature sensor 11
The temperature signal and pressure signal detected by the pressure sensor 12 are sent to the A/D converter 105, respectively.
After being converted into a digital signal, it is read into the CPU 100. A control procedure consisting of a flowchart shown in FIG. 3 is stored in advance as a program in the ROM 102, and input and output are controlled via the CPU 100.

The operation control signal for the servo motor 6 output from the CPU 100 is sent to the servo amplifier 107 via the D/A converter 106, and becomes a drive current to rotate the servo motor 6. Note that the signal from the speed detector 7 is sent to the servo amplifier 107 via a relay 109.
The servo motor 6 is connected to the servo motor 6 and is configured to feed back the actual operating speed of the servo motor 6. Also,
The CPU 100 outputs an ON signal for the relay 109 and an ON signal for the coating gun 5, and operates the relay 109 and the solenoid valve 17 via the digital output port 108.

The operation of the method of the present invention carried out by the above-mentioned apparatus will be explained with reference to the flowchart of FIG.

First, when the device is powered on and starts operating, the control unit 10 determines whether the coating gun 5 is ON or not.
Determine whether it is OFF (step).

If coating gun 5 is not turned on, relay 1
09 is turned off (step), then the sealer temperature T ₀ in the hose is read from the temperature sensor 11 (step), and the temperature-supply pressure characteristic data shown in FIG. 4 stored in the ROM 101 and the temperature sensor are read. Based on the detected temperature T ₀ of
Supply pressure that gives the desired set flow rate Q ₁ at T _0
P0 is read (step). Then, based on this supply pressure P ₀ and the fluid pressure P ₁ (step) in the hose 4 detected by the pressure sensor 12, the drive signal V ₀ of the servo motor 6 is set as V ₀ =K(P ₀ −
P ₁ ) is calculated from the calculation formula (K in the formula is a proportionality constant) (step), and the drive movement V ₀ is calculated by the D/A converter 10.
6. Servo motor 6 via servo amplifier 107
Send to (step). As a result, the servo motor 6 is controlled to the driving force that provides the supply pressure P ₀ ,
The constant displacement pump 3 is operated at a rotation speed that generates the pressure P ₀ . Therefore, when the coating gun 5 is in the OFF state, the fluid pressure inside the hose 4 remains at the set flow rate Q ₁ at the target temperature even if the fluid temperature changes.
The pressure is automatically set to give the As a result,
The viscous fluid can be discharged from the nozzle of the coating gun 5 at a predetermined set flow rate Q ₁ immediately after the coating gun 5 is turned on, and the time delay until the set flow rate Q ₁ is reached as in the past can be completely eliminated. Can be done.

Next, when the coating gun 5 is turned on, the CPU
100 activates relay 109 (step);
Set the set flow rate _Q1 (step, the set flow rate
It outputs the speed control signal V ₁ of the servo motor 6 that gives Q ₁ (step), and at the same time outputs the coating gun 5.
Turn on (step) and operate the constant displacement pump 3 at a constant speed corresponding to the set flow rate _Q1 . During this constant speed operation, the constant volume pump 3 is feedback-controlled by the feedback signal from the speed detector 7 to operate at a constant speed, and continues to supply the sealer 1 at a constant flow rate _Q1 to the coating gun 5. Therefore, the viscous fluid is discharged from the coating gun 5 at a constant flow rate over the entire period immediately after the start of discharge.

Effects of the Invention Since the method of the present invention has the above-described structure and operation, a constant flow rate can always be obtained even if the viscosity of the viscous fluid changes depending on the temperature, and the flow rate is stable even after the dispensing gun starts discharging. Since the flow rate can be kept at a constant flow rate, the accuracy in flow rate control can be significantly improved.

Further, since a constant flow rate can be obtained after the coating gun starts discharging, it is effective in ensuring stable sealing quality when used in an automatic sealing fluid supply device or the like. Furthermore, by changing the temperature-supply pressure characteristic data, the present invention can be easily changed and applied to any viscous fluid with different temperature-viscosity characteristics, resulting in extremely high versatility.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of a device constructed by applying the method of the present invention, FIG. 2 is a specific circuit configuration diagram of the control unit in FIG. 1, and FIG. The flowchart, FIG. 4, is an example of temperature-supply pressure characteristic data. 1: Sealer (viscous fluid), 3: Fixed displacement pump,
4: Hose, 5: Application gun, 6: Servo motor,
7: Speed detector, 10: Control unit, 11: Temperature sensor, 12: Pressure sensor, 15: Air source, 1
7: Solenoid valve.

Claims (1)

[Claims] 1 In a method of pumping and supplying viscous fluid to an on-off type coating gun using a constant volume pump, when the viscous fluid is not being discharged from the coating gun and is in the off state, the inside of the hose connecting the constant volume pump and the coating gun is Detect the temperature and pressure of the viscous fluid, calculate the supply pressure to obtain the desired set flow rate at the detected temperature from preset temperature-supply pressure characteristic data, and combine the calculated supply pressure and the detected pressure. The discharge pressure of the constant displacement pump is controlled so that the detected pressure matches the supply pressure, and when the viscous fluid is being discharged from the dispensing gun, the discharge pressure is controlled at a constant speed that provides the desired set flow rate. A method for controlling the flow rate of a viscous fluid, comprising operating the constant displacement pump at a constant speed.